英文翻译(数控).doc

沈阳航空工业学院毕业设计（外文翻译）Production Systems DesignThe design of a production system starts with the design of the product to be manufactured. Figure 6. 1 describes a typical sequence of steps starting with a product design concept that culminates in a final product design for manufacture. Product engineers are those individuals in a manufacturing organization most familiar with the function of a product.and the customers changing needs relative to that product.Figure 6. 1 The design manufacturing Interface.Arts-Way Manufacturing is a manufacturer of farm machinery in Armstrong, Iowa. As soon as the beet harvesting season comes to an end at the end of summer, Arts Way product engineering and marketing personnel evaluate their most recent harvester design successes and any unique conditions or problems that affected the performance of their equipment. Theres nothing like a harvest to bring to light the strengths and weaknesses of a harvester design. As soon as the harvester performance information is collected and evaluated and customer and dealer Inputs have been reviewed. it is likely that design improvements and related engineering tests will begin immediately for an improved harvester product to be available for next summer. The more mature is the design. the fewer design changes that will likely be developed during the next improvement cycle. This is the kind of interest a small manufacturer has in its products that no amount of central planning in the Soviet economy could have ever successfully duplicated, The Russians should talk to the people in Armstrong, Iuwa, and watch them analyze, design. And make harvesters if they want to learn how to make farm machinery the American way. If all goes well, the nine months between harvests will provide sufficient time to make the desired engineering tests,and to add design improvements needed before the release of material requisitions, so that next years improved harvesters will he ready in time, It is not uncommon that, as the time approaches to make material releases for the improved designs, product engineering will beg for more time to run one more test. A saying in the.Architectural and Engineering (A&E) business often applies in this situation: Sooner or later you have to shoot the engineer and build the building. The best compromise often is for some product improvements to wait for next years product design. It will be noted in reviewing Figure 6. 1 that much of the shove effort lies in interactions between product engineering, manufacturing engineering, and production. The manufacture of a new design is always a process of discovery. In Frederick W. Taylors days, the new design for a machine element might be a line drawn on the molding shop floor, which the master mold maker would then use to produce a stronger machine element for the next test of.the machine. When the stronger part was molded. It would be Installed on the machine, the machine would run for some seconds, minuites, or hours. And would fail again, often in a different place, and the process would be repeated. Ultimately, a machine design would evolve that would produce a machine that would run all the time. These machines were sold to customers. With todays perfected engineering knowledge it is much more likely that the design will perform as designed, if not the first time. with far fewer prototype redesigns. Expert systems and Taguchi methods, both to be discussed later in this text. Provide the means for doing a much better job today of optimizing both the product design in its underlying function and identifying the best means of manufacture for producing a highquality. Reliable, and cost effective product.Computer-Aided Drafting and design (CADD)Whereas design may have been accomplished with a stick on the molding shop floor in Tailors time, CAD/CAE/CAM (computer-aided design, computer-aided engineering ,computer-aided manufacturing) is becoming the preferred means today for producing designs. Most people think of CADD (computer-aided drafting and design) as simply electronic drafting, which greatly understates the computer revolution associated with the tasks implied in Figure 6. 1. The following excerpt from a paper by Floyd concerning the use of CADD in the automotive industry provides some insight as to the overall comprehensiveness of the computer revolution in engineered product design today.CAD/CAE/CAM for the Automotive IndustryBryan FloydExecutive ManagerMechanical Design/Engigneering/Manunfacturing. Intergraph CorpFully integrated design, engineering, and manufacturing. Automotive manufacturing is a complex business that integrates the efforts of many departments and disciplines. Tools that promote the integration of design, engineering, and manufacturing processes yield the greatest productivity benefits. Intergraph offers automakers the master model Concept asingle Intelligent product definition that drives all aspects of development, from concept through production. Intergraphs tightly integrated systems eliminate intermediate transfer or re-entry of data between design. Analysis, and manufacturing phases. Additionally, all product development capabilities are simultaneously accessible through a single user interface, allowing engineers to combine functions, as needed, without changing environments, Conceptual design and styling. Intergraph systems provide advanced tools for conceptual design and automotive styling, with high-performance graphics for concept visualization and communication. I/DESIGN. Intergraphs Industrial design system. Includes high precision modeling and photo realistic rendering capabilities that aid in developing a functional, ergonomic, and aesthetic design. Precision geometric modeling. Automotive engineers require CAD/CAE/CAM modeling that ran precisely describe complex surfaces and completely model Intricate assemblies. Intergraph meets these demands with the Engineering Modeling System (I/EMS). which isbased on highly accurate non-uniform rational B-spline (NURBS) mathematics. Intergraph is distinguished from other CAD/CAE/CAM vendors by offering advanced geometric modeling as a foundation for analysis and manufacturing.Solid modeling. When designing an automobile, engineers must know Critical geometric properties including masses and displacement volumes that are only available with solid modeling techniques. Property calculations, such as volume, cross sectional area. radius of gyration, moments of Inertia. mass density, and others are included in I/EMS as standard functions supporting the sofwares solid modeling capability.Assembly design and configuration management. Automotive development depends on a wealth of application data for thousands of components. Intergraph provides Product Data Manager (I/PDM) as a complete system for controlling and managing access to the product database. Without regard for physical storage locations, file names. or operating system platforms. engineers can locate and retrieve data from any location on a heterogeneous network. Structural analysis. By simulating performance characteristics of designs before products are built, automakers complete designs in less time and reduce overdesign. Finite element analysis techniques help ensure compliance with performance standards and reduce the risk of failure in the field. These benefits are achieved with automatic and interactive meshing.Hadaptive refinement technology and integrated solver，and full postprocessing functions,all available with lntergraphs Finite Element Modeling (I/FEM system.Plastics design and analysis. When Integrated Into the mechanical design process, plastics design and analysis functions can improve the quality of plastic components, increase yield, and reduce manufacturing cycle times. Plastics engineers can predict plastics behavior under molding conditions using the injection Flow Analysis (I/FLO) package. The FLOW model can then be used in conjunction with the Plastics Cooling Analysis (l/COOL) software to analyze heat transfer in cooling circuit layouts. By analyzing temperature distribution .Engineers can reduce distortion and cooling times for infected plastic parts.Mechanism and kinematic analysis. Engineers designing mechanical systems must determine how forces and motions vary over time to achieve performance goals and eliminate part to part Interference. With Mechanical Systems Modeler (I/MSM). engineers analyze motions and part to part interactions and conduct kinematic and kinetostatic analyses with the built in solution program. To conduct static equilibrium and dynamic analyses, engineers have access to I/MSMs modeling and post processing functions and direct Interface to third party programs, including ADAMS and DADS.Manufacturing capabilities. The diversity of processes required in automotive production demands a versatile set of manufacturing tools. Intergraph manufacturing solutions include the Industrys broadest range of NC programming and fabrication tools, I/NC. Intergraph s off line programming environment. Supports machining capabilities for multiple-axis milling, thermal cutting, wire EDM, turret punching, and turning. Integrated fabrication software addresses flat pattern development and nesting processes.Integrated designand manufacturing. To minimize production lead times, Increase equipment and material yields, and reduce errors. Intergraph offers automakers complete CAD-to-CAM integration. M8nufacturing processes are developed directly from the design model, An intelligent database structure automatically maintains the relationships between component geometries, toolpaths, machine and tool characteristics, and other variables to greatly reduce the input required to generate, maintain, and verify manufacturing data.Electronic design and analysis. The Increasing electronic content of automobiles demands coordination of electronic and mechanical design processes. To satisfy this demand Intergraph provides a full suite of Integrated electronics design applications. The Design Engineer series of products works in conjunction with mechanical design applications topromote a concurrent engineering environmentFacilities mauagement. To operate at peak efficiency. manufacturing facilities must optimize spatial and functional relationships. Designers can avoid trial-and-error space planning and factory layout with Project Planner, a software package that models facilities, simulates manufacturing scenarios, and determines an optimal lit within the building envelope.Computer Aided Process Planning.According to the Tool & Manufacturing Engineers Handbook, process planning is the systematic determination of the methods by which a product is to be manufactured economically and documentation. Processes, machines, tools, operations, and sequences must be selected. Such factors as feeds, speeds, tolerances, dimensions, and costs must be calculated. Finally, documents in the form of setup instructions, work instructions, illustrated process sheets, and routings must be prepared. Process planning is an intermediate stage between designing and manufacturing the product. But how well does it bridge design and manufacturing?Most manufacturing engineers would agree that, if ten different planners were asked to develop a process plan for the same part, they would probably come up with ten different plans. Obviously, and, in fact, there is no guarantee that any one of them will constitute the optimum method for manufacturing the part.What may be even more disturbing is that a process plan developed for a part during a current manufacturing program may be quote different form the plan developed for the same or similar part during a previous manufacturing program and it may never be used again for the same or similar part. That represents a lot of wasted effort and produces a great many inconsistencies in routing, tooling, labor requirements, costing, and possibly even purchase requirements. Of course, process plans should not necessarily remain static. As lot sizes change and new technology, equipment, and processes become available, the most effective way to manufacture a particular part also changes, and those changes should be reflected in current process plans released to the shop.A planner must manage and retrieve a great deal of data and many documents, including established standards, mach-inability data, machine specifications, tooling inventories, stock availability, and existing process plans. This is primarily an information-handling job, and the computer is an ideal companion.There is anther advantage to using computers to help with process planning. Because the task involves many interrelated activities, determining the optimum plan requires many-iterations. Since computer can readily perform vast numbers of comparisons, many more alternative plans can readily perform vast numbers of comparisons, many more alternative plans can be explored than would be possible manually.A third advantage in the use of computer-aided process planning is uniformity.Several specific benefits can be expected from the adoption of computer-aided process-planning techniques:l Reduced clerical effort in preparation of instructions.l Fewer calculation errors due to human error.l Fewer oversights in logic or instructions because of the prompting capability available with interactive computer programs.l Immediate access to up-to-data information from a central database.l Consistent information, because every planner accesses the same database.l Faster response to changes requested by engineering of other operating departments.l Automatic use of the latest revision of a part drawing.l More-detailed, more-uniform process-plan statements produced by word-processing techniques.l More-effective use of inventories of tools, gages and fixtures and a concomitant reduction in the variety of those items.l Better communication with shop personnel because plans can be more specifically tailored to a particular task and presented in unambiguous, proven language.l Better information for production planning, including cutter-life, forecasting, materials-requirements planning, scheduling, and inventory control.制造系统设计制造系统设计开始于产品制造的设计，图6.1介绍的是一项产品从概念设计到最后完成产品的典型的次序步骤。产品工程师是那些在产品制造业中最熟悉产品功能和客户的不同需求的人。 图6.1 Art-Way农机制造业厂商在啊姆斯特朗、爱荷华地区。在收获季节即将结束时，Art-Way 的设计人员就会衡量收割机设计的成功之处，械的工作条件，以及特殊情况影响了机械运行的问题，没有什么可以象收割一样来揭示收割机的优点和不足了。尽快的收集收割机的工作资料信息和做出的评估以及经销商和客户资金的投入。这样，设计的改善和相关的动力改进将会马上为了明年的更新进的收割机进行测试和生产。比较成熟的设计将会在以后的设计周期减少改进。这种小型厂商的利益,没有自己产品的金额,在中央规划 苏联经济能不断成功复制。俄国人效仿啊姆斯特朗、爱荷华人，看他门农机的设计和分析去制造走自己的美国之路。如果一切顺利，在丰收季节之间将有足够的9个月时间去做工程调整，补充，设计改进，以及物资调用。这样明年的新收割机就会准备好。工程上乞求多做实验是很平常的。在建筑和工程上有句话：“Sooner or later you have to shoot the engineer and build the building。”最好的折衷往往是一些产品的改进等待明年的产品设计回顾图6.1上述办法在产品工程、制造业工程学和生产之间的相互作用这种方式有着很大的帮助。一个新的制造设计总是体现一个发现的过程。在Frederick W.Taylor 当天零件制造商会画出模具图，用更好的机械做出模具从而生产零件。当生产出来的更好的零件被安装在机械中，这个部件会一直不停的运转 ，不停的重复一个运动过程来测试它的强度。最终一个一直使用的老部件将被它取代，机械的设计也将演变。这些被通过完善的设计理念和设计方法制造出的机器被卖给了客户，如果不是第一次设计则以前的设计将被用作借鉴原型。专家系统和Taguchi方法将在本文后面解释，可靠性高，优质的产品是在优秀的产品设计和最佳的制造手段的前提下制造的。计算机辅助草图设计在Taylor时间内，设计就是基础。计算机辅助设计/计算机辅助制造/计算机辅助工艺设计今天正在成为首选方式制作设计. 大多数人认为,作为单纯的电子起草设计是最好的设计方式。然而人们大大低估了计算机革命对人类的隐含意义。图6.1 以下节录了一份有关使用弗洛伊德在汽车工业提供一些具体例子。今天电脑革命已经被设计人士用做全面性整体策划产品设计。自动化工业中的CAD/CAE/CAM布莱恩弗洛伊德行政经理机械设计/工程/制造Intergraph总公司自动话制造是许多部门促进设计、工程、制造的整合，一系列的生产线推进一体化设计、工艺、产量提高，是促进设计的综合化的工具而且给制造的过程产生很多的好处。Intergraph提供汽车制造者主要式样概念：独特，聪明的产品限定使得所有方面有了很大的发展，从概念到生产，Intergraph的紧紧集成了系统的数据再进入设计、分析和制造业阶段，另外，没有变化的环境，所有产品开发和联合设计都是通过一个单用户接口使得得到允许工程师在需要时可以共同使用。精确的几何学模式。制造工程师可以精确地描述复杂表面和完全地塑造零件模型。Intergraph适应这些需要基于高度准确不均匀的合理的多槽轴(NURBS)的工程数学产生的 (I/EMS)工程学。Intergraph通过卓越的先进零件塑造提供给给凸轮供营商作为产品的分析和制造。实体造型。在设计一辆汽车,工程师必须知道关键性能包括群众和位移量,自己只是提供实体建模技术.实体包括很多设计参数例如容量，断面面积、回旋半径，转动惯量，许多密度和其他在I/EMS包,括作为支持软件的实体造型的软件部分装配设计和配置管理。汽车的发展有赖于丰富的数以千计的零件,应用数据。Intergraph提供产品数据管理(I/PDM系统)作为一个,完整的管理体系,并YO拥有产品数据库.不同的储存地点的档案,或是操作系统平台,工程师可以找到并定位于任何一种形式通过联网取回数据.结构分析。设计建造之前模拟产品性能特点,用较少时间完成汽车设计,并减少了设 计量. 有限元分析技术,协助确保制造绩标准,减少失败的风险。这些有利条件可以实现自动和交互式啮合,细化和综合技术求解、全功能后处理