毕业设计机械类外文翻译

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机械自动化类毕业设计外文翻译--电子设计自动化

附录B 翻译原文Electronic design automation Keyword EDA; IC;VHDL language; FPGAPROCESS DESCRIPTIONThree obstacles in particular bedevil ic designers in this dawn of the system on a chip. The first is actually a shortfall-the hardware and software components of the design lack a unifying language. Then, as the number of logic gates per chip passes the million marks, verification of a design's correctness is fast becoming more arduous than doing the design itself. And finally, not only gate counts but chip frequencies also are climbing, so that getting a design to meet its timing requirements without too many design iterations is a receding goal.As is the wont of the electronic design automation (EDA) community, these concerns are being attacked by start-up companies led by a few individuals with big ideas and a little seed money. PARLEZ-VOUS SUPERLOG?A system on a chip comprises both circuitry and the software that runs on it. Such a device may contain an embedded processor core running a software modem. Most often, after the chip'sfunctionality is spelled out, usually on paper, the hardware com- potent is handed off to the circuit designers and the software is given to the pro- grammars, to meet up again at some later date.The part of the chips functionality that will end up as logic gates and transistors is writ- ten in a hardware design language-Virology or VHDL, while the part that will end up as software is most often described in the programming language C or C++. The use of these disparate languages hampers the ability to describe, model, and debug the circuitry of the IC and the software in a coherent fashion.It is time, many in the industry believe, for a new design language that can cope with both hardware and software from the initial design specification right through to final verification. Just such a new language has been developed by Co-Design Automation Inc., San Jose, Calif.Before launching such an ambitious enterprise, cofounders Simon Davidmann, who is also chief operating officer, and Peter Flake ruled out the usefulness of extending an existing language to meet system-on-chip needs. Among the candidates for extension were C, C++, Java, and Verilog.A design language should satisfy three requirements, maintained Davidmann. It should unify the design process. It should make designing more efficient. And it should evolve out of an existing methodology. None of the existing approaches filled the bill. So Davidmann and Flake set about developing new co-design language called Superlog.A natural starting point was a blend of Virology and C since "from an algorithm point of view, a lot of Virology is built on C," explained Davidmann. Then they spiced the blend with bits and pieces of VHDL and Java. From Virology and VHDL, Superlog has acquired the ability to describe hardware aspects of the design, such as sequential, combinatorial, and multivalued logic. From C and Java it inherits dynamic processes and other software constructs. Even functions like interfaces, protocols, and state machines, which till now have often been done on paper, can be described in the new language. To support legacy code written in a hardware description or programming language, Superlog allows both Virology and C modules to be imported and used directly.It is important for the language to be in the public domain, according to Davidmann. The company has already begun to work with various standards organizations to this end.Not to be overlooked is the need for a suite of design tools based on the language. Recently Co-Design identified a number of electronic design automation companies, among them Magma Design Automation, Sente, and Viewlogic, that will develop tools based on Superlog. Co-Design will also develop products for the front end of the design process.ARACE TO THE FINISHNot everyone is convinced that a new language is needed. SystemC, a modeling platform that extends the capabilities andadvantages of C/C++ into the hardware domain has been proposed as an alternative. Such large and powerful companies as Synopsys, Coware, Lucent Technologies, and Texas Instruments have banded together under the Open SystemC Initiative to promote their version of the next-generation design platform. To get SystemC off to a running start, the group offers a modeling platform for download off their Web site free of charge. Their hope is also to make their platform the de facto standard.The rationale for developing SystemC was straightforward, according to Joachim Kunkel, general manager and vice president of the System Level Design Business Unit at Synopsys. It was to have a standard language in which semiconductor vendors, IP vendors, and system houses could exchange system-level IP and executable specifications, and the electronic design automation industry could develop interoperable tools.Supporters of SystemC believe that the would-be standard has to be based on C++ because it allows capabilities to be added to it without leaving the language standard, Kunkel told JEEE Spectrum. Most software developers use C++ and many systems developers use C++ already to describe their systems at a behavioral level. But till now it has not been possible to describe hardware using the language.The developers of SystemC have solved that problem by defining new C++ class libraries and a simulation kcrne1 that bring to C++ all of the capabilities needed to describe hardware. "These new classes implement new functionality," explained Kunkel. "Forexample, bit vectors-strings of zeros and ones-and all the operations that you would do on them." The SystemC developers also provided a class of signed and unsigned numbers, the notion of a signal, and other concepts needed to model hardware.There are still some holes, however. For example, it is still not possible to synthesize a gate-level netlist from a SystcmC description. Rut synthesis tools for SysteniC would he a natural result of broad acceptance of the language within the user community, according to Kunkel.It remains to be seen whether SystemC or Superlog wins out in the end. Least desirable would be an outcome like the impasse between Virology and VHDL, in which both prevailed, forcing electronic design automation vendors to support both platforms in a wasteful duplication of effort.THE VERIFICATION NIGHTMAREIf today's complex ICs are tough to design, they are very much tougher to verify. A variety of tools are available, each with its pros and cons. Emulation translates a design into field-programmable gate arrays (FPGAs). Presumably, if the array works as planned, the final chip will also. The emulation platform also enables designers to try 0111 the software that will run on the ASIC.The approach, though, is slow. Typical emulation systems run at a few megahertz. "At roughly one million cycles per second, designers arc not getting cnough performance out of their emulation systems toverify or understand some of the things that are going on with video generation or high bandwidth communications," said John Gallagher, director of marketing for Synplicity Inc., Sunnyvale, Calif. They must process a large number of operations to ensure their functionality is correct, he added.The reason that emulation systems are so slow, according to Gallagher, is that they route the design through many FPGAs and many boards. Simplicity solution is to use a few high-end FPGAs having over one million gates running at 100 MHz. Typically, a million FPGA gates translates into 200 000 ASIC gates. Putting nine such chips on a board in a three-by-three array allows designers to represent up to 1.8million ASlC gates. And routing delays are greatly curtailed because each chip is no more than two hops away from any other chip in the array.The company% product, called Certify, is not intended to compete with reconfigurable emulation systems, which are very effective at debugging designs during the internal design process, explained Gallagher. Rather, it is a true prototype of the system, running at speeds that may approach the real thing.Certify handles three fundamental operations, said Gallagher. The first is partitioning, or breakings up the ASIC register transfer level (RTL) code into different FPGAs. It does synthesis, turning the RTL code into ASIC gates equivalent to the final ASIC gates. Then it does timing analysis. "We haven't just linked togeth er the different tools,” he explained. 'We have taka our synthesis algorithms, between thepartitioning capabilities, and laid the timing analysis across that."In addition to emulation, two complementary approaches to design verification are simulation and model checking, a type of formal verification. Simulation applies vectors to a software model of a design and checks to sec if the output has the correct value. The approach is straightforward, but is becoming increasingly tortuous as designs become more complicated and the number of possible test vectors mushrooms. So recently, electronic design automation companies have been turning to model checking to prove that designs are correctly done.The sticking point with model checking is its great difficulty of use. "It is not for most engineers," said Simon Napper, chief operating officer OF Innol-ogic Systems Inc., San Jose, Calif. "The usage model is very difficult-it checks properties. But the designer isn't familiar with what P property is-he is used to simulation and static timing."As a remedy, InnoLogic developed a symbolic simulation tool, which blends simulation and formal verification. It is a Virology simulator except instead of sending Is and Os through the logic, the too1 propagates symbol or symbols plus binary values.The user gains improved functional coverage dong with much faster verification.To illustrate, to completely verify a fourbit adder would require 256 binary vectors-and take 256 simulation cycles. With symbols, it takes just one cycle.Just as with formal verification, there are limits to the complexity ofthe circuits that symbolic simulation can completely verily. Both have trouble with multipliers, for example. "A model checker will grind and grind and never produce a result," explained Napper. "But in our tool we take some symbol inputs and switch them to binary values, that reduces the job from a 32- to a 16-bit multiplier. And we report to the user that we were able to verify the upper the operands."InnoLogic has announced two Versifies of symbolic simulation. ESI'-XV verifies designs written in Virology. EXP-CV is meant for custom designs and memory blocks.THE TIME IS RIGHTThough the design of ICs with semiconductor geometries below 0.25 pm face challenges throughout development, some of the biggest hurdles occur during physical design, when the gates are placed on the chip and the interconnects are routed between them Problems occur here for a number of reasons. First, the capacitance, resistance, and inductance of the interconnects cannot be ignored, as they were in older, larger technologies. Crosstalk between interconnects; now closer together, must also be controlled. Several iterations through synthesis and placement may be necessary to achieve the required timing, if it can be accomplished at all.The solution proposed by Monterey Design Systems Inc., Sunnyvale, Calif., is called global design technology. This proprietary computing approach simultaneously explores, analyzes, and optimizes all aspects of the physical design. The tint productcontaining the technology is Dolphin, which was announced in April of last year. Dolphin simultaneously places and router each gate and flip-flop using the results or the analysis and maintaining all specified constraints. (Most place- and-route tools sequentially analyze the layout for each type of constraint.) It performs timing and logic optimization for every placement move.Timing closure is top priority for developers of the Blast Fusion physical design system from Magma Design Automations., Cupertino, Calif. Its methodology, called FixedTiming, brings timing within specified limits without iterating between synthesis and physical design .Basically, he approach fixes timing first, then adjusts cell sizes to achieve the timing requirements. Varying the cell sizes always he tool to supply the right drive strength or the load.EDA ON THE WEBAs established electronic design automation companies try to sort out how to utilize the internet in their product Inks, smaller, more agile companies and start-ups arc coining up with innovative products and services, mainly in the areas or design management. A pioneer in this area is Synchronicity Inc., a virtual company headquartered in Marlboro, Mass. Synchronicity is now being joined by other companies seeking to use the internet to advantage.The concern of , Milpitas, Calif a provider of Web-based engineering tools 'for; design automation, is the extraction of useful information about ICs, chip sets, and boards from suppliers'Web sites.The issue, according to Michael Bitzko, president of the company, is that designers of products based on there components need to be able to obtain information about them quickly and route it to their engineering, manufacturing, and procurement departments as quickly as possible. "In a nutshell,” said Bitzko, "people used to take weeks to get data sheets. Then along cane the Web and PDF-formatted documents. But in order to create, ray, schematic symbols and footprints fur printed circuit boards, information from PDF documents must often be reentered-a costly and time-consuming process when time to infarct is a concern.'s products are based on the electronic component interchange (ECIX) standard developed by EDA standards organization SI, Austin, Texas, and on the Extensible Markup Language (XML), that allows the creation or Web-bask documents having (more functionality than with the conventional Hypertext Markup Language (H TM1.). The company’s products include QuickData Server, a parametric search engine for electronic component information, and Quickdata Miner, which transform information contained in PDF data sheets into a usable form.The mission or Genedax Inc., Portland, Ore. is to use the Web to increase designed ability to create and manage large, complex designs, to iron design ICLISC, and to improve access to intellectual property. The company plans to announce a product in the first quarter or the year. John Ott, vice president of sales and marketing,told Sprctmni that its products will be based on the operating systems and browsers developed by Microsott Corp., Redmond, Wash. Also, the company supports a collaborative Web site, that shows what the technology can do. The site includes a search engine based on AltaVista technology that searches the Web sites of companies related to design auto illation. Ott elaborated, "We also have a free Internet locator server that lets people use Netmeeting a Microsoft product for remote sharing of computer desktops] and a Web board where you can post questions and get answers."Other aspects of electronic design on the Webs have been slower in taking off than design and information management. But Transim Corp also bared in Portland, Ore, has taken a big step toward Web-based design tools. Its product, Websim, is an interface between a Web browser and Simples, the company’s power-supply simulator. Websim allows designers, using Simplis, to simulate designs over the Internet. So rather than poring over data sheets and looking at ranges of values, designers can see actual waveforms, explained Ncls Gahbert, Transim president and chief executive officer.Transim is working with suppliers to set up component models so that designers can log on to the supplies Web rite, select parts for their power supply, enter setup or test conditions, and run the simulation on line. Users need nothing more than a Web browser. The simulation is run on Transim's "ranch" of six strivers from Sun Microsystems.The company has teamed up with National Semiconductor Corp, Santa Clara, Calif., to provide this service for National's customers. The cost is on a per-use basis and is a minimal US $10.附录C 翻译中文电子设计自动化关键字电子设计自动化；集成电路；VHDL语言；现场可编程门阵列在这个片上系统开始出现的时候，有三个问题一直困扰着集成电路设计者。

机械毕业设计英文外文翻译402驱动桥和差速器 (2)

附录附录ADrive axle/differentialAll vehicles have some type of drive axle/differential assembly incorporated into the driveline. Whether it is front, rear or four wheel drive, differentials are necessary for the smooth application of engine power to the road.PowerflowThe drive axle must transmit power through a 90° angle. The flow of power in conventional front engine/rear wheel drive vehicles moves from the engine to the drive axle in approximately a straight line. However, at the drive axle, the power must be turned at right angles (from the line of the driveshaft) and directed to the drive wheels.This is accomplished by a pinion drive gear, which turns a circular ring gear. The ring gear is attached to a differential housing, containing a set of smaller gears that are splined to the inner end of each axle shaft. As the housing is rotated, the internal differential gears turn the axle shafts, which are also attached to the drive wheels.Fig 1 Drive axleRear-wheel driveRear-wheel-drive vehicles are mostly trucks, very large sedans and many sports car and coupe models. The typical rear wheel drive vehicle uses a front mounted engine and transmission assemblies with a driveshaft coupling the transmission to the rear drive axle. Drive in through the layout of the bridge, the bridge drive shaft arranged vertically in the same vertical plane, and not the drive axle shaft, respectively, in their own sub-actuator with a direct connection, but the actuator is located at the front or the back of the adjacent shaftof the two bridges is arranged in series. Vehicle before and after the two ends of the driving force of the drive axle, is the sub-actuator and the transmission through the middle of the bridge. The advantage is not onlya reduction of the number of drive shaft, and raise the driving axle of the common parts of each other, and to simplify the structure, reduces the volume and quality.Fig 2 Rear-wheel-drive axleSome vehicles do not follow this typical example. Such as the older Porsche or Volkswagen vehicles which were rear engine, rear drive. These vehicles use a rear mounted transaxle with halfshafts connected to the drive wheels. Also, some vehicles were produced with a front engine, rear transaxle setup with a driveshaft connecting the engine to the transaxle, and halfshafts linking the transaxle to the drive wheels.Differential operationIn order to remove the wheel around in the kinematics due to the lack of co-ordination about the wheel diameter arising from a different or the same rolling radius of wheel travel required, inter-wheel motor vehicles are equipped with about differential, the latter to ensure that the car driver Bridge on both sides of the wheel when in range with a trip to the characteristics of rotating at different speeds to meet the requirements of the vehicle kinematics.Fig 3 Principle of differentialThe accompanying illustration has been provided to help understand how this occurs.1.The drive pinion, which is turned by the driveshaft, turns the ring gear.2.The ring gear, which is attached to the differential case, turns the case.3.The pinion shaft, located in a bore in the differential case, is at right angles to the axle shafts and turns with the case.4.The differential pinion (drive) gears are mounted on the pinion shaft and rotate with the shaft .5.Differential side gears (driven gears) are meshed with the pinion gears and turn with the differential housing and ring gear as a unit.6.The side gears are splined to the inner ends of the axle shafts and rotate the shafts as the housing turns.7.When both wheels have equal traction, the pinion gears do not rotate on the pinion shaft, since the input force of the pinion gears is divided equally between the two side gears.8.When it is necessary to turn a corner, the differential gearing becomes effective and allows the axle shafts to rotate at different speeds .Open-wheel differential on each general use the same amount of torque. To determine the size of the wheel torque to bear two factors:equipment and friction. In dry conditions, when a lot of friction, the wheel bearing torque by engine size and gear restrictions are hours in the friction (such as driving on ice), is restricted to a maximum torque, so that vehicles will not spin round. So even if the car can produce more torque, but also need to have sufficient traction to transfer torque to the ground. If you increase the throttle after the wheels slip, it will only make the wheels spin faster.Fig 4 Conventional differential Limited-slip and locking differential operationFig 5 Limited-slip differentialDifferential settlement of a car in the uneven road surface and steeringwheel-driven speed at about the different requirements; but is followed by the existence of differential in the side car wheel skid can not be effective when the power transmission, that is, the wheel slip can not produce the driving force, rather than spin the wheel and does not have enough torque. Good non-slip differential settlement of the car wheels skid on the side of the power transmission when the issue, that is, locking differential, so that no longer serve a useful differential right and left sides of the wheel can be the same torque.Limited-slip and locking differential operation can be divided into two major categories：(1) mandatory locking type in ordinary differential locking enforcement agencies to increase, when the side of the wheel skid occurs, the driver can be electric, pneumatic or mechanical means to manipulate the locking body meshing sets of DIP Shell will be with the axle differential lock into one, thus the temporary loss of differential role. Relatively simple structure in this way, but it must be operated by the driver, and good roads to stop locking and restore the role of differential.(2) self-locking differential installed in the oil viscosity or friction clutch coupling, when the side of the wheel skid occurs when both sides of the axle speed difference there, coupling or clutch friction resistance on the automatic, to make certain the other side of the wheel drive torque and the car continued to travel. When there is no speed difference on both sides of the wheel, the frictional resistance disappeared, the role of automatic restoration of differentials. More complicated structure in this way, but do not require drivers to operate. Has been increasingly applied in the car. About non-slip differential, notonly used for the differential between the wheels, but also for all-wheel drive vehicle inter-axle differential/.Gear ratioThe drive axle of a vehicle is said to have a certain axle ratio. This number (usually a whole number and a decimal fraction) is actually a comparison of the number of gear teeth on the ring gear and the pinion gear. For example, a 4.11 rear means that theoretically, there are 4.11 teeth on the ring gear for each tooth on the pinion gear or, put another way, the driveshaft must turn 4.11 times to turn the wheels once. The role of the final drive is to reduce the speed from the drive shaft, thereby increasing the torque. Lord of the reduction ratio reducer, a driving force for car performance and fuel economy have a greater impact. In general, the more reduction ratio the greater the acceleration and climbing ability, and relatively poor fuel economy. However, if it is too large, it can not play the full power of the engine to achieve the proper speed. The main reduction ratio is more Smaller ，the speed is higher, fuel economy is better, but the acceleration and climbing ability will be poor.附录B驱动桥和差速器所有的汽车都装有不同类型的驱动桥和差速器来驱动汽车行驶。

(完整版)_毕业设计(机械)外文翻译_

Visualization of PLC Programs using XMLM. Bani Younis and G. FreyJuniorprofessorship Agentenbased AutomationUniversity of KaiserslautemP. 0. Box 3049, D-67653 Kaiserslautem, Germany Abstract - Due to the growing complexity of PLC programs there is an increasing interest in the application of formal methods in this area. Formal methods allow rigid proving of system properties in verification and validation. One way to apply formal methods is to utilize a formal design approach in PLC programming. However, for existing software that approach that can start from a given PLC program. Therefore, formalization of PLC programs is a topic of current research. The paper outlines a re-engineering approach based on the formalization of PLC programs. The transformation into a vendor independent format and the visualization of the structure of PLC programs is identified as an important intermediate step in this process. It is shown be used for the formalization and visualization of an existing PLC program.I. INTRODUCTIONProgrammable Logic Controllers (PLCs) are a special type of computers that are used in industrial and safety critical applications. The purpose of a PLC is to control a particular process, or a collection of processes, by producing electrical control signals in response to electrical process- related inputs signals. The systems controlled by PLCs vary tremendously, with applications in manufacturing, chemical process control, machining, transportation, power distribution, and many otherfields. Automation applications can range in complexity from a simple panel to operate the lights and motorized window shades in a conference room to completely automated manufacturing lines.With the widening of their application ，PLC programs are being subject to increased complexity and the compliance of limited development time as well as the reusability of existing software or PLC modules requires a formal approach to be developed [I]. Ensuring the and validation procedures as well as analysis and simulation of existing systems to be carried out [2]. One of the important fields for the formalization of PLC programs that growing up in recent time is Reverse-engineering [3]. Reverse Engineering is a process of evaluating something to understand order to duplicate or enhance it. While the reuse of PLC codes is being established as a tool for combating the complexity of PLC programs, Reverse Engineering is supposed to receive increased importance in the coming years especially if exiting of existing PLC programs is an important intermediate step of Reverse Engineering. The paper provides an approach towards the visualization of PLC programs using XML which is an important approach for the orientation and better understanding for engineers working with PLC programs.The paper is structured as follows. First, a short introduction to PLCs and the corresponding programming techniques according to the IEC standard is given. In Section Ⅲan approach for Re-engineering based on formalization of PLC programs is introduced. The transformation of the PLC code into a vendor independent format is identified as an important first step in this process. XML and corresponding technologies such asXSL and XSLT that can be used in this transformation are presented in Section IV. Section V presents the application of XML for the visualization of PLC programs and illustrates the approach with an example. The final Section summarizes the results and gives an outlook on future work in this ongoing project.ⅡPLC AND IEC 61131Since its inception in the early …70s the PLC received increasing attention due to its success in fulfilling the objective of replacing , research and development, mainly for Control Engineering.IEC 61 131 is the first real endeavour to standardize PLC programming languages for industrial automation. In I993 the International Electrotechnical Commission [4] published the IEC 61131 Intemational Standard for Programmable Controllers. Before the standardization PLC programming languages were being developed as proprietary programming languages usable to PLCs of a special vendor. But in order to enhance compatibility, openness and interoperability among different products as well as to promote the development of tools and methodologies with respect to a fixed set of notations the IEC 61131 standard evolved. The third part of this standard defines a suit of five programming languages:Instruction List (IL) is a low-level textual language with a structure similar to assembler. Originated in Europe IL is considered to be the PLC language in which all other IEC61 131-3 languages can be translated.Ladder Diagram (LO) is a graphical language that the USA. LDs conform to a programming style borrowed from electronic and electricalcircuits for implementing control logics.Structured Text (STJ is a very powerful Block Diagram (FBD) is a graphical language and it is very common to the process industry. In this language controllers are modelled as signal and data flows through function blocks. FBD transforms textual programming into connecting function blocks and thus improves modularity and software reuse.Sequential Function Chart (SFC) is a graphical language. SFC elements are defined for structuring the organization of programmable controller programs.One problem with IEC 61 131-3 is that there is no standardized format for the project information in a PLC programming tool. At the moment there are only vendor specific formats. This is also one reason for the restriction of formalization approaches to single programs or algorithms. However, recently the PLC users‟ organization PLCopen (see .org) started a Technical Committee to define an XML based format for projects according to IEC. This new format will ease the access of formalization tools to all relevant information of a PLC project.Ⅲ. RE-ENGINEERING APPROACHThe presented approach towards re-engineering (cf. Fig.1) is based upon the conception that XML can be used as a medium in which PLC codes will be transformed.This transformation offers the advantage of obtaining avendor independent specification code. (Even if the PLCopen succeeds in defining a standardized format for PLC applications, there will remain a lot of existing programs that do not conform to this standard.)Based on this code a step-wise transformation to a formal model (automata) is planned. This model can then be used for analysis, simulation, formal verification and validation, and finally for the re-implementation of the optimized algorithm on the same or another PLC.Since re-engineering of complete programs will, in most cases, be only a semi-automatic process, intermediate visualization of the code is an important point. At different stages of the process different aspects of the code andor formal model a way that a designer can guide the further work. XML with its powerful visualization and transformation tools is an ideal tool for solving this task.IV. XML AS A TOOL FOR VISUALIZATIONXML (extensible Markup Language) is a simple and flexible meta-language, i.e，a language for describing other languages. Tailored by the World Wide Web Consortium (W3C) as a dialect of SGML [S], XML removes two constraints which were a single, inflexible document type (HTML) which was being much abused for tasks it was never designed for on one side; and the complexity of full SGML, whose syntax allows many powerful but the other side.While HTML describes across platforms and applications. XML can be tailored to describe virtually any kind of information in a form that the recipient of the information can use in a variety of ways. It is specifically designed to support information exchange between systems that use fundamentally different forms of data representation, as for example between CAD and scheduling applications.Using XML with its powerful parsers and inherent robustness interms of syntactic and semantic grammar is more advantageous than the conventional method of using a lexical analyzer and a validating parser (cf. Fig. 2, [7]).The conventional method of analysis of program code requires a scanner (lexical analyser) which generates a set of terminal symbols (tokens) followed by a parser thatchecks the grammatical structure of the code and generates an object net. In the object net the internal structure of the program is represented by identified objects and the relations between them. Both the scanner and the parser to be used in this method are document oriented which implies that analysis of different types of documents requires rewriting the generated code for the scanner and the parser. An example of an application of this method can be found in [8].The most promising aspect of using XML instead is that XML and its complementary applications for transformations are standardized so as to provide maximum flexibility to its user.The XML based method is advantageous, since the lexical specification is an invariant component of XML; therefore the well-formedness is independent from the respective individual application.Hence, an XML-Parser also can transfer well-shaped XML documents in an abstract representation called Document Object Model (DOM) without using a grammar. DOM is an application programming interface (APII) for valid HTML and well-formed XML documents. It defines the logical structure of documents and the way a document is accessed and manipulated. In the DOM specification, the term "document" is used in abroad sense increasingly. XML is used as a way of representing many different kind of information that may be stored in diverse systems, and much of this would traditionally be seen as data rather than as documents. Nevertheless, XML presents this data as documents, and the DOM can be used to manage this data［5］.XSLT, the transformation language for XML is capable of transforming XML not only to another XML or HTML but to many other user-friendly formats. Before the advent of XSLT, the transformation of XML to any other format was only possible through custom applications developed in a procedural language such as C++, Visual Basic or, Java. This procedure lacked the generality with respect to the structural variation of XML documents. Capitalizing on the concept that the custom applications for the transformations are all very similar, XSLT evolved as a two steps. In the first step, it performs a structural transformation so as to convert the XML into a structure that reflects the desired output. The second stage is formatting the new structure into the required format, such as HTML or PDF (cf. Fig. 3 ). The most important advantage of this transformation is that it allows a simple and easily-conceivable representation of the document or data structure embedded inside the well-structured but HTML is chosen as the format of the transformed produce it is possible to use the extensive ability of HTML to produce an easily-conceivable and attractive visualization of a program.Every XML document syntax and vocabulary. Therefore, in addition to being well-formed, the XML document needs to conform to a set of rules. According to W3C recommendations this set of rules (DTD) or an XMLSchema. The rules defined in a DTD or an XML Schema state the proposed. The W3C XML Schema language replicates the essential functionality of DTDs, and adds a number of features: the use of XML instance syntax rather than an ad , clear relationships between schemas and namespaces, a systematic distinction between element types and data types, and a single-inheritance form of type derivation. In other words schemas offer a richer and more powerful way of describing information than what is possible with DTDs. Fig. 4 shows the XML technologies discussed above and the connection between them.V. AN APPROACH FOR THE VISUALIZATION OFPLC PROGRAMSA. OverviewSince Instruction List (IL) is the most commonly used PLC language in Europe, the presented approach is based on this language. The proprietary IL dialect Siemens STEP 5 and the standardized version according to IEC are considered.The generation of XML documents showing different aspects of a PLC program is realized in the following three steps (cf. Fig. 5):1.Transformation of the PLC program to an XML document2.Validation of the XML against the XML Schema which sets the syntax of the XML3.Identification of the Instruction elements of the transformed XML according to the instruction set of the source PLCThese three steps are discussed in sub-sections B to D respectively. Sub-section E explains the visualization of the different XMLs obtainedduring the preceding steps.Throughout this Section an example is used to illustrate the presented concepts. Fig. 6 shows a PLC code written in Instruction List Siemens S5. The PLC code is written in atabular form where each row element is either a delimited list consisting of address, label, instruction, operand and description or a comment.Kommentar :AutorErstellt :15.07.2003 Geaendert am: B1B:ONETZWERK 1 EMPFANGEN SLAVE 3 VON MASTERNAME :EMPE'MAST0005 :U M98.7 ABFRAGE OB EMPFANG MOEGLICH00060007 :SPB= MOOl00080009 :A DB140 EMPFANGSFACH IST DB 140OOOA :L KF+20 LAENGE DES DATENPAKETSoooc :T DLOOOOD :L KF+O ZIELNUMMER O=MASTEROOOF :T DRO00100011 :UNM98.7 FANGEN WIEDER ERLAUBEN0012 :S M98.70013 MOOl :NOP 000140015 :BE BAUSTEIN ENDEFig. 6 A PLC program written in Siemens S5 Instruction ListB. Conversion of a PLC Program inio a well-formed XMLGiven a PLC program in ASCII format and in a tabular structure with separate columns for addresses, labels, instructions, operands and descriptions delimited by whitespaces, XSLT can convert it into a well-formed XML document. The XML document obtained through this transformation is a of the PLC code of Fig. 6. The XML document is structured in a which the root element is the IL Code Block representing the whole PLC code. Each of the rows of the PLC code is contained within a corresponding ILRow element which is M e r smtctured into child elements.Note: The structure chosen for the XML representation of IL-Code is oriented at the working proposal of the PLCopen.C. XML Validation against the XML SchemaThe XML obtained as a result of the previous processing can be validated using a validating parser that confirms that the XML document in addition to being well-formed conforms to the set of syntactic rules defined in context of the PLC programming language.D. rdenhpcation of instructionsThis step in the process of visualization of PLC programs using XML ensures that the XML document to be used for visualization contains only valid instructions.XSLT can be used to transform the well-formed and valid Xh4L to another XML which as a result of identification oninstructions additional attribute appended to the instruction tags. This attribute notifies whether the instruction is a valid instruction of the concerned instruction set. This transformation procedure is also capable of attaching attributes to the instruction tags that declares a classification of the instructions into predefined classes.The instruction identification of the transformed XML proofs the semantic of the XML in accordance with the operation types of the PLC programming language.In the example of this section, (cf. Fig. 8), the new XML contains additional attributes which classify the instructions according to the type of operation it represents. The STEPS instructions are categorized into eleven different types of operations e.g. logical, jump, load or transfer operation assignment, etc.<?xml version="l.O" encOding="ISO" ?><ILCodeBlock><ILRow>(Instruction instructionId='Logical Operation")U<Instruction><ILROW>-.<ILRow><Instruction instructionId="Jump Operation">SPB-<Instruction><Instruction instructionId=" special Opera tion"> BE<Instruction><ILROW><ILRow>Fig. 8 A new transformed XML showing only the inslructions and the corresponding instruction ID<ILCodeBlack>E. Visualization of XMLBoth of the XML documents generated above can be transformed into HTML or other readable documents with the ingenious XSL can be designed so as to produce an HTML which can convey the logical and other features of the PLC program in an easily conceivable form. Moreover, the DOM structure embedded in the XML (cf. Fig. 9), also enables the user to navigate through the PLC programs in an easy way.For the example the visualization is done in HTML. This visualization is done for the transformed XML after the validation of it's syntax as a table where the child elements of the ILRow are the columns of this table.The XML after the instruction identification is transformed using the XSL, where the instruction and the instruction Id, obtained after extracting the XML according to the type of operations are visualized in a table containing two columns (Instruction, Instruction Id) in HTML.The HTML structures suggested be visualized, but they give a very easy practical option for the user's grasp of the PLC code.Fig. IO shows the same PLC code as shown in Fig. 4 as a HTML document converted &om the XML document shown in Fig. 7 using XSL. This visualization enables a better understanding of the PLC program. Fig.11 shows the special visualization of instruction ids given in the XML of Fig. 6.VI. CONCLUSIONS AND OUTLOOKRe-engineering of PLC programs needs a formal approach to be developed. In this paper one way to solve this task is introduced. Based on a given PLC program written in Instruction List a step-wise transformation to a formal representation is proposed. Since this process will not be fully automatic, the need for flexible visualization of intermediate steps is derived. XML is presented as a flexible, standardized means to serve as data format for the description of the PLC code. The corresponding technology of XSL transformations and the Document Object Model are presented as tools for the variety of customized visualization tasks during the re-engineering process.Based on the XML description of PLC programs further transformations will be applied to finally derive a completely formalized description of the original PLC code. This will be in the form of a finite automaton. During this process it is planned to identify common IL structures and formalize them via a library.Gaining the Benefit of the XML Metadata Interchange (XMI) as an open industry standard that applies XML to abstract systems such as UML and referring to the classification of the instructions of IL into the eleven categories mentioned above. We can extract UML classes from this classification, as it resembles the action semantics of UML.VII. AKNOWLDGMENTWe would like to express gratitude to the “StiAung Rheinland-Pfalz fir Innovation” for sponsoring our work under project number 616.VIII. REFERENCES1. L. Baresi, M. Mauri, A. Monti, and M. Pezze, “PLCTools: Design, Formal Validation, a nd Code Generation for Programmable Controllers”, in. IEEEConference on Systems, Man, and Cybernefics (SMCZOOO), Nashville, USA, Oct. 2000, pp. 2437-2442.2. G. Frey and L. Litz, “Formal methods in PLC programming”, in IEEE Con on Systems, Man and Cybernetics(SMC’ZOOO), Nashville, USA, Oct. 2000, pp..3. M. Bani Younis and G. Frey, “Formalization of Existing PLC Programs:A Survey.“, in CESA 2003, Lille (France), Paper No. S2-R July 2003.4. International Electrotechnical Commission, IEC International Standard Programmable Controllers, Part 3, Programming Languages, 1993.5. World Wide Web Consortium: Steuerungssojiware.Ph.D. thesis, University of Kaiserslautern, Germany,Institute for Production-Automation, 1999.8. M. Kay, XSLT - Programmer’s Referenc e. ISBN Wrox Press Ltd2001可视化的PLC程序使用XML米巴尼尤尼斯和G.弗雷摘要:由于P LC程序日益复杂,在PLC应用方面有越来越多的兴趣爱好者。

江苏大学机械毕业设计外文翻译

江苏大学机械毕业设计电磁阀外文翻译附录Ⅰ：Magnetoelastic Torque Sensor Utilizing a Thermal Sprayed Sense-Element for Automotive Transmission ApplicationsBrian D. KilmartinSiemens VDO Automotive Corporation ABSTRACTA Magnetoelastic based Non-Contacting, Non-Compliant Torque Sensor is being developed by Siemens VDO for automotive transmission applications. Such a sensor would benefit the automotive industry by providing the feedback needed for precise computer control of transmission gear shifting under a wide range of road conditions and would also facilitate cross-platform usage of a common transmission unit.Siemens VDO has prototyped transmission torque sensors operating on the principle of Inverse- magnetostriction, also referred to as the Inverse-Joule Effect and the Villari Effect. Magnetostriction, first documented in the mid 1800’s, is a structural property of matter that defines a m aterial’s dimensional changes as a result of exposure to a magnetic field. Magnetostriction is caused when the atoms that constitute a material reorient in order to align their magnetic moments with an external magnetic field. This effect is quantified for a specific material by its saturation magnetostriction constant, which is a value that describes a material’s maximum change in length per unit length.Inverse-magnetostriction, conversely, defines changes in a material’s magnetic properties in response to applied mechanical forces. Material that is highly magnetostrictive and elastic in nature is referred to as being magnetoelastic. The premise of the Siemens VDO torque sensor design is that a magnetoelastic material can be bonded to a cylindrical shaft and magnetized in its mechanical quiescent state to create a sense- element. While under torque, principle tensile and compressive stress vectors in the form of counter- spiraling, mutually orthogonal helices develop in the shaft and are conveyed to the magnetoelastic sense-element giving rise to a measurable magnetic field change. The magnetic field deviation that arises from the magnetoelastic sense-element is directly proportional to the magnitude of the imposed torque. In effect, the magnetic field is modulated by torque. A sensitive magnetometer then translates the field strength into an analog voltage signal, thereby completing the torque-to-voltage transducer function.Critical to the success of the Siemens VDO torque sensor design is an intimate attachment of the sense- element to the torque-bearing member. Inconsistencies in the boundary between the sense-element and the torque-bearing member will result in aberrant coupling of stresses into the sense-element manifesting in performance degradation. Boundary inconsistencies can include such imperfections as voids, contaminates, lateral shearing, and localized zonesof stress pre-load. Such inhomogeneities may be inherent to an attachment method itself or may subsequently be caused by systemically rendered malformations.Thermal spray, the process where metal particles are deposited onto a substrate to form a coating, was used to address the issue of securely affixing magnetic material to a torque-bearing member. In addition to achieving the prerequisite of an intimate and secure bond, the thermal spray process can be regulated such that the deposited magnetic material is pre-loaded with the internal stresses needed to invoke the inverse- magnetostriction effect.Summarizing, the passive nature of the magnetic sense- element provides an intrinsically simple kernel for the Siemens VDO torque sensor that makes for a highly reliable and stable design. The thermal spray process adds robustness to the mechanical aspect by permitting torque excursions to an unprecedented ±2000% of full scale (per prototype validation testing of certain constructs) without the need for ancillary torque limiting protection devices. Furthermore, accuracy, repeatability, stability, low hysteresis, rotational position indifference, low cost and amenability to the high-volume manufacturing needs of the automotive marketplace are all attributes of this torque sensing technique. When coupled with a magnetometer that is grounded in well- established fluxgate technology, the resultant sensor is inherently dependable and can potentially establish a new standard for torque measuring sensors.INTRODUCTIONAs is well known, automotive transmissions are designed to alter the power transfer ratio between the engine and the drive wheels effectively optimizing engine loading. The engine thereby runs in a narrow and efficient operating band even though the vehicle travels over a wide range of speeds. For automatic transmissions, shift valves select the gear ratio based generally on the throttle position, engine vacuum and the output shaft governor valve state. With the advent of electronic sensors and computerized engine controllers, transmission shift functions have been migrating towards closed-loop operation under software processing control. Along with this progression came the realization that the transmission output torque would provide a valuable feedback parameter for shift and traction control algorithms. The measurement of output torque, however, proved elusive due to the extremely harsh operating conditions. One particular SUV application under consideration required 1% accuracy in measurements of roughly 2700 Nm with possible torque excursion of 4700 Nm; all while exposed to temperature extremes -45 to +160 o C.One method for measuring torque is to examine the physical stresses that develop in a shaft when it is subjected to an end-to-end twisting force. The principle stresses are compressive and tensile in nature and develop along the two counter-spiraling, mutually orthogonal 45 o helices. They are defined by the equation :t = Tr / JWhere T is the torque applied to the shaft, r is the shaft radius and J is the polar moment of inertia.Setting p r4/ 2 = J for a solid cylindrical shaft and r = d/2 yields:t = 16T / p dOnce again, T is the torque applied to the shaft and d is the shaft diameter.Furthermore, the degree of twist experienced by the shaft for a given torque is given by2: q = 32(LT) / (p d4G)Where L is the length of the shaft, T is the applied toque, d is the diameter of the shaft and G is the modulus of rigidity of the shaft. The modulus of rigidity defines the level of elasticity of the shaft material, thus, a lower G value would manifest in a shaft with a higher degree of twist for any given applied torque.Torque induced stresses that occur in the shaft material are transferred into an affixed magnetic coating and give rise to measurable changes in its surrounding magnetic field that are directly proportional to the magnitude of the applied torque; with the polarity of the magnetic field, i.e., north or south, governed by the direction of the applied torque. In essence, this is the premise of torque sensing by means of inverse magnetostriction.TORQUE SENSOR EMBODIMENTTo effectively invoke the inverse-magnetostriction effect, the magnetic material must be correctly pre-loaded with stress anisotropy in its quiescent state. In the case of a cylindrically shaped magnetic element, the anisotropic forces must be circumferential (i.e., tangential) in nature and can be either compressive or tensile –depending on the polarity or sign of the material’s saturation magnetostriction constant. Achieving a homogenous pre-load throughout the magnetic material is crucial if the sensor is to accurately interpret torque regardless of its rotational position within a stationary magnetometer.POSITIVE MAGNETOELASTIC DEVICESEarlier efforts to create such a torque sensing element relied on a sense element made of material with a positive saturation magnetostriction constant. This embodiment was realized with a ring-shaped magnetoelastic element made from 18% nickel-iron alloy that intrinsically requires tensile circumferential pre- loading 3 . Such a pre-load was achieved by pressing the ring onto a tapered area of the base shaft – effectively stretching it. The effect of tensile stress on the magnetic hysteresis behavior is shown in Figure 1 where the remnant inductance, B r , nearly triples. The “easy-axes” of the magnetic domains align circumferentially due to the anisotropy defined by the principal tensile stress vector. When magnetically biased, the system in effect operates as a circumferentially shorted magnet with B approaching B r and H approaching zero.NEGATIVE MAGNETOELASTIC DEVICESTo advance the state of the art, Siemens VDO Automotive has opted for a magnetoelastic element witha negative saturation magnetostriction constant. In this case, the alloy is very high in nickel content exhibiting a saturation magnetostriction, l s , in the range of -3e-5 dl/l and requires the stress pre-load to be tangentially compressive in nature. To achieve this embodiment, the magn etoelastic material that constitutes the sense element is “deposited” onto the base shaft using a high- velocity-oxygen-fuel (HVOF) thermal spray process. The coating thickness is only 0.5mm with an axial length of 25mm. The sense element material is endowed with compressive stress by means of precise control of the thermal spray process parameters. This proprietary procedure transforms a deposition process that normally confers isotropic material properties into one that renders the requisite stress anisotropy.Prototype FabricationMagnetoelastic ElementThe specification for the shaft requires the measurement of torque levels of 2700 Nm with no deleterious effects following exposures of up to 4700 Nm. Operating temperature is -45 o C to 160 o C.By c onverting from the earlier torque sensor “pressed-on ring” concept to one based on a magnetoelastic material with a negative saturation magnetostriction constant, l s , the design is advanced in several respects. Primarily, its resiliency against stress/corrosion cracking is enhanced by 1) the inherent insusceptibility of high nickel content alloys towards corrosives and 2) by the lower porosity of material in compression. This is in distinct contrast with the high iron content ring placed in tension which is vulnerable to fissuring, material creep and stress corrosion cracking which can, over time, relieve the necessary anisotropic forces causing performancedegradation.An important consequence of using the thermal spray technology is the intimate bond provided between the deposited magnetoelastic element and the base shaft. By using a thermal spray process, the boundary whereby torque induced stresses are transferred is free of such imperfections as voids, galled or furrowed material and localized stress gradients that are all characteristically associated with the pressed-on ring technique. These imperfections can induce aberrations in the magnetic field shape thereby imparting torque measurement errors relative to the rotational position of the shaft with respect to a stationary magnetometer. Furthermore, the strong bond at the interface effectively eliminates the slippage commonly associated with the interference fit of a pressed-on ring during extreme torque exposures. Any movement at this interface will manifest as a biasing of material stresses causing a zero-shift measurement error. This is not a concern when the magnetoelastic element is deposited using an HVOF thermal spray gun. Torque excursions to an unprecedented ±2000% of full scale have been successfully applied directly to prototype sensors without ancillary torque limiting protection devices.In addition, depositing the magnetoelastic element onto a rotating shaft provides an inherently mechanically balanced assembly that imposes no angular velocity (RPM) or angular acceleration limits on the system.Other thermal spray technology attributes are its amenability to high volume manufacturing environments, the robustness of the process insuring consistent reproducibility, and an overall reduction in fabrication steps –such as the elimination of machining procedures to mass-produce rings, cutting operations for precisely matching tapers on the shaft and ring, and pressing operations to install rings onto shafts.Magnetic Field ShapingContributions from the mechanical mounting tolerances of system components (e.g., bearings and bushings) can manifest as a misalignment between the centroid centerlines of the magnetometer and the magnetoelastic element. Once calibrated, any displacement in the positional relationship between these two components will alter the system’s transfer function, possibly causing the overall error to exceed specification. The sharply focused nature of the magnetic field radially emanating from the magnetoelastic element during the application of torque (see Figure 3) accentuates this effect. This error can be minimized by shaping the physical structure of the magnetoelastic element resulting in a contouring of the magnetic field to a more favorable shape. As shown in Figure 4, the magnetic field is made to be less pronounced with an hourglass shaped magneto elastic element and sensitivity to misalignment is, thus, reduced. In this example, the magneto elastic element is contoured such that the air gap between the magneto elastic element and the magnetometer is reduced when axial displacement between their centroid centerlines occurs. The expected reduction in magnetic signal strength caused by this displacement is thus compensated by the air gap reduction.Shafts can be fabricated with a variety of contoured surface adaptations and the thermal sprayed magnetoelastic element’s shape will expectedly follow suit. As is evident, a pressed-on ring manifestation of the magnetoelastic element would be incompatible with this technique. Various contours are being considered for further reducing the sensitivity to misalignment and for improving other performance parameters such as magnetic field strength and hysteresis.Cylindrical Shaft Shown with Superimposed Associated Magnetic Field (i.e., Radially Directed Flux Density)Contoured Shaft (Hourglass Shape) Shown with Superimposed Associated Magnetic Field (i.e., Radially Directed Flux Density)In Figures 3 and 4, the spatial image of the shaft is mapped using a laser displacement system and the superimposed magnetic field is mapped in 3-space with a hall cell.MagnetometerRounding out the torque sensor hardware complement is a non-contacting magnetometer that translates the magnetic signal emitted by the shaft’s sense element into an electrical signal that can be read by system-level devices. Coupling the torque signal to some interim conditioning electronics magnetically is an attractive op tion due to its “non-contacting” attribute. A signal transference scheme capable of spanning an air gap is advantageous sinceit requires no slip rings, brushes or commutators that can be affected by wear, vibration, corrosion or contaminants.The fundamental magnetometer embodiment, shown in Figure 5, is circular with the shaft passing through its center. The magnetometer encompasses the magnetoelastic element of the shaft and the shaft is allowed to freely rotate within the fixed magnetometer. Power and the output signal pass through the magnetometer’s wiring harness.Transmission Torque Sensor MagnetometerThe magnetometer actually performs several functions beyond measuring a magnetic field’s strength. These functions include magnetic signal conditioning, electrical signal conditioning, implementation of self-diagnostics, and the attenuation of magnetic and electromagnetic noise sources.The magnetic detection method chosen for the torque sensor is fluxgate magnetometry, also known as saturable-core magnetometry. This is a well-established technology that has been in use since the early 1900’s. Fluxgate magnetometers are capable of measuring small magnetic field of strengths down to about 10 -4 A/m (or 10 -6 Oe) with a high level of stability. This performance is roughly three orders of magnitude better than that achieved by Hall Effect devices. Although many fluxgate designs use separate drive and pickup coils, the torque sensor magnetometer was designed to use a single coil for both functions.Magnetic signal conditioning is accomplished by use of flux guides integral to the magnetometer. These flux guides amplify the magnetic signal radiating from the shaft’s sense element prior to detection by the fluxgates thereby improving the signal-to-noise ratio. The flux guides provide additional signal conditioning by integrating inhomogeneities in the magnetic signal relative to the shaft rotational position that might otherwise be misinterpreted as torque variations. The flux guide configuration is shown in Figure 6 and a magnetic simulation of the resulting field concentration is shown in Figure 7.Flux guides surrounding magnetoelastic elementAxial view of magnetic simulation with flux guide material’s relative DC permeability set to 50,000 (e.g., HyMu “80”)To further improve the magnetometer’s immunity to stray signals present in the ambient, common-mode rejection schemes are employed in the design of both the electronic and magnetic circuits. For example, wherever possible, differential circuitry was used in theelectronic design in order to negate common-mode noise. This practice was carried over to the magnetic design through the use of symmetrically shaped flux guides and symmetrically placed fluxgates that cancel common- mode magnetic signals that originate outside the system.Finally, to augment the electrical and magnetic common- mode rejection strategies, EMI and magnetic shielding practices were incorporated into the design to further improve the signal-to-noise ratio. Stray magnetic and electro-magnetic signals found in the ambient are prevented from reaching the fluxgates and the shaft’s magnetic torque-sensing element through the use of shielding material that encompasses these critical components.The functional diagram of Figure 8 depicts the concept of the magnetometer by showing a simplified version of the circuitry with extraneous components removed for additional clarity. An application specific integrated circuit (ASIC) contains all the circuitry necessary to perform the indicated functions.Magnetometer Functional DiagramSummarizing, the multi-function, fluxgate based magnetometer design provides the optimal platform for detecting the modulated magnetic field that emanates from the shaft’s torque-sensing magnetic element. By coupling time-proven fluxgate technology with an innovative flux guide configuration and with sophisticated electronic circuitry, the resultant magnetometer is durable, accurate, and stable and comprehensively achieves the design goals dictated by the application.CONCLUSIONThe latest developments in the magnetoelastic torque sensor that are presented here advance the current state of the technology by addressing many obstacles that have delayed itsacceptance by the automotive industry. Thermal spray deposition of the magnetoelastic element has resolved problems that have plagued earlier versions of the magnetoelastic torque sensor’s active element. The lack of integrity of the shaft/magnetoelastic element interface, stress-corrosion cracking, long term stability, inhomogeneity of magnetic properties and manufacturing processes that run counter to high volume production, are no longer hindering the introduction of magnetoelastic torque sensors into the automotive marketplace. With design goals clearly defined and an aggressive development program invariably progressing, the prospect of an automotive, magnetoelastic based non-compliant torque sensor is now more readily attainable.ACKNOWLEDGMENTSI would like to acknowledge the efforts of Ivan Garshelis who pioneered this approach to torque sensing and who had the unwavering vision to recognize this technology’s potential; and Carl Gandarillas whose scientific and analytical investigative approach has explicated much of the mystery associated with thermal sprayed magnetics. I would also like to express my gratitude to the torque sensor development team at Siemens VDO Automotive for their dedication and the extra effort that they put forth; and to Siemens VDO Automotive management for having the courage to invest in a new technology and the patience to see it through.REFERENCES1. Raymond J. Roark and Warren C. Young, Formulas for Stress and Strain, 5 th Edition, McGraw-Hill; Chapter 9, Torsion2. Stephen H.Crandall and Norman C. Dahl, An Introduction to the Mechanics of Solids, McGraw-Hill; Chapter 6, Torsion3. Ivan J. Garshelis, Magnetoelastic Devices, Inc., IEEE Transaction On Magnetics ; 0018-9464/92 V ol. 28, No. 5 September 5, 1992ADDITIONAL SOURCES1. Richard L. Carlin, Magnetochemistry; Springer-Verlag2. Rollin J. Parker, Advances In Permanent Magnetism; John Wiley & Sons3. Etienne du Tremolet de Lachhesserie, Magnetostriction Theory and Applications of Magnetostriction; CRC Press4. Richard M. Bozorth, Ferromagnetism; IEEE Press附录Ⅱ：磁力矩传感器利用一个热喷涂感知元件在汽车变速器中的应用转载自：2003年发动机电子控制布赖恩D.基尔马丁西门子威迪欧汽车电子公司摘要一个非接触式的，非兼容扭矩的传感器是由西门子VDO正在开发应用于汽车传动之中。

机械专业毕业设计外文翻译1

本科毕业设计（本科毕业论文）外文文献及译文文献、资料题目：High-rise Tower Crane designed文献、资料来源：期刊（著作、网络等）文献、资料发表（出版）日期：2000.3.25院（部）：机电工程学院专业：机电工程及自动化High-rise Tower Crane designed under Turbulent Winds At present, construction of tower cranes is an important transport operations lifting equipment, tower crane accident the people's livelihood, major hazards, and is currently a large number of tower crane drivers although there are job permits, due to the lack of means to monitor and review the actual work of a serious violation . Strengthen the inspection and assessment is very important. Tower crane tipping the cause of the accident can be divided into two aspects: on the one hand, as a result of the management of tower cranes in place, illegal operation, illegal overloading inclined cable-stayed suspended widespread phenomenon; Second, because of the tower crane safety can not be found in time For example,Took place in the tower crane foundation tilt, micro-cracks appear critical weld, bolts loosening the case of failure to make timely inspection, maintenance, resulting in the continued use of tower cranes in the process of further deterioration of the potential defect, eventually leading to the tower crane tipping. The current limit of tower crane and the black box and can not be found to connect slewing tower and high-strength bolts loosening tightened after the phenomenon is not timely, not tower verticality of the axis line of the lateral-line real-time measurement, do not have to fight the anti-rotation vehicles, lifting bodies plummeted Meng Fang, hook hoists inclined cable is a timely reminder and record of the function, the wind can not be contained in the state of suspended operation to prevent tipping on the necessary tips on site there is a general phenomenon of the overloaded overturning of the whole security risks can not be accurately given a reminder and so on, all of which the lease on the tower crane, use, management problems,Through the use of tower crane anti-tipping monitor to be resolved. Tower crane anti-tipping Monitor is a new high-tech security monitoring equipment, and its principle for the use of machine vision technology and image processing technology to achieve the measurement of the tilt tower, tower crane on the work of state or non-working state of a variety of reasons angle of the tower caused by the critical state to achieve the alarm, prompt drivers to stop illegal operation, a computer chip at the same time on the work of the state of tower crane be recorded. Tower crane at least 1 day overload condition occurs, a maximum number of days to reach 23 overloading, the driver to operate the process of playing the anti-car, stop hanging urgency, such as cable-stayed suspended oblique phenomenon often, after verification and education, to avoid the possible occurrence of fatal accidents. Wind conditions in the anti-tipping is particularly important, tower cranes sometimes connected with the pin hole and pin do not meet design requirements, to connect high-strength bolts are not loose in time after the tightening of the phenomenon, through timely maintenance in time after the tightening of the phenomenon, through timely maintenance and remedial measures to ensure that the safe and reliable construction progress. Reduced lateral line tower vertical axis measuring the number of degrees,Observation tower angle driver to go to work and organize the data once a month to ensure that the lateral body axis vertical line to meet the requirements, do not have to every time and professionals must be completed by Theodolite tower vertical axismeasuring the lateral line, simplified the management link. Data logging function to ensure that responsibility for the accident that the scientific nature to improve the management of data records for the tower crane tower crane life prediction and diagnosis of steel structures intact state data provides a basis for scientific management and proactive prevention of possible accidents, the most important thing is, if the joint use of the black box can be easily and realistically meet the current provisions of the country's related industries. Tower crane safety management at the scene of great importance occurred in the construction process should be to repair damaged steel, usually have to do a good job in the steel tower crane maintenance work and found that damage to steel structures, we must rule out potential causes of accidents, to ensure safety in production carried out smoothly. Tower crane in the building construction has become essential to the construction of mechanical equipment, tower crane at the construction site in the management of safety in production is extremely important. A long time, people in the maintenance of tower crane, only to drive attention to the conservation and electrical equipment at the expense of inspection and repair of steel structures, to bring all kinds of construction accidents.Conclusion: The tower crane anti-tipping trial monitor to eliminate potential causes of accidents to provide accurate and timely information, the tower crane to ensure the smooth development of the leasing business, the decision is correct, and should further strengthen and standardize the use of the environment (including new staff training and development of data processing system, etc.).The first construction cranes were probably invented by the Ancient Greeks and were powered by men or beasts of burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of human treadwheels, permitting the lifting of heavier weights. In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction – some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron and steel took over with the coming of the Industrial Revolution.For many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first 'mechanical' power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still utilised where the provision of power would be uneconomic.Cranes exist in an enormous variety of forms – each tailored to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes,used for constructing high buildings, and the largest floating cranes, used to build oil rigs and salvage sunken ships.This article also covers lifting machines that do not strictly fit the above definition of a crane, but are generally known as cranes, such as stacker cranes and loader cranes.The crane for lifting heavy loads was invented by the Ancient Greeks in the late 6th century BC. The archaeological record shows that no later than c.515 BC distinctive cuttings for both lifting tongs and lewis irons begin to appear on stone blocks of Greek temples. Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity, they are regarded by archaeologists as the positive evidence required for the existence of the crane.The introduction of the winch and pulley hoist soon lead to a widespread replacement of ramps as the main means of vertical motion. For the next two hundred years, Greek building sites witnessed a sharp drop in the weights handled, as the new lifting technique made the use of several smaller stones more practical than of fewer larger ones. In contrast to the archaic period with its tendency to ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned in favour of using several column drums.Although the exact circumstances of the shift from the ramp to the crane technology remain unclear, it has been argued that the volatile social and political conditions of Greece were more suitable to the employment of small, professional construction teams than of large bodies of unskilled labour, making the crane more preferable to the Greek polis than the more labour-intensive ramp which had been the norm in the autocratic societies of Egypt or Assyria.The first unequivocal literary evidence for the existence of the compound pulley system appears in the Mechanical Problems (Mech. 18, 853a32-853b13) attributed to Aristotle (384-322 BC), but perhaps composed at a slightly later date. Around the same time, block sizes at Greek temples began to match their archaic predecessors again, indicating that the more sophisticated compound pulley must have found its way to Greek construction sites by then.During the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire. The earliest reference to a treadwheel (magna rota) reappears in archival literature in France about 1225, followed by an illuminated depiction in a manuscript of probably also French origin dating to 1240. In navigation, the earliest uses of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Brugge in 1288 and Hamburg in 1291, while in England the treadwheel is not recorded before 1331.Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. Typical areas of application were harbors, mines, and, in particular, building sites where the treadwheel crane played a pivotal role in the construction of the lofty Gothic cathedrals. Nevertheless, both archival and pictorial sources of the time suggest that newly introduced machines like treadwheels or wheelbarrows did not completely replace more labor-intensive methods like ladders, hods and handbarrows. Rather, old and new machinery continued to coexist on medieval construction sites and harbors.Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes, cranks and by the 15th century also by windlasses shaped like a ship's wheel. To smooth out irregularities of impulse and get over 'dead-spots' in the lifting process flywheels are known to be in use as early as 1123.The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Alternatively, the medieval treadwheel may represent a deliberate reinvention of its Roman counterpart drawn from Vitruvius' De architectura which was available in many monastic libraries. Its reintroduction may have been inspired, as well, by the observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities.In contrast to modern cranes, medieval cranes and hoists - much like their counterparts in Greece and Rome - were primarily capable of a vertical lift, and not used to move loads for a considerable distance horizontally as well. Accordingly, lifting work was organized at the workplace in a different way than today. In building construction, for example, it is assumed that the crane lifted the stone blocks either from the bottom directly into place, or from a place opposite the centre of the wall from where it could deliver the blocks for two teams working at each end of the wall. Additionally, the crane master who usually gave orders at the treadwheel workers from outside the crane was able to manipulate the movement laterally by a small rope attached to the load. Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340. While ashlar blocks were directly lifted by sling, lewis or devil's clamp (German Teufelskralle), other objects were placed before in containers like pallets, baskets, wooden boxes or barrels.It is noteworthy that medieval cranes rarely featured ratchets or brakes to forestall the load from running backward.[25] This curious absence is explained by the high friction force exercised by medieval treadwheels which normally prevented the wheel from accelerating beyond control.目前，塔式起重机是建筑工程进行起重运输作业的重要设备，塔机事故关系国计民生、危害重大，而目前众多的塔机司机虽然有上岗证，由于缺少监督和复核手段，实际工作中违规严重。

机械工程专业毕业设计外文翻译

英文原文名Lthes中文译名车床10/ 1中文译文：车床车床主要是为了进行车外圆、车端面和镗孔等项工作而设计的机床。

车削很少在其他种类的机床上进行，而且任何一种其他机床都不能像车床那样方便地进行车削加工。

由于车床还可以用来钻孔和铰孔，车床的多功能性可以使工件在一次安装中完成几种加工。

因此，在生产中使用的各种车床比任何其他种类的机床都多。

车床的基本部件有：床身、主轴箱组件、尾座组件、溜板组件、丝杠和光杠。

床身是车床的基础件。

它能常是由经过充分正火或时效处理的灰铸铁或者球墨铁制成。

它是一个坚固的刚性框架，所有其他基本部件都安装在床身上。

通常在床身上有内外两组平行的导轨。

有些制造厂对全部四条导轨都采用导轨尖朝上的三角形导轨（即山形导轨），而有的制造厂则在一组中或者两组中都采用一个三角形导轨和一个矩形导轨。

导轨要经过精密加工以保证其直线度精度。

为了抵抗磨损和擦伤，大多数现代机床的导轨是经过表面淬硬的，但是在操作时还应该小心，以避免损伤导轨。

导轨上的任何误差，常常意味着整个机床的精度遭到破坏。

主轴箱安装在内侧导轨的固定位置上，一般在床身的左端。

它提供动力，并可使工件在各种速度下回转。

它基本上由一个安装在精密轴承中的空心主轴和一系列变速齿轮(类似于卡车变速箱)所组成。

通过变速齿轮，主轴可以在许多种转速下旋转。

大多数车床有8~12种转速，一般按等比级数排列。

而且在现代机床上只需扳动2~4个手柄，就能得到全部转速。

一种正在不断增长的趋势是通过电气的或者机械的装置进行无级变速。

由于机床的精度在很大程度上取决于主轴，因此，主轴的结构尺寸较大，通常安装在预紧后的重型圆锥滚子轴承或球轴承中。

主轴中有一个贯穿全长的通孔，长棒料可以通过该孔送料。

主轴孔的大小是车床的一个重要尺寸，因此当工件必须通过主轴孔供料时，它确定了能够加工的棒料毛坯的最大尺寸。

数字控制的机器比人工操纵的机器精度更高、生产出零件的一致性更好、生产速度更快、而且长期的工艺装备成本更低。

机械专业毕业设计外文翻译--机械传动系统介绍

Transmission System introducedThe important position of the wheel gear and shaft can’t falter in traditional machine and modern machines. The wheel gear and shafts mainly install the direction that delivers the dint at the principal axis box. The passing to process to make them can is divided into many model numbers, used for many situations respectively. so we must be the multilayers to the understanding of the wheel gear and shaft in many ways.In the force analysis of spur gears, the forces are assumed to act in a single plane. We shall study gears in which the forces have three dimensions. The reason for this, in the case of helical gears, is that the teeth are not parallel to the axis of rotation. And in the case of bevel gears, the rotational axes are not parallel to each other. There are also other reasons, as we shall learn.Helical gears are used to transmit motion between parallel shafts. The helix angle is the same on each gear, but one gear must have a right-hand helix and the other a left-hand helix. The shape of the tooth is an involute helicoid. If a piece of paper cut in the shape of a parallelogram is wrapped around a cylinder, the angular edge of the paper becomes a helix. If we unwind this paper, each point on the angular edge generates an involute curve. The surface obtained when every point on the edge generates an involute is called an involute helicoids.The initial contact of spur-gear teeth is a line extending all the way across the face of the tooth. The initial contact of helical gear teeth is a point, which changes into a line as line as the teeth come into more engagement. In spur gears the line of contact is parallel to the axis of the rotation; in helical gears, the line is diagonal across the face of the tooth. It is this gradual of the teeth and the smooth transfer of load from one tooth to another, which give helical gears the ability to transmit heavy loads at high speeds. Helical gears subject the shaft bearings to both radial and thrust loads. When the thrust loads become high or are objectionable for other reasons, it may be desirable to use double helical gears. A double helical gear (herringbone) is equivalent to two helical gears of opposite hand, mounted side by side on the same shaft. They develop opposite thrust reactions and thus cancel out the thrust load. When two or more single helical gears are mounted on the same shaft, the hand of the gears should be selected so as to produce the minimum thrust load.Crossed-helical, or spiral, gears are those in which the shaft centerlines are neither parallel nor interesting. The teeth of crossed-helical fears have point contact with each other which changes to line contact as the gears wear in. for this reason they will carry out very small loads and are mainly for instrumental applications, and are definitely not recommended for use in the transmission of power. There is on difference between a crossed helical gear and a helical gear until they are mounted in mesh with each other. They are manufactured in the same way. A pair of meshed crossed helical gears usually have the same hand; that is, a right-hand driver goes with a right-hand driven. In the design of crossed-helical gears, the minimum sliding velocity is obtained when the helix angle are equal. However, when the helix angle are not equal, the gear with the larger helix angle should be used as the driver if both gears have the same hand.Worm gears are similar to crossed helical gears. The pinion or worm has a small number of teeth, usually one to four, and since they completely wrap around the pitch cylinder they are called threads. Its mating gear is called a worm gear, which is not a true helical gear. A worm and worm gear are used to provide a high angular-velocity reduction between nonintersecting shafts which are usually at right angle. The worm gear is not a helical gear because its face is made concave to fit the curvature of the worm in order to provide line contact instead of point contact. However, a disadvantage of worm gearing is the high sliding velocities across the teeth, the same as with crossed helical gears.Worm gearing are either single or double enveloping. A single-enveloping gearing is one in which the gear wraps around or partially encloses the worm. A gearing in which each element partially encloses the other is, of course, a double-enveloping worm gearing. The important difference between the two is that area contact exists between the teeth of double-enveloping gears while only line contact between those of single-enveloping gears. The worm and worm gear of a set have the same hand of helix as for crossed helical gears, but the helix angles are usually quite different. The helix angle on the worm is generally quite large, and that on the gear very small. Because of this, it is usual to specify the lead angle on the worm, which is the complement of the worm helix angle, and the helix angle on the gear; the two angles ate equal for a 90-deg. Shaft angle.When gears are to be used to transmit motion between intersecting shaft, some ofbevel gear is required. Although bevel gear are usually made for a shaft angle of 90 deg. They may be produced for almost any shaft angle. The teeth may be cast, milled, or generated. Only the generated teeth may be classed as accurate. In a typical bevel gear mounting, one of the gear is often mounted outboard of the bearing this means that shaft deflection can be more pronounced and have a greater effect in the contact of teeth. Another difficulty, which occurs in predicting the stress in bevel-gear teeth, is the fact the teeth are tapered.Straight bevel gears are easy to design and simple to manufacture and give very good results in service if they are mounted accurately and positively. As in the case of squrgears, however, they become noisy at higher values of the pitch-line velocity. In these cases it is often good design practice to go to the spiral bevel gear, which is the bevel counterpart of the helical gear. As in the case of helical gears, spiral bevel gears give a much smoother tooth action than straight bevel gears, and hence are useful where high speed are encountered.It is frequently desirable, as in the case of automotive differential applications, to have gearing similar to bevel gears but with the shaft offset Such gears are called hypoid gears because their pitch surfaces are hyperboloids of revolution The tooth action between such gears is a combination of rolling and has much in common with that of worm gears.A shaft is a rotating or stationary member usually of circular cross section, having mounted upon it such elementsas gears pulleys flywheels, cranks sprockets and other power-transmission elements Shaft may be subjected to bending tension compression or torsional loads acting singly or in combination with one another .When they are combined one may expect to find both static and fatigue strength to be important design considerations since a single shaft may be subjected to static stresses completely reversed, and repeated stresses, all acting at the same timeThe word “shaft” covers numerous wariations, such as axles and spindles. Anaxle is a shaft, wither stationary or rotating nor subjected to torsion load. Ashirt rotating shaft is often called a spindle.When either the lateral or the tosional deflection of shaft must be held to close limits, the shaft must be sized on the basis of deflection before analyzing the stresses The reasonfor this is that if the shift is made stiff enough so that the deflection is not too large, it is probable that the resulting stresses will be safe. But by no means should the designer assume that they are within acceptable limits. Whenever possible the power-transmission elements such as gears or pullets, should be located close to the supporting bearings. This reduces the bending moment, and hence the deflection and bending stress.Although the von Mises-Hencky-Goodman method is difficult to use in design of shaft, it probably come closest to predicting actual failure. Thus it is a good way of checking a shaft that has already been designed or of discovering why a particular shaft that has already been designed or of discovering why a particular shaft has failed in service. Furthermore, there are a considerable number of shaft-design problems in which the dimension are pretty well limited by other considerations, such as rigidity, and it is only necessary for the designer to discover something about the fillet sizes, heat-treatment, and surface finish and whether or not shot peening is necessary in order to achieve the required life and reliability.Because of the similarity of their functions, clutches and brakes are treated together. In a simplified dynamic representation of a friction clutch, or brake, two inertias I1and I2 traveling at the respective angular velocities W1 and W2, one of which may be zero in the case of brake, are to be brought to the same speed by engaging the clutch or brake. Slippage occurs because the two elements are running at different speeds and energy is dissipated during actuation, resulting in a temperature rise. In analyzing the performance of these devices we shall be interested in the actuating force, the torque transmitted, the energy loss and the temperature rise. The torque transmitted is related to the actuating force, the coefficient of friction, and the geometry of the clutch or brake. This is problem in static, which will have to be studied separately for each geometric configuration. However, temperature rise is related to energy loss and can be studied without regard to the type of brake or clutch because the geometry of interest is the hear-dissipating surfaces. The various types of clutches and brakes may be classified as fallows:Rim type with internally expanding shoesRim type with internally contracting shoesBand typeDisk or axial typeCone typeMiscellaneous typeThe analysis of all type of friction clutches and brakes use the same general procedure. The following step are necessary:1. Assume or determine the distribution of pressure on the frictionalsurfaces.2. Find a relation between the maximum pressure and the pressure at any point3. apply the condition of statical equilibrium to find (a) the actuating force, (b) the torque, and (c) the support reactions.Miscellaneous clutches include several type, such as the positive-contact clutches, overload-release clutches, overrunning clutches, magnetic fluid clutches, and others.A positive-contact clutch consists of a shift lever and two jaws. The greatest differences between the various types of positive clutches are concerned with the design of the jaws. To provide a longer period of time for shift action during engagement, the jaws may be ratchet-shaped, or gear-tooth-shaped. Sometimes a great many teeth or jaws re used, and they may be cut either circumferentially, so that they engage by cylindrical mating, or on the faces of the mating elements.Although positive clutches are not used to the extent the frictional-contact type, they do have important applications where synchronous operation is required.Devices such as linear driver or motor-operated screw drivers must run to definite limit and then come to a stop. An over load-release rype of clutch is required for these applications. These clutches are usually spring-loaded so as to release at a predetermined toque. The clicking sound which is heard when the overload point is reached is considered to be a desirable signal.An overrunning clutch or coupling permits the driven member of a machine to “freewheel” or “overrun” because the driver is stopped or because another source of power increase the speed of the driven. This type of clutch usually uses rollers or balls mounted between an outer sleeve and an inner member having flats machined around the periphery. Driving action is obtained by wedding the rollers between the sleeve and the flats. The clutch is therefore equivalent to a pawl and ratchet with an infinite number of teeth.Magnetic fluid clutch or brake is a relatively new development which has two parallel magnetic plates. Between these plates is a lubricated magnetic powder mixture. An electromagnetic coil is inserted somewhere in the magnetic circuit. Bu varying the excitation to this coil, the shearing strength of the magnetic fluid mixture may be accurately controlled. Thus any condition from a full slip to a frozen lockup may be obtained.机械传动系统介绍在传统机械和现代机械中齿轮和轴的重要地位是不可动摇的。

机械类毕业设计外文翻译---轴承的摩擦与润滑

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 industrypays 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 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 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 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 , 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 lubric ation 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.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。

机械类毕业设计外文翻译--龙门式起重机金属材料的疲劳强度预测

英文文章：Fatigue life prediction of the metalwork ofa travelling gantry craneV.A. KopnovAbstractIntrinsic fatigue curves are applied to a fatigue life prediction problem of the metalwork of a traveling gantry crane. A crane, used in the forest industry, was studied in working conditions at a log yard, an strain measurements were made. For the calculations of the number of loading cycles, the rain flow cycle counting technique is used. The operations of a sample of such cranes were observed for a year for the average number of operation cycles to be obtained. The fatigue failure analysis has shown that failures some elements are systematic in nature and cannot be explained by random causes.卯1999 Elsevier Science Ltd. All rights reserved.Key words: Cranes; Fatigue assessment; Strain gauging1. IntroductionFatigue failures of elements of the metalwork of traveling gantry cranes LT62B are observed frequently in operation. Failures as fatigue cracks initiate and propagate in welded joints of the crane bridge and supports in three-four years. Such cranes are used in the forest industry at log yards for transferring full-length and sawn logs to road trains, having a load-fitting capacity of 32 tons. More than 1000 cranes of this type work at the enterprises of the Russian forest industry. The problem was stated to find the weakest elements limiting the cranes' fives, predict their fatigue behavior, and give recommendations to the manufacturers for enhancing the fives of the cranes.2. Analysis of the crane operationFor the analysis, a traveling gantry crane LT62B installed at log yard in the Yekaterinburg region was chosen. The crane serves two saw mills, creates a log store, and transfers logs to or out of road trains. A road passes along the log store. The saw mills are installed so that the reception sites are under the crane span. A schematic view of the crane is shown in Fig. 1.1350-6307/99/$一see front matter 1999 Elsevier Science Ltd. All rights reserved.PII: S 1 3 5 0一6307(98) 00041一7A series of assumptions may be made after examining the work of cranes:·if the monthly removal of logs from the forest exceeds the processing rate, i.e. there is a creation of a logstore, the crane expects work, being above the centre of a formed pile with the grab lowered on the pile stack;·when processing exceeds the log removal from the forest, the crane expects work above an operational pile close to the saw mill with the grab lowered on the pile;·the store of logs varies; the height of the piles is considered to be a maximum;·the store variation takes place from the side opposite to the saw mill;·the total volume of a processed load is on the average k=1.4 times more than the total volume of removal because of additional transfers.2.1. Removal intensityIt is known that the removal intensity for one year is irregular and cannot be considered as a stationary process. The study of the character of non-stationary flow of road trains at 23 enterprises Sverdlesprom for five years has shown that the monthly removal intensity even for one enterprise essentially varies from year to year. This is explained by the complex of various systematic and random effects which exert an influence on removal: weather conditions, conditions of roads and lorry fleet, etc. All wood brought to the log store should, however, be processed within one year.Therefore, the less possibility of removing wood in the season between spring and autumn, the more intensively the wood removal should be performed in winter. While in winter the removal intensity exceeds the processing considerably, in summer, in most cases, the more full-length logs are processedthan are taken out.From the analysis of 118 realizations of removal values observed for one year, it is possible to evaluate the relative removal intensity g(t) as percentages of the annual load turnover. The removal data fisted in Table 1 is considered as expected values for any crane, which can be applied to the estimation of fatigue life, and, particularly, for an inspected crane with which strain measurement was carried out (see later). It would be possible for each crane to take advantage of its load turnover per one month, but to establish these data without special statistical investigation is difficult. Besides, to solve the problem of life prediction a knowledge of future loads is required, which we take as expected values on cranes with similar operation conditions.The distribution of removal value Q(t) per month performed by the relative intensity q(t) is written aswhere Q is the annual load turnover of a log store, A is the maximal designed store of logs in percent of Q. Substituting the value Q, which for the inspected crane equals 400,000 m3 per year, and A=10%, the volumes of loads transferred by the crane are obtained, which are listed in Table 2, with the total volume being 560,000 m3 for one year using K,.2.2. Number of loading blocksThe set of operations such as clamping, hoisting, transferring, lowering, and getting rid of a load can be considered as one operation cycle (loading block) of the crane. As a result to investigations, the operation time of a cycle can be modeled by the normal variable with mean equal to 11.5 min and standard deviation to 1.5 min. unfortunately, this characteristic cannot be simply used for the definition of the number of operation cycles for any work period as the local processing is extremely irregular. Using a total operationtime of the crane and evaluations of cycle durations, it is easy to make large errors and increase the number of cycles compared with the real one. Therefore, it is preferred to act as follows.The volume of a unit load can be modeled by a random variable with a distribution function(t) having mean22 m3 and standard deviation 6;一3 m3, with the nominal volume of one pack being 25 m3. Then, knowing the total volume of a processed load for a month or year, it is possible to determine distribution parameters of the number of operation cycles for these periods to take advantage of the methods of renewal theory [1].According to these methods, a random renewal process as shown in Fig. 2 is considered, where the random volume of loads forms a flow of renewals:In renewal theory, realizations of random:，，，having a distribution function F-(t), are understoodas moments of recovery of failed units or request receipts. The value of a processed load:，，after}th operation is adopted here as the renewal moment.＜t﹜. The function F-(t) is defined recurrently,Let F(t)=P﹛nLet v(t) be the number of operation cycles for a transferred volume t. In practice, the total volume of a transferred load is essentially greater than a unit load, and it is useful therefore totake advantage of asymptotic properties of the renewal process. As follows from an appropriatelimit renewal theorem, the random number of cycles v required to transfer the large volume t hasthe normal distribution asymptotically with mean and variance.without dependence on the form of the distribution function月t) of a unit load (the restriction is imposed only on nonlattice of the distribution).Equation (4) using Table 2 for each averaged operation month,function of number of load cycles with parameters m,. and 6,., which normal distribution in Table 3. Figure 3 shows the average numbers of cycles with 95 % confidence intervals. The values of these parametersfor a year are accordingly 12,719 and 420 cycles.3. Strain measurementsIn order to reveal the most loaded elements of the metalwork and to determine a range of stresses, static strain measurements were carried out beforehand. Vertical loading was applied by hoisting measured loads, and skew loading was formed with a tractor winch equipped with a dynamometer. The allocation schemes of the bonded strain gauges are shown in Figs 4 and 5. As was expected, the largest tension stresses in the bridge take place in the bottom chord of the truss (gauge 11-45 MPa). The top chord of the truss is subjected to the largest compression stresses.The local bending stresses caused by the pressure of wheels of the crane trolleys are added to the stresses of the bridge and the load weights. These stresses result in the bottom chord of the I一beambeing less compressed than the top one (gauge 17-75 and 10-20 MPa). The other elements of the bridge are less loaded with stresses not exceeding the absolute value 45 MPa. The elements connecting the support with the bridge of the crane are loaded also irregularly. The largest compression stresses take place in the carrying angles of the interior panel; the maximum stresses reach h0 MPa (gauges 8 and 9). The largest tension stresses in the diaphragms and angles of the exterior panel reach 45 MPa (causes 1 and hl.The elements of the crane bridge are subjected, in genera maximum stresses and respond weakly to skew loads. The suhand, are subjected mainly to skew loads.1, to vertical loads pports of the crane gmmg rise to on the otherThe loading of the metalwork of such a crane, transferring full-length logs, differs from that of a crane used for general purposes. At first, it involves the load compliance of log packs because of progressive detachment from the base. Therefore, the loading increases rather slowly and smoothly.The second characteristic property is the low probability of hoisting with picking up. This is conditioned by the presence of the grab, which means that the fall of the rope from the spreader block is not permitted; the load should always be balanced. The possibility of slack being sufficient to accelerate an electric drive to nominal revolutions is therefore minimal. Thus, the forest traveling gantry cranes are subjected to smaller dynamic stresses than in analogous cranes for general purposes with the same hoisting speed. Usually, when acceleration is smooth, the detachment of a load from the base occurs in 3.5-4.5 s after switching on an electric drive. Significant oscillations of the metalwork are not observed in this case, and stresses smoothly reach maximum values.When a high acceleration with the greatest possible clearance in the joint between spreader andgrab takes place, the tension of the ropes happens 1 s after switching the electric drive on, the clearance in the joint taking up. The revolutions of the electric motors reach the nominal value in O.}r0.7 s. The detachment of a load from the base, from the moment of switching electric motors on to the moment of full pull in the ropes takes 3-3.5 s, the tensions in ropes increasing smoothly to maximum. The stresses inthe metalwork of the bridge and supports grow up to maximum values in 1-2 s and oscillate about an average within 3.5%.When a rigid load is lifted, the accelerated velocity of loading in the rope hanger and metalwork is practically the same as in case of fast hoisting of a log pack. The metalwork oscillations are characterized by two harmonic processes with periods 0.6 and 2 s, which have been obtained from spectral analysis. The worst case of loading ensues from summation of loading amplitudes so that the maximum excess of dynamic loading above static can be 13-14%.Braking a load, when it is lowered, induces significant oscillation of stress in the metalwork, which can be }r7% of static loading. Moving over rail joints of 3} mm height misalignment induces only insignificant stresses. In operation, there are possible cases when loads originating from various types of loading combine. The greatest load is the case when the maximum loads from braking of a load when lowering coincide with braking of the trolley with poorly adjusted brakes.4. Fatigue loading analysisStrain measurement at test points, disposed as shown in Figs 4 and 5, was carried out during the work of the crane and a representative number of stress oscillograms was obtained. Since a common operation cycle duration of the crane has a sufficient scatter with average value } 11.5min, to reduce these oscillograms uniformly a filtration was implemented to these signals, and all repeated values, i.e. while the construction was not subjected to dynamic loading and only static loading occurred, were rejected. Three characteristic stress oscillograms (gauge 11) are shown inFig. 6 where the interior sequence of loading for an operation cycle is visible. At first, stressesincrease to maximum values when a load is hoisted. After that a load is transferred to the necessary location and stresses oscillate due to the irregular crane movement on rails and over rail joints resulting mostly in skew loads. The lowering of the load causes the decrease of loading and forms half of a basic loading cycle.4.1. Analysis of loading process amplitudesTwo terms now should be separated: loading cycle and loading block. The first denotes one distinct oscillation of stresses (closed loop), and the second is for the set of loading cycles during an operation cycle. The rain flow cycle counting method given in Ref. [2] was taken advantage of to carry out the fatigue hysteretic loop analysis for the three weakest elements: (1) angle of the bottom chord(gauge 11), (2) I-beam of the top chord (gauge 17), (3) angle of the support (gauge 8). Statistical evaluation of sample cycle amplitudes by means of the Waybill distribution for these elements has given estimated parameters fisted in Table 4. It should be noted that the histograms of cycle amplitude with nonzero averages were reduced afterwards to equivalent histograms with zero averages.4.2. Numbers of loading cyclesDuring the rain flow cycle counting procedure, the calculation of number of loading cycles for the loading block was also carried out. While processing the oscillograms of one type, a sample number of loading cycles for one block is obtained consisting of integers with minimum and maximum observed values: 24 and 46. The random number of loading cycles vibe can be describedby the Poisson distribution with parameter =34.Average numbers of loading blocks via months were obtained earlier, so it is possible to find the appropriate characteristics not only for loading blocks per month, but also for the total number of loading cycles per month or year if the central limit theorem is taken advantage of. Firstly, it is known from probability theory that the addition of k independent Poisson variables gives also a random variable with the Poisson distribution with parameter k},. On the other hand, the Poisson distribution can be well approximated by the normal distribution with average}, and variation },. Secondly, the central limit theorem, roughly speaking, states that the distribution of a large number of terms, independent of the initial distribution asymptotically tends to normal. If the initial distribution of each independent term has a normal distribution, then the average and standard deviation of the total number of loading cycles for one year are equal to 423,096 and 650 accordingly. The values of k are taken as constant averages from Table 3.5. Stress concentration factors and element enduranceThe elements of the crane are jointed by semi-automatic gas welding without preliminary edge preparation and consequent machining. For the inspected elements 1 and 3 having circumferential and edge welds of angles with gusset plates, the effective stress concentration factor for fatigue is given by calculation methods [3], kf=2.}r2.9, coinciding with estimates given in the current Russian norm for fatigue of welded elements [4], kf=2.9.The elements of the crane metalwork are made of alloyed steel 09G2S having an endurance limit of 120 MPa and a yield strength of 350 MPa. Then the average values of the endurance limits of the inspected elements 1 and 3 are ES一l=41 MPa. The variation coefficient is taken as 0.1, and the corresponding standard deviation is 6S-、一4.1 MPa.The inspected element 2 is an I-beam pierced by holes for attaching rails to the top flange. The rather large local stresses caused by local bending also promote fatigue damage accumulation. According to tablesfrom [4], the effective stress concentration factor is accepted as kf=1.8, which gives an average value of the endurance limit as ES 一l=h7 Map. Using the same variation coiffing dent th e stand arid d emit ion is 1s σ-=6.7 MPa.An average S-N curve, recommended in [4], has the form:with the inflexion point No=5·106 and the slope m=4.5 for elements 1 and 3 and m=5.5 for element 2.The possible values of the element endurance limits presented above overlap the ranges of load amplitude with nonzero probability, which means that these elements are subjected to fatigue damage accumulation. Then it is possible to conclude that fatigue calculations for the elements are necessary as well as fatigue fife prediction.6. Life predictionThe study has that some elements of the metalwork are subject to fatigue damage accumulation.To predict fives we shall take advantage of intrinsic fatigue curves, which are detailed in [5]and [6].Following the theory of intrinsic fatigue curves, we get lognormal life distribution densities for the inspected elements. The fife averages and standard deviations are fisted in Table 5. The lognormal fife distribution densities are shown in Fig. 7. It is seen from this table that the least fife is for element 3. Recollecting that an average number of load blocks for a year is equal to 12,719, it is clear that the average service fife of the crane before fatigue cracks appear in the welded elements is sufficient: the fife is 8.5 years for element 1, 11.5 years for element 2, and h years for element 3. However, the probability of failure of these elements within three-four years is not small and is in the range 0.09-0.22. These probabilities cannot be neglected, and services of design and maintenance should make efforts to extend the fife of the metalwork without permitting crack initiation and propagation.7. ConclusionsThe analysis of the crane loading has shown that some elements of the metalwork are subjectedto large dynamic loads, which causes fatigue damage accumulation followed by fatigue failures.The procedure of fatigue hfe prediction proposed in this paper involves tour parts:(1) Analysis of the operation in practice and determination of the loading blocks for some period.(2) Rainflow cycle counting techniques for the calculation of loading cycles for a period of standard operation.(3) Selection of appropriate fatigue data for material.(4) Fatigue fife calculations using the intrinsic fatigue curves approach.The results of this investigation have been confirmed by the cases observed in practice, and the manufacturers have taken a decision about strengthening the fixed elements to extend their fatigue lives.中文翻译龙门式起重机金属材料的疲劳强度预测v.a.科普诺夫摘要内在的疲劳曲线应用到龙门式起重机金属材料的疲劳寿命预测问题。

机械工程毕业设计外文翻译

毕业设计论文外文资料原文及译文学院：机电工程学院专业：机械设计制造及其自动化班级：学号：姓名：Mechanical engineering1.The porfile of mechanical engineeringEngingeering is a branch of mechanical engineerig,it studies mechanical and power generation especially power and movement.2.The history of mechanical engineering18th century later periods,the steam engine invention has provided a main power fountainhead for the industrial revolution,enormously impelled each kind of mechznical biting.Thus,an important branch of a new Engineering – separated from the civil engineering tools and machines on the branch-developed together with Birmingham and the establishment of the Associantion of Mechanical Engineers in 1847 had been officially recognized.The mechanical engineering already mainly used in by trial and error method mechanic application technological development into professional engineer the scientific method of which in the research,the design and the realm of production used .From the most broad perspective,the demend continuously to enhance the efficiencey of mechanical engineers improve the quality ofwork,and asked him to accept the history of the high degree of education and training.Machine operation to stress not only economic but also infrastructure costs to an absolute minimun.3.The field of mechanical engineeringThe commodity machinery development in the develop country,in the high level material life very great degree is decided each kind of which can realize in the mechanical engineering.Mechanical engineers unceasingly will invent the machine next life to produce the commodity,unceasingly will develop the accuracy and the complexity more and more high machine tools produces the machine.The main clues of the mechanical development is:In order to enhance the excellent in quality and reasonable in price produce to increase the precision as well as to reduce the production cost.This three requirements promoted the complex control system development.The most successful machine manufacture is its machine and the control system close fusion,whether such control system is essentially mechanical or electronic.The modernized car engin production transmission line(conveyer belt)is a series of complex productions craft mechanizationvery good example.The people are in the process of development in order to enable further automation of the production machinery ,the use of a computer to store and handle large volumes of data,the data is a multifunctional machine tools necessary for the production of spare parts.One of the objectives is to fully automated production workshop,three rotation,but only one officer per day to operate.The development of production for mechanical machinery must have adequate power supply.Steam engine first provided the heat to generate power using practical methods in the old human,wind and hydropower,an increase of engin .New mechanical engineering industry is one of the challenges faced by the initial increase thermal effciency and power,which is as big steam turbine and the development of joint steam boilers basically achieved.20th century,turbine generators to provide impetus has been sustained and rapid growth,while thermal efficiency is steady growth,and large power plants per kW capital consumption is also declining.Finally,mechanical engineers have nuclear energy.This requires the application of nuclear energy particularly high reliability and security,which requires solving many new rge power plants and the nuclear power plant control systems have become highly complex electroonics,fluid,electricity,water and mechanical parts networks All in all areas related to the mechanical engineers.Small internal combustion engine,both to the type (petrol and diesel machines)or rotary-type(gas turbines and Mong Kerr machine),as well as their broad application in the field of transport should also due to mechanical enginerrs.Throughout the transport,both in the air and space,or in the terrestrial and marine,mechanial engineers created a variety of equipment and power devices to their increasing cooperation with electrical engineers,especially in the development of appropration control systems.Mechanical engineers in the development of military weapons technology and civil war ,needs a similar,though its purpose is to enhance rather than destroy their productivity.However.War needs a lot of resources to make the area of techonlogy,many have a far-reaching development in peacetime efficiency.Jet aircraft and nuclear reactors are well known examples.The Biological engineering,mechanical engineering biotechnology is a relatively new and different areas,it provides for the replacement of the machine or increase thebody functions as well as for medical equipment.Artficial limbs have been developed and have such a strong movement and touch response function of the human body.In the development of artificial organ transplant is rapid,complex cardiac machines and similar equipment to enable increasingly complex surgery,and injuries and ill patients life functions can be sustained.Some enviromental control mechanical engineers through the initial efforts to drainage or irrigation pumping to the land and to mine and ventilation to control the human environment.Modern refrigeration and air-conditioning plant commonaly used reverse heat engine,where the heat from the engine from cold places to more external heat.Many mechanical engineering products,as well as other leading technology development city have side effects on the environment,producing noise,water and air pollution caused,destroyed land and landscape.Improve productivity and diver too fast in the commodity,that the renewable naturalforces keep pace.For mechanical engineers and others,environmental control is rapidly developing area,which includes a possible development and production of small quantities of pollutants machine sequnce,and the development of new equipment and teachnology has been to reduce and eliminate pollution.4.The role of mechanical engineeringThere are four generic mechanical engineers in common to the above all domains function.The 1st function is the understanding and the research mechanical science foundation.It includes the power and movement of the relationship dynamics For example,in the vibration and movement of the relationship;Automatic control;Study of the various forms of heart,energy,power relations between the thermodynamic;Fluidflows; Heat transfer; Lubricant;And material properties.The 2nd function will be conducts the research,the desing and the development,this function in turn attempts to carry on the essential change to satisfy current and the future needs.This not only calls for a clear understanding of mechanical science,and have to breakdown into basic elements of a complex system capacity.But also the need for synthetic and innovative inventions.The 3rd function is produces the product and the power,include plan,operation and maintenance.Its goal lies in the maintenance eitherenhances the enterprise or the organization longer-tern and survivabilaty prestige at the same time,produces the greatest value by the least investments and the consumption.The 4th function is mechanical engineer’s coordinated function,including the management,the consultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use the science for a long time the method,but is not traditional or the intuition method tendency,this is a mechanical engineering skill aspect which unceasingly grows.These new rationalization means typical names include:The operations research,the engineering economics,the logical law problem analysis(is called PABLA) However,creativity is not rationalization.As in other areas,in mechanical engineering,to take unexpected and important way to bring about a new capacity,still has a personal,marked characteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,such as:the instrument and the measuring appliance in very many situations,the machine design must use the knowledge of discipline the and so on mathematics,materials science and mechanics.Mechanical engineering desgin includeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnical engineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Design stages.The entire desgin process from start to finish,in the process,a demand that is designed for it and decided to do the start.After a lot of repetition,the final meet this demand by the end of the design procees and the plan.Design considerations.Sometimes in a system is to decide which parts needs intensity parts of geometric shapesand size an important factor in this context that we must consider that the intensity is an important factor in the design.When we use expression design considerations,we design parts that may affect the entire system design features.In the circumstances specified in the design,usually for a series of such functions must be taken into account.Howeever,to correct purposes,we should recognize that,in many cases thedesign of important design considerations are not calculated or test can determine the components or systems.Especially students,wheen in need to make important decisions in the design and conduct of any operation that can not be the case,they are often confused.These are not special,they occur every day,imagine,for example,a medical laboratory in the mechanical design,from marketing perspective,people have high expectations from the strength and relevance of impression.Thick,and heavy parts installed together:to produce a solid impression machines.And sometimes machinery and spare parts from the design style is the point and not the other point of view.Our purpose is to make those you do not be misled to believe that every design decision will needreasonable mathematical methods.Manufacturing refers to the raw meterials into finished products in the enterprise.Create three distinct phases.They are:input,processing exprot.The first phase includes the production of all products in line with market needs essential.First there must be the demand for the product,the necessary materials,while also needs such as energy,time,human knowledge and technology resourcess .Finall,the need for funds to obtain all the other resources. Lose one stage after the second phase of the resources of the processes to be distributed.Processing of raw materials into finished products of these processes.To complete the design,based on the design,and then develop plans.Plan implemented through various production processes.Management of resources and processes to ensure efficiency and productivity.For example,we must carefully manage resources to ensure proper use of funds.Finally,people are talking about the product market was cast.Stage is the final stage of exporting finished or stage.Once finished just purchased,it must be delivered to the users.According to product performance,installation and may have to conduct further debugging in addition,some products,especially those very complex products User training is necessary.6.The processes of materials and maunfacturingHere said engineering materials into two main categories:metals and non-ferrous,high-performance alloys and power metals.Non-metallic futher divided into plastice,synthetic rubber,composite materials and ceramics.It said the productionproccess is divided into several major process,includingshape,forging,casting/ founding,heat treatment,fixed/connections ,measurement/ quality control and materal cutting.These processes can be further divide into each other’s craft.Various stages of the development of the manufacturing industry Over the years,the manufacturing process has four distinct stages of development, despite the overlap.These stages are:The first phase is artisanal,the second Phase is mechanization.The third phase is automation the forth Phase is integrated.When mankind initial processing of raw materials into finished products will be,they use manual processes.Each with their hands and what are the tools manuslly produced.This is totally integrated production take shape.A person needs indentification,collection materials,the design of a product to meet that demand,the production of such products and use it.From beginning to end,everything is focused on doing the work of the human ter in the industrial revolution introduced mechanized production process,people began to use machines to complete the work accomplished previously manual. This led to the specialization.Specialization in turn reduce the manufacture of integrated factors.In this stage of development,manufacturing workers can see their production as a whole represent a specific piece of the part of the production process.One can not say that their work is how to cope with the entire production process,or how they were loaded onto a production of parts finished.Development of manufacting processes is the next phase of the selection process automation.This is a computer-controlled machinery and processes.At this stage,automation island began to emerge in the workshop lane.Each island represents a clear production process or a group of processes.Although these automated isolated island within the island did raise the productivity of indivdual processes,but the overall productivity are often not change.This is because the island is not caught in other automated production process middle,but not synchronous with them .The ultimate result is the efficient working fast parked through automated processes,but is part of the stagnation in wages down,causing bottlenecks.To better understand this problem,you can imagine the traffic in the peak driving a red light from the red Service Department to the next scene. Occasionally you will find a lot less cars,more than being slow-moving vehicles,but the results can be found by thenext red light Brance.In short you real effect was to accelerate the speed of a red Department obstruction offset.If you and other drivers can change your speed and red light simultaneously.Will advance faster.Then,all cars will be consistent,sommth operation,the final everyone forward faster.In the workshop where the demand for stable synchronization of streamlined production,and promoted integration of manufacturing development.This is a still evolving technology.Fully integrated in the circumstances,is a computer-controllrd machinery and processing.integrated is completed through computer.For example in the preceding paragraph simulation problems,the computer will allow all road vehicles compatible with the change in red.So that everyone can steady traffic.Scientific analysis of movement,timing and mechanics of the disciplines is that it is composed of two pater:statics and dynamics.Statics analyzed static system that is in the system,the time is not taken into account,research and analysis over time and dynamics of the system change.Dynameics from the two componets.Euler in 1775 will be the first time two different branches: Rigid body movement studies can conveniently divided into two parts:geometric and mechanics.The first part is without taking into account the reasons for the downward movement study rigid body from a designated location to another point of the movement,and must use the formula to reflect the actual,the formula would determine the rigid body every point position. Therefore,this study only on the geometry and,more specifically,on the entities from excision.Obviously,the first part of the school and was part of a mechanical separation from the principles of dynamics to study movement,which is more than the two parts together into a lot easier.Dynamics of the two parts are subsequently divided into two separate disciplines,kinematic and dynamics,a study of movement and the movement strength.Therefore,the primary issue is the design of mechanical systems understand its kinematic.Kinematic studies movement,rather than a study of its impact.In a more precise kinematic studies position,displacement,rotation, speed,velocity and acceleration of disciplines,for esample,or planets orbiting research campaing is a paradigm.In the above quotation content should be pay attention that the content of the Euler dynamics into kinematic and rigid body dynamics is based on the assumptionthat they are based on research.In this very important basis to allow for the treatment of two separate disciplines.For soft body,soft body shape and even their own soft objects in the campaign depends on the role of power in their possession.In such cases,should also study the power and movement,and therefore to a large extent the analysis of the increased complexity.Fortunately, despite the real machine parts may be involved are more or less the design of machines,usually with heavy material designed to bend down to the lowest parts.Therefore,when the kinematic analysis of the performance of machines,it is often assumed that bend is negligible,spare parts are hard,but when the load is known,in the end analysis engine,re-engineering parts to confirm this assnmption.机械工程1.机械工程简介机械工程是工程学的一个分支，它研究机械和动力的产，尤其是力和动力。

机械制造专业毕业设计外文翻译--制造分析

MANUFACTURING ANALYSIS:HOW MUCH FLEXIBILITY?In addition to production systems that fabricate very high quality products,at low cost,and with ultrarapid delivery,many strategic planners and economists point to the need for flexibility.Publications from Japan(Yoshio,1994;Ohsono,1995)express a similar view,and the more recent J.D.Powers comparative surveys on automobiles indicate that"now that others are closing the quality gap,the Japanese have to compete in other areas"(see Rechtin,1994;and the annual J.D.Powers report series).Emphasis is thus place on these combined factors of quality,cost,delivery,and flexibility(QCDF).The ability to react to smaller lot sizes and the quest for ultrarapid delivery are major conconcerns,culminating in the possbility of a three-day car(Iwata et al.,1990_.In an ideal situation,once the various market sectors have been established,production will settle into a groove and be constantly refined and improved but with no major upheavals.Unfortunately,in recent years,manufacturers have not been able to rely on long periods of uninterrupted production because events in the world economy have forced rapid changes in consumer demand and the range of consumer preferences.Henry Ford"s favorite aphorism-that his cutomers could have any color of car they wanted as long as it was black-is in sharp contrast to today's range of consumer preferences.This has led to the proposal by some academics that manufactering can be built for "customized mass production."This sounds nice on first hearing.Howerver,for products like automobiles,the degree of customization can go only so far for a given batch size and price point.Only hyperwealthy CEOs and movie stars can get precise customization in products like automobiles.Nevertheless,an ability to be prepared for any sudden market shifts is becoming more of an issue.As new equipment is purchased,manufacturing companies must decide between harware that isdedicate to only a few tasks and is thus relatively inexpensive,and more costly but more versatile equipment that might perform unforeseen tasks in the future.The methodologies for analyzing capital expenditures,returns=on-investment(ROI),and depreciations are given in many texts (see Parkin,1992).these can be used to analyze the ROI for new machinery that has been identified as useful and is therefore about to be purchased.However,since today's market trends are so uncertain,such analyses do not help to predict the specific systems to install in the firt place.The hope is that some of the engineering solutions will provide much more flexible machinery for only a modest increase in cost(Greeenfeld et al.,1989).In this way,the investment dilemna might be less critical.The preceding discussions emphasize that flexibility is a main challenge for the continued growth of a mew company.The main question is:Can a design and fabrication system that is first set up to respond to one market sector be quickly reconfiqured to respond to the needs of another market sector,or even another product,and be just as efficient?Today,the answer to this question is"probably not."For example,if a machine shop is well equipped with lathes but has no vertical boring machines,there will be a natural limit on achievable tolerances.It is unlikely that it will be able to suddenly jump from truck transmissions to helicopter teansmissions.And even in the reverse scenario,if a shop has dedicated itself to precision boring.it is unlikely that the equipment and the craftspeople will be able to br quickly redeployed in a cost-effective manner to routine production procedures and less demanding tolerances;their competitive advantage would be lost.These same comparisons can be made for semiconductor manufacturing.Manufacturers who are currently focusing on the high-volume production of memory chips will not readily switch to application-specific devices or vece versa.The general conclusion may be drawn that today's manufacturingtools-specifically manufacturing systems-are still too dedicated to specific machine tools, robots,and manuvacturing systems-are still too dedicated yo specific market sectors and are not flexible enough.This general need for flexibl,reconfigurable manufacturing systems was of course a key aspect of CIMi its original xonception.Merchant(1980)led a number of industy forecasts between 1969and 1971 that refined the details and needs of the CIM philosophy.However,theseforecasts overestimated the rate at which flexible manufacturing systems ang related technology would be asorbed into factories.During the 1970s and 1980s,machines exchanged”handshakes”when tasks were completed.If these tasks were completes properly and on tim,then a flexible manufacturing system(FMS)continued to operate satisfactorily.However,if the machines went seriously out of bounds,then the communicaations broke down and too frequent human intervention wasneeded to make the FMS efficient.Duringthis era,the experiences of several research and development groups showed that the inadequacy of cell communication software was probably the key impediment to the industrial acceptance of CIM(Harrington,1973;Merchant,1980;Bjorke,1979).Of interest was that by the late 1980s.the review articles on CIMwere advocating much smaller FMSs of only three or four maxhines as the most efficient way of utilizing the cell concept.Allthese trens suggestes more sophisticated computer-and sensorbased techniques at the factory floor.as described later.2.6.1Design for Flexibility(Reuse)Design for flexibility in the automobile industry can pay off in a bigway if there is some reusability of fixture families.The automated assembly lines where the frames, doors, and chassis are asembled with robots and welded together are obviously intensely expensive.These are suall two_story-high lines as big as many football fields whererobots,fixtures,and alignment cradles bring the body components together for welding and assemblu.The intense cost of these lines is hard to picture without a visit to a standard automobile plant.The key issue is to maximize the use and reuse of these fixuring lines.If desigers were allowed total freedom, each vehicle in the familu might require special tooling,This would not allow cost-effective manufacturing.As mintioned earlier.this factor places an important responsibility on the designer.In an ideal situation the newly designed component will be made on exisig factory-floor machinery,readily leading to an “off_the-shelf”automation solution,In the best case,existing fixtures and even some parts of existing dies will also reused.Some companies,those with smaller batch sizes,might use a mixed production line.As one views such a line, several body styles go by:perhaps the mix is as simple as regular sedans and station wagons.but the mix can often be stretched beyond this to dufferent cars of more or less the same size.With good design for multiple usability,many of the hard fixtures and robots cah be used gor all the differing vehicles in the family.Also,with good cooperation between manufacturing and design,the existing robots and fixtures might even be able to “upwardly constrain the vehicle design space”foor future vehickes.Therefore,viewed across several years and more than one family of vehickes,automation costs are relatively lower per indevidual vehicle2.62 Concluding Remarks:design Aesthetics versus ManufacturingJust to keep a proper perspective at the close ofthis subsection,it must ve emphasized that design for manufacturability(or flxibility)has to be prudently app;ied with the perceived end user constantly i n mind ,The Japanese articles concerned with TQM(Yoshio,1994;Iwata et al.,1990;see Haiser and Clausing,1988)increasingly emphasize the more qualitative aspectsof aesthetics as one of their next thrusts, even though this is muchmore defficult to measure as a design objective.At one extreme,a component that is destined to be buries deep in a car,a washing machine,or a furnace does not need to look good.DFM and DFA methods can be applied at very step in Figure2.1.At one extreme,there will always be a market for high-quality expensive products such as the $300 polo shirt disscussed in Section 2.4.10,a new Jaguar,or an expensive Bang and Olfson music system.In these cases the buyer is actively seeking style and luxury.Therefore,the design-for-manufacturability engineers cannot have it all their own way, or a car might end up ;ooking lke a rectangular box on fourwheels:cheap,it is true,but hard to sell.To conclude with personal observations, it is ckear from visits to Tokyo and Kyoto that wealthy Japanese people prefer a Mercdes Benz,.a BM,a Jaguar, or the large Tootas and Accuras.Not many American cars are seen on the streets,even in the financial districts and embassy areas of Yokyo.One does see the occasional Cadillac,some fully loaded Jeeps, and some of the newer Ford Mustangs,but not many.The”Big Three”panies complain that the reason for this is that Japanimposes trade barriers on U.S.vehicles.However,perhaps the real reason is that a wealthy Japanese businessman wants a car with brando.This us a Japanese phrase meaning “brand appeal.”So,perhaps U.S.cars in Japan just do not have enough brando at the present time.After all, Japan is swamped wuth ither U.S.products that do have brando:Lecu’s 501,McDonald’sHollywood action movies,and CDs by American musicians.And,inevitably,the Starbuck’sCoffee shops in Tokyo are swamped.The moral of the story is that product design and product manufacturing have art and irrational emotions lurking in their corners that design and manufacturing engineers should not ignore.2.7 MANAGEMENT OF TECHNOLOGYChapter 1 reviewed the art,technology,science,and business of manufacturing,.During the last 100 years design and manufacturing have clearly moved from an art/technology endeavor to a business/science endeavor.Empatically,in this new business/science envronment,being gift in just the science and technology is not enough to win the day.Specifically,U.S.manufacturing in the late 1980s was clearly in a panic.Basicindustries such as semiconductors,automobiles,consumer electronics,and machine tools were all losing out to international competitor.Today,things do seem a lot better on all fronts.In'How the Words Sees Us"the New YorkTimes boldly stated:"Our technology-computerized weapon systems,medical scanners, the Internet-sets the standard to which developing countries aspire."No single miracle has happened,but steady progress has occurred in:●Creativity in design and manufacturing●Quality assurance and control of bbasic manufacturing methods●Downsizing companies to be more efficient●Global commerce●Internet commerce●The fact that some of our international competitors did not fare too well and struggled with unfavorable ccurrency exchange rates in the late-1990s also made it easier for panies to compete.At the time of this writing,the challenge for the future is to kkeep this real growth going .Fpr a few uears. U.S.,manufacturers were chasing their Psvigiv Rim and European competitors and even enjoying the athketic-event psychology of"coming from behind."Staying up with the front-runners or,better still,being ahead requires an extra degree ofcrestivity and commitment.Similar to the above list,perhps some specific areas for continued creativity include:●Further exploiting global markets through Internet commerce.●Focusing on cmplex systems,specifically developing CAD/CAM techniques for the electro/mechanical/biological products that are on the horizon.●Continuing with the time-ti-market awareness,balanced by aesthetic creativity.●Continually striving for the 6-sigma quality goal.●Creating an organization that can cope and even thrive on change.For example,all industries-from semiconductors,to machine shops, to steel mills-are being told to bemore environmentally conscious.Being so,and yet still being competitive with other countries that might care much less about issues such as pollution or industrial safety,challaenges manufacturers to be especially creative and efficient..Responding proactively to government funding opportunities,public policy,and federal regulationd that impact all industries at some level. For example,a project such as the original Internet was launched more than 25years ago by the Defense Advanced Research Project Agecy(DARPA),and it has continued to be nurtured by the National Seience Foundation(NSF).The MOSIS(2000)story is similar.It can thus be reasonably argued that much of the wealth of Silicon Valley in nouthern California and Route 128 near Boston had its birthplace in projects such as these .Companies that are willing to understand the constraints.and then cosponsor this type of federally funded research can benefit greatly.However, freaching consensus can often be frustrating and time-consuming,as seen recently in the regulations surrounding the tekecommunications industey.(On another constraining note in biotechnology,the FDA-supervised drug trials do impose a long period oftime between initial reserch and development (R&D)investments and the marketplace.Perhaps for this reason,many small biotechnology start-ups are bought out by the deep-pocket pharmaceutical companies.). The initial time-to-market of a new product and the ongoing delivery time of an established product are ongoing themes of this book.The integration issues that will be discussed around design,planing,and fabrication are obvious areas to focus on technically.In particular,new hardware and doftware environments allow the connections between design,planning,and fabrication to be simplified. Particular benefits include the reduction of the time taken to obtain the first prototype of a designed object,whether it is a chip or a computer casing.New techniques and standards for distributed software systems also provide a more information-rich dialogue between the design function and the manufacturing function.The ability to rapidly obtain an initial prototype allows designers to assess the aesthetic aspects of a design. It also allows a preliminary analysis of how a single object in a subassembly will interact with mating componets,and finally allows some preliminary decisions to be made on the future manufacturing methods for the componnt.The bene fits of obtaining an initial physical prototype are seen to embrace both the component itself and the way in which the component will be produced.The ability to evaluate both the probuct and the process by which it will be made is an essential concept in concurrent or simultaneous engineering.Although there will be many new trends and unexpected disturbances, one basic business goal will remain constant:the winners will be those who desogn,plan and manufacture a high-quality product at the right price and get it to market first.To address this need,Chapter 2 has considered some general principles of manufacturing analysis in the context of four parameters;quality,cost,delivery,and flexibility(QCDF).Generic approaches for quality assurance methods were also reviewed. The chapteralso discussed some guiding subprinciples for process selection in mechanical manufacturing.制造分析灵活性程度制造系统除了有生产产品的高质量,低成本,超快的流通速度外,许多学者和经济学家指出了灵活性的需要.美国和欧州的文章特别谈到柔性制造系统的需要,这些揉性制造系统涉及在生产流程的各个环节提高其灵活性和流动性.通过一个固件或在几个固件中整合组成产品的零部件,以及软件和信息流系统的整合.日本出版的文章表达了相似的观点,最近,杰.帝力量对汽车的比较性调查表明:既然他们追求质量,那日本就因该在别的领域和他们竞争,分析强调在质量,价格,流动,灵活性这些综合性要素.在理想的情形中,各种市场一旦建立,生产就会马上上轨,并无波动地进行调整和改进.不幸的是,在最近几年,生产已经不可能长时期无间断进行,因为再经济领域的事情已经使消费者的需求和选择范围快速变化.亨利.福德的格言:他的客户可以拥有他们想要的任何颜色的汽车,只要是黑色.是和现在消费者选择范围多样的强烈对比.这导致了一些学者建议制造业可以建立在大批量定单式生产基础上.这最初听起来不错.但是,象汽车这样的产品,客户的需求满足度只能是在给定的批料尺寸和价格基点上.只有总裁和电影明星才能在汽车这样的产品上随便选择.然而,市场波动的适应能力正越来越被重视.对于购购买的机器,制造公司应该权衡利弊,是选择那些功能比较少,但价格相对较低的,还是选择价格贵,功能多,能执行未来没预测的任务的.对资金消耗,投资回报,价格下跌的分析在很多事例中都有体现.这些可以用来分析那些被认为有用并因此即将购买的新机器的投资回报.然而,因为今天的市场动向是那么不确定,这样的分析不能帮助预测首要的具体系统.希望其它的工程问题的解决方法可以提供更多的柔性制造,价格上相应少许提高,这样投资困境就不会那么严重.前面的论述强调灵活性对新公司的持续性发展是一个主要的挑战.主要问题是,一个主要建立在对市场灵活反应的基础上的设计与制造系统能否迅速对另外一个市场甚至另外一个产品作出快速有效的调整.今天,这个问题的答案是:可能还不能.例如,一个用车床很好地装配了的车间,没有垂直镗钻床.要达到所要求的公差,就有天然的不便.它不象有可能由汽车传输突然跳到直升飞机传输那样,即使在相反的境况下,车间装配了镗床,设备和操作人员也不可能很快地在有资金下重新配置,去改变生产工序和减少需求公差,他们的竞争优势就会丧失.这种同样的比较也可以在半导体制造上作出.现时正密切关注大容量芯片的制造商不会马上去办理申请和配置机器.可以得出的大致结论是:今天的制造机器,包括具体的机床,工业机器人,和制造系统仍然与具体的销路密切相关,还不够灵活.灵活性的需求,重新配制制造系统也是计算机集程制造系统在它最初意义上的主要方面.商人在1969到1971作出的预测,提炼计算机集成制造系统科学的细节和需求.然而,这种预测过高估计了被制造厂运用的柔性制造系统和相关技术水平.在十九世纪七十年代和十九世纪八十年代,任务完成以后机器更新换代.假如任务正确准时完成,柔性制造系统继续满意地运作. 然而,如果机器跳动严重,联系中断,为了使系统有效进行,频繁的人为界入就变的需要.在这段时期,几个研究与发展组织经验表明联系软件细胞的不精确可能是计算机集成制在工业中运用的主要障碍.有意思的是,到了九十年代末,回顾计算机集成制造的文章比柔性制造系统少得多,只有三种或四种机器被认为有此种性能.所有这些趋势需求熟练的电脑技术和制造层面感应技术.2.6.1灵活性设计(再利用)在气车工业灵活性设计可以在一定程度上得到补偿,假如一些装置有再利用性.那些用工业机器人把门,框架,机架装配和焊接在一起的自动装配线明显昂贵.通常有像足球场大的装配线,在那里,工业机器人,固定装置,较正装置,把主要部件装配焊接在一起.没有亲自去标准自动工厂,你是无法知道其切确的耗资.主要的是尽可能地扩大这些生产线的利用和再利用价值.假如设计者给予完全的自由,加工组的所有装置都需要经过特别加工.将不允许价格昂贵的装置存在.就像前面提到的,这个因素在设计中有很大的依赖性.在理想的情形下,新的被设计部件是在现有的车间装置下,在脱离板的自动解决方法下设计而成的.理想的情形是现有的装置和一些无使用的装置可以被重新利用.一些小批量生产的公司,可能使用混合生产线.可能和一般的轿车和公车一样,简单.但在尺寸基本相同的不同轿车制造上,其更具灵活性.在优秀的多性能设计上,很多装置和自动机器人有多种使用性.当然,随着在设计与制造越来越多的合作,现有的机器有可能对未来装置变得更是一个制约.因此再过几年,随着更多加工中心的出现,其耗价有可能变得比单一装置更便宜.结论:设计美学与制造接下来为了作一个准确的预测,必须强调在消费者心里出存在的已经被运用的设计制造.日本的文章逐步强调产品的美学质量作为他们的下一个目标.虽然它很难作为一个具体的设计客体作衡量.极端情况,深藏在车里,洗衣机里,或炉里的零件就没有必要做得很好看.另外一种极端情况下,一些高质量高价格商品也有市场,比如三百美元的运动衫,一只美洲豹,昂贵的毒品.在这种情况下购买者寻找的是时髦与奢侈.因此,设计制造工程师不能按照他们自己的方式办,轿车就像在轮子上的矩型框,便宜,没错,但很难卖.通过个别的调查,得出结论,冲从东京到京都,富裕的日本人选择奔驰等.大街上美国轿车不是很多,即使在繁华街,和东京的使馆区.有时可以看到卡迪拉克,一些满载的吉普.和一些最新的马字达.但不是很多.美国三大公司抱怨说这是日本对美国商品制造关税壁垒.虽然,真正的原因是有钱的日本商人喜欢有品牌的商品,这在日本称做品牌效应,所以美国轿车现时在日本没有足够的品牌度.毕竟,日本市场被其他有品牌的美国商品占领. 如麦当劳,好来坞电影,美国音乐光盘.不可避免地,还有咖啡店.那文章的主旨在于设计与制造工程师不能忽视在设计与制造过程中的艺术和非理性的东西.2.7 技术管理过去一百年,设计与制造已经从纯技术领域的怒力向商品化方向努力转变.特别地,在这种商业化环境中,需要强调的是，再这种新的商业环境中要取得成功只靠科学技术是不行的，特别地，二十世纪八十年代末的美国制造业处于一种恐慌中基础工业如半导体，汽车，电子产品，机床都失去了国际竞争力。

机械类毕业设计外文翻译

本科毕业论文(设计)外文翻译学院：机电工程学院专业：机械工程及自动化姓名：高峰指导教师：李延胜2011年 05 月 10日教育部办公厅Failure Analysis，Dimensional Determination And Analysis，Applications Of Cams INTRODUCTIONIt is absolutely essential that a design engineer know how and why parts fail so that reliable machines that require minimum maintenance can be designed．Sometimes a failure can be serious，such as when a tire blows out on an automobile traveling at high speed．On the other hand，a failure may be no more than a nuisance．An example is the loosening of the radiator hose in an automobile cooling system．The consequence of this latter failure is usually the loss of some radiator coolant，a condition that is readily detected and corrected．The type of load a part absorbs is just as significant as the magnitude．Generally speaking，dynamic loads with direction reversals cause greater difficulty than static loads，and therefore，fatigue strength must be considered．Another concern is whether the material is ductile or brittle．For example，brittle materials are considered to be unacceptable where fatigue is involved．Many people mistakingly interpret the word failure to mean the actualbreakage of a part．However，a design engineer must consider a broader understanding of what appreciable deformation occurs．A ductile material，however will deform a large amount prior to rupture．Excessive deformation，without fracture，may cause a machine to fail because the deformed part interferes with a moving second part．Therefore，a part fails(even if it has not physically broken)whenever it no longer fulfills its required function．Sometimes failure may be due to abnormal friction or vibration between two mating parts．Failure also may be due to a phenomenon called creep，which is the plastic flow of a material under load at elevated temperatures．In addition，the actual shape of a part may be responsible for failure．For example，stress concentrations due to sudden changes in contour must be taken into account．Evaluation of stress considerations is especially important when there are dynamic loads with direction reversals and the material is not very ductile． In general，the design engineer must consider all possible modes of failure，which include the following．——Stress——Deformation——Wear——Corrosion——Vibration——Environmental damage——Loosening of fastening devicesThe part sizes and shapes selected also must take into account many dimensional factors that produce external load effects，such as geometric discontinuities，residual stresses due to forming of desired contours，and the application of interference fit joints．Cams are among the most versatile mechanisms available．A cam is a simple two-member device．The input member is the cam itself，while the output member is called the follower．Through the use of cams，a simple input motion can be modified into almost any conceivable output motion that is desired．Some of the common applications of cams are ——Camshaft and distributor shaft of automotive engine ——Production machine tools——Automatic record players——Printing machines——Automatic washing machines——Automatic dishwashersThe contour of high-speed cams (cam speed in excess of 1000 rpm) must be determined mathematically．However，the vast majority of cams operate at low speeds(less than 500 rpm) or medium-speed cams can be determined graphically using a large-scale layout．In general，the greater the cam speed and output load，the greater must be the precision with which the cam contour is machined．DESIGN PROPERTIES OF MATERIALSThe following design properties of materials are defined as they relate to the tensile test．FigureStatic Strength．The strength of a part is the maximum stress that the part can sustain without losing its ability to perform its required function．Thus the static strength may be considered to be approximately equal to the proportional limit，since no plastic deformation takes place and no damage theoretically is done to the material．Stiffness．Stiffness is the deformation-resisting property of a material．The slope of the modulus line and，hence，the modulus of elasticity are measures of the stiffness of a material．Resilience．Resilience is the property of a material that permits it to absorb energy without permanent deformation．The amount of energy absorbed is represented by the area underneath the stress-strain diagram within the elastic region．Toughness．Resilience and toughness are similar properties．However，toughness is the ability to absorb energy without rupture．Thus toughness is represented by the total area underneath the stress-strain diagram，as depicted in Figure 2．8b．Obviously，the toughness and resilience of brittle materials are very low and are approximately equal．Brittleness． A brittle material is one that ruptures before any appreciable plastic deformation takes place．Brittle materials are generally considered undesirable for machine components because they are unable to yield locally at locations of high stress because of geometric stress raisers such as shoulders，holes，notches，or keyways．Ductility． A ductility material exhibits a large amount of plastic deformation prior to rupture．Ductility is measured by the percent of areaand percent elongation of a part loaded to rupture．A 5%elongation at rupture is considered to be the dividing line between ductile and brittle materials．Malleability．M alleability is essentially a measure of the compressive ductility of a material and，as such，is an important characteristic of metals that are to be rolled into sheets．Hardness．The hardness of a material is its ability to resist indentation or scratching．Generally speaking，the harder a material，the more brittle it is and，hence，the less resilient．Also，the ultimate strength of a material is roughly proportional to its hardness．Machinability．Machinability is a measure of the relative ease with which a material can be machined．In general，the harder the material，the more difficult it is to machine．FigureCOMPRESSION AND SHEAR STATIC STRENGTHIn addition to the tensile tests，there are other types of static load testing that provide valuable information．Compression Testing．M ost ductile materials have approximately the same properties in compression as in tension．The ultimate strength，however，can not be evaluated for compression．As a ductile specimen flows plastically in compression，the material bulges out，but there is no physical rupture as is the case in tension．Therefore，a ductile material fails in compression as a result of deformation，not stress．Shear Testing．Shafts，bolts，rivets，and welds are located in such a way that shear stresses are produced．A plot of the tensile test．The ultimate shearing strength is defined as the stress at which failure occurs．The ultimate strength in shear，however，does not equal the ultimate strength in tension．For example，in the case of steel，the ultimate shear strength is approximately 75% of the ultimate strength in tension．This difference must be taken into account when shear stresses are encountered in machine components．DYNAMIC LOADSAn applied force that does not vary in any manner is called a static or steady load．It is also common practice to consider applied forces that seldom vary to be static loads．The force that is gradually applied during a tensile test is therefore a static load．On the other hand，forces that vary frequently in magnitude and direction are called dynamic loads．Dynamic loads can be subdivided to the following three categories．Varying Load．W ith varying loads，the magnitude changes，but the direction does not．For example，the load may produce high and low tensile stresses but no compressive stresses．Reversing Load．In this case，both the magnitude and direction change．These load reversals produce alternately varying tensile and compressive stresses that are commonly referred to as stress reversals．Shock Load．This type of load is due to impact．One example is an elevator dropping on a nest of springs at the bottom of a chute．The resulting maximum spring force can be many times greater than the weight of the elevator，The same type of shock load occurs in automobile springs when a tire hits a bump or hole in the road．FATIGUE FAILURE-THE ENDURANCE LIMIT DIAGRAMThe test specimen in Figure ．，after a given number of stress reversals will experience a crack at the outer surface where the stress is greatest．The initial crack starts where the stress exceeds the strength of the grain on which it acts．This is usually where there is a small surface defect，such as a material flaw or a tiny scratch．As the number of cycles increases，the initial crack begins to propagate into a continuous series of cracks all around the periphery of the shaft．The conception of the initial crack is itself a stress concentration that accelerates the crack propagation phenomenon．Once the entire periphery becomes cracked，the cracks start to move toward the center of the shaft．Finally，when the remaining solid inner area becomes small enough，the stress exceeds the ultimate strength and the shaft suddenly breaks．Inspection of the break reveals a very interesting pattern，as shown in Figure ．The outer annular area is relatively smooth because mating cracked surfaces had rubbed against each other．However，the center portion is rough，indicating a sudden rupture similar to that experienced with the fracture of brittle materials．This brings out an interesting fact．When actual machine parts fail as a result of static loads，they normally deform appreciably because of the ductility of the material．FigureThus many static failures can be avoided by making frequent visual observations and replacing all deformed parts．However，fatigue failures give to warning．Fatigue fail mated that over 90% of broken automobile parts have failed through fatigue．The fatigue strength of a material is its ability to resist the propagation of cracks under stress reversals．Endurance limit is a parameter used to measure the fatigue strength of a material．By definition，the endurance limit is the stress value below which an infinite number of cycles will not cause failure．Let us return our attention to the fatigue testing machine in Figure ．The test is run as follows：A small weight is inserted and the motor is turned on．At failure of the test specimen，the counter registers the number of cycles N，and the corresponding maximum bending stress is calculated from Equation ．The broken specimen is then replaced by an identical one，and an additional weight is inserted to increase the load．A new value of stress is calculated，and the procedure is repeated until failure requires only one complete cycle．A plot is then made of stress versus number of cycles to failure．Figure shows the plot，which is called the endurance limit or S-N curve．Since it would take forever to achieve an infinite number of cycles，1 million cycles is used as a reference．Hence the endurance limit can be found from Figure by noting that it is the stress level below which the material can sustain 1 million cycles without failure．The relationship depicted in Figure is typical for steel，because the curve becomes horizontal as N approaches a very large number．Thus the endurance limit equals the stress level where the curve approaches a horizontal tangent．Owing to the large number of cycles involved，N is usually plotted on a logarithmic scale，as shown in Figure ．When this is done，the endurance limit value can be readily detected by the horizontal straight line．For steel，the endurance limit equals approximately 50% of the ultimate strength．However，if the surface finish is not of polished equality，the value of the endurance limit will be lower．For example，for steel parts with a machined surface finish of 63 microinches ( μin．)，the percentage drops to about 40%．For rough surfaces (300μin．or greater)，the percentage may be as low as 25%．The most common type of fatigue is that due to bending．The next mostfrequent is torsion failure，whereas fatigue due to axial loads occurs very seldom．Spring materials are usually tested by applying variable shear stresses that alternate from zero to a maximum value，simulating the actual stress patterns．In the case of some nonferrous metals，the fatigue curve does not level off as the number of cycles becomes very large．This continuing toward zero stress means that a large number of stress reversals will cause failure regardless of how small the value of stress is．Such a material is said to have no endurance limit．For most nonferrous metals having an endurance limit，the value is about 25% of the ultimate strength．EFFECTS OF TEMPERATURE ON YIELD STRENGTH AND MODULUS OF ELASTICITY Generally speaking，when stating that a material possesses specified values of properties such as modulus of elasticity and yield strength，it is implied that these values exist at room temperature．At low or elevated temperatures，the properties of materials may be drastically different．For example，many metals are more brittle at low temperatures．In addition，the modulus of elasticity and yield strength deteriorate as the temperature increases．Figure shows that the yield strength for mild steel is reduced by about 70% in going from room temperature to 1000o F．Figure shows the reduction in the modulus of elasticity E for mild steel as the temperature increases．As can be seen from the graph，a 30% reduction in modulus of elasticity occurs in going from room temperature to 1000o F．In this figure，we also can see that a part loaded below the proportional limit at room temperature can be permanently deformed under the same load at elevated temperatures．FigureCREEP: A PLASTIC PHENOMENONTemperature effects bring us to a phenomenon called creep，which is the increasing plastic deformation of a part under constant load as a function of time．Creep also occurs at room temperature，but the process is so slow that it rarely becomes significant during the expected life of the temperature is raised to 300o C or more，the increasing plastic deformation can become significant within a relatively short period of time．The creep strength of a material is its ability to resist creep，and creep strength data can be obtained by conducting long-time creep tests simulating actual part operating conditions．During the test，theplastic strain is monitored for given material at specified temperatures．Since creep is a plastic deformation phenomenon，the dimensions of a part experiencing creep are permanently altered．Thus，if a part operates with tight clearances，the design engineer must accurately predict the amount of creep that will occur during the life of the machine．Otherwise，problems such binding or interference can occur．Creep also can be a problem in the case where bolts are used to clamp tow parts together at elevated temperatures．The bolts，under tension，will creep as a function of time．Since the deformation is plastic，loss of clamping force will result in an undesirable loosening of the bolted joint．The extent of this particular phenomenon，called relaxation，can be determined by running appropriate creep strength tests．Figure shows typical creep curves for three samples of a mild steel part under a constant tensile load．Notice that for the high-temperature case the creep tends to accelerate until the part fails．The time line in the graph (the x-axis) may represent a period of 10 years，the anticipated life of the product．FigureSUMMARYThe machine designer must understand the purpose of the static tensile strength test．This test determines a number of mechanical properties of metals that are used in design equations．Such terms as modulus of elasticity，proportional limit，yield strength，ultimate strength，resilience，and ductility define properties that can be determined from the tensile test．Dynamic loads are those which vary in magnitude and direction and may require an investigation of the machine part’s resistance to failure．Stress reversals may require that the allowable design stress be based on the endurance limit of the material rather than on the yield strength or ultimate strength．Stress concentration occurs at locations where a machine part changes size，such as a hole in a flat plate or a sudden change in width of a flat plate or a groove or fillet on a circular shaft．Note that for the case of a hole in a flat or bar，the value of the maximum stress becomes much larger in relation to the average stress as the size of the hole decreases．Methods of reducing the effect of stress concentration usuallyinvolve making the shape change more gradual．Machine parts are designed to operate at some allowable stress below the yield strength or ultimate strength．This approach is used to take care of such unknown factors as material property variations and residual stresses produced during manufacture and the fact that the equations used may be approximate rather that exact．The factor of safety is applied to the yield strength or the ultimate strength to determine the allowable stress．Temperature can affect the mechanical properties of metals．Increases in temperature may cause a metal to expand and creep and may reduce its yield strength and its modulus of elasticity．If most metals are not allowed to expand or contract with a change in temperature，then stresses are set up that may be added to the stresses from the load．This phenomenon is useful in assembling parts by means of interference fits．A hub or ring has an inside diameter slightly smaller than the mating shaft or post．The hub is then heated so that it expands enough to slip over the shaft．When it cools，it exerts a pressure on the shaft resulting in a strong frictional force that prevents loosening．TYPES OF CAM CONFIGURATIONSPlate Cams．This type of cam is the most popular type because it is easy to design and manufacture．Figure 6．1 shows a plate cam．Notice that the follower moves perpendicular to the axis of rotation of the camshaft．All cams operate on the principle that no two objects can occupy the same space at the same time．Thus，as the cam rotates ( in this case，counterclockwise )，the follower must either move upward or bind inside the guide．We will focus our attention on the prevention of binding and attainment of the desired output follower motion．The spring is required to maintain contact between the roller of the follower and the cam contour when the follower is moving downward．The roller is used to reduce friction and hence wear at the contact surface．For each revolution of the cam，the follower moves through two strokes-bottom dead center to top dead center (BDC to TDC) and TDC to BDC．Figure illustrates a plate cam with a pointed follower．Complex motions can be produced with this type of follower because the point can follow precisely any sudden changes in cam contour．However，this design is limited to applications in which the loads are very light；otherwisethe contact point of both members will wear prematurely，with subsequent failure．Two additional variations of the plate cam are the pivoted follower and the offset sliding follower，which are illustrated in Figure ．A pivoted follower is used when rotary output motion is desired．Referring to the offset follower，note that the amount of offset used depends on such parameters as pressure angle and cam profile flatness，which will be covered later．A follower that has no offset is called an in-line follower．Figure 6..3Translation Cams．Figure depicts a translation cam．The follower slides up and down as the cam translates motion in the horizontal direction．Note that a pivoted follower can be used as well as a sliding-type follower．This type of action is used in certain production machines in which the pattern of the product is used as the cam．A variation on this design would be a three-dimensional cam that rotates as well as translates．For example，a hand-constructed rifle stock is placed in a special lathe．This stock is the pattern，and it performs the function of a cam．As it rotates and translates，the follower controls a tool bit that machines the production stock from a block of wood．FigurePositive-Motion Cams．In the foregoing cam designs，the contact between the cam and the follower is ensured by the action of the spring forces during the return stroke．However，in high-speed cams，the spring force required to maintain contact may become excessive when added to the dynamic forces generated as a result of accelerations．This situation can result in unacceptably large stress at the contact surface，which in turn can result in premature wear．Positive-motion cams require no spring because the follower is forced to contact the cam in two directions．Thereare four basic types of positive-motion cams: the cylindrical cam，the grooved-plate cam ( also called a face cam ) ，the matched-plate cam，and the scotch yoke cam．Cylindrical Cam．The cylindrical cam shown in Figure produces reciprocating follower motion，whereas the one shown in Figure illustrates the application of a pivoted follower．The cam groove can be designed such that several camshaft revolutions are required to produce one complete follower cycle．Grooved-plate Cam．In Figure we see a matched-plate cam with a pivoted follower，although the design also can be used with a translation follower．Cams E and F rotate together about the camshaft B．Cam E is always in contact with roller C，while cam F maintains contact with roller D．Rollers C and D are mounted on a bell-crank lever，which is the follower oscillating about point A．Cam E is designed to provide the desired motion of roller C，while cam F provides the desired motion of roller D．Scotch Yoke Cam．This type of cam，which is depicted in Figure ，consists of a circular cam mounted eccentrically on its camshaft．The stroke of the follower equals two times the eccentricity e of the cam．This cam produces simple harmonic motion with no dwell times．Refer to Section for further discussion．CAM TERMINOLOGYBefore we become involved with the design of cams，it is desirable to know the various terms used to identify important cam design parameters．The following terms refer to Figure ．The descriptions will be more understandable if you visualize the cam as stationary and the follower as moving around the cam．Trace Point．The end point of a knife-edge follower or the center of the roller of a roller-type follower．Cam Contour．The actual shape of the cam．Base Circle．The smallest circle that can be drawn tangent to the cam contour．Its center is also the center of the camshaft．The smallest radial size of the cam stars at the base circle．Pitch Curve．The path of the trace point，assuming the cam is stationary and the follower rotates about the cam．Prime Circle．The smallest circle that can be drawn tangent to the pitch curve．Its center is also the center of the camshaft．Pressure Angle．The angle between the direction of motion of the follower and the normal to the pitch curve at the point where the center of the roller lies．Cam Profile．Same as cam contour．BDC．Bottom Dead Center，the position of the follower at its closest point to the cam hub．Stroke．The displacement of the follower in its travel between BDC and TDC．Rise．The displacement of the follower as it travels from BDC to TDC．Return．The displacement of the follower as it travels from TDC or BDC．Ewell．The action of the follower when it remains at a constant distance from the cam hub while the cam turns．A clearer understanding of the significance of the pressure angle can be gained by referring to Figure ．Here FTis the total force acting on the roller．It must be normal to the surfaces at the contact point．Its direction is obviously not parallel to the direction of motion of the follower．Instead，it is indicated by the angle α，the pressure angle，measured from the line representing the direction of motion of thefollower．Therefore，the force FT has a horizontal component FHand avertical component FV．The vertical component is the one that drives thefollower upward and，therefore，neglecting guide friction，equals thefollower Fload．The horizontal component has no useful purpose but it is unavoidable．In fact，it attempts to bend the follower about its guide．This can damage the follower or cause it to bind inside its guide．Obviously，we want the pressure angle to be as possible to minimize the side thrustFH．A practical rule of thumb is to design the cam contour so that the pressure angle does not exceed 30o．The pressure angle，in general，depends on the following four parameters:——Size of base circle——Amount of offset of follower——Size of roller——Flatness of cam contour ( which depends on follower stroke and type of follower motion used )Some of the preceding parameters cannot be changed without altering the cam requirements，such as space limitations．After we have learned how to design a cam，we will discuss the various methods available to reducethe pressure angle．故障的分析、尺寸的决定以及凸轮的分析和应用前言介绍：作为一名设计工程师有必要知道零件如何发生和为什么会发生故障，以便通过进行最低限度的维修以保证机器的可靠性。

机床刀具设计机械类毕业设计外文文献翻译中英文翻译

英语原文：Design Of Tool Machine PropResearch significanceThe original knife machine control procedures are designed individually, not used tool management system, features a single comparison, the knife only has to find the tool knife, knife positioning the shortest path, axis tool change, but does not support large-scale tool.Automatic knife in the knife election, in the computer memory knife-election on the basis of using the Siemens 840 D features, and the election procedures knife more concise, and complete the space Daotao View. ATC use the knife rapid completion of STEP-7 programming, and have been tested in practice. In the positioning of the knife, PLC controlled modular design method, which future production of similar machines will be very beneficial, it is easy to use its other machine. Automatic tool change systems will be faster growth, reduced tool change time, increase the positioning accuracy tool is an important means to help NC technology development.Tool and inventory components of modern production is an important link in the management, especially for large workshop management. The traditional way of account management, and low efficiency, high error rate, and not sharing information and data, tools and the use of state can not track the life cycle, are unable to meet the current information management needs. With actual production, we have to establish a workshop tool for the three-dimensional tool storage system to meet the knife workshop with auxiliary storage and management needs.The system uses optimization technology, a large number of computer storage inventory information, timely, accurate, and comprehensive tool to reflect the inventory situation. The entire system uses a graphical interface, man-machine dialogue tips from the Chinese menu, select various functions can be realized and the importation of all kinds of information. Management system using online help function. Through the workshop management, network management and sharing of information. Have automated inventory management, warehousing management tool, a tool for the management and statistical functions.1.System components and control structureThe entire system, including the structure and electrical machinery control systems.1.1.1Mechanical structure and working principleTool from the stent, drive, drive system, Turret, shielding, control system, and electrical components. Support from the column, beam, the upper and lower guide Central track, and track support component.1) Drive for the system chosen VVVF method. Cone used brake motors, with VVVF by Cycloidreducer through sprocket drive.2) Drag a variable frequency drive system and control technology. VVVF adopted, will speed drive shaft in the normal range adjustment to control the speed rotary turret to 5 ~ 30mm in, the drive shaft into two, two under through sprocket, the two profiled rollers Chain driven rotating shelves. Expansion chain adopted by the thread tight regulation swelling, swelling the regular way. - Conditioned, under the same chain-of-conditioning, so that the chain of uniform.3) Turret and shields the entire total of 14 independent Turret. 13 of them as a socket-Turret, as a drawer-Turret, each Turret back through the pin and, under the conveyor chain link chain plate, installed at the bottom roller, chain driven rotating turret rotation along the track. Outlet-Turret and BT50-BT40 Turret Turret two kinds of forms. To strengthen management, security, landscaping modeling, shelf peripherals and shields. Turret-drawer drawer placed at six other Des V oeux a knife, can be categorized with some of knife auxiliary equipment, such as bits, such as turning tools.1.1.2.Electrical Control SystemThis tool storage systems is the main electrical control their shelves for operational control and position control. Operational control equipment, including operation of the start of braking control. Position Control is the main location and address of the shelves for testing. Control system as shown in Figure 1.图 1 Tool Control System for the1) Electric Transmission horizontal rotary tool storage systems are the mechanical movements are repeated short-term work system. And the run-time system needs some speed, speed transmission needs, the system will use VVVF method can be used simple structure, reliable operation of the motor and frequency inverter.2) Control of the system is divided into two kinds of manual control and automatic control, manual control as a general reserve and debugging methods of work; ways to the system control computer (IPC) and the control unit (inverter contactor , etc.) consisting of a control system.3) location and positioning accuracy of the system automatically identify the site and location using a detection device as proximity switches, relays through the plate-point isolation and the number plate recorded close to the switching signal acquisition and operation of Hutchison with a Optimal Path addressable identify the current location and shelves of the purpose of the shelf location. In order to enable a more accurate positioning system, adopted two photoelectric switches, to detect the two shelves of the two films.1.2.The functions of the knifeknife The is the role of reserves a certain number of tools, machine tool spindle in hand to achieve the fungibility a disc cutter knife is the type of library, the chain knives, and other means, in the form of the knife and capacity according to the Machine Tool to determine the scope of the process.mon typesThe knife is a tool storage devices, the common knife mainly in the following forms:(1) the turret knifeIncluding the first level turret vertical turret and the first two, see Figure 2.6 a) and b):(2) the disc cutterDisc knife in the library with discoid knife, cutting tool along See how vertical arrangement (including radial and axial from knife from knife), along See how radial array into acute or arranged in the form of the knife. Simple, compact, more applications, but are ring-cutter, low utilization of space. Figure 2.7 a) to c). If the knife storage capacity must be increased to increase the diameter of the knife, then the moment of inertia also increased correspondingly, the election campaign long knife. Tool number not more than 32 general. Cutter was multi-loop order of the space utilization knife, but inevitably given the knife from complex institutions,applicable to the restricted space Machine Tool storage capacity and more occasions. Two-disc structure is two smaller capacity knife on both sides of the sub-spindle place, more compactlayout, the number of certificates corresponding increase knife, apply to small and medium-sized processing center.(3) the chain knifeIncluding single-and multi-ring chain ring chain, chain link can take many forms change, see Figure 2.8 a) to c), thebasic structure shown inFigure 2. 8 doFeatures: knife apply tothe larger capacity of theoccasion, the space of thesmall number ofgenerally applicable tothe tool in the 30-120.Only increase the lengthof the chain tool will increase the number should not be increased circumferential speed of itsmoment of inertia of the knife does not increase the disc as large.(4) linear combination knife and the knife libraryThe linear knife simple structure in Figure 2.9, tool single order, the capacity of small knife, used for CNC lathe and drill press on. Because the location of fixed knife, ATC completed action by the spindle without manipulator. The cutter knife is generally the turret combination turret with a combination of the disc cutter knife and the chain combination. Every single knife the knife certificates of smaller, faster tool change. There are also some intensive drum wheel, and the lattice-type magazine for the knife, the knife-intensive though. Small footprint, but because of structural constraints, basically not used for single processing center, the concentration used for FMS for the knife system.1.4 Tool storage capacityTool storage capacity of the first to consider the needs of processing, from the use of point of view, generally 10 to 40 knives, knife will be the utilization of the high, and the structure iscompact.1.5 Tool options(1) choose to order processing tool according to the order, followed Add to the knife every knife in the Block. Each tool change, the order of rotation of a cutter knife on location, and remove the need knives, has been used by the cutter knife can be returned to the original Block, can also order Add Block, a knife. However, as the knife in the tool in different processes can not be repeated use of the knife must increase the capacity and lower utilization rate.(2) most of the arbitrary choice of the current system of using arbitrary NC election knives, divided into Daotao coding, coding and memory-cutter, three. Daotao coding tool code or knives or Daotao need to install the code used to identify, in accordance with the general principle of binary coding coding. Tool knife election coding method uses a special knife handle structure, and each of the coding tool. Each of the tool has its own code, thereby cutting tool can be in different processes repeatedly used, not to replace the tool back at the original knife, the knife capacity can be reduced accordingly. Memory-election this paper knife, in this way can knives and knife in the position corresponding to the Daotao memory of the PLC in the NC system, no matter which tool on the Inner knife, tool information is always there in mind, PLC . On the knife with position detection devices, will be the location of each Daotao. This tool can be removed and sent back to arbitrary. On the knife is also a mechanical origin, every election, the nearest knife selection.1.6.Control of the knife(1) the knife as a system to control the positioning axis. In the ladder diagram in accordance with the instructions for computing T code comparison of the output angle and speed of instructions to the knife the knife servo drive servo motor. Tool storage capacity, rotation speed, and / deceleration time, and other system parameters can be set in such a manner free from any outside influence positioning accurate and reliable but the cost is higher.(2) knife from the hydraulic motor drives, fast / slow the points, with proximity switches count and positioning. In comparison ladder diagram of the current storage system knife (knife spindle) and goals knife (pre-knife) and computing, then output rotation instructions, judging by the shortest path rotation in place. This approach requires sufficient hydraulic power and electromagnetic valve knife the rotational speed can be adjusted through the throttle. But over time may be oily hydraulic, oil temperature and environmental factors impact the change in velocity and accuracy. Not generally used in large and medium-sized machine tool change frequently.(3) the knife from AC asynchronous motor driven cam mechanism (Markov institutions), with proximity switches count, which means stable operation, and generally accurate and reliablepositioning cam used in conjunction with a mechanical hand, A TC fast-positioning.2. ATC, the main types, characteristics, and the scope of application 2.1 Auto Rotary ToolRotary Tool automatically onthe use of CNC machine tool is asimple installation of automatic toolchange, the Quartet and 47.60 TurretTool various forms, such as rotaryturret were installed on four, six ormore of the Tool , NC instructions byATC. Rotary Tool has two verticaland horizontal, relatively simplestructure, applicable to economicCNC lathe.Rotary Tool in the structure musthave good strength and stiffness,resistance to bear rough Cutting Toolin the cutting force and reduce therole of deformation and improveprocessing accuracy. Rotating Toolto choose reliable positioningprogramme structure and reasonable position, in order to ensure that each rotary turret to a higher position after repeated positioning accuracy (typically 0.001 to 0.005mm). Figure 2.1 shows the spiral movements of the Quartet Turret.Auto Rotary Tool in the simplest of ATC, is 180 º rotary ATC devices, as shown in Figure 2.2 ATC instructions received, the machine control system put ATC spindle control to the designated location at the same time, the tool movement to the appropriate location, ATC, with the rotary axis and at the same time, the knives matching tool; drawbars from Spindle Cutting Tools rip, ATC, will be the tool from their position removed; ATC, 180 º rotary tool spindle and the tool and tool away; A TC, the Rotary At the same time, the tool refocusing its position to accept Spindle removed from the cutting tool; Next, ATC, will be replaced with the cutter knives were unloaded into the spindle and tool: Finally, back to the original ATC, "standby" position. At this point, ATC completed procedures to continue to run. This ATC, the main advantage ofsimple structure, the less movement, fast tool change. The main disadvantage is that knives must be kept in parallel with the axis of the plane, and after the home side compared to the tool, chip and liquid-cutting knife into the folder, it is necessary to the tool plus protection. Cone knife folder on the chip will cause A TC error, or even damage knife folders, and the possibility of spindle. Some processing centre at the transfer, and the tool side. When the ATC command is called, the transfer-cutter knives will be removed, the machine go forward, and positioning with the ATC, in line with the position. 180 º "Rotary ATC devices can be used horizontal machine, can also be used for vertical machining centers.2. 2 ATC head-turret installedWith rotating CNC machine tool often used such ATC devices, with a few turret head spindle, each with a spindle on both knives, the first tower interim process can be automatic tool change-realization. The advantage is simple structure, tool change time is short, only about 2 s. However, due to spatial constraints, the number of spindle can not be too much, usually only apply to processes less, not to high precision machine tools, such as the NC drill, such as CNC milling machine. In recent years there has been a mechanical hand and the turret head with a knife for the automatic tool change ATC devices, as shown in Figure 2.3. It is in fact a turret head ATC, and the knife-ATC device combination. The principle is as follows:5 turret on the first two tool spindle 3 and 4, when using the tool spindle 4 processing tool, the manipulator 2 will be the next step to the need for the tool does not work on the tool spindle 3 until after the completion of this process , the first rotary turret 180 º, A TC completed. ATC most of their time and processing time coincidence, the only real tool change time turret transposition of the first time, this approach mainly used for ATC and NC NC drilling file bed. 2. 3.Daidao system for the automatic tool changeFigure 2.4 shows the knife and the whole machine tool CNC machine tools for the appearance of Fig.Figure 2.5 shows the knife and split-type machine to the appearance of CNC machine tool plans.At this point, knife storage capacity, a heavier tool can, and often additional transport unit to complete the knife between the spindle and cutting tool transport.Daidao the knife from the ATC, the election knives, automatic loading and unloading machine tool and tool exchange institutions (manipulator), composed of four parts, used widely.Tool Automatic Tool Change the manipulator system, the whole process more complicated ATC. We must first used in the processing of all installed in the standard tool on the knife handle in the machine outside the pre-size, according to a certain way Add to the knife. ATC, selected first in the knife knife, and then from ATC, from the knife from the knife or spindle, exchange, the new knife into the spindle, the old knife back into the knife.ATC, as the former two knives to accommodate a limited number can not be too many, can notmeet the needs of complex parts machining, CNC machine tool Automatic Tool Change Daidao the use of the automatic tool change devices. The knife has more capacity, both installed in the spindle box side or above. As for the automatic tool change Daidao device CNC machine tool spindle box only a spindle, spindle components to high stiffness to meet the machining requirements. The number of establishments in larger knife, which can meet the more complex parts of the machining processes, significantly improving productivity. Daidao system for the automatic tool change applied to drilling centres and CNC machining centers. The comparison drawn Daidao automatic tool change system is the most promising.3.PLC control of the knife random mode of election3. 1Common methods of automatic election knifeAutomatic control of the knife CNC refers to the system after the implementation of user instructions on the knife library automation process, including the process to find knives and automatic tool change [(63,71]. CNC Machining Center device (CNC) directive issued by the election knife , a knife, the tool required to take the knife position, said the election automatic knife. automatically elected knife There are two ways: random sequence election knives and knife election method.3.1.1 order election knifeTool Selection order is the process tool according to the sequence of the insert knife, the use of knives in order to take place, used knives back at the original knife, can also order Add Block, a knife. In this way, no need Tool identification devices, and drive control is a relatively simple, reliable and can be used directly from the points of the knife machinery to achieve. But the knives in each of the tool in different processes can not be reused, if the tool is installed in accordance with the order of the knife, there will be serious consequences. The need to increase the number of knives and knife the capacity of the tool and reduce the utilization of the knife.3.1.2Random election knifeRandom election under the knife is arbitrary instructions to select the required tools, then there must be tool identification devices. Tool knife in the library do not have the processing in accordance with the order of the workpiece can be arbitrary storage. Each of the tool (or knifeblocks) are for a code, automatic tool change, the rotary cutter, every tool have been the "tool identification device" acceptable identification. When CNC tool code and the code in line with directives of the tool selected, the rotary cutter knives will be sent to the ATC position, waiting to grab manipulator. Random knife election is the advantage of the cutter knife in the order has nothing to do with the processing sequence, the same tool can be used repeatedly. Therefore, the relatively small number of knives, knife the corresponding smaller. Random elections knife on the tool must be coded to identify. There are three main coding.1. Tool coding. Adopt special knife handle structure coding, the drawbars on the knife handle back-end packages such as spacing of the coding part of the lock-nut fixed. Coding diameter ring diameter of a size two, respectively, said that binary "1" and "0" to the two rings are different, can be a series of code. For example, there are six small diameter of the ring can be made to distinguish between 63 (26-1 = 63) of the coding tool. All of 0 normally not allowed to use the code, to avoid the cutter knife Block did not confuse the situation.2. Knife Block coding. On the knife Block coding, coding tool, and tool into line with the number of knives in the Block. ATC knife when the rotation, so that each knife seats followed through knowledge knife, knife found blocks, knives stopped the rotation. At this time there is no knife handle encoding part of the knife handle simplified.3. Annex coding methods. This style of coding keys, coded cards, coding and coding-disc, which is the most widely used coding keys.First to knives are attached to a tool of the show wrapped coding keys, and when the cutter knife to the store at knife in, so put the number of keys to remember knife Block Road, will be inserted into key to the coding Block next to the key hole in the seat for the knife to the numbers.ConclusionFocused on in today's manufacturing environment tool storage and management of new models and methods, practical application of good results in systems integration and optimization, and other aspects of operations will be further explored, so that it has a higher theoretical and practical level.译文：机床刀具设计课题研究意义机床原来的刀库控制程序是单独设计的，没有采用刀具管理系统，功能也比较单一，只实现了刀库刀具的找刀、刀库最短路径定位、主轴换刀，而且不支持大型刀具。

机械类毕业设计外文翻译

本科毕业论文(设计)外文翻译学院：机电工程学院专业：机械工程及自动化姓名：高峰指导教师：李延胜2011年 05 月 10日教育部办公厅Failure Analysis，Dimensional Determination And Analysis，Applications OfCamsINTRODUCTIONIt is absolutely essential that a design engineer know how and why parts fail so that reliable machines that require minimum maintenance can be designed．Sometimes a failure can be serious，such as when a tire blows outon an automobile traveling at high speed．On the other hand，a failure may be no more than a nuisance．An example is the loosening of the radiator hose in an automobile cooling system．The consequence of this latter failure is usually the loss of some radiator coolant，a condition that is readily detected and corrected．The type of load a part absorbs is just as significant as the magnitude．Generally speaking，dynamic loads with direction reversals cause greater difficulty than static loads，and therefore，fatigue strength must be considered．Another concern is whether the material is ductile or brittle．For example，brittle materials are considered to be unacceptable where fatigue is involved．Many people mistakingly interpret the word failure to mean the actual breakage of a part．However，a design engineer must consider a broader understanding of what appreciable deformation occurs．A ductile material，however will deform a large amount prior to rupture．Excessive deformation，without fracture，may cause a machine to fail because the deformed part interferes with a moving second part．Therefore，a part fails(even if it has not physically broken)whenever it no longer fulfills its required function．Sometimes failure may be due to abnormal friction or vibration between two mating parts．Failure also may be due to a phenomenon called creep，which is the plastic flow of a material under load at elevated temperatures．In addition，the actual shape of a part may be responsiblefor failure．For example，stress concentrations due to sudden changes in contour must be taken into account．Evaluation of stress considerations is especially important when there are dynamic loads with direction reversals and the material is not very ductile．In general，the design engineer must consider all possible modes of failure，which include the following．——Stress——Deformation——Wear——Corrosion——Vibration——Environmental damage——Loosening of fastening devicesThe part sizes and shapes selected also must take into account many dimensional factors that produce external load effects，such as geometricdiscontinuities，residual stresses due to forming of desired contours，and the application of interference fit joints．Cams are among the most versatile mechanisms available．A cam is a simple two-member device．The input member is the cam itself，while the output member is called the follower．Through the use of cams，a simple input motion can be modified into almost any conceivable output motion that is desired．Some of the common applications of cams are——Camshaft and distributor shaft of automotive engine——Production machine tools——Automatic record players——Printing machines——Automatic washing machines——Automatic dishwashersThe contour of high-speed cams (cam speed in excess of 1000 rpm) must be determined mathematically．However，the vast majority of cams operate at low speeds(less than 500 rpm) or medium-speed cams can be determinedgraphically using a large-scale layout．In general，the greater the cam speed and output load，the greater must be the precision with which the cam contour is machined．DESIGN PROPERTIES OF MATERIALSThe following design properties of materials are defined as they relate to the tensile test．Figure 2.7Static Strength．The strength of a part is the maximum stress that the part can sustain without losing its ability to perform its required function．Thus the static strength may be considered to be approximately equal to the proportional limit，since no plastic deformation takes place and no damage theoretically is done to the material．Stiffness．Stiffness is the deformation-resisting property of a material．The slope of the modulus line and，hence，the modulus of elasticity are measures of the stiffness of a material．Resilience．Resilience is the property of a material that permits it to absorb energy without permanent deformation．The amount of energy absorbed is represented by the area underneath the stress-strain diagram within theelastic region．Toughness．Resilience and toughness are similar properties．However，toughness is the ability to absorb energy without rupture．Thus toughness is represented by the total area underneath the stress-strain diagram， as depicted in Figure 2．8b．Obviously，the toughness and resilience of brittle materials are very low and are approximately equal．Brittleness． A brittle material is one that ruptures before any appreciable plastic deformation takes place．Brittle materials are generally considered undesirable for machine components because they are unable to yield locally at locations of high stress because of geometric stress raisers such as shoulders，holes，notches，or keyways．Ductility． A ductility material exhibits a large amount of plastic deformation prior to rupture．Ductility is measured by the percent of area and percent elongation of a part loaded to rupture．A 5%elongation at rupture is considered to be the dividing line between ductile and brittle materials．Malleability．M alleability is essentially a measure of the compressive ductility of a material and，as such，is an important characteristic of metals that are to be rolled into sheets．Hardness．The hardness of a material is its ability to resistindentation or scratching．Generally speaking，the harder a material，the more brittle it is and，hence，the less resilient．Also，the ultimate strength of a material is roughly proportional to its hardness．Machinability．Machinability is a measure of the relative ease with which a material can be machined．In general，the harder the material，the more difficult it is to machine．Figure 2.8COMPRESSION AND SHEAR STATIC STRENGTHIn addition to the tensile tests，there are other types of static load testing that provide valuable information．Compression Testing．M ost ductile materials have approximately the same properties in compression as in tension．The ultimate strength，however，can not be evaluated for compression．As a ductile specimen flows plastically in compression，the material bulges out，but there is no physical rupture as is the case in tension．Therefore，a ductile material fails in compression as a result of deformation，not stress．Shear Testing．Shafts，bolts，rivets，and welds are located in such a way that shear stresses are produced．A plot of the tensile test．The ultimateshearing strength is defined as the stress at which failure occurs．The ultimate strength in shear，however，does not equal the ultimate strength in tension．For example，in the case of steel，the ultimate shear strength is approximately 75% of the ultimate strength in tension．This difference must be taken into account when shear stresses are encountered in machine components．DYNAMIC LOADSAn applied force that does not vary in any manner is called a static or steady load．It is also common practice to consider applied forces that seldom vary to be static loads．The force that is gradually applied during a tensile test is therefore a static load．On the other hand，forces that vary frequently in magnitude and direction are called dynamic loads．Dynamic loads can be subdivided to the following three categories．Varying Load．W ith varying loads，the magnitude changes，but the direction does not．For example，the load may produce high and low tensile stresses but no compressive stresses．Reversing Load．In this case，both the magnitude and direction change．These load reversals produce alternately varying tensile andcompressive stresses that are commonly referred to as stress reversals．Shock Load．This type of load is due to impact．One example is an elevator dropping on a nest of springs at the bottom of a chute．The resulting maximum spring force can be many times greater than the weight of the elevator，The same type of shock load occurs in automobile springs when a tire hits a bump or hole in the road．FATIGUE FAILURE-THE ENDURANCE LIMIT DIAGRAMThe test specimen in Figure 2.10a．，after a given number of stress reversals will experience a crack at the outer surface where the stress is greatest．The initial crack starts where the stress exceeds the strength of the grain on which it acts．This is usually where there is a small surface defect，such as a material flaw or a tiny scratch．As the number of cycles increases，the initial crack begins to propagate into a continuous series of cracks all around the periphery of the shaft．The conception of the initial crack is itself a stress concentration that accelerates the crack propagation phenomenon．Once the entire periphery becomes cracked，the cracks start to move toward the center of the shaft．Finally，when the remaining solid inner area becomes small enough，the stress exceeds the ultimate strength and the shaft suddenly breaks．Inspection of the break reveals a very interesting pattern，as shown in Figure 2.13．The outer annular area is relatively smooth because mating cracked surfaces had rubbed againsteach other．However，the center portion is rough，indicating a sudden rupture similar to that experienced with the fracture of brittle materials．This brings out an interesting fact．When actual machine parts fail as a result of static loads，they normally deform appreciably because of the ductility of the material．Figure 2.13Thus many static failures can be avoided by making frequent visual observations and replacing all deformed parts．However，fatigue failures give to warning．Fatigue fail mated that over 90% of broken automobile parts have failed through fatigue．The fatigue strength of a material is its ability to resist the propagation of cracks under stress reversals．Endurance limit is a parameter used to measure the fatigue strength of a material．By definition，the endurance limit is the stress value below which an infinite number of cycles will not cause failure．Let us return our attention to the fatigue testing machine in Figure 2.9．The test is run as follows：A small weight is inserted and the motor is turned on．At failure of the test specimen，the counter registers the number of cycles N，and the corresponding maximum bending stress iscalculated from Equation 2.5．The broken specimen is then replaced by an identical one，and an additional weight is inserted to increase the load．A new value of stress is calculated，and the procedure is repeated until failure requires only one complete cycle．A plot is then made of stress versus number of cycles to failure．Figure 2.14a shows the plot，which is called the endurance limit or S-N curve．Since it would take forever to achieve an infinite number of cycles，1 million cycles is used as a reference．Hence the endurance limit can be found from Figure 2.14a by noting that it is the stress level below which the material can sustain 1 million cycles without failure．The relationship depicted in Figure 2.14 is typical for steel，because the curve becomes horizontal as N approaches a very large number．Thus the endurance limit equals the stress level where the curve approaches a horizontal tangent．Owing to the large number of cycles involved，N is usually plotted on a logarithmic scale，as shown in Figure 2.14b．When this is done，the endurance limit value can be readily detected by the horizontal straight line．For steel，the endurance limit equals approximately 50% of the ultimate strength．However，if the surface finish is not of polished equality，the value of the endurance limit will be lower．For example，for steel parts with a machined surface finish of 63 micr oinches ( μin．)，the percentage drops to about 40%．For rough surfaces (300μin．or greater)，the percentage may be as low as 25%．The most common type of fatigue is that due to bending．The next most frequent is torsion failure，whereas fatigue due to axial loads occurs very seldom．Spring materials are usually tested by applying variable shear stresses that alternate from zero to a maximum value，simulating the actual stress patterns．In the case of some nonferrous metals，the fatigue curve does not level off as the number of cycles becomes very large．This continuing toward zero stress means that a large number of stress reversals will cause failure regardless of how small the value of stress is．Such a material is said to have no endurance limit．For most nonferrous metals having an endurance limit，the value is about 25% of the ultimate strength．EFFECTS OF TEMPERATURE ON YIELD STRENGTH AND MODULUS OF ELASTICITYGenerally speaking，when stating that a material possesses specified values of properties such as modulus of elasticity and yield strength，it is implied that these values exist at room temperature．At low or elevated temperatures，the properties of materials may be drastically different．For example，many metals are more brittle at low temperatures．In addition，the modulus of elasticity and yield strength deteriorate as the temperature increases．Figure 2.23 shows that the yield strength for mild steel is reduced by about 70% in going from room temperature to 1000o F．Figure 2.24 shows the reduction in the modulus of elasticity E for mild steel as the temperature increases．As can be seen from the graph，a 30% reduction in modulus of elasticity occurs in going from room temperature to 1000o F．In this figure，we also can see that a part loaded below the proportional limit at room temperature can be permanently deformed under the same load at elevated temperatures．Figure 2.24CREEP: A PLASTIC PHENOMENONTemperature effects bring us to a phenomenon called creep，which is the increasing plastic deformation of a part under constant load as a function of time．Creep also occurs at room temperature，but the process is so slow that it rarely becomes significant during the expected life of the temperature is raised to 300o C or more，the increasing plastic deformation can become significant within a relatively short period of time．The creep strength of a material is its ability to resist creep，and creep strength data can be obtained by conducting long-time creep tests simulating actual part operating conditions．During the test，the plastic strain is monitored for given material at specified temperatures．Since creep is a plastic deformation phenomenon，the dimensions of a part experiencing creep are permanently altered．Thus，if a part operateswith tight clearances，the design engineer must accurately predict the amount of creep that will occur during the life of the machine．Otherwise，problems such binding or interference can occur．Creep also can be a problem in the case where bolts are used to clamp tow parts together at elevated temperatures．The bolts，under tension，will creep as a function of time．Since the deformation is plastic，loss of clamping force will result in an undesirable loosening of the bolted joint．The extent of this particular phenomenon，called relaxation，can be determined by running appropriate creep strength tests．Figure 2.25 shows typical creep curves for three samples of a mild steel part under a constant tensile load．Notice that for the high-temperature case the creep tends to accelerate until the part fails．The time line in the graph (the x-axis) may represent a period of 10 years，the anticipated life of the product．Figure 2.25SUMMARYThe machine designer must understand the purpose of the static tensile strength test．This test determines a number of mechanical properties of metals that are used in design equations．Such terms as modulus ofelasticity，proportional limit，yield strength，ultimate strength，resilience，and ductility define properties that can be determined from the tensile test．Dynamic loads are those which vary in magnitude and direction and may require an investigation of the machine part’s resistance to failure．Stress reversals may require that the allowable design stress be based on the endurance limit of the material rather than on the yield strength or ultimate strength．Stress concentration occurs at locations where a machine part changes size，such as a hole in a flat plate or a sudden change in width of a flat plate or a groove or fillet on a circular shaft．Note that for the case of a hole in a flat or bar，the value of the maximum stress becomes much larger in relation to the average stress as the size of the hole decreases．Methods of reducing the effect of stress concentration usually involve making the shape change more gradual．Machine parts are designed to operate at some allowable stress below the yield strength or ultimate strength．This approach is used to take care of such unknown factors as material property variations and residual stresses produced during manufacture and the fact that the equations used may be approximate rather that exact．The factor of safety is applied to the yield strength or the ultimate strength to determine the allowablestress．Temperature can affect the mechanical properties of metals．Increases in temperature may cause a metal to expand and creep and may reduce its yield strength and its modulus of elasticity．If most metals are not allowed to expand or contract with a change in temperature，then stresses are set up that may be added to the stresses from the load．This phenomenon is useful in assembling parts by means of interference fits．A hub or ring has an inside diameter slightly smaller than the mating shaft or post．The hub is then heated so that it expands enough to slip over the shaft．When it cools，it exerts a pressure on the shaft resulting in a strong frictional force that prevents loosening．TYPES OF CAM CONFIGURATIONSPlate Cams．This type of cam is the most popular type because it is easy to design and manufacture．Figure 6．1 shows a plate cam．Notice that the follower moves perpendicular to the axis of rotation of the camshaft．All cams operate on the principle that no two objects can occupy the same space at the same time．Thus，as the cam rotates ( in this case，counterclockwise )，the follower must either move upward or bind inside the guide．We will focus our attention on the prevention of binding and attainment of the desired output follower motion．The spring is required to maintain contact between the roller of the follower and the cam contour when the follower is movingdownward．The roller is used to reduce friction and hence wear at the contact surface．For each revolution of the cam，the follower moves through two strokes-bottom dead center to top dead center (BDC to TDC) and TDC to BDC．Figure 6.2 illustrates a plate cam with a pointed follower．Complex motions can be produced with this type of follower because the point can follow precisely any sudden changes in cam contour．However，this design is limited to applications in which the loads are very light；otherwise the contact point of both members will wear prematurely，with subsequent failure．Two additional variations of the plate cam are the pivoted follower and the offset sliding follower，which are illustrated in Figure 6.3．A pivoted follower is used when rotary output motion is desired．Referring to the offset follower，note that the amount of offset used depends on such parameters as pressure angle and cam profile flatness，which will be covered later．A follower that has no offset is called an in-line follower．Figure 6..3Translation Cams．Figure 6.4 depicts a translation cam．The follower slides up and down as the cam translates motion in the horizontal direction．Note that a pivoted follower can be used as well as a sliding-type follower．This type of action is used in certain production machines in which the pattern of the product is used as the cam．A variation on this design would be a three-dimensional cam that rotates as well as translates．For example，a hand-constructed rifle stock is placed in a special lathe．This stock is the pattern，and it performs the function of a cam．As it rotates and translates，the follower controls a tool bit that machines the production stock from a block of wood．Figure 6.4Positive-Motion Cams．In the foregoing cam designs，the contact between the cam and the follower is ensured by the action of the spring forces during the return stroke．However，in high-speed cams，the spring force required to maintain contact may become excessive when added to the dynamic forces generated as a result of accelerations．This situation can result in unacceptably large stress at the contact surface，which in turn can result in premature wear．Positive-motion cams require no spring because the follower is forced to contact the cam in two directions．There are four basic types of positive-motion cams: the cylindrical cam，the grooved-plate cam ( also called a face cam ) ，the matched-plate cam，and the scotch yoke cam．Cylindrical Cam．The cylindrical cam shown in Figure 6.5 produces reciprocating follower motion，whereas the one shown in Figure 6.6 illustrates the application of a pivoted follower．The cam groove can be designed such that several camshaft revolutions are required to produce one complete follower cycle．Grooved-plate Cam．In Figure 6.8 we see a matched-plate cam with a pivoted follower，although the design also can be used with a translation follower．Cams E and F rotate together about the camshaft B．Cam E is always in contact with roller C，while cam F maintains contact with roller D．Rollers C and D are mounted on a bell-crank lever，which is the follower oscillating about point A．Cam E is designed to provide the desired motion of roller C，while cam F provides the desired motion of roller D．Scotch Yoke Cam．This type of cam，which is depicted in Figure 6.9，consists of a circular cam mounted eccentrically on its camshaft．The stroke of the follower equals two times the eccentricity e of the cam．This cam produces simple harmonic motion with no dwell times．Refer to Section 6.8 for further discussion．CAM TERMINOLOGYBefore we become involved with the design of cams，it is desirable to know the various terms used to identify important cam design parameters．Thefollowing terms refer to Figure 6.11．The descriptions will be more understandable if you visualize the cam as stationary and the follower as moving around the cam．Trace Point．The end point of a knife-edge follower or the center of the roller of a roller-type follower．Cam Contour．The actual shape of the cam．Base Circle．The smallest circle that can be drawn tangent to the cam contour．Its center is also the center of the camshaft．The smallest radial size of the cam stars at the base circle．Pitch Curve．The path of the trace point，assuming the cam is stationary and the follower rotates about the cam．Prime Circle．The smallest circle that can be drawn tangent to the pitch curve．Its center is also the center of the camshaft．Pressure Angle．The angle between the direction of motion of the follower and the normal to the pitch curve at the point where the center of the roller lies．Cam Profile．Same as cam contour．BDC．Bottom Dead Center，the position of the follower at its closest point to the cam hub．Stroke．The displacement of the follower in its travel between BDC and TDC．Rise．The displacement of the follower as it travels from BDC to TDC．Return．The displacement of the follower as it travels from TDC or BDC．Ewell．The action of the follower when it remains at a constant distance from the cam hub while the cam turns．A clearer understanding of the significance of the pressure angle canbe gained by referring to Figure 6.12．Here FTis the total force acting on the roller．It must be normal to the surfaces at the contact point．Its direction is obviously not parallel to the direction of motion of the follower．Instead，it is indicated by the angle α，the pressure angle，measured from the line representing the direction of motion of thefollower．Therefore，the force FT has a horizontal component FHand a verticalcomponent FV．The vertical component is the one that drives the followerupward and，therefore，neglecting guide friction，equals the follower Fload．The horizontal component has no useful purpose but it is unavoidable．In fact，it attempts to bend the follower about its guide．This can damage the follower or cause it to bind inside its guide．Obviously，we want the pressure angleto be as possible to minimize the side thrust F．A practical rule of thumbHis to design the cam contour so that the pressure angle does not exceed 30o．The pressure angle，in general，depends on the following four parameters: ——Size of base circle——Amount of offset of follower——Size of roller——Flatness of cam contour ( which depends on follower stroke and type of follower motion used )Some of the preceding parameters cannot be changed without altering the cam requirements，such as space limitations．After we have learned how to design a cam，we will discuss the various methods available to reduce the pressure angle．故障的分析、尺寸的决定以及凸轮的分析和应用前言介绍：作为一名设计工程师有必要知道零件如何发生和为什么会发生故障，以便通过进行最低限度的维修以保证机器的可靠性。

机械工程专业毕业设计外文翻译

英文原文名Lthes 中文译名车床中文译文：车床车床主要是为了进行车外圆、车端面和镗孔等项工作而设计的机床。

车削很少在其他种类的机床上进行,而且任何一种其他机床都不能像车床那样方便地进行车削加工。

由于车床还可以用来钻孔和铰孔，车床的多功能性可以使工件在一次安装中完成几种加工。

因此，在生产中使用的各种车床比任何其他种类的机床都多.车床的基本部件有:床身、主轴箱组件、尾座组件、溜板组件、丝杠和光杠。

床身是车床的基础件。

它能常是由经过充分正火或时效处理的灰铸铁或者球墨铁制成。

它是一个坚固的刚性框架，所有其他基本部件都安装在床身上。

通常在床身上有内外两组平行的导轨。

有些制造厂对全部四条导轨都采用导轨尖朝上的三角形导轨（即山形导轨），而有的制造厂则在一组中或者两组中都采用一个三角形导轨和一个矩形导轨.导轨要经过精密加工以保证其直线度精度.为了抵抗磨损和擦伤，大多数现代机床的导轨是经过表面淬硬的,但是在操作时还应该小心，以避免损伤导轨。

导轨上的任何误差，常常意味着整个机床的精度遭到破坏.主轴箱安装在内侧导轨的固定位置上，一般在床身的左端。

它提供动力，并可使工件在各种速度下回转.它基本上由一个安装在精密轴承中的空心主轴和一系列变速齿轮(类似于卡车变速箱)所组成。

通过变速齿轮，主轴可以在许多种转速下旋转。

大多数车床有8～12种转速，一般按等比级数排列。

而且在现代机床上只需扳动2~4个手柄，就能得到全部转速。

一种正在不断增长的趋势是通过电气的或者机械的装置进行无级变速。

由于机床的精度在很大程度上取决于主轴，因此，主轴的结构尺寸较大，通常安装在预紧后的重型圆锥滚子轴承或球轴承中。

主轴中有一个贯穿全长的通孔,长棒料可以通过该孔送料.主轴孔的大小是车床的一个重要尺寸，因此当工件必须通过主轴孔供料时,它确定了能够加工的棒料毛坯的最大尺寸。

数字控制的机器比人工操纵的机器精度更高、生产出零件的一致性更好、生产速度更快、而且长期的工艺装备成本更低。

机械制造专业毕业设计英文翻译(doc 22页)

机械制造专业毕业设计英文翻译(doc 22页)英文翻译Chapter 4 portable rotating machinery vibration monitoring system design With the modernization of enterprise device management, how to make equipment, continuous, reliable, safe and efficient operation to meet the requirements of modern enterprise management, is particularly important. The rotating mechanical equipment during operation of the vibration signals generated a lot of hidden information that can help people to correctly judge the various types of rotating machinery during operation of the state. Theory of vibration analysis and condition monitoring technology is inseparable organisms. Based on vibration analysis of rotating machinery condition monitoring system is to run the process of rotating machinery vibration information generated by the core to determine rotating machinery is running or the anomaly occurred.4.1 The system worksThe system works: The acquisition rotating machinery vibration sensor equipment running in the process of the vibration signals, after filtering hardware circuit amplification, A / D conversion, and then upload the data through the USB interface to a computer for processing; host computer can be the data collector sample rate, channel selection and so the corresponding parameter settings; through the application of the software for signal analysis and processing and analysis of paint-related waveforms; and then, through therelevant waveform analysis and spectrum analysis to determine the health status of machinery and equipment.4.2 System Structure DiagramDesign concept of this system is the top-down design, the first device to achieve the overall planning function, and then divide the total work function to the hardware and software sub-modules to realize the system overall design block diagram shown in Figure 1.4.3 Vibration speed sensor selectionVibration sensor (Sensor) is a collection can be generated by rotating machinery vibration signals, according to a certain law of vibration signals are converted to their corresponding physical quantity or signal and another output device, is to achieve large-scale rotating machinery condition monitoring of an important link If there is no vibration sensor to the original vibration signals accurately capture and conversion, rotating machinery condition monitoring can not be achieved.By collecting vibration signal of a different nature can be classified as follows: acceleration, velocity, displacement and so on. Vibration sensor selection must take into account sensor performance requirements; sensor static and dynamic characteristics. Vibration sensor static characteristics of the main parameters are: linearity, resolution and sensitivity. The dynamic characteristics of vibration sensors used it to respond to certain criteria to represent the input signal. As the rotating machinery vibration signals output sinusoidal signal, so the dynamic characteristics of sensors used to indicate the frequency response. Rotating machinery vibration test commonly used types of sensors are piezoelectric sensors and inertial rate sensors.Piezoelectric sensors used for non-rotating components of the acceleration measurement. It is characterized by the use of a wide frequency range, usually 0.2 ~ 10k Hz, therefore, it is suitable for high-speed rotating machinery vibration tests. The quality of piezoelectric acceleration sensor is small, easy to install in mechanical equipment. However, piezoelectric sensors are high impedance, weak signal sensor, measuring the site vulnerable to electromagnetic, acoustic and thermal air currents and other interference, so that the output signal contains the part of non-vibration acceleration measurement points from a false signal.Inertial speed sensor is a contact-type vibration sensor, it is absolutely vibration velocity of the detected objects into moving parts moving relative to the absolute speed of the shell, and then through an internal transformation to the relative vibration velocity transform parts of the electromotive force, namely, by measuring the electromotive force to calculate the speed of rotating machinery vibration. Inertial speed sensor that has high sensitivity and low output impedance, but also the output power of a strong signal, so it is not susceptible to electromagnetic interference afternoon, for more complex and requires a long lead on-site, still higher signal to noise ratio. The sensor's frequency range between 0.008 ~ 1KHz, no special pre-amplifier, install easy to use.The system uses the VS Series Vibration velocity sensor shown in Figure 4-2, which measured bearing, chassis or structure of the vibration intensity and vibration intensity. Such sensors measure the vibration is relative to the absolute vibration of free space; its output voltage is proportional to the speed and vibration, so called velocity type vibration sensors. Can also convert the speed of traffic through the displacement of points re-display processing? This measurement can rotation or reciprocating body to conduct a comprehensive evaluation of working conditions, which directly installed on the machine outside, so maintenance is very convenient to use.How It Works: VS Series Vibration Monitoring speed sensor is the use of magnetic induction principle to vibration signals converted into electrical signals. It is mainly from the magnetic circuit system, inertial mass, spring damping components. The sensor rigid shell secured to a magnet, inertial mass (coil component), with spring suspension components on the housing. Work, the sensor installed on the machine, the machine vibration when the working frequency range of the sensor, the coil and magnet relative movement, cutting magnetic field lines, on-line circle produces induced voltage, the voltage is proportional to the value of vibration velocity. Then match with the secondary instrument, which shows that the amount of vibration velocity or displacement size.①sensitivity values are 80Hz, the speed of 18mm / s case determination of②Amplitude linearity: "3%; transverse sensitivity ratio:" 5%③Direction: (provides for horizontal direction 0 °)Vertical: 90 ° ± 10 °Horizontal: 0 ° ± 10 °④Output Resistance: ≤ 450; Insulation resistance :> 20M4.4 Hardware Design Module4.4.1 Analog signal conditioning circuitJP1 then collected the raw vibration sensors capture signal amplificationthrough the filter into the analog circuit A / D chip for A / D conversion, in order to host computer for data processing.1. Signal filteringVibration sensor will be a non-power rotating machinery vibration signals into electrical signals, but the vibration signals superimposed on the scene useless noise, these noise and vibration signals generated at the same time, some are mixed with the process of vibration signal transmission, the noise sometimes will be greater than the useful signal, thereby inundating useful signal. If you do not eliminate them, will be right behind the signal processing analysis to bring the error, and even sometimes lead to wrong conclusions, so the collected signal is filtered.Generally divided into low-pass filters, high pass, band pass and band stop filter, its frequency response characteristics as shown in Figure 4-2.Low-pass filter is the low-frequency signals while the high-frequency signals are not passed through the filter. High-pass filter and low-pass filter performance is just the opposite, namely, high-frequency signals through the low-frequency signal is not passed; band-pass filter is the frequency in a range ofthe signal through, while outside the scope of this Could not get it; band-stop performance and band-pass filter is the opposite, that is, within the scope of a certain frequency band signal is blocked, in which the signal outside the pass band. .Field Dynamic collected vibration signals are often mixed with a lot of useless noise, for noise, its frequency is difficult to quantify given the size of the value of design as long as the filter when considering high-frequency interference signal suppression. According to Nyquist's Law, data collection devices for data acquisition frequency must be greater than twice the highest frequency vibration signal, the signal can not occur until the frequency aliasing phenomenon, the need to design a low-pass filter for vibration signal through, filter out some high-frequency interference . The simplest low-pass filter formed by capacitors and resistors, shown in Figure, A simple RC low-pass circuit, the general call it passive low-pass filter.The low-pass filterFigure 4-3 shows the RC low-pass filter circuit, the voltage loop equation:Its gainThe availability of the actual gain ofGain value is a function of frequency in the low frequency area ω Minimal ，1,()1V R C A ωω= Signal pass; high frequency area ω Great ，1,()0V R C A ωω= Signal unreasonable 。

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缸体机械加工工艺设计发动机缸体是发动机零件中结构较为复杂的箱体零件，其精度要求高，加工工艺复杂，并且加工加工质量的好坏直接影响发动机整个机构的性能，因此，它成为各个发动机生产厂家所关注的重点零件之一。 1. 发动机缸体的工艺特点缸体为一整体铸造结构，其上部有4个缸套安装孔；缸体的水平隔板将缸体分成上下两部分；缸体的前端面从到后排列有三个同轴线的凸轮轴安装孔和惰轮轴孔。缸体的工艺特点是：结构、形状复杂；加工的平面和孔比较多；壁厚不均，刚度低；加工精度要求高，属于典型的箱体类加工零件。缸体的主要加工表面有顶面、主轴承侧面、缸孔、主轴承孔及凸轮轴孔等，它们的加工精度将直接影响发动机的装配精度和工作性能，主要依靠设备进度、工夹具的可靠性和加工工艺的合理性来保证。 2. 发动机缸体工艺方案设计原则和依据设计工艺方案应在保证产品质量的同时，充分考虑生产周期、成本和环境保护；根据本企业能力，积极采用国内外先进的工艺技术和装备，不断提高企业工艺水平。发动机缸体机械加工工艺设计应遵循以下基本原则：（1）加工设备选型原则加工设备选型采用刚柔结合的原则，加工设备以卧式加工中心为主，少量采用立式加工中心，关键工序—曲轴孔、缸孔、平衡轴孔加工采用高精度高速卧式加工中心，非关键工序—上下前后四个平面的粗铣采用高效并有一定调整范围的专用机床加工；（2）集中工序原则关键工序—曲轴孔、缸孔、平衡轴孔的精加工缸盖结合面的精铣，采用在集中在一道工序一次装夹完成全部加工内容方案，以确保产品精度满足缸体关键品质的工艺性能和有关技术要求。根据汽车发动机缸体的工艺特点和生产任务要求，发动机缸体机械加工自动生产线由卧式加工中心CWK500和CWK500D加工中心、专用铣/镗床、立式加工中心matec-30L等设备组成。（1）顶底面及瓦盖止口面粗铣组合机床本机床为双面卧式专用铣床，采用移动工作台带动工件，机床采用进口西门子S7-200PLC系统控制，机床设独立电控柜，切削过程自动化完成，有自动和调整两种状态；（2）高速卧式加工中心CWK500 该加工中心可实现最大流量的湿加工，但由于设备自动排屑处理系统是通过位于托盘下的内置宽式排屑器而完成，该加工中心可以进行干加工；机床主轴转速6000r/min，快速进给速度38m/min；（3）前后端面粗铣组合机床机床采用液压传动；控制系统采用进口西门子S7-200PLC系统控制，机床具有一定的柔性；（4）采用机床TXK1500 本机床有立式加工中心改造而成形，具备立式加工中心的特点及性能，该机床具有高精度、高强度、高耐磨度、高稳定性、高配置等优点；（5）高速立式加工中心matec-30L 该加工中心主轴最高转速9000 r/min。控制系统采用西门子公司SINUMERIK840D控制系统（6）高速卧式加工中心CWK500D 主轴最高转速15000 r/min。 3. 发动机缸体机械加工工艺设计的主要内容发动机缸体结构复杂，精度要求高，尺寸较大，是薄壁零件，有若干精度要求较高的平面和孔。发动机缸体机械加工的工艺特点是：主要是平面和孔的加工，加工平面一般采用刨、铣削等方法加工，加工孔主要采用镗削，加工小孔多用钻削。由于缸体结构复杂，因此如何保证各表面的相互位置精度是加工中的一个重要问题。 3.1 毛坯的选择发动机缸体采用的材料一般是灰铸铁HT150、HT200、HT250，也有采用铸铝或者钢板的，此发动机缸体采用高强度合金铸铁。缸体在加工前进行时效处理，以消除铸件内应力和改善毛坯的力学性能。提高毛坯精度，减少加工余量，是提高自动生产线系统生产率及加工质量的重要措施。由于国外箱体类零件毛坯质量和精度较高，其生产线系统已实现了毛坯直接上线，既省去了毛坯检查装置，也节省了由于毛坯质量问题而浪费的加工工时，提高了综合效益。因此，精化毛坯是提高生产率最有潜力的出路。对于发动机缸体生产线，可在零件上线前粗铣六个面，去除大部分余量，便于零件直接上线。 3.2机械加工工艺基准的选择和加工选择合理的加工工艺基准，直接关系到能否保证零件的加工质量。一般来说，工艺基准可分为粗基准和精基准。（1）粗基准对于上线的毛坯，其粗基准的选择尤为重要，如果粗基准选择不合理，会使加工余量分布不均匀，加工面偏移，造成废品。在缸体生产线中，我们采用侧面作为粗基准；（2）粗基准对于发动机缸体这种箱体零件来说，一般采用“一面两销”为全线的统一基准。对于较长的自动自动生产线系统，由于定位销孔在使用过程中的磨损造成定位不准确，因此，将定位销孔分为2-3段使用。在缸体定位销孔的加工中，我们采用了以侧面、底面和主轴孔定位，在加工中心上加工。 3.3 机械加工加工阶段的划分和工序的安排一个零件往往有许多表面需要加工，当然表面的加工精度是不同的。加工精度较高的表面，往往要经过多次加工；而对于加工精度低的表面，只要经过一两次就行了。因此，拟定工艺顺序时，要抓住“加工精度高的表面”这个矛盾，合理安排工序和合理划分加工阶段。安排工艺顺序的原则是：先粗后精，先面后孔，先基准后其他。在发动机缸体的机械加工中同样应遵循这一原则。（1）粗加工阶段在发动机缸体的机械加工过程中，安排粗加工工序，对毛坯全面进行粗加工，切去大部分余量，以保证生产效率；（2）半精加工阶段在发动机缸体的机械加工过程中，为了保证一些重要表面的加工精度，安排一些半精加工工序，将精度和表面粗造度要求中等的一些表面加工完成，而对要求高的表面进行半精加工，为以后的精加工做准备；（3）精加工阶段对精度和表面粗造度要求高的表面进行加工；（4）次要小表面的加工如螺纹孔，可以在精加工主要表面后进行，一方面加工时对工件变形影响不大，同时废品率也降低；另外，如果主要表面出废品后，这些小表面就不必再加工了，从而避免浪费工时。但是，如果小表面的加工很容易碰伤主要表面时，就应该把小表面加工放在主要表面的精加工之前；（5）辅助工序也要妥善安排如检验工序，在零件粗加工阶段之后，关键工序加工前后，零件全部加工完毕后，都要适当安排。对加工阶段进行划分，具有以下好处：首先，可以在粗加工后采取措施消除工作内应力，保证精度；其次，精加工放在最后面，不至于在运输过程中损坏工件已加工表面；再次，先粗加工各面，可以及早发现毛坯缺陷并及时处理，不会浪费工时。不过对于一般小工件就不要分的很细。 3.4 缸体的主要加工表面和辅助工序缸体主要加工表面和辅助工序有：（1）平面加工目前，铣削是发动机缸体平面加工的主要手段，国内铣削进给量一般为300-400mm/min，与国外铣削进给量2000-4000 mm/min相比，相差甚远，有待于提高，因此，提高铣削进给量，缩短辅助时间，是提高生产效率的主要途径，发动机缸体精加工一些平面时的铣削进给量达到2399mm/min，大大提高了效率；顶面的铣削是缸体加工中的一个关键工序，其平面度要求为0.02/145mm，表面粗造度为Ra1.6um。在缸体的加工中，采用侧面和主轴轴承孔定位，顶面、底面和中间瓦盖面同时加工，在加工中采用线外对刀装置，能较好地满足发动机缸体加工精度要求；（2）一般孔系的加工一般孔系的加工仍采用传统的钻、扩、镗、铰、攻丝等工艺方法。课题在设计具体的工艺方案时，采用涂层刀具、内冷却刀具等先进刀具，采用大流量冷却系统，大大提高了切削速度，提高了生产率；（3）深油孔加工传统的加工方法是采用麻花钻进行分级进给，其生产效率低，加工质量差。在发动机缸体深油孔的加工中，采用枪钻工艺；（4）三轴孔的加工三轴孔的加工为缸体孔系加工中精度要求高，工时长的限制性工序。因此，工序安排、加工方法、刀具等都应该特别注意。合盖前加工，既缸体半圆孔和主轴承盖得加工，其主要目的是去除毛坯余量、释放应力，为后序加工做准备；在加工中心上加工曲轴孔时，采用双面镗孔，先在曲轴孔一段端镗孔到1/2长度时，然后工作台回转180度，从另外一端再镗另一1/2长；（5）缸孔的加工缸孔的加工时缸体机械加工中的关键工序之一，一般情况下，其加工工艺过程为粗镗、半精镗、精镗和珩磨。为及早发现缸孔内壁的铸造缺陷，消除应力，应尽量提前粗镗缸孔；由于缸孔的结构特点不同，需采用珩磨工艺，以提高缸孔表面质量。在大批量生产中，缸孔的珩磨一般采用多轴珩磨机或珩磨自动线。再次我们采用珩磨自动线，由粗珩、精珩和检测三台设备组成；（6）清洗清洗分为湿式清洗和干式清洗。缸体机械加工自动生产线采用大流量湿式清洗；（7）检测检测分为在线检测和线外检测两种。在发动机缸体的质量检测中，根据实际情况采用线外检测，主要采用三坐标测量机对缸体进行综合测量，每200件抽查1-5件，每班抽查一件。 4. 小结通过对发动机缸体的结构和工艺特点进行分析，论述了发动机缸体机械加工工艺方案的原则和依据以及切削用量的选择，并以高速铣削和调头镗孔为例，设计、分析了发动机缸体的高速铣削和调头镗孔工艺过程，及在加工中需要注意的问题。 Cylinder block machining process design Engine parts engine block is a more complex structure of spare parts box, its high precision, complex process, and the processing quality will affect the overall performance engine, so it has become the engine manufacturer's focus parts one. 1.Technical Characteristics of the engine cylinder block Cylinder cast for a whole structure, and its upper part 4 cylinder mounting hole; cylinder standard cylinder is divided into upper and lower divisions into two parts; cylinder to the rear of the front-side arrangement of the previous three coaxial mounting hole of the camshaft and the idler axle hole. Cylinder process features are: the structure of complex shape; processing plane, more than holes; uneven wall thickness and stiffness is low; processing of high precision typical of box-type processing part. The main processing of the surface of cylinder block top surface, the main bearing side, cylinder bore, the main and camshaft bearing bore holes and so on, they will directly affect the machining accuracy of the engine assembly precision and performance, mainly rely on precision equipment, industrial fixtures reliability and processing technology to ensure the reasonableness. 2.Engine block process design principles and the basis for Design Technology program should be to ensure product quality at the same time, give full consideration to the production cycle, cost and environmental protection; based on the enterprises ability to actively adopt advanced process technology and equipment, and constantly enhance their level of technology. Engine block machining process design should follow the following basic principles: (1) The selection of processing equipment ,the principle of selection adopted the principle of selection adopted the principle of combining rigid-flexible, processing each horizontal machining center is located mainly small operations with vertical machining center, the key process a crank hole, cylinder hole, balancer shaft hole High-speed processing of high-precision horizontal machining center, an upper and lower non-critical processes before and after the four-dimensional high-efficiency rough milling and have a certain adjustment range of special machine processing; (2) focus on a key process in principle process the body cylinder bore, crankshaft hole, Balance Shaft hole surface finishing and the combination of precision milling cylinder head, using a process focused on a setup program to complete all processing elements in order to ensure product accuracy The key quality processes to meet the cylinder capacity and the relevant technical requirements; According to the technological characteristics of automobile engine cylinder block and the production mandate, the engine block machining automatic production line is composed of horizontal machining center CWK500 and CWK500D machining centers, special milling/boring machine, vertical machining centers matec-30L and other appliances. (1) top and bottom, and tile covered only the combination of aperture rough milling machine dedicated to this machine to double-sided horizontal milling machine, using moving table driven parts, machine tools imported Siemens S7-200PLC system