机械设计制造及自动化毕业设计英文翻译资料Word文档下载推荐.docx

机械设计制造及自动化毕业设计英文翻译资料Word文档下载推荐.docx

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Thispaperpresentsanovelintegratedsystemofrapidproductdevelopmentforreducingthetimeandcostofproductdevelopment.Thesystemiscomposedoffourbuildingblocks—digitalprototype,virtualprototype,physicalprototypeandrapidtoolingmanufacturingsystem.Itcanaideffectivelyinproductdesign,analysis,prototype,mould,andmanufacturingprocessdevelopmentbyintegratingcloselythevariousadvancedmanufacturingtechnologieswhichinvolvethe3DCAD,CAE,reverseengineering,rapidprototypingandrapidtooling.Furthermore,twoactualexamplesareprovidedtoillustratetheapplicationofthisintegratedsystem.Theresultsindicatethatthesystemhasahighpotentialtoreducefurtherthecycleandcostofproductdevelopment.

Keywords:

Rapidproductdevelopment;

rapidprototyping;

integratedsystem.

1.Introduction

Duetothepressureofinternationalcompetitionandmarketglobalizationinthe21stcentury,therecontinuestobestrongdrivingforcesinindustrytocompeteeffectivelybyreducingmanufacturingtimesandcostswhileassuringhighqualityproductsandservices.Currentindustriesarefacingthenewchallenges:

quickresponsetobusinessopportunityhasbeenconsideredasoneofthemostimportantfactorstoensurecompanycompetitiveness;

manufacturingindustryisevolvingtowarddigitalization,networkandglobalization.Therefore,newproductsmustbemorequicklyandcheaplydeveloped,manufacturedandintroducedtothemarket.Inordertomeetthedemandofrapidproductdevelopment,thevariousnewtechnologiessuchasreverseengineering（RE）,3DCAD,rapidprototyping（RP）,andrapidtooling（RT）haveemergedandareregardedaskeyenablingtoolswiththeabilitytoshortentheproductdevelopmentandmanufacturingtime.Forexample,ithasbeenclaimedthatRPcancutnewproductdevelopmentcostsbyupto70%andthetimetomarketby90%.1Intheformofabetterdesign,moredesignpossibilities,a3DCADmodelcanbeshowntothecustomerforapprovalandpreventsmisunderstandings.Avirtualprototypingisemployedtoguideinoptimizationoftheproductdesignandmanufacturingprocessplanning,whichmayresultintheaccuratedeterminationoftheprocessparameters,andreducethenumberofcostlyphysicalprototypeiterations.Rapidtoolingtechniqueoffersafastandlowcostmethodtoproducemoulds,andshowsahighpotentialforfasterresponsetomarketdemands.Whenproperlyintegratedamong3DCAD,CAE,RE,RPandRT,thesetechnologieswillplayamuchmoreimportantroletoreducefurtherthedevelopmentcycleandcostoftheproductproduction.Onthebasisofabovetechnologies,anovelintegratedsystemofrapidproductdevelopmentistobefoundedsoastomeettherequirementofrapidproductdevelopment.

2.ArchitectureoftheIntegratedDevelopmentSystem

Thedevelopmentprocessfrominitialconceptualdesigntocommercialproductisaniterativeprocesswhichincludes:

productdesign;

analysisofperformance,safetyandreliability;

productprototypingforexperimentalevaluation;

anddesignmodification.Therefore,anystepofthenewproductdevelopmentprocesshasadirectandstronginfluenceontime-to-marketinshortorder.Agoodproductdevelopmentsystemmustenabledesignersordesignteamstoconsiderallaspectsofproductdesign,manufacturing,sellingandrecyclingattheearlystageofthedesigncycle.Sothatdesigniterationandchangescanbemadeeasilyandeffectively.Themorefluentthefeedbackisthehigherpossibilityofsuccessthesystemhas.Designformanufacturing（DFM）andconcurrentengineering（CE）necessitatethatproductandprocessdesignbedevelopedsimultaneouslyratherthansequentially.

Theintegratedsystemofrapidproductdevelopmentiscomposedoffourmodules:

digitalprototype,virtualprototype,physicalprototypeandrapidtooling.Theproductdevelopmentstartsfromthecreationofa3DCADmodelusingaCADsoftwarepackage.Atthatstage,theproductgeometryisdefinedanditsaestheticanddimensionalcharacteristicsareverified.Themainfunctionofdigitalprototypeistoperform3DCADmodelling.TheCADmodelisregardedasacentralcomponentofthewholesystemorprojectinformationbasewhichmeansthatinalldesign,analysisandmanufacturingactivitiesthesamedataisutilized.Theproductanditscomponentsaredirectlydesignedona3DCADsystem（e.g.Pro/Engineer,Unigraphics,CATIA,IDEAS,etc.）duringthecreativedesign.Ifaphysicalpartisready,themodelcanbeconstructedbythereverseengineeringtechnique.REisamethodologyforconstructingCADmodelsofphysicalpartsbydigitizinganexistingpart,creatingadigitalmodelandthenusingittomanufacturecomponents.REcanreducethedevelopmentcyclewhenredesignsbecomenecessaryforimprovedproductquality.Preexistingpartswithfeaturesforimprovedperformancecanbereadilyincorporatedintothedesiredpartdesign.Therefore,itisveryusefulincreatingtheCADmodelofanexistingpartwhentheengineeringdesignislostorhasgonethroughmanydesignchanges.Whenadesignercreatesanewdesignusingmock-up,itisalsonecessarytoconstructtheCADmodelofthemock-upforfurtheruseofthedesigndatainanalysisandmanufacturing.ThethreeprimarystepsinREprocessarepartdigitization,featuresextraction,andCADmodelling.Partdigitizationisaccomplishedbyavarietyofcontactornon-contactdigitizers.Therearevariouscommercialsystemsavailableforpartdigitization.Thesesystemsrangefromcoordinatemeasuringmachine（CMM）,laserscannerstoultrasonicdigitizers.Theycanbeclassifiedintotwobroadcategories:

contactandnon-contact.Lasertriangulationscanner（LTS）,magneticresonanceimages（MRI）,andcomputertomography（CT）arecommonlyusedasnon-contactdevices.ContactdigitizersmainlyhaveCMMandcross-sectionalimagingmeasurement（CIM）.Featureextractionisnormallyachievedbysegmentingthedigitizeddataandcapturingsurfacefeaturessuchasedges.Partmodellingisfulfiledthroughfittingavarietyofsurfacestothesegmenteddatapoints.

Inordertoreducetheiterationsofdesign-prototype-testcycles,increasetheproductprocessandmanufacturingreliability,itisnecessarytoguideinoptimizingtheproductdesignandmanufacturingprocessthroughvirtualprototype（VP）.VPisaprocessofusing3DCADmodel,inlieuofaphysicalprototype,fortestingandevaluationofspecificcharacteristicsofaproductoramanufacturingprocess.ItisoftencarriedoutbyCAEandvirtualmanufacturingsystem.Computeraidedengineering（CAE）analysisisanintegralpartoftime-compressiontechnologies.Varioussoftwaretoolsavailable（i.e.ANSYS,MARC,I-DEAS,AUTOFORM,DYNAFORM,etc.）canspeedupthedevelopmentofnewproductsbyinitiatingdesignoptimizationbeforephysicalprototypesarebuilt.TheCADmodelscanbetransferredtoaCAEenvironmentforananalysisoftheproductfunctionalperformanceandofthemanufacturingprocessesforproducingtheproduct’scomponents.Ithasalsoproventobeofgreatvalueinthedesignoptimizationofpartgeometry,todetermineitsdimensionsandtocontrolwarpageandshrinkagewhileminimizingprocess-inducedresidualstressesanddeformations.Virtualmanufacturingsystem（VM）isthenaturalextensionofCAE.Itsimulatestheproductfunctionalityandtheprocessesforproducingitpriortothedevelopmentofphysicalprototypes.VMenablesadesignertovisualizeandoptimizeaproductprocesswithasetofprocessparameters.Thevisualizationofavirtuallysimulatedpartpriortophysicalfabricationhelpstoreduceunwantedprototypeiterations.Therefore,aproductvirtualmanufacturingsystemmayresultinaccuratedeterminationoftheprocessparameters,andreducethenumberofcostlyphysicalprototypeiterations.3DCADmodelandVPallowmostproblemswithunfittingtobecomeobviousearlyintheproductdevelopmentprocess.AssembliescanbeverifiedforinterferenceasVPcanbeexercisedthrougharangeoftasks.StructureandthermalanalysiscanbeperformedonthesamemodelemployingCAEapplicationsaswellassimulatingdown-streammanufacturingprocesses.ItisclearthatVPincreasesprocessandproductreliability.AlthoughVPisintendedtoensurethatunsuitabledesignsarerejectedormodified,inmanycases,avisualandphysicalevaluationoftherealcomponentisneeded.Thisoftenrequiresphysicalprototypetobeproduced.Hence,oncetheVPisfinished,themodelmayoftenbesentdirectlytophysicalfabrication.

TheCADmodelcanbedirectlyconvertedtothephysicalprototypeusingaRPtechniqueorhigh-speedmachining（HSM）process.The3DCADmodelistobeexportednotonlyintheSTLformatwhichisconsideredthedefactostandardforinterfacingCADandRPsystems,butalsointheNCcodingwhichcanbeusedbyHSM.HSMhasapotentialforrapidproducingplasterorwoodenpatternforRT.RPisanewformingprocesswhichfabricatesphysicalpartslayerbylayerundercomputercontroldirectlyfrom3DCADmodelsinaveryshorttime.Incontrasttotraditionalmachiningmethods,themajorityofrapidprototypingsystemstendtofabricatepartsbasedonadditivemanufacturingprocess,ratherthansubtractionorremovalofmaterial.Therefore,thistypeoffabricationisunconstrainedbythelimitationsattributedtoconventionalmachiningapproaches.TheapplicationofRPtechniqueasausefultoolcanprovidebenefitsthroughouttheprocessofdevelopingnewproducts.Specifically,thereareseriousbenefitsthatRPcanbringintheareasofmarketresearch,salessupport,promotionalmaterial,andtheever-importantproductlaunch.PhysicalRPcanals