数控技术专业英语(第2版)：Unit 7 CAD and Applications

1、Unit 7,Dialogue Text A Supplementary Reading Translating Skills 7,Dialogue,Fu: Let me introduce the group. This is Mr. Jiang, dean of the Electromechanical Department, this is Mr. Robert, General Manager of Sino-German Auto Parts Manufacturing corporation, and this is Mr. Jin, Manager of the Personn

2、el Department. Jiang: How do you do? Robert: Fine, thanks,下一页,返回,Dialogue,Jiang: Welcome to our training center and CAD/CAM lab. This is our NC training center, where the students majoring in electromechanical integration and technological foreign languages accept practice and training, and an impor

3、tant teaching and scientific research base for teachers of Electromechanical Department. Robert: Mr. Jiang, can we have a look at the equipment? Jiang: Of course. This is a NC lathe with a MITSUBISHI M50 L NC system of Japanese. We can not only straight turn, thread, and cut slots, but also drilling

4、, boring and reaming holes on it,下一页,上一页,返回,Dialogue,Robert. Ok, quite good. Jiang: This way please. This is a NC milling machine with a FANUC system. We can mill planes, curve surfaces, drill holes, etc. in it. These are the products we accept to process and they are made by our graduates majoring

5、in NC technology. These are the products we accept to process and are made by our graduates majoring in NC processing,下一页,上一页,返回,Dialogue,Robert: It seems that your graduates are really good at and rich in practical experience. Our enterprise really needs such technicians who not only have a good co

6、mmand of theoretical knowledge but also are good at operations. Can you ask your students to operate the Machining Center? Jiang: Yes, lets watch how to make a part with multi-operation and complicated surfaces by CAD/CAM. Now, let our students show you how to do it. Robert: Excellent,下一页,上一页,返回,Dia

7、logue,Jiang: Here we are in our CAD/CAM Center. Our computers are all Pentium 586, with the memory of 64-128M and AutoCAD, MasterCAM, EDA and PLC software. There is also Pro-Engineer in the teachers computer, with multi-media such as big-screen projection. In this computer room, we mainly give class

8、es such as computer fundamentals and applications, CAD/CAM, Numerical Programming, EDA, PLC, Computer Networks, E-Commerce and so on. Now, we are doing CAD intermediate training,下一页,上一页,返回,Dialogue,Jin: Im very satisfied with your training and curriculum. Those you train are the compound technicians

9、 with integrated knowledge of industrial technology, business management and foreign languages. Our company is willing to accept your excellent graduates. Jiang: Thank you very much,下一页,上一页,返回,Dialogue,Robert: You deserve it. With the broadening of our business, we need to employ some new staff. Ple

10、ase contact Mr. Jin, manager of the personnel department to arrange for the interview. Fu: Thank you very much. Robert： Ok, we are running short of time. Im afraid I must say goodbye to you now. lets talk it over another day. Goodbye. Jiang: Goodbye! Welcome to our school again,上一页,返回,Text A,CAD and

11、 Applications Before we present the basics of CAD, it is appropriate to give a brief history. CAD is a product of the computer era. It originated from early computer graphic systems to the development of interactive computer graphics. Two such systems include the Sage Project2 at the Massachusetts I

12、nstitute of Technology (MIT)1 and Sketchpad. The Sage Project was aimed at developing CRT displays and operating Sketchpad was aimed at developing CRT displays and operating systems. Sketchpad was developed under the Sage Project,下一页,返回,Text A,A CRT displays and light pen input were used to interact

13、 with the system. This coincidentally happened at about the same time that NC and APT (Automatically Programmed Tool) first appeared3. Later, X-Y plotters were used as the standard hard-copy output device for computer graphics. An interesting note is that an X-Y plotter has the same basic structure

14、as a NC drilling machine except that a pen is substituted for the tool on NC spindle4,下一页,上一页,返回,Text A,In the beginning, CAD systems were no more than graphics editor with some built-in design symbols. The geometry available to the user was limited to lines, circular arcs, and the combination of th

15、e two. The development of free-form curves and surfaces, such as Coons patch, Beziers patch, and B-spline, enables a CAD system to be used for sophisticated curves and surface design. Three-dimensional CAD system allow a designer to move into the third dimension. Because a three-dimensional model co

16、ntains enough information for NC cutter-path programming, the linkage between CAD and NC can be developed,下一页,上一页,返回,Text A,So called turnkey CAD/CAM systems were developed based on this concept and became popular in the 1970s and 1980s. The 1970s marked the beginning of a new era in CAD -the invent

17、ion of three-dimensional solid modeling. In the past, three-dimensional, wire-frame models represented an object only by its bounding edges. They are ambiguous in the sense that several interpretations might be possible for a single model. There is also no way to find the volumetric information of a

18、 model,下一页,上一页,返回,Text A,Solid models contain complete information; therefore, not only can they be used to produce engineering drawing, but engineering analysis can be performed on the same model as well. Later, many commercial systems and research systems were developed. Quite a few of these syste

19、ms were based on the PADL and BUILD systems. Although they are powerful in representation, many deficiencies still exist. For example, such systems have extreme computation and resource (memory) requirements, an unconventional way of modeling objects and a lack of tolerance capability have all hinde

20、red CAD applications,下一页,上一页,返回,Text A,It was not until the mid-1980s that solid modelers made their way into the design environment. Today, their use is as common as drafting and wire-frame model application. CAD implementations on personal computers (PCs) have brought CAD to the masses. This devel

21、opment has made CAD available and affordable. CAD originally was a tool used only by aerospace and other major industrial corporation. The introduction of PC CAD packages, such as, AutoCAD, VersaCAD, CAD systems. By 1988, more than 100,000 PC CAD Packages had been sold,下一页,上一页,返回,Text A,Today, PC-ba

22、sed solid modelers are available and are becoming increasingly popular. Because rapid developments in microcomputers have enabled PCs to carry the heavy computational load necessary for solid modeling, many solid graphics user interface (GUI), CAD systems can be ported easily from one computer to an

23、other, most major CAD systems are able to run on a variety of platforms. There is little difference between mainframe, workstation, and PC-based CAD systems,上一页,返回,Notes,1. MIT (Massachusetts Institute of Technology) 马萨诸塞理,返回,Notes,2. Sage project Sage系统,返回,Notes,3. This coincidentally happened at a

24、bout the same time that NC and APT(Automatically Programmed Tool) first appeared 译文：CAD与初次出现的NC和APT（自动编程工具）碰巧同时问世。 Coincidentally为插入语，at about the same time为介词短语，可译为“几乎、同时,返回,Notes,4. An interesting note is that an X-Y plotter has the same basic structure as a NC drilling machine except that a pen i

25、s substituted for the tool on NC spindle. 译文：一个有趣的现象时X-Y绘图仪与NC钻床具有相同的基本结构，除了绘图笔被NC机床上的主轴刀具替代之外。 the same as “与相同”，as为介词，引导短语,返回,Supplementary Reading,CAM and Applications When a design has frozen, manufacturing can begin. Computers have an important role to play in many aspects of production. Numeri

26、cally controlled (NC) machine tools need a part program to define the components being made; computer techniques exist to assist, and in some cases virtually automate the generation of part programs. Modem shipbuilding fabricates structures from welded steel plates that are cut from a large steel sh

27、eet,下一页,返回,Supplementary Reading,Computer-controlled flame cutters are often used for this task and the computer is used to calculate the optimum layout of the components to minimize waste metal. Numerically controlled pipe-routing software. Printed circuit board assembly can also be improved by com

28、puter methods. Quality is maintained by computer-controlled automatic test equipment that diagnoses faults in a particular board and rejects defective boards from the assembly line. Computers are used extensively to plot the artwork used to etch printed circuit boards and also to produce part progra

29、ms for NC drilling machines,下一页,上一页,返回,Supplementary Reading,One of the most important manufacturing function is stock and production control. If the original design is done on a computer, obtaining lists of material requirements is straightforward. Standard computer data processing methods are empl

30、oyed to organize the work flow and order components when required (Fig. 7-1,下一页,上一页,返回,Fig. 7-1,返回,Fig. 7-1 The block diagram of a CAD/CAM system,Supplementary Reading,Part geometry requires calculation of a large number of tool positions. Part programming software is usually incorporated into a fam

31、ily of CAM (Computer Aided Manufacturing ) software. Some CAM software is associated with CAD (Computer Aided Design) software into CAD/Cam stations. Then the CAM software can use the CAD files as a source of data, which speeds up the programming process,下一页,上一页,返回,Supplementary Reading,Part program

32、ming software is user-friendly, meaning the programmer does not have to know the computer programming language or its operating system. It uses screen menus to lead the user through the programming process. Data can be entered via the keyboard, the mouse, or the function keys. Experienced programmer

33、s can use built-in macro capabilities and advanced techniques such as a family of parts to become even more productive,下一页,上一页,返回,Supplementary Reading,Programming software has a dynamic graphics database to hold the actual machining sequences. These sequences can be viewed, edited, chained, or dele

34、ted. The programming can be accomplished whether single cuts or CNC machine canned cycle will be used. The software will also automatically calculate the proper feeds and speeds to be used during the machining, create a tooling list, and define the tool path,下一页,上一页,返回,Supplementary Reading,Programm

35、ers can use different layers to associate with each profile being created or to construct clamps and fixtures to get a complete picture of the part setup. The tool motion can be seen as it will occur at the machine. Using part programming software, the programmer can easily solve trigonometry proble

36、ms to define an accurate tool path. When the program is done, the programmer can send it from the PC to the machine via a communication channel using built-in software with communications capability. Good part programming software is capable of,下一页,上一页,返回,Supplementary Reading,1) Establish the machi

37、ning parameters and tooling for a particular machine or job. (2) Defining the geometry and tool path. (3) Code generation, enabling the programmer to use standard communications protocols or create his or her own,上一页,返回,Translating Skills 7,数词的译法 科技英语中大量出现表示数量、倍数增减的词语，如表71所示，在翻译时要特别注意英汉两种语言表达方式的异同。

38、I数的单位 旧式英国英语（old-fashioned British English）中，十亿不用Billion而用one thousand million表示；现代英语不论美国或英国，都用billion表示 “十亿”，用trillion表示兆,下一页,返回,表71,返回,表71英语中表示数量的词语,Translating Skills 7,II as large as +数词，可译成“大到（至）”； as many as+数词，可译成“多达”； as high as +数词，可译成“高达”； as heavy as+数词，要译成“重达”； as low as +数词，可译成“低到（至）”；

39、以此类推。 The temperature at the suns center is as high as 10,000,000. 太阳中心的温度高达1000万摄氏度。 At night the temperature on the noon may be as low as -160. 夜间，月球上的温度可低至零下160,下一页,上一页,返回,Translating Skills 7,The Nanjing Yangtze River Bridge is as long as 6,700 meters. 南京长江大桥长达6700米。 The outer portion of the whe

40、el may travel as fast as 600 miles per hour. 轮子外缘的速度可能高达每小时600英里。 III.倍数的比较 结构的译法,下一页,上一页,返回,Translating Skills 7,上述三种句型，虽然其结构各不相同，但所表达的概念完全一样。因此，在译成汉语时彼此之间没有区别。三种结构可译成A的大小（长度，重量）是B的N倍。或A比B大（长，重）（N-1）倍。 A yard is three times longer than a foot. 一码等于3英尺。（直译：一码的长度是一英尺的3倍。） The oxygen atom is 16 times

41、heavier than the hydrogen atom. 氧原子的重量是氢原子的16倍。 Mercury weighs more than water by about 14 times. 水银比水重约13倍,下一页,上一页,返回,Translating Skills 7,In case of electronic scanning the beam width is broader by a factor of two. 电子扫描时，波束宽度展宽一倍。（by a factor of tow=by twice） This substance reacts three times as f

42、ast as the other one. 这一物质的反应速度比另一物质快两倍。 IV倍数的增加 结构的译法,下一页,上一页,返回,Translating Skills 7,double可译成“增加一倍”或“翻一番”； treble可译成“增加两倍”或“增加到三倍”； quadruple可译成“增加三倍”或“翻两番”； Wherever we double the force on a given object, we double the acceleration. 每当作用在某一个物体上的力增加一倍时，加速度就增加一倍。 The world population is doubling e

43、very thirty-five years. 世界人口的数量每隔35年就翻一番。 As the high voltage was abruptly trebled, all the valves burnt. 由于高压突然增加了两倍，管子都烧坏了,下一页,上一页,返回,Translating Skills 7,结构的译法 上述五种结构虽然形式有所不同，但所表达的概念完全一致。它们都表示“乘以N”、“成N倍”这一概念，因此，应译成“增加到N倍”或“增加了（N-1）倍”。 The output of coal has been increased three times as against 1

44、983. 煤产量比1983年增长了两倍,下一页,上一页,返回,Translating Skills 7,In 1987, the total output valve of the textile industry increased to four times compared with 1977. 1987年纺织工业总产量同1977年相比，增长了3倍。 A temperature rise of 100 increases the conductivity of a semiconductor by 50 times. 温度升高100,半导体的电导率就增加到50倍。 If X is dou

45、bled, Y is increased by a factor of 4. 若X增加到两倍，则Y增加到4倍。 将increase 换成其他表示“增加”“超过”“升高”等动词，其译法也是如此,下一页,上一页,返回,Translating Skills 7,The speed exceeds the average speed by a factor of 3.5. 该速度超过平均速度两倍半。 The sales of industrial electronic products have multiplied six times. 工业电子产品的销售额增加了五倍。 After the powe

46、r is generated at 11,000 volts, it is sent into transformers that step up the voltage 25 times to 275,000 volts. 电力以11，000伏电压产生以后，就被送进变压器增压至25倍，达到275，000伏,下一页,上一页,返回,Translating Skills 7,结构的译法 As much (many) again as与again as much (many) as 这两种结构可译成“是的两倍”或“比多一倍半”、“比多半倍”，或“比多一半”。 This year we have pr

47、oduced as many TV sets again as compared with last year. 今年我厂生产的电视机比去年多一倍,下一页,上一页,返回,Translating Skills 7,The amount left was estimated to be again as much as all the zinc that has been mined. 当时估计，剩余的锌储量是已开采量的两倍。 Wheel A turns half as fast again as Wheel B. A 轮转动比B轮快一半。 The resistance of aluminium

48、is approximately half again as great as that of copper for the same dimensions. 尺寸相同时，铝的电阻约为铜的一倍半,下一页,上一页,返回,Translating Skills 7,V. 倍数的的减少 结构的译法,下一页,上一页,返回,Translating Skills 7,上述七种结构形式虽然有所不同，但所表达的概念则完全一 样。译成汉语均为“减少了n-1/n”或减少到1/n”。由于汉语中 不习惯讲“减少了若干倍”，而说“减少了几分之几”。翻译时， 应将N倍换算成 或 ，例如：reduce 3 times 可换算

49、成 或 ， 即可译成“减少了三分之二”或“减少到三分之一。”此外，汉 语的分母不习惯用小数，倘若英语的倍数为小数，则应化成 整数进行换算。例如：reduce 3.5 times 应换算成 或 ，即 可译成“减少了七分之五”或“减少到七分之二,下一页,上一页,返回,Translating Skills 7,上面所列结构中，除reduce外，还有一些表现“减少”的同义词，近义词，如decrease, shorten, drop, step-down, cut down等。在N times less than 结构中，less可换成其他比较级的词，如lighter, weaker, shorter等

50、。 The new equipment will reduce the error probability by seven times. 新设备的误差概率将降低七分之六。 The voltage has dropped five times. 电压降低了五分之四。（电压为原来的五分之一。） Tests indicate this might reduce activity by a factor between 10 and 100. 测试结果表明，这可将放射性降低到原来的1/101/100,下一页,上一页,返回,Translating Skills 7,The leads of the new