lesson-6-numerical-control-machine

LESSON6NUMERICALCONTROLMACHINE--数控加工机床NCMACHINECONSTRUCTIONTherearefourcomponentsinanyNCmachine.1.TheactualNCtool.2.Themachinecontrolunit(MCU).3.ThecommunicationinterfacebetweentheNCmachineandMCU.4.AvarietyofaccessoriesforperformingspecificjobsontheNCmachine.ACTIVATORS—伺服系统TheactualNCmachinemaybeamillingmachine,lathe,drill,oranyothertypeofmachinetool.TheMCUalsohasvariousdevicesavailableforoperatorinput.InformationcontainedintheMCUiscarriedtotheactivatorsontheNCmachinethroughthecommunicationinterface.TheseactivatorsreceivetheelectronicsignalsfromtheMCUandcausethemechanicalapparatusoftheNCmachinetooperate.ACTIVATORS—伺服系统LesssophisticatedNCmachineshaveopen-loopactivators.Anopen-loopactivatorcanreceiveasignalandcarryouttheinstructionscontainedinthatsignal.ButcannotfeedbacktotheMCUtoshowthatwhethertheinstructionscarriedinthesignalhaveclosed-loopactivatorcanreceiveandcarryoutasignalandfeeddatabacktotheMCUshowingthatthesignalhasbeencarriedoutandtowhatextent.NCPROGRAMMING—数控编程TherearefourwaystoprogramanNCmachine:manualprogramming,digitizing,computerprograms,andgraphicprograms.manualprogramming手工编程Digitizing数字编程Computerprograms电脑编程Graphicprograms图表编程MANUALPROGRAMMING—手工编程Manualprogrammingisthemostcumbersomeofthefour.Itinvolvescalculatingnumericalvaluesthatidentifytoollocationandspecifytooldirection.Oncethesevalueshavebeencalculated,thenrecordedandfeedintotheMCU.DIGITIZING—数字化编程Digitizingisaprocessfrequentlyusedincomputer-aideddesignanddrafting,wherebyadrawingofapartistracedelectronically.Asitistraced,thecariouspointsonthedrawingareconvertedintoX-Ycoordinatesandstoredinthecomputer.Oncethedrawinghasbeencompletelytraced,thestoredX-YcoordinatesdefinethepartandcanbefedtoanNCmachinetoprovideinstructionsontoolpositioningandmovement.COMPUTERPROGRAM—电脑编程Writeprogramsaresimilartothosedevelopedforusewithanycomputer.Withsuchprograms,Englishlanguage-typestatementsarewrittentodescribetoolpositionsandmovement,aswellasspeedandfeedrates.SuchprogramsarefedintotheMCU,wheretheyaretranslatedintomachinelanguageandforwardedtotheNCmachine’sactivators.Themostmodern,sophisticatedmethodofprogramminganNCmachineisbyusingathree-dimensionalmodeloftheparttoprovidethedatathatguidetheNCmachineinproducingthepart.AsNCtechnologycontinuestodevelop,thisprogrammingmethodwilleventuallybeusedmorethananyother.COMPUTER-ASSISTEDNCPROGRAMMING--计算机辅助数控编程ThecomputerisbeingwidelyusedinNCprogrammingpreparing.ComputersofferoperatorsseveraladvantagesovermanuallypreparingprogrammedinstructionsforNCmachines.Ittakeslesstimetoprepareapartprogramwhileusingacomputertopreparethesameprogramautomatically.COMPUTER-ASSISTEDNCPROGRAMMING--计算机辅助数控编程Becausethecomputerperformsanynecessarycalculationsratherthanthecalculationsbeingperformedmanually,thesearefewererrorsinthefinalprogram.And,becauselesstimeisrequiredinusingacomputerandfewererrorsappearinfinalprogram,theoverallprogrammingcostsareusuallylowerwithcomputer-assistedNCprogramming.COMPUTER-ASSISTEDNCPROGRAMMING--计算机辅助数控编程WhenusingacomputertowriteanNCprogram,theoperatordescribestheoperationstobeperformedbythemachinetoolusingEnglishlanguage-likecommands.ThesecommandsaretransformedintoalanguagetheNCmachinecanunderstandbyapost-processor,aspecialcomputerprogramthatconvertsgeneralinstructionstomachine-specificinstructions.Themostwidelyusedlanguageforcomputer-assistedNCprogramming.COMPUTER-ASSISTEDNCPROGRAMMING--计算机辅助数控编程ThecomputerofferstheNCpartprogrammerthesameadvantagesandbenefitsitofferothertechnicalworkers.Byperformingcomplicatedmathematicalcalculations,itreducesthetimeinvolvedinpreparingaprogramanddecreasesthenumberoferrorsmadeinproducingaprogram.COMPUTER-ASSISTEDNCPROGRAMMING--计算机辅助数控编程Whenerrorsaremade,theyareeasiertocorrect.Itsimplifiestheinputofprogramstobestored,retrieved,andusedcontinuallywithouthavingtorerunatapeeachtimewhenamachineoperationistobeperformed.BENEFITSANDGAINSFROMNC-数控技术带来的增益Numericalcontrolhasbeeninuseforalmost40years.Sinceitsinception,ithasbeenimprovedcontinually.EachimprovementhasaddedanewbenefitorimprovedanexistingbenefitofNCascomparedwithtraditionalmanualmachineoperation.Duringthisperiod,abodyofknowledgehasdevelopedfromtheactualbenefitsthatcanbederivedfromtheNC.ThereisageneralconsensusamongmanufacturingprofessionalsthattheprincipalbenefitsderivedfromNCarethefollowing:BENEFITSANDGAINSFROMNC-数控技术带来的增益1.Betterplanning-规划更优2.Greater-flexibility-柔性更强3.Easierscheduling-进度安排更容易4.Lesssetup,lead,andprocessing-安排、引导、操作耗时更少5.Bettermachineutilization-机床利用率更高6.Loweroveralltoolingcosts-工具成本低7.Greateruniformityincutting-加工一致性好8.Greateraccuracyincutting-加工精度高BENEFITSANDGAINSFROMNC-数控技术带来的增益9.Ahigherdegreeofinterchangeabilityofpartsandtools.-刀具、部件互换性更高10.Moreaccuratecostestimates-成本预算更准确11.Permanentmemoryofhowapartwasmade-零件加工过程可永久保存BENEFITSANDGAINSFROMNC-数控技术带来的增益Thesearethesametypesofbenefitsgenerallyassociatedwithandmanufacturingprocessthathassuccessfullymovedfromamanualformattoafullyorpartiallyautomatedformat.Theextentofthebenefitdependsonhowsuccessfullythetransitionhasbeencarriedoutandhowwelldevelopedtheassoci