ApplicationofvirtualmanufacturingingenerationofgearsReceived:29November2004/Accepted:5May2005/Publishedonline:24November2005Spfinger-Verlag.LondonLimited2005AbstractThemanufacturingprocessofgearsisfairlycomplicatedduetothepresenceofvarioussimultaneousmotionsofthecutterandthejob.Inthispaper,anattemptismadetogeneratemeaningfuldesigndataforspurandhelicalgearsandthecorrespondingrackformcutternecessaryforthemanufacturing.Usingthisinformation,solidmodelsforthecutterandblankaredevelopedandfinallygear-manufacturingprocessesaresimulatedinavirtualmanufacturingenvironment.Theuserhastheoptiontochoosebetweendesignsandmanufacturemodeatwill.Theintegratedprocessmayalsohelptodevelopanoptimizedproduct.Forbetterunderstandingoftheoperationalprinciple,ananimationfacilityintheformofamovieisincludedinthepackage.KeywordsVirtualmanufacturing；Animation；Geargeneration1IntroductionAgearisaverycommonmachineelementinmechanicalengineeringapplications.However,manufacturingofthegearseemstobefairlycomplicatedeventothepersonhavingthoroughtechnicalknowledgeintherelatedfield.Theconventionalgeargenerationprocesseslikeforming,shaping,hobbing,etc.areusuallyrepresentedintwo-dimensionalsketch.Theremaybesomecomponentsthatarenotadequatelydescribedbythetwo-dimensionalapproach.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,(virtualrealitymanufacturinglanguage)and3DSludioMax.Theyhavedevelopeddifferentpartsofanautomobileandthroughthespecialeffectofanimationimpartedallpossiblemotiontothemodel.ThetechnologyisfurtherenhancedbyKiulera4,whotreatedproductandprocessmodelingasakernelforthevirtualmanufacturingenvironment.Inhiswork,Kimurahasincorporatedsignificantmodelingissueslikerepresentation,representationlanguage,abstraction,standardization,configurationcontrol,etc.ArangarasauandGadh5contributedtowardsthevirtualprototypingthatareconstructedusingsimulationoftheplannedproductionprocessusingvirtualmanufacturingonaplatformofMAYA,3DStudioMaxandVRML,etc.At.JadavpurUniversity,researchwork6,7isbeingcarriedouttosimulatethegearmanufacturingprocessesusingAIIll)CADand31)StudioMaxasplatforms.Softwarehasbeendevelopedthathelpsthedesignengineerstounderstandtheproblemsrelatedtospurgearoperationanditsmanufacturingprocess.Astudyofthestateoftileartandliteraturereviewrevealthatthescopeofvirtualmanufacturingiswideopenforsimulatingspurgeargenerationprocesses.Computersimulationcanbeveryeffectivelyusedforviewingalongwithaidingsubsequentanalysisofdifferentcomplicatedmanufacturingprocessesusingtheconceptofdesigncenteredvirtualmanufacturing.Withthisobjectiveinmind,anattemptismadetovirtuallymanufacturespurandhelicalgearsfromtheblankusingarackcutter.Thescopeoftheworkincludesthegenerationofdesigndataforthespurandhelicalgearsandtherackformcutter,thegenerationofsolidmodelsforthecutterandblank,andfinallytosimulategear-manufacturingprocessthroughanimation.Themainmotivationoftheworkistosimplifythetaskofdesigning,andtostudythegeargenerationprocessthatcanbeunderstoodbyalaymanandtopresentarealisticviewofit.Alltheprocessesaredevelopedontheplatformofthe3DStudioMax,whichisoneofthemostimportantvirtualtools.Thesoftwareisdevelopedusingmax-script,anobjectcontainedprogramminglanguagethatcanberunin3DStudioMaxenvironment.2DescriptionofthesoftwareThemax-scriptlanguageisbasicallyanimageprocessorthatcreatesthevisualeffectsin3DStudioMax.Inaddition,itcanbeusedfordesigncalculationandsubsequentchecking.Anattemptismadetodeveloptheentirepackageinmodularformsothatanyfurtherimprovementcanbeimplementedeasilywithoutaffectingtheothers.Theentireworkiscarriedoutina3Denvironment.ThemodularstructureoftheentirepackageispresentedinFig.l.Themajormodulesare:inputmodule,geardesignmodule,virtualmanufacturingmoduleandspecialmodule.Abriefdescriptionofthesemodulesismentionedbelow.2.1InputmoduleThismoduleisdevelopedtoprovideinputparametersthatareessentialfor(tiedesignanddevelopmentofthespurandhelicalgearsandthecorrespondingcutters.Inordertomakethesoftwareuserfriendly,theprocessofinputtingthedataisspecificallydonethroughaninputdialogue-boxcreatedbythemax-script-language.AsampledialogueboxisshowninFig.2.Somefieldshavesomerestrictionslikepredefinedlowerorupperlimitsorpredefinedstepsforincrementordecrement.Thisisdonepurposivelytomaketheenvironmentmoreuserfriendlyandtorestricttheuserfromenteringinvaliddata,forexample,ausercannotmakethenumberofgearteethlessthan18.2.2Gear-designmoduleBeforegoingforthegenerationofthegears,oneshouldevaluatethevariousdesignparametersofthegearstobemanufacturedbasedontheinputparameters.Inordertodesignagearpair,thefollowingdataareessential.IRpmatwhichthegearisrunning2.Thepowerbeingtransmitted3.ThetransmissionratiooftheassemblyInaddition,usersmayspecifythefollowingoperationalconditions/parameters:1.Precisionofthegearassembly2.Pressureangleofthegear3.Materialofthepinion4.Typeofshockloadrequiredforthepiniontotakeup5.HelixangleincaseofhelicalgearIftheuserisnotsatisfiedwiththeoutput,hecanmodifytheinputtoobtaindesiredoutput.Inthismodule,theentiredesignprocedureforthegearshasbeentreated.Thedifferentaspectsofdesigncalculations,forexample,dynamicload,staticload(fatigueload)andthewearloadhavebeencalculatedinseparateprograms,andaredisplayedthroughtheoutputdialogbox.Whiledesigningthegear,ithasbeenkeptinmindthatthegearhastoformmeshwiththatoftherack,socarehasbeentakentoavoidtheinterferenceofthematingpair.2.2.1MethodologyVarietiesofgearcuttingprocessesareavailableandaregenerallybeingfollowedintheindustriesduringtheirmanufacturing.Inthispaper,Focusisgivenongearmanufacturingthroughgeneration.Theunderlyingprincipleofgeardesignisbasedonthefactthattheprofilesofapairofgearteethbearadefiniterelationshiptoeachothersuchthatthepairofteethhaveapredeterminedrelativemotionandcontactateveryinstant.Therefore,iftherelativemotionoftheprofilesandtheformofoneofthemisknown,thedeterminationoftheformoftheothermayberegardedastileproblemcapableofsolutionbyeithergraphicaloranalyticalmeans.Theactualproductionofgeartoothrepresentsasolutiontotheaboveproblembymechanicalmeansknownasgeneration.Thegenerationisamethodthatfollowsthefollowingprinciples.1.Acuttingedge(basicallyagearwithcuttingedges)isgivenamotion.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,Thelengthofthecuttershouldbesomewhatlongerthanthepitchcircumferenceofthework；sincethisisusuallyimpracticableThecutteriswithdrawnfromtheworkafterithasadvancedadistanceequaltoallintegralnumberofpitchesandreturntoitsstartingpoint，theblankinthemeantimeremainsstationaryThisisrepeateduntilalltheteetharecut2.2.3HelicalgearItiswellknownthatahelicalinvolutegearisconjugatetoastraightrackhavinginclinedteethTherefore，thesamemethoddescribedabovecanbeemployedtomanufactureahelicalgearHowever,thedirectionofreciprocationoftherackcuttermustbeinclinedtotheaxisoftheblankatallangleequaltothehelixangleofthegearThecuttermustrollovertheblankinadirectionsimilartothatdescribedearlierThesimultaneousmotioninvolvedandtheorientationof