先进制造技术--施平三单元

1AdvancedManufacturingTechnology先进制造技术施平Part32Contents•1.IntroductiontoAMT•2.Computerandcommunication•3.Computer-aidedengineering•4.Automation•5.Modernmanufacturingtechnologies33.Computer-AidedEngineering3.4Computer-AidedManufacturing•Thefieldscomputerbeingusedinmanufacturingindustry–Financialcomputationandtransactions–Inventorymanagement–Laborreporting–Productionscheduling–Productionrouting–Numericalcontroltechnology•Applicationofcomputertechnologyinmanufacturingfieldisregardedasakeyweaponinthesocalledsecondindustrialrevolution.43.Computer-AidedEngineering•Manoperatedmachinetools–Lathe–Millingmachine–Drillingmachine–Grindingmachine•ThequalityofmachinedpartsbyManualmachinetool–arerelatedandlimitedtotheskilloftheoperator3.4.1Computer-AidedManufacturing-manualmachinetoolAmanuallathe53.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•NC(NumericalControl)–amethodofcontrollingthemovementsofmachinecomponentsbydirectlyinsertingcodedinstructionsintothesystem,thesysteminterpretsandconvertsthesedataintooutputsignals,whichcontrolvariousmachinecomponents–Toolpointpositioncontrol–Secondlyfunctionscontrol•Toolspeed•Feedrate•Coolantflow•Toolselectionandchanging•gaugingMillingcenterEXAMPLEMulti-axismachineEXAMPLEHousingboxEXAMPLE63.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•FirstNC–MIT1950,a3axesservo-controlledmillingmachinetool73.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•SometypesofCNCmachinetool–CNCmillingmachine–VMC:verticalmachiningcenter,3,4,5axesofmotion–HMC:horizontalmachiningcenter,3,4,5axesofmotion(normally,CNCmachinetoolhasanATC,orautomatictoolchanger)CNClatheVMCHMC83.Computer-AidedEngineering•TheadvantageofNC,CNCmachine–Moreaccurate–Faster–Lowercost–Higheruniformalityandconsistency–Automatic3.4.2Computer-AidedManufacturing-NC93.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•ComponentsofNCsystem–1.PartProgram•preprogrammedinstructions,tellingthemachinetoolwhattodo,stepbystep.•Certainprogramminglanguageisused•Codedonsomemedia:punchedtape;computerdisketc.(programstoredincomputer,thecomputerdirectlylinkedtothemachinetool,thisiscalleddirectnumericalcontrol,orDNC.)•DNC:directnumericalcontrol.103.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•ComponentsofNCsystem–2.CNCControlSystem•Theelectromechanicaldevice,readingandinterpretingpartprogramandconvertingitintomechanicalactionsofthemachinetool(mostmodernsystemsuseamicroprocessorasthecontrolunit,thistypeofnumericalcontroliscalledcomputernumericalcontrol,orCNC)113.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•2.CNCControlSystem–ThreesubsystemsofCNCcontrolsystem•controlunit:centerpieceofCNCsystem,(alsocalledcontrolsystem,MCU(machinecontrolunit),controller).Usually,itisacomputerandinterfaceoftheCNCsystem.•Drive:Screwandmotor–Ballscrew:eliminatingbacklashforhigh-precisionpositioning–Steppingmotor:rotatesafixedangleforaelectricalpulseinput;easytobecontrolled;discretemovement,usedinlowpricedCNCtrainerandassemblysystem–Servomotor:morecommonused,smoothandcontinuousmotion;feedbackisneeded(closedloopsystem).AlternatingcurrentservomotoristhestandardchoiceforindustrialCNCsystem•Feedback–Providesthecontrolunitwithinformationaboutthestatusofmotioncontrolsystem123.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•ComponentsofNCsystem–3.processingequipment•Itisactuallythemachinetool,whichperformthework•Componentsofprocessingequipment–Spindle–Cuttingtool–Worktable–ChunkorotherFixture–Motorsanddrivers133.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC143.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC153.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC163.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NCStepmotor&driverservomotor&driver173.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•ProgrammingofCAD–Gcode•alsocalledpreparatorycodes,andareanywordinaCNCprogramthatbeginswiththeletterG.•Generallyitisacodetellingthemachinetoolwhattypeofactiontoperform,suchas:–rapidmove–controlledfeedmoveinastraightlineorarc–seriesofcontrolledfeedmovesthatwouldresultinaholebeingbored,aworkpiececut(routed)toaspecificdimension,oradecorativeprofileshapeaddedtotheedgeofaworkpiece.–changeapallet–settoolinformationsuchasoffset.CommonFANUCGCodesforMill183.Computer-AidedEngineering3.4.2Computer-AidedManufacturing-NC•ProgrammingofCAD–Gcode•ThereareaISOstandard,butalotofNCprovidersdonotadheretoit,andtherearemanyversionseveninthesameindustry•Programmingistediousandpronetomakingmistakes•FuturedevelopmentisautomaticprogrammingwithprogramlanguagebasedoninteractivegraphicsdirectlyfromCADdatabase193.Computer-AidedEngineeringGcodeexampleToolPathforprogramLineCodeDescriptionN01M216TurnonloadmonitorN02G00X20Z20Rapidmoveawayfromthepart,toensurethestartingpositionofthetoolN03G50S2000SetMaximumspindlespeedN04M01OptionalstopN05T0303M6Selecttool#3fromthecarousel,usetooloffsetvalueslocatedinline3oftheprogramtable,indextheturrettoselectnewtoolN06G96S854M42M03M08Variable