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CAMandCNCCAMsystemshavechangedthejoboftheCNCprogrammerfromonemanuallyproducingCNCcodetoonemaximizingtheoutputofCNCmachines.SinceCNCmachinetoolsaremadebyagreatnumberofmanufacturers,manydifferentCNCcontrolunitsareinuse.Controlunitsfromdifferentmanufacturersuseavarietyofprogramformatsandcodes.ManyCNCcodewordsareidenticalfordifferentcontrollers,butagreatnumbervaryfromonetoanother.ToproduceanidenticalpartonCNCmachinetoolswithdifferentcontrollerssuchasonebyFANCU,OKUMAorDYNAPATH,wouldrequirecompletelydifferentCNCcodes.EachmanufacturerisconstantlyimprovingandupdatingitsCNCcontrollers.Theseimprovementsoftenincludeadditionalcodewordspluschangesinhowtheexistingcodeworks.ACAMsystemsallowstheCNCprogrammertoconcentrateonthecreationofanefficientmachiningprocess,ratherthenrelearningchangedcodeformats.ACNCprogrammerlooksattheprintofapartandthenplansthesequenceofmachiningoperationsnecessarytomakeit(FigureO-3).Thisplanincludeseverything,fromtheselectionofpossibleCNCmachinetools,towhichtoolingtouse,tohowthepartisheldwhilemachiningtakesplace.TheCNCprogrammerhastohaveathoroughunderstandingofallthecapacitiesandlimitationsoftheCNCmachinetoolsthataprogramistobemadefor.Machinespecificationssuchashorsepower,maximumspindlespeeds,workpieceweightandsizelimitations,andtoolchangercapacityarejustsomeoftheconsiderationsthataffectprogramming.Anotherareaofmajorimportancetotheprogrammeristheknowledgeofmachiningprocesses.Anexamplewouldbetheselectionofthesurfacefinishrequirementspecifiedinthepartprint.Thesequenceofmachiningprocessesiscriticaltoobtainacceptableresults.Cuttingtoollimitationshavetobeconsideredandthisrequiresknowledgeofcuttingtoolmaterials,tooltypes,andapplicationrecommendations.Agoodprogrammerwillspendaconsiderableamountoftimeinresearchingtherapidlygrowingvolumeofnewandimprovedtoolsandtoolmaterials.Oftenthetoolthatwasonthecuttingedgeoftechnologyjusttwoyearsagoisnowobsolete.Informationonnewtoolscancomefromcatalogsortoolmanufacturers'toolingengineers.Helpintoolselectionoroptimumtoolworkingconditionscanalsobeobtainedfromtoolmanufacturersoftware.ExampleswouldbeKennametal's"TOOLPRO",softwaredesignedtohelpselectthebesttoolgrade,speed,andfeedratesfordifferentworkmaterialsinturningapplication.Anotherveryimportantfeatureof"TOOLPRO"isthedisplayofthehorsepowerrequirementforeachmachiningselection.Thisallowtheprogrammertoselectacombinationofcuttingspeed,feedrate,anddepthofcutthatequalsthemachine'smaximumhorsepowerforroughingcuts.Forafinishingcut,thesmallestdiameterofthepartbeingmachinedisselectedandthenthecuttingspeedvarieduntiltheRPMisequaltothemaximumRPMofthemachine.Thishelpsinmaximizingmachiningefficiency.Knowingthehorsepowerrequirementforacutiscriticalifmorethanonetooliscuttingatthesametime.SoftwareforamachiningcenterapplicationwouldbeIngersollToolCompany's"ActualChipThickness",aprogramusedtocalculatethechipthicknessinrelationtofeed-per-toothforamillingcutter,especiallyduringashallowfinishingcut.Ingersoll's"RigidityAnalysis"softwareealculatestooldeflectionforendmillsasafunctionoftoolstiffnessandtoolforce.Tothispointwelookedatsomegeneralqualificationsthataprogrammershouldpossess.NowweexaminehowaCAMsystemworks.PointControlCompany'sSmartCamsystemusesthefollowingapproach.First,theprogrammermakesamentalmodeloftheparttobemachined.Thisincludesthekindofmachiningtobeperformed-turningormilling.Thenthepartprintisstudiedtodevelopamachiningsequence,roughingandfinishingcuts,drilling,tapping,andboringoperations.Whatwork-holdingdeviceistobeused,aviseorfixtureorclamps?Aftertheseconsiderations,computerinputcanbestarted.FirstcomesthecreationofaJOBPLAN.ThisJOBPLANconsistsofentriessuchasinchormetricunits,machinetype,partID,typeofworkpiecematerial,setupnotes,andadescriptionoftherequiredtools.Thislineofinformationdescribesthetoolbynumber,type,andsizeandincludestheappropriatecuttingspeedandfeedrate.Afteralltheselectedtoolsareentered,thefileissaved.Thesecondprogrammingstepisthemakingofthepart.Thisrepresentsagraphicmodelingoftheprojectedmachiningoperation.AfterselectingatoolfromthepreparedJOBPLAN,parametersforthecuttingoperationareentered.Foradrill,oncethecoordinatelocationoftheholeandthedeptharegiven,acircleappearsonthatspot.Ifthelocationisincorrect,theUNDOcommanderasesthisentryandallowsyoutogivenewvaluesforthisoperation.Whenanendmillisbeingused,cuttingmovements(toolpath)areusuallydefinedaslinesandarcs.Asalineisprogrammed,thetoolpathisgraphicallydisplayedanderrorscanbecorrectedinstantly.Atanytimeduringprogramming,thecommandSHOWPATHwillshowtheactualtoolpathforeachoftheprogrammedtools.Thetoolswillbedisplayedinthesequenceinwhichtheywillbeusedduringactualmachining.Ifthesequenceofatoolmovementneedstobechanged,afewkeystrokeswilltothat.SometimesinCAMtheprogrammingsequenceisdifferentfromtheactualmachiningorder.Anexamplewouldbethemachiningofapocketinapart.WithCAM,thefinishedpocketoutlineisprogrammedfirst,thenthisoutlineisusedtodefinetheroughingcutstomachinethepocket.Theroughingcutsarecomputergeneratedfrominputssuchasdepthandwidthofcutandhowmuchmaterialtoleaveforthefinishcut.Differentroughingpatternscanbetriedouttoallowtheprogrammertoselectthemostefllcientonefortheactualmachiningcuts.Sinceeachtoolisrepresentedbyadifferentcolor,itiseasytoobservethetoolpathmadebyeachone.ACAMsystemletstheprogrammerviewthegraphicsmodelfromvaryingangles,suchasatop,front,side,orisometricview.Atoolpaththatlookscorrectfromatopview,mayshowfromafrontviewthatthedepthofthecuttingtoolisincorrect.Changescaneasilybemadeandseenimmediately.Whenthetoolpathandthesequenceofoperationsaresatisfactory,machinereadycodehastobemade.ThisisaseasyasspecifyingtheCNCmachinethatistobeusedtomachinethepart.ThecodegeneratorforthatspecificCNCmachineduringprocessingaccessesfourdifferentfiles.TheJOBPLANfileforthetoolinformationandtheGRAPHICEfileforthetoolpathandcuttingsequence.ItalsousestheMACHINEDEFINEfilewhichdefinestheCNCcodewordsforthatspecificmachine.Thisfilealsosuppliesdataformaximumfeedrates,RPM,toolchangetimes,andsoon.ThefourthfiletakingpartinthecodegeneratingprocessistheTEMPLATEfile.ThisfileactslikearulerthatproducestheCNCcodewithallofitspartsintherightplaceandsequence.Whenthecodegenerationiscomplete,aprojectedmachiningtimeisdisplayed.Thistimeiscalculatedfromvaluessuchasfeedratesanddistancestraveled,noncuttingmovementsatmaximumfeedratesbetweenpoints,toolchangetimes,andsoon.Theprojectedmachiningtimecanberevisedbychangingtoolingtoallowforhighermetalremovalratesorcreatingamoreefficienttoolpath.Thisdisplayoftotaltimerequiredcanalsobeusedtoestimateproductioncosts.IfmorethenoneCNCmachinetoolisavailabletomachinethispart,makingcodeandcomparingthemachiningtimemayshowthatonemachineismoreefficientthantheothers.CAM和CNCCAM系统改变了CNC程序员的工作，即从手工编制CNC代码到CNC车床的输出最大值。自从手工CNC车床被一大批厂家生产以来，许多不同的CNC控制单元就被使用了。各个不同的厂家的控制单元使用各个不相同的程序与代码。许多CNC代码语句可被不同的控制器识别。但其间还有众多的区别。为了在有着不同控制器（如FAWC、OKUMA、或DYNAPATH）生产一个可互换的零件，将需要完全不同的CNC代码。每个制造商在不断地提高和更新其CNC控制。这些改进通常包括附加的代码语句在已有代码如何工作上的变化。CAM系统允许CNC程序员在高效的加工过程的建立上浓缩、精选、而不重新学习已改变的代码格式。一个CNC程序员看着一个零件的图纸，并且设计必要的车床操作来制造这个零件（如图O-3）。这个设计包括以下每个因素，从可能使用的CNC车床的选择，到车床的使用选择，再到加工时的零件装夹的选择。CNC程序员必须对这个即将写入程序的CNC车床的能力和局限有一个完全的了解。车床主参数如马力主轴马力、最大转速、工作台的重量、工具的尺寸限制、加工变化能力等只是值得考虑的影响程序的因素中的一些。对程序员要求的另一个最重要领域是制造过程的知识。举例如选择最佳的切削工具来完成零件图上所标的公差和表面光洁度。这个加工过程的程序是吹毛求疵地获得符合的结果。车床极限能力必须考虑全面，这就需要刀具材料，刀具类型，和其推荐应用的知识。一个优秀的程序员将花相当数量的时间来研究关于新的、改进的刀具和刀具材料的快速设计者发表的书籍。通常在切削方面使用两年前的技术的刀具现在就是落后的。新刀具的信息来自手册或刀具制造商的刀具之资料。刀具选择或最佳刀具工作条件的帮助同样可在刀具制造商的软件中获得。例如：Kennametal’s被设计来帮助不同的使用其车间的工厂选择最佳的车床；“TOOCPRO”的另一个很重要的特征是为每个车床选择马力需求等等这些就允许设计者选择一个结合了切削速度、进给率和切削深度等因素的车床。这就胜任于粗选中最佳马力的选择。对于光洁度的加工，零件在加工中最小进给量被选定，接着切削速度直到转速与车床的最佳转速相等时才不变。这就帮助最大提高了车床效率。如果不只一台车床在同时工作的话了解一台车床的功率需求是必要的。为加工中心使用的软件是ENGERSOLLCUTTINGTOOL公司的ACTUALCHIPTHICKNESS。程序被用来计算磨床每次进的给量，特别是在微量的光洁度加工中。ENGERSOLL的“精密分析”软件作为车床刚度和车床力的功能来。在这一点上我们观察一些广泛的设计人员应掌握的规格。现在我们测试CAM系统怎样工作。点控公司（POINTCPNTROLLCOMPANY）的SMARTCAM系统使用接下来的手段：首先设计人员使用一个金属零件模型去加工。这包括的加工方式是------车或磨。接着这个零件图被研究来做成车床加工工序，粗加工或精加工、钻、冲、磨等操作。被使用的装夹夹具是虎钳，抓盘还是卡盘？这些考虑之后，计算机输出就可开始了。首先还是工艺卡的建立。这个工艺卡由各种记录（例如：英制或公制，车床类型、零件卡、切削材料类型、安装记录、和所需要车床的描述其第二个编程的步骤是零件的制造。这描述了一个所设计车床操作的生动模型。从已准备好的JOBPLAN中选好车床后，切削加工的参数就被编入。对钻床而言，一旦孔的位置坐标和深度被给出，一个孔就给出现在那点。如果其位置是错的，其撤消命令选择这一记录，并允许你给这个工序新的值。当端面磨时，切削运动通常被定义为弧。当一条直线被编入程序，TOOLPATH就会生动的显示，其错误也可立即被纠正。在程序运行的任意时刻，命令SHOWPATH会显示当前的刀具轨迹，也会显示刀具在实际加工时的使用顺序。当刀具运动顺序需要改变时，可用一个按键来实现它。有时，CAM的程序顺序和实际加工的顺序是各不相同的。某部件的孔的加工就是一个例子。首先，在CAM中编译已加工孔的外部轮廓，再把外部轮廓当成粗基准来加工内孔。根据输入切削的宽和深以及完成切削需切去的材料，计算机产生粗切削的加工程序。程序员尝试各种粗基准，以便选出最有效的切削加工方法。

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