1、Unit 7 CAD/CAM/CAPP,CAD/CAM is a term which means computer-aided design and computer-aided manufacturing. It is the technology concerned with the use of digital computers to perform certain functions in design and production. This technology is moving in the direction of greater integration of desig
2、n and manufacturing, two activities which have traditionally been treated as distinct and separate functions in a production firm. Ultimately, CAD/CAM will provide the technology base for the computer-integrated factory of the future. Computer-aided design (CAD) can be defined as the use of computer
3、 systems to assist in the creation, modification, analysis, or optimization of a design. The computer systems consist of the hardware and software to perform the,截然不同的,最终，最后,协助,形成,优化,设计方案,specialized design functions required by the particular user firm. The CAD hardware typically includes the compu
4、ter, one or more graphics display terminals, keyboards, and other peripheral equipment. The CAD software consists of the computer programs to implement computer graphics on the system plus application programs to facilitate the engineering functions of the user company. Examples of these application
5、 programs include stress-strain analysis of components, dynamic response of mechanisms, heat-transfer calculations, and numerical control part programming. The collection of application programs will vary form one user firm to the next because their product lines, manufacturing processes, and custom
6、er markets are different. These factors give rise to differences in CAD system requirements.Computer-aided manufacturing (CAM) can be defined as the utilization of,终端,应力,动力学特性,机构,热传递,集，集合,产品系列,外围的,computer systems to plan, manage, and control the operations of a manufacturing plant through either di
7、rect or indirect computer interface with the plants production resources. As indicated by the definition, the applications of computer-aided manufacturing fall into two broad categories:(1) Computer monitoring and control. These are the direct applications in which the computer is connected directly
8、 to the manufacturing process for the purpose of monitoring or controlling the process.(2) Manufacturing support applications. These are the indirect applications in which the computer is used in support of the production operations in the plant, but there is no direct interface between the computer
9、 and the manufacturing process. Increasing Drafting Productivity,CAD/CAM systems can entail a whole new set of drafting philosophies, all of which enhance productivity. For instance, most systems now on the market have a number of built-in functions that make new and useful drafting techniques autom
10、atically. Layering, for example, enables drafters to create drawings in logical segments that can be stored separately for easy identification; but the segments can still be output together, in one single piece, which illustrates the entire drawing at once. The method is analogous to the anatomical
11、drawings we are used to seeing in biology texts. The skeleton, nerves, internal organs, blood vessels, and muscles are all represented on individual overlays of clear plastic. They can be viewed individually, or, by laying them on top of one another, all together, to show how the pieces fit in relat
12、ion to one another. Layering with a graphics system uses the same principle except the overlays are logical rather than physical. The uses for this are myriad. Layers can be used to separate,（使）成为必要，需要,固有的,分层,相似的，类似的,解剖（学）的,骨骼,神经,血管，脉管,肌肉,覆盖物,无数的,English and metric dimensioning information, inventor
13、y data, textual information, electrical requirements, plumbing, machine tool paths, and a host of other thing. The result is cleaner, less cluttered drawings.Another example of productivity enhancement for drafting might involve automating auxiliary views of a design. By pressing the right button or
14、 by entering the right command, a drawing could be turned 90 degrees in one direction or another. Three-dimensional designs could be rotated on any axis or displayed in any of several projections.The potential is really endless. Productivity increases are limited only when system management philosop
15、hies are limited. As an additional example, consider a drafting center for an architectural firm that specializes in designing warehouses. Much of the design work is repetitive and can be carried over from,英制的,公制的,（零件）清单,管路,杂乱的,辅助视图,投影,理念,仓库,重复的,one job to the next. In such a situation, standard com
16、ponents of each drawing can be automated by creating macros. These macros are nothing more than a series of graphics system commands strung together and executed as a single unit to build, for example, a standard floor plan or a standard staircase, or a standard door and door frame. The system can d
17、o the work in seconds and the drafter is relieved from recreating that part of the design each time it must be inserted into a drawing.Other macro programs could be useful. A set of commands might be put together that change the dimensioning of a drawing automatically from English to metric units or
18、 that automatically scale an entire drawing and rotate it to a desired orientation or that generate a bill of materials list for complicated engineering drawing.,宏指令,串在一起,楼梯,清单,To take it one step further, remember that entire designs can be stored on the system. When the drafter receives a job that
19、 has specifications similar to a stored drawing, he merely retrieves it, brings it into working storage, and edits those portions of the design that are not consistent with the specifications of the new job. Productivity increases are thus compounded. The original job is speeded up, and that job, in
20、 turn, is used to speed up the next job even further. This illustrates the need to maintain a complete and up-to-date data base that can be accessed easily by all users.,指标，规格,只是,复合化,包含最新信息的,数据库,存取,生产力,举例说明,Exercises,Translate the following words into English,优化,机构,辅助视图,仓库,应力,投影,宏指令,数据库,optimization
21、,mechanism,auxiliary view,warehouse,stress-strain,projection,macro,data base,Translate the following words into Chinese,distinct,ultimately,entail,built-in,analogous,anatomical,myriad,截然不同的,最终，终于,（使）成为必需，需要,固有的,相似的，类似的,无数的,解剖（学）的,cluttered,杂乱的,Part B Grammar and Translation,增译英汉两种语言，由于表达方式不尽相同，翻译时常常
22、需要填词。,The operator can use the cutter radius compensation offset to help with sizing.,操作员也可以使用刀具半径补偿偏置功能帮助加工到要求的尺寸。,1. 抽象名词后加名次使其具体化翻译某些由动词或形容词派生来的抽象名词时，可根据上下文在其后增添适当的名词，使其更符合汉语习惯。,2. 增加表达时态的词,The CNC operator will not know for certain whether the tool length compensation value is perfectly correct
23、until the first workpiece is machined.,数控操作员在第一个工件加工好之前，不能确定刀具长度补偿值是否完全正确。,3. 增加反映背景情况的词、解说性的词增加反映背景情况的词、解说性的词可以使汉语语意明确，根据上下文增词，符合业内人士的表达习惯。,As PC-based CAD/CAM software grows more sophisticated, it becomes difficult for a shop to decide exactly what they require.,基于PC的CAD/CAM软件变得越来越复杂，车间领导很难决定他们真正需
24、要什么样的软件。,Consequently, production costs can be high and lead times ( ) excessive.,结果，生产成本可能会很高，交货期可能会很长。,4. 增添原句中省略的成分如：英语倒装句中为了避免句子部分内容重复而省略的部分，译成汉语时应把它表达出来。,Because a problem with the program could damage costly machinery and cutting tools, computer simulations may be used to check the program instead of a trial run.,因为程序有问题会对机床和刀具造成极大的损坏，因此可用计算机仿真的方法检查程序的正确性，而不是用试运行的方法。,can be,
