機械制造類專業(yè)英語（第2版）課件 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電火花加工機床machiningcenter車削中心verticalmachiningcenter銑床CNCmachiningcenter數(shù)控加工中心coordinatesystem坐標系electro-dischargemachine臥式加工中心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模塊也有多種類型和層次。（）CAM系統(tǒng)生成描述加工操作的普通中間代碼，這些代碼以后可以用來生成G和M代碼或會話式程序。（）根據(jù)CAD模型提供的幾何形狀，CAM模塊用于創(chuàng)建加工工藝模型。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__________