机械类英文翻译(CNC计划编程).docx

编号：时间：2021 年 x 月 x 日书山有路勤为径，学海无涯苦作舟书山有路勤为径，学海无涯苦作舟页码：第1页 共9页第 1 页 共 9 页From Peter Smid,CNC Programming Handbook:A Comprehensive Guide to PracticalCNC Programming,Second Edition,Industrial Press,Inc.200 Madison Avenue,New York,2003.CHAPTER 6:PROGRAMMING PLANNINGThe development of any CNC program begins with a very carefully planned process.Such aprocess starts with the engineering drawing of the required part.Before the part is machined,several steps have to considered and carefully evaluated.The more effort is put into the planningstage of the program,the better results may be expected at the end.STEPS IN PROGRAM PLANNINGThe steps required in program planning are decided by the nature of the work.There is noformula for all the jobs,but some basic steps should be considered:*Initial information/Machine tools features*Part complexity*Manual programming/computerized programming*Typical programming procedure*Part drawing/Engineering data*Methods sheet/Materials specifications*Machining sequence*Tooling selection*Part setup*Technological decisions*Work sketch and calculations*Quality considerations in CNC programmingThe steps in the list are suggestions only a guideline.They are quite flexible and shouldalways be adapted for each job and to the specific conditions of the work.INITIAL INFORMATIONMost drawings define only the shape and size of the completed part and normally do notspecify data about the initial blank material.For programming,a good knowledge of the materialis an essential start-mainly in terms of its size,type,shape,condition,hardness,etc.The drawingand material data are the primary information about the part.At this point,CNC program can beplanned.The objective of such a plan is to use the initial information and establish the mostefficient method of machining,with all related consideration mainly part accuracy,productivity,safety and convenience.The initial part information is not limited to the drawing and the material data,it alsoincludes conditions not covered in the drawing,such as pro-and post-machining,grindingallowances,assembly features,requirements for hardening,next machine setup,and others.Collecting all this information provides enough material to start planning the CNC program.MACHINE TOOLS FEATURESNo amount of initial information is useful if the CNC machine is not suitable for the job.During program planning,programmer concentrates on a particular machine tool,using aparticular CNC system.Each part has to be setup in a fixture,the CNC machine has to be largeenough to handle the size of the part,the part should not be heavier than the maximum weightallowed.The control system must be capable to provide the needed tool path,and so on.In the编号：时间：2021 年 x 月 x 日书山有路勤为径，学海无涯苦作舟书山有路勤为径，学海无涯苦作舟页码：第2页 共9页第 2 页 共 9 页most cases,the CNC equipment is already available in the shop.Very few companies go and buy anew CNC machine just to suit a particular job.Such cases are rather rare and happen on if theymake economic sense.*Machine Type and SizeThe most important considerations in program planning are the type and the size of the CNCmachine,particularly its work space or work area.Other features,equally important,are themachine power rating,spindle speed and feed rate range,number of tool stations,tool changingsystem,available accessories,etc.Typically,small CNC machines have higher spindle speeds andlower power rating,large machines have lower spindle speeds available,but their power rating ishigher.*Control SystemThe control system is the heart of a CNC machine.Being familiar with all the standard andoptional features available on the control is a must.This knowledge allows the use of a variety ofadvanced programming methods,such as the machining cycles,subprograms,macros and othertimesaving features of a modern CNC system.A programmer does not have to physically run a CNC machine.Yet,the programs willbecome better and more creative with good understanding of the machine and its control system.Program development reflects programmers knowledge of the CNC machine operation.One of the main concerns in program planning should be the operators perception of theprogram.To a large degree,such a perception is quite subjective,in the sense that differentoperators will express their personal preferences.On the other hand,every operator appreciates anerr-free,concise,well-documented and professionally prepared part program,consistently and oneafter another.A poorly designed program is disliked by any operator,regardless of personalpreferences.PART COMPLEXITYAt the time the drawing,material and the available CNC equipment are evaluated,thecomplexity of the programming task becomes much clearer.How difficult is to program the partmanually?What are the capabilities of the machines?What are the costs?Many questions have tobe answered before starting the program.Simple programming jobs may be assigned to a less experienced programmer of the CNCoperator.It makes sense from the management perspective and it is also a good way to gainexperience.Difficult or complex jobs will benefit from a computerized programming system.Technologies such as Computer Aided Design(CAD)and Computer Aided Manufacturing(CAM)have been a strong part of the manufacturing process for many years.The cost of a CAD/CAMsystem is only a fraction of what it used to be only a few years ago.Even small shops now findthat the benefits offered by modern technology are too significant to be ignored.Severalprogramming systems are available various computers and can handle any job.For a typicalmachine shop,a Windows based programming software can be very beneficial.A typical exampleof this kind of application is the very popular and powerful MasterCAM,form CNC Software,Inc.Tolland.CT.There are several others.MANUAL PROGRAMMINGManual programming(without a computer)has the most common method of preparing a part编号：时间：2021 年 x 月 x 日书山有路勤为径，学海无涯苦作舟书山有路勤为径，学海无涯苦作舟页码：第3页 共9页第 3 页 共 9 页program for many years.The latest CNC controls make manual programming much easier thanever before by using fixed or repetitive machining cycles,variable type programming,graphic toolmotion simulation,standard mathematical input and other timesaving features.In manualprogramming,all calculations are done by hand with the aid of a pocket calculator nocomputer programming is used.Programmed data can be transferred to the CNC machine via acable,using an inexpensive desktop or a laptop computer.This process is faster and more reliablethan other methods.Short programs can also be entered manually,by keyboard entry,directly atthe machine.A punched tape used to be the popular media of the past but has virtually disappearedfrom machine shops.*DisadvantagesThere are some disadvantages associated with manual programming.Perhaps the mostcommon is the length of time required to actually develop a fully functioning CNC program.Themanual calculation,verification and other related activities in manual programming are very timeconsuming.Other disadvantages,also very high on the list,are a large percentage of errors,a lackof tool path verification,the difficulty is making changes to a program,and many others.*AdvantagesOn the positive side,manual part programming does have quite a few unmatched qualities.Manual programming is so intense that it requires the total involvement of the CNC programmerand yet offers virtually unlimited freedom in the development of the program structure.Programming manually does have some disadvantages,but it teaches a tight discipline andorganization in program development.It forces the programmer to understand programmingtechniques to the last detail.In fact,many useful skill learned in manual programming are directlyapplied to CAD/CAM programming.Programmer has to know what is happening at all times andwhy it is happening.Very important is the in-depth understanding of every detail during theprogram development.Contrary to many beliefs,a thorough knowledge of manual programming methods isabsolutely essential for efficient management of CAD/CAM programming.CAD/CAM AND CNCThe need for important improved efficiency and accuracy in CNC programming has been themajor reason for development of a variety of methods that use a computer to prepare partprograms.Computer assisted CNC programming has been around for many years.First,in theform of language based programming,such as APT or Compact.Since the late 1970s,CAD/CAM has played a significant role by adding the visual aspect to the programming process.The acronym CAD/CAM means Computer Aided Design and Computer Aided Manufacturing.The first three letters(CAD)cover the area of engineering design and drafting.The second threeletters(CAM),covers the area of computerize manufacturing,where CNC programming is only asmall part.The whole subject of CAD/CAM covers much more than just design,drafting andprogramming.It is a part of modern technology also known as CIM Computer IntegratedManufacturing.In the area of numerical control,computers have played a major role for a long time.Machine controls have become more sophisticated,incorporating the latest techniques of dataprocessing,storage,tool path graphics,machining cycles,etc.Programs can now be prepared withthe use of inexpensive computers,using graphical interface.Cost is no longer an issue;even small编号：时间：2021 年 x 月 x 日书山有路勤为径，学海无涯苦作舟书山有路勤为径，学海无涯苦作舟页码：第4页 共9页第 4 页 共 9 页machine shops can afford a programming system in house.These systems are also popularbecause of their flexibility.A typical computerized programming system does not have to bededicated only to programming all related tasks,often done by the programmer,can beimplemented on the same computer,for example,cutting tool inventory management,database ofpart programs,material information sheet,setup sheets and tooling sheets,etc.The same computercould also be used for uploading and downloading CNC programs.*IntegrationThe keyword in the acronym CIM is integration.It means putting all the elements ofmanufacturing together and work with them as a single unit and more efficiently.The main ideabehind a successful integration is to avoid duplication.One of the most important rules of using aCAD/CAM computer software is:Never Do Anything Twice!When a drawing is made in a CAD software(such as AutoCAD),then done again in a CAMsoftware(such as MasterCAM),there is a duplication.Duplication breeds errors.In order to avoidduplication,most of the CAD system incorporate a transfer method of the design to the selectedCAM system to be use for CNC programming.Typical transfers are achieved through specialDXF or IGES files.The DXF stands for Data Exchange Files or Drawing Exchange Files,and theIGES abbreviation is a short form of Initial Graphics Exchange Specification files.Once thegeometry is transferred form the CAD system to the CAM system,only the tool path relatedprocess is needed.Using a post processor(special kind of formatter),the computer software willprepare a part program,ready to be loaded directly to the CNC machine.*Future of Manual ProgrammingIt may seem that the manual programming is on the decline.In terms of actual use,this isprobably true.However,it is necessary to keep in perspective that any computerized technology isbased on the already well established methods of manual programming.Manual programming forCNC machines serves as the source of the new technology it is the very elementary concept onwhich the computerized programming is based.This knowledge base opens the door fordevelopment of more powerful hardware and software applications.The manual programming may be use somewhat less frequently today and eventually will beused even less but knowing it well really understanding it is and always will be the key tocontrol the power of CAM software.Even computers cannot do everything.There are somespecial programming projects that a CAM software,regardless of the price,may handle to anabsolute satisfaction.If the control system can handle it,manual programming is the way to theultimate control over such a project,when any other methods may not be suitable.Even with a well customized and organized computerized programming system,how can thegenerated program output be exactly as intended?How can the CNC operator change any part ofthe program on the machine,without knowing its rules and structure?Successful use ofcomputerized programming requires understanding of manual programming methods.TYPICAL PROGRAMMING PROCEDUREPlanning of a CNC program is no different than any other planning;it must be approached ina logical and methodical way.The first decisions relate to what tasks have to be done and whatgoals have to be reached.The other decisions relate to how to achieve the set goals in an efficientand safe manner.Such a progressive method not only isolates individual problems as they develop,it also forces their solution before the next step can be taken.编号：时间：2021 年 x 月 x 日书山有路勤为径，学海无涯苦作舟书山有路勤为径，学海无涯苦作舟页码：第5页 共9页第 5 页 共 9 页The following items form a fairly common and logical sequence of tasks done in CNCprogramming.The items are only in a suggested order,offered for further evaluation.This ordermay be changed to reflect special conditions or working habits.Some items may be missing orredundant:1.Study of initial information(drawing and methods)2.Material stock(blank)evaluation3.Machine tool specifications4.Control system features5.Sequence of machining operations6.Tooling selection and arrangement of cutting tools7.Set of the part8.Technological data(speed,feed rates,etc.)9.Determination of the tool path10.Working sketches and mathematical calculations11.Program writing and preparation for transfer to CNC12.Program testing and debugging13.Program documentationThere is only one goal in CNC program planning and that is the completion of allinstructions in the form of a program that will result in an error-free,safe and efficient CNCmachining.The suggested procedures may require some changes for example,should the toolingbe selected before or after the part setup is determined?Can the manual part programmingmethods be used efficiently?Can the manual part programming methods be used efficiently?Arethe working sketches necessary?Do not be afraid to modify any so called ideal procedure eithertemporarily,for a given job,or permanently,to reflect a particular CNC programming style.Remember,there are no ideal procedures.编号：时间：2021 年 x 月 x 日书山有路勤为径，学海无涯苦作舟书山有路勤为径，学海无涯苦作舟页码：第6页 共9页第 6 页 共 9 页第六章：制定编程计划第六章：制定编程计划编写任何 CNC 程序都必须经过周密计划后开始。这个过程的起点就是所需工件的工程图。在实施工件加工之前一些步骤必须仔细考虑和评估。在程序的计划阶段付出的努力越多，最后预期的结果可能就越好。制定编程计划的步骤制定编程计划的步骤具体采用哪些步骤要根据实际的工作条件而定，没有国定的程式。但还是有一些基本的步骤可供参考：初始信息、机床的加工特性工件的复杂程度手工编程、电脑编程典型的编程工艺工件图纸、工程数据处理表、材料规格加工工序刀具选择工件的夹装技术要求工程草图和计算编程要达到的质量要求这些建议只是提供了一点基本的方向。具体的应用变化很多，必须根据对应的加工和工作特定的条件灵活的调整。初始信息初始信息大多数工程图只是定义了零件的形状和尺寸，一般不标明最初毛坯料的数据。对于编程来说，基本的起点是对原材料的掌握，诸如尺寸、形状、硬度、加工性能等等。对于工件来说最主要的信息就是工程图和原材料数据，在这基础上程序才得于建立。这个计划的目的就是利用最初的信息去建立最高效的加工方法，要考虑到所有的相关事项主要是工件的精度、生产率、安全性和方便性。最初的工件信息并不限于零件图的材料信息，它还包括一些没有涵盖在零件图中的内容，比如前加工和后加工、磨削余量、装配特点、