机械设计外文翻译(中英文)
机械设计中英文外文翻译文献
(文档含英文原文和中文翻译)中英文资料外文翻译Fundamentals Of Machinery DesignThis introductory chapter is a general survey of machinery design．First it presents the definition and major role of machinery design，the relationship between machineryand its components．Then it gives an overview of machinery design as a fundamental course and outlines a general procedure of machinery design followed by all the engineers．Finally, it lists the contents of the course and the primary goals to be achieved．1．1 The role of machinery designMachinery design is to formulate all engineering plan．Engineering in essence is to utilize the existing resources and natural law to benefit humanity．As a major segment of engineerin，machinery design involves a range of disciplines in materials，mechanics，heat，flow，control，electronics and production．Although many hightechnologies are computerized and automated，and are rapidly merged into Our daily life，machines are indispensable for various special work that is difficult or impracticable to be carried out by human．Moreover，machinery can significantly improve efficiency and quality of production，which is crucial in current competitive global market．In the modern industrialized world，the wealth and living standards of a nation are closely linked with their capabilities to design and manufacture engineering products．It can be claimed that the advancement of machinery design and manufacturing can remarkable promote the overall level of a country’s industrialization．Those nations，who do not perform well in design and manufacture fields，are not competitive in world markets．It is evident that several countries that used to be leaders in the design and manufacturing sectors until the l 960s and the1 970s had，by the l990s，slipped back and lost their leadership．On the contrary, our Country is rapidly picking up her position in manufacturing industry since the l 9 80s and is playing a more and more vital role in the global market．To accelerate such an industrializing process of our country, highly skilled design engineers having extensiveknowledge and expertise are needed．That is why the course of machinery design is of great significance for students of engineering．The course of machinery design is considerable different from those background subjects in science and mathematics．For many students，it is perhaps one of their basic professional engineering courses concerned with obtaining solutions to practical problem s．Definitely these solutions must clearly represent an understanding of the underlying science，usually such an understanding may not be sufficient，empirical knowledge or engineering judgement has to be also involved．Furthermore，due to be professional nature of this subject，most design problems may not have one right solution．Nevertheless it is achievable to determine a better design from all feasible solutions．1．2 Machinery and componentsA state-of-the-art machine may encompass all or part of mechanical，electrical，control，sensor，monitoring and lubricating sub—systems．Intermsof the functions of those parts，the machine can also be viewed to be comprised of power，transmission，execution and control／manipulation parts．Regardless of the complexity, however，the major functional part may be still the mechanical system．Forconvenience of analysis，the mechanical system can be decomposed int0．mechanisms that are designed to execute some specific tasks．And the mechanism can be further decomposed into mechanical components．In this sense，the mechanical components are the fundamental elements of machinery．On the whole，mechanical components can be classified as universal and special components．Bolts，gear and chains are the typical examples of the universal components which can be used extensively in different machines across various industrial sectors．Turbine blades，crankshaft and aircraft propeller are the examples ofthe special components，which Can be used extensively in different machines across various industrial sectors．turbine blades，crankshaft and aircraft propeller arethe examples of the special components，which are designed for some specific purposes．In addition to this，if a number of components are manufactured，assembled and even equipped as an individual system，e．g．leaf spring setin a vehicle，it is also termed as a mechanical part．A good machine definitely requires quality individual components．Thus，the design of components is very important．When designing a machine，on the otherhand，engineers invariably find that requirements and constraints of its components areinterrelated．As a local portion，the component is expected to play a certain role on the machine and therefore must be appropriately restrained by the whole system．The design of a gear drive in a speed—reducer，for instance，depends upon not only the strength and stiffness，but also the space available for the gears in the shaft and relation with other transmission drive．This means that the design of the mechanical components inevitably requires a whole view in the whole system．Due to relationship between a machine and its components，the process of machinery design usually covers interconnected designs of machine，parts，and components．Any modification and adjustment in one component may considerably affect the designs of other components or parts．To present the best possible design solution，the iteration of evaluation，analysis and optimization across all the process seem indispensable．1．3 Overview of machinery designThis course is primarily concerned with the design of specific components of machines or mechanical systems．Competence in this area is basic to the consideration and synthesis of complete machines and systems in subsequent courses and professional practice．It Can be seen that even the design of a single bolt or spring needs the designer’s thorough understanding of the principles and methods ofmachinery design together with empirical information，good judgment and even a degre3e of ingenuity in order to produce the best product for the society today．It is natural that designing engineers give first consideration to the functional and economic aspects of new products or devices．Machinery design needs to ensure safetyand reliability in a prescribed lifetime．To address such a problem conventionally，the technical consideration of the mechanical component design is largely centered around two main areas of concerns：(1) strength-stiffness-stability criteria involving the bulk of a solid member and (2) surface phenomena including friction，lubrication，weal7，and environmental deterioration．However，in comparison with such relatively straightforward computations as stress and deflection，the design determination of safety and reliability is likely to be an elusive and indefinite matter，complicated by psychological and sociological factors．It must be kept in mind that safety and reliability are inherently relative to each other，and the value judgmentsmust be made with regard to trade—offs between safety，reliability，cost，weight，and soforth．On the other hand，a practical design needs to reflect clearly manufacturability and economy to make sure of the lowest cost as well as the least consumption of energy and materials．Otherwise，the products or devices designed will be of no further engineering or commercial interests．Nowadays，the simultaneous considerations of manufacturing and assembly factors phases including design，manufacturing，inspection，asassembly and other is considered in such a parallel fashion that the quality and cost arebest satisfied concurrently．In addition to these traditionally technological and economic considerations fundamental to the design and development of mechanical components and systems，the modern engineers have become increasingly concerned with the broader considerations of sustainability，ecology，aesthetics，ergonomics，maintainability，andoverall quality of life．It is clear that a greater than ever engineering effort is being recently devoted to broader considerations relating to the influences of engineered products on people as well as on the environment．The following is a list of general factors for engineers to consider in the design process，which from a different viewpoint shows us a panoramic picture with regard to the design-related activities and tasks．(1) Cost of manufacturing．Will the selling price be competitive? Are there cheaper ways of manufacturing the machine? Could other materials be used? Are any special tools，dies, jigs，or fixtures needed? Can it easily be inspected? Can the workshop produce it? Is heat treatment necessary? Can parts be easily welded?第4页Cost of operation．Are power requirements too large? What type of fuelwill be used? Will operation cost be less expensive?(3) Cost of maintenance．Are all parts easily accessible? Are access panels needed? Can common tools be used? Can replacement parts be available?(4) Safety features．Is a suitable factor of safety used? Does the safety factor meet existing codes? Are fuses，guards，and／or safety valves used? Are shear pins needed? Is there any radiation hazard? Any overlooked ”stress raiser”? Are there any dangerous fumes?(5) Packaging and transportation．Can the machine be readily packaged for shipping without breakage? Is its size suitable to parcel post regulations, freight car dimensions，or trailer truck size? Are shipping bolts necessary? Is its center of gravity in a desirable location?(6) Lubrication．Does the system need periodic checking? Is it automatic? Isit a sealed system?(7) Materials．Are chemical，physical，and mechanical properties suitable to its use? Is corrosion a factor? Will the materials withstand impact? Is thermal or electrical conductivity important? Will high or low temperatures present any problem? Will design stress keep parts reasonable in size?(8) Strength．Have dimensions of components been carefully calculated? Have all the load cases be taken into account? Have the stress concentrations been carefully considered? Has the fatigue effect be computed?(9) Kinematics．Does it provide necessary motion for moving parts? Are rotational speeds reasonable? Could linkages replace cams? What will be the best choice，the belts，chains or gears? Is intermittent motion needed?(10) Styling．Does the color have eye appeal? Is the sharp desirable? Is the machine well proportioned? Are the calibrations on dials easily read? Are the controls easy to operate?(11) Drawings．Are standardized parts used? Are the tolerances realistic? Is the surface finish over-specified? Must the design conform to any standards?(12) Ergonomics．Has the operator of the equipment been considered? Are the controls conveniently located to avoid operator fatigue? Are knobs，grab bars，hand wheels，levers，and dial calibrations of proper size to fit the average operator?1．4 A general procedure of machinery designWhatever design tasks the designers are expected to complete，theyalways，consciously or unconsciously，follow the similar process which goes as follows：(1)Studies of feasibilityAfter understanding the product functions，operational conditions，manufacturing constraints and key technologies，go on to uncover existing solutions to some similar problems so as to clarify the design tasks，understand the needs，present the major functional parameters and evaluate design tasks，proposal of design aims，and feasibility analysis．(2) Conceptual design of configurationAccording to the design of tasks and functional parameter，designs need to extensively search for various feasible configurations and alternatives．Forconvenience，usually，the system can be analyzed comprehensively by decomposing itinto power sources，transmission and work mechanisms．A great effort needs to be devoted to the analysis and synthesis of these different parts．For example，the power source may be selected from motor，engine and turbine．Each power source may have a range of power and kinematical parameters ．Similarly, power trains may have numerous optionsavailable，e．g．belts，chains，gears，worm gears and many other drives．Obviously selecting an appropriate configuration would guarantee the Success of the whole design and the quality of the products．To make a best possible decision，an iterative process is normally required to select，analyze，compare and evaluate different configurations．At this stage，the goals involve sketching of configuration，determination of kinematical mechanisms，and evaluation of functional parameter(power and kinematics)．(3)Detailed technical designBased on the design of configuration and parameters，a number ofassembly and component drawings will be completed to reflect the detaileddesign including kinematics，power，strength，stiffness，dynamics，stability，fatigue and SO on．Consideration should also be given to manufacturingfactors by presenting structural details，materials，and both geometricand dimensional tolerances．This part of work will also be carried out ina repeated process in drawings，calculation，evaluation and modificationuntil a best possible design is achieved．The goal at this stage is tocomplete assembly and component drawings，structural details，design calculations and detailed technical documentations．(4)Modification of designAfter the design is completed，a prototype is usually made for a more realistic physical assessment of the design quality．This will help correct any drawback or fault that may be overlooked or neglected during the design process．At this stage，the goal is to correct the design imperfection，test the potential manufacturing or assembly flaws and refine /improve design．1．5 Contents and tasks of the courseThe course Machinery Design will cover the following contents：(1)Preliminaries．the fundamental principles of machinery andComponents design，design theory，selection of materials，structure，friction，wear and lubrication．(2)Connection．sand．joints．thread．fasteners，keys，rivets，welds，bonds ．and adhesive and interference joints．(3)Transmission．screws，chains，belts，gears，worms，bevel．gearsAnd helical gears．(4)Shaft．system．rolling—contact．bearings，slidingbearings，clutches，couplings，shafts，axles and spindles．(5)Other part s．springs，housings and frame s．The course centers on engineering design of mechanical components andis in a category of fundamental methodology and procedure．It is notfeasible or realistic for the students to become involved in the detaileddesign considerations associated with all machine components．Instead，the textbook has its main focus on some typical components and parts．However，the methodologies and procedures to be developed in this course can beextended to more design cases．For this reason，an emphasis will be laidon the methods and procedure s over the course so that the student s willgain a certain competence in applying these skills and knowledge todesigning more mechanical components．As a professional fundamental course，it will help students to acquirea sol id knowledge of mechanical design and engineering awareness．More specifically，the course will help to develop the students’ competence inthe following facets：Competence of creative design and solving practical problem；Competence of team work as well as professional presentation and communications：Competence of apprehending the design principles andregulations，synthesizing the knowledge to develop new designs：Competence of engineering research as well as using designcode s，handbooks，standards and references：Competence of doing experiments to solve problem in the design oftypical components：Competence of understanding newly introduced technological as well aseconomic codes to update the knowledge of machinery design．It is worth noticing that the course will also integrate a number ofpreceding relevant subjects at the university—level ，including mathematics ，physics，electronics，chemistry，solid mechanics，fluid mechanics，heat transfer，thermodynamics，computin9，and so forth．It will combine the knowledge about science and professional skills to solve some practical engineering problems，which will significantly advance students’ competence and enlarge their vision to the professional engineers．It should be pointed out that skills and experience could beacquired only by a great deal of practice——hour after monotonous hour ofit．It is acknowledged universally that nothing worthwhile in life canbe achieved without hard work，often tedious，dull and monotonous，and engineering is no exception．机械设计的基本原则这个导言章节是对机械设计的一个纵览。
机械设计专业外文文献翻译
机械设计专业外文文献翻译general。
however。
materials that are easy to machine have high machinability。
while those that are difficult to machine have low XXX。
microstructure。
and mechanical properties。
as well as the XXX。
material。
and wear resistance.XXX factors。
cutting speed。
feed rate。
and depth of cut also play XXX the amount of heat generated in the cutting zone and decreasing the time that the cutting tool is in contact with the XXX。
at high cutting speeds。
tool wear and cutting forces can increase。
which can ce tool life and surface finish quality.Feed rate and depth of cut also XXX the amount of material that is removed and the forces that are generated during cutting。
Higher feed rates and deeper cuts can improve material removal rates。
but they can also increase cutting forces and heat n。
which can ce tool life and surface finish quality.Overall。
机械设计及其自动化外文翻译数控机床
英文】High-speed machining the development ofHigh-speed machining is oriented to the 21st century a new high-tech, high-efficiency, High-precision and high surface quality as a basic feature, in theautomobile industry, aerospace, Die Manufacturing and instrumentation industries gained increasingly widespread application, and has made significant technical and economic benefits. contemporary advanced manufacturing technology an important component part 。
High-speed machining is to achieve high efficiency of the core technology manufacturers, intensive processes and equipment packaged so that it has a high production efficiency. It can be said that the high-speed machining is an increase in the quantity of equipment significantly improve processing efficiency essential to the technology. High-speed machining is the major advantages : improve production efficiency, improve accuracy and reduce the processing of cutting resistance。
机械设计类英文文献及翻译
The Sunflower Seed Huller and Oil PressBy Jeff Cox-- from Organic Gardening, April 1979, Rodale PressIN 2,500 SQUARE FEET, a family of four can grow each year enough sunflower seed to produce three gallons of homemade vegetable oil suitable for salads or cooking and 20 pounds of nutritious, dehulled seed -- with enough broken seeds left over to feed a winter's worth of birds.The problem, heretofore, with sunflower seeds was the difficulty of dehulling them at home, and the lack of a device for expressing oil from the seeds. About six months ago, we decided to change all that. The job was to find out who makes a sunflower seed dehuller or to devise one if none were manufactured. And to either locate a home-scale oilseed press or devise one. No mean task.Our researches took us from North Dakota -- hub of commercial sunflower activity in the nation -- to a search of the files in the U.S. Patent Office, with stops in between. We turned up a lot of big machinery, discovered how difficult it is to buy really pure, unrefined vegetable oils, but found no small-scale equipment to dehull sunflowers or press out their oil. The key to success, however, was on our desk the whole time. In spring 1977, August Kormier had submitted a free-lance article describing how he used a Corona grain mill to dehull his sunflower seeds, and his vacuum cleaner exhaust hose to blow the hulls off the kernels. A second separation floated off the remaining hulls, leaving a clean product. We'd tried it, but because some kernels were cracked and the process involved drying, we hadn't been satisfied. Now we felt the best approach was to begin again with what we learned from Mr. Kormier and refine it.Staff Editor Diana Branch and Home Workplace Editor Jim Eldon worked with a number of hand- and electric-powered grain mills. While the Corona did a passable job, they got the best results with the C.S. Bell #60 hand mill and the Marathon Uni Mill, which is motor-driven. "I couldn't believe my eyes the first time I tried the Marathon," Diana says. "I opened the stones to 1/8th inch, and out came a bin full of whole kernels and hulls split right at the seams. What a thrill that was!"She found that by starting at the widest setting,and gradually narrowing the opening, almost every seed was dehulled. The stones crack the hulls open, then rub them to encourage the seed away from the fibrous lining. The Bell hand mill worked almost as well. "As long as the stones open at least as wide as the widest unhulled seed, any mill will work," she says.Because the seed slips through the mill on its flat side, grading is an important step to take before dehulling. We made three sizing boxes. Thefirst is 1/4-inch hardware cloth [wire screen]. The second is two layers of1/4-inch cloth, moved slightly apart to narrow the opening in one direction, and the third is two layers of screen adjusted to make a still-smaller opening. Since the smallest unhulled seeds are about the size of the largest hulled kernels, the grading step prevents these undersized seeds from passing through unhulled. Processed together at a closer setting, the smallest seeds hulled out.Jim Eldon's workshop is littered with strange-looking pieces of apparatus. They represent initial attempts to build a workable winnowing box, using Kormier's vacuum exhaust idea for a source of air. Jim, Fred Matlack and Diana finally made a box with a Plexiglas front, through which they could observe what was happening.They cut a hole in the back of the box with a sliding cover to regulate the air pressure, and fiddled with various arrangements of baffles. The result was a stream of hulls exiting through one hole while the kernels fell to the bottom of the box. Now they were ready to try a five-pound sample of unhulled sunflower seeds to see how much they could recover.The five pounds were graded and dehulled, then winnowed. We got about one hull for every ten kernels in the final, winnowed product. These are easily picked out. They usually contain kernels still held behind the fibrous strings of the hull. Their weight prevents them from blowing out with the empty hulls. We found that bug-eaten seeds do blow away with the chaff, which was a bonus for cleanliness of the final product. Toss the hulls to the birds, who will find broken seeds among them.Starting with 80 ounces of unhulled seed, we ended up with 41-1/4 ounces of edible whole seeds, 1.8 ounces of damaged seeds suitable for animal feed, and 36.6 ounces of hulls. It took us about an hour. Notbad.Sunflower seeds store perfectly in the hulls, but they deteriorate more rapidly when shelled out. The grain mill dehuller and winnowing box give the gardener a way to have the freshest possible seeds for eating at all times of the year. With the construction of one more piece of equipment -- the oil press -- he can have absolutely fresh, unrefined, polyunsaturated sunflower oil for salads, mayonnaise and cooking.Most light, refined vegetable oils have been extracted using hexane, a form of naphtha. The oil is then heated to boil off the hexane. Lye is dumped into it. It's washed with steam, then heated to remove odors and taste before being laced with preservatives and stabilizers. It may feel oily in the mouth, but you might as well taste air. No so with fresh-made sunflower oil -- it's deliciously yet subtly nutty in flavor, adding unsurpassed flavor to salads.There's good reason to believe that sunflower oil may become the #1 vegetable oil in the U.S. in a few years. It's already #1 in health-conscious Europe. Corn oil has already caught on here for health reasons, and sunflower oil is so much better. Sunflower oil's 70 percent polyunsaturate is just under safflower, with corn oil bringing up the rear with 55 percent. And sunflowers yield 40 percent oil, soybeans only 20 percent.Our oil press isrelatively simple, but it must be welded together. Check the construction directions for details. The press consists of a welded tubular frame which accepts a three-ton hydraulic jack. You may already have one. If not, it can be purchased at most auto and hardware stores for about $16. A metal canister with holes drilled in its sides and one end welded shut holds the mashed sunflower seeds. A piston is inserted in the canister and then inverted and slipped over a pedestal on the frame. The jack is set in place, and the pressure gradually increased over half an hour. The oil drips from the sides of the canister into a tray -- the bottom of a plastic jug slipped over the pedestal works fine -- which empties the oil into a cup. You can filter the oil with a coffee filter to remove pieces of seed and other fine particles that would burn if the oil were used for cooking. If it's for salads or mayonnaise, there's no need to filter it.We first tried using "confectionary" sunflower seeds for oil. These are the regular eating kernels we're used to seeing. They give less than half as much oil as the oilseed types of sunflower. Although you can use confectionary types such as MAMMOTH RUS- SIAN for oil, don't expect to get more than an ounce and a half from a pound of seed. Oilseed produces three or more ounces of oil from a pound of seed and is well worth planting along with confectionary-type seeds. Oilseed has another big advantage -- to prepare it, you can put the whole, unhulled seed into a blender and whiz it until it forms a fine meal, while confectionary seeds must be dehulled first. The entire sequence of grading, dehulling and winnowing is avoided with oilseed.Oil types produce about a tenth of a pound of seed per head in commercial production. Gardeners, with their better soil and care, invariably do better than that. Our conservative estimate is that 1,280 plants will be enough for three gallons of oil. Spaced one foot apart in rows two feet apart, 1,280 oilseed plants will take a space 40-by-56 feet, or 80-by-28 if you want a more rectangular patch to face south.We worked in pound batches, since the canister just holds one pound of mash. After blending, we heated it to 170 degrees F. (77 deg C) by placing it in a 300-degree F. (149 deg C) oven and stirring it every five minutes for 20 minutes. Heating gets the oil flowing and doubles the yield of oil. In case you're wondering,"cold-pressed" oils sold commercially are also heated, and some are subjected to the entire chemical process. The term has no firm meaning within the industry, according to the literature we've surveyed.Heating does not change the structure of fats. It will not turn polyunsaturated fats into saturated fats. In fact, Dr. Donald R. Germann in his book, "TheAnti-Cancer Diet", says that "... an unsaturated fat must be heated to high temperatures -- above 425 degrees F. or 200 degrees C. -- at least 8 or 10 times before any shift toward saturation occurs..." Dean C. Fletcher, Ph.D., of the American Medical Association Department of Foods and Nutrition in Chicago, says, "It's true that either high temperature or repeated heatingdoes change the nature of some of the unsaturated oil molecules. (But) the flavor of the oil changes as these chemical changes occur, spoiling its taste. This effect is probably more profound than any of the physiological changes the altered oil might produce within the body."From 500 gm. of heated mash, we pressed 89 gm. of oil, 89 percent of the entire amount available and twice as much as we could press from unheated oil! The decision is up to you whether or not to heat the mash, but that extra 50 percent seems like an awful lot, especially when the whole technique is so labor intensive. The oil should be stored in the refrigerator, and it's probably best to use it within a month, since it has no preservatives. Mayonnaise made with such fresh oils should be kept refrigerated and used within two weeks. The leftover cake, still containing 50 percent of its oil, is a nutritious addition to your dishes, and makes excellent feed for animals or winter birds. Store the pressed cake in the freezer.We're talking then about a sunflower patch with two kinds of plants -- confectionary such as MAMMOTH RUSSIAN and oilseed such as PEREDOVIK. The oilseed plants should be grown 12 inches apart in rows two feet apart. Four average confectionary heads yield about a pound of unhulled seed. You'll need about 35 pounds of unhulled seed, or 140plants-worth, to yield 20 pounds of hulled kernels, about what a family of four will use in a year. That many plants can be grown in an area 26-by-10 feet. That's 260 square feet. Put that together with the 2,240 square feet for the oilseed sunflowers, and you need a patch about 2,500 square feet -- 25 100-foot rows -- to keep yourself supplied year-round with super nutrition and unsurpassable taste.Winnowing Machine For Sunflower SeedsThe winnowing machine operates on the age-old principle of blowing the chaff away from the heavy grain with a controlled current of air.The unit uses a household or shop-type vacuum cleaner for its air supply. A vacuum cleaner was used as a power source because it can supply a large volume of air over an extended period of time, and most homes and farms have a vacuum cleaner.A cloth bag has been attached to the chaff chute to catch the chaff as it is separated from the seed. The bag allows the hulls to be collected and greatly reduces the amount of waste material normally blown into the air by conventional systems.The unit has been constructed in such a way that the cloth bag and cleaner box can be placed inside the seed box, making a compact package for storage.Tools Required1. Table Saw2. Drill Press3. Band Saw4. Saber SawProcedure (cleaner box)1 . Cut out the two sides of the cleaner box from 1/4-inch plywood.2. Cut out the six interior pieces of the cleaner box from 3/4 x 3-1/2-inch select pine.3. Assemble the cleaner box elements with glue and nails.4. Cut four 1/4-inch square strips of pine four inches long.5. Glue the strips around the end of the chaff chute.6. Sand all surfaces and edges.7. Finish with clear lacquer finish.Procedure (seed box)1. Cut two pieces of pine /34" x 5 /12 x 15 inches for the sides.2. Cut two pieces of pine 3/4 x 5-1/2 x inches for the top and bottom.3. Plow a /14 x 1/4 groove for the front and back panels in all four pieces.4. Rip the top board to 5 inches so that the front panel can slide into the grooves in the side boards.5. Rabbet both ends of each 15-inch side piece to accept the top and bottom boards.6. Drill a hole in the left side board 2-1/2 inches from the top. The size of the hole is determined by the vacuum cleaner hose fitting.7. Cut a 3-1/4 x 4 inch hole in the top 1/2 inch from the right end. This hole will accept the cleaner box.8. Cut two pieces of pine for the baffle.9. Drill two 1-inch holes in the bottom of the baffle box.10. Cut a piece of 1/4 x 8-1/2 x 14 inch plywood for the back panel.11. Cut a 3-inch hole, centered 1-7/8 inches from the top and left sides of the plywood back.12. Assemble the sides, baffles, top, bottom, and back panel with glue and nails.13. Cut an 8-7/16 x 15-3/4-inch piece of Plexiglas for the front.14. Cut a one-inch radius on the top corners of the front.and sand the edges.15. Drill a one-inch thumb hole centered 7/8 inch from the top edge.16. Cut a 3-1/2-inch disk of 1/4-inch plywood for the vent cover.17. Drill a 3/16-inch hole 3/8 inch from the edge of the disk.18. Mount the disk over the vent with a #10 x 1-inch screw.19. Sand all surfaces and edges of the, box.20. Finish with clear lacquer finish.MaterialsCleaner Box2 -- 7-3/4 x 7-1/2 x 3/4" plywood (sides)6 -- 3/4 x 3-1/2 x 24" for all members (baffles)4 -- 1/4 x 1/4 x 4" pine (chute cleats)22 -- 1" x 18 ga. headed nailsWhite vinyl glueClear lacquer finishSeed Box2 -- 3/4' x 5-1/2 x 15" select pine (sides)2 -- 3/4 x 5-1/2 x 8-1/2" select pine (top and bottom)1 -- 3/4 x 3-1/2 x 4-1/2" select pine (baffle)1 -- 3/4 x 4-1/2 x 4-1/2" select pine (baffle)1 -- 1/4 x 8-1/2 x 14" plywood (back)1 -- 1/4 x 3-1/2" dia. plywood (control valve)1 -- 1/4' x 8-7/16 x 15-1/4" Plexiglas (front)1 - #10 x 1" flat head screw18 - 4d finish nailsWhite vinyl glueClear lacquer finish1 -- 17 x 31" cloth laundry bagSunflower Seed Oil PressThe press was designed so that homesteaders can produce sunflower oil from their own seeds. The oil can be pressed as is or heated to 170 degrees F., which doubles oil yield.Both methods require the seed to be ground to fine powder. If you are pressing the oil seed variety, a meat grinder or electric blender will do an excellent job of grinding the seed. The confectionary type of seed will require the seed to be hulled and winnowed before it is ground. A food mill with the stones set at the coarse setting can be used to accomplish this step. The ground kernels are placed in the cylinder with the piston closing the bottom portion of the cylinder.The cylinder is mounted in the press frame and a three-ton hydraulic jack is used to supply the pressure.Because of the great pressures created by the hydraulic jack, it is important that the frame be properly constructed and firmly mounted to the work surface before the pressing operation begins. The following instructions can be given to a welder.Tools Required1. Power Hacksaw2. Metal Band Saw3. Metal Lathe4. Drill Press5. Belt or Disk Grinder6. Arc Welder7. Hand ClampsProcedure (Frame)1. Cut two pieces of 1-3/4" O.D. x 1-3/8" I.D. x 24-1/2 inch long tubing for the uprights.2. Cut one piece of 1-3/4" O.D. x 1-3/8" I.D. x 6-1/2 inch long tubing for the center tube.3. Cut one 3/4" x 2-3/4 x 5-1/2 inch steel bar for the top cross member.4. Cut two pieces of 1-3/4 x 1-3/4 x 8 inch angle iron for the base members.5. Drill two 9/32-inch holes in each base member 1/2 inch from the outer edges.6. Weld the base members, tubes and cross member together as per the drawing.7. Grind all edges to remove any burrs.8. Paint the frame.9. If a mounting board is desired, cut a piece of pine 1-1/4 x 6-1/2 x 12 inches long.10. Center the frame on the board and mark the location of the four mounting holes.11. Drill four 7/8-inch holes 1/4-inch deep to accept the T-nuts.12. Drill four 5/16-inch holes through the mounting board using the same centers created by the 7/8-inch holes.13. Round the edges of the base and sand all surfaces.14. Install four 1/4-20 T-nuts.15. Finish the base with clear lacquer finish.16. Assemble the base to the frame using four 1/4-20 x 1-1/4-inch round head bolts.Procedure (Cylinder)1. Cut a piece of 3-1/2" O.D. x 3-1/4" I.D. tubing 5-3/8 inches long.2. Face both ends on the lathe.3. Cut out a 3-1/2-inch round disk from 1/4-inch plate steel.4. Weld the disk to one end of the tube.5. Drill a series of 3/32-inch holes around the side of the tube on 1/2-inch centers.6. Remove all burrs on the inside and outside of the tube.Procedure (Piston)1. Cut out a 3-3/8-inch disk of 1/4-inch plate steel.2. Cut a 1-3/8" O.D. x 1-1/8" I.D. piece of tubing 1-1/8 inches long.3. Face both ends of the tube.4. Weld the tube in the center of the 3-3/8-inch disk. All welds should be made on the inside of the tube.5. Mount the piston in the lathe and turn the disk to fit the inside diameter of the cylinder. This will be about 3-15/64 inches in diameter.6. Remove any sharp edges.Procedure (Collector Ring)1. Cut the bottom out of a one-gallon plastic bottle. The cut line should be approximately 1-1/2 inches from the bottom of the bottle.2. Make a 1/8 x 1 inch slot at one edge of the bottom outside ring. This will allow the oil to pour into a receiving cup.3. Cut a 1-3/4-inch hole in the center of the bottom, so that the unit will fit over the center tube in the frame.MaterialsFrame2 -- 1-3/4 O.D. x 1-3/8 I.D. x 24-1/2" long H.R.S. (frame tubes)1 -- 1-3/4 O.D. x 1-3/8 I.D. x 6-1/2 inch long H.R.S. (center tube)1 -- 3/4 x 2-3/4 x 5-1/2" flat bar H.R.S. (top cross member)2 -- 1-3/4 x 1-3/4 x 8" angle iron H.R.S. (base members)1 -- 1-1/4 x 6-1/2 x 12" #2 white pine (wood base)4 -- 1/4-20 x 1-1/4 R.H. mounting bolts4 -- 1/4-20 T-nutsBlack enamel for frame (finishing material)Clear lacquer finish for wood base3 -- 1/8" dia. welding rodsCylinder1 -- 1/4 x 3-1/2" dia. C.R.S. disk (top)1 -- 3-1/2 O.D. x 3-1/4 I.D. C.R.S. tube (cylinder)1 -- 1/8 dia. welding rodPiston1 -- 1/4 x 3-3/8 D.A. C.R.S. disk (piston top)1 -- 1-1/4 O.D. x 1 I.D. x 1" long H.R.S. (piston tube)1 -- 1/8 dia. welding rodCollector Ring1 -- Bottom from a one-gallon plastic bottle (oil collector ring)葵花籽脱壳机和油压机由Jeff考克斯-从有机园艺，1979年4月，罗代尔新闻2,500平方尺，一个四口之家每年可以长到足以产生三种葵花籽国产蔬菜沙拉或烹调油和20磅的营养丰富，适合脱皮加仑种子 - 与遗留养活一个冬天的产值，破碎的种子鸟类。
机械设计外文翻译--- 轴承的摩擦与润滑
毕业设计（论文）外文翻译毕业设计（论文）题目：外文题目：Friction , Lubrication of Bearing 译文题目：轴承的摩擦与润滑系别：机械工程系专业：机械工程制造及其自动化班级：学号：姓名：指导教师：2012年03 月03 日外文文献原文：Friction , Lubrication of BearingIn many of the problem thus far , the student has been asked to disregard or neglect friction . Actually , friction is present to some degree whenever two parts are in contact and move on each other. The term friction refers to the resistance of two or more parts to movement.Friction is harmful or valuable depending upon where it occurs. friction is necessary for fastening devices such as screws and rivets which depend upon friction to hold the fastener and the parts together. Belt drivers, brakes, and tires are additional applications where friction is necessary.The friction of moving parts in a machine is harmful because it reduces the mechanical advantage of the device. The heat produced by friction is lost energy because no work takes place. Also , greater power is required to overcome the increased friction. Heat is destructive in that it causes expansion. Expansion may cause a bearing or sliding surface to fit tighter. If a great enough pressure builds up because made from low temperature materials may melt.There are three types of friction which must be overcome in moving parts: (1)starting, (2)sliding,and(3)rolling. Starting friction is the friction between two solids that tend to resist movement. When two parts are at a state of rest, the surface irregularities of both parts tend to interlock and form a wedging action. To produce motion in these parts, the wedge-shaped peaks and valleys of the stationary surfaces must be made to slide out and over each other. The rougher the two surfaces, the greater is starting friction resulting from their movement .Since there is usually no fixed pattern between the peaks and valleys of two mating parts, the irregularities do not interlock once the parts are in motion but slide over each other. The friction of the two surfaces is known as sliding friction. As shown in figure ,starting friction is always greater than sliding friction .Rolling friction occurs when roller devces are subjected to tremendous stress which cause the parts to change shape or deform. Under these conditions, the material in front of a roller tends to pile up and forces the object to roll slightly uphill. This changing of shape , known as deformation, causes a movement of molecules. As a result ,heat is produced from the added energy required to keep the parts turning and overcome friction.The friction caused by the wedging action of surface irregularities can be overcome partly by the precision machining of the surfaces. However, even these smooth surfaces may require the use of a substance between them to reduce the friction still more. This substance is usually a lubricant which provides a fine, thin oil film. The film keeps the surfaces apart and prevents the cohesive forces of the surfaces from coming in close contact and producing heat .Another way to reduce friction is to use different materials for the bearing surfaces and rotating parts.This explains why bronze bearings, soft alloys, and copper and tin iolite bearings are used with both soft and hardened steel shaft. The iolite bearing is porous. Thus, when the bearing is dipped in oil, capillary action carries the oil through the spaces of the bearing. This type of bearing carries its own lubricant to the points where the pressures are the greatest.Moving parts are lubricated to reduce friction, wear, and heat. The most commonly used lubricants are oils, greases, and graphite compounds. Each lubricant serves a different purpose. The conditions under which two moving surfaces are to work determine the type of lubricant to be used and the system selected for distributing the lubricant.On slow moving parts with a minimum of pressure, an oil groove is usually sufficient to distribute the required quantity of lubricant to the surfaces moving on each other .A second common method of lubrication is the splash system in which parts moving in a reservoir of lubricant pick up sufficient oil which is then distributed to all moving parts during each cycle. This system is used in the crankcase of lawn-mower engines to lubricate the crankshaft, connecting rod ,and parts of the piston.A lubrication system commonly used in industrial plants is the pressure system. In this system, a pump on a machine carries the lubricant to all of the bearing surfaces at a constant rate and quantity.There are numerous other systems of lubrication and a considerable number of lubricants available for any given set of operating conditions. Modern industry pays greater attention to the use of the proper lubricants than at previous time because of the increased speeds, pressures, and operating demands placed on equipment and devices.Although one of the main purposes of lubrication is reduce friction, any substance-liquid , solid , or gaseous-capable of controlling friction and wear between sliding surfaces can be classed as a lubricant.V arieties of lubricationUnlubricated sliding. Metals that have been carefully treated to remove all foreign materials seize and weld to one another when slid together. In the absence of such a high degree of cleanliness, adsorbed gases, water vapor ,oxides, and contaminants reduce frictio9n and the tendency to seize but usually result in severe wear; this is called “unlubricated ”or dry sliding.Fluid-film lubrication. Interposing a fluid film that completely separates the sliding surfaces results in fluid-film lubrication. The fluid may be introduced intentionally as the oil in the main bearing of an automobile, or unintentionally, as in the case of water between a smooth tuber tire and a wet pavement. Although the fluid is usually a liquid such as oil, water, and a wide range of other materials, it may also be a gas. The gas most commonly employed is air.Boundary lubrication. A condition that lies between unlubricated sliding and fluid-film lubrication isreferred to as boundary lubrication, also defined as that condition of lubrication in which the friction between surfaces is determined by the properties of the surfaces and properties of the lubricant other than viscosity. Boundary lubrication encompasses a significant portion of lubrication phenomena and commonly occurs during the starting and stopping off machines.Solid lubrication. Solid such as graphite and molybdenum disulfide are widely used when normal lubricants do not possess sufficient resistance to load or temperature extremes. But lubricants need not take only such familiar forms as fats, powders, and gases; even some metals commonly serve as sliding surfaces in some sophisticated machines.Function of lubricantsAlthough a lubricant primarily controls friction and ordinarily does perform numerous other functions, which vary with the application and usually are interrelated .Friction control. The amount and character of the lubricant made available to sliding surfaces have a profound effect upon the friction that is encountered. For example, disregarding such related factors as heat and wear but considering friction alone between the same surfaces with on lubricant. Under fluid-film conditions, friction is encountered. In a great range of viscosities and thus can satisfy a broad spectrum of functional requirements. Under boundary lubrication conditions , the effect of viscosity on friction becomes less significant than the chemical nature of the lubricant.Wear control. wear occurs on lubricated surfaces by abrasion, corrosion ,and solid-to-solid contact wear by providing a film that increases the distance between the sliding surfaces ,thereby lessening the damage by abrasive contaminants and surface asperities.T emperature control. Lubricants assist in controlling corrosion of the surfaces themselves is twofold. When machinery is idle, the lubricant acts as a preservative. When machinery is in use, the lubricant controls corrosion by coating lubricated parts with a protective film that may contain additives to neutralize corrosive materials. The ability of a lubricant to control corrosion is directly relatly to the thickness of the lubricant film remaining on the metal surfaces and the chermical composition of the lubricant.Other functionsLubrication are frequently used for purposes other than the reduction of friction. Some of these applications are described below.Power transmission. Lubricants are widely employed as hydraulic fluids in fluid transmission devices.Insulation. In specialized applications such as transformers and switchgear , lubricants with highdielectric constants acts as electrical insulators. For maximum insulating properties, a lubricant must be kept free of contaminants and water.Shock dampening. Lubricants act as shock-dampening fluids in energy transferring devices such as shock absorbers and around machine parts such as gears that are subjected to high intermittent loads.Sealing. Lubricating grease frequently performs the special function of forming a seal to retain lubricants or to exclude contaminants.The object of lubrication is to reduce friction ,wear , and heating of machine pars which move relative to each other. A lubricant is any substance which, when inserted between the moving surfaces, accomplishes these purposes. Most lubricants are liquids(such as mineral oil, silicone fluids, and water),but they may be solid for use in dry bearings, greases for use in rolling element bearing, or gases(such as air) for use in gas bearings. The physical and chemical interaction between the lubricant and lubricating surfaces must be understood in order to provide the machine elements with satisfactory life.The understanding of boundary lubrication is normally attributed to hardy and doubleday , who found the extrememly thin films adhering to surfaces were often sufficient to assist relative sliding. They concluded that under such circumstances the chemical composition of fluid is important, and they introduced the term “boundary lubrication”. Boundary lubrication is at the opposite end of the spectrum from hydrodynamic lubrication.Five distinct of forms of lubrication that may be defined :(a) hydrodynamic;(b)hydrostatic;(c)elastohydrodynamic (d)boundary; (e)solid film.Hydrodynamic lubrication means that the load-carrying surfaces of the bearing are separated by a relatively thick film of lubricant, so as to prevent metal contact, and that the stability thus obtained can be explained by the laws of the lubricant under pressure ,though it may be; but it does require the existence of an adequate supply at all times. The film pressure is created by the moving surfaces itself pulling the lubricant under pressure, though it maybe. The film pressure is created by the moving surface to creat the pressure necessary to separate the surfaces against the load on the bearing . hydrodynamic lubrication is also called full film ,or fluid lubrication .Hydrostatic lubrication is obtained by introducing the lubricant ,which is sometime air or water ,into the load-bearing area at a pressure high enough to separate the surface with a relatively thick film of lubricant. So ,unlike hydrodynanmic lubrication, motion of one surface relative to another is not required .Elasohydrodynamic lubrication is the phenomenon that occurs when a lubricant is introduced between surfaces which are in rolling contact, such as mating gears or rolling bearings. The mathematical explanation requires the hertzian theory of contact stress and fluid mechanics.When bearing must be operated at exetreme temperatures, a solid film lubricant such as graphite or molybdenum disulfide must be use used because the ordinary mineral oils are not satisfactory. Must research is currently being carried out in an effort, too, to find composite bearing materials with low wear rates as well as small frictional coefficients.In a journal bearing, a shaft rotates or oscillates within the bearing , and the relative motion is sliding . in an antifriction bearing, the main relative motion is rolling . a follower may either roll or slide on the cam. Gear teeth mate with each other by a combination of rolling and sliding . pistions slide within their cylinders. All these applications require lubrication to reduce friction ,wear, and heating.The field of application for journal bearing s is immense. The crankshaft and connecting rod bearings of an automotive engine must poerate for thousands of miles at high temperatures and under varying load conditions . the journal bearings used in the steam turbines of power generating station is said to have reliabilities approaching 100 percent. At the other extreme there are thousands of applications in which the loads are light and the service relatively unimportant. a simple ,easily installed bearing is required ,suing little or no lubrication. In such cases an antifriction bearing might be a poor answer because because of the cost, the close ,the radial space required ,or the increased inertial effects. Recent metallurgy developments in bearing materials , combined with increased knowledge of the lubrication process, now make it possible to design journal bearings with satisfactory lives and very good reliabilities.参考文献：1. Chambers T. L., Parkinson A. R., 1998, “Knowledge Representation and Conversion ofHybridExpert Systems.” Transactions of the ASME, v 120,pp 468-4742. Koelsch, James R., 1999, “Software boosts mold design efficiency“ Molding Systems,v57, n 3,p16-23.3. Lee, Rong-Shean, Chen, Y uh-Min, Lee, Chang-Zou,1997 “Development of a concurrentmolddesign system: A knowledge-based approach”, Computer Integrated Manufacturing Systems, v 10,n 4, p 287-3074. Steadman Sally, Pell Kynric M, 1995, “ Expert systems in engineering design: An applicationforinjection molding of plastic parts“ Journal of Intelligent Manufacturing, v6, p 347-353.5. Fernandez A., Castany J., Serraller F., Javierre C., 1997, “CAD/CAE assistant for the designofmolds and prototypes for in jection of thermoplastics “Information Technological, v 8, p 117-124.6. Douglas M Bryce, 1997, “Plastic injection molding -Material selection and product design”, v 2,pp1-48.7. Douglas M Bryce, 1997, “Plastic injection molding-Mold design fundamentals”, v2, pp 1-120 中文译文：轴承的摩擦与润滑现在看来，有很多这种情况，许多学生在被问到关于摩擦的问题时，往往都没引起足够的重视，甚至是忽视它。
机械设计外文翻译
机械设计外文翻译Mechanical DesignMechanical design is a branch of engineering that deals with the creation and development of machines and mechanical systems. It involves the application of principles and methodologies from various disciplines such as physics, materials science, and mathematics to design machines that are safe, reliable, and efficient.Mechanical design is a crucial aspect of engineering because it is responsible for creating machines that are used in a wide range of industries. From automobiles and airplanes toindustrial machinery and consumer products, mechanical design plays a vital role in the development of these machines. It requires a deep understanding of the principles of mechanics, thermodynamics, and materials science, as well as a creative and problem-solving mindset.In addition to designing machines, mechanical design also involves considerations of cost, safety, and environmental impact. Engineers must balance the performance and functionality of a machine with its cost and the impact it may have on the environment. They must also ensure that the machine is safe to use and meets all relevant regulations and standards. This often involves conducting risk assessments and performing stress andfailure analysis to identify potential issues and ensure the machine meets the required safety and quality standards.。
机械设计外文文献翻译、中英文翻译
机械设计外文文献翻译、中英文翻译unavailable。
The first step in the design process is to define the problem and XXX are defined。
the designer can begin toXXX evaluated。
and the best one is XXX。
XXX.Mechanical DesignA XXX machines include engines。
turbines。
vehicles。
hoists。
printing presses。
washing machines。
and XXX and methods of design that apply to XXXXXX。
cams。
valves。
vessels。
and mixers.Design ProcessThe design process begins with a real need。
Existing apparatus may require XXX。
efficiency。
weight。
speed。
or cost。
while new apparatus may be XXX。
To start。
the designer must define the problem and XXX。
ideas and concepts are generated。
evaluated。
and refined until the best one is XXX。
XXX.XXX。
assembly。
XXX.During the preliminary design stage。
it is important to allow design XXX if some ideas may seem impractical。
they can be corrected early on in the design process。
机械工程外文翻译
外文资料原文及译文学院：机电工程学院专业：机械设计制造及其自动化班级：学号：姓名：Mechanical engineering1.The porfile of mechanical engineeringEngingeering is a branch of mechanical engineerig,itstudies mechanical and power generation especially power and movement.2.The history of mechanical engineering18th century later periods,the steam engine invention hasprovided a main power fountainhead for the industrialrevolution,enormously impelled each kind of mechznicalbiting.Thus,an important branch of a new Engineering –separated from the civil engineering tools and machines on thebranch-developed together with Birmingham and the establishment of the Associantion of Mechanical Engineers in1847 had been officially recognized.The mechanicalengineering already mainly used in by trial and error methodmechanic application technological development intoprofessional engineer the scientific method of which in theresearch,the design and the realm of production used .From themost broad perspective,the demend continuously to enhance theefficiencey of mechanical engineers improve the quality of work,and asked him to accept the history of the high degreeof education and training.Machine operation to stress not onlyeconomic but also infrastructure costs to an absolute minimun.3.The field of mechanical engineeringThe commodity machinery development in the develop country,in the high level material life very great degree is decided each kind of which can realize in the mechanical engineering.Mechanical engineers unceasingly will invent the machine next life to produce the commodity,unceasingly will develop the accuracy and the complexity more and more high machine tools produces the machine.The main clues of the mechanical development is:In order to enhance the excellent in quality and reasonable in price produce to increase the precision as well as to reduce the production cost.This three requirements promoted the complex control system development.The most successful machine manufacture is its machine and the control system close fusion,whether such control system is essentially mechanical or electronic.The modernized car engin production transmission line(conveyer belt)is a series of complex productions craft mechanization very good example.The people are in the process of development in order to enable further automation of the production machinery ,the use of a computer to store and handle large volumes of data,the data is a multifunctional machine toolsnecessary for the production of spare parts.One of the objectives is to fully automated production workshop,three rotation,but only one officer per day to operate.The development of production for mechanical machinery must have adequate power supply.Steam engine first provided the heat to generate power using practical methods in the old human,wind and hydropower,an increase of engin .New mechanical engineering industry is one of the challenges faced by the initial increase thermal effciency and power,which is as big steam turbine and the development of joint steam boilers basically achieved.20th century,turbine generators to provide impetus has been sustained and rapid growth,while thermal efficiency is steady growth,and large power plants per kW capital consumption is also declining.Finally,mechanical engineers have nuclear energy.This requires the application of nuclear energy particularly high reliability and security, which requires solving many new rge power plants and the nuclear power plant control systems have become highly complex electroonics,fluid,electricity,water and mechanical parts networks All in all areas related to the mechanical engineers.Small internal combustion engine,both to the type (petrol and diesel machines)or rotary-type(gas turbines andMong Kerr machine),as well as their broad application in the field of transport should also due to mechanical enginerrs.Throughout the transport,both in the air and space,or in the terrestrial and marine,mechanial engineers created a variety of equipment and power devices to their increasing cooperation with electrical engineers,especially in the development of appropration control systems.Mechanical engineers in the development of military weapons technology and civil war ,needs a similar,though its purpose is to enhance rather than destroy their productivity.However.War needs a lot of resources to make the area of techonlogy,many have a far-reaching development in peacetime efficiency.Jet aircraft and nuclear reactors are well known examples.The Biological engineering,mechanical engineering biotechnology is a relatively new and different areas,it provides for the replacement of the machine or increase the body functions as well as for medical equipment.Artficial limbs have been developed and have such a strong movement and touch response function of the human body.In the development of artificial organ transplant is rapid,complex cardiac machines and similar equipment to enable increasingly complex surgery,and injuries and ill patients life functions can besustained.Some enviromental control mechanical engineers through the initial efforts to drainage or irrigation pumping to the land and to mine and ventilation to control the human environment.Modern refrigeration and air-conditioning plant commonaly used reverse heat engine,where the heat from the engine from cold places to more external heat.Many mechanical engineering products,as well as other leading technology development city have side effects on the environment,producing noise,water and air pollution caused,destroyed land and landscape.Improve productivity and diver too fast in the commodity,that the renewable natural forces keep pace.For mechanical engineers and others,environmental control is rapidly developing area,which includes a possible development and production of small quantities of pollutants machine sequnce,and the development of new equipment and teachnology has been to reduce and eliminate pollution.4.The role of mechanical engineeringThere are four generic mechanical engineers in common to the above all domains function.The 1st function is the understanding and the research mechanical science foundation.It includes the power and movement of therelationship dynamics For example,in the vibration and movement of the relationship;Automatic control;Study of the various forms of heart,energy,power relations between the thermodynamic;Fluidflows; Heat transfer; Lubricant;And material properties.The 2nd function will be conducts the research,the desing and the development,this function in turn attempts to carry on the essential change to satisfy current and the future needs.This not only calls for a clear understanding of mechanical science,and have to break down into basic elements of a complex system capacity.But also the need for synthetic and innovative inventions.The 3rd function is produces the product and the power,include plan,operation and maintenance.Its goal lies in the maintenance either enhances the enterprise or the organization longer-tern and survivabilaty prestige at the same time,produces the greatest value by the least investments and the consumption.The 4th function is mechanical engineer’s coordinated function,including the management,the consultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use the science for a long time the method,but is not traditional orthe intuition method tendency,this is a mechanical engineering skill aspect which unceasingly grows.These new rationalization means typical names include:The operations research,the engineering economics,the logical law problem analysis(is called PABLA) However,creativity is not rationalization.As in other areas,in mechanical engineering, to take unexpected and important way to bring about a new capacity,still has a personal,marked characteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,such as:the instrument and the measuring appliance in very many situations,the machine design must use the knowledge of discipline the and so on mathematics,materials science and mechanics.Mechanical engineering desgin includeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnical engineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Design stages.The entire desgin process from start to finish,in the process,a demand that is designed for it and decided to do the start.After a lot of repetition,thefinal meet this demand by the end of the design procees and the plan.Design considerations.Sometimes in a system is to decide which parts needs intensity parts of geometric shapes and size an important factor in this context that we must consider that the intensity is an important factor in the design.When we use expression design considerations,we design parts that may affect the entire system design features.In the circumstances specified in the design,usually for a series of such functions must be taken into account.Howeever,to correct purposes,we should recognize that,in many cases the design of important design considerations are not calculated or test can determine the components or systems.Especially students,wheen in need to make important decisions in the design and conduct of any operation that can not be the case,they are often confused.These are not special,they occur every day,imagine,for example,a medical laboratory in the mechanical design,from marketing perspective,people have high expectations from the strength and relevance of impression.Thick,and heavy parts installed together:to produce a solid impression machines.And sometimes machinery and spare parts from the design style is the point and not the other point of view.Our purpose is to make those you do notbe misled to believe that every design decision will need reasonable mathematical methods.Manufacturing refers to the raw meterials into finished products in the enterprise.Create three distinct phases.They are:input,processing exprot.The first phase includes the production of all products in line with market needs essential.First there must be the demand for the product,the necessary materials,while also needs such as energy,time,human knowledge and technology resourcess . Finall,the need for funds to obtain all the other resources. Lose one stage after the second phase of the resources of the processes to be distributed.Processing of raw materials into finished products of these processes.To complete the design,based on the design,and then develop plans.Plan implemented through various production processes.Management of resources and processes to ensure efficiency and productivity.For example,we must carefully manage resources to ensure proper use of funds.Finally,people are talking about the product market was cast.Stage is the final stage of exporting finished or stage.Once finished just purchased,it must be delivered to the users.According to product performance,installation and may have to conduct furtherdebugging in addition,some products,especially those very complex products User training is necessary.6.The processes of materials and maunfacturingHere said engineering materials into two main categories:metals and non-ferrous,high-performance alloys and power metals.Non-metallic futher divided into plastice,synthetic rubber,composite materials and ceramics.It said the production proccess is divided into several major process,includingshape,forging,casting/ founding,heat treatment,fixed/connections ,measurement/ quality control and materal cutting.These processes can be further divide into each other’s craft.Various stages of the development of the manufacturing industry Over the years,the manufacturing process has four distinct stages of development, despite the overlap.These stages are:The first phase is artisanal,the second Phase is mechanization.The third phase is automation the forth Phase is integrated.When mankind initial processing of raw materials into finished products will be,they use manual processes.Each with their hands and what are the tools manuslly produced.This is totally integrated production take shape.A person needs indentification,collection materials,the design of a productto meet that demand,the production of such products and use it.From beginning to end,everything is focused on doing the work of the human ter in the industrial revolution introduced mechanized production process,people began to use machines to complete the work accomplished previously manual. This led to the specialization.Specialization in turn reduce the manufacture of integrated factors.In this stage of development,manufacturing workers can see their production as a whole represent a specific piece of the part of the production process.One can not say that their work is how to cope with the entire production process,or how they were loaded onto a production of parts finished.Development of manufacting processes is the next phase of the selection process automation.This is a computer-controlled machinery and processes.At this stage,automation island began to emerge in the workshop lane.Each island represents a clear production process or a group of processes.Although these automated isolated island within the island did raise the productivity of indivdual processes,but the overall productivity are often not change.This is because the island is not caught in other automated production process middle,but not synchronous with them .The ultimate result is the efficient working fast parkedthrough automated processes,but is part of the stagnation in wages down,causing bottlenecks.To better understand this problem,you can imagine the traffic in the peak driving a red light from the red Service Department to the next scene. Occasionally you will find a lot less cars,more than being slow-moving vehicles,but the results can be found by the next red light Brance.In short you real effect was to accelerate the speed of a red Department obstruction offset.If you and other drivers can change your speed and red light simultaneously.Will advance faster.Then,all cars will be consistent,sommth operation,the final everyone forward faster.In the workshop where the demand for stable synchronization of streamlined production,and promoted integration of manufacturing development.This is a still evolving technology.Fully integrated in the circumstances,is a computer-controllrd machinery and processing.integrated is completed through computer.For example in the preceding paragraph simulation problems,the computer will allow all road vehicles compatible with the change in red.So that everyone can steady traffic.Scientific analysis of movement,timing and mechanics of the disciplines is that it is composed of two pater:staticsand dynamics.Statics analyzed static system that is in the system,the time is not taken into account,research and analysis over time and dynamics of the system change.Dynameics from the two componets.Euler in 1775 will be the first time two different branches: Rigid body movement studies can conveniently divided into two parts:geometric and mechanics.The first part is without taking into account the reasons for the downward movement study rigid body from a designated location to another point of the movement,and must use the formula to reflect the actual,the formula would determine the rigid body every point position. Therefore,this study only on the geometry and,more specifically,on the entities from excision.Obviously,the first part of the school and was part of a mechanical separation from the principles of dynamics to study movement,which is more than the two parts together into a lot easier.Dynamics of the two parts are subsequently divided into two separate disciplines,kinematic and dynamics,a study of movement and the movement strength.Therefore,the primary issue is the design of mechanical systems understand its kinematic.Kinematic studies movement,rather than a study of its impact.In a more precise kinematic studies position,displacement,rotation,speed,velocity and acceleration of disciplines,for esample,or planets orbiting research campaing is a paradigm.In the above quotation content should be pay attention that the content of the Euler dynamics into kinematic and rigid body dynamics is based on the assumption that they are based on research.In this very important basis to allow for the treatment of two separate disciplines.For soft body,soft body shape and even their own soft objects in the campaign depends on the role of power in their possession.In such cases,should also study the power and movement,and therefore to a large extent the analysis of the increased complexity.Fortunately, despite the real machine parts may be involved are more or less the design of machines,usually with heavy material designed to bend down to the lowest parts.Therefore,when the kinematic analysis of the performance of machines,it is often assumed that bend is negligible,spare parts are hard,but when the load is known,in the end analysis engine,re-engineering parts to confirm this assnmption.机械工程1.机械工程简介机械工程是工程学的一个分支，它研究机械和动力的产，尤其是力和动力。
机械专业毕业设计外文翻译1
本科毕业设计（本科毕业论文）外文文献及译文文献、资料题目：High-rise Tower Crane designed文献、资料来源：期刊（著作、网络等）文献、资料发表（出版）日期：2000.3.25院（部）：机电工程学院专业：机电工程及自动化High-rise Tower Crane designed under Turbulent Winds At present, construction of tower cranes is an important transport operations lifting equipment, tower crane accident the people's livelihood, major hazards, and is currently a large number of tower crane drivers although there are job permits, due to the lack of means to monitor and review the actual work of a serious violation . Strengthen the inspection and assessment is very important. Tower crane tipping the cause of the accident can be divided into two aspects: on the one hand, as a result of the management of tower cranes in place, illegal operation, illegal overloading inclined cable-stayed suspended widespread phenomenon; Second, because of the tower crane safety can not be found in time For example,Took place in the tower crane foundation tilt, micro-cracks appear critical weld, bolts loosening the case of failure to make timely inspection, maintenance, resulting in the continued use of tower cranes in the process of further deterioration of the potential defect, eventually leading to the tower crane tipping. The current limit of tower crane and the black box and can not be found to connect slewing tower and high-strength bolts loosening tightened after the phenomenon is not timely, not tower verticality of the axis line of the lateral-line real-time measurement, do not have to fight the anti-rotation vehicles, lifting bodies plummeted Meng Fang, hook hoists inclined cable is a timely reminder and record of the function, the wind can not be contained in the state of suspended operation to prevent tipping on the necessary tips on site there is a general phenomenon of the overloaded overturning of the whole security risks can not be accurately given a reminder and so on, all of which the lease on the tower crane, use, management problems,Through the use of tower crane anti-tipping monitor to be resolved. Tower crane anti-tipping Monitor is a new high-tech security monitoring equipment, and its principle for the use of machine vision technology and image processing technology to achieve the measurement of the tilt tower, tower crane on the work of state or non-working state of a variety of reasons angle of the tower caused by the critical state to achieve the alarm, prompt drivers to stop illegal operation, a computer chip at the same time on the work of the state of tower crane be recorded. Tower crane at least 1 day overload condition occurs, a maximum number of days to reach 23 overloading, the driver to operate the process of playing the anti-car, stop hanging urgency, such as cable-stayed suspended oblique phenomenon often, after verification and education, to avoid the possible occurrence of fatal accidents. Wind conditions in the anti-tipping is particularly important, tower cranes sometimes connected with the pin hole and pin do not meet design requirements, to connect high-strength bolts are not loose in time after the tightening of the phenomenon, through timely maintenance in time after the tightening of the phenomenon, through timely maintenance and remedial measures to ensure that the safe and reliable construction progress. Reduced lateral line tower vertical axis measuring the number of degrees,Observation tower angle driver to go to work and organize the data once a month to ensure that the lateral body axis vertical line to meet the requirements, do not have to every time and professionals must be completed by Theodolite tower vertical axismeasuring the lateral line, simplified the management link. Data logging function to ensure that responsibility for the accident that the scientific nature to improve the management of data records for the tower crane tower crane life prediction and diagnosis of steel structures intact state data provides a basis for scientific management and proactive prevention of possible accidents, the most important thing is, if the joint use of the black box can be easily and realistically meet the current provisions of the country's related industries. Tower crane safety management at the scene of great importance occurred in the construction process should be to repair damaged steel, usually have to do a good job in the steel tower crane maintenance work and found that damage to steel structures, we must rule out potential causes of accidents, to ensure safety in production carried out smoothly. Tower crane in the building construction has become essential to the construction of mechanical equipment, tower crane at the construction site in the management of safety in production is extremely important. A long time, people in the maintenance of tower crane, only to drive attention to the conservation and electrical equipment at the expense of inspection and repair of steel structures, to bring all kinds of construction accidents.Conclusion: The tower crane anti-tipping trial monitor to eliminate potential causes of accidents to provide accurate and timely information, the tower crane to ensure the smooth development of the leasing business, the decision is correct, and should further strengthen and standardize the use of the environment (including new staff training and development of data processing system, etc.).The first construction cranes were probably invented by the Ancient Greeks and were powered by men or beasts of burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of human treadwheels, permitting the lifting of heavier weights. In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction – some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron and steel took over with the coming of the Industrial Revolution.For many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first 'mechanical' power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still utilised where the provision of power would be uneconomic.Cranes exist in an enormous variety of forms – each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes,used for constructing high buildings, and the largest floating cranes, used to build oil rigs and salvage sunken ships.This article also covers lifting machines that do not strictly fit the above definition of a crane, but are generally known as cranes, such as stacker cranes and loader cranes.The crane for lifting heavy loads was invented by the Ancient Greeks in the late 6th century BC. The archaeological record shows that no later than c.515 BC distinctive cuttings for both lifting tongs and lewis irons begin to appear on stone blocks of Greek temples. Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity, they are regarded by archaeologists as the positive evidence required for the existence of the crane.The introduction of the winch and pulley hoist soon lead to a widespread replacement of ramps as the main means of vertical motion. For the next two hundred years, Greek building sites witnessed a sharp drop in the weights handled, as the new lifting technique made the use of several smaller stones more practical than of fewer larger ones. In contrast to the archaic period with its tendency to ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned in favour of using several column drums.Although the exact circumstances of the shift from the ramp to the crane technology remain unclear, it has been argued that the volatile social and political conditions of Greece were more suitable to the employment of small, professional construction teams than of large bodies of unskilled labour, making the crane more preferable to the Greek polis than the more labour-intensive ramp which had been the norm in the autocratic societies of Egypt or Assyria.The first unequivocal literary evidence for the existence of the compound pulley system appears in the Mechanical Problems (Mech. 18, 853a32-853b13) attributed to Aristotle (384-322 BC), but perhaps composed at a slightly later date. Around the same time, block sizes at Greek temples began to match their archaic predecessors again, indicating that the more sophisticated compound pulley must have found its way to Greek construction sites by then.During the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire. The earliest reference to a treadwheel (magna rota) reappears in archival literature in France about 1225, followed by an illuminated depiction in a manuscript of probably also French origin dating to 1240. In navigation, the earliest uses of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Brugge in 1288 and Hamburg in 1291, while in England the treadwheel is not recorded before 1331.Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. Typical areas of application were harbors, mines, and, in particular, building sites where the treadwheel crane played a pivotal role in the construction of the lofty Gothic cathedrals. Nevertheless, both archival and pictorial sources of the time suggest that newly introduced machines like treadwheels or wheelbarrows did not completely replace more labor-intensive methods like ladders, hods and handbarrows. Rather, old and new machinery continued to coexist on medieval construction sites and harbors.Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes, cranks and by the 15th century also by windlasses shaped like a ship's wheel. To smooth out irregularities of impulse and get over 'dead-spots' in the lifting process flywheels are known to be in use as early as 1123.The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Alternatively, the medieval treadwheel may represent a deliberate reinvention of its Roman counterpart drawn from Vitruvius' De architectura which was available in many monastic libraries. Its reintroduction may have been inspired, as well, by the observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities.In contrast to modern cranes, medieval cranes and hoists - much like their counterparts in Greece and Rome - were primarily capable of a vertical lift, and not used to move loads for a considerable distance horizontally as well. Accordingly, lifting work was organized at the workplace in a different way than today. In building construction, for example, it is assumed that the crane lifted the stone blocks either from the bottom directly into place, or from a place opposite the centre of the wall from where it could deliver the blocks for two teams working at each end of the wall. Additionally, the crane master who usually gave orders at the treadwheel workers from outside the crane was able to manipulate the movement laterally by a small rope attached to the load. Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340. While ashlar blocks were directly lifted by sling, lewis or devil's clamp (German Teufelskralle), other objects were placed before in containers like pallets, baskets, wooden boxes or barrels.It is noteworthy that medieval cranes rarely featured ratchets or brakes to forestall the load from running backward.[25] This curious absence is explained by the high friction force exercised by medieval treadwheels which normally prevented the wheel from accelerating beyond control.目前，塔式起重机是建筑工程进行起重运输作业的重要设备，塔机事故关系国计民生、危害重大，而目前众多的塔机司机虽然有上岗证，由于缺少监督和复核手段，实际工作中违规严重。
机械专业毕业设计外文翻译--机械传动系统介绍
Transmission System introducedThe important position of the wheel gear and shaft can’t falter in traditional machine and modern machines. The wheel gear and shafts mainly install the direction that delivers the dint at the principal axis box. The passing to process to make them can is divided into many model numbers, used for many situations respectively. so we must be the multilayers to the understanding of the wheel gear and shaft in many ways.In the force analysis of spur gears, the forces are assumed to act in a single plane. We shall study gears in which the forces have three dimensions. The reason for this, in the case of helical gears, is that the teeth are not parallel to the axis of rotation. And in the case of bevel gears, the rotational axes are not parallel to each other. There are also other reasons, as we shall learn.Helical gears are used to transmit motion between parallel shafts. The helix angle is the same on each gear, but one gear must have a right-hand helix and the other a left-hand helix. The shape of the tooth is an involute helicoid. If a piece of paper cut in the shape of a parallelogram is wrapped around a cylinder, the angular edge of the paper becomes a helix. If we unwind this paper, each point on the angular edge generates an involute curve. The surface obtained when every point on the edge generates an involute is called an involute helicoids.The initial contact of spur-gear teeth is a line extending all the way across the face of the tooth. The initial contact of helical gear teeth is a point, which changes into a line as line as the teeth come into more engagement. In spur gears the line of contact is parallel to the axis of the rotation; in helical gears, the line is diagonal across the face of the tooth. It is this gradual of the teeth and the smooth transfer of load from one tooth to another, which give helical gears the ability to transmit heavy loads at high speeds. Helical gears subject the shaft bearings to both radial and thrust loads. When the thrust loads become high or are objectionable for other reasons, it may be desirable to use double helical gears. A double helical gear (herringbone) is equivalent to two helical gears of opposite hand, mounted side by side on the same shaft. They develop opposite thrust reactions and thus cancel out the thrust load. When two or more single helical gears are mounted on the same shaft, the hand of the gears should be selected so as to produce the minimum thrust load.Crossed-helical, or spiral, gears are those in which the shaft centerlines are neither parallel nor interesting. The teeth of crossed-helical fears have point contact with each other which changes to line contact as the gears wear in. for this reason they will carry out very small loads and are mainly for instrumental applications, and are definitely not recommended for use in the transmission of power. There is on difference between a crossed helical gear and a helical gear until they are mounted in mesh with each other. They are manufactured in the same way. A pair of meshed crossed helical gears usually have the same hand; that is, a right-hand driver goes with a right-hand driven. In the design of crossed-helical gears, the minimum sliding velocity is obtained when the helix angle are equal. However, when the helix angle are not equal, the gear with the larger helix angle should be used as the driver if both gears have the same hand.Worm gears are similar to crossed helical gears. The pinion or worm has a small number of teeth, usually one to four, and since they completely wrap around the pitch cylinder they are called threads. Its mating gear is called a worm gear, which is not a true helical gear. A worm and worm gear are used to provide a high angular-velocity reduction between nonintersecting shafts which are usually at right angle. The worm gear is not a helical gear because its face is made concave to fit the curvature of the worm in order to provide line contact instead of point contact. However, a disadvantage of worm gearing is the high sliding velocities across the teeth, the same as with crossed helical gears.Worm gearing are either single or double enveloping. A single-enveloping gearing is one in which the gear wraps around or partially encloses the worm. A gearing in which each element partially encloses the other is, of course, a double-enveloping worm gearing. The important difference between the two is that area contact exists between the teeth of double-enveloping gears while only line contact between those of single-enveloping gears. The worm and worm gear of a set have the same hand of helix as for crossed helical gears, but the helix angles are usually quite different. The helix angle on the worm is generally quite large, and that on the gear very small. Because of this, it is usual to specify the lead angle on the worm, which is the complement of the worm helix angle, and the helix angle on the gear; the two angles ate equal for a 90-deg. Shaft angle.When gears are to be used to transmit motion between intersecting shaft, some ofbevel gear is required. Although bevel gear are usually made for a shaft angle of 90 deg. They may be produced for almost any shaft angle. The teeth may be cast, milled, or generated. Only the generated teeth may be classed as accurate. In a typical bevel gear mounting, one of the gear is often mounted outboard of the bearing this means that shaft deflection can be more pronounced and have a greater effect in the contact of teeth. Another difficulty, which occurs in predicting the stress in bevel-gear teeth, is the fact the teeth are tapered.Straight bevel gears are easy to design and simple to manufacture and give very good results in service if they are mounted accurately and positively. As in the case of squrgears, however, they become noisy at higher values of the pitch-line velocity. In these cases it is often good design practice to go to the spiral bevel gear, which is the bevel counterpart of the helical gear. As in the case of helical gears, spiral bevel gears give a much smoother tooth action than straight bevel gears, and hence are useful where high speed are encountered.It is frequently desirable, as in the case of automotive differential applications, to have gearing similar to bevel gears but with the shaft offset Such gears are called hypoid gears because their pitch surfaces are hyperboloids of revolution The tooth action between such gears is a combination of rolling and has much in common with that of worm gears.A shaft is a rotating or stationary member usually of circular cross section, having mounted upon it such elementsas gears pulleys flywheels, cranks sprockets and other power-transmission elements Shaft may be subjected to bending tension compression or torsional loads acting singly or in combination with one another .When they are combined one may expect to find both static and fatigue strength to be important design considerations since a single shaft may be subjected to static stresses completely reversed, and repeated stresses, all acting at the same timeThe word “shaft” covers numerous wariations, such as axles and spindles. Anaxle is a shaft, wither stationary or rotating nor subjected to torsion load. Ashirt rotating shaft is often called a spindle.When either the lateral or the tosional deflection of shaft must be held to close limits, the shaft must be sized on the basis of deflection before analyzing the stresses The reasonfor this is that if the shift is made stiff enough so that the deflection is not too large, it is probable that the resulting stresses will be safe. But by no means should the designer assume that they are within acceptable limits. Whenever possible the power-transmission elements such as gears or pullets, should be located close to the supporting bearings. This reduces the bending moment, and hence the deflection and bending stress.Although the von Mises-Hencky-Goodman method is difficult to use in design of shaft, it probably come closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaft-design problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heat-treatment, and surface finish and whether or not shot peening is necessary in order to achieve the required life and reliability.Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake, two inertias I1and I2 traveling at the respective angular velocities W1 and W2, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake. Slippage occurs because the two elements are running at different speeds and energy is dissipated during actuation, resulting in a temperature rise. In analyzing the performance of these devices we shall be interested in the actuating force, the torque transmitted, the energy loss and the temperature rise. The torque transmitted is related to the actuating force, the coefficient of friction, and the geometry of the clutch or brake. This is problem in static, which will have to be studied separately for each geometric configuration. However, temperature rise is related to energy loss and can be studied without regard to the type of brake or clutch because the geometry of interest is the hear-dissipating surfaces. The various types of clutches and brakes may be classified as fallows:Rim type with internally expanding shoesRim type with internally contracting shoesBand typeDisk or axial typeCone typeMiscellaneous typeThe analysis of all type of friction clutches and brakes use the same general procedure. The following step are necessary:1. Assume or determine the distribution of pressure on the frictionalsurfaces.2. Find a relation between the maximum pressure and the pressure at any point3. apply the condition of statical equilibrium to find (a) the actuating force, (b) the torque, and (c) the support reactions.Miscellaneous clutches include several type, such as the positive-contact clutches, overload-release clutches, overrunning clutches, magnetic fluid clutches, and others.A positive-contact clutch consists of a shift lever and two jaws. The greatest differences between the various types of positive clutches are concerned with the design of the jaws. To provide a longer period of time for shift action during engagement, the jaws may be ratchet-shaped, or gear-tooth-shaped. Sometimes a great many teeth or jaws re used, and they may be cut either circumferentially, so that they engage by cylindrical mating, or on the faces of the mating elements.Although positive clutches are not used to the extent the frictional-contact type, they do have important applications where synchronous operation is required.Devices such as linear driver or motor-operated screw drivers must run to definite limit and then come to a stop. An over load-release rype of clutch is required for these applications. These clutches are usually spring-loaded so as to release at a predetermined toque. The clicking sound which is heard when the overload point is reached is considered to be a desirable signal.An overrunning clutch or coupling permits the driven member of a machine to “freewheel” or “overrun” because the driver is stopped or because another source of power increase the speed of the driven. This type of clutch usually uses rollers or balls mounted between an outer sleeve and an inner member having flats machined around the periphery. Driving action is obtained by wedding the rollers between the sleeve and the flats. The clutch is therefore equivalent to a pawl and ratchet with an infinite number of teeth.Magnetic fluid clutch or brake is a relatively new development which has two parallel magnetic plates. Between these plates is a lubricated magnetic powder mixture. An electromagnetic coil is inserted somewhere in the magnetic circuit. Bu varying the excitation to this coil, the shearing strength of the magnetic fluid mixture may be accurately controlled. Thus any condition from a full slip to a frozen lockup may be obtained.机械传动系统介绍在传统机械和现代机械中齿轮和轴的重要地位是不可动摇的。
机械毕业设计英文外文翻译255计算机与制造业
附录2英语原文The Computer and ManufacturingComputer Aided DesignThe computer is bringing manufacturing into the Information Age. This new tool, a long familiar one in business and management operations, is moving into the factory, and its advent is changing manufacturing as certainly as the steam engine changed it 100 years ago.The basic metal working processes are not likely to change fundamentally, but their organization and control definitely will.IN one respect, manufacturing could be said to be coming full circle. The first manufacturing could was a cottage industry: the designer was also the manufacturer, conceiving and fabricating products one at a time. Eventually, the concept of the interchangeability of parts was developed, production was separated into specialized functions, and identical parts were produced thousands at a time.Today, although the designer and manufacturer may not become one again, the functions are being drawn close in the movement toward an integrated manufacturing system,It is perhaps ironic that, at a time when the market demand a high degreed of product diversification, the necessity for increasing productivity and reducing costs is driving manufacturing toward integration into a coherent system, a continuous process in which parts do not spend as much as 95% of production time being moved around or waiting to be worked on.The computer is the key to each of these twin requirements. It is the only tool that can provide the quick reflexes, the flexibility and speed, to meet a diversified market. And it is the only tool that enables the detailed analysis and the accessibility of accurate data necessary for the integration of the manufacturing system.It may well be that, in the future, the computer may be essential to a company’s survival. Many of today’s businesses will fade away to be replaced by more-productive combinations. Such more-productive combinations aresuper-quality, super-productivity plants. The goal is to design and operate a plant that would produce 100% satisfactory parts with good productivity.A sophisticated, competitive world is requiring that manufacturing begin to settle for more, to become itself sophisticated, To meet competition, for example, a company will have to meet the somewhat conflicting demands for greater product diversification, higher quality, improved productivity, and low prices.The company that seeks to meet these demands will need a sophisticated tool, one that will allow it to respond quickly to customer needs while getting the most out of its manufacturing resources.The computer is that tool.Becoming a “super-quality, super-productivity” plant requires the integration of an extremely complex system. This can be accomplished only when all elements of manufacturing—design, fabrication and assembly, quality assurance, management, materials handling—are computer integrated.In product design, for example, interactive computer-aided-design (CAD) systems allow the drawing and analysis tasks to be performed in a fraction of the time previously required and with greater accuracy. And programs for prototype testing and evaluation further speed the design process.In manufacturing planning, computer-aided process planning permits the selection, from thousands of possible sequences schedules, of the optimum process.On the shop floor, distributed intelligence in the form of microprocessors controls machines, runs automated loading and unloading equipment, and collects data on current shop conditions.But such isolated revolutions are not enough. What is needed is a totally automated system, linked by common software from front door to back.The benefits range throughout the system. Essentially, computer integration provides widely and instantaneously available, accurate information, improving communication between departments, permitting tighter control, and generally enhancing the overall quality and efficiency of the entire system.Improved communication can mean, for example, designs that are more producible. The NC programmer and the tool designer have a chance to influence the product designer, and vice versa.Engineering changes, thus, can be reduced, and those that are required can be handled more efficiently. Not only does the computer permit them to be specifiedmore quickly, but it also alerts subsequent users of the data to the fact that a change has been made.The instantaneous updating of production-control data permits better planning and more0effective scheduling. Expensive equipment, therefore, is used more productively, and parts move more efficiently through production, reducing work-in-process costs.Product quality, too, can be improved. Not only are more-accurate designs produced, for example, but the use of design data by the quality-assurance department helps eliminate errors due to misunderstandings.People are enabled to do their jobs better. By eliminating tedious calculations and paperwork—not to mention time wasted searching for information—the computer not only allows workers to be more productive but also frees them to do what only human beings can do: think creatively.Computer integration may also lure new people into manufacturing. People are attracted because they want to work in a modern, technologically sophisticated environment.In manufacturing engineering, CAD/CAM decreases tool-design. NC-programming, and planning times while speeding the response rate, which will eventually permit in-house staff to perform work that is currently being contracted out.According to the Tool & Manufacturing Engineers Handbook, process planning is the systematic determination of the methods by which a product is to be manufactured economically and competitively. It essentially involves selection, calculation, and documentation. Processes, machines, tools, and sequences must be selected. Such factors as feeds, speeds, tolerances, dimensions, and costs must be calculated. Finally, documents in the form of setup instructions, work instructions, illustrated process sheets, and routings must be prepared. Process planning is an intermediate stage between designing and manufacturing the product. But how well does it bridge design and manufacturing?Most manufacturing engineers would agree that, if ten different planners were asked to develop a process plan for the same part, they would probably come up with ten different plans. Obviously, all these plans cannot reflect the most efficient manufacturing methods, and, in fact, there is no guarantee that any one of them will constitute the optimum methods for manufacturing the part.What may be even more disturbing is that a process plan developed for a part during a current manufacturing program may be quite different manufacturing program and it may never be used again for the same or similar part during a previous similar part. That represents a lot of wasted effort and produces a great many inconsistencies in routing, tooling, labor requirements, costing, and possibly even purchase requirements.Of course, process plans should not necessarily remain static. As lot sizes change and new technology, equipment, and processes become available, the most effective way to manufacture a particular part also changes, and those changes should be reflected in current process plans released to the shop.A planner must manage and retrieve a great deal of data and many documents, including established standards, machine ability data, machine specifications, tooling inventories, stock availability, and existing process plans. This is primarily an information-handling job, and the computer is an ideal companion.There is another advantage to using computers to help with process planning. Because the task involves many interrelated activities, determining the optimum plan requires many iterations. Since computers can readily perform vast numbers of comparisons, many more alternative plans can be explored than would be possible manually.A third advantage in the use of computer-aided process planning is uniformity.Several specific benefits can be expected from the adoption of computer-aided process-planning techniques:● Reduced clerical effort in preparation of instructions.● Fewer calculation errors due to human error.● Fewer oversights in logic or instructions because of the prompting capability available with interactive computer programs.● Immediate access to up-to-date information from a central database.● Consistent information, because every planner accesses the same database.● Faster response to changes requested by engineering of other operating departments.● Automatic use of the latest revision of a part drawing.● More-detailed, more-uniform process-plan statements produced by word processing techniques.● More-effective use of inventories of tools, gages, and fixtures and aconcomitant reduction in the variety of those items.● Better communication with shop personnel because plans can be more specifically tailored to a particular task and presented in unambiguous, proven language.● Better information for production planning, including cutter-life, forecasting, materials-requirements planning, scheduling, and inventory control.Most important for CIM, computer-aided process planning produces machine-readable data instead of hand written plans. Such data can readily be transferred to other systems within the CIM hierarchy for use in planning.There are basically two approaches to computer-aided process planning: variant and generative.In the variant approach, a set of standard process plans is established for all the parts families that have been identified through group technology. The standard plans are stored in computer memory and retrieved for new parts according to their family identification. Again, GT helps to place the new part in an appropriate family. The standard plan is then edited to suit the specific requirements of a particular job.In the generative approach, an attempt is made to synthesize each individual plan using appropriate algorithms that define the various technological decisions that must be made in the course of manufacturing. In a truly generative process-planning system, the sequence of operations, as well as all the manufacturing-process parameters, would be automatically established without reference to prior plans. In its ultimate realization, such an approach would be universally applicable: present any plan to the system, and the computer produces the optimum process plan.No such system exists, however. So called generative process-planning system—and probably for the foreseeable future—are still specialized systems developed for a specific operation or a particular type of manufacturing process. The logic is based on a combination of past practice and basic technology.Computer Aided ManufacturingNumerical ControlNumerical control can be defined as a form of programmable automation in which the process is controlled by numbers,letters,and symbols.In NC, thenumbersform a program of instructions designed for a particular workpart or job. When the job changes, the program of instructions is changed .This capability to change the program for each new job is what gives NC its flexibility, It is much easier to write new programs than to make major change in the production equipment.NC equipment is used in all areas of metal parts fabrication and comprises roughly 15% of the modern machine tools in industry today. Since numerically controlled machines are considerably more expensive than their conventional counterparts, the asset value of industrial NC machine tools is proportionally much larger than their numbers. Equipment utilizing numerical control has been designed to perform such diverse operations as drilling, milllng~; ~r~j, gtindlng, :sheetmetal pres~orkingi spot welding, arc welding, riveting, assembly, drafting, inspection, and parts handling. And this is by no means a complete list. Numerical control should be considered as a possible mode of controlling the operation for any production situation possessing the following characteristics:I, .Similar workparts in terms of raw material(e. g., metal stock for machining)2. The workparts are produced in various sizes and geometries.3. The workparts are produced in batches of small to medium-sized quantities.4. A sequence of similar processing steps is required to complete the operation oneach workpiece.Many machining jobs meet these conditions. The machined workparts are metal,they are specified in many differentsizes and shapes, and most machined parts produced in industry today are made in small to medium-size lot sizes.To produce each part,a sequence of drilling operations may be required, or a series of turning or milling operations. The suitability of NC for these kinds of jobs is the reason for the tremendous growth of numerical control in the metalworking industry over the last 25 years.Basic Components of an NC systemAn operational numerical control system consists of the following three basic components:1.Program of instructions.2.Controller unit, also called machine control unit (MCU)3.Machine tool or other controlled processThe program of instructions serves as the input to the controller unit , which inturn commands the machine tool or other process to be controlled.Program of instructionsThe program of instructions is the detailed step-by-step set of directions which tell the machine tool what to do. It is coded in numerical or symbolic form on some type of input medium that can be interpreted by the controller unit. The most common input medium is 1-inch-wide punched cards, magnetic tape,and even 35-mm motion picture film.There are two other methods of input to the NC system which should be mentioned. The first is by manual entry of instructional data to the controller unit .This is time-consuming and is rarely used except as an auxiliary means of control or when only one or a very limited number of parts are to be made. The second method of input is by means of a direct link with a computer .This is called direct numerical control, or DNC.The program of instructions is prepared by someone called a part programmer. Theprogramm er’s job is to provide a set of detailed instructions by which the sequence of processing steps is to be performed. For a machining operation, the processing steps involve the relative movement of the machine tool table and the cutting tool.Controller unitThe second basic component of the NC system is the controller unit . This consists of the electronics and hardware that read and interpret the program of instructions and convert it into mechanical actions of the machine tool . The typical elements of the controller unit include the tape reader , a data buffer, signal output channels to the machine tool, feedback channels from the machine tool, and the sequence controls to coordinate the overall operation of the foregoing elements.The type reader is an electrical-mechanical device for winding and reading the punched tape containing the program of instructions . The data contained on the tape are read into the data buffer , The purpose of this device is to store the input instructions in logical blocks of information. A block of information usually represents one complete step in the sequence of processing elements. For example, one block may be the data required to move the machine table to a certain position and drill a hole at that location .The signal output channels are connected to the servomotors and other controls in the machine tool. Through these channels, the instructions are sent to themachine tool from the controller unit. To make certain that the instruction have been properly executed by the machine, feedback data are sent back to the controller via the feedback channels. The most important function of this return loop is to assure that table and workpart have been properly located with respect to the tool. Most NC machine tools in use today are provided with position feedback controls for this purpose and are referred to ae closed-loop systems. However, in recent years there has been a growth in the use of open-loop systems, which do not make use of feedback signals to the controller unit. The advocates of the open-loop concept claim that the reliability of the system is great enough that feedback controls are not needed and are an unnecessary extra cost.Sequence controls coordinate the activities of the other elements of the controller unit. The tape reader is actuated to read data into the buffer from the tape, signals are sent to，and so on. These types of operations must be synchronized and this is the function of the sequence controls.Another element of the NC system, which may be physically part of the controller unit or part of the machine tool, is the control panel. The control panel or control consolecontains the dials and switches by which the machine operator runs the NC system. It may also contain data displays to provide information to the operator. Although the NC system is an automatic system, the human operator is still needed to turn the machine on and off, to change tools (some NC systems have automatic tool changers), to load and unload the machine, and to perform various other duties. To be able to discharge these duties, the operator must be able to control the system, and this is done through the control panel.The third basic component of an NC system is the machine tool or other controlled process. It is the part of the NC system which performs useful work. In the most common example of an NC system, one designed to perform machining operations, the machine tool consists of the worktable and spindle as well as the motors and controls necessary to drive them. It also includes the cutting tools, work fixtures, and other auxiliary equipment needed in the machining operation. Programmable Logic ControllersA programmable logic controller (PLC) is a solid-state device used to control machine motion or process operation by means of a stored program. The PLC sends output control signals and receives input signals through input/output (I/O) devices.A PLC controls outputs in response to stimuli at the inputs according to the logic prescribed by the stored program The inputs are made up of limit switches, ,pushbuttons, thumbwheels, switches, pulses, analog signals, ASCII serial data, and binary or BCD data from absolute position encoders. The outputs are voltage or current levels to drive end devices such as solenoids, motor starters, relays, lights, and so on. Other output devices include analog devices, digital BCD displays, ASCII compatible devices servo variable-speed drives, and even computers.Programmable controllers were developed (circa in 1968) when General Motors Corp, and other automobile manufacturers were experimenting to see if there might be an alternative to scrapping all their hardwired control panels of machine tools and other production equipment during a model changeover. This annual tradition was necessary because rewiring of the panels was more expensive than buying new ones. The automotive companies approached a number of control equipment manufacturers and asked them to develop a control system that would have a longer productive life without major rewiring, but would still be understandable to and repairable by plant personnel. The new product was named a "programmable controller".The processor part of the PLC contains a central processing unit and memory. The central processing unit (CPU) is the "traffic director" of the processor, the memory stores information. Coming into the processor are the electrical signals from the input devices, as conditioned by the input module to voltage levels acceptable to processor logic. The processor scans the state of I / O and updates outputs based on instructions stored in the memory of the PLC. For example, the processor may be programmed so that if an input connected to a limit switch is true (limit switch closed), then a corresponding output wired to an output module is to be energized. This output might be a solenoid, for example. The processor remembers this command through its memory and compares on each scan to see if that limit switch is, in fact, closed. If it is closed, the processor energizes the solenoid by turning on the output module.The output device, such as a solenoid or motor starter, is wired to an output module's terminal, and it receives its shift signal from the processor, in effect, the processor is performing a long and complicated series of logic decisions. The PLC performs such decisions sequentially and in accordance with the stored program. Similarly, analog I / O allows the processor to make decisions based on themagnitude of a signal, rather than just if it is on or off. For example, the processor may be programmed to increase or decrease the steam flow to a boiler (analog output) based on a comparison of the actual temperature in the boiler {analog input) to the desired temperature. This is often performed by utilizing the built-in PID (proportional, integral, derivative) capabilities of the processor.Because a PLC is "software based", its control logic functions can be changed by reprogramming its memory. Keyboard programming devices facilitate entry of the revised program, which can be designed to cause an existing machine or process to operate in a different sequence or to respond to different levels of, or combinations of stimuli. Hardware modifications are needed only if additional, changed, or relocated input/output devices are involved.Transfer MachinesThe highest degree of automation obtainable with special-purpose, multifunction machines is achieved by using transfer machines. Transfer machines are essentially acombination of individual workstations arranged in the required sequence, connected by work transfer devices, and integrated with interlocked controls. Workpieces are automatically transferred between the. stations, which are equipped with horizontal vertical, or angular units to perform machining, gaging, workpiece repositioning, assembling, washing, or other operations. The two major classes of transfer machines are rotary and in-line types.An important advantage of transfer machines is that they permit the maximum number of operations to be performed simultaneously There is relatively no limitation on the number of workpiece surfaces or planes that can be machined, since devices can be interposed in transfer machines at practically any point for inverting, rotating, or orienting the workpiece, so as to complete the machining operations. Work repositioning also minimizes the need for angular machining heads and allows operations to be performed in optimum time. Complete processing, from rough, casting or forgings to finished parts is often possible.One or more finished parts are produced on a transfer machine with each index of thetransfer system that moves the parts from station to station. Production efficiencies of such machines generally range from 50% for a machine producing a variety of different parts to 85% for a machine producing one part, in. highproduction, depending upon the workpiece and how the machine is operated (materials handling method, maintenance procedures, etc. )All types of machining operations, such as drilling, tapping, reaming, boring, and milling, are economically combined on transfer machines. Lathe-type operations such as turning and facing are also being performed on in-line transfer machine, with the workpieces being rotated in selected machining stations. Turning operations are performed in lathe-type segments in which multiple toolholders are fed on slides mounted on tunnel-type bridge units. Workpieces are located on centers and rotated by chucks at each turning station. Turning stations with CNC are available for use on in-line transfer machines. The CNC units allow the machine cycles to be easily altered to accommodate changes in workpiece design and can also be used for automatic tool adjustments.Maximum production economy on transfer lines is often achieved by assembling partsto the workpieces during their movement through the machine. Such items as bushings, seals, welch plugs, and heat tubes can be assembled and then machined or tested during the transfer machining sequence. Automatic nut torquing following the application of part subassemblies can also be carried out.Gundrillinq or reaming on transfer machines is an ideal applicat!on provided that proper machining units are employed and good bushing practices are followed. Contour boring and turning of spherical seats and other surfaces can be done with tracer-controlled single-point inserts, thus eliminating the need for costly special form tools. In-process gaging of reamed or bored holes and automatic tool setting are done on transfer machines to maintain close tolerances.Less conventional operations sometimes performed on transfer machines include grinding, induction heating of ring gears for shrink-fit pressing on flywheels, induction hardening of valve seats, deep rolling to apply compressive preloads, and burnishinq.Transfer machines have long been used in the automotive industry for producing identical components at high production rates with a minimum of manual part handling. In addition to decreasing labor requirements, such machines ensure consistently uniform, high-quality parts at lower cost. They are no longer confined just to rough machining and now often eliminate the need for subsequent operations such as grinding and honing.More recently, there has been an increasing demand for transfer machines to handle lower volumes of similar or even different parts in smaller sizes, with means for quick changeover between production runs. Built-in flexibility, the ability to rearrange andinterchange machining units, and the provision of idle stations increases the cost of any transfer machine, but such features are economically feasible when product redesigns are common. Many such machines are now being used in nonautomotive applications for lower production requirements.Special features now available to reduce the time required for part changeover include standardized dimensions, modular construction, interchangeable fixtures mounted on master pallets that remain on the machine, interchangeable fixture components, the ability to lock out certain stations for different parts by means of selector switches, and programmable controllers. Product design is also important, and common transfer and clamping surfaces should be provided on different parts whenever possible.中文翻译计算机与制造业计算机辅助设计计算机正在将制造业带入信息时代。
机械工程毕业设计外文翻译
毕业设计论文外文资料原文及译文学院：机电工程学院专业：机械设计制造及其自动化班级：学号：姓名：Mechanical engineering1.The porfile of mechanical engineeringEngingeering is a branch of mechanical engineerig,it studies mechanical and power generation especially power and movement.2.The history of mechanical engineering18th century later periods,the steam engine invention has provided a main power fountainhead for the industrial revolution,enormously impelled each kind of mechznical biting.Thus,an important branch of a new Engineering – separated from the civil engineering tools and machines on the branch-developed together with Birmingham and the establishment of the Associantion of Mechanical Engineers in 1847 had been officially recognized.The mechanical engineering already mainly used in by trial and error method mechanic application technological development into professional engineer the scientific method of which in the research,the design and the realm of production used .From the most broad perspective,the demend continuously to enhance the efficiencey of mechanical engineers improve the quality ofwork,and asked him to accept the history of the high degree of education and training.Machine operation to stress not only economic but also infrastructure costs to an absolute minimun.3.The field of mechanical engineeringThe commodity machinery development in the develop country,in the high level material life very great degree is decided each kind of which can realize in the mechanical engineering.Mechanical engineers unceasingly will invent the machine next life to produce the commodity,unceasingly will develop the accuracy and the complexity more and more high machine tools produces the machine.The main clues of the mechanical development is:In order to enhance the excellent in quality and reasonable in price produce to increase the precision as well as to reduce the production cost.This three requirements promoted the complex control system development.The most successful machine manufacture is its machine and the control system close fusion,whether such control system is essentially mechanical or electronic.The modernized car engin production transmission line(conveyer belt)is a series of complex productions craft mechanizationvery good example.The people are in the process of development in order to enable further automation of the production machinery ,the use of a computer to store and handle large volumes of data,the data is a multifunctional machine tools necessary for the production of spare parts.One of the objectives is to fully automated production workshop,three rotation,but only one officer per day to operate.The development of production for mechanical machinery must have adequate power supply.Steam engine first provided the heat to generate power using practical methods in the old human,wind and hydropower,an increase of engin .New mechanical engineering industry is one of the challenges faced by the initial increase thermal effciency and power,which is as big steam turbine and the development of joint steam boilers basically achieved.20th century,turbine generators to provide impetus has been sustained and rapid growth,while thermal efficiency is steady growth,and large power plants per kW capital consumption is also declining.Finally,mechanical engineers have nuclear energy.This requires the application of nuclear energy particularly high reliability and security,which requires solving many new rge power plants and the nuclear power plant control systems have become highly complex electroonics,fluid,electricity,water and mechanical parts networks All in all areas related to the mechanical engineers.Small internal combustion engine,both to the type (petrol and diesel machines)or rotary-type(gas turbines and Mong Kerr machine),as well as their broad application in the field of transport should also due to mechanical enginerrs.Throughout the transport,both in the air and space,or in the terrestrial and marine,mechanial engineers created a variety of equipment and power devices to their increasing cooperation with electrical engineers,especially in the development of appropration control systems.Mechanical engineers in the development of military weapons technology and civil war ,needs a similar,though its purpose is to enhance rather than destroy their productivity.However.War needs a lot of resources to make the area of techonlogy,many have a far-reaching development in peacetime efficiency.Jet aircraft and nuclear reactors are well known examples.The Biological engineering,mechanical engineering biotechnology is a relatively new and different areas,it provides for the replacement of the machine or increase thebody functions as well as for medical equipment.Artficial limbs have been developed and have such a strong movement and touch response function of the human body.In the development of artificial organ transplant is rapid,complex cardiac machines and similar equipment to enable increasingly complex surgery,and injuries and ill patients life functions can be sustained.Some enviromental control mechanical engineers through the initial efforts to drainage or irrigation pumping to the land and to mine and ventilation to control the human environment.Modern refrigeration and air-conditioning plant commonaly used reverse heat engine,where the heat from the engine from cold places to more external heat.Many mechanical engineering products,as well as other leading technology development city have side effects on the environment,producing noise,water and air pollution caused,destroyed land and landscape.Improve productivity and diver too fast in the commodity,that the renewable naturalforces keep pace.For mechanical engineers and others,environmental control is rapidly developing area,which includes a possible development and production of small quantities of pollutants machine sequnce,and the development of new equipment and teachnology has been to reduce and eliminate pollution.4.The role of mechanical engineeringThere are four generic mechanical engineers in common to the above all domains function.The 1st function is the understanding and the research mechanical science foundation.It includes the power and movement of the relationship dynamics For example,in the vibration and movement of the relationship;Automatic control;Study of the various forms of heart,energy,power relations between the thermodynamic;Fluidflows; Heat transfer; Lubricant;And material properties.The 2nd function will be conducts the research,the desing and the development,this function in turn attempts to carry on the essential change to satisfy current and the future needs.This not only calls for a clear understanding of mechanical science,and have to breakdown into basic elements of a complex system capacity.But also the need for synthetic and innovative inventions.The 3rd function is produces the product and the power,include plan,operation and maintenance.Its goal lies in the maintenance eitherenhances the enterprise or the organization longer-tern and survivabilaty prestige at the same time,produces the greatest value by the least investments and the consumption.The 4th function is mechanical engineer’s coordinated function,including the management,the consultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use the science for a long time the method,but is not traditional or the intuition method tendency,this is a mechanical engineering skill aspect which unceasingly grows.These new rationalization means typical names include:The operations research,the engineering economics,the logical law problem analysis(is called PABLA) However,creativity is not rationalization.As in other areas,in mechanical engineering,to take unexpected and important way to bring about a new capacity,still has a personal,marked characteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,such as:the instrument and the measuring appliance in very many situations,the machine design must use the knowledge of discipline the and so on mathematics,materials science and mechanics.Mechanical engineering desgin includeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnical engineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Design stages.The entire desgin process from start to finish,in the process,a demand that is designed for it and decided to do the start.After a lot of repetition,the final meet this demand by the end of the design procees and the plan.Design considerations.Sometimes in a system is to decide which parts needs intensity parts of geometric shapesand size an important factor in this context that we must consider that the intensity is an important factor in the design.When we use expression design considerations,we design parts that may affect the entire system design features.In the circumstances specified in the design,usually for a series of such functions must be taken into account.Howeever,to correct purposes,we should recognize that,in many cases thedesign of important design considerations are not calculated or test can determine the components or systems.Especially students,wheen in need to make important decisions in the design and conduct of any operation that can not be the case,they are often confused.These are not special,they occur every day,imagine,for example,a medical laboratory in the mechanical design,from marketing perspective,people have high expectations from the strength and relevance of impression.Thick,and heavy parts installed together:to produce a solid impression machines.And sometimes machinery and spare parts from the design style is the point and not the other point of view.Our purpose is to make those you do not be misled to believe that every design decision will needreasonable mathematical methods.Manufacturing refers to the raw meterials into finished products in the enterprise.Create three distinct phases.They are:input,processing exprot.The first phase includes the production of all products in line with market needs essential.First there must be the demand for the product,the necessary materials,while also needs such as energy,time,human knowledge and technology resourcess .Finall,the need for funds to obtain all the other resources. Lose one stage after the second phase of the resources of the processes to be distributed.Processing of raw materials into finished products of these processes.To complete the design,based on the design,and then develop plans.Plan implemented through various production processes.Management of resources and processes to ensure efficiency and productivity.For example,we must carefully manage resources to ensure proper use of funds.Finally,people are talking about the product market was cast.Stage is the final stage of exporting finished or stage.Once finished just purchased,it must be delivered to the users.According to product performance,installation and may have to conduct further debugging in addition,some products,especially those very complex products User training is necessary.6.The processes of materials and maunfacturingHere said engineering materials into two main categories:metals and non-ferrous,high-performance alloys and power metals.Non-metallic futher divided into plastice,synthetic rubber,composite materials and ceramics.It said the productionproccess is divided into several major process,includingshape,forging,casting/ founding,heat treatment,fixed/connections ,measurement/ quality control and materal cutting.These processes can be further divide into each other’s craft.Various stages of the development of the manufacturing industry Over the years,the manufacturing process has four distinct stages of development, despite the overlap.These stages are:The first phase is artisanal,the second Phase is mechanization.The third phase is automation the forth Phase is integrated.When mankind initial processing of raw materials into finished products will be,they use manual processes.Each with their hands and what are the tools manuslly produced.This is totally integrated production take shape.A person needs indentification,collection materials,the design of a product to meet that demand,the production of such products and use it.From beginning to end,everything is focused on doing the work of the human ter in the industrial revolution introduced mechanized production process,people began to use machines to complete the work accomplished previously manual. This led to the specialization.Specialization in turn reduce the manufacture of integrated factors.In this stage of development,manufacturing workers can see their production as a whole represent a specific piece of the part of the production process.One can not say that their work is how to cope with the entire production process,or how they were loaded onto a production of parts finished.Development of manufacting processes is the next phase of the selection process automation.This is a computer-controlled machinery and processes.At this stage,automation island began to emerge in the workshop lane.Each island represents a clear production process or a group of processes.Although these automated isolated island within the island did raise the productivity of indivdual processes,but the overall productivity are often not change.This is because the island is not caught in other automated production process middle,but not synchronous with them .The ultimate result is the efficient working fast parked through automated processes,but is part of the stagnation in wages down,causing bottlenecks.To better understand this problem,you can imagine the traffic in the peak driving a red light from the red Service Department to the next scene. Occasionally you will find a lot less cars,more than being slow-moving vehicles,but the results can be found by thenext red light Brance.In short you real effect was to accelerate the speed of a red Department obstruction offset.If you and other drivers can change your speed and red light simultaneously.Will advance faster.Then,all cars will be consistent,sommth operation,the final everyone forward faster.In the workshop where the demand for stable synchronization of streamlined production,and promoted integration of manufacturing development.This is a still evolving technology.Fully integrated in the circumstances,is a computer-controllrd machinery and processing.integrated is completed through computer.For example in the preceding paragraph simulation problems,the computer will allow all road vehicles compatible with the change in red.So that everyone can steady traffic.Scientific analysis of movement,timing and mechanics of the disciplines is that it is composed of two pater:statics and dynamics.Statics analyzed static system that is in the system,the time is not taken into account,research and analysis over time and dynamics of the system change.Dynameics from the two componets.Euler in 1775 will be the first time two different branches: Rigid body movement studies can conveniently divided into two parts:geometric and mechanics.The first part is without taking into account the reasons for the downward movement study rigid body from a designated location to another point of the movement,and must use the formula to reflect the actual,the formula would determine the rigid body every point position. Therefore,this study only on the geometry and,more specifically,on the entities from excision.Obviously,the first part of the school and was part of a mechanical separation from the principles of dynamics to study movement,which is more than the two parts together into a lot easier.Dynamics of the two parts are subsequently divided into two separate disciplines,kinematic and dynamics,a study of movement and the movement strength.Therefore,the primary issue is the design of mechanical systems understand its kinematic.Kinematic studies movement,rather than a study of its impact.In a more precise kinematic studies position,displacement,rotation, speed,velocity and acceleration of disciplines,for esample,or planets orbiting research campaing is a paradigm.In the above quotation content should be pay attention that the content of the Euler dynamics into kinematic and rigid body dynamics is based on the assumptionthat they are based on research.In this very important basis to allow for the treatment of two separate disciplines.For soft body,soft body shape and even their own soft objects in the campaign depends on the role of power in their possession.In such cases,should also study the power and movement,and therefore to a large extent the analysis of the increased complexity.Fortunately, despite the real machine parts may be involved are more or less the design of machines,usually with heavy material designed to bend down to the lowest parts.Therefore,when the kinematic analysis of the performance of machines,it is often assumed that bend is negligible,spare parts are hard,but when the load is known,in the end analysis engine,re-engineering parts to confirm this assnmption.机械工程1.机械工程简介机械工程是工程学的一个分支，它研究机械和动力的产，尤其是力和动力。
(完整版)机械类外文文献翻译
文献翻译英文原文：NOVEL METHOD OF REALIZING THE OPTIMAL TRANSMISSION OF THE CRANK-AND-ROCKER MECHANISM DESIGN Abstract: A novel method of realizing the optimal transmission of the crank-and-rocker mechanism is presented. The optimal combination design is made by finding the related optimal transmission parameters. The diagram of the optimal transmission is drawn. In the diagram, the relation among minimum transmission angle, the coefficient of travel speed variation, the oscillating angle of the rocker and the length of the bars is shown, concisely, conveniently and directly. The method possesses the main characteristic. That it is to achieve the optimal transmission parameters under the transmission angle by directly choosing in the diagram, according to the given requirements. The characteristics of the mechanical transmission can be improved to gain the optimal transmission effect by the method. Especially, the method is simple and convenient in practical use.Keywords：Crank-and-rocker mechanism, Optimal transmission angle, Coefficient of travel speed variationINTRODUCTIONBy conventional method of the crank-and-rocker design, it is very difficult to realize the optimal combination between the various parameters for optimal transmission. The figure-table design method introduced in this paper can help achieve this goal. With given conditions, we can, by only consulting the designing figures and tables, get the relations between every parameter and another of the designed crank-and-rocker mechanism. Thus the optimal transmission can be realized.The concerned designing theory and method, as well as the real cases of its application will be introduced later respectively.1ESTABLISHMENT OF DIAGRAM FOR OPTIMAL TRANSMISSION DESIGNIt is always one of the most important indexes that designers pursue to improve the efficiency and property of the transmission. The crank-and-rocker mechanism is widely used in the mechanical transmission. How to improve work ability and reduce unnecessary power losses is directly related to the coefficient of travel speed variation, the oscillating angle of the rocker and the ratio of the crank and rocker. The reasonable combination of these parameters takes an important effect on the efficiency and property of the mechanism, which mainly indicates in the evaluation of the minimum transmission angle.The aim realizing the optimal transmission of the mechanism is how to find themaximum of the minimum transmission angle. The design parameters are reasonably combined by the method of lessening constraints gradually and optimizing separately. Consequently, the complete constraint field realizing the optimal transmission is established.The following steps are taken in the usual design method. Firstly, the initial values of the length of rocker 3l and the oscillating angle of rocker ϕ are given. Then the value of the coefficient of travel speed variation K is chosen in the permitted range. Meanwhile, the coordinate of the fixed hinge of crank A possibly realized is calculated corresponding to value K .1.1 Length of bars of crank and rocker mechanismAs shown in Fig.1, left arc G C 2 is the permitted field of point A . Thecoordinates of point A are chosen by small step from point 2C to point G .The coordinates of point A are 02h y y c A -= (1)22A A y R x -= (2)where 0h , the step, is increased by small increment within range(0,H ). If the smaller the chosen step is, the higher the computational precision will be. R is the radius of the design circle. d is the distance from 2C to G .2cos )2cos(22cos 33ϕθϕϕ⎥⎦⎤⎢⎣⎡--+=l R l d (3) Calculating the length of arc 1AC and 2AC , the length of the bars of themechanism corresponding to point A is obtained [1,2].1.2 Minimum transmission angle min γMinimum transmission angle min γ(see Fig.2) is determined by the equations [3]322142322min 2)(cos l l l l l l --+=γ (4) 322142322max 2)(cos l l l l l l +-+=γ (5) max min180γγ-︒=' (6) where 1l ——Length of crank(mm)2l ——Length of connecting bar(mm)3l ——Length of rocker(mm)4l ——Length of machine frame(mm)Firstly, we choose minimum comparing min γ with minγ'. And then we record all values of min γ greater than or equal to ︒40 and choose the maximum of them.Secondly, we find the maximum of min γ corresponding to any oscillating angle ϕ which is chosen by small step in the permitted range (maximum of min γ is different oscillating angle ϕ and the coefficient of travel speed variation K ).Finally, we change the length of rockerl by small step similarly. Thus we3γcorresponding to the different length of bars, may obtain the maximum ofmindifferent oscillating angle ϕand the coefficient of travel speed variation K.Fig.3 is accomplished from Table for the purpose of diagram design.It is worth pointing out that whatever the length of rocker 3l is evaluated, the location that the maximum of min γ arises is only related to the ratio of the length of rocker and the length of machine frame 3l /4l , while independent of 3l .2 DESIGN METHOD2.1 Realizing the optimal transmission design given the coefficient of travelspeed variation and the maximum oscillating angle of the rockerThe design procedure is as follows.(1) According to given K and ϕ, taken account to the formula the extreme included angle θ is found. The corresponding ratio of the length of bars 3l /4l is obtained consulting Fig.3.︒⨯+-=18011K K θ (7) (2) Choose the length of rocker 3l according to the work requirement, the length of the machine frame is obtained from the ratio 3l /4l .(3) Choose the centre of fixed hinge D as the vertex arbitrarily, and plot an isosceles triangle, the side of which is equal to the length of rocker 3l (see Fig.4), andϕ=∠21DC C . Then plot 212C C M C ⊥, draw N C 1, and make angleθ-︒=∠9012N C C . Thus the point of intersection of M C 2 and N C 1 is gained. Finally, draw the circumcircle of triangle 21C PC ∆.(4) Plot an arc with point D as the centre of the circle, 4l as the radius. The arc intersections arc G C 2 at point A . Point A is just the centre of the fixed hinge of the crank.Therefore, from the length of the crank2/)(211AC AC l -= (8)and the length of the connecting bar112l AC l -= (9)we will obtain the crank and rocker mechanism consisted of 1l , 2l , 3l , and 4l .Thus the optimal transmission property is realized under given conditions.2.2 Realizing the optimal transmission design given the length of the rocker (or the length of the machine frame) and the coefficient of travel speed variationWe take the following steps.(1) The appropriate ratio of the bars 3l /4l can be chosen according to given K . Furthermore, we find the length of machine frame 4l (the length of rocker 3l ).(2) The corresponding oscillating angle of the rocker can be obtained consulting Fig.3. And we calculate the extreme included angle θ.Then repeat (3) and (4) in section 2.13 DESIGN EXAMPLEThe known conditions are that the coefficient of travel speed variation1818.1=K and maximum oscillating angle ︒=40ϕ. The crankandrockermechanism realizing the optimal transmission is designed by the diagram solution method presented above.First, with Eq.(7), we can calculate the extreme included angle ︒=15θ. Then, we find 93.0/43=l l consulting Fig.3 according to the values of θ and ϕ.If evaluate 503=l mm, then we will obtain 76.5393.0/504==l mm. Next, draw sketch(omitted).As result, the length of bars is 161=l mm,462=l mm,503=l mm,76.534=l mm.The minimum transmission angle is︒=--+=3698.462)(arccos 322142322min l l l l l l γ The results obtained by computer are 2227.161=l mm, 5093.442=l mm, 0000.503=l mm, 8986.534=l mm.Provided that the figure design is carried under the condition of the Auto CAD circumstances, very precise design results can be achieved.4 CONCLUSIONSA novel approach of diagram solution can realize the optimal transmission of the crank-and-rocker mechanism. The method is simple and convenient in the practical use. In conventional design of mechanism, taking 0.1 mm as the value of effective the precision of the component sizes will be enough.译文：认识曲柄摇臂机构设计的最优传动方法摘要：一种曲柄摇臂机构设计的最优传动的方法被提出。
机械设计外文翻译(中英文)
Machine design theoryThe machine design is through designs the new product or improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question.Carries on each kind of machine design work to be usually called designs the personnel or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge.If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of productMust regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spendsthe time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea.Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the question are solved, can manifest new goods come into the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itself does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method.In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel''s basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process.Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. In order to carry on the effective exchange, needs to solve the following problem:(1) designs whether this product truly does need for the people? Whether there is competitive ability(2) does this product compare with other companies'' existing similar products?(3) produces this kind of product is whether economical?(4) product service is whether convenient?(5) product whether there is sale? Whether may gain?Only has the time to be able to produce the correct answer to above question. But, the product design, the manufacture and the sale only can in carry on to the above question preliminary affirmation answer foundation in. Project engineer also should through the detail drawing and the assembly drawing, carries on the consultation together with the branch of manufacture to the finally design proposal.Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the components the production to change easily. But, in the project change must have to pass through designs the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembly or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instances exactly showed the design is a dynamic process. Always has a better method to complete the design work, designs the personnel to be supposed unceasingly diligently, seeks these better method.Recent year, the engineerig material choice already appeared importantly. In addition, the choice process should be to the material continuously the unceasing again appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The environmental pollution, material recycling aspect and so on use, worker''s health and security frequently can attach the new limiting condition to the choice of material. In order to reduce the weight or saves the energy, possibly can request the use different material. Comes from domestic and international competition, to product service maintenance convenience request enhancement and customer''s aspect the and so on feedback pressure, can urge the people to carry on to the material reappraises. Because the material does not select when created the product responsibility lawsuit, has already had the profoundinfluence. In addition, the material and between the material processing interdependence is already known by the people clearly. Therefore, in order to can and guarantees the quality in the reasonable cost under the premise to obtain satisfaction the result, project engineer makes engineers all to have earnestly carefully to choose, the determination and the use material.Makes any product the first step of work all is designs. Designs usually may divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is whether feasible; If is feasible, then should makes the further improvement to or several plans. In this stage, the question which only must consider about the choice of material is: Whether has the performance to conform to the request material to be possible to supply the choice; If no, whether has a bigger assurance all permits in the cost and the time in the limit develops one kind of new material.In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite complete blueprint in this stage, chooses and determines each kind of components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the product to the production base in front of, should replace certain materials, but, absolutely cannot this point take not earnestly chooses the material the excuse. Should unify the product the function, earnestly carefully considers the product the outward appearance, the cost and the reliability. Has the achievement very much the company when manufacture all prototypes, selects the material should the material which uses with its production in be same, and uses the similar manufacture technology as far as possible. Like this has the advantage very much to the company. The function complete prototype if cannot act according to the anticipated sales volume economically to make, or is prototypical and the official production installment has in the quality and the reliable aspect is very greatly different, then this kind of prototypedoes not have the great value. Project engineer is best can completely complete the material in this stage the analysis, the choice and the determination work, but is not remains it to the production design stage does. Because, is carries on in the production design stage material replacement by other people, these people are inferior to project engineer to the product all functions understanding. In the production design stage, is should completely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the material quantity can quite be easy to guarantee the supply.In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certain cheap materials to take the substitute. However, in the majority situation, in will carry on the production later to change the material to have in to start before the production to change the price which the material will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situations. Started after the production manufacture to appear has been possible to supply the use the new material is replaces the material the most common reason. Certainly, these new materials possibly reduce the cost, the improvement product performance. But, must carry on the earnest appraisal to the new material, guarantees its all performance all to answer the purpose. Must remember that, the new material performance and the reliable very few pictures materials on hand such understood for the people. The majority of products expiration and the product accident caused by negligence case is because in selects the new material to take in front of substitution material, not truly understood their long-term operational performance causes.The product responsibility lawsuit forces designs the personnel and the company when the choice material, uses the best procedure. In the material process, five most common questions are: (a) did not understand or cannot use about the material application aspect most newly the best information paper; (b) has not been able to foresee and to consider the dusk year possible reasonable use (for example to have the possibility, designs the personnel also to be supposed further to forecast and the consideration because product application method not when creates consequence.ecent years many products responsibilities lawsuit case, because wrongly uses theplaintiff which the product receives the injury to accuse produces the factory, and wins the decision); (c) uses the material data not entire perhaps some data are indefinite, works as its long-term performance data is the like this time in particular;(d) the quality control method is not suitable and not after the confirmation; (e) the personnel which completely is not competent for the post by some chooses the material.Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses the appearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of material according to the suitable procedure, may greatly reduce the lawsuit the quantity.May see from the above discussion, the choice material people should to the material nature, the characteristic and the processing method have comprehensive and thebasic understanding.翻译：机械设计理论机械设计，通过设计新产品或改进老产品，以满足人类需要的应用技术科学。
机械设计制造及其自动化毕业论文中英文资料外文翻译
机械设计创造及其自动化毕业论文外文文献翻译INTEGRATION OF MACHINERY译文题目专业机械设计创造及其自动化外文资料翻译INTEGRATION OF MACHINERY（From ELECTRICAL AND MACHINERY INDUSTRY）ABSTRACTMachinery was the modern science and technology development inevitable result, this article has summarized the integration of machinery technology basic outline and the development background .Summarized the domestic and foreign integration of machinery technology present situation, has analyzed the integration of machinery technology trend of development.Key word： integration of machinery ，technology， present situation ，product t，echnique of manufacture ，trend of development0. Introduction modern science and technology unceasing development, impelled different discipline intersecting enormously with the seepage, has caused the project domain technological revolution and the transformation .In mechanical engineering domain, because the microelectronic technology and the computer technology rapid development and forms to the mechanical industry seepage the integration of machinery, caused the mechanical industry the technical structure, the product organization, the function and the constitution, the production method and the management systemof by machinery for the characteristic integration ofdevelopment phase.1. Integration of machinery outline integration of machinery is refers in the organization new owner function, the power function, in the information processing function and the control function introduces the electronic technology, unifies the system the mechanism and the computerization design and the software which constitutes always to call. The integration of machinery development also has become one to have until now own system new discipline, not only develops along with the science and technology, but also entrusts with the new content .But its basic characteristic may summarize is: The integration of machinery is embarks from the system viewpoint, synthesis community technologies and so on utilization mechanical technology, microelectronic technology, automatic control technology, computer technology, information technology, sensing observation and control technology, electric power electronic technology, connection technology, information conversion technology as well as software programming technology, according to the system function goal and the optimized organization goal, reasonable disposition and the layout various functions unit, in multi-purpose, high grade, redundant reliable, in the low energy consumption significance realize the specific function value, and causes the overall system optimization the systems engineering technology .From this produces functional system, then becomes an integration of machinery systematic or the integration of machinery product. Therefore, of coveringtechnology is based on the above community technology organic fusion one kind of comprehensive technology, but is not mechanical technical, the microelectronic technology as well as other new technical simple combination, pieces together .This is the integration of machinery and the machinery adds the machinery electrification which the electricity forms in the concept basic difference .The mechanical engineering technology has the merely technical to develop the machinery electrification, still was the traditional machinery, its main function still was replaces with the enlargement physical strength .But after develops the integration of machinery, micro electron installment besides may substitute for certain mechanical parts the original function, but also can entrust with many new functions,like the automatic detection, the automatic reduction information, demonstrate the record, the automatic control and the control automatic diagnosis and the protection automatically and so on .Not only namely the integration of machinery product is human's hand and body extending, human's sense organ and the brains look, has the intellectualized characteristic is the integration of machinery and the machinery electrification distinguishes in the function essence.2. Integration of machinery development condition integration of machinery development may divide into 3 stages roughly.20th century 60's before for the first stage, this stage is called the initial stage .In this time, the people determination not on own initiative uses the electronic technology the preliminary achievement to consummate the mechanical product the performance .Specially in Second World War period, the war has stimulated the mechanical product and the electronic technology union, these mechanical and electrical union military technology, postwar transfers civilly, to postwar economical restoration positive function .Developed and the development at that time generally speaking also is at the spontaneouscondition .Because at that time the electronic technology development not yet achieved certain level, mechanical technical and electronic technology union also not impossible widespread and thorough development, already developed the product was also unable to promote massively. The 20th century 70~80 ages for the second stage, may be called the vigorous development stage .This time, the computer technology, the control technology, the communication development, has laid the technology base for the integration of machinery development . Large-scale, ultra large scale integrated circuit and microcomputer swift and violent development, has provided the full material base for the integration of machinery development .This time characteristic is :①A mechatronics word first generally is accepted in Japan, probably obtains the quite widespread acknowledgment to 1980s last stages in the worldwide scale ;②The integration of machinery technology and the product obtained the enormous development ;③The various countries start to the integration of machinery technology and the product give the very big attention and the support. 1990s later periods, started the integration of machinery technology the new stagewhich makes great strides forward to the intellectualized direction, the integration of machinery enters the thorough development time .At the same time, optics, the communication and so on entered the integration of machinery, processes the technology also zhan to appear tiny in the integration of machinery the foot, appeared the light integration of machinery and the micro integration of machinery and so on the new branch; On the other hand to the integration of machinery system modeling design, the analysis and the integrated method, the integration of machinery discipline system and the trend of development has all conducted the thorough research .At the same time, because the hugeprogress which domains and so on artificial intelligence technology, neural network technology and optical fiber technology obtain, opened the development vast world for the integration of machinery technology .These research, will urge the integration of machinery further to establish the integrity the foundation and forms the integrity gradually the scientific system. Our country is only then starts from the beginning of 1980s in this aspect to study with the application .The State Councilsummary had considered fully on international the influence which and possibly brought from this about the integration of machinery technology developmenttrend .Many universities, colleges and institutes, the development facility and some large and middle scale enterprises have done the massive work to this technical development and the application, does not yield certain result, but and so on the advanced countries compared with Japan still has the suitable disparity.3. Integration of machinery trend of development integrations of machinery are the collection machinery, the electron, optics, the control, the computer, the information and so on the multi-disciplinary overlapping syntheses, its development and the progress rely on and promote the correlation technology development and the progress .Therefore, the integration of machinery main development direction is as follows:3.1 Intellectualized intellectualizations are 21st century integration of machinery technological development important development directions .Theartificial intelligence obtains day by day in the integration of machinery constructor's research takes, the robot and the numerical control engine bedis to the machine behavior description, is in the control theory foundation, the absorption artificial intelligence, the operations research, the computer science, the fuzzy mathematics, the psychology, the physiology and the chaos dynamics and so on the new thought, the new method, simulate the human intelligence, enable it to have abilities and so on judgment inference, logical thinking, independent decision-making, obtains the higher control goal in order to .Indeed, enable the integration of machinery product to have with the human identical intelligence, is not impossible, also is nonessential .But, the high performance, the high speed microprocessor enable the integration of machinery product to have preliminary intelligent or human's partial intelligences, then is completely possible and essential.In the modern manufacture process, the information has become the control manufacture industry the determining factor, moreover is the most active actuation factor .Enhances the manufacture system information-handling capacity to become the modern manufacture science development a key point .As a result of the manufacture system information organization and structure multi-level, makes the information the gain, the integration and the fusion presents draws up the character, information measure multi-dimensional, as well as information organization's multi-level .In the manufacture information structural model, manufacture information uniform restraint, dissemination processing and magnanimous data aspects and so on manufacture knowledge library management, all also wait for further break through.Each kind of artificial intelligence tool and the computation intelligence method promoted the manufacture intelligence development in the manufacture widespread application .A kind based on the biological evolution algorithm computation intelligent agent, in includes thescheduling problem in the combination optimization solution area of technology, receives the more and more universal attention, hopefully completes the combination optimization question when the manufacture the solution speed and the solution precision aspect breaks through the question scale in pairs the restriction .The manufacture intelligence also displays in: The intelligent dispatch, the intelligent design, the intelligent processing, the robot study, the intelligent control, the intelligent craft plan, the intelligent diagnosis and so on are various These question key breakthrough, may form the product innovation the basic research system. Between 2 modern mechanical engineering front science different science overlapping fusion will have the new science accumulation, the economical development and society's progress has had the new request and the expectation to the science and technology, thus will form the front science .The front science also has solved and between the solution scientific question border area .The front science has the obvious time domain, the domain and the dynamic characteristic .The project front science distinguished in the general basic science important characteristic is it has covered the key science and technology question which the project actual appeared.Manufacture system is a complex large-scale system, for satisfies the manufacture system agility, the fast response and fast reorganization ability, must profit from the information science, the life sciences and the social sciences and so on the multi-disciplinary research results, the exploration manufacture system new architecture, the manufacture pattern and the manufacture system effective operational mechanism .Makes the system optimization the organizational structure and the good movement condition is makes the system modeling , the simulation and the optimized essential target .Not only the manufacture system new architecture to makes the enterprise the agility and may reorganize ability to the demand response ability to have the vital significance, moreover to made the enterprise first floor production equipment the flexibility and may dynamic reorganization ability set a higher request .The biological manufacture view more and more many is introduced the manufacture system, satisfies the manufacture system new request.The study organizes and circulates method and technique of complicated system from the biological phenomenon, is a valid exit which will solve many hard nut to cracks that manufacturing industry face from now on currently .Imitating to living what manufacturing point is mimicry living creature organ of from the organization, from match more, from growth with from evolution etc. function structure and circulate mode of a kind of manufacturing system and manufacturing process.The manufacturing drives in the mechanism under, continuously by one's own perfect raise on organizing structure and circulating mode and thus to adapt the process of[with] ability for the environment .For from descend but the last product proceed together a design and make a craft rules the auto of the distance born, produce system of dynamic state reorganization and product and manufacturing the system tend automatically excellent provided theories foundation and carry out acondition .Imitate to living a manufacturing to belong to manufacturing science and life science of"the far good luck is miscellaneous to hand over", it will produce to the manufacturing industry for 21 centuries huge of influence .机电一体化摘要机电一体化是现代科学技术发展的必然结果,本文简述了机电一体化技术的基本概要和发展背景。
机械专业外文翻译(中英文翻译)
机械专业外文翻译（中英文翻译）第1页Among the methods of material conveying employed，belt conveyorsplaya very important part in the reliable carrying of material over longdistances at competitive cost．Conveyor systems have become larger and morecomplex and drive systems have also been going through a process of evolutionand will continue to do so．Nowadays，bigger belts require more power and havebrought the need for larger individual drives as well as multiple drives suchas 3 drives of 750 kW for one belt(this is the case for the conveyor drivesin Chengzhuang Mine)．The ability to control drive acceleration torque iscritical to belt conveyors’ performance．An efficient drive system should beable to provide smooth，soft starts while maintaining belt tensions withinthe specified safe limits．For load sharing on multiple drives．torque andspeed control are also important considerations in the drive system’s design.Due to the advances in conveyor drive control technology，at present many morereliable．Cost-effective and performance-driven conveyor drive systems[1]covering a wide range of power are available for customers’ choices. Full-voltage starters．With a full-voltage starter design，the conveyor head shaft is direct-coupled to the motor through the gear drive．Direct full-voltage startersare adequate for relatively low-power, simple-profile conveyors．With direct fu11-voltage starters．no control is provided for various conveyor loadsand．depending on the ratio between fu11- and no-1oad power requirements，empty starting times can be three or four times faster than full load．The maintenance-free starting system is simple，low-cost and very reliable．However, they cannot control starting torque and maximum stall torque；therefore．they are第2页 limited to the low-power, simple-profile conveyor belt drives．Reduced-voltage starters．As conveyor power requirements increase，controlling the applied motor torque during the acceleration period becomes increasinglyimportant．Because motor torque 1s a function of voltage，motor voltage must be controlled．This can be achieved through reduced-voltage starters by employinga silicon controlled rectifier(SCR)．A common starting method with SCRreduced-voltage starters is to apply low voltage initially to takeup conveyorbelt slack．and then to apply a timed linear ramp up to full voltage and beltspeed．However, this starting method will not produce constant conveyor beltacceleration．When acceleration is complete．the SCRs, which control the applied voltage to the electric motor． are locked in full conduction, providing fu11-linevoltage to the motor．Motors with higher torque and pull—uptorque，can provide better starting torque when combined with the SCR starters, which are availablein sizes up to 750 KW．Wound rotor induction motors．Wound rotor induction motors are connecteddirectly to the drive system reducer and are a modifiedconfiguration of a standardAC induction motor．By inserting resistance in series with the motor’s rotor windings．the modified motor control system controlsmotor torque．For conveyor starting，resistance is placed in series with the rotor for low initial torque．As the conveyor accelerates，the resistance is reduced slowly to maintain a constantacceleration torque．On multiple-drive systems．an external slip resistor may beleft in series with the rotor windings to aid in load sharing．The motor systems have a relatively simple design．However, the control systems for these can behighly complex，because they are based on computer control of the resistanceswitching．Today，the majority of control systems are custom designed to meet aconveyor system’s particular specifications．Wound rotor motors are appropriatefor systems requiring more than 400 kW ．DC motor．DC motors．available from a fraction of thousands of kW ，are designed to deliver constant torque below base speed and constant kW above base speed tothe maximum allowable revolutions per minute(r/min)．with the majority of conveyordrives, a DC shunt wound motor is used．Wherein the motor’srotating armature is第3页 connected externally．The most common technology for controlling DC drives is aSCR device． which allows for continual variable-speed operation．The DC drive system is mechanically simple, but can include complex custom-designed electronicsto monitor and control the complete system．This system option is expensive incomparison to other soft-start systems．but it is a reliable, cost-effective drivein applications in which torque,1oad sharing and variable speed are primaryconsiderations．DC motors generally are used with higher-power conveyors，including complex profile conveyors with multiple-drive systems，booster tripper systems needing belt tension control and conveyors requiring a wide variable-speed range．Hydrokinetic couplings，commonly referred to as fluid couplings．are composed of three basic elements; the driven impeller, which acts as a centrifugal pump；the driving hydraulic turbine known as the runner and a casing that encloses thetwo power components．Hydraulic fluid is pumped from the driven impeller to thedriving runner, producing torque at the driven shaft．Because circulating hydraulicfluid produces the torque and speed，no mechanical connection is required betweenthe driving and driven shafts．The power produced by this coupling is based onthe circulated fluid’s amount and density and the torque in proportion to inputspeed．Because the pumping action within the fluid coupling depends on centrifugalforces．the output speed is less than the input speed．Referred to as slip．this normally is between l% and 3%．Basic hydrokinetic couplings are available inconfigurations from fractional to several thousand kW ．Fixed-fill fluid couplings．Fixed-fill fluid couplings are the most commonlyused soft-start devices for conveyors with simpler belt profiles and limitedconvex/concave sections．They are relativelysimple,1ow-cost,reliable,maintenance free devices that provide excellent softstarting results to the majority of belt conveyors in use today．Variable-fill drain couplings．Drainable-fluid couplings work on the sameprinciple as fixed-fill couplings．The coupling’s impellers are mounted on the ACmotor and the runners on the driven reducer high-speed shaft．Housing mounted to the drive base encloses the working circuit．The coupling’s rotating casing contains第4页 bleed-off orifices that continually allow fluid to exit the working circuit intoa separate hydraulic reservoir．Oil from the reservoir is pumped through a heatexchanger to a solenoid-operated hydraulic valve that controls the filling of thefluid coupling．To control the starting torque of a single-drive conveyor system，the AC motor current must be monitored to provide feedback to the solenoid controlvalve．Variable fill drain couplings are used in medium to high-kW conveyor systemsand are available in sizes up to thousands of kW ．The drives can be mechanicallycomplex and depending on the control parameters．the system can be electronicallyintricate．The drive system cost is medium to high, depending upon size specified．Hydrokinetic scoop control drive．The scoop control fluid coupling consistsof the three standard fluid coupling components：a driven impeller, a driving runnerand a casing that encloses the working circuit．The casing is fitted with fixedorifices that bleed a predetermined amount of fluid into a reservoir．When the scoop tube is fully extended into the reservoir, the coupling is l00 percentfilled．The scoop tube, extending outside the fluid coupling，is positioned using an electric actuator to engage the tube from the fully retracted to the fullyengaged position．This control provides reasonably smooth acceleration rates．to but the computer-based control system is very complex．Scoop control couplings are applied on conveyors requiring single or multiple drives from l50 kW to 750kW.Variable frequency control is also one of the direct drive methods．The emphasizing discussion about it here is because that it has so uniquecharacteristic and so good performance compared with other driving methods forbelt conveyor． VFC devices Provide variable frequency and voltageto the inductionmotor, resulting in an excellent starting torque and acceleration rate for beltconveyor drives．VFC drives．available from fractional to several thousand(kW ),are electronic controllers that rectify AC line power to DC and，through an inverter, convert DC back to AC with frequency and voltage contro1．VFC drives adopt vector control or direct torquecontrol(DTC)technology，and can adopt different operating speeds according to different loads．VFC drives can make starting or stalling第5页 according to any given S-curves．realizing the automatic track for starting orstalling curves．VFC drives provide excellent speed and torque control for startingconveyor belts．and can also be designed to provide load sharing for multipledrives．easily VFC controllers are frequently installed on lower-powered conveyordrives，but when used at the range of medium-high voltage in the past．the structure of VFC controllers becomes very complicated due to the limitation of voltage ratingof power semiconductor devices，the combination of medium-high voltage drives andvariable speed is often solved with low-voltage inverters usingstep-uptransformer at the output，or with multiple low-voltage inverters connected inseries．Three-level voltage-fed PWM converter systems are recently showingincreasing popularity for multi-megawatt industrial driveapplications becauseof easy voltage sharing between the series devices and improved harmonic qualityat the output compared to two-level converter systems With simple series connectionof devices．This kind of VFC system with three 750 kW /2．3kV inverters has been successfully installed in ChengZhuang Mine for one 2．7-km long belt conveyordriving system in following the principle of three-level inverterwill be discussedin detail．Three-level voltage-fed inverters have recently become more and more popularfor higher power drive applications because of their easy voltage sharingfeatures．1ower dv/dt per switching for each of the devices，and superior harmonic quality at the output．The availability of HV-IGBTs has led to the design of anew range of medium-high voltage inverter using three-level NPC topology．This kind of inverter can realize a whole range with a voltagerating from 2．3 kV to 4．1 6 kV Series connection of HV-IGBT modules is used in the 3．3 kV and 4．1[2,3]6 kV devices．The 2．3 kV inverters need only one HV-IGBT per switch.To meet the demands for medium voltage applications．a three-level neutral point clamped inverter realizes the power section．In comparison to a two-levelinverter．the NPC inverter offers the benefit that three voltage levels can besupplied to the output terminals，so for the same output current quality，only第6页1/4 of the switching frequency is necessary．Moreover the voltage ratings of theswitches in NPC inverter topology will be reduced to 1/2．and the additional transient voltage stress on the motor can also be reduced to 1/2 compared to thatof a two-level inverter．The switching states of a three-level inverter are summarized in Table 1．U．V and W denote each of the three phases respectively；P N and O are the dc bus points．The phase U，for example，is in stateP(positive bus voltage)when theswitches S and S are closed，whereas it is in state N (negative bus voltage) 1u2uwhen the switches S and S are closed．At neutral point clamping，the phase is 3u4uin O state when either Sor S conducts depending on positive or negative phase 2u 3ucurrent polarity，respectively．For neutral point voltage balancing，the average current injected at O should be zero．For standard applications．a l2-pulse diode rectifier feeds the divided DC-linkcapacitor．This topology introduces low harmonics on the line side．For even higher requirements a 24-pulse diode rectifier can be used as an input converter．For more advanced applications where regeneration capability is necessary, an activefront．end converter can replace the diode rectifier, using the same structureas the inverter．Motor Contro1．Motor control of induction machines is realized by using a rotorflux．oriented vector controller．Fig．2 shows the block diagram of indirect vector controlled drive thatincorporates both constant torque and high speed field-weakening regions wherethe PW M modulator was used．In this figure，the command flux is generated as function of speed．The feedback speed is added with the feed forward slip commandsignal . the resulting frequency signal is integrated and then the unit vectorsignals(cos and sin )are generated．The vector rotator generates the voltageand angle commands for the PW M as shown．PWM Modulator．The demanded voltage vector is generated using an elaborate第7页 PWM modulator．The modulator extends the concepts of space-vector modulation tothe three-level inverter．The operation can be explained by starting from aregularly sampled sine-triangle comparison from two-level inverter．Instead of using one set of reference waveforms and one triangle defining the switchingfrequency， the three-level modulator uses two sets of reference waveforms U and r1U and just one triangle．Thus, each switching transition is used in an optimal r2way so that several objectives are reached at the same time．Very low harmonics are generated．The switching frequency is low and thusswitching losses are minimized．As in a two-level inverter, a zero-sequencecomponent can be added to each set of reference waveform s in order to maximizethe fundamental voltage component．As an additional degree of freedom，the position of the reference waveform s within the triangle can be changed．This can be used for current balance in the two halves of the DC-1ink．After Successful installation of three 750 kW /2．3 kV three-level invertersfor one 2．7 km long belt conveyor driving system in Chengzhuang Mine．The performance of the whole VFC system was tested．Fig．3 is taken from the test，which shows the excellent characteristic of the belt conveyor driving system withVFC controller．Fig．3 includes four curves．The curve 1 shows the belt tension．From the curve it can be find that the fluctuation range of the belt tension is very smal1．Curve 2 and curve 3 indicate current and torque separately．Curve 4 shows the velocityof the controlled belt．The belt velocity have the“s”shape characteristic．A1l the results of the test show a very satisfied characteristic for belt drivingsystem．Advances in conveyor drive control technology in recent years have resultedin many more reliable．Cost-effective and performance-driven conveyor drive systemchoices for users．Among these choices，the Variable frequency control (VFC) methodshows promising use in the future for long distance belt conveyor drives due toits excellent performances．The NPC three-level inverter using high voltage IGBTs第8页 make the Variable frequency control in medium voltage applications become muchmore simple because the inverter itself can provide the medium voltage needed atthe motor terminals，thus eliminating the step-up transformer in most applicationsin the past．The testing results taken from the VFC control system with NPC three．1evel inverters used in a 2．7 km long belt conveyor drives in Chengzhuang Mine indicatesthat the performance of NPC three-level inverter using HV-IGBTs together with thecontrol strategy of rotor field-oriented vector control for induction motor driveis excellent for belt conveyor driving system．第9页在运送大量的物料时，带式输送机在长距离的运输中起到了非常重要的竞争作用。
机械专业毕业设计外文翻译--选择最佳工具,几何形状和切削条件
附录附录1：英文原文Selection of optimum tool geometry and cutting conditionsusing a surface roughness prediction model for end milling Abstract Influence of tool geometry on the quality of surface produced is well known and hence any attempt to assess the performance of end milling should include the tool geometry. In the present work, experimental studies have been conducted to see the effect of tool geometry (radial rake angle and nose radius) and cutting conditions (cutting speed and feed rate) on the machining performance during end milling of medium carbon steel. The first and second order mathematical models, in terms of machining parameters, were developed for surface roughness prediction using response surface methodology (RSM) on the basis of experimental results. The model selected for optimization has been validated with the Chi square test. The significance of these parameters on surface roughness has been established with analysis of variance. An attempt has also been made to optimize the surface roughness prediction model using genetic algorithms (GA). The GA program gives minimum values of surface roughness and their respective optimal conditions.1 IntroductionEnd milling is one of the most commonly used metal removal operations in industry because of its ability to remove material faster giving reasonably good surface quality. It is used in a variety of manufacturing industries including aerospace and automotive sectors, where quality is an important factor in the production of slots, pockets, precision moulds and dies. Greater attention is given to dimensional accuracy and surface roughness of products by the industry these days. Moreover, surface finish influences mechanical properties such as fatigue behaviour, wear, corrosion, lubrication and electrical conductivity. Thus, measuring and characterizing surface finish can be considered for predicting machining performance.Surface finish resulting from turning operations has traditionally received considerable research attention, where as that of machining processes using multipoint cutters, requires attention by researchers. As these processes involve large number of parameters, it would be difficult to correlate surface finish with other parameters just by conducting experiments. Modelling helps to understand this kind of process better. Though some amount of work has been carried out to develop surface finish prediction models in the past, the effect of tool geometry has received little attention. However, the radial rake angle has a major affect on the powerconsumption apart from tangential and radial forces. It also influences chip curling and modifies chip flow direction. In addition to this, researchers [1] have also observed that the nose radius plays a significant role in affecting the surface finish. Therefore the development of a good model should involve the radial rake angle and nose radius along with other relevant factors.Establishment of efficient machining parameters has been a problem that has confronted manufacturing industries for nearly a century, and is still the subject of many studies. Obtaining optimum machining parameters is of great concern in manufacturing industries, where the economy of machining operation plays a key role in the competitive market. In material removal processes, an improper selection of cutting conditions cause surfaces with high roughness and dimensional errors, and it is even possible that dynamic phenomena due to auto excited vibrations may set in [2]. In view of the significant role that the milling operation plays in today‟s manufacturing world, there is a need to optimize the machining parameters for this operation. So, an effort has been made in this paper to see the influence of tool geometry(radial rake angle and nose radius) and cutting conditions(cutting speed and feed rate) on the surface finish produced during end milling of medium carbon steel. The experimental results of this work will be used to relate cutting speed, feed rate, radial rake angle and nose radius with the machining response i.e. surface roughness by modelling. The mathematical models thus developed are further utilized to find the optimum process parameters using genetic algorithms.2 ReviewProcess modelling and optimization are two important issues in manufacturing. The manufacturing processes are characterized by a multiplicity of dynamically interacting process variables. Surface finish has been an important factor of machining in predicting performance of any machining operation. In order to develop and optimize a surface roughness model, it is essential to understand the current status of work in this area.Davis et al. [3] have investigated the cutting performance of five end mills having various helix angles. Cutting tests were performed on aluminium alloy L 65 for three milling processes (face, slot and side), in which cutting force, surface roughness and concavity of a machined plane surface were measured. The central composite design was used to decide on the number of experiments to be conducted. The cutting performance of the end mills was assessed using variance analysis. The affects of spindle speed, depth of cut and feed rate on the cutting force and surface roughness were studied. The investigation showed that end mills with left hand helix angles are generally less cost effective than those with right hand helix angles. There is no significant difference between up milling and down milling with regard tothe cutting force, although the difference between them regarding the surface roughness was large. Bayoumi et al. [4]have studied the affect of the tool rotation angle, feed rate and cutting speed on the mechanistic process parameters (pressure, friction parameter) for end milling operation with three commercially available workpiece materials, 11 L 17 free machining steel, 62- 35-3 free machining brass and 2024 aluminium using a single fluted HSS milling cutter. It has been found that pressure and friction act on the chip – tool interface decrease with the increase of feed rate and with the decrease of the flow angle, while the cutting speed has a negligible effect on some of the material dependent parameters. Process parameters are summarized into empirical equations as functions of feed rate and tool rotation angle for each work material. However, researchers have not taken into account the effects of cutting conditions and tool geometry simultaneously; besides these studies have not considered the optimization of the cutting process.As end milling is a process which involves a large number f parameters, combined influence of the significant parameters an only be obtained by modelling. Mansour and Abdallaet al. [5] have developed a surface roughness model for the end milling of EN32M (a semi-free cutting carbon case hardening steel with improved merchantability). The mathematical model has been developed in terms of cutting speed, feed rate and axial depth of cut. The affect of these parameters on the surface roughness has been carried out using response surface methodology (RSM). A first order equation covering the speed range of 30–35 m/min and a second order equation covering the speed range of 24–38 m/min were developed under dry machining conditions. Alauddin et al. [6] developed a surface roughness model using RSM for the end milling of 190 BHN steel. First and second order models were constructed along with contour graphs for the selection of the proper combination of cutting speed and feed to increase the metal removal rate without sacrificing surface quality. Hasmi et al. [7] also used the RSM model for assessing the influence of the workpiece material on the surface roughness of the machined surfaces. The model was developed for milling operation by conducting experiments on steel specimens. The expression shows, the relationship between the surface roughness and the various parameters; namely, the cutting speed, feed and depth of cut. The above models have not considered the affect of tool geometry on surface roughness.Since the turn of the century quite a large number of attempts have been made to find optimum values of machining parameters. Uses of many methods have been reported in the literature to solve optimization problems for machining parameters. Jain and Jain [8] have used neural networks for modeling and optimizing the machining conditions. The results have been validated by comparing the optimized machining conditions obtained using genetic algorithms. Suresh et al. [9] have developed a surface roughness prediction model for turning mild steel using a response surface methodology to produce the factor affects of the individual process parameters. They have also optimized the turning process using the surface roughness prediction model as theobjective function. Considering the above, an attempt has been made in this work to develop a surface roughness model with tool geometry and cutting conditions on the basis of experimental results and then optimize it for the selection of these parameters within the given constraints in the end milling operation.3 MethodologyIn this work, mathematical models have been developed using experimental results with the help of response surface methodolog y. The purpose of developing mathematical models relating the machining responses and their factors is to facilitate the optimization of the machining process. This mathematical model has been used as an objective function and the optimization was carried out with the help of genetic algorithms.3.1 Mathematical formulationResponse surface methodology(RSM) is a combination of mathematical and statistical techniques useful for modelling and analyzing the problems in which several independent variables influence a dependent variable or response. The mathematical models commonly used are represented by:where Y is the machining response, ϕ is the response function and S, f , α, r are milling variables and ∈ is the error which is normally distributed about the observed response Y with zero mean.The relationship between surface roughness and other independent variables can be represented as follows，where C is a constant and a, b, c and d are exponents.To facilitate the determination of constants and exponents, this mathematical model will have to be linearized by performing a logarithmic transformation as follows:The constants and exponents C, a, b, c and d can be determined by the method of least squares. The first order linear model, developed from the above functional relationship using least squares method, can be represented as follows:where Y1 is the estimated response based on the first-order equation, Y is the measured surface roughness on a logarithmic scale, x0 = 1 (dummy variable), x1, x2, x3 and x4 are logarithmic transformations of cutting speed, feed rate, radial rake angle and nose radius respectively, ∈is the experimental error and b values are the estimates of corresponding parameters.The general second order polynomial response is as given below:where Y2 is the estimated response based on the second order equation. The parameters, i.e. b0, b1, b2, b3, b4, b12, b23, b14, etc. are to be estimated by the method of least squares. Validity ofthe selected model used for optimizing the process parameters has been tested with the help of statistical tests, such as F-test, chi square test, etc. [10].3.2 Optimization using genetic algorithmsMost of the researchers have used traditional optimization techniques for solving machining problems. The traditional methods of optimization and search do not fare well over a broad spectrum of problem domains. Traditional techniques are not efficient when the practical search space is too large. These algorithms are not robust. They are inclined to obtain a local optimal solution. Numerous constraints and number of passes make the machining optimization problem more complicated. So, it was decided to employ genetic algorithms as an optimization technique. GA come under the class of non-traditional search and optimization techniques. GA are different from traditional optimization techniques in the following ways:1.GA work with a coding of the parameter set, not the parameter themselves.2.GA search from a population of points and not a single point.3.GA use information of fitness function, not derivatives or other auxiliary knowledge.4.GA use probabilistic transition rules not deterministic rules.5.It is very likely that the expected GA solution will be the global solution.Genetic algorithms (GA) form a class of adaptive heuristics based on principles derived from the dynamics of natural population genetics. The searching process simulates the natural evaluation of biological creatures and turns out to be an intelligent exploitation of a random search. The mechanics of a GA is simple, involving copying of binary strings. Simplicity of operation and computational efficiency are the two main attractions of the genetic algorithmic approach. The computations are carried out in three stages to get a result in one generation or iteration. The three stages are reproduction, crossover and mutation.In order to use GA to solve any problem, the variable is typically encoded into a string (binary coding) or chromosome structure which represents a possible solution to the given problem. GA begin with a population of strings (individuals) created at random. The fitness of each individual string is evaluated with respect to the given objective function. Then this initial population is operated on by three main operators – reproduction cross over and mutation– to create, hopefully, a better population. Highly fit individuals or solutions are given the opportunity to reproduce by exchanging pieces of their genetic information, in the crossover procedure, with other highly fit individuals. This produces new “offspring” solutions, which share some characteristics taken from both the parents. Mutation is often applied after crossover by altering some genes (i.e. bits) in the offspring. The offspring can either replace the whole population (generational approach) or replace less fit individuals (steady state approach). This new population is further evaluated andtested for some termination criteria. The reproduction-cross over mutation- evaluation cycle is repeated until the termination criteria are met.4 Experimental detailsFor developing models on the basis of experimental data, careful planning of experimentation is essential. The factors considered for experimentation and analysis were cutting speed, feed rate, radial rake angle and nose radius.4.1 Experimental designThe design of experimentation has a major affect on the number of experiments needed. Therefore it is essential to have a well designed set of experiments. The range of values of each factor was set at three different levels, namely low, medium and high as shown in Table 1. Based on this, a total number of 81 experiments (full factorial design), each having a combination of different levels of factors, as shown in Table 2, were carried out.The variables were coded by taking into account the capacity and limiting cutting conditions of the milling machine. The coded values of variables, to be used in Eqs. 3 and 4, were obtained from the following transforming equations:where x1 is the coded value of cutting speed (S), x2 is the coded value of the feed rate ( f ), x3 is the coded value of radial rake angle(α) and x4 is the coded value of nose radius (r).4.2 ExperimentationA high precision …Rambaudi Rammatic 500‟ CNC milling machine, with a vertical milling head, was used for experimentation. The control system is a CNC FIDIA-12 compact. The cutting tools, used for the experimentation, were solid coated carbide end mill cutters of different radial rake angles and nose radii (WIDIA: DIA20 X FL38 X OAL 102 MM). The tools are coated with TiAlN coating. The hardness, density and transverse rupture strength are 1570 HV 30, 14.5 gm/cm3 and 3800 N/mm2 respectively.AISI 1045 steel specimens of 100×75 mm and 20 mm thickness were used in the present study. All the specimens were annealed, by holding them at 850 ◦C for one hour and then cooling them in a furnace. The chemical analysis of specimens is presented in Table 3. The hardness of the workpiece material is 170 BHN. All the experiments were carried out at a constant axial depth of cut of 20 mm and a radial depth of cut of 1 mm. The surface roughness (response) was measured with Talysurf-6 at a 0.8 mm cut-off value. An average of four measurements was used as a response value.5 Results and discussionThe influences of cutting speed, feed rate, radial rake angle and nose radius have been assessed by conducting experiments. The variation of machining response with respect to the variables was shown graphically in Fig. 1. It is seen from these figures that of the four dependent parameters, radial rake angle has definite influence on the roughness of the surface machined using an end mill cutter. It is felt that the prominent influence of radial rake angle on the surface generation could be due to the fact that any change in the radial rake angle changes the sharpness of the cutting edge on the periphery, i.e changes the contact length between the chip and workpiece surface. Also it is evident from the plots that as the radial rake angle changes from 4◦to 16◦, the surface roughness decreases and then increases. Therefore, it may be concluded here that the radial rake angle in the range of 4◦to 10◦would give a better surface finish. Figure 1 also shows that the surface roughness decreases first and then increases with the increase in the nose radius. This shows that there is a scope for finding the optimum value of the radial rake angle and nose radius for obtaining the best possible quality of the surface. It was also found that the surface roughness decreases with an increase in cutting speed and increases as feed rate increases. It could also be observed that the surface roughness was a minimum at the 250 m/min speed, 200 mm/min feed rate, 10◦radial rake angle and 0.8 mm nose radius. In order to understand the process better, the experimental results can be used to develop mathematical models using RSM. In this work, a commercially available mathematical software package (MATLAB) was used for the computation of the regression of constants and exponents.5.1 The roughness modelUsing experimental results, empirical equations have been obtained to estimate surface roughness with the significant parameters considered for the experimentation i.e. cutting speed, feed rate, radial rake angle and nose radius. The first order model obtained from the above functional relationship using the RSM method is as follows:The transformed equation of surface roughness prediction is as follows:Equation 10 is derived from Eq. 9 by substituting the coded values of x1, x2, x3 and x4 in terms of ln s, ln f , lnαand ln r. The analysis of the variance (ANOVA) and the F-ratio test have been performed to justify the accuracy of the fit for the mathematical model. Since the calculated values of the F-ratio are less than the standard values of the F-ratio for surface roughness as shown in Table 4, the model is adequate at 99% confidence level to represent the relationship between the machining response and the considered machining parameters of the end milling process.The multiple regression coefficient of the first order model was found to be 0.5839. This shows that the first order model can explain the variation in surface roughness to the extent of58.39%. As the first order model has low predictability, the second order model has been developed to see whether it can represent better or not.The second order surface roughness model thus developed is as given below:where Y2 is the estimated response of the surface roughness on a logarithmic scale, x1, x2, x3 and x4 are the logarithmic transformation of speed, feed, radial rake angle and nose radius. The data of analysis of variance for the second order surface roughness model is shown in Table 5.Since F cal is greater than F0.01, there is a definite relationship between the response variable and independent variable at 99% confidence level. The multiple regression coefficient of the second order model was found to be 0.9596. On the basis of the multiple regression coefficient (R2), it can be concluded that the second order model was adequate to represent this process. Hence the second order model was considered as an objective function for optimization using genetic algorithms. This second order model was also validated using the chi square test. The calculated chi square value of the model was 0.1493 and them tabulated value at χ2 0.005 is 52.34, as shown in Table 6, which indicates that 99.5% of the variability in surface roughness was explained by this model.Using the second order model, the surface roughness of the components produced by end milling can be estimated with reasonable accuracy. This model would be optimized using genetic algorithms (GA).5.2 The optimization of end millingOptimization of machining parameters not only increases the utility for machining economics, but also the product quality toa great extent. In this context an effort has been made to estimate the optimum tool geometry and machining conditions to produce the best possible surface quality within the constraints.The constrained optimization problem is stated as follows: Minimize Ra using the model given here:where xil and xiu are the upper and lower bounds of process variables xi and x1, x2, x3, x4 are logarithmic transformation of cutting speed, feed, radial rake angle and nose radius.The GA code was developed using MATLAB. This approach makes a binary coding system to represent the variables cutting speed (S), feed rate ( f ), radial rake angle (α) and nose radius (r), i.e. each of these variables is represented by a ten bit binary equivalent, limiting the total string length to 40. It is known as a chromosome. The variables are represented as genes (substrings) in the chromosome. The randomly generated 20 such chromosomes (population size is 20), fulfillingthe constraints on the variables, are taken in each generation. The first generation is called the initial population. Once the coding of the variables has been done, then the actual decoded values for the variables are estimated using the following formula:where xi is the actual decoded value of the cutting speed, feed rate, radial rake angle and nose radius, x(L) i is the lower limit and x(U) i is the upper limit and li is the substring length, which is equal to ten in this case.Using the present generation of 20 chromosomes, fitness values are calculated by the following transformation:where f(x) is the fitness function and Ra is the objective function.Out of these 20 fitness values, four are chosen using the roulette-wheel selection scheme. The chromosomes corresponding to these four fitness values are taken as parents. Then the crossover and mutation reproduction methods are applied to generate 20 new chromosomes for the next generation. This processof generating the new population from the old population is called one generation. Many such generations are run till the maximum number of generations is met or the average of four selected fitness values in each generation becomes steady. This ensures that the optimization of all the variables (cutting speed, feed rate, radial rake angle and nose radius) is carried out simultaneously. The final statistics are displayed at the end of all iterations. In order to optimize the present problem using GA, the following parameters have been selected to obtain the best possible solution with the least computational effort:Table 7 shows some of the minimum values of the surface roughness predicted by the GA program with respect to input machining ranges, and Table 8 shows the optimum machining conditions for the corresponding minimum values of the surface roughness shown in Table 7. The MRR given in Table 8 was calculated bywhere f is the table feed (mm/min), aa is the axial depth of cut (20 mm) and ar is the radial depth of cut (1 mm).It can be concluded from the optimization results of the GA program that it is possible to select a combination of cutting speed, feed rate, radial rake angle and nose radius for achieving the best possible surface finish giving a reasonably good material removal rate. This GA program provides optimum machining conditions for the corresponding given minimum values of the surface roughness. The application of the genetic algorithmic approach to obtain optimal machining conditions will be quite useful at the computer aided process planning (CAPP) stage in the production of high quality goods with tight tolerances by a variety of machining operations, and in the adaptive control of automated machine tools. With the known boundaries of surface roughness and machining conditions, machining could be performed with a relatively high rate of success with the selected machining conditions.6 ConclusionsThe investigations of this study indicate that the parameters cutting speed, feed, radial rake angle and nose radius are the primary actors influencing the surface roughness of medium carbon steel uring end milling. The approach presented in this paper provides n impetus to develop analytical models, based on experimental results for obtaining a surface roughness model using the response surface methodology. By incorporating the cutter geometry in the model, the validity of the model has been enhanced. The optimization of this model using genetic algorithms has resulted in a fairly useful method of obtaining machining parameters in order to obtain the best possible surface quality.中文翻译选择最佳工具，几何形状和切削条件利用表面粗糙度预测模型端铣摘要：刀具几何形状对工件表面质量产生的影响是人所共知的，因此，任何成型面端铣设计应包括刀具的几何形状。
外文翻译--机械设计简介
外文原文Introduction to Mechanical DesignMechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product.People who perform the various functions of mechanical design are typically called designers, or design engineers. Mechanical design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.As stated previously, the purpose of mechanical design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed.Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design. On the other hand, any calculation made must be done with the utmost care and precision. For example, if a decimal point is misplaced, a otherwise acceptable design may mot function.Good designs require trying mew ideas and being willing to take a certain amount of risk, knowing that if the mew idea does not work the existing method can bereinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.New designs generally have “bugs” or unforeseen which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate then in the early stages of design before firm details are required by manufacturing. In this way, Innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they ate to be incorporated. Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer whenpresenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.Basically, there ate only three means of communication available to us. These are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, no one will ever know how competent that person is!The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great deal to learn from a failure, and the greatest gains ate obtained by those wiling to risk defeat. In the final analysis, the real failure would lie in decoding not to make the presentation at all. To communicate effectively, the following questions must be answered:1、Does the design really serve a human need?2、Will it be competitive with existing products of rival companies?3、It is economical to profit?4、Can it be readily maintained?5、Will it sell and make a profit?Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings.Quite often, a problem will occur during the manufacturing cycle. It may be that a exchange is required in the dimensioning or tolerancing of a part so that it can be more readily produced. This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly ortesting just prior to shipping.Engineering design is a systematic process by which solutions to the needs of humankind are obtained. The process is applied to problems (needs) of varying complexity. For example, mechanical engineers will use the design process to find an effective, efficient method to convert reciprocating motion to circular motion for the drive train in an internal combustion engine; electrical engineers will use the process to design electrical generating systems using falling water as the power source; and materials engineers use the process to design ablative materials which enable astronauts to safely the earth’s atmosphere.The va st majority of complex problems in today’s high technology society depend for solution not on a single engineering discipline, but on teams of engineers, scientists, environmentalists, economists, sociologists, and legal personnel. Solutions are not only dependent upon the appropriate applications of technology but also upon public sentiment, government regulations and political influence. As engineers we are empowered with the technical expertise to develop new and improved products and systems, but at the same time we must be increasingly aware of the impact of our actions on society and the environment in general and work conscientiously toward the best solution in view of all relevant factors.Design is the culmination of the engineering educational process; it is the salient feature that distinguishes engineering from other professions.A formal definition of engineering design is found in the curriculum guidelines of the Accreditation Board for Engineering and Technology (AENT). ABEN accredits curricula in engineering schools and derives its membership from the various engineering professional societies. Each accredited curriculum has a well-deigned design component which falls within the ABEN guideline. The ABEN statement on design reads as follows:Engineering design is the process of devising a system, component, or process to meet desired needs. It is a decision making process (often iterative ), in which the basic sciences, mathematic, and engineering sciences are applied to convert resources optimally to meet a stated objective. Among the fundamental elements of the designprocess are the establishment of objectives and criteria, synthesis, analysis, construction, testing, and evaluation. The engineering design component of a curriculum must include most of the following features: development of student creativity, use of open-ended problems, development and use of modern design theory mad methodology, formulation of design problem statements and specifications, consideration of alternative solutions, feasibility considerations, production processes, concurrent engineering design, and detailed system descriptions. Further, it is essential to include a variety of realistic constraints such as economic factors, safety, reliability, aesthetics, ethics, and social impact.If anything can be said about the last half of the twentieth century, it is that we have had an explosion of information. The amount of data that can be uncovered on most subjects is overwhelming. People in the upper levels of most organizations have assistants who condense most of the things that they must read, hear, or watch. When you begin a search for information, be prepared to scan many of your sources and document their location so that you can find them easily if the date subsequently appear to be important.Some of the sources that are available include the following:1、Exiting solutions. Much can be learned from the current status of solutions toa specific need if actual products can be located, studied and, in some cases, purchased for detailed analysis. An improved solution or an innovative new solution new solution cannot be found unless the existing solutions are thoroughly understood.2、Your library. Many universities have courses that teach you how to use your library. Such courses are easy when you compare them with those in chemistry and calculus, but their importance should not be underestimated. There are many sources in the library that can lead you to the information that you are seeking. You may find what you need in an index such as the Engineering Index. There are many other indexes that provide specialized information. The nature of your problem will direct which ones may be helpful to you. Don’t hesitate to ask for assistance from the librarian. You should use to advantage the computer databases found in libraries and often available through CD-ROM technology.3、Professional organizations. The American Society of Mechanical Engineers isa technical society that will be of interest to students majoring in mechanical engineering. Each major in your college is associated with not one but often several such societies. The National Society of Professional Engineers is an organization that most engineering students well eventually join, as well as at least one technical society such as the society of manufacturing engineers, the American Society of civil engineers (ASCE), or any one of dozens that serve the technical interests of the host of specialties with which professional practices seem most closely associated. May engineers are members of several associations and societies.4、Trade journals. They are published by the hundreds, usually specializing in certain classes of products and services. Money and economics are part of engineering design and decision making. We live in a society that is based on economics and competition. It is no doubt true that many good ideas never get tried because they are deemed to be economically infeasible. Most of us have been aware of this condition in our daily lives. We started with our parents explaining why we could not have some item that we wanted because it cost too much. Likewise, we will not put some very desirable component into our designs because the value gained will not return enough profit in relation to its cost.Industry is continually looking for new products of all types. Some are desired because the current product is not competing well in the marketplace. Others are tried simply because it appears that people will buy them. How do manufacturers know that a new product will be popular? They seldom know with certainty. Statistics is an important consideration in market analysis. Most of you will find that probability and statistics are an integral part of your chosen engineering curriculum. The techniques of this area of mathematics allow us to make inferences about how large groups of people react based on the reactions of a few.中文译文机械设计简介机械设计是为了满足人类需要而制定出的新产品或者改进旧产品时对科学与技术的应用。
机械毕业设计英文外文翻译213机械设计基础
附录(外文翻译——原文)Fundamentals of Mechanical DesignMechanical design means the design of things and systems of a mechanical nature—machines, products, structures, devices, and instruments. For the most part mechanical design utilizes mathematics, the materials sciences, and the engineering-mechanics sciences.The total design process is of interest to us. How does it begin? Does the engineer simply sit down at his desk with a blank sheet of paper? And, as he jots down some ideas, what happens next? What factors influence or control the decisions which have to be made? Finally, then, how does this design process end?Sometimes, but not always, design begins when an engineer recognizes a need and decides to do something about it. Recognition of the need and phrasing it in so many words often constitute a highly creative act because the need may be only a vague discontent, a feeling of uneasiness, of a sensing that something is not right.The need is usually not evident at all. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by the variations in package weight, and by slight but perceptible variations in the quality of the packaging or wrap.There is a distinct difference between the statement of the need and the identification of the problem. which follows this statement. The problem is more specific. If the need is for cleaner air, the problem might be that of reducing the dust discharge from power-plant stacks, or reducing the quantity of irritants from automotive exhausts.Definition of the problem must include all the specifications for the thing that is to be designed. The specifications are the input and output quantities, the characteristics of the space the thing must occupy and all the limitations on these quantities. We can regard the thing to be designed as something in a black box. In this case we must specify the inputs and outputs of the box together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and the reliability.There are many implied specifications which result either from the designer's particular environment or from the nature of the problem itself. The manufacturing processes which are available, together with the facilities of a certain plant, constitute restrictions on a designer's freedom, and hence are a part of the implied specifications. A small plant, for instance, may not own cold-working machinery. Knowing this, the designer selects other metal-processing methods which can be performed in the plant. The labor skills available and the competitive situation also constitute implied specifications.After the problem has been defined and a set of written and implied specifications has been obtained, the next step in design is the synthesis of an optimum solution. Now synthesis cannot take place without both analysis and optimization because the system under design must be analyzed to determine whether the performance complies with the specifications.The design is an iterative process in which we proceed through several steps, evaluate theresults, and then return to an earlier phase of the procedure. Thus we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. Both analysis and optimization require that we construct or devise abstract models of the system which will admit some form of mathematical analysis. We call these models mathematical models. In creating them it is our hope that we can find one which will simulate the real physical system very well.Evaluation is a significant phase of the total design process. Evaluation is the final proof of a successful design, which usually involves the testing of a prototype in the laboratory. Here we wish to discover if the design really satisfies the need or needs. Is it reliable? Will it compete successfully with similar products? Is it economical to manufacture and to use? Is it easily maintained and adjusted? Can a profit be made from its sale or use?Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.Basically, there are only three means of communication available to us. There are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, no one will ever know how competent that person is!The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great to be learned from a failure, and the greatest gains are obtained by those willing to risk defeat. In the find analysis, the real failure would lie in deciding not to make the presentation at all.Introduction to Machine DesignMachine design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product.People who perform the various functions of machine design are typically called designers, or design engineers. Machine design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.As stated previously, the purpose of machine design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed.Machine design should be considered to be an opportunity to use innovative talents to envision a design of a product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions to produce a good design. On the other hand, any calculations made must be done with the utmost care and precision. For example, if a decimal point is misplaced, an otherwise acceptable design may not function.Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that is the new idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated.New designs generally have “bugs” or unforeseen problems which mu st be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Initially the designer must communicate a preliminary design to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and written material. To communicate effectively, the following questions must be answered:(1)Does the design really serve a human need?(2)Will it be competitive with existing products of rival companies?(3)Is it economical to produce?(4)Can it be readily maintained?(5)Will it sell and make a profit?Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detailand assembly drawings.Quite often, a problem well occur during the manufacturing cycle. It may be that a change is required in the dimensioning or tolerancing of a part so that it can be more readily produced. This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These realities simply bear out the fact that design is a living process. There is always a better way to do it and the designer should constantly strive towards finding that better way.MachiningTurning The engine lathe, one of the oldest metal removal machines, has a number of useful and highly desirable attributes. Today these lathes are used primarily in small shops where smaller quantities rather than large production runs are encountered.The engine lathe has been replaced in today's production shops by a wide variety of automatic lathes such as automatic of single-point tooling for maximum metal removal, and the use of form tools for finish and accuracy, are now at the designer's fingertips with production speeds on a par with the fastest processing equipment on the scene today.Tolerances for the engine lathe depend primarily on the skill of the operator. The design engineer must be careful in using tolerances of an experimental part that has been produced on the engine lathe by a skilled operator. In redesigning an experimental part for production, economical tolerances should be used.Turret Lathes Production machining equipment must be evaluated now, more than ever before, in terms of ability to repeat accurately and rapidly. Applying this criterion for establishing the production qualification of a specific method, the turret lathe merits a high rating.In designing for low quantities such as 100 or 200 parts, it is most economical to use the turret lathe. In achieving the optimum tolerances possible on the turret lathe, the designer should strive for a minimum of operations.Automatic Screw Machines Generally, automatic screw machines fall into several categories; single-spindle automatics, multiple-spindle automatics and automatic chucking machines. Originally designed for rapid, automatic production of screws and similar threaded parts, the automatic screw machine has long since exceeded the confines of this narrow field, and today plays a vital role in the mass production of a variety of precision parts. Quantities play an important part in the economy of the parts machined on the automatic to set up on the turret lathe than on the automatic screw machine. Quantities less than 1000 parts may be more economical to set up on the turret lathe than on the automatic screw machine. The cost of the parts machined can be reduced if the minimum economical lot size is calculated and the proper machine is selected for these quantities.Automatic Tracer Lathes Since surface roughness depends greatly upon material turned, tooling ,and fees and speeds employed, minimum tolerances that can be held on automatic tracer lathes are not necessarily the most economical tolerances.Is some case, tolerances of ±0.05mm are held in continuous production using but one cut. Groove width can be held to ±0.125mm on some parts. Bores and single-point finishes can be held to ±0.0125mm. On high-production runs where maximum output is desirable, a minimum tolerance of ±0.125mm is economical on both diameter and length of turn.Milling With the exceptions of turning and drilling, milling is undoubtedly the most widely used method of removing metal. Well suited and readily adapted to the economical production of any quantity of parts, the almost unlimited versatility of the milling process merits the attention and consideration of designers seriously concerned with the manufacture of their product.As in any other process, parts that have to be milled should be designed with economical tolerances that can be achieved in production milling. If the part is designed with tolerances finer than necessary, additional operations will have to be added to achieve these tolerances——and this will increase the cost of the part.Grinding Grinding is one of the most widely used methods of finishing parts to extremely close tolerances and low surface roughness. Currently, there are grinders for almost for almost every type of grinding operation. Particular design features of a part dictate to a large degree the type of grinding machine required. Where processing costs are excessive, parts redesigned to utilize a less expensive, higher output grinding method may be well worthwhile. For example, wherever possible the production economy of centerless grinding should be taken advantage of by proper design consideration.Although grinding is usually considered a finishing operation, it is often employed as a complete machining process on work which can be ground down from rough condition without being turned or otherwise machined. Thus many types of forgings and other parts are finished completely with the grinding wheel at appreciable savings of time and expense.Classes of grinding machines include the following: cylindrical grinders, centerless grinders, internal grinders, surface grinders, and tool and cutter grinders.The cylindrical and centerless grinders are for straight cylindrical or taper work; thus splines, shafts, and similar parts are ground on cylindrical machines either of the common-center type or the centerless machine.Thread grinders are used for grinding precision threads for thread gages, and threads on precision parts where the concentricity between the diameter of the shaft and the pitch diameter of the thread must be held to close tolerances.The internal grinders are used for grinding of precision holes, cylinder bores, and similar operations where bores of all kinds are to be finished.The surface grinders are for finishing all kinds of flat work, or work with plain surfaces which may be operated upon either by the edge of a wheel or by the face of a grinding wheel. These machines may have reciprocating or rotating tables.(外文翻译——汉文)机械设计基础机械设计基础是指机械装置和机械系统——机器、产品、结构、设备和仪器的设计。
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机械设计是一门通过设计新产品或者改进老产品来满足人类需求的应用技术科学。
它涉及工程技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。
进行各种机械设计工作的人员通常被称为设计人员或者机械设计工程师。
机械设计是一项创造性的工作。
设计工程师不仅在工作上要有创造性，还必须在机械制图、运动学、工程材料、材料力学和机械制造工艺学等方面具有深厚的基础知识。
如前所诉，机械设计的目的是生产能够满足人类需求的产品。
发明、发现和科技知识本身并不一定能给人类带来好处，只有当它们被应用在产品上才能产生效益。
因而，应该认识到在一个特定的产品进行设计之前，必须先确定人们是否需要这种产品。
应当把机械设计看成是机械设计人员运用创造性的才能进行产品设计、系统分析和制定产品的制造工艺学的一个良机。
掌握工程基础知识要比熟记一些数据和公式更为重要。
仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。
另一方面，应该认真精确的进行所有运算。
例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。
一个好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险，当新的方法不适用时，就使用原来的方法。
因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。
一个全新的设计，要求屏弃许多陈旧的，为人们所熟知的方法。
由于许多人墨守成规，这样做并不是一件容易的事。
一位机械设计师应该不断地探索改进现有的产品的方法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。
新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。
因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。
应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。
在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。
即使产生了许多不切实际的想法，也会在设计的早期，即绘制图纸之前被改正掉。
只有这样，才不致于堵塞创新的思路。
通常，要提出几套设计方案，然后加以比较。
很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。
心理学家经常谈论如何使人们适应他们所操作的机器。
设计人员的基本职责是努力使机器来适应人们。
这并不是一项容易的工作，因为实际上并不存在着一个对所有人来说都是最优的操作范围和操作过程。
另一个重要问题，设计工程师必须能够同其他有关人员进行交流和磋商。
在开始阶段，设计人员必须就初步设计同管理人员进行交流和磋商，并得到批准。
这一般是通过口头讨论，草图和文字材料进行的。
为了进行有效的交流，需要解决下列问题：（1）所设计的这个产品是否真正为人们所需要？（2）此产品与其他公司的现有同类产品相比有无竞争能力？（3）生产这种产品是否经济？（4）产品的维修是否方便？（5）产品有无销路？是否可以盈利？只有时间能对上述问题给出正确答案。
但是，产品的设计、制造和销售只能在对上述问题的初步肯定答案的基础上进行。
设计工程师还应该通过零件图和装配图，与制造部门一起对最终设计方案进行磋商。
通常，在制造过程中会出现某个问题。
可能会要求对某个零件尺寸或公差作一些更改，使零件的生产变得容易。
但是，工程上的更改必须要经过设计人员批准，以保证不会损伤产品的功能。
有时，在产品的装配时或者装箱外运前的试验中才发现设计中的某种缺陷。
这些事例恰好说明了设计是一个动态过程。
总是存在着更好的方法来完成设计工作，设计人员应该不断努力，寻找这些更好的方法。
近些年来，工程材料的选择已经显得重要。
此外，选择过程应该是一个对材料的连续不断的重新评价过程。
新材料不断出现，而一些原有的材料的能够获得的数量可能会减少。
环境污染、材料的回收利用、工人的健康及安全等方面经常会对材料选择附加新的限制条件。
为了减轻重量或者节约能源，可能会要求使用不同的材料。
来自国内和国际竞争、对产品维修保养方便性要求的提高和顾客的反馈等方面的压力，都会促使人们对材料进行重新评价。
由于材料选用不当造成的产品责任诉讼，已经产生了深刻的影响。
此外，材料与材料加工之间的相互依赖关系已经被人们认识得更清楚。
因此，为了能在合理的成本和确保质量的前提下获得满意的结果，设计工程师的制造工程师都必须认真仔细地选择、确定和使用材料。
制造任何产品的第一步工作都是设计。
设计通常可以分为几个明确的阶段：（a）初步设计；（b）功能设计；（c）生产设计。
在初步设计阶段，设计者着重考虑产品应该具有的功能。
通常要设想和考虑几个方案，然后决定这种思想是否可行；如果可行，则应该对其中一个或几个方案作进一步的改进。
在此阶段，关于材料选择唯一要考虑的问题是：是否有性能符合要求的材料可供选择；如果没有的话，是否有较大的把握在成本和时间都允许的限度内研制出一种新材料。
在功能设计和工程设计阶段，要做出一个切实可行的设计。
在这个阶段要绘制出相当完整的图纸，选择并确定各种零件的材料。
通常要制造出样机或者实物模型，并对其进行试验，评价产品的功能、可靠性、外观和维修保养性等。
虽然这种试验可能会表明，在产品进入到生产阶段之前，应该更换某些材料，但是，绝对不能将这一点作为不认真选择材料的借口。
应该结合产品的功能，认真仔细地考虑产品的外观、成本和可靠性。
一个很有成就的公司在制造所有的样机时，所选用的材料应该和其生产中使用的材料相同，并尽可能使用同样的制造技术。
这样对公司是很有好处的。
功能完备的样机如果不能根据预期的销售量经济地制造出来，或者是样机与正式生产的装置在质量和可靠性方面有很大不同，则这种样机就没有多大的价值。
设计工程师最好能在这一阶段完全完成材料的分析、选择和确定工作，而不是将其留到生产设计阶段去做。
因为，在生产设计阶段材料的更换是由其他人进行的，这些人对产品的所有功能的了解不如设计工程师。
在生产设计阶段中，与材料有关的主要问题是应该把材料完全确定下来，使它们与现有的设备相适应，能够利用现有设备经济地进行加工，而且材料的数量能够比较容易保证供应。
在制造过程中，不可避免地会出现对使用中的材料做一些更改的情况。
经验表明，可采用某些便宜材料作为替代品。
然而，在大多数情况下，在进行生产以后改换材料要比在开始生产前改换材料所花费的代价要高。
在设计阶段做好材料选择工作，可以避免多数这样的情况。
在生产制造开始后出现了可供使用的新材料是更换材料的最常见的原因。
当然，这些新材料可能降低成本、改进产品的性能。
但是，必须对新材料进行认真的评价，以确保其所有性能都满足要求。
应当记住，新材料的性能和可靠性很少像现有材料那样为人们所了解。
大部分的产品失效和产品责任事故案件是由于在选用新材料作为替代材料之前，没有真正了解它们的长期使用性能而引起的。
产品的责任诉讼迫使设计人员和公司在选择材料时，采用最好的程序。
在材料过程中，五个最常见的问题为：（a）不了解或者不会使用关于材料应用方面的最新最好的信息资料；(b)未能预见和考虑擦黑年品可能的合理用途（如有可能，设计人员还应进一步预测和考虑由于产品使用方法不当造成的后果。
在近年来的许多产品责任诉讼案件中，由于错误地使用产品而受到伤害的原告控告生产厂家，并且赢得判决）；(c)所使用的材料的数据不全或是有些数据不确定，尤其是当其长期性能数据是如此的时候；(d)质量控制方法不适当和未经验证；(e)由一些完全不称职的人员选择材料。
通过对上述五个问题的分析，可以得出这些问题是没有充分理由存在的结论。
对这些问题的研究分析可以为避免这些问题的出现指明方向。
尽管采用最好的材料选择方法也不能避免发生产品责任诉讼，设计人员和工业界按照适当的程序进行材料选择，可以大大减少诉讼的数量。
从以上的讨论可以看出，选择材料的人们应该对材料的性质，特点和加工方法有一个全面而基本的了解。
Machine design theoryThe machine design is through designs the new product or improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question.Carries on each kind of machine design work to be usually called designs the personnel or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge.If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of productMust regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainlyis not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea.Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the question are solved, can manifest new goods come into the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itself does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method.In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel''s basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process.Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. In order to carry on the effective exchange, needs to solve the following problem:(1) designs whether this product truly does need for the people? Whether there is competitive ability(2) does this product compare with other companies'' existing similar products?(3) produces this kind of product is whether economical?(4) product service is whether convenient?(5) product whether there is sale? Whether may gain?Only has the time to be able to produce the correct answer to above question. But, the product design, the manufacture and the sale only can in carry on to the above question preliminary affirmation answer foundation in. Project engineer also should through the detail drawing and the assembly drawing, carries on the consultation together with the branch of manufacture to the finally design proposal.Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the components the production to change easily. But, in the project change must have to pass through designs the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembly or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instances exactly showed the design is a dynamic process. Always has a better method to complete the design work, designs the personnel to be supposed unceasingly diligently, seeks these better method.Recent year, the engineerig material choice already appeared importantly. In addition, the choice process should be to the material continuously the unceasing again appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The environmental pollution, material recycling aspect and so on use, worker''s health and security frequently can attach the new limiting condition to the choice of material. In order to reduce the weight or saves the energy, possibly can request the use different material. Comes from domestic and international competition, to product service maintenance convenience request enhancement and customer''s aspect the and so on feedback pressure, can urge the people to carry on to the material reappraises. Because the material does not select when created the product responsibility lawsuit, has already had the profound influence. In addition, the material and between the material processing interdependence is already known by the people clearly. Therefore, in order to can and guarantees the quality in the reasonable cost under the premise to obtainsatisfaction the result, project engineer makes engineers all to have earnestly carefully to choose, the determination and the use material.Makes any product the first step of work all is designs. Designs usually may divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is whether feasible; If is feasible, then should makes the further improvement to or several plans. In this stage, the question which only must consider about the choice of material is: Whether has the performance to conform to the request material to be possible to supply the choice; If no, whether has a bigger assurance all permits in the cost and the time in the limit develops one kind of new material.In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite complete blueprint in this stage, chooses and determines each kind of components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the product to the production base in front of, should replace certain materials, but, absolutely cannot this point take not earnestly chooses the material the excuse. Should unify the product the function, earnestly carefully considers the product the outward appearance, the cost and the reliability. Has the achievement very much the company when manufacture all prototypes, selects the material should the material which uses with its production in be same, and uses the similar manufacture technology as far as possible. Like this has the advantage very much to the company. The function complete prototype if cannot act according to the anticipated sales volume economically to make, or is prototypical and the official production installment has in the quality and the reliable aspect is very greatly different, then this kind of prototype does not have the great value. Project engineer is best can completely complete the material in this stage the analysis, the choice and the determination work, but is not remains it to the production design stage does. Because, is carries on in the productiondesign stage material replacement by other people, these people are inferior to project engineer to the product all functions understanding. In the production design stage, is should completely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the material quantity can quite be easy to guarantee the supply.In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certain cheap materials to take the substitute. However, in the majority situation, in will carry on the production later to change the material to have in to start before the production to change the price which the material will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situations. Started after the production manufacture to appear has been possible to supply the use the new material is replaces the material the most common reason. Certainly, these new materials possibly reduce the cost, the improvement product performance. But, must carry on the earnest appraisal to the new material, guarantees its all performance all to answer the purpose. Must remember that, the new material performance and the reliable very few pictures materials on hand such understood for the people. The majority of products expiration and the product accident caused by negligence case is because in selects the new material to take in front of substitution material, not truly understood their long-term operational performance causes.The product responsibility lawsuit forces designs the personnel and the company when the choice material, uses the best procedure. In the material process, five most common questions are: (a) did not understand or cannot use about the material application aspect most newly the best information paper; (b) has not been able to foresee and to consider the dusk year possible reasonable use (for example to have the possibility, designs the personnel also to be supposed further to forecast and the consideration because product application method not when creates consequence. ecent years many products responsibilities lawsuit case, because wrongly uses the plaintiff which the product receives the injury to accuse produces the factory, and wins the decision); (c) uses the material data not entire perhaps some data areindefinite, works as its long-term performance data is the like this time in particular;(d) the quality control method is not suitable and not after the confirmation; (e) the personnel which completely is not competent for the post by some chooses the material.Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses the appearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of material according to the suitable procedure, may greatly reduce the lawsuit the quantity.May see from the above discussion, the choice material people should to the material nature, the characteristic and the processing method have comprehensive and the basic understanding.。