机械制造类专业英语（第2版）课件 module three advanced manufacturing design and cases

ModuleIIIadvancedmanufacturingdesignandcasesAcomputernumericalcontrol(CNC)machineisanNCmachinewiththeaddedfeatureofanon-boardcomputer.Theon-boardcomputerisoftenreferredtoasthemachinecontrolunitorMCU.TheMCUusuallyhasanalphanumerickeyboardfordirectormanualdatainput(MDI)ofpartprograms

▲continuous-path(orcontouring)toolmovements▲incrementalpositioning▲closed-loop▲right-handcoordinatesystem▲left-handcoordinatesystem.▲Hydraulic▲pneumatic▲electric▲point-to-pointtoolmovements▲absolutepositioning▲open-loopMachiningcentresarethedevelopmentinCNCtechnology.Turningcenterswithincreasedcapacitytoolchangersarealsomakingstrongappearanceinmodernproductionshops.TheseCNCmachinesarecapableofexecutingmanydifferenttypesoflathecuttingoperationssimultaneouslyonrotatingpart.Inadditiontomachiningcentersandturningcentres,CNCtechnologyhasalsobeenappliedtomanyothertypesofmanufacturingequipment.Amongthesearewireelectricaldischargemachines(WEDM)andlasercuttingmachines.SessionOneCNCprogrammingAclosed-loopsystem-Aclosed-loopsystemutilizestheservemotorwhosetypesincludeACservomotorisedservomotors.（）Anopen-loopsystem-Anopen-loopsystemutilizessteppingmotorstocreatemachinemovements.Canyoumakeclearthemeaningofthefollowingfigures?Surveyyourworkplacecarefullywithyourteammatesandtrytogiveeachofthemacorrespondinganswerfromtheanswersheetfollowingthefigures.（）machineaxisforathree-axisverticalCNCmachine（machineaxisdefinedasspindlemovement）（）machineaxisforathree-axishorizontalCNCmachine（machineaxisdefinedasspindlemovement）（）coordinatesystemforahorizontalmillingmachine（）coordinatesystemforaverticalmillingmachine（）machineaxesforsix-axisverticalCNCmachine（）thewordsspecifywhichunits,whichinterpolator,absoluteorincrementalprogramming,whichcircularinterpolationplane,cuttercompensation,andsoon.（）definethreedimensional(andthreerotational)axes.（）specifyfeedandspeed.（）specifiestooldiameter,nexttoolnumber,toolchange,andsoon.（）specifydrillcycle,borncycle,millcycle,andclearanceplane.（）specifythecoolantcondition,thatis,coolanton/off,flood,andmist.（）Point-to-pointtoolmovementscausethetooltoapointonthepartandexecuteanoperationatthatpointonly.（）Continuous-pathtoolmovementsaresonamedbecausetheycausethetooltomaintaincontinuouscontactwiththepartasthetoolcutsacontourshape.16.CONTROLPANEL17.POWERON/OFF18.RESET5.MDI6.HANDLE7.JOG8.CYCLESTART14.RAPIDTRAVERSEOVERRIDE15.MACHINELOCK9FEEDHOLD10SINGLEBLOCK11.dryrun19.CRTCHARACTERDISPLAY20.DISPLAY1.EMERGENCYSTOP2.MODESELECT3.EDIT4.MEMORY12REFERENCERETUR13.FEEDRATEOVERRIDE（）Thecontentsofthecurrentlyactiveprogramareactivesequencenumberdisplay（）Thescreenisonwhichallthecharacters(addresses)anddataareshown（）Thisbuttonisusedforalarmingcancellationorcancellationofanoperation.（）Thecontrolisalwaysturnedonafterthemainpowerswitch,locatedonthedoorofthecontrolsystem（）Usually,thecontrolpanelislocatedatthefrontofthemainelectronicsystemandisequippedwithascreenandwithvariousbuttonsandswitches（）Thisswitchisusedtocheckanewprogramonthemachine.Allmovementsofthetoolareblocked,whileacheckisrunonthecomputerscreen.（）thismodeenablestheautomaticcontrolofthemachine.（）thismodeenablestheNCtocommandthememorytobeexecuted.（）thismodeenablesyouto:Entertheprogramtomachinememory,Enteranychangestotheprogram,Transferdatafromtheprogramtoatape,Checkthememorystoragecapacity.（）Usethisswitchtospecifytheoperationalmod.（）thisbuttonisredandislocatedinthelowerleftcornerofthecontrolpanel.InaCNCsystem,each_____________ofmotionisequippedwithaseparatedrivingsourcethatreplacesthehandwheeloftheconventionalmachine.Thedrivingsourcecanbe___________motor,a_______________,ora__________________.Thesourceselectedis______________mainlybasedontheprecisionrequirementsObserveyourworkplacewithyourcolleaguesthedifferentkindsoflathesalsothecomponentsofaCNClatheandthentryyourbesttofinishoffthefollowingtasks:task1,fillintheblanksinthefollowingfigures;task2,rememberthemwiththehelpofyourgroupmembers,thendictatethemforeachother.

ComponentsofaCNClathehorizontalmachiningcenter加工中心turningcenter立式加工中心millingmachine电火花加工机床machiningcenter车削中心verticalmachiningcenter铣床CNCmachiningcenter数控加工中心coordinatesystem坐标系electro-dischargemachine卧式加工中心Manytoolpathsaresimplytoodifficultandexpensivetoprogrammanually.Forthesesituations,weneedthehelpofacomputertowriteanNCpartprogram.ThefundamentalconceptofCAD/CAMidthatwecanuseaCADdraftingsystemtodrawthegeometryofawokpieceonacomputer.Oncethegeometryiscompleted,thenwecanuseaCAMsystemtogenerateanNCtoolpathbasedontheCADgeometry

themodelisverified.theCAMsystemcreatestoolpaths.thegeometryisdefinedintheCADdrawingWorkinyourworkplaceandobservetheCAD/CAMsystemcarefullyandthentrytofillintheblanksinthefollowingfigures

WatchtheCADdrawingcarefullyinyourworkplaceanddiscussitwithyourgroupmembersthefourstepsfromaCADdrawingtotheworkingNCcodethenputthefollowingsentencesinrightorderwiththehelpofyourteammates.()ThefinalproductofCAD/CAMprocessistheNCcode.()ThegeometryisdefinedinaCADdrawing.()ThemodelisnestimportedintotheCAMmodule.()TheCAMmodelisthenverifiedtoensurethatthetoolpathsarecorrect.CAD/CAMsystemscontainbothCADandCAMcapabilities,eachofwhichhasanumberoffunctionalelements.TheCADportionofthesystemisusedtocreatethegeometryasaCADmodel.TheCADsystem,whetherstandaloneoraspartofaCAD/CAMpackage,tendstobeavailableinseveraldifferentlevelsofsophistication.Wireframescanbedifficulttovisualize,butallZ-axisinformationisavailablefortheCAMoperations.Solidmodelscanbeslicedopentorevealinternalfeaturesandnotjustathinskin.A.theCAMmoduleisusedtocreatethemachiningprocessmodelbaseduponthegeometrysuppliedintheCADmodel.B.theCAMsystemwillgenerateagenericintermediatecodethatdescribesthemachiningoperation,whichcanlaterbeusedtoproduceGandMcodeorconversationalprograms.C.theCAMmodulesalsocomeinseveralclassesandlevelsofsophistication.（）CAM模块也有多种类型和层次。（）CAM系统生成描述加工操作的普通中间代码，这些代码以后可以用来生成G和M代码或会话式程序。（）根据CAD模型提供的几何形状，CAM模块用于创建加工工艺模型。WeknowastandardCNCmachinetoolcan’tbeusedtodirectlyproduceanellipse.Howdowesolvethisproblem?Readthefollowingmaterialsandobservethefiguresfollowingthematerialsandthentrytofindouttheanswers.TheCAMsystemwillreconcilethisproblembyestimatingthecurvewithlinesegments.TheCAMsystemwillgenerateaboundinggeometryoneithersideofthetruecurvetoformatolerancezone.Smallertolerancezoneswillproducefinertoolpathsandmorenumerouslinesegments,whilelargertolerancezoneswillproducefewerlinesegmentsandcoarsertoolpaths.1.OneimportantconceptwemustunderstandisthatthegeometryrepresentedbytheCADdrawingmaynotbeexactlythesamegeometrythatisproducedontheCNCmachinetool.

2.Tocreatethemachiningoperations,theCAMsystemwillneedtoknowwhichcuttingtoolsareavailableandwhatmaterialwearemachining.

3.Itiseasytorelyonthecomputertogeneratethecorrecttoolpath,butfinishedsurfacesarefurtherestimatedduringmachiningwithballendmills.

PureCADsystemsareusedinallareasofdesign,andvirtuallyanyproducttodayisdesignedwithCADsoftware.Gonearethedaysofpencilandpaperdrawings.ThismismatchsetsuptheclassicargumentbetweentheCADdesignersandtheCAD/CAMprogrammeronwhatisthebestwaytoapproachCAD/CAM.Thegreatertheacceptanceofthestandard,thegreaterthereturnoninvestmentforthebusinessesthatownthesoftware.Regardlessofthepaththatischosen,organizationsandindividualstendtobecomeentrenchedinparticulartechnology.Fillintheblankinthefollowingpassagethentalkaboutit.Operatingsystemsareprograms__________foraspecificcomputerorclassofcomputers.Forconvenientandefficientoperation,__________anddataareavailableinthesystem’smemory.Theoperating__________isespeciallyconcernedwiththeinput/output(I/O)deviceslike__________