机械外文翻译--虚拟制造在齿轮生产中的应用.doc -- 5 元

ApplicationofvirtualmanufacturingingenerationofgearsReceived29November2004/Accepted5May2005/Publishedonline24November2005SpfingerVerlag.LondonLimited2005AbstractThemanufacturingprocessofgearsisfairlycomplicatedduetothepresenceofvarioussimultaneousmotionsofthecutterandthejob.Inthispaper,anattemptismadetogeneratemeaningfuldesigndataforspurandhelicalgearsandthecorrespondingrackformcutternecessaryforthemanufacturing.Usingthisinformation,solidmodelsforthecutterandblankaredevelopedandfinallygearmanufacturingprocessesaresimulatedinavirtualmanufacturingenvironment.Theuserhastheoptiontochoosebetweendesignsandmanufacturemodeatwill.Theintegratedprocessmayalsohelptodevelopanoptimizedproduct.Forbetterunderstandingoftheoperationalprinciple,ananimationfacilityintheformofamovieisincludedinthepackage.KeywordsVirtualmanufacturingAnimationGeargeneration1IntroductionAgearisaverycommonmachineelementinmechanicalengineeringapplications.However,manufacturingofthegearseemstobefairlycomplicatedeventothepersonhavingthoroughtechnicalknowledgeintherelatedfield.Theconventionalgeargenerationprocesseslikeforming,shaping,hobbing,etc.areusuallyrepresentedintwodimensionalsketch.Theremaybesomecomponentsthatarenotadequatelydescribedbythetwodimensionalapproach.Inthecaseofgeargeneration,itmaybedifficulttounderstandthecomplexgeometriesandthemanufacturingarrangementwiththehelpof2Dmodels.Theselimitationscanbepartiallyovercomeandunderstandingwillbemoremeaningfulifoneuses3Dsolidmodelsinstead.However,thedevelopmentofthemodelsusing3Dsolidsmaynotalwaysensuretheclarityofthecomplexgeargenerationprocessunlessoneusesanimationtorepresenttilemotionofthegearblankandthegearcutter.Thiscanbeachievedveryefficientlywiththehelpofthevirtualmanufacturingtechnique.Itisatechnologytocreateavirtualenvironmentonthecomputerscreentosimulatethephysicalworld.Theknowledgebaseandexpertisegainedfromtheworkinthevirtualenvironmentenablestheusertoapplythemmoremeaningfullyinreallifesituations.Ahostofliteratureisavailableonvirtualmanufacturingindifferentareasamongwhichsomeoftherecentandimportantworksarereferredbelow.TesicandBaneljee1haveworkedintheareaofrapidprototyping,whichisanewtechnologyfordesign,visualizationandverification.Graphicaluserinterfaces,virtualrealitytechnologies,distillation,segregationandautointerpretationaresomeoftheimportantfeaturesoftheirwork.Balylissetal.2dealtwiththedevelopmentofmodelsinavirtualenvironmentusingthevirtualrealitytechnologiesprovidinganoutstanding3Dvisualizationoftheobject.In1994,G.M.Balylissetal.3presentedtheoreticsolidmodelingtechniquesusingtheVMtools,likeVP,MI,virtualrealitymanufacturinglanguageand3DSludioMax.Theyhavedevelopeddifferentpartsofanautomobileandthroughthespecialeffectofanimationimpartedallpossiblemotiontothemodel.ThetechnologyisfurtherenhancedbyKiulera4,whotreatedproductandprocessmodelingasakernelforthevirtualmanufacturingenvironment.Inhiswork,Kimurahasincorporatedsignificantmodelingissueslikerepresentation,representationlanguage,abstraction,standardization,configurationcontrol,etc.ArangarasauandGadh5contributedtowardsthevirtualprototypingthatareconstructedusingsimulationoftheplannedproductionprocessusingvirtualmanufacturingonaplatformofMAYA,3DStudioMaxandVRML,etc.At.JadavpurUniversity,researchwork6,7isbeingcarriedouttosimulatethegearmanufacturingprocessesusingAIIllCADand31StudioMaxasplatforms.Softwarehasbeendevelopedthathelpsthedesignengineerstounderstandtheproblemsrelatedtospurgearoperationanditsmanufacturingprocess.Astudyofthestateoftileartandliteraturereviewrevealthatthescopeofvirtualmanufacturingiswideopenforsimulatingspurgeargenerationprocesses.Computersimulationcanbeveryeffectivelyusedforviewingalongwithaidingsubsequentanalysisofdifferentcomplicatedmanufacturingprocessesusingtheconceptofdesigncenteredvirtualmanufacturing.Withthisobjectiveinmind,anattemptismadetovirtuallymanufacturespurandhelicalgearsfromtheblankusingarackcutter.Thescopeoftheworkincludesthegenerationofdesigndataforthespurandhelicalgearsandtherackformcutter,thegenerationofsolidmodelsforthecutterandblank,andfinallytosimulategearmanufacturingprocessthroughanimation.Themainmotivationoftheworkistosimplifythetaskofdesigning,andtostudythegeargenerationprocessthatcanbeunderstoodbyalaymanandtopresentarealisticviewofit.Alltheprocessesaredevelopedontheplatformofthe3DStudioMax,whichisoneofthemostimportantvirtualtools.Thesoftwareisdevelopedusingmaxscript,anobjectcontainedprogramminglanguagethatcanberunin3DStudioMaxenvironment.2DescriptionofthesoftwareThemaxscriptlanguageisbasicallyanimageprocessorthatcreatesthevisualeffectsin3DStudioMax.Inaddition,itcanbeusedfordesigncalculationandsubsequentchecking.Anattemptismadetodeveloptheentirepackageinmodularformsothatanyfurtherimprovementcanbeimplementedeasilywithoutaffectingtheothers.Theentireworkiscarriedoutina3Denvironment.ThemodularstructureoftheentirepackageispresentedinFig.l.Themajormodulesareinputmodule,geardesignmodule,virtualmanufacturingmoduleandspecialmodule.Abriefdescriptionofthesemodulesismentionedbelow.2.1InputmoduleThismoduleisdevelopedtoprovideinputparametersthatareessentialfortiedesignanddevelopmentofthespurandhelicalgearsandthecorrespondingcutters.Inordertomakethesoftwareuserfriendly,theprocessofinputtingthedataisspecificallydonethroughaninputdialogueboxcreatedbythemaxscriptlanguage.AsampledialogueboxisshowninFig.2.Somefieldshavesomerestrictionslikepredefinedlowerorupperlimitsorpredefinedstepsforincrementordecrement.Thisisdonepurposivelytomaketheenvironmentmoreuserfriendlyandtorestricttheuserfromenteringinvaliddata,forexample,ausercannotmakethenumberofgearteethlessthan18.2.2GeardesignmoduleBeforegoingforthegenerationofthegears,oneshouldevaluatethevariousdesignparametersofthegearstobemanufacturedbasedontheinputparameters.Inordertodesignagearpair,thefollowingdataareessential.IRpmatwhichthegearisrunning2.Thepowerbeingtransmitted3.ThetransmissionratiooftheassemblyInaddition,usersmayspecifythefollowingoperationalconditions/parameters1.Precisionofthegearassembly2.Pressureangleofthegear3.Materialofthepinion4.Typeofshockloadrequiredforthepiniontotakeup5.HelixangleincaseofhelicalgearIftheuserisnotsatisfiedwiththeoutput,hecanmodifytheinputtoobtaindesiredoutput.Inthismodule,theentiredesignprocedureforthegearshasbeentreated.Thedifferentaspectsofdesigncalculations,forexample,dynamicload,staticloadfatigueloadandthewearloadhavebeencalculatedinseparateprograms,andaredisplayedthroughtheoutputdialogbox.Whiledesigningthegear,ithasbeenkeptinmindthatthegearhastoformmeshwiththatoftherack,socarehasbeentakentoavoidtheinterferenceofthematingpair.2.2.1MethodologyVarietiesofgearcuttingprocessesareavailableandaregenerallybeingfollowedintheindustriesduringtheirmanufacturing.Inthispaper,Focusisgivenongearmanufacturingthroughgeneration.Theunderlyingprincipleofgeardesignisbasedonthefactthattheprofilesofapairofgearteethbearadefiniterelationshiptoeachothersuchthatthepairofteethhaveapredeterminedrelativemotionandcontactateveryinstant.Therefore,iftherelativemotionoftheprofilesandtheformofoneofthemisknown,thedeterminationoftheformoftheothermayberegardedastileproblemcapableofsolutionbyeithergraphicaloranalyticalmeans.Theactualproductionofgeartoothrepresentsasolutiontotheaboveproblembymechanicalmeansknownasgeneration.Thegenerationisamethodthatfollowsthefollowingprinciples.1.Acuttingedgebasicallyagearwithcuttingedgesisgivenamotion.Asaresult,itiscausedtosweepoutthesurfacecorrespondingtotheactualteethsurfacesoftheknownmemberofapairofconjugategears.2.Ablankismountedatanappropriaterelationshiptothecutter.Itisgivenamotionthatthefinishedgearmusthaverelativetothatofthecutter.Asaresultofthesimultaneousmovementandthecuttingactionofthecutter,teethareformedontheblankconjugatetothatrepresentedbythecutter.Infactduetotheadditionoftherelativemotion,theprofilegiventotheworkpieceisdifferentfromthatofthecutter.Thisdifferentiatesthegeneratingfromtheformingoperation.2.2.2SpurgearGenerationofspurgearbymeansofcuttercorrespondinginformtothematinggeariswellknown.Cuttermaybeintheformofarack.Foraninvolutesystemoftoothprofiles,thecuttercorrespondingtotherackwillhavestraightsides.ThearrangementofsuchacutterrelativetotheblankisshowninFig.3.Thecutterisadjustedradiallywithrespecttotheaxisofthework.Itisreciprocatedsothatitsedgesmaysweepoutthesurfaceoftheteethoftheimaginaryrackformingthebasisofthedesignofthetoothprofileoftheblank.Inadditiontothisreciprocation,thecutterisadvancedinthedirectionofthepitchlineandatthesametimetheworkisrotatedaboutitsaxisataspeedsuchthatitispitchpointhasthesamelinearvelocityasthatoftherack.Inotherwords,thepitchcircleoftheblankandthepitchlineoftherackrolltogether.Inconsequencethestraightcuttingsedgesgeneratetheinvoluteprofileintheblank.Forsuchaprocesstobecontinuous,Thelengthofthecuttershouldbesomewhatlongerthanthepitchcircumferenceoftheworksincethisisusuallyimpracticable．Thecutteriswithdrawnfromtheworkafterithasadvancedadistanceequaltoallintegralnumberofpitchesandreturntoitsstartingpoint，theblankinthemeantimeremainsstationary．Thisisrepeateduntilalltheteetharecut．2.2.3HelicalgearItiswellknownthatahelicalinvolutegearisconjugatetoastraightrackhavinginclinedteeth．Therefore，thesamemethoddescribedabovecanbeemployedtomanufactureahelicalgear．However,thedirectionofreciprocationoftherackcuttermustbeinclinedtotheaxisoftheblankatallangleequaltothehelixangleofthegear．Thecuttermustrollovertheblankinadirectionsimilartothatdescribedearlier．Thesimultaneousmotioninvolvedandtheorientationof