《机械专业英语》课件第23章.ppt

1、Unit 23TEXT LEARN TO SPEAK NEW WORDS AND PHRASES NOTES EXERCISES READING MATERIAL PROFESSIONAL WORDS AND PHRASES TEXTPart Programming A part programmer is a very crucial person in any NC manufacturing system.On obtaining the component drawing,he decides the sequence of operations,the speeds and feed

2、s for the various operations and determines the magnitude of various motions desired.Therefore,it is important that he should be familiar with the various operations and machine tools to be used.He should be able to carry out calculations based on geometry and trigonometry.Data Required for Programm

3、ing To prepare the manuscript for manual part programming,the programmer needs to collect some data pertaining to the work to be carried out.This data would be as follows:(1)Machine tools specifications.(2)Specification of all tools.(3)Specification of work material.(4)Speed feed tables.Paper tape T

4、he most common type of tape used in NC is the paper tape,being inexpensive.However,mylar plastic tapes or plastic coated paper tapes are also used in production practice.The standard width of the tape is 25.4mm and the number of channels 8.EIA/ISO Code For coding on the tape,EIA or ISO codes are fol

5、lowed.NC machines are generally equipped to handle both types of information.Nowadays mostly ISO codes are used.The information given here pertains to his code only.The numerical information is distinguished by holes in channels 5and 6,while alphabetical characters are distinguished by holes in chan

6、nel 7.Holes punched on channel 8 refer to parity.As per ISO code,the number of holes in a row should be an even number.That is,to express numerical value 4,holes need to be punched in channels 3,4,5 and 8.However for value 9,holes would only be in channels 1,4,5 and 6.Tape Formats The information ab

7、out an operation which would be necessary to be conveyed to the controller for the machine tool operation would consist of the following:(1)Operation number.(2)Operation code.(3)Coordinates for position or motion.(4)Tool information.(5)Speed and feed for operation.(6)Miscellaneous information like o

8、n/off,spindle clockwise or anti-clockwise rotation,constant off/on etc.In a program this entire information is called block.There are 3 types of formats for representing the block in punched tape.(1)Fixed sequential format.(2)Word address format.(3)Tab sequential format.The following are the letter

9、addresses used in programming:N operation sequence number address.G preparatory function address.X,Y,Z,A,B,C dimension address.S spindle speed address.F feed rate address.T tool address.M miscellaneous function address.Preparatory Function This information is given by a word which is prefixed by the

10、 letter G followed by the numerical code for the operation for which the control unit is to instruct the machine tool.For example,G81 means that the instruction is to drill.The other parameters necessary for carrying out the operation would follow.The Gwill not be able to operate the machine tool un

11、til all the relevant information,which follows is processed.Absolute and incremental preparatory function Preparatory function G90 and G91 are used for specifying that the data in the following block is in absolute mode(relative to a common datum)or incremental mode(relative to current position)resp

12、ectively.G90 can be cancelled by G91 or vice versa.Miscellaneous Function For carrying out some operation,it may be desirable to start the spindle and have its rotation clockwise or anticlockwise.Words used for such instruction are termed as miscellaneous functions.Similarly,starting or stopping the

13、 coolant also fall under this category.These instructions are not pertaining to dimensions of the work but are required for carrying out the operation.The machine tools responds information is prefixed by the alphabet M followed by the numerical code for the function required.For example,M03 would m

14、ean spindle to rotate colckwise,while M04 anticlockwise.LEARN TO SPEAKLi Ying:Good afternoon,Mr.Wang.Mr.Wang:Good afternoon,Li Ying.Where are you going?Li Ying:I am going to the library to borrow some books.Mr.Wang:What kinds of book do you want to borrow?Li Ying:I would like to borrow some books of

15、 part programmer.Mr.Wang:Why?Li Ying:I have been learning the course of part programmer,but I have some trouble in it.So I need some reference books.Mr.Wang:What are the problems?May I help you?Li Ying:Yes,what are the EIA/ISO Code?Mr.Wang:NC machines are generally equipped to handle both types of i

16、nformation.Nowadays mostly ISO codes are used.The information given here pertains to his code only.The numerical information is distinguished by holes in channels 5and 6,while alphabetical characters are distinguished by holes in channel 7.Holes punched on channel 8 refer to parity.As per ISO code,t

17、he number of holes in a row should be an even number.That is,to express numerical value 4,holes need to be punched in channels 3,4,5 and 8.However for value 9,holes would only be in channels 1,4,5 and 6.Li Ying:Oh,I think I will like it in the future.You are very kind.Bye-bye.Mr.Wang:Bye.NEW WORDS A

18、ND PHRASES programmer n.编程员 parity n.奇偶校验 component drawing 零件图 paper tape 纸带 even number 偶数 tape format 纸带格式 operation code 操作码 word address 字地址 letter address 字母地址 preparatory function 准备功能 absolute mode 绝对方式 incremental mode 增量方式 miscellaneous function 辅助(杂项)功能 anti-clockwise(anticlockwise)逆时针 NO

19、TES1Therefore,it is important that he should be familiar with the various operations and machine tools to be used.因此，他(编程员)应熟悉各种加工和所用机床，这一点很重要。It is+adj.+that clause,主语从句。2To prepare the manuscript for manual part programming,the programmer needs to collect some data pertaining to the work to be car

20、ried out.为了给零件手工编程准备好草稿，编程员需要收集与零件加工相关的资料。to prepare引导目的状语；carry out意为执行，施行。3As per ISO code,the number of holes in a row should be an even number.That is,to expressnumerical value 4,holes need to be punched in channels 3,4,5 and 8.按照按照ISO 标准，每一行的孔数应为偶数。也就是说，要标准，每一行的孔数应为偶数。也就是说，要表示数字表示数字4，就要在，就要在3、4

21、、5和和8通道穿孔。通道穿孔。4The information about an operation which would be necessary to be conveyed to the controller for the machine tool operation would consist of the following:必须传送给控制装置的与机床操作有关的信息如下：必须传送给控制装置的与机床操作有关的信息如下：about an operation是是information的定语，其后又有的定语，其后又有一个由一个由which 引导的定语从句。引导的定语从句。EXERCISE

22、S 1Translate the following expressions into Chinese:(1)part programmer (2)component drawing (3)geometry and trigonometry (4)manual part programming (5)punched paper tape (6)preparatory function (7)miscellaneous function (8)absolute mode (9)incremental mode (10)clockwise direction and anticlockwise d

23、irection 2There are a few preparatory and miscellenous functions,translate and recite them:G00 positioning G01 linear interpolation G02 clockwise circular interpolation(CW)G03 anticlockwise circular interpolation(CCW)G90 absolute data G91 incremental data M00 program stop M02 end of program 3Transla

24、te the following passage into Chinese:A numerical control machine is a machine positioned automatically along a preprogrammed path by means of coded instructions.So,some has to determine what operations the machine is to perform and put that the information into a coded form that the NC control unit

25、 understands before the machine can do anything.Machine may be programmed manually or with the aid of a computer.Manually programming is called manual part programming,and programming done by a computer is called computer aided programming(CAP).READING MATERIALProgramming for NC A program for numeri

26、cal control consists of a sequence of directions that caused a NC machine to carry out a certain operation,machining being the most commonly used process.Programming for NC may be done by an internal programming department,on the shop floor,or purchased from an outside source.Also,programming may be

27、 done manually or with computer assistance.The program contains instructions and commands.Geometric instructions pertain to relative movements between the tool and the work piece.Processing instructions pertain to spindle speeds,feeds,tools,and so on.Travel instructions pertain to the type of interp

28、olation and slow or rapid movements of the tool or worktable.Switching commands pertain to on/off position for coolant supplies,spindle rotation,direction of spindle rotation,tool changes,workpiece feeding,clamping,and so on.(1)Manual programming.Manual part programming consists of first calculating

29、 dimensional relationships of the tool,workpiece,and worktable,based on the engineering drawings of the part,and manufacturing operations to be performed and their sequence.A program sheet is then prepared,which consists of the necessary information to carry out the operation,such as cutting tools,s

30、pindle speeds,feeds,depth of cut,cutting fluids,power,and tool or workpiece relative positions and movements.Based on this information,the part program is prepared.Usually a paper tape is first prepared for trying out and debugging the program.Depending on how often it is to be used,the tape may be

31、made of more durable mylar.Someone knowledgeable about the particular process and able to understand,read,and change part programs can do manual programming.Because they are familiar with machine tools and process capabilities,skilled machinists can do manual programming with some training in progra

32、mming,however,the work is tedious,and time consuming,and uneconomical and is used mostly in simple point-to-point applications.(2)Computer Aided Programming.Computer aided part programming involves special symbolic programming languages that determine the coordinate points of corners,edges,and surfa

33、ces of the part.Because numerical control involves the insertion of data concerning workpiece materials and processing parameters,programming must be done by operators or programmers who are knowledgeable about the relevant aspects of the manufacturing processes being used.Before production begins,p

34、rograms should be verified,either by viewing a simulation of the procession on a CRT screen or by making the part from an inexpensive material,such as aluminum,wood,or plastic,rather than the material specified for the finished part.PROFESSIONAL WORDS AND PHRASES sequence n.继(连)续，一连串 instruction n.指令，命令 command n.命令 debug vt.调试 durable adj.持久的，耐用的 mylar n.聚脂薄膜 tedious adj.单调乏味的 coordinate n.坐标 relevant adj.有关的 simulation n.仿真,模拟 shop floor 车间 point-to-point 点对点 processing parameter 加工参数