机械毕业设计英文外文翻译582轴承的摩擦与润滑
轴承中英文对照外文翻译文献
中英文资料翻译(文档含英文原文和中文翻译)EXTENDING BEARING LIFEAbstract：Nature works hard to destroy bearings, but their chances of survival can be improved by following a few simple guidelines. Extreme neglect in a bearing leads to overheating and possibly seizure or, at worst, an explosion. But even a failed bearing leaves clues as to what went wrong. After a little detective work, action can be taken to avoid a repeat performance.Keywords: bearings failures lifeBearings fail for a number of reasons，but the most common are misapplication，contamination，improper lubricant，shipping or handling damage，and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrong．However，while a postmortem yields good information，it is better to avoid the process altogether by specifying the bearing correctly in The first place．To do this，it is useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing.Equally critical is a study of requirements for noise, torque, and runout, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job.1 Why bearings failAbout 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environment．Fortunately, a bearingfailure caused by environment or handling contamination is preventable，and a simple visual examination can easily identify the cause．Conducting a postmortem il1ustrates what to look for on a failed or failing bearing．Then，understanding the mechanism behind the failure, such as brinelling or fatigue, helps eliminate the source of the problem.Brinelling is one type of bearing failure easily avoided by proper handing and assembly. It is characterized by indentations in the bearing raceway caused by shock loading－such as when a bearing is dropped-or incorrect assembly. Brinelling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)．It may also be caused by improper assembly, Which places a load across the races．Raceway dents also produce noise，vibration，and increased torque.A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turning．This problem is called false brinelling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brinelling acts like an abrasive, further contaminating the bearing. Unlike brinelling, false binelling is often indicated by a reddish color from fretting corrosion in the lubricant.False brinelling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brinelling during transit.Seizures can be caused by a lack of internal clearance, improper lubrication, or excessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color，usually to blue-black or straw colored．Friction also causes stress in the retainer，which can break and hasten bearing failure．Premature material fatigue is caused by a high load or excessive preload．When these conditions are unavoidable，bearing life should be carefully calculated so that a maintenance scheme can be worked out．Another solution for fighting premature fatigue is changing material．When standard bearing materials，such as 440C or SAE 52100，do not guarantee sufficient life，specialty materials can be recommended. In addition，when the problem is traced back to excessive loading，a higher capacity bearing or different configuration may be used．Creep is less common than premature fatigue．In bearings．it is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaft．Creep can be expensive because it causes damage to other components in addition to the bearing．0ther more likely creep indicators are scratches，scuff marks，or discoloration to shaftand bore．To prevent creep damage，the bearing housing and shaft fittings should be visually checked．Misalignment is related to creep in that it is mounting related．If races are misaligned or cocked．The balls track in a noncircumferencial path．The problem is incorrect mounting or tolerancing，or insufficient squareness of the bearing mounting site．Misalignment of more than 1/4·can cause an early failure．Contaminated lubricant is often more difficult to detect than misalignment or creep．Contamination shows as premature wear．Solid contaminants become an abrasive in the lubricant．In addition。
机械工程外文翻译(适用于毕业论文外文翻译+中英文对照)
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 newEngineering –separated from the civil engineering tools andmachines on the branch-developed together with Birmingham andthe establishment of the Associantion of Mechanical Engineersin 1847 had been officially recognized.The mechanicalengineering already mainly used in by trial and error methodmechanic application technological development into professional engineer the scientific method of which in theresearch,the design and the realm of production used .From themost broad perspective,thedemend 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 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 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 largevolumes 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,threerotation,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 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 complexsurgery,and injuries and ill patients life functions can be sustained.Someenviromental 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,producingnoise,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 sciencefoundation.It includes the power and movement of the relationship dynamics For example,in the vibration and movement of the relationship;Automaticcontrol;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,thedesing 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,includeplan,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,theconsultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use thescience 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 mechanicalengineering, to take unexpected and important way to bring about a new capacity,still has a personal,markedcharacteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,suchas: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 desginincludeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnicalengineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Designstages.The entire desgin process from start to finish,in the process,a demand that is designed forit 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.Designconsiderations.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.Especiallystudents,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,forexample,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 theother point of view.Our purpose is to make those you do not be 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.Theyare:input,processingexprot.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.Forexample,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 productperformance,installation and may have to conduct further debugging in addition,someproducts,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,syntheticrubber,composite materials and ceramics.It said the production proccess is divided into several major process,includingshape,forging,casting/founding,heattreatment,fixed/connections ,measurement/ quality control and materalcutting.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 manusllyproduced.This is totally integrated production take shape.A person needsindentification,collectionmaterials,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.Onecan 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 indivdualprocesses,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 withthem .The ultimate result is the efficient working fast parked through automated processes,but is part of the stagnation in wages down,causingbottlenecks.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,sommthoperation,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 ofthe 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,morespecifically,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 ofits impact.In a more precise kinematic studies position,displacement,rotation, speed,velocity and acceleration of disciplines,foresample,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。
机械制造专业外文翻译--润滑和轴颈轴承
外文原文：LUBRICATION AND JOURNAL BEARINGS1 IntroductionA bearing can be defined as a member specifically designed to support moving machine components. The most common bearing application is the support of a rotating shaft which is transmitting power from one location to another; one example is the crankshaft bearings of automatic engine; another example is the shaft bearings used all types of electric motors. Since there is always relative motion between a bearing and its mating surface, friction is involved. In many instances, such as the design of pulleys, brakes and clutches, friction is desirable. However, in the case of bearings, the reduction of friction is one of prime considerations:friction results in loss of power, generation of heat and wear of mating surfaces.Journal and antifriction bearings are the two general types of bearings existence. Journal bearings operate with sliding contact, whereas antifriction bearings experience predominantly rolling contact. The amount of sliding friction in journal bearings depends on the surface finishes, materials, sliding velocities and the type of lubricant used. The principle motion-retarding effect in antifriction bearings is called rolling resistance rather than rolling friction. This is so because the resistance of motion is essentially due to the deformation of the rolling elements and, hence, it is not a sliding phenomenon. Antifriction bearings will be in chapter 1.4.To reduce the problems associated with sliding friction in journal bearings, a lubricant is used in conjunction with compatible mating materials. When selecting the lubricant and mating materials, one must take into account bearing pressures, temperatures and rubbing velocities.The principle function of the lubricant in sliding contact bearings is to prevent physical contact between the rubbing surfaces. Thus the maintenance of an oil film under varying loads, speeds and temperature is the prime consideration in sliding contact bearings.2 Theory of FrictionFriction is the resistance one part exerts on a second part when relative sliding motion occurs or is attempted. Thus friction takes place whenever two surfaces rub together. The cause of friction is the inevitable interlocking of the tiny irregularities of the two mating surfaces. A force is required to deform the tiny peaks and valleys topermit motion.When a block of weight W rests on a horizontal fixed surface, a force P is applied to the block. Initially, P equals zero, but its value constantly increases as a function of time. Due to friction, a force F is created between block and fixed surface. The direction of the frictional force, F, is opposite that of P, because friction always opposes motion or attempted motion. Also note that the normal force, N, acting perpendicular to the mating surface is equal and opposite to the weight, W, of the block.Rolling Contact BearingsThe concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to load; (b) stiffness, i. e. deflections under load; (c) friction;(d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will become important where loads are high, although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard to the hostility of the environment.Because the high quality and low price of ball and roller bearings depends on quantity production, the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with steel which is through-hardened to about 900 HV, although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600 HV. It is not surprising that, owing to the high stresses involved, a predominant form of failure should be metal fatigue, and a good deal of work is based on accepted values of life and it is general practice in the bearing industry to define the load capacity of the bearing as that value below which 90 per cent of a batch will exceed a life of one million revolutions.Notwithstanding the fact that responsibility for the basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of criticalimportance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by abutting against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to allow space for this.Where life is not the determining factor in design, it is usual to determine maximum loading by the amount to which a bearing will deflect under load. Thus the concept of “static load-carrying capacity” is understood to mean the load that can be applied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has been determined by practical experience as the load which when applied to a bearing results in a total deformation of the rolling-element diameter. This would correspond to a permanent deformation of 0.0025 mm for a ball 25 mm in diameter.The successful functioning of many bearings depends upon providing them with adequate protection against their environment, and in some circumstances the environment must be protected from lubricants or products of deterioration of the bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on the basis of the appropriate bearing theory.Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control (NC). Prior to the advent of NC, all machine tools were manually operated and controlled .Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather thanoperating a machine tool, an NC technician writes a program that issues operational instructions to the machine tool. For a machine tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations in manufacturing technology:1.Electrical discharge machining.ser cutting.3.Electron beam welding.Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide variety of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tools and processes.Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U. S. Air force. In its earliest stages, NC machines were able to make straight cuts efficiently and effectively.However, curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter is the straight lines making up the steps, the smoother is the curve. Each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools (APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the further development of NC technology. The original NC systems were vastly different from those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. A tape reader was usedto interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.A major problem was the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each successive time a part was produced on a machine tool, the paper tape carrying the programmed instructions had to be rerun through the reader. If it was necessary to produce 100 copies of a given part, it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than the paper taps, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it was necessary to interrupt machining operations and make a new tape .It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problems of NC associated with punched paper and plastic tape.The development of a concept known as direct numerical control (DNC) solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control .machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend on a host computer. When the lost computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.The development of the microprocessor allowed for the development ofprogrammable logic controllers (PLCs) and microcomputers. These two technologies allowed for the development of computer numerical control (CNC).With CNC, each machine tool has a PLC or a microcomputer that serves the same purpose. This allows programs to be input and stored at each individual machine tool. It also allows programs to be developed off-line and downloaded at the individual machine tool. CNC solved the problems associated with downtime of the host computer, but it introduced another known as data management. The same program might be loaded on ten different microcomputers with no communication among them. This problem is in the process of being solved by local area networks that connect microcomputers for better data management.中文译文：润滑和轴颈轴承1 介绍专用与支撑机器部件进行回转运动的原件可以被称为轴承。
轴承(机械类毕业设计外文翻译)
轴承寿命分析摘要自然界苛刻的工作条件会导致轴承的失效，但是如果遵循一些简单的规则，轴承正常运转的机会是能够被提高的。
在轴承的使用过程当中，过分的忽视会导致轴承的过热现象，也可能使轴承不能够再被使用，甚至完全的破坏。
但是一个被损坏的轴承，会留下它为什么被损坏的线索。
通过一些细致的观察工作，我们可以采取行动来避免轴承的再次失效。
关键词：轴承失效寿命1 .轴承失效的原因轴承失效有以下多种原因，然而轴承的寿命实验却是所有机械实验中最有意义的。
实验者必须控制实验过程以确保结果。
其他的失效模式在Tallian[19.2]中有详细论述。
下边几段就详细论述了可以影响寿命试验结果的几种失效模式。
23章中，从EHL的观点讨论了润滑条件对寿命试验结果的影响，同时还有其他的润滑条件会影响实验的结论，首先是润滑剂的接触面积，受到轴承的尺寸，转速，润滑剂的流动性等因素的影响，润滑剂在轴承表面形成的润滑层的厚度一般小于0.05~0.5um，大于这个薄层厚度的固体微粒会残留在接触面上，从而划伤润滑沟道和轴承的滚动面。
从而大大缩短轴承的耐用性。
关于这点Sayles和MacPherson 以及其他人都有详细的论证。
因此，为了确保实验结果我们必须选用合适等级的润滑剂。
润滑剂的选择由工况决定，实验时也如此。
如果工况选择的范围不确定，就必须考虑到接触面积对实验结果的影响。
23章中讨论了不同的接触面积对轴承失效寿命实验结果的影响。
潮气是影响润滑结果的另一个重要因素，长时间在水中和油中被腐蚀不但对外观质量有影响，还会影响到滚动表面的轴承寿命。
关于这点Fitch等人[19.7]有过论证。
而且，即使是仅有50~100PPM（百万分之一）的水汽含量也会产生有害影响，甚至产生表面看不出痕迹的腐蚀。
这是由于轴承的沟道和滚动面之间会产生氢脆现象，从23章中也可以看出在润滑实验中湿气是如此重要的一个因素。
因此在轴承寿命的试验结果中必须考虑到潮气的影响。
为了降低对寿命减少的影响，潮气的含量最多不能超过40PPM。
机械外文翻译中英文
机械外文翻译中英文附录附录1英文原文Rolling Contact BearingsThe concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to load; (b)stiffness,ie.deflections under load; (c) friction; (d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of a load rating will become important where loads are high,although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase fricitional drag. Wear is primarily associated with the introduction of contaminants,and sealing arrangements must be chosen with regard to the hostility of the environment.Because the high quality and low price of ball and roller bearing depends on quantity production,the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with steel which is through-hardened to about900HV,although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600HV. It is not surprising that,owing to the high stresses involved,a predominant form of failureshould be metal fatigue, and a good deal of work is based on accept values of life and it is general practice in bearing industry to define the load capacity of the bearing as that value below which 90 percent of a batch will exceed life of one million revolutions.Notwithstanding the fact that responsibility for basic design ofball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearingselection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to follow space for this.Where life is not the determining factor in design, it is usual to determine maximum loading by the amount to which a bearing will deflect under load. Thus the concept of "static load-carrying capacity" is understood to mean the load that can be applied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has been determined by practical experience as the load which whenapplied to a bearing results in a total deformation of 0.0025mm for a ball 25mm in diameter.The successful functioning of many bearings depends upon providing them with adequate protection against their environment, and in some circumstances the environment must be protected from lubricants or products of deterioration of the bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on basis of the appropriate bearing theory.Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.LathesLathes are widely used in industry to produce all kinds of machined parts. Some are general purpose machines, and others are used to perform highly specialized operations.Engine lathesEngine lathes, of course, are general-purpose machine used in production and maintenance shop all over the the world. Sized ranger from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes come equipped with attachments not commonly found in the ordinary shop, such as automatic shop for the carriage.Tracer or Duplicating LathesThe tracer or duplicating lathe is designed o produce irregularly shaped parts automatically. The basic operation of this lathe is as fallows. A template of either a flat or three-dimensional shape isplaced in a holder. A guide or pointer then moves along this shape andits movement controls that of the cutting tool. The duplication may include a square or tapered shoulder, grooves, tapers, and contours. Work such as motor shafts, spindles, pistons, rods, car axles, turbine shafts, and a variety of other objects can be turned using this type of lathe.Turret LathesWhen machining a complex workpiece on a general-purpose lathe, agreat deal of time is spent changing and adjusting the several toolsthat are needed to complete the work. One of the first adaptations ofthe engine lathe which made it suitable to mass production was the addition of multi-tool in place of the tailstock. Although most turrets have six stations, some have as many as eight.High-production turret lathes are very complicated machines with a wide variety of power accessories. The principal feature of all turret lathes, however, is that the tools can perform a consecutive serials of operations in proper sequence. Once the tools have been set and adjusted, little skill is require to run out duplicate parts.Automatic Screw MachineScrew machines are similar in construction to turret lathes, except that their heads are designed to hold and feed long bars of stock.Otherwise, their is little different between them. Both are designed for multiple tooling, and both have adaptations for identical work. Originally, the turret lathe was designed as a chucking lathe for machining small casting, forgings, and irregularly shaped workpieces.The first screw machines were designed to feed bar stock and wire used in making small screw parts. Today, however, the turret lathe is frequently used with a collect attachment, and the automatic screw machine can be equipped with a chuck to hold castings.The single-spindle automatic screw machine, as its name implies, machines work on only one bar of stock at a time. A bar 16 to 20 feet long is feed through the headstock spindle and is held firmly by a collect. The machining operations are done by cutting tools mounted on the cross slide. When the machine is in operation, the spindle and the stock are rotated at selected speeds for different operations. If required, rapid reversal of spindle direction is also possible.In the single-spindle automatic screw machine, a specific length of stock is automatically fed through the spindle to a machining area. At this point, the turret and cross slide move into position and automatically perform whatever operations are required. After the machined piece is cut off, stock is again fed into the machining area and the entire cycle is repeated.Multiple-spindle automatic screw machines have from four to eight spindles located around a spindle carrier. Long bars of stock, supported at the rear of the machine,pass though these hollow spindles and aregripped by collects. With the single spindle machines, the turret indexes around the spindle. When one tool on the turret is working, the others are not. With a multiple spindle machine, however, the spindle itself index. Thus the bars of stock are carried to thevarious end working and side working tools. Each tool operates in only one position, but tolls operate simultaneously. Therefore, four to eight workpieces can be machined at the same time.Vertical Turret LathesA vertical turret is basically a turret lathe that has been stood on its headstock end. It is designed to perform a variety of turning operations. It consists of a turret, a revolving table, and a side head with a square turret for holding additional tools. Operations performed by any of the tools mounted on the turret or side head can be controlled through the use of stops.Machining CentersMany of today's more sophisticated lathes are called machining centers since they are capable of performing, in addition to the normal turning operations, certain milling and drilling operations. Basically, a machining center can be thought of as being a combination turret lathe and milling machine. Additional features are sometimes included by the versatility of their machines.Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control(NC). Prior to the adventof NC, all machine tools were manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations in manufacturing technology:1. Electrical discharge machining.2. Laser cutting.3. Electron beam welding.Numerical control has also made machines tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide variety of parts, each involving anassortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tools and processes.Like so many advanced technologies, NC was born in the laboratories of the Masschusetts Institute of Technology. The concept of NC was developed in early 1950s with funding provided by the U.S.Air force. In its earliest stages, NC machines were able to make straight cuts efficiently and effectively.However,curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter is straight lines making up the steps, the smoother is the curve. Each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools(APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the further development of NC technology. The original NC systems were vastly different from those used today. The machines had hardwired logic circuits. This instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape.A tape reader was used to interpret the instructions written on the tapefor the machine. Together, all of this represented a giant step forwardin the control of machine tools. However, there were a number ofproblems with NC at this point in its development.A major problem wad the fragility of the punched paper tape medium.It was common for the paper tape containing the programmed instructionsto break or tear during a machining process. This problem wasexacerbated by the fact that each programmed instructions had to bereturn through the reader. If it was necessary to produce 100 copies ofa given part,it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could notwithstand the rigors of a shop floor environment and this kind ofrepeated use.This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions as a seriesof holes punched in the tape, the plastic tapecarried the instructions as a series of magnetic dots. The plastictape was much stronger than the paper taps, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossibleto change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it necessary tointerrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a realityand soon solved the problem of NC associated with punched paper and plastic tape.The development of a concept known as direct numericalcontrol(DNC)solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend o a host computer. When the lost computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.The development of the microprocessor allowed for the development of programmable logic controllers(PNC)and microcomputer. These two technologies allowed for the development of computer numericalcontrol(CNC). With CNC, each machine tool has a PLC or a microcomputer that serves the same purpose. This allows programs to be input and stored at each individual machine tool. It also allows programs to be developed off-line and download at the individual machine tool. CNC solved the problems associated with downtime of the host computer, butit introduced another known as data management. The same program mightbe loaded on ten different being solved by local area networks that connect microcomputer for better data management.CNC machine tool feed motion systemsCNC machine tool feed motion systems, especially to the outline of the control of movement into the system, must be addressed to the movement into the position and velocity at the same time the realization of two aspects of automatic control, as compared with the general machine tools, require more feed system high positioning accuracy and good dynamic response. A typical closed-loop control of CNC machine tool feed system, usually by comparing thelocation of amplification unit, drive unit, mechanical transmission components, such as feedback and testing of several parts. Here as mechanical gear-driven source refers to the movement of the rotary table into a linear motion of the entire mechanical transmission chain, including the deceleration device, turning the lead screw nut become mobile and vice-oriented components and so on. To ensure that the CNC machine tool feed drive system, precision, sensitivity and stability, the design of the mechanical parts of the general requirement is to eliminate the gap, reducing friction, reducing the movement of inertia to improve the transmission accuracy and stiffness. In addition, the feeding system load changes in the larger, demanding response characteristics, so for the stiffness, inertia matching the requirements are very high.Linear Roller GuidesIn order to meet these requirements, the use of CNC machine tools in general low-friction transmission vice, such as anti-friction sliding rail, rail rolling and hydrostatic guideways, ball screws, etc.; transmission components to ensure accuracy, the use of pre-rational, the form of a reasonable support to enhance the stiffness of transmission; deceleration than the best choice to improve the resolution of machine tools and systems converted to the driveshaft on the reduction of inertia; as far as possible the elimination of drive space and reduce dead-zone inverse error and improve displacement precision.Linear Roller Guides outstanding advantage is seamless, and can impose pre-compression. By the rail body, the slider, ball, cage, end caps and so on. Also known as linear rolling guide unit. Use a fixed guide body without moving parts, the slider fixed on the moving parts. When the slider moves along the rail body, ball and slider in the guide of the arc between the straight and through the rolling bed cover of Rolling Road, from the work load to non-work load, and then rolling back work load, constant circulation, so as to guide and move the slider between the rolling into a ball.附录2中文翻译滚动轴承对于球轴承和滚子轴承，一个机械设计人员应该考虑下面五个方面:(a)寿命与载荷关系;(b)刚度，也就是在载荷作用下的变形;(c)摩擦;(d)磨损;(e)噪声。
机械外文翻译---关于轴承和轴的相关知识
附录一Knowledge On The Bearings and ShaftThe bearings are fixed and reduce the load coefficient of friction in the process of mechanical transmission components. Can also say that when the other parts on the shaft relative motion, used to reduce the friction coefficient in the process of power transfer and fixed the mechanical parts to maintain the position of the shaft center. Bearings are important parts of modern machinery and equipment. Its main function is to support the mechanical rotating body to reduce the load coefficient of friction of the mechanical equipment in the transmission process. According to the different nature of friction of moving parts, bearings can be divided into two types of rolling bearings and plain bearings.Nano Lake, Italy, found a Roman vessel discovered early instance of ball bearings. The wooden ball bearings are used to support the rotating desktop. Ship construction in 40 BC. It is said that Leonardo da Vinci in the 1500 or so, a ball bearing through description. , There is a very important point is the ball collision, causing additional friction between the ball bearings of all kinds of immature factors. But can put the ball into a small cage to prevent this phenomenon. The 17th century, Galileo fixed ball ", or" cage ball "ball bearings did the earliest description. But then quite a long time, the bearings have been installed on the machine. The first patent on the ball channel the Carmarthen Philip Vaughan in 1794.In 1883, Friedrich Fischer proposed the idea of the use of suitable production machine grinding the same size, roundness accurate ball. This laid the foundation to create an independent bearing industry. In 1962, FAG the trademark has been modified and are still used today and become an integral part of the company in 1979.In 1895, Henry Timken designed the first tapered roller bearings, three years later obtained a patent and the establishment of the Timken Company.In 1907, SKF bearing factory Sven temperature Qwest designed the first modern self-aligning ball bearings.Study its role should be in terms of support, that the literal interpretation is used to bearing axis, but this is only part of its role in supporting its essence is to be able to bear the radial load. Can also be understood that it is used to a fixed axis. A fixed axis so that it can only achieverotation, and control of axial and radial movement. Motor without bearing the consequences is not work at all. Because the axis may be in any direction movement, the motor work requirements shaft only rotation. Impossible to realize the role of the drive, in theory, not only that, bearing also affect the transmission must be achieved in order to reduce this effect in the high speed shaft bearing lubrication, and some bearing lubrication, called pre-lubricated bearings, and the most of the bearing lubricant, the load at high speeds, due to the friction will not only increase energy consumption, even worse, is very easy to damage the bearing. Sliding friction into rolling friction is one-sided to say things because of the kind called plain bearings.Bearing the classification and described as follows:Equipped with a thin and long roller needle bearing (the length of the roller diameter of 3 to 10 times the diameter of generally not more than 5mm), therefore the radial structure is compact, its inner diameter and load capacity with other types of bearing the same minimum outside diameter, especially for supporting the results of radial installation dimensions restricted. needle bearing according to the use of different occasions, can be used without inner ring bearings or needle roller and cage assembly and bearing to match the journal surface directly as a bearing surface and shell holes, outer rolling surface in order to ensure the load capacity and running performance with a ring bearing the same shaft or shell holes on the raceway surface of the hardness, the machining accuracy and surface quality should be the bearing rings. use Combined needle roller bearings to the heart needle roller bearings and thrust bearing parts bearing units of the combination of its compact size, small, high precision rotation, can withstand high radial load to bear certain axial load. And the product structure in various forms, wide adaptability, easy to install. Combined needle roller bearings are widely used in machine tools, metallurgical machinery, textile machinery, printing machinery and other machinery and equipment, and make the mechanical system design is very compact and nimble.Aligning ball bearings Self-aligning ball bearings: two of the inner ring raceway and the raceway between the spherical outer ring, the assembly of the drum-shaped roller bearing. The outer ring raceway curvature center and bearing center line, and therefore have the same aligning and self-aligning ball bearings. Axis, the shell deflection occurs, you can automatically adjust to not increase the burden of bearing. Spherical roller bearings can bear radial load and axial load in two directions. Aligning ball bearing radial load capacity, suitable for a heavy impact loadconditions. The inner diameter is tapered bore bearings can be installed directly. Or use the adapter sleeve, remove the tube installed in the cylinder axis. Cage the use of steel stamping cage, forming polyamide-aligning ball bearings withstand heavy loads and impact loads, precision instruments, low noise motors, automobiles, motorcycles, metallurgy, mill, mining, petroleum, paper, cement, pressed sugar industry and the general machinery.Deep groove ball bearings imported bearings are mainly used for pure radial load, both radial and axial load. Only under pure radial load, the contact angle is zero. Performance of angular contact bearings, deep groove ball bearings with a larger radial clearance, and is subjected to high axial load. Deep groove ball bearings, the friction coefficient is small, the limit speed is also high, especially in a large high-speed operation of the axial load conditions, deep groove ball bearings Thrust ball bearings are more advantages. Deep groove ball bearings are the most representative of the rolling bearings, widely used. For high speed or high speed operation, and is very durable, without regular maintenance. The class has a small coefficient of friction, high limiting speed, simple structure, low manufacturing cost, easy to achieve high manufacturing precision. Size range and diversity, changes in the form used in precision instruments, low noise motors, automobiles, motorcycles and general machinery and other industries, is the machinery industry's most widely used type of bearings. The main radial load, and can withstand a certain amount of axial load deep groove ball bearings can be used for the transmission, instrumentation, motors, appliances, internal combustion engines, transportation vehicles, agricultural machinery, construction machinery, construction machinery and so on.Aligning roller bearing is a spherical outer ring between the two raceways of the inner ring raceway assembly with drum-shaped roller bearings. Aligning roller bearing with two rollers, mainly exposed to the diameter of a load, but also able to withstand the axial load in either direction. High radial load capacity, especially suitable for work overload or vibration loads, but can not afford the pure axial load. This kind of bearing outer ring raceway is spherical shape, aligning performance is good, can compensate concentricity error. Spherical roller bearings have two symmetrical spherical roller outer ring of a common spherical raceway, two bearing axis of inner ring tilt angle of the raceway, has a good aligning properties, when the axis force bearing when bending or install a different heart to continue its normal use, tune concentric with the bearing dimension series vary, generally allow aligning angle of 2.5 degrees, the type of loadbearing capacity, in addition to radial loads The outer bearings can withstand axial load of the two-way role, with good impact resistance, in general, self-aligning roller bearings allowed speed is low. Spherical roller bearings according to the section shape of the roller is divided into two different structures of the symmetrical spherical roller and non-symmetrical spherical roller, asymmetric self-aligning roller bearings are early products, mainly the host repair services, new design host rarely use symmetrical self-aligning roller bearings, the internal structure of the overall improvement of the design and parameters optimization, than with the early production of aligning roller bearings, able to withstand greater axial load, this bearing run lower temperatures, it can adapt to the requirements of high speed, according to whether the inner rib and cage can be divided into two kinds of C and CA, C-type bearing is characterized by the inner wall and the use of steel stamping frame, the CA-bearing characteristics for the inner ring on both sides have ribs machined solid cage in order to improve the lubrication, can provide users with the outer ring with a circular tank, and three hole Spherical roller bearings, set the code to the bearings / W33 can also supply according to the requirements of users with the inner hole of the aligning roller bearings, in order to facilitate customer handling and replacement of bearings, can also be provided within the hole with a taper aligning roller bearings, bearings, tapered bore, taper 1:12 after the set, code-named K, in order to adapt to specific user requirements can also be provided within the taper bearings of 1:30, followed by the set, code-named K30 hole with The taper of the bearing can be used locknut bearing mounted on the conical journal, but also can make use of the adapter sleeve or withdrawal sleeve bearings installed in the cylindrical journal.Combination of bearing: a bearing formed by the combination of bearing structure in the above-mentioned two or more of rolling bearings. Such as needle roller and cylindrical roller thrust bearings, needle roller and thrust ball bearings, needle roller and angular contact ball bearings, etc..Bearing life: under certain loads, the bearings in the number of revolutions or hours before pitting experienced, known as the bearing life.The life of rolling bearings of the number of revolutions (or number of hours worked under a certain speed) is defined: In this life within the bearing, any bearing ring or rolling body on the initial fatigue damage (spalling or defect). But both in the laboratory tests or in actual use, can clearly see the appearance of the same bearing in the same working conditions, to differ materiallyfrom actual life. In addition to the bearing of several different definitions of "life", one of the so-called "working life", it means that the actual life of a bearing can be achieved before the damage from the wear and tear, damage is usually not caused by fatigue, but caused by wear and tear, corrosion, seal damage.Due to differences in manufacturing precision, material uniformity, even if the same material, bearing the same batch of the same size, in the same working conditions, their longevity is not the same. In terms of statistical life is 1 unit relative life expectancy of up to four units, the shortest was 0.1 to 0.2 units, the ratio of the longest and shortest life of 20 to 40 times.The installation of bearings:Bearing installation, good or bad, will affect the accuracy, bearing life and performance. , The installation of the bearing, in accordance with the operating standards include the following items, including the bearing installation.①cleaning bearings and related parts have been greased bearings and bilateral withseals or dust cover, no need to clean before the installation of the ring bearing.② Check the size and finishing conditions of the relevant parts of the③installation method bearing installation should be based on the nature of the bearing structure, size, and bearing components with pressure should be directly added to a tight fit to the ferrule end surface, may not pass the pressure of the rolling element bearing installation generally use the following method: a press-fit bearing inner ring and shaft so tight fit, the outer ring and the bearing hole is loose with the available presses will be bearing the first pressure mounted on the shaft and the shaft together with the bearing with load bearing hole press-fit bearing inner ring side surface, pad assembly sleeve of a soft metal material (copper or mild steel), the assembly casing diameter should be slightly larger than the journal diameter, the diameter of the outer diameter than the bearing inner ring ribs slightly smaller, in order to avoid pressure in the cage. The bearing outer ring and the bearing hole is a tight fit, the inner ring and the shaft is loose with the bearing first pressed into the bearing hole, this time the assembly casing outside diameter should be slightly smaller than the diameter of the bore. If the bearing ring and shaft and housing bore are a tight fit to install the indoor ring and outer ring to be pressed into the shaft and housing bore, the assembly structure of the casing should be able to charge tight end face of the bearing inner and outer rings. (b) heating with heated bearings or bearing, the use of thermal expansionwill be a tight fit to change the installation method for a loose fit.④ bearing installation inspection⑤lubricant added to the installation of high-speed precision angular contact ball bearings, mainly for the load lighter, high-speed rotating occasions, the requirement of bearing high-precision, high speed, low temperature rise Low vibration and service life of high-speed precision angular contact ball bearings. Often for high-speed electric spindle bearing installed in pairs, the key component parts of the inner surface of the grinding machine of high speed electric spindle. The main technical indicators: 1. Bearing accuracy specifications: more than GB/307.1-94 the P4 level precision high-speed performance: dmN value of 1.3 ~ 1.8x 106 / min 3. Life (average):> 1500 hLife of high-speed precision angular contact ball bearings have a great relationship with the installation, you should note the following: ①The bearings shall be installed in a clean, clean room, bearing carefully matching, bearing spacers to go through grinding, maintaining the premise of high-inside and outside the ring spacers, spacer parallelism should be controlled in 1um following; ②The bearings prior to installation should be clean, cleaning inner slopes upward, should be flexible and feel no sense of stagnation, dried and put into the specified amount of grease, in the case of oil mist lubrication should be placed in a small amount of oil mist oil; ③bearing installation should be used specialized tools, even by force, strictly prohibited beating; ④The bearings shall be stored in clean air, corrosive gases, relative humidity of not more than 65 % long-term storage should be periodically rust-proof.Tapered roller bearings, water pump bearing installation:①the installation of bearings: bearing must be installed in a dry, clean environment conditions. Before installation, carefully check the mating surface of the shaft and shell, the face of the convex shoulder trench and connection quality of surface processing. All match the connected surface must be carefully cleaned and remove the burrs, casting raw surface must be in addition to net sand. Bearing installation should be preceded by cleaning with gasoline or kerosene, clean and dry before use, and to ensure good lubrication, bearings are commonly used grease lubrication, oil lubrication can be used. With grease lubrication should be used free of impurities, anti-oxidation, rust and extreme pressure performance superior grease. The grease filling is 30% to 60% of the bearings and the bearing capacity of the container, not too much. Withsealing structure of the double row tapered roller bearings and pump shaft bearing filled a good grease, users can directly use, not for cleaning. Bearing installation, you must exert equal pressure on the circumference of the ferrule end face pressed into the ring not want first-class tools to tap the bearing face, so as not to damage the bearing. Small amount of interference with the sleeve at room temperature, press and hold the bearing ring face hammer to beat the sleeve through the sleeve rings evenly pressed into. If large quantities of installation can be a hydraulic press.②bearing removal: Remove the bearing intend to continue to use, you should use the appropriate removal tool. The demolition of the interference fit of the ring, only to increase the tension in the ring, never to allow demolition of the rolling elements, or the rolling element and raceway will be crushed.③bearing use of the environment: the use of location and conditions of use and environmental conditions to select the specifications of size, accuracy, and with the right bearing is the premise to ensure that the bearing life and reliability. Parts: tapered roller bearings are suitable to withstand the radial load mainly radial and axial joint load, usually paired to two sets of bearings used primarily in the car's front and rear wheel hub, active bevel gear, differential, reducer and transmission parts. Allowable speed: correctly installed, well-oiled environment, allowing the bearing limit speed of 0.3 to 0.5 times. Under normal circumstances, the limit of 0.2 times the speed of the most suitable. Allow the angle of inclination: tapered roller bearings are generally not allowed axis of the relative shell hole tilt, where tilt maximum of not more than 2 '. Allow the temperature: under the normal load, the lubricant has high temperature resistance, and adequate lubrication conditions, the general bearing allows to work in -30 ° C to 150 ° C ambient temperature.Axis function and type:Axis is one of the important parts in the machine, used to support the rotating parts of machinery.Depending on the load bearing axis can be divided into the shaft, drive shaft and spindle three kinds. Shaft only transfer torque to withstand bending moments, such as the gear reducer shaft; drive shaft transmitting torque only not withstand the bending moment or bending moment is small. Such as automotive drive shaft; spindle is exposed only to the moment rather than transmit torque, such as the axis of the rail vehicle, the front axle of the bicycle.The shape of the shaft axis can be divided into: straight axle, crankshaft and flexible wire axis. Crankshaft is commonly used in reciprocating machinery. The flexible wire shaft wire layers close together by layers of flexible torque and rotational movement spread to any location commonly used in vibrators and other devices. This chapter only study the direct axis.Shaft design, manufacturing process according to job requirements and to consider other factors, the appropriate choice of materials, structural design, through strength and stiffness, set the axis of the structure shape and size, if necessary, consider the vibration stability.Axis of the commonly used materials:The axis of the material is often used carbon steel and alloy steel.Carbon steel bearing 35,45,50 high-quality carbon structural steel has higher mechanical properties, more applications, of which the most widely used steel 45. In order to improve its mechanical properties, normalizing or quenching and tempering treatment. Unimportant, or by a smaller force axis, can be used such as Q235, Q275 carbon structural steel.Alloy steel alloy steel has higher mechanical properties, but the price is more expensive, used for special requirements of the shaft. For example: the sliding bearings of high-speed shaft, commonly used in 20Cr, 20CrMnTi low-carbon alloy structural steel after carburizing can improve the wear resistance of the journal; generator rotor shaft in the high temperature, high-speed and overload conditions. must have good high temperature mechanical properties, often to adopt 40CrNi, 38CrMoAlA alloy structural steel. It is worth noting: the type and heat treatment of steel, its elastic modulus is very small. For use of alloy steel or heat treatment to improve the shaft stiffness is no practical results. In addition, the alloy steel higher sensitivity to stress concentration, alloy steel shaft design, more should be structured to avoid or reduce the stress concentration and reduce the surface roughness.Axis rough general round bar or forgings, and sometimes can be cast or ductile iron. For example, made of nodular cast iron crankshaft, camshaft, low cost, better vibration absorption, low sensitivity to stress concentration, good strength, etc..Axis of structural design:The axis of the structure design is to make each part of the axis has a reasonable shape and size. Its main requirements are: 1) axis should be easy processing. Parts of the shaft to be easy disassembly (manufacture and installation requirements); 2) axis and the shaft parts have accurateposition (location); 3) parts to firmly and reliably and relatively fixed (fixed); 4) to improve the force situation, reducing the stress concentration.①The manufacturing installation requirementsIn order to facilitate the assembly and disassembly of the shaft parts, often the shaft made of the ladder. Split the box in the shaft, its diameter from the shaft end and gradually increases toward the middle. As shown above, can turn the gear, the sleeve, the left end bearings, bearing caps and pulley from the axis of the left end assembly and disassembly, and another from the right end of the assembly and disassembly of rolling bearings. Shaft parts is easy to install, should chamfer of the shaft end and the end of the shaft section.Axis grinding shaft section should wheel the more process slots; car threaded shaft section should be undercut.Meet the requirements of the case, the axis of the shape and size should be simple in order to facilitate processing.②The axis positioning of partsLadder shaft cross-section changes a place called the shaft shoulder, since the axial positioning of the role. Shaft shoulder makes gear positioned on the shaft; shaft shoulder pulley positioning; shaft shoulder to the right end of the rolling bearing positioning.Some parts rely on a set of simple positioning, such as above the left end of rolling bearings.③The axis parts of the fixedAxial fixation of the shaft parts, often with the shaft shoulder, sleeve, nut or shaft end of the retaining ring (also known as the plate) and other forms. Gear to achieve the axial two-way fixed. Gear by the axial force, right through the shaft shoulder, by the axis and shoulders in the rolling bearing inner ring; left sleeve top in the rolling bearing inner ring. Can not use the sleeve or sleeves too long, we can use the round nut to be fixed. Pulley axial fixed retaining ring depend on the shaft shoulder and the shaft end.Axis intensity calculated as follows:Axis intensity shall be calculated according to the shaft bearing, using the appropriate method of calculation. The common axis strength calculation method has the following two:① Press the torsional strength calculationThis method applies only to withstand the torque of the drive shaft of accurate calculation, iswell received by the bending moment and torque axis approximate calculation can also be used. Circular section shaft transmitting torque only, the strength condition.Withstand both pass to turn short axis of the bending moment can also be used on the preliminary estimate of the diameter of the design formula:In addition, the empirical formula can be used to estimate the diameter of the shaft. For example, in the general reducer, high-speed input shaft diameter according to its associated motor shaft diameter D estimates, d = (0.8 ~ 1. 2) D; all levels of low-speed shaft of the gear center distance on the shaft diameter according to the same level a estimates, d = (0.3 0.4) a.② According to the synthetic strength of the bending and torsionSingle-stage cylindrical gear reducer design sketches, each symbol indicates the length of the Dimensions. Obviously, when the parts laid out on the sketch, the role of location of the external load and support reaction force can be determined. Thus can be used for mechanical analysis of the shaft and draw the bending moment diagram and torque diagram. Then you can press the synthetic strength of the bending and torsion shaft diameter.For the cross-section of the keyway should be calculated shaft diameter increased by about 4%. Calculated shaft diameter greater than the shaft diameter of preliminary estimates of the structural design, that the strength of the chart axis is not enough, you must modify the structural design; calculated shaft diameter less than the estimates of the structural design of shaft diameter, and the difference is not very generally subject to the structural design of the shaft diameter.For general-purpose shaft designed by the above method can. Important axis, yet further strength check (such as the safety factor method), the calculation method available at the reference.Shaft stiffness calculated as follows:Axis by the bending moment will produce a bending torque role will have the torsional deformation. If the shaft stiffness is not enough, it will affect the normal work of the axis. For example, the deflection of the rotor shaft is too large, will change the rotor and stator gap and affect the performance of the motor. Another example is the rigidity of the machine spindle is enough, it will affect the machining accuracy. Therefore, in order so that the axis is not enough stiffness and failure, must be designed to limit their working conditions under the shaft deformationAxis of the concept of critical speed:Uneven due to structural asymmetries of the rotary parts, materials, processing errors and other reasons, to make the rotation center of gravity is precisely located in the geometric axis, it is almost impossible. In fact, the center of gravity and the geometric axis generally total a slight eccentricity, and thus the centrifugal force generated when rotating the axis by the interference of cyclical loading.Axis suffered external frequency axis since the vibration frequency of the same operation will be unstable vibration occurs, a phenomenon known as the resonance of the shaft. Resonance when the shaft speed is called the critical speed. If the shaft speed is stuck near the critical speed, the axis of deformation increases rapidly, as well as the axis, the extent of the damage or even the whole machine. Therefore, the important, especially high-speed axis to calculate the critical speed, and shaft speed n to avoid the critical speed nc.The shaft critical speed, the lowest one called the first critical speed, the remaining second, third ......Speed is below a first critical speed axis is called the rigid shaft; more than the first critical speed axis is called the flexible shaft.Slender axis machining process characteristics:(1) slender shaft turning the process characteristicsSlender shaft rigidity is poor, turning fashion folder properly, it is easy because of the role of cutting force and gravity bending deformation,Vibration, thus affecting the machining accuracy and surface roughness.The slender shaft of the thermal diffusivity of poor performance, the effect of cutting heat, will produce quite a large linear expansion. If the two ends of the shaft to a fixed support, the workpiece due to the elongation of the top bend.The longer axis, a walk the knife for a long time, tool wear, thus affecting the geometry of the precision of the parts.Car slender shaft supporting the workpiece with the tool holder, the two supporting block inappropriate parts pressure will affect the machining accuracy. If the pressure is too small or do not touch, it does not work, you can not improve the stiffness of the parts; if the pressure is too large, the parts are pressed to the lathe tool, the cutting depth increases, the car out of the diameter is small, continue to move with the turret bearing block support in the small-diameter cylindrical。
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。
机械类英语论文翻译.doc
机械类英语论文翻译.doc轴承内径 bearing bore diameter轴承寿命 bearing life轴承套圈 bearing ring轴承外径 bearing outside diameter轴颈 journal轴瓦、轴承衬 bearing bush轴端挡圈 shaft end ring轴环 shaft collar轴肩 shaft shoulder轴角 shaft angle轴向 axial direction轴向齿廓 axial tooth profile轴向当量动载荷 dynamic equivalent axial load轴向当量静载荷 static equivalent axial load轴向基本额定动载荷 basic dynamic axial load rating轴向基本额定静载荷 basic static axial load rating 轴向接触轴承 axial contact bearing轴向平面 axial plane轴向游隙 axial internal clearance轴向载荷 axial load轴向载荷系数 axial load factor轴向分力 axial thrust load主动件 driving link主动齿轮 driving gear主动带轮 driving pulley转动导杆机构 whitworth mechanism转动副 revolute (turning) pair转速 swiveling speed rotating speed转动关节 revolute joint转轴 revolving shaft转子 rotor转子平衡 balance of rotor装配条件 assembly condition锥齿轮 bevel gear锥顶 common apex of cone锥距 cone distance锥轮 bevel pulley; bevel wheel锥齿轮的当量直齿轮 equivalent spur gear of the bevel gear 锥面包络圆柱蜗杆 milled helicoids worm准双曲面齿轮 hypoid gear子程序 subroutine子机构 sub-mechanism自动化 automation自锁 self-locking自锁条件 condition of self-locking自由度 degree of freedom, mobility。
轴类毕业设计英文翻译、外文文献翻译
ShaftSolid shafts. As a machine component a shaft is commonly a cylindrical bar that supports and rotates with devices for receiving and delivering rotary motion and torque .The crankshaft of a reciprocating engine receive its rotary motion from each of the cranks, via the pistons and connecting roads (the slider-crank mechanisms), and delivers it by means of couplings, gears, chains or belts to the transmission, camshaft, pumps, and other devices. The camshafts, driven by a gear or chain from the crankshaft, has only one receiver or input, but each cam on the shaft delivers rotary motion to the valve-actuating mechanisms.An axle is usually defined as a stationary cylindrical member on which wheels and pulleys can rotate, but the rotating shafts that drive the rear wheels of an automobile are also called axles, no doubt a carryover from horse-and-buggy days. It is common practice to speak short shafts on machines as spindles, especially tool-carrying or work-carrying shafts on machine tools.In the days when all machines in a shop were driven by one large electric motor or prime mover, it was necessary to have long line shafts running length of the shop and supplying power, by belt, to shorter couter shafts, jack shafts, or head shafts. These lineshafts were assembled form separate lengths of shafting clampled together by rigid couplings. Although it is usually more convenient to drive each machine with a separate electric motor, and the present-day trend is in this direction, there are still some oil engine receives its rotary motion from each of the cranks, via the pistons and connecting roads (the slider-crank mechanisms) , and delivers it by means of couplings, gears, chains or belts to the transmission, camshaft, pumps, and other devices. The camshafts, driven by a gear or chain from the crankshaft, has only one receiver or input, but each cam on the shaft delivers rotary motion to the valve-actuating mechanisms.An axle is usually defined as a stationary cylindrical member on which wheels and pulleys can rotate, but the rotating shafts that drive the rear wheels of an automobile are also called axles, no doubt a carryover from horse-and-buggy days. It is common practice to speak short shafts on machines as spindles, especially tool-carrying or work-carrying shafts on machine tools.In the days when all machines in a shop were driven by one large electric motor or prime mover, it was necessary to have long line shafts running length of the shop and supplying power, by belt, to shorter coutershafts, jackshafts, or headshafts. These line shafts were assembled form separatelengths of shafting clampled together by rigid couplings. Although it is usually more convenient to drive each machine with a separate electric motor, and the present-day trend is in this direction, there are still some situation in which a group drive is more economical.A single-throw crankshaft that could be used in a single-cylinder reciprocating engine or pump is shown in Figure 21. The journals A andB rotate in the main bearings,C is the crankpin that fits in a bearing on the end of the connecting rod and moves on a circle of radius R about the main bearings, whileD andE are the cheeks or webs.The throw R is one half the stroks of the piston, which is connected, by the wrist pin, to the other end of the connecting rod and guided so as to move on a straight path passing throw the axis XX. On a multiple-cylinder engine the crankshaft has multiple throws---eight for a straight eight and for a V-8---arranged in a suitable angular relationship.Stress and strains. In operation, shafts are subjected to a shearing stress, whose magnitude depends on the torque and the dimensions of the cross section. This stress is a measure of resistance that the shaft material offers to the applied torque. All shafts that transmit a torque are subjected to torsional shearing stresses.In addition to the shearing stresses, twisted shafts are also subjected to shearing distortions. The distorted state is usually defined by the angle of twist per unit length; i.e., the retation of one cross section of a shaft relative to another cross section at a unit distance from it.Shafts that carry gears and pulleys are bent as well as twisted, and the magniude of the bending stresses, which are tensile on the convex side of the bend and compressive on the concave side, will depend on the load, the distance between the bearings of the shaft cross section.The combination of bending and twisting produces a state of stress in the shaft that is more complex than the state of pure shears produced by torsion alone or the state of tension-compression produced by bending alone.To the designer of shaft it is important to know if the shaft is likely to fail because of an excessive normal stress. If a piece of chalk is twisted, it will invariably rupture on a plane at about 45 degrees to the axis. This is because the maximum tensile stresses act on this plane, and chalk is weak in tension. Steel shafting is usually designed so that the maximum shearing stress produced by bending and torsion is less than a specified maximum.Shafts with circular cross sections are easier to produce in the steel mill, easier to machine, andeasier to support in bearings than shafts with other cross section; there is seldom any need for using noncircular shapes. In addition, the strength and stiffness, both in bending and torsion, are more easily calculated for circular shafts. Lastly, for a given amount of materials the circular shafts has the smallest maximum shearing stress for a given torque, and the highest torsional rigidity.The shearing in a circular shaft is highest at the surface and drops off to zero at the axis. This means that most of the torque is carried by the material on and near the surface.Critical speeds. In the same way that a violin string vibrates when stroked with a bow, a cylindrical shaft suspended between two bearings has a natural frequency of lateral vibration. If the speed of revolution of the shaft coincides with the natural frequency, the shaft experience a whirling critical speed and become noisy. These speeds are more likely to occur with long, flexible shafts than with short, stiff ones. The natural frequency of a shaft can be raised by increasing its stiffness.If a slender rod is fixed to the ceiling ta one end and supports a heavy disk at the other end, the disk will oscillate back and forth around the rod axis like a torsion pendulum if given an initial twist and let go. The frequency of the oscillations will depend on the torsional stiffness of the rod and the weight of the disk; the stiffer the rod and the lighter the disk the higher the frequency. Similar torsional oscillations can occur in the crankshafts of reciprocating engines, particularly those with many crank throws and a heavy flywheel. Each crank throw and part of the associated connecting rod acts like a small flywheel, and for the crankshaft as a whole, there are a number of ways or modes in which there small flywheels can oscillate back and forth around the shaft axis in opposition to one another and to the main flywheel. For each of these modes there corresponds a natural frequency of oscillation.When the engine is operating the torques delivered to the crankshaft by the connecting rods fluctuate, and if the crankshaft speed is such that these fluctuating impulses are delivered at a speed corresponding to one of the natural torsional frequencies of the shaft, torsional oscillations will be superimposed on the rotary motion of the shafts. Such speed are known as torsional critical speeds, and they can cause shaft failures. A number of devices to control the oscillations of crankshafts have been invented.Flexible shafts. A flexible shaft consists of a number of superimposed tightly wound right-and left-hand layers of helically wound wires wrapped about a single center wire or mandrel. The shaft is connected to source of power and the driven member by special fittings attached to the end of theshaft. Flexible easings of metallic or nonmetallic materials, which guide and protect the shaft and retain the lubricant, are also available. Compared with solid shafts, flexible shafts can be bent to much smaller radii without being overstressed.For transmitting power around corners and for considerable distances flexible shafts are usually cheaper and more convenient than belts, chains, or gears. Most speedometers on automobiles are driven by flexible shafts running from the transmission to the dashboard. When a valve, a switch, or other control devices is in a hard-to-reach location, it can be operated by a flexible shaft from a more convenient position. For portable tools such as sanders, grinders, and drilling machines, flexible shafts are practically indispensable.KEY, SPLINES AND PINSKeys, splines, and pins. When power is being transmitted from a machine member such as a coupling, a gear, a flywheel, or a pulley to the shaft on which it is mounted, means must be provided for preventing relative motion between the shaft and the member. On helical and bevel gears, relative movement along the shaft caused by the thrust(axial) loads is prevented by a step in the shaft or by having the gear contact the bearing directly or through a tubular spacer. When axial loads are incidental and of small magnitude, the members are kept from sliding along the shaft by means of a set screw. The primary purpose of keys, splines, and pins is to prevent relative rotary movement.A commonly used type of key has a square cross section and is sunk half in the shaft and half in the hub of the other member. If the key is made of steel(which is commonly the case)of the same strength as the shaft and has a width and depth equal to one fourth of the shaft diameter(this proportion is closely approximated in practice) then it will have the same torque capacity as the solid shaft if its length is 1.57 times that of the shaft diameter. Another common type of key has a rectangular cross section with a depth to width ratio of 0.75. Both of these keys may either be straight or tapered in depth. The straight keys fit snugly on the sides of the key ways only, the tapered keys on all sides. Gib-head keys are tapered keys with a projection on one end to facilitate removal.Woodruff keys are widely used on machine tools and motor vehicles. The key is a segment of adisk and fits in a keyway in the shaft that is with a special milling cutter. Though the extra depth of these keys weakens the shaft considerably, it prevents any tendency of the key to rotate or move axially. Woodruff keys are particularly suitable for tapering shaft ends.Because they weaken the shafts less, keys with straight or tapered circular cross sections are sometimes used in place of square and rectangular keys, but the keyways, half in the shaft and half in the shaft and half in the hub, must be cut with a drill after assembly,and interchangeability of parts is practically impossible. When a large gear blank is made by shrinking a high-strength rim on a cheaper cast center, circular keys, snugly fitted, are frequently used to ensure a permanent connection.Splines are permanent keys integral with the shaft, fitting in keyways cut in the hub. The dimensions of splined fittings are standardized for both permanent (press) fits and sliding fits. The teeth have either straight or involute profiles;the latter are stronger, more easily measured, and have a self-centring action when twisted.Tapered circular pins can be used to restrain shaft-mounted members from both axial and rotary movement. The pin fits snugly in a reamed tapered hole that is perpendicular to the shaft surface. A number of straight pins that grip by deforming elastically or plastically when driven into straight holes are commercially available.All the keys and pins that have been described are standard driving devices. In some cases they inadequate, and unorthodox means must be employed. For driving small gear in which there is no room between the bore and the roots of the teeth for a longitudinal keyway, a transverse radial slot on the end of the gear can be made to fit a radial protuberance on the shaft. For transmitting moderate loads, a cheaper and effective connection can be made by forming a series of longitudinal serrations on the shaft with a knurling tool and pressing the shaft into the hole in the driven member, it will cut grooves in the hole and provide, in effect, a press-fitted splined connection. Press and shrink fits are also used, and they can provide surprisingly firm connections, but the dimensions of the connected member must be closely controlled.轴实心轴轴作为机械零件通常是一根圆柱形杆，用来支撑部件并随部件一起转动以接受和传递转动和扭矩。
机械外文翻译中英文
机械外文翻译中英文附录1英文原文Rolling Contact BearingsThe concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to load; (b) stiffness,ie.deflections under load; (c) friction; (d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of a load rating will become important where loads are high,although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase fricitional drag. Wear is primarily associated with the introduction of contaminants,and sealing arrangements must be chosen with regard to the hostility of the environment.Because the high quality and low price of ball and roller bearing depends on quantity production,the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with steel which is through-hardened to about 900HV,although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600HV. It is not surprising that,owing to the high stresses involved,a predominant form of failure should be metal fatigue, and a good deal of work is based on accept values of life and it is general practice in bearing industry to define the load capacity of the bearing as that value below which 90 percent of a batch will exceed life of one million revolutions.Notwithstanding the fact that responsibility for basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to follow space for this.Where life is not the determining factor in design, it is usual to determine maximum loadingby the amount to which a bearing will deflect under load. Thus the concept of "static load-carrying capacity" is understood to mean the load that can be applied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has been determined by practical experience as the load which when applied to a bearing results in a total deformation of 0.0025mm for a ball 25mm in diameter.The successful functioning of many bearings depends upon providing them with adequate protection against their environment, and in some circumstances the environment must be protected from lubricants or products of deterioration of the bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on basis of the appropriate bearing theory.Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.LathesLathes are widely used in industry to produce all kinds of machined parts. Some are general purpose machines, and others are used to perform highly specialized operations.Engine lathesEngine lathes, of course, are general-purpose machine used in production and maintenance shop all over the the world. Sized ranger from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes come equipped with attachments not commonly found in the ordinary shop, such as automatic shop for the carriage.Tracer or Duplicating LathesThe tracer or duplicating lathe is designed o produce irregularly shaped parts automatically. The basic operation of this lathe is as fallows. A template of either a flat or three-dimensional shape is placed in a holder. A guide or pointer then moves along this shape and its movement controls that of the cutting tool. The duplication may include a square or tapered shoulder, grooves, tapers, and contours. Work such as motor shafts, spindles, pistons, rods, car axles, turbine shafts, and a variety of other objects can be turned using this type of lathe.Turret LathesWhen machining a complex workpiece on a general-purpose lathe, a great deal of time isspent changing and adjusting the several tools that are needed to complete the work. One of the first adaptations of the engine lathe which made it suitable to mass production was the addition of multi-tool in place of the tailstock. Although most turrets have six stations, some have as many as eight.High-production turret lathes are very complicated machines with a wide variety of power accessories. The principal feature of all turret lathes, however, is that the tools can perform a consecutive serials of operations in proper sequence. Once the tools have been set and adjusted, little skill is require to run out duplicate parts.Automatic Screw MachineScrew machines are similar in construction to turret lathes, except that their heads are designed to hold and feed long bars of stock. Otherwise, their is little different between them. Both are designed for multiple tooling, and both have adaptations for identical work. Originally, the turret lathe was designed as a chucking lathe for machining small casting, forgings, and irregularly shaped workpieces.The first screw machines were designed to feed bar stock and wire used in making small screw parts. Today, however, the turret lathe is frequently used with a collect attachment, and the automatic screw machine can be equipped with a chuck to hold castings.The single-spindle automatic screw machine, as its name implies, machines work on only one bar of stock at a time. A bar 16 to 20 feet long is feed through the headstock spindle and is held firmly by a collect. The machining operations are done by cutting tools mounted on the cross slide. When the machine is in operation, the spindle and the stock are rotated at selected speeds for different operations. If required, rapid reversal of spindle direction is also possible.In the single-spindle automatic screw machine, a specific length of stock is automatically fed through the spindle to a machining area. At this point, the turret and cross slide move into position and automatically perform whatever operations are required. After the machined piece is cut off, stock is again fed into the machining area and the entire cycle is repeated.Multiple-spindle automatic screw machines have from four to eight spindles located around a spindle carrier. Long bars of stock, supported at the rear of the machine,pass though these hollow spindles and are gripped by collects. With the single spindle machines, the turret indexes around the spindle. When one tool on the turret is working, the others are not. With a multiple spindle machine, however, the spindle itself index. Thus the bars of stock are carried to the various end working and side working tools. Each tool operates in only one position, but tollsoperate simultaneously. Therefore, four to eight workpieces can be machined at the same time.Vertical Turret LathesA vertical turret is basically a turret lathe that has been stood on its headstock end. It is designed to perform a variety of turning operations. It consists of a turret, a revolving table, and a side head with a square turret for holding additional tools. Operations performed by any of the tools mounted on the turret or side head can be controlled through the use of stops.Machining CentersMany of today's more sophisticated lathes are called machining centers since they are capable of performing, in addition to the normal turning operations, certain milling and drilling operations. Basically, a machining center can be thought of as being a combination turret lathe and milling machine. Additional features are sometimes included by the versatility of their machines.Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control(NC). Prior to the advent of NC, all machine tools were manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent than limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first major step away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations in manufacturing technology:1.Electrical discharge machining.ser cutting.3. Electron beam welding.Numerical control has also made machines tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide variety of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tools and processes.Like so many advanced technologies, NC was born in the laboratories of the Masschusetts Institute of Technology. The concept of NC was developed in early 1950s with funding provided by the U.S.Air force. In its earliest stages, NC machines were able to make straight cuts efficiently and effectively.However,curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter is straight lines making up the steps, the smoother is the curve. Each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools(APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the further development of NC technology. The original NC systems were vastly different from those used today. The machines had hardwired logic circuits. This instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. A tape reader was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.A major problem wad the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each programmed instructions had to be return through the reader. If it was necessary to produce 100 copies of a given part,it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than thepaper taps, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it necessary to interrupt machining operations and make a new tape. It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problem of NC associated with punched paper and plastic tape.The development of a concept known as direct numerical control(DNC)solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend o a host computer. When the lost computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.The development of the microprocessor allowed for the development of programmable logic controllers(PNC)and microcomputer. These two technologies allowed for the development of computer numerical control(CNC). With CNC, each machine tool has a PLC or a microcomputer that serves the same purpose. This allows programs to be input and stored at each individual machine tool. It also allows programs to be developed off-line and download at the individual machine tool. CNC solved the problems associated with downtime of the host computer, but it introduced another known as data management. The same program might be loaded on ten different being solved by local area networks that connect microcomputer for better data management.CNC machine tool feed motion systems CNC machine tool feed motion systems, especially to the outline of the control of movement into the system, must be addressed to the movement into the position and velocity at the same time the realization of two aspects of automatic control, as compared with the general machine tools, require more feed system high positioning accuracy and good dynamic response.A typical closed-loop control of CNC machine tool feed system, usually by comparing the location of amplification unit, drive unit, mechanical transmission components, such as feedbackand testing of several parts. Here as mechanical gear-driven source refers to the movement of the rotary table into a linear motion of the entire mechanical transmission chain, including the deceleration device, turning the lead screw nut become mobile and vice-oriented components and so on. To ensure that the CNC machine tool feed drive system, precision, sensitivity and stability, the design of the mechanical parts of the general requirement is to eliminate the gap, reducing friction, reducing the movement of inertia to improve the transmission accuracy and stiffness. In addition, the feeding system load changes in the larger, demanding response characteristics, so for the stiffness, inertia matching the requirements are very high.Linear Roller GuidesIn order to meet these requirements, the use of CNC machine tools in general low-friction transmission vice, such as anti-friction sliding rail, rail rolling and hydrostatic guideways, ball screws, etc.; transmission components to ensure accuracy, the use of pre-rational, the form of a reasonable support to enhance the stiffness of transmission; deceleration than the best choice to improve the resolution of machine tools and systems converted to the driveshaft on the reduction of inertia; as far as possible the elimination of drive space and reduce dead-zone inverse error and improve displacement precision.Linear Roller Guides outstanding advantage is seamless, and can impose pre-compression. By the rail body, the slider, ball, cage, end caps and so on. Also known as linear rolling guide unit. Use a fixed guide body without moving parts, the slider fixed on the moving parts. When the slider moves along the rail body, ball and slider in the guide of the arc between the straight and through the rolling bed cover of Rolling Road, from the work load to non-work load, and then rolling back work load, constant circulation, so as to guide and move the slider between the rolling into a ball.附录2中文翻译滚动轴承关于球轴承和滚子轴承，一个机械设计人员应该考虑下面五个方面：（a)寿命与载荷关系；（b）刚度，也确实是在载荷作用下的变形；（c）摩擦；（d）磨损；（e）噪声。
轴承论文中英文资料外文翻译文献
中英文资料外文翻译文献EXTENDING BEARING LIFEAbstract：Nature works hard to destroy bearings, but their chances of survival can be improved by following a few simple guidelines. Extreme neglect in a bearing leads to overheating and possibly seizure or, at worst, an explosion. But even a failed bearing leaves clues as to what went wrong. After a little detective work, action can be taken to avoid a repeat performance.Keywords: bearings failures lifeBearings fail for a number of reasons，but the most common are misapplication，contamination，improper lubricant，shipping or handling damage，and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrong．However，while a postmortem yields good information，it is better to avoid the process altogether by specifying the bearing correctly in The first place．To do this，it is useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing.Equally critical is a study of requirements for noise, torque, and runout, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job.1 Why bearings failAbout 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environment．Fortunately, a bearing failure caused by environment or handling contamination is preventable，and a simple visual examination can easily identify the cause．Conducting a postmortem il1ustrates what to look for on a failed or failing bearing．Then，understanding the mechanism behind the failure, such as brinelling or fatigue, helps eliminate the source of the problem.Brinelling is one type of bearing failure easily avoided by proper handing andassembly. It is characterized by indentations in the bearing raceway caused by shock loading－such as when a bearing is dropped-or incorrect assembly. Brinelling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)．It may also be caused by improper assembly, Which places a load across the races．Raceway dents also produce noise，vibration，and increased torque.A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turning．This problem is called false brinelling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brinelling acts like an abrasive, further contaminating the bearing. Unlike brinelling, false binelling is often indicated by a reddish color from fretting corrosion in the lubricant.False brinelling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brinelling during transit.Seizures can be caused by a lack of internal clearance, improper lubrication, or excessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color，usually to blue-black or straw colored．Friction also causes stress in the retainer，which can break and hasten bearing failure．Premature material fatigue is caused by a high load or excessive preload．When these conditions are unavoidable，bearing life should be carefully calculated so that a maintenance scheme can be worked out．Another solution for fighting premature fatigue is changing material．When standard bearing materials，such as 440C or SAE 52100，do not guarantee sufficient life，specialty materials can be recommended. In addition，when the problem is traced back to excessive loading，a higher capacity bearing or different configuration may be used．Creep is less common than premature fatigue．In bearings．it is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaft．Creep can be expensive because it causes damage to other components in addition to the bearing．0ther more likely creep indicators are scratches，scuff marks，or discoloration to shaft and bore．To prevent creep damage，the bearing housing and shaft fittings should be visually checked．Misalignment is related to creep in that it is mounting related．If races are misaligned or cocked．The balls track in a noncircumferencial path．The problem is incorrect mounting or tolerancing，or insufficient squareness of the bearing mounting site．Misalignment of more than 1/4·can cause an early failure．Contaminated lubricant is often more difficult to detect than misalignment or creep．Contamination shows as premature wear．Solid contaminants become an abrasive in the lubricant．In addition。
毕业论文外文翻译-轴、联轴器和滚动轴承
附录二外文原文和翻译Shafts、couplings and rolling contact bearingskey words: shafts、couplings、bearingsVirtually all machines contain shafts.The most common shape for shafts is circular and the cross section can be either solid or hollow (hollow shafts can result in weight savings ).Rectangular shafts are sometimes used ,as in screwdriver blades,socket wrenches and control knob stems .A shaft must have adequate torsional strength to transmit torque and not be overstressed. It also be torsionally stiff enough so that one mounted component does not deviate excessively from its original angular position relative to a second component mounted on the same shaft. Generally speaking ,the angle of twist should not exceed one degree in a shaft length equal to 20 diameters.Shafts are mounted inbearings and transmint power through such devices as gears, pullerys, cams and clutches. These devices introduce forces which attempt to bend the shaft; hence, the shaft must be rigid enough to prevent overloading of the supporting bearings. In general, the bending deflection of a shaft should not exceed 0.01 in. per ft of length between bearing supports.In addition, the shaft must be able to sustain a combination of bending and torsional loads. Thus an equivalent load must be consideredwhich takes into account both torsion and bending. Also, the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur.For diameters less than 3 in. , the usual shaft material is cold-rolled ateel containing about 0.4 percent carbon. Shafts are either cold-rolled or forged in sizes from 3 in. to 5 in. ,shafts are forged and machined to size .Pleastic shafts are widely used for light load applications. One advantage of using plastic is safety in electrical applications ,since plastic is a poor conductor of electricity.Components such as gears and pulleys are mounted on shafts by means of key .The design of the key and the corresponding keyway in the shaft must be prperly evaluated. For example ,stress concentrations occur in shafts due to keyways ,and the material removed to form the keyway further weakens the shaft.If shafts are run at cirtical speeds ,severe vibrations can occur which can seriously damage a machine. It is important to know the magnitude of these critical speeds so that they can be avoided. As a general rule of thumb,the difference between the operating speed and the critical speed should be at least 20 percent .Another important aspect of shaft design is the method of directly connecting one shaft to another. This is accomplished by devices such as rigid and flexible couplings.A coupling is a device for connecting the eds of adjacent shafts. In machine construction, ouplings are used to effect a semipermanent connection between adjacent rotating shafts. The connection is permanent in the sense that it is not meant to be broken during the useful life of the machine, but it can be broken and restored in an emergency or when worn parts are replaced.There are several types of shaft couplings, their characteristics depend on the purpose for which they are used. If an exceptionally long shaft is required in a manufacturing plant or a propeller shaft on a ship, it is made in sections that are coupled together with rigid couplings. A common type of rigid coupling consists of two mating radial flanges(disks) that are cttached by key-driven hubs to the eds of adjacent shaft sections and bolted together through the flanges to form a rigid connection. Alignment of the connected shafts is usually effeted by means of a rabbet joint on the face of the flanges.In connecting shafts belonging to separate devices (such as an electric motor and a gearbox ),precise aligning of the shafts is difficult and a flexible coupling is used. This coupling connects theshafts in such a way as to minimize the harmful effects of shaft misalignment. Flexible couplings also permit the shafts to deflect under their separate systems of with one another. Flexible couplings can also serve to reduce the intensity of shock loads and vibrations transmitted from one shaft to another.Virtually all shafts contain rolling contact bearings.The concern of a machine designer with ball and roller bearings is fivefold as follows:(a) life in relation to load; (b) stiffness ,i.e. deflections under load; (c) friction;(d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will usually secure satisfactory performance. The deflection of the bearing elements will become important where loads are high, although this is usuallyof less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard the hostility of the environment.Because the high quality and low price of ball and roller bearings depends on quantity production, the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with ateel which is through-hardened toabout 900HV,although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600 HV. It is not surprising that, owing to the high stresses involved, a predominant form of failure should be metal fatigue, and a good deal of work is currently in progress intended to improve the reliability of this type of bearing. Design can bebased on accepted values of life and it is generral practice in the bearing industry to define the load capacity of the bearing as that value below which 90 lpercent of a batch will exceed a lift of ane million revolutions.Notwithstanding the fact that responsibility for the basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by abutting against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provides with a radius or chamfer to allow space for this .Where life is not the determining factor in design, it is usual to determine maximum loading by the amount towhich a bearing will deflect under load. Thus the concept of “static load-carrying capacity” is understood to mean the load that can be alpplied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has beendetermined by practical experience as the load which when applied to a bearing results in a total deformation of the rolling element and raceway at any point of contact not exceeding 0.01 percent of the rolling-element diameter. This would correspond to a permanent deformation of 0.00025 mm for a ball 25mm in diameter.The successful functioning of many bearing depends upon providing them with adequate protection against their environment, and in some circumstances the enviroration of the bering surfaces. Achievement of the correct functioning of seals is an essential part of bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on the basis of the approlpriate bearing theory. Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.References:1 Erickson.Belt and Application for Engineers.Marcel Dekker.Inc,19972 South,Mancuso.Mechanical Power Transmission Components.1994轴、联轴器和滚动轴承关键词：轴、联轴器、轴承实际上，几乎所有的机器中都装有轴。
《机械设计基础》常用单词中英文对照
《机械设计基础》常用单词中英文对照- common words in Basis of Mechanical Designing一画1.V带V belt2.力force3.力矩moment4.工作载荷serving load5.干摩擦dry friction6.飞轮flier, flywheel7.内圈inner ring8切向键tangential key9.切应力tangential stress10.切削cutting11.双头螺柱stud12.尺寸dimension13.尺寸公差dimensional tolerance14.计算载荷calculating load15.主动轴drive shaft16.凸轮cam17.加工working18.半圆键half round key19.外圈outer ring.20.失效failure21.尼龙nylon22.平键flat key23.打滑slippage24.正火normalizing treatment25.正应力normal stress26.优化设计optimum design27.冲压punching28.动平衡dynamic balance29动载荷moving load30.压力pressure31.压应力compressive stress32压强pressure intensity33.压缩compress34.压缩应力compressive stress35.合金钢alloy steel36.向心轴承centripetal stress37.向心推力轴承centripetal thrust bearing38.导向键guide key39.导轨guide track40当量动载荷equivalent dynamic load41.曲柄 crank42.曲轴crank axle43.曲率半径curvature radius44.有色金属non ferrous metal45.机构mechanism46.机架framework47.机座machine base48.机械machine49.机械加工mechanical working50.机械零件machine element51.机器machine52.灰铸铁gray cast iron53.自锁self locking54.行星轮系planetary gear train55.许用应力allowable stress56.防松locking57.刨削planning58.寿命life59.应力stress60.应力集中stress concentration61.应变strain62.扭转torsion63扭转角angle of torsion64.抗压强度compression strength65抗拉强度tensile strength66.抗弯强度bending strength67.材料material68.极限应力limit stress69.极惯性矩polar moment of inertial70.花键spline71.连杆connecting rod72.周转轮系epicyclic gear train73.屈服强度yield strength74.底板base plate75.底座underframe76.径向力radial force77.径向当量动载荷radial equivalent dynamic load78.径向轴承journal bearing79.径向基本额定动载荷radial elementary rated life80.性能performance81.承载量load carrying capacity82.拉力pulling force83.拉伸tension84.拉伸应力tensile stress85.油膜oil film86.泊松比Poisson’s ratio87.直径diameter88.空心轴hollow axle89.空气轴承air bearing90表面处理surface treatment91.表面淬火surface quenching92转矩torque93.金属材料metallic material94.青铜合金bronze alloy95.非金属材料non metallic material96.齿轮gear97.齿轮模数module of gear teeth98.齿数tooth number99.保持架holding frame100.变应力dynamic stress101.变形deflection, deformation102.变载荷dynamic load103.轮系gear train104.垫片shim105.垫圈washer106.复合材料composite material107.带传动belt driving108.弯曲bend109.弯曲应力bending stress110.弯曲强度bending strength111.弯矩bending moment112.挡圈retaining ring113.残余应力residual stress114.残余变形residual deformation115.点蚀pitting116.相对运动relative motion117.相对滑动relative sliding118.相对滚动relative rolling motion119.矩形花键square key120.结构structure121.结构设计structural design121.结构钢structural steel122.耐磨性wearing quality123.脉动循环应力repeated stress124.轴shaft125.轴瓦bushing126.轴向力axial force127.轴向当量动载荷axial equivalent dynamic load 128.轴向基本额定动载荷axial elementary rated life129.轴承bearing130.轴承合金bearing metal131.轴承油沟grooves in bearing132.轴承衬bearing bush133.轴承座bearing block134.轴承盖bearing cap135.轴环axle ring136.轴肩shaft neck137.轴套shaft sleeve138.退刀槽tool escape139.钢材steel140.钩头楔键gib head key150.钩头螺栓gib head bolt151.挺杆tappet, tapper152.圆柱销cylindrical pin153.圆锥销cone pin154.圆螺母circular nut155.流体动力润滑hydrodynamic lubrication 156.流体静力润滑hydrostatic lubrication 157.润滑lubrication158.润滑油膜lubricant film159.热处理heat treatment160.热平衡heat balance161.疲劳fatigue162.疲劳失效fatigue failure163.疲劳寿命fatigue Life164.疲劳强度fatigue strength165.疲劳裂纹fatigue cracking166.离合器clutch167.紧定螺钉tightening screw168.胶合seizing of teeth169.能量energy170.脆性材料brittle material171.调质钢quenched and tempered steel 172.载荷load173.载荷谱load spectrum174.通用零件universal element175.速度velocity176.部件parts177.铆接riveting178.陶瓷ceramics179.预紧pretighten180.高速传动轴high speed drive shaft181.偏心载荷eccentric load182.偏转角deflection angle183.减速器reductor184.剪切应力shearing stress185.剪切应力shear stress186.基本额定动载荷elementary rated dynamic load 187.基本额定寿命elementary rated life188.密封seal189.密度density190.弹性变形elastic deformation191.弹性流体动力润滑elastohydrodynamic lubrication 192.弹性啮合elastic engagement193.弹性滑动elastic slippage194.弹性模量modulus of elasticity195.弹簧spring196.弹簧垫圈spring washer197.惯性力inertial force198.惯性矩moment of inertia199.接触应力contact stress200.接触角Contact Angle201.推力轴承thrust bearing202.断裂break203.液压hydraulic pressure204.混合润滑mixed lubrication205.渐开线花键involute spline206.焊接welding207.球形阀globe valve208.球墨铸铁nodular cast iron209.粗糙度roughness210.铜合金copper alloy211.铝合金aluminum alloy212.铰链hinge213.黄铜brass214.剩余预紧力residual initial tightening load215.喷丸sand blast216.强度strength217.强度极限ultimate strength218.最小油膜厚度minimum film thickness219.棘轮传动ratchet wheel220.滑动轴承sliding bearing221.滑块slide block222.滑键slide key223硬度hardness224.联轴器coupling225.装配assembly226.铸件casting227.铸钢cast steel228.铸造cast229.铸铁cast iron230.铸铝cast aluminum231.链chain232.链轮chain wheel233.销pin234.销钉联接pin connection235.塑性材料ductile material236.塑性变形plastic deformation 237.塑料plastics238.摇杆rocker239.楔键wedge key240.滚动体Rolling Body241.滚动轴承rolling bearing242.滚压rolling243.滚珠丝杆ball leading screw 244.锡青铜tin bronze245.锥形阀cone valve246.键key247.键槽keyways248.碳化carbonization249.碳素钢carbon steel250.稳定性stability251.腐蚀corrosion252.锻件forged piece253.锻钢forged steel254.锻造forging255.静压轴承hydrostatic bearing 256.静应力steady stress257.静载荷／应力static load／stress 258.摩擦friction259.摩擦力friction force260.摩擦功friction work261.摩擦系数friction coefficient 262.摩擦角friction angle263.摩擦学tribology264.槽轮sheave wheel265.橡胶rubber266.箱体box267.磨削grinding268.磨损wear269.磨损过程wear process270.螺母nut271.螺纹screw272.螺纹threads273.螺纹联接threaded and coupled 274.螺钉pitch275.螺栓bolt276.螺栓联接bolting277.螺旋传动screw-driven机械设计名词术语中英对照机械设计名词术语中英文对照表Chinese English阿基米德蜗杆Archimedes worm安全系数safety factor; factor of safety安全载荷safe load凹面、凹度concavity扳手wrench板簧flat leaf spring半圆键woodruff key变形deformation摆杆oscillating bar摆动从动件oscillating follower摆动从动件凸轮机构cam with oscillating follower 摆动导杆机构oscillating guide-bar mechanism摆线齿轮cycloidal gear摆线齿形cycloidal tooth profile摆线运动规律cycloidal motion摆线针轮cycloidal-pin wheel包角angle of contact保持架cage背对背安装back-to-back arrangement背锥back cone ；normal cone背锥角back angle背锥距back cone distance比例尺scale比热容specific heat capacity闭式链closed kinematic chain闭链机构closed chain mechanism臂部arm变频器frequency converters变频调速frequency control of motor speed变速speed change变速齿轮change gear ; change wheel变位齿轮modified gear变位系数modification coefficient标准齿轮standard gear标准直齿轮standard spur gear表面质量系数superficial mass factor表面传热系数surface coefficient of heat transfer 表面粗糙度surface roughness并联式组合combination in parallel并联机构parallel mechanism并联组合机构parallel combined mechanism并行工程concurrent engineering并行设计concurred design, CD不平衡相位phase angle of unbalance不平衡imbalance (or unbalance)不平衡量amount of unbalance不完全齿轮机构intermittent gearing波发生器wave generator波数number of waves补偿compensation参数化设计parameterization design, PD残余应力residual stress操纵及控制装置operation control device槽轮Geneva wheel槽轮机构Geneva mechanism ；Maltese cross 槽数Geneva numerate槽凸轮groove cam侧隙backlash差动轮系differential gear train差动螺旋机构differential screw mechanism差速器differential常用机构conventional mechanism; mechanism in common use车床lathe承载量系数bearing capacity factor承载能力bearing capacity成对安装paired mounting尺寸系列dimension series齿槽tooth space齿槽宽spacewidth齿侧间隙backlash齿顶高addendum齿顶圆addendum circle齿根高dedendum《机械设计基础》常用单词中英文对照寿命life应力stress应力集中stress concentration应变strain扭转torsion扭转角angle of torsion抗压强度compression strength抗拉强度tensile strength抗弯强度bending strength材料material极限应力limit stress极惯性矩polar moment of inertial花键spline连杆connecting rod周转轮系epicyclic gear train屈服强度yield strength底板base plate底座underframe径向力radial force径向当量动载荷radial equivalent dynamic load 径向轴承journal bearing径向基本额定动载荷radial elementary rated life 性能performance承载量load carrying capacity拉力pulling force拉伸tension拉伸应力tensile stress油膜oil film泊松比Poisson’s ratio直径diameter空心轴hollow axle空气轴承air bearing表面处理surface treatment表面淬火surface quenching转矩torque金属材料metallic material青铜合金bronze alloy非金属材料non metallic material齿轮gear齿轮模数module of gear teeth齿数tooth number保持架holding frame变应力dynamic stress变形deflection, deformation变载荷dynamic load。
机械专业中英文对照翻译大全.
机械专业英语词汇中英文对照翻译一览表陶瓷ceramics合成纤维synthetic fibre电化学腐蚀electrochemical corrosion车架automotive chassis悬架suspension转向器redirector变速器speed changer板料冲压sheet metal parts孔加工spot facing machining车间workshop工程技术人员engineer气动夹紧pneuma lock数学模型mathematical model画法几何descriptive geometry机械制图Mechanical drawing投影projection视图view剖视图profile chart标准件standard component零件图part drawing装配图assembly drawing尺寸标注size marking技术要求technical requirements刚度rigidity内力internal force位移displacement截面section疲劳极限fatigue limit断裂fracture塑性变形plastic distortion脆性材料brittleness material刚度准则rigidity criterion垫圈washer垫片spacer直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear直齿锥齿轮straight bevel gear运动简图kinematic sketch齿轮齿条pinion and rack蜗杆蜗轮worm and worm gear虚约束passive constraint曲柄crank摇杆racker凸轮cams共轭曲线conjugate curve范成法generation method定义域definitional domain值域range导数\\微分differential coefficient求导derivation定积分definite integral不定积分indefinite integral曲率curvature偏微分partial differential毛坯rough游标卡尺slide caliper千分尺micrometer calipers攻丝tap二阶行列式second order determinant 逆矩阵inverse matrix线性方程组linear equations概率probability随机变量random variable排列组合permutation and combination 气体状态方程equation of state of gas动能kinetic energy势能potential energy机械能守恒conservation of mechanical energy动量momentum桁架truss轴线axes余子式cofactor逻辑电路logic circuit触发器flip-flop脉冲波形pulse shape数模digital analogy液压传动机构fluid drive mechanism机械零件mechanical parts淬火冷却quench淬火hardening回火tempering调质hardening and tempering磨粒abrasive grain结合剂bonding agent砂轮grinding wheel后角clearance angle龙门刨削planing主轴spindle主轴箱headstock卡盘chuck加工中心machining center 车刀lathe tool车床lathe钻削镗削bore车削turning磨床grinder基准benchmark钳工locksmith锻forge压模stamping焊weld拉床broaching machine拉孔broaching装配assembling铸造found流体动力学fluid dynamics流体力学fluid mechanics加工machining液压hydraulic pressure切线tangent机电一体化mechanotronics mechanical-electrical integration气压air pressure pneumatic pressure稳定性stability介质medium液压驱动泵fluid clutch液压泵hydraulic pump阀门valve失效invalidation强度intensity载荷load应力stress安全系数safty factor可靠性reliability螺纹thread螺旋helix键spline销pin滚动轴承rolling bearing滑动轴承sliding bearing弹簧spring制动器arrester brake十字结联轴节crosshead联轴器coupling链chain皮带strap精加工finish machining粗加工rough machining变速箱体gearbox casing腐蚀rust氧化oxidation磨损wear耐用度durability随机信号random signal离散信号discrete signal超声传感器ultrasonic sensor 集成电路integrate circuit挡板orifice plate残余应力residual stress套筒sleeve扭力torsion冷加工cold machining电动机electromotor汽缸cylinder过盈配合interference fit热加工hotwork摄像头CCD camera倒角rounding chamfer优化设计optimal design工业造型设计industrial moulding design有限元finite element滚齿hobbing插齿gear shaping伺服电机actuating motor铣床milling machine钻床drill machine镗床boring machine步进电机stepper motor丝杠screw rod导轨lead rail组件subassembly可编程序逻辑控制器Programmable Logic Controller PLC 电火花加工electric spark machining电火花线切割加工electrical discharge wire - cutting 相图phase diagram热处理heat treatment固态相变solid state phase changes有色金属nonferrous metal陶瓷ceramics合成纤维synthetic fibre电化学腐蚀electrochemical corrosion车架automotive chassis悬架suspension转向器redirector变速器speed changer板料冲压sheet metal parts孔加工spot facing machining车间workshop工程技术人员engineer气动夹紧pneuma lock数学模型mathematical model画法几何descriptive geometry机械制图Mechanical drawing投影projection视图view剖视图profile chart标准件standard component零件图part drawing装配图assembly drawing尺寸标注size marking技术要求technical requirements刚度rigidity内力internal force位移displacement截面section疲劳极限fatigue limit断裂fracture塑性变形plastic distortion脆性材料brittleness material刚度准则rigidity criterion垫圈washer垫片spacer直齿圆柱齿轮straight toothed spur gear 斜齿圆柱齿轮helical-spur gear直齿锥齿轮straight bevel gear运动简图kinematic sketch齿轮齿条pinion and rack蜗杆蜗轮worm and worm gear虚约束passive constraint曲柄crank摇杆racker凸轮cams共轭曲线conjugate curve范成法generation method定义域definitional domain值域range导数\\微分differential coefficient求导derivation定积分definite integral不定积分indefinite integral曲率curvature偏微分partial differential毛坯rough游标卡尺slide caliper千分尺micrometer calipers攻丝tap二阶行列式second order determinant 逆矩阵inverse matrix线性方程组linear equations概率probability随机变量random variable排列组合permutation and combination气体状态方程equation of state of gas动能kinetic energy势能potential energy机械能守恒conservation of mechanical energy 动量momentum桁架truss轴线axes余子式cofactor逻辑电路logic circuit触发器flip-flop脉冲波形pulse shape数模digital analogy液压传动机构fluid drive mechanism机械零件mechanical parts淬火冷却quench淬火hardening回火tempering调质hardening and tempering磨粒abrasive grain结合剂bonding agent砂轮grinding wheel Assembly line 组装线Layout 布置图Conveyer 流水线物料板Rivet table 拉钉机Rivet gun 拉钉枪Screw driver 起子Pneumatic screw driver 气动起子worktable 工作桌OOBA 开箱检查fit together 组装在一起fasten 锁紧(螺丝)fixture 夹具(治具)pallet 栈板barcode 条码barcode scanner 条码扫描器fuse together 熔合fuse machine热熔机repair修理operator作业员QC品管supervisor 课长ME 制造工程师MT 制造生技cosmetic inspect 外观检查inner parts inspect 内部检查thumb screw 大头螺丝lbs. inch 镑、英寸EMI gasket 导电条front plate 前板rear plate 后板chassis 基座bezel panel 面板power button 电源按键reset button 重置键Hi-pot test of SPS 高源高压测试Voltage switch of SPS 电源电压接拉键sheet metal parts 冲件plastic parts 塑胶件SOP 制造作业程序material check list 物料检查表work cell 工作间trolley 台车carton 纸箱sub-line 支线left fork 叉车personnel resource department 人力资源部production department生产部门planning department企划部QC Section品管科stamping factory冲压厂painting factory烤漆厂molding factory成型厂common equipment常用设备uncoiler and straightener整平机punching machine 冲床robot机械手hydraulic machine油压机lathe车床planer |plein|刨床miller铣床grinder磨床linear cutting线切割electrical sparkle电火花welder电焊机staker=reviting machine铆合机position职务president董事长general manager总经理special assistant manager特助factory director厂长department director部长deputy manager | =vice manager副理section supervisor课长deputy section supervisor =vice section superisor副课长group leader/supervisor组长line supervisor线长assistant manager助理to move, to carry, to handle搬运be put in storage入库pack packing包装to apply oil擦油to file burr 锉毛刺final inspection终检to connect material接料to reverse material 翻料wet station沾湿台Tiana天那水cleaning cloth抹布to load material上料to unload material卸料to return material/stock to退料scraped |\\'skr?pid|报废scrape ..v.刮;削deficient purchase来料不良manufacture procedure制程deficient manufacturing procedure制程不良oxidation |\\' ksi\\'dei?n|氧化scratch刮伤dents压痕defective upsiding down抽芽不良defective to staking铆合不良embedded lump镶块feeding is not in place送料不到位stamping-missing漏冲production capacity生产力education and training教育与训练proposal improvement提案改善spare parts=buffer备件forklift叉车trailer=long vehicle拖板车compound die合模die locker锁模器pressure plate=plate pinch压板bolt螺栓administration/general affairs dept总务部automatic screwdriver电动启子thickness gauge厚薄规gauge(or jig)治具power wire电源线buzzle蜂鸣器defective product label不良标签identifying sheet list标示单location地点present members出席人员subject主题conclusion结论decision items决议事项responsible department负责单位pre-fixed finishing date预定完成日approved by / checked by / prepared by核准/审核/承办PCE assembly production schedule sheet PCE组装厂生产排配表model机锺work order工令revision版次remark备注production control confirmation生产确认checked by初审approved by核准department部门stock age analysis sheet 库存货龄分析表on-hand inventory现有库存available material良品可使用obsolete material良品已呆滞to be inspected or reworked 待验或重工total合计cause description原因说明part number/ P/N 料号type形态item/group/class类别quality品质prepared by制表notes说明year-end physical inventory difference analysis sheet 年终盘点差异分析表physical inventory盘点数量physical count quantity帐面数量difference quantity差异量cause analysis原因分析raw materials原料materials物料finished product成品semi-finished product半成品packing materials包材good product/accepted goods/ accepted parts/good parts 良品defective product/non-good parts不良品disposed goods处理品warehouse/hub仓库on way location在途仓oversea location海外仓spare parts physical inventory list备品盘点清单spare molds location模具备品仓skid/pallet栈板tox machine自铆机wire EDM线割EDM放电机coil stock卷料sheet stock片料tolerance工差score=groove压线cam block滑块pilot导正筒trim剪外边pierce剪内边drag form压锻差pocket for the punch head挂钩槽slug hole废料孔feature die公母模expansion dwg展开图radius半径shim(wedge)楔子torch-flame cut火焰切割set screw止付螺丝form block折刀stop pin定位销round pierce punch=die button圆冲子shape punch=die insert异形子stock locater block定位块under cut=scrap chopper清角active plate活动板baffle plate挡块cover plate盖板male die公模female die母模groove punch压线冲子air-cushion eject-rod气垫顶杆spring-box eject-plate弹簧箱顶板bushing block衬套insert 入块club car高尔夫球车capability能力parameter参数factor系数phosphate皮膜化成viscosity涂料粘度alkalidipping脱脂main manifold主集流脉bezel斜视规blanking穿落模dejecting顶固模demagnetization去磁;消磁high-speed transmission高速传递heat dissipation热传rack上料degrease脱脂rinse水洗alkaline etch龄咬desmut剥黑膜D.I. rinse纯水次Chromate铬酸处理Anodize阳性处理seal封孔revision版次part number/P/N料号good products良品scraped products报放心品defective products不良品finished products成品disposed products处理品barcode条码flow chart流程表单assembly组装stamping冲压molding成型spare parts=buffer备品coordinate座标dismantle the die折模auxiliary fuction辅助功能poly-line多义线heater band 加热片thermocouple热电偶sand blasting喷沙grit 砂砾derusting machine除锈机degate打浇口dryer烘干机induction感应induction light感应光response=reaction=interaction感应ram连杆edge finder巡边器concave凸convex凹short射料不足nick缺口speck瑕??shine亮班splay 银纹gas mark焦痕delamination起鳞cold slug冷块blush 导色gouge沟槽;凿槽satin texture段面咬花witness line证示线patent专利grit沙砾granule=peuet=grain细粒grit maker抽粒机cushion缓冲magnalium镁铝合金magnesium镁金metal plate钣金lathe车mill锉plane刨grind磨drill铝boring镗blinster气泡fillet镶;嵌边through-hole form通孔形式voller pin formality滚针形式cam driver铡楔shank摸柄crank shaft曲柄轴augular offset角度偏差velocity速度production tempo生产进度现状torque扭矩spline=the multiple keys花键quenching淬火tempering回火annealing退火carbonization碳化tungsten high speed steel钨高速的moly high speed steel钼高速的organic solvent有机溶剂bracket小磁导liaison联络单volatile挥发性resistance电阻ion离子titrator滴定仪beacon警示灯coolant冷却液crusher破碎机阿基米德蜗杆Archimedes worm安全系数safety factor; factor of safety安全载荷safe load凹面、凹度concavity扳手wrench板簧flat leaf spring半圆键woodruff key变形deformation摆杆oscillating bar摆动从动件oscillating follower摆动从动件凸轮机构cam with oscillating follower 摆动导杆机构oscillating guide-bar mechanism 摆线齿轮cycloidal gear摆线齿形cycloidal tooth profile摆线运动规律cycloidal motion摆线针轮cycloidal-pin wheel包角angle of contact保持架cage背对背安装back-to-back arrangement背锥back cone ；normal cone背锥角back angle背锥距back cone distance比例尺scale比热容specific heat capacity闭式链closed kinematic chain闭链机构closed chain mechanism臂部arm变频器frequency converters变频调速frequency control of motor speed 变速speed change变速齿轮change gear change wheel变位齿轮modified gear变位系数modification coefficient标准齿轮standard gear标准直齿轮standard spur gear表面质量系数superficial mass factor表面传热系数surface coefficient of heat transfer 表面粗糙度surface roughness并联式组合combination in parallel并联机构parallel mechanism并联组合机构parallel combined mechanism并行工程concurrent engineering并行设计concurred design, CD不平衡相位phase angle of unbalance不平衡imbalance (or unbalance)不平衡量amount of unbalance不完全齿轮机构intermittent gearing波发生器wave generator波数number of waves补偿compensation参数化设计parameterization design, PD残余应力residual stress操纵及控制装置operation control device槽轮Geneva wheel槽轮机构Geneva mechanism ；Maltese cross 槽数Geneva numerate槽凸轮groove cam侧隙backlash差动轮系differential gear train差动螺旋机构differential screw mechanism差速器differential常用机构conventional mechanism; mechanism in common use车床lathe承载量系数bearing capacity factor承载能力bearing capacity成对安装paired mounting尺寸系列dimension series齿槽tooth space齿槽宽spacewidth齿侧间隙backlash齿顶高addendum齿顶圆addendum circle齿根高dedendum齿根圆dedendum circle齿厚tooth thickness齿距circular pitch齿宽face width齿廓tooth profile齿廓曲线tooth curve齿轮gear齿轮变速箱speed-changing gear boxes齿轮齿条机构pinion and rack齿轮插刀pinion cutter; pinion-shaped shaper cutter 齿轮滚刀hob ,hobbing cutter齿轮机构gear齿轮轮坯blank齿轮传动系pinion unit齿轮联轴器gear coupling齿条传动rack gear齿数tooth number齿数比gear ratio齿条rack齿条插刀rack cutter; rack-shaped shaper cutter齿形链、无声链silent chain齿形系数form factor齿式棘轮机构tooth ratchet mechanism插齿机gear shaper重合点coincident points重合度contact ratio冲床punch传动比transmission ratio, speed ratio传动装置gearing; transmission gear传动系统driven system传动角transmission angle传动轴transmission shaft串联式组合combination in series串联式组合机构series combined mechanism 串级调速cascade speed control创新innovation creation创新设计creation design垂直载荷、法向载荷normal load唇形橡胶密封lip rubber seal磁流体轴承magnetic fluid bearing从动带轮driven pulley从动件driven link, follower从动件平底宽度width of flat-face从动件停歇follower dwell从动件运动规律follower motion从动轮driven gear粗线bold line粗牙螺纹coarse thread大齿轮gear wheel打包机packer打滑slipping带传动belt driving带轮belt pulley带式制动器band brake单列轴承single row bearing单向推力轴承single-direction thrust bearing单万向联轴节single universal joint单位矢量unit vector当量齿轮equivalent spur gear; virtual gear当量齿数equivalent teeth number; virtual number of teeth 当量摩擦系数equivalent coefficient of friction当量载荷equivalent load刀具cutter导数derivative倒角chamfer导热性conduction of heat导程lead导程角lead angle等加等减速运动规律parabolic motion; constant acceleration and deceleration motion等速运动规律uniform motion; constant velocity motion等径凸轮conjugate yoke radial cam等宽凸轮constant-breadth cam等效构件equivalent link等效力equivalent force等效力矩equivalent moment of force等效量equivalent等效质量equivalent mass等效转动惯量equivalent moment of inertia等效动力学模型dynamically equivalent model底座chassis低副lower pair点划线chain dotted line（疲劳）点蚀pitting垫圈gasket垫片密封gasket seal碟形弹簧belleville spring顶隙bottom clearance定轴轮系ordinary gear train; gear train with fixed axes 动力学dynamics动密封kinematical seal动能dynamic energy动力粘度dynamic viscosity动力润滑dynamic lubrication动平衡dynamic balance动平衡机dynamic balancing machine动态特性dynamic characteristics动态分析设计dynamic analysis design动压力dynamic reaction动载荷dynamic load端面transverse plane端面参数transverse parameters端面齿距transverse circular pitch端面齿廓transverse tooth profile端面重合度transverse contact ratio端面模数transverse module端面压力角transverse pressure angle锻造forge对称循环应力symmetry circulating stress对心滚子从动件radial (or in-line ) roller follower对心直动从动件radial (or in-line ) translating follower对心移动从动件radial reciprocating follower对心曲柄滑块机构in-line slider-crank (or crank-slider) mechanism多列轴承multi-row bearing多楔带poly V-belt多项式运动规律polynomial motion多质量转子rotor with several masses惰轮idle gear额定寿命rating life额定载荷load ratingII 级杆组dyad发生线generating line发生面generating plane法面normal plane法面参数normal parameters法面齿距normal circular pitch法面模数normal module法面压力角normal pressure angle法向齿距normal pitch法向齿廓normal tooth profile法向直廓蜗杆straight sided normal worm法向力normal force反馈式组合feedback combining反向运动学inverse ( or backward) kinematics 反转法kinematic inversion反正切Arctan范成法generating cutting仿形法form cutting方案设计、概念设计concept design, CD防振装置shockproof device飞轮flywheel飞轮矩moment of flywheel非标准齿轮nonstandard gear非接触式密封non-contact seal非周期性速度波动aperiodic speed fluctuation非圆齿轮non-circular gear粉末合金powder metallurgy分度线reference line; standard pitch line分度圆reference circle; standard (cutting) pitch circle 分度圆柱导程角lead angle at reference cylinder分度圆柱螺旋角helix angle at reference cylinder分母denominator分子numerator分度圆锥reference cone; standard pitch cone分析法analytical method封闭差动轮系planetary differential复合铰链compound hinge复合式组合compound combining复合轮系compound (or combined) gear train 复合平带compound flat belt复合应力combined stress复式螺旋机构Compound screw mechanism复杂机构complex mechanism杆组Assur group干涉interference刚度系数stiffness coefficient刚轮rigid circular spline钢丝软轴wire soft shaft刚体导引机构body guidance mechanism刚性冲击rigid impulse (shock)刚性转子rigid rotor刚性轴承rigid bearing刚性联轴器rigid coupling高度系列height series高速带high speed belt高副higher pair格拉晓夫定理Grashoff`s law根切undercutting公称直径nominal diameter高度系列height series功work工况系数application factor工艺设计technological design工作循环图working cycle diagram工作机构operation mechanism工作载荷external loads工作空间working space工作应力working stress工作阻力effective resistance工作阻力矩effective resistance moment 公法线common normal line公共约束general constraint公制齿轮metric gears功率power功能分析设计function analyses design 共轭齿廓conjugate profiles共轭凸轮conjugate cam构件link鼓风机blower固定构件fixed link; frame固体润滑剂solid lubricant关节型操作器jointed manipulator惯性力inertia force惯性力矩moment of inertia ,shaking moment 惯性力平衡balance of shaking force惯性力完全平衡full balance of shaking force惯性力部分平衡partial balance of shaking force 惯性主矩resultant moment of inertia惯性主失resultant vector of inertia冠轮crown gear广义机构generation mechanism广义坐标generalized coordinate轨迹生成path generation轨迹发生器path generator滚刀hob滚道raceway滚动体rolling element滚动轴承rolling bearing滚动轴承代号rolling bearing identification code 滚针needle roller滚针轴承needle roller bearing滚子roller滚子轴承roller bearing滚子半径radius of roller滚子从动件roller follower滚子链roller chain滚子链联轴器double roller chain coupling 滚珠丝杆ball screw滚柱式单向超越离合器roller clutch过度切割undercutting函数发生器function generator函数生成function generation含油轴承oil bearing耗油量oil consumption耗油量系数oil consumption factor赫兹公式H. Hertz equation合成弯矩resultant bending moment合力resultant force合力矩resultant moment of force黑箱black box横坐标abscissa互换性齿轮interchangeable gears花键spline滑键、导键feather key滑动轴承sliding bearing滑动率sliding ratio滑块slider环面蜗杆toroid helicoids worm环形弹簧annular spring缓冲装置shocks; shock-absorber灰铸铁grey cast iron回程return回转体平衡balance of rotors混合轮系compound gear train积分integrate机电一体化系统设计mechanical-electrical integration system design机构mechanism机构分析analysis of mechanism机构平衡balance of mechanism机构学mechanism机构运动设计kinematic design of mechanism机构运动简图kinematic sketch of mechanism机构综合synthesis of mechanism机构组成constitution of mechanism机架frame, fixed link机架变换kinematic inversion机器machine机器人robot机器人操作器manipulator机器人学robotics技术过程technique process技术经济评价technical and economic evaluation 技术系统technique system机械machinery机械创新设计mechanical creation design, MCD 机械系统设计mechanical system design, MSD 机械动力分析dynamic analysis of machinery机械动力设计dynamic design of machinery机械动力学dynamics of machinery机械的现代设计modern machine design机械系统mechanical system机械利益mechanical advantage机械平衡balance of machinery机械手manipulator机械设计machine design; mechanical design机械特性mechanical behavior机械调速mechanical speed governors机械效率mechanical efficiency机械原理theory of machines and mechanisms机械运转不均匀系数coefficient of speed fluctuation机械无级变速mechanical stepless speed changes基础机构fundamental mechanism基本额定寿命basic rating life基于实例设计case-based design,CBD基圆base circle基圆半径radius of base circle基圆齿距base pitch基圆压力角pressure angle of base circle基圆柱base cylinder基圆锥base cone急回机构quick-return mechanism急回特性quick-return characteristics急回系数advance-to return-time ratio急回运动quick-return motion棘轮ratchet棘轮机构ratchet mechanism棘爪pawl极限位置extreme (or limiting) position极位夹角crank angle between extreme (or limiting) positions计算机辅助设计computer aided design, CAD计算机辅助制造computer aided manufacturing, CAM计算机集成制造系统computer integrated manufacturing system, CIMS计算力矩factored moment; calculation moment计算弯矩calculated bending moment加权系数weighting efficient加速度acceleration加速度分析acceleration analysis加速度曲线acceleration diagram尖点pointing; cusp尖底从动件knife-edge follower间隙backlash间歇运动机构intermittent motion mechanism减速比reduction ratio减速齿轮、减速装置reduction gear减速器speed reducer减摩性anti-friction quality渐开螺旋面involute helicoid渐开线involute渐开线齿廓involute profile渐开线齿轮involute gear渐开线发生线generating line of involute渐开线方程involute equation渐开线函数involute function渐开线蜗杆involute worm渐开线压力角pressure angle of involute渐开线花键involute spline简谐运动simple harmonic motion键key键槽keyway交变应力repeated stress交变载荷repeated fluctuating load交叉带传动cross-belt drive交错轴斜齿轮crossed helical gears胶合scoring角加速度angular acceleration角速度angular velocity角速比angular velocity ratio角接触球轴承angular contact ball bearing角接触推力轴承angular contact thrust bearing 角接触向心轴承angular contact radial bearing 角接触轴承angular contact bearing铰链、枢纽hinge校正平面correcting plane接触应力contact stress接触式密封contact seal阶梯轴multi-diameter shaft结构structure结构设计structural design截面section节点pitch point节距circular pitch; pitch of teeth节线pitch line节圆pitch circle节圆齿厚thickness on pitch circle节圆直径pitch diameter节圆锥pitch cone节圆锥角pitch cone angle解析设计analytical design紧边tight-side紧固件fastener径节diametral pitch径向radial direction径向当量动载荷dynamic equivalent radial load径向当量静载荷static equivalent radial load径向基本额定动载荷basic dynamic radial load rating径向基本额定静载荷basic static radial load tating径向接触轴承radial contact bearing径向平面radial plane径向游隙radial internal clearance径向载荷radial load径向载荷系数radial load factor径向间隙clearance静力static force静平衡static balance静载荷static load静密封static seal局部自由度passive degree of freedom矩阵matrix矩形螺纹square threaded form锯齿形螺纹buttress thread form矩形牙嵌式离合器square-jaw positive-contact clutch 绝对尺寸系数absolute dimensional factor绝对运动absolute motion绝对速度absolute velocity均衡装置load balancing mechanism抗压强度compression strength开口传动open-belt drive开式链open kinematic chain开链机构open chain mechanism可靠度degree of reliability可靠性reliability可靠性设计reliability design, RD空气弹簧air spring空间机构spatial mechanism空间连杆机构spatial linkage空间凸轮机构spatial cam空间运动副spatial kinematic pair空间运动链spatial kinematic chain 空转idle宽度系列width series框图block diagram雷诺方程Reynolds‘s equation离心力centrifugal force离心应力centrifugal stress离合器clutch离心密封centrifugal seal理论廓线pitch curve理论啮合线theoretical line of action 隶属度membership力force力多边形force polygon力封闭型凸轮机构force-drive (or force-closed) cam mechanism力矩moment力平衡equilibrium力偶couple力偶矩moment of couple连杆connecting rod, coupler连杆机构linkage连杆曲线coupler-curve连心线line of centers链chain链传动装置chain gearing链轮sprocket sprocket-wheel sprocket gear chain wheel联组V 带tight-up V belt联轴器coupling shaft coupling两维凸轮two-dimensional cam临界转速critical speed六杆机构six-bar linkage龙门刨床double Haas planer轮坯blank。
机械专业毕业论文外文翻译
附录一英文科技文献翻译英文原文：Experimental investigation of laser surface textured parallel thrust bearingsPerformance enhancements by laser surface texturing (LST) of parallel-thrust bearings is experimentally investigated. Testresults are compared with a theoretical model and good correlation is found over the relevant operating conditions. A compari-son of the performance of unidirectional and bi-directional partial-LST bearings with that of a baseline, untextured bearing ispresented showing the benefits of LST in terms of increased clearance and reduced friction.KEY WORDS: fluid film bearings, slider bearings, surface texturing1. IntroductionThe classical theory of hydrodynamic lubrication yields linear (Couette) velocity distribution with zero pressure gradients between smooth parallel surfaces under steady-state sliding. This results in an unstable hydrodynamic film that would collapse under any external force acting normal to the surfaces. However, experience shows that stable lubricating films can deve lop between parallel sliding surfaces, generally because of some mechanism that relaxes one or more of the assumptions of the classical theory.A stable fluid film with sufficient load-carrying capacity in parallel sliding surfaces can be obtained, for example, with macro or micro surface structure of different types. These include waviness [1] and protruding microasperities [2–4]. A good literature review on the subject can be found in Ref. [5]. More recently, laser surface texturing (LST) [6–8], as well as inlet roughening by longitudinal or transverse grooves [9] were suggested to provide load capacity in parallel sliding. The inlet roughness concept of Tonder [9] is based on ‘‘effective clearance’’ reduction in the sliding direction and in this respect it is identical to the par- tial-LST concept described in ref.[10] for generating hydrostatic effect in high-pressure mechanical seals.Very recently Wang et al. [11] demonstrated experimentally a doubling of the load-carrying capacity for the surface- texture design by reactive ion etching of SiCparallel-thrust bearings sliding in water. These simple parallel thrust bearings are usually found in seal-less pumps where the pumped fluid is used as the lubricant for the bearings. Due to the parallel sliding their performance is poorer than more sophisticated tapered or stepped bearings. Brizmer et al. [12] demon-strated the potential of laser surface texturing in the form of regular micro-dimples for providing load-carrying capacity with parallel-thrust bearings. A model of a textured parallelslider was developed and the effect of surface texturing on load-carrying capacitywas analyzed. The optimum parameters of the dimples were found in order to obtainmaximum load-carrying capacity. A micro-dimple ‘‘collective effect’’ was identi-fied that is capable of generating substantial load-carrying capacity, approaching that of optimumconventional thrust bearings. The purpose of the present paper is to investigate experimentally the validity of the model described in Ref. [12] by testing practical thrust bearings and comparing the performance of LST bearings with that of the theoretical predictions and with the performance of standard non-textured bearings2. BackgroundA cross section of the basic model that was analyzed in Ref. [12] is shown in figure1. A slider having a width B is partially textured over a portion Bp =αB of its width.The textured surface consists of multiple dimples with a diameter，depth and area density Sp. As a result of the hydrodynamic pressure generated by the dimples the sliding surfaces will be separated by a clearance depending on the sliding velocity U, the fluid viscosity l and the external load It was found in Ref. [12] that an optimum ratio exists for the parameter that provides maximum dimensionless load-carrying capacity where L isthe bearing length, and this optimum value is hp=1.25. It was further found in Ref. [12] that an optimum value exists for the textured portion a depending onthe bearing aspect ratio L/B. This behavior is shown in figure 2 for a bearing with L/B = 0.75 at various values of the area density Sp. As can be seen in the range of Sp values from 0.18 to 0.72 the optimum a value varies from 0.7 to 0.55, respectively. It can also be seen from figure 2 that for a < 0.85 no optimum value exists for Sp and the maximum load W increases with increasing Sp. Hence, the largest area density that can be practically obtained with the laser texturing is desired. It is also interesting to note from figure 2 the advantage of partial-LST (a < 1) over the full LST (a = 1) for bearing applications. At Sp= 0.5, for example, the load W at a = 0.6 is about three times higher than its value at a = 1. A full account of this behavior is given in Ref. [12].3. ExperimentalThe tested bearings consist of sintered SiC disks 10 mm thick, having 85 mm outer diameter and 40 mm inner diameter. Each bearing (see figure 3) comprises a flat rotor (a) and a six-pad stator (b). The bearings were provided with an original surface finish by lapping to a roughness average Ra= 0.03 lm. Each pad has an aspect ratio of 0.75 when its width is measured along the mean diameter of the stator. The photographs of two partial-LST stators are shown in figure 4 where the textured areas appear as brighter matt surfaces. The first stator indicated (a) is a unidirectional bearing with the partial-LST adjacent to the leading edge of each pad, similar to the model shown in figure 1. The second stator (b) is a bi-directional version of a partial-LST bearing having two equal textured portions, a/2, on each of the pad ends. The laser texturing parameters were the following; dimple depth, dimplediameter and dimple area density Sp= 0.60.03. These dimple dimensions were obtained with 4 pulses of 30 ns duration and 4 mJ each using a 5 kHz pulsating Nd:YAG laser. The textured portion of the unidirectional bearing was a= 0.73 and that of the bi-directional bearing was a= 0.63. As can be seen from figure 2 both these a values should produce load-carrying capacity vary close to the maximum theoret ical value.The test rig is shown schematically in figure 5. An electrical motor turns a spindle to which an upper holder of the rotor is attached. A second lower holder of the stator is fixed to a housing, which rests on a journal bearing and an axial loading mechanism that can freely move in the axial direction. An arm that presses against a load cell and thereby permits friction torque measurements prevents the free rotation of this housing. Axial loading is provided by means of dead weights on a lever and is measured with a second load cell. A proximity probe that is attached to the lower holder of the stator allows on-line measurements of the clearance change between rotor and stator as the hydrodynamiceffects cause axial movement of the housing to which the stator holder is fixed. Tapwater is supplied by gravity from a large tank to the center of the bearing and the leakage from the bearing is collected and re-circulated. A thermocouple adjacent to the outer diameter of the bearing allows monitoring of the water temperature as the water exit the bearing. A PC is used to collect and process data on-line. Hence,theinstantaneous clearance, friction coefficient, bearing speed and exit water temperaturecan be monitored constantly.The test protocol incl udes identifying a reference “zero〞point for the clearance measurements by first loading and then unloading a stationary bearing over the full load range. Then the lowest axial load is applied, the water supply valve is opened and the motor turned on. Axial loading is increased by steps of 40 N and each load step is maintained for 5 min following the stabilization of the friction coefficient ata steady-state value. The bearing speed and water temperature are monitored throughout the test for any irregularities. The test ends when a maximum axial load of 460 N is reached or if the friction coefficient exceeds a value of 0.35. At the end ofthe last load step the motor and water supply are turned off and the reference for the clearance measurements is rechecked. Tests are performed at two speeds of 1500and 3000 rpm corresponding to average sliding velocities of 4.9 and 9.8 m/s, respectively and each test is repeated at least three times.4. Results and discussionAs a first step the validity of the theoretical mode l in Ref. [12] was examined by comparing the theoretical and experimental results of bearing clearance versus bearing load for a unidirectional partial-LST bearing. The results are shown in figure 6 for the two speeds of 1500 and 3000 rpm where the solid and dashed lines correspond to the model and experiment, respectively. As can be seen, the agreement between the model and the experiment is good, with differences of less than 10%, aslong as the load is above 150 N. At lower loads the measured experimental clearances are much larger than the model predictions, particularly at the higher speed of 3000 rpm where at 120 N the measured clearance is 20 lm, which is about 60% higher than the predicted value. It turns out that the combination of such large clearances and relatively low viscosity of the water may result in turbulent fluid film. Hence, the assumption of laminar flow on which the solution of the Reynolds equation in Ref.[12] is based may be violated making the model invalid especially at the higher speed and lowest load. In order to be consistent with the model of Ref. [12] it was decided to limit further comparisons to loads above 150 N.It should be noted here that the first attempts to test the baseline untextured bearing with the original surface finish of Ra= 0.03 lm on both the stator and rotor failed due to extremely high friction even at the lower loads. On the other hand the partial-LST bearing ran smoothly throughout the load range. It was found that the post-LST lapping to completely remove about 2 lm height bulges, which are formed during texturing around the rims of the dimples, resulted in a slightly rougher surface with Ra= 0.04 lm. Hence, the baseline untextured stator was also lapped to the same rough- ness of the partial-LST stator and all subsequent tests were performed with the same Ra value of 0.04 lm for all the tested stators. The rotor surface roughnessand 2.2 lm for the LST and untextured bearings, respectively. As can be seen from figure 7 this ratio of about 3 in favor of the partial-LST bearing is maintained over the entire load range.Figure 8 presents the results for the bi-directionalbearing (see stator in figure 4(b)). In this case the LST parameters are Sp ¼ 0:614 and a ¼ 0:633. The clearances of the bi-directional partial-LST bearing are lower compared to these of the unidirectional bearing at the same load. At 460 N load the clearance for the 1500 rpm is 4.1 lm and for the 3000 rpm it is 6 lm. These values represent a reduction of clearance between 33 and 10% compared to the unidirectional case. However, as can be seen from figure 8 the performance of the partial-LST bi-directional bearing is still substantially better than that of the untextured bearing.The friction coefficient of partial-LST unidirectional and bi-directional bearings was compared with that of the untextured bearing in figures 9 and 10 for the two speeds of 1500 and 3000 rpm, respectively. As can be seen the friction coefficient of the two partial-LST bearings is very similar with slightly lower values in the case of the more efficient unidirectional bearing. The friction coefficient of the untextured bearing is much larger compared to that of the LST bearings. At 1500 rpm (figure 9) and the highest load of 460 N the friction coefficient of the untextured bearing is about 0.025 compared to about 0.01 for the LST bearings.At the lowest load of 160 N the values are about 0.06 for the untextured bearing and around 0.02 for the LST bearings. Hence, the friction values of the untextured bearing are between 2.5 and 3 times higher than the corresponding values for the partial-LST bearings over the entire load range. Similar results were obtained at the velocity of3000 rpm (figure 10) but the level of the friction coefficients is somewhat higherdue to the higher speed. The much higher friction of the untextured bearing is due to the much smaller clearances of this bearing (see figures 7 and 8) that result in higher viscous shear.Bearings fail for a number of reasons，but the most common are misapplication，contamination，improper lubricant，shipping or handling damage，and misalignment. The problem is often not difficult to diagnose because a failed bearing usually leaves telltale signs about what went wrong．However，while a postmortem yields good information，it is better to avoid the process altogether by specifying the bearing correctly in The first place．To do this，it is useful to review the manufacturers sizing guidelines and operating characteristics for the selected bearing.Equally critical is a study of requirements for noise, torque, and runout, as well as possible exposure to contaminants, hostile liquids, and temperature extremes. This can provide further clues as to whether a bearing is right for a job.1 Why bearings failAbout 40% of ball bearing failures are caused by contamination from dust, dirt, shavings, and corrosion. Contamination also causes torque and noise problems, and is often the result of improper handling or the application environment．Fortunately, a bearing failure caused by environment or handling contamination is preventable，and a simple visual examination can easily identify the cause．Conducting a postmortem il1ustrates what to look for on a failed or failing bearing．Then，understanding the mechanism behind the failure, such as brinelling or fatigue, helps eliminate the source of the problem.Brinelling is one type of bearing failure easily avoided by proper handing and assembly. It is characterized by indentations in the bearing raceway caused by shock loading－such as when a bearing is dropped-or incorrect assembly. Brinelling usually occurs when loads exceed the material yield point(350,000 psi in SAE 52100 chrome steel)．It may also be caused by improper assembly, Which places a load across the races．Raceway dents also produce noise，vibration，and increased torque.A similar defect is a pattern of elliptical dents caused by balls vibrating between raceways while the bearing is not turning．This problem is called false brinelling. It occurs on equipment in transit or that vibrates when not in operation. In addition, debris created by false brinelling acts like an abrasive, further contaminating the bearing. Unlike brinelling, false binelling is often indicated by a reddish color from fretting corrosion in the lubricant.False brinelling is prevented by eliminating vibration sources and keeping the bearing well lubricated. Isolation pads on the equipment or a separate foundation may be required to reduce environmental vibration. Also a light preload on the bearing helps keep the balls and raceway in tight contact. Preloading also helps prevent false brinelling during transit.Seizures can be caused by a lack of internal clearance, improper lubrication, orexcessive loading. Before seizing, excessive, friction and heat softens the bearing steel. Overheated bearings often change color，usually to blue-black or straw colored．Friction also causes stress in the retainer，which can break and hasten bearing failure．Premature material fatigue is caused by a high load or excessive preload．When these conditions are unavoidable，bearing life should be carefully calculated so that a maintenance scheme can be worked out．Another solution for fighting premature fatigue is changing material．When standard bearing materials，such as 440C or SAE 52100，do not guarantee sufficient life，specialty materials can be recommended. In addition，when the problem is traced back to excessive loading，a higher capacity bearing or different configuration may be used．Creep is less common than premature fatigue．In bearings．it is caused by excessive clearance between bore and shaft that allows the bore to rotate on the shaft．Creep can be expensive because it causes damage to other components in addition to the bearing．0ther more likely creep indicators are scratches，scuff marks，or discoloration to shaft and bore．To prevent creep damage，the bearing housing and shaft fittings should be visually checked．Misalignment is related to creep in that it is mounting related．If races are misaligned or cocked．The balls track in a noncircumferencial path．The problem is incorrect mounting or tolerancing，or insufficient squareness of the bearing mounting site．Misalignment of more than 1/4·can cause an early failure．Contaminated lubricant is often more difficult to detect than misalignment or creep．Contamination shows as premature wear．Solid contaminants become an abrasive in the lubricant．In addition。
机械设计与制造毕业设计论文中英文翻译外文翻译
毕业设计（论文）外文翻译如何延长轴承寿命摘要：自然界苛刻的工作条件会导致轴承的失效，但是如果遵循一些简单的规则，轴承正常运转的机会是能够被提高的。
在轴承的使用过程当中，过分的忽视会导致轴承的过热现象，也可能使轴承不能够再被使用，甚至完全的破坏。
但是一个被损坏的轴承，会留下它为什么被损坏的线索。
通过一些细致的侦察工作，我们可以采取行动来避免轴承的再次失效。
关键词：轴承失效寿命导致轴承失效的原因很多，但常见的是不正确的使用、污染、润滑剂使用不当、装卸或搬运时的损伤及安装误差等。
诊断失效的原因并不困难，因为根据轴承上留下的痕迹可以确定轴承失效的原因。
然而，当事后的调查分析提供出宝贵的信息时，最好首先通过正确地选定轴承来完全避免失效的发生。
为了做到这一点，再考察一下制造厂商的尺寸定位指南和所选轴承的使用特点是非常重要的。
1 轴承失效的原因在球轴承的失效中约有40%是由灰尘、脏物、碎屑的污染以及腐蚀造成的。
污染通常是由不正确的使用和不良的使用环境造成的，它还会引起扭矩和噪声的问题。
由环境和污染所产生的轴承失效是可以预防的，而且通过简单的肉眼观察是可以确定产生这类失效的原因。
通过失效后的分析可以得知对已经失效的或将要失效的轴承应该在哪些方面进行查看。
弄清诸如剥蚀和疲劳破坏一类失效的机理，有助于消除问题的根源。
只要使用和安装合理，轴承的剥蚀是容易避免的。
剥蚀的特征是在轴承圈滚道上留有由冲击载荷或不正确的安装产生的压痕。
剥蚀通常是在载荷超过材料屈服极限时发生的。
如果安装不正确从而使某一载荷横穿轴承圈也会产生剥蚀。
轴承圈上的压坑还会产生噪声、振动和附加扭矩。
类似的一种缺陷是当轴承不旋转时由于滚珠在轴承圈间振动而产生的椭圆形压痕。
这种破坏称为低荷振蚀。
这种破坏在运输中的设备和不工作时仍振动的设备中都会产生。
此外，低荷振蚀产生的碎屑的作用就象磨粒一样，会进一步损害轴承。
与剥蚀不同，低荷振蚀的特征通常是由于微振磨损腐蚀在润滑剂中会产生淡红色。
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外文文献的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。
实际上，摩擦从某种程度上说，存在于任何两个相接触并有相对运动趋势的部件之间。
而摩擦这个词，本身就意味着，两个或两个以上部件的阻止相对运动趋势。
在一个机器中，运动部件的摩擦是有害的，因为它降低了机械对能量的充分利用。
由它引起的热能是一种浪费的能量。
因为不能用它做任何事情。
还有，它还需要更大的动力来克服这种不断增大的摩擦。
热能是有破坏性的。
因为它产生了膨胀。
而膨胀可以使得轴承或滑动表面之间的配合更紧密。
如果因为膨胀导致了一个足够大的积压力，那么，这个轴承就可能会卡死或密封死。
另外，随着温度的升高，如果不是耐高温材料制造的轴承，就可能会损坏甚至融化。
在运动部件之间会发生很多摩擦，如1.启动摩擦2.滑动摩擦3.转动摩擦。
启动摩擦是两个固体之间产生的倾向于组织其相对运动趋势的摩擦。
当两个固体处于静止状态时，这两个零件表面的不平度倾向于相互嵌入，形成楔入作用，为了使这些部件“动”起来。
这些静止部件的凹谷和尖峰必须整理光滑，而且能相互抵消。
这两个表面之间越不光滑，由运动造成的启动摩擦（最大静摩擦力）就会越大。
因为，通常来说，在两个相互配合的部件之间，其表面不平度没有固定的图形。
一旦运动部件运动起来，便有了规律可循，滑动就可以实现这一点。
两个运动部件之间的摩擦就叫做滑动摩擦。
启动摩擦通常都稍大于滑动摩擦。
转动摩擦一般发生在转动部件和设备上，这些设备“抵触”极大的外作用力，当然这种外力会导致部件的变形和性能的改变。
在这种情况下，转动件的材料趋向于堆积并且强迫运动部件缓慢运动，这种改变就是通常所说的形变。
可以使分子运动。
当然，最终的结果是，这种额外的能量产生了热能，这是必需的。
因为它可以保证运动部件的运动和克服摩擦力。
由运动部件的表面不平度的楔入作用引起的摩擦可以被部分的克服，那就需要靠两表面之间的润滑。
但是，即使是非常光滑的两个表面之间也可能需要一种物质，这种物质就是通常所说的润滑剂，它可以提供一个比较好的、比较薄的油膜。
这个油膜使两个表面分离，并且组织运动部件的两个表面的相互潜入，以免产生热量使两表面膨胀，又引起更近的接触。
减小摩擦的另一种方式是用不同的材料制造轴承和转动零件。
可以拿黄铜轴承、铝合金和含油轴承合金做例子进行解释。
也就是说用软的或硬的金属组成表面。
含油轴承合金是软的。
这样，当轴承在油中浸泡过以后，因为毛细管的作用，将由带到轴承的各个表面。
这种类型的轴承把它的润滑剂带到应力最大的部位。
对运动部件润滑以减小摩擦，应力和热量，最常用的是油、脂、还有合成剂。
每一种润滑剂都有其各自不同的功能和用途。
两个运动部件之间的运动情况决定了润滑剂的类型的选择。
润滑剂的分布也决定了系统的选择。
在低速度运动的部件，一个油沟足以将所需要的数量的润滑剂送到相互运动的表面。
第二种通用的润滑方法是飞溅润滑系统，在每个周期内这个系统内一些零件经过润滑剂存储的位置，带起足够的润滑油，然后将其散布到所有的运动零件上。
这种系统用于草坪修剪机中发动机的曲轴箱，对曲轴、连杆和活塞等零件进行润滑。
在工业装置中，常用的有一种润滑系统是压力系统。
这种系统中，一个机器上的一个泵，可以将润滑剂带到所有的轴承表面。
并且以一种连续的固定的速度和数量。
关于润滑，还有许多其他的系统，针对各种类型的润滑剂，对不同类型的运动零件是有效的。
由于设备或装置的速度、压力和工作要求的提高，现代工业比以前任何时候都更注重选用适当的润滑剂。
尽管润滑的主要目的之一是为了减小摩擦力，任何可以控制两个滑动表面之间摩擦和磨损的物质，不管是液体还是固体或气体，都可以归类于润滑剂。
润滑的种类无润滑滑动。
经过精心处理的、去除了所有外来物质的金属在相互滑动时会粘附或熔接到一起。
当达不到这么高的纯净度时，吸附在表面的气体、水蒸气、氧化物和污染物就会降低摩擦力并减小粘附的趋势，但通常会产生严重的磨损，这种现象被称为“无润滑”摩擦或者叫做干摩擦。
流体膜润滑。
在滑动面之间引入一层流体膜，把滑动表面完全隔离开，就产生了流体膜润滑。
这种流体可能是有意引入的。
例如汽车主轴承中的润滑油；也可能是无意中引入的，例如在光滑的橡胶轮胎和潮湿的路面之间的水。
尽管流体通常是油、水和其他很多种类的液体，它可以是气体。
最常用的气体是空气。
为了把零件隔离开，润滑膜中的压力必须和作用在滑动面上的负荷保持平衡。
如果润滑膜中的压力是由外源提供的，这种系统称为流体静压润滑。
如果滑动表面之间的压力是由于滑动面本身的形状和运动所共同产生的，这种系统就称为流体动压力润滑。
边界润滑。
处于无润滑滑动和流体膜润滑之间的润滑被称为边界润滑。
它可以被定为这样一种润滑状态，在这种状态中，表面之间的摩擦力取决于表面的性质和润滑剂中的其他性质。
边界润滑包括大部分润滑现象，通常在机器的启动和停止时出现。
固体润滑。
当普通润滑剂没有足够的承受能力或者不能在温度极限下工作时，石墨和二硫化钼这一类固体润滑剂得到广泛应用。
但润滑剂不仅仅以脂肪、粉末和油脂这样一些为人们所熟悉的形态出现，在一些精密的机器中，金属也通常作为滑动面。
润滑剂的作用尽管润滑剂主要是用来控制摩擦和磨损的，它们能够而且通常也确实起到许多其他的作用，这些作用随其用途不同而不同，但通常相互之间是有关系的。
控制摩擦力。
滑动面之间润滑剂的数量和性质对所产生的摩擦力有很大的影响。
例如，不考虑热和磨损这些相关因素，只考虑两个油膜润滑表面见的摩擦力，它能比两个同样表面，但没有润滑时小200倍。
在流体润滑状况时，摩擦力与流体黏度成正比。
一些诸如石油衍生物这类润滑剂，可以有很多黏度，因此能够满足范围宽广的功能要求。
在边界润滑状态，润滑剂黏度对摩擦力的影响不象其化学性质的影响那么显著。
磨损控制。
磨蚀、腐蚀与固体和固体之间的接触就会造成磨损。
适当的润滑剂将能帮助克服上述提到的一些磨损现象。
润滑剂通过润滑膜来增加滑动面之间的距离，从而减轻磨料污染物和表面不平度造成的损伤，因此，减轻了磨损和由固体与固体之间接触造成的磨损。
控制温度。
润滑剂通过减小摩擦和将产生的热量带走来降低温度。
其效果取决于润滑剂的用量和外部冷却措施。
冷却剂的种类也会在较小的程度上影响表面的温度。
控制腐蚀。
润滑剂在控制表面腐蚀方面有双重作用。
当机器闲置不工作时，润滑剂起到防腐剂的作用。
当机器工作时，润滑剂通过给被润滑零件涂上一层可能含有添加剂，能使腐蚀性材料中和的保护膜来控制腐蚀。
润滑剂控制腐蚀的能力与润滑剂保留在金属表面的润滑膜的厚度和润滑剂的化学成分有直接的关系。
其他作用除了减小摩擦外，润滑剂还经常有其他的用途。
其中的一些用途如下所述。
传递动力。
润滑剂被广泛用来作为液压传动中的工作液体。
绝缘。
在象变压器和配电装置这些特殊用途中，具有很高介电常数的润滑剂起电绝缘材料的作用。
为了获得最高绝缘性能，润滑剂中不能含有任何杂质和水分。
减振。
在象减振器这样的能量传递装置中和在承受很高的间隙载荷的齿轮这样的机器零件的周围，润滑剂被作为减振液使用。
密封。
润滑脂通常还有一个特殊作用，就是形成密封层以防止润滑剂外泻和污染物进入。
润滑的目的就是为了，减小摩擦力，降低能量损耗，减少机器的热量产生。
热量就是因为表面的相互间的相对运动造成的。
润滑剂可以是任何一种物质，这样的物质被填充到发生相对运动的两个表面之间，实现这一目的。
大部分的润滑剂是液体，比如说，油，脂，合成剂等。
但它们有时也可能是固体，用在干轴承上，有的用在旋转基体的轴承上，或者也可能是气体，如空气等，它是用在空气轴承上。
在润滑剂和润滑表面之间这种化学的和物质的相互渗入作用，就是为了提供给机器一个良好的工作状态。
对润滑剂边界的理解，往往是比较硬的，而且是流动的、非常薄的一层帖附在被润滑的表面。
这些表面通常是要发生相对滑动。
有些人推断，按这种理解，液体的这种化学合成是十分重要的，它们提出了这样的词“边界润滑”，边界润滑是和流体润滑相对的另一种润滑。
关于润滑的五种不同的润滑形式主要有：（1）无润滑润滑剂。
（2）流体膜润滑。
（3）干润滑。
（4）边界润滑。
（5）固体润滑。
无润滑润滑剂是指轴承的工作表面被一种相对比较厚的液体润滑剂分隔开，于是阻止了金属表面的直接接触，这样得到的这种稳定性就可以用一种理论来解释：润滑液在外压力下工作的理论，尽管这只是一种可能。
但确实需要在任何时候都得提供的足够充分。
这种挤压力是运动表面本身施加给润滑剂而产生的，当然这仍然是一种可能。
这种由运动表面产生的挤压力产生了必要的压力来分隔工作表面来抵抗加在轴承上的载荷。
所以，这种润滑也可以被叫做液体润滑。
还有一种润滑方式，那是一种特别的润滑剂，它有时是空气或水，当加在轴承上的外载荷足够高时，它就会以一种比较厚的状态分隔开相互相对运动的工作表面。
所以，不象上面的那种润滑方式，并不需要两种工作表面一定发生相对运动。
第三种润滑方式是一种现象，这种现象是，一种润滑剂是用在发生相对转动的工作表面之间。
比如说齿轮或者是滚动轴承。
从数学上的解释就需要接触压力和流体机械的理论。
当轴承不得不在较高的温度下工作的时候，固体润滑剂例如合成物等，必须被使用，因为通常使用的润滑油在这种情况下都不能工作。
目前，在这方面的研究正在实施，为了寻找到合成轴承的材料，并且有低损耗和小的热量产生的性能。
在有的轴承上，摇杆旋转或在轴承上转动，相对运动就是滑动。
在一个自锁的轴承装置中，这种相对运动就是转动。
其他的装置也可能是旋转或滑动。
齿轮的齿啮合是转动与相对滑动的合成。
活塞是相对于刚体的滑动，所有的这些应用都需要润滑剂来减小摩擦，降低能耗，减少热量的产生。
在有些轴承的应用领域是不太成熟的。
有些有连接杆的轴承，比如说汽车发动机上的，必须在几千度高的高温下和各种不同性质的载荷下工作。
这种轴承用在汽轮发动设备上可以说是稳定性接近100%。
还有另一种极端的情况，在有些轴承有几千种应用，应对各种不同的载荷。
其他的辅助设施就相对不重要了。
需要的是一个简单的、容易安装的轴承。
需要很少的甚至是不需要润滑剂。
在这种情况下，有的轴承并不是最好的选择，因为成本和相近的公差。
最近在轴承材料上的研究已有了一定的突破。
随着对润滑的研究的知识的积累，设计出有良好工作状况和较高的稳定性的轴承已不是很遥远了。
附录2 外文文献外文文献Friction , Lubrication of Bearing In 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 stateof 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 movingsurfaces 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.Varieties 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 caseof 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 is referred 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 becomesless 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.Temperature 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 high dielectric 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 , andheating 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 thelubricant ,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 pooranswer 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.。