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1、ApplicationofvirtualmanufacturingingenerationofgearsReceived:29November2004/Accepted:5May2005/Publishedonline:24November2005Spfinger-Verlag.LondonLimited2005AbstractThemanufacturingprocessofgearsisfairlycomplicatedduetothepresenceofvarioussimultaneousmotionsofthecutterandthejob.Inthispaper,anattempt

2、ismadetogeneratemeaningfuldesigndataforspurandhelicalgearsandthecorrespondingrackformcutternecessaryforthemanufacturing.Usingthisinformation,solidmodelsforthecutterandblankaredevelopedandfinallygear-manufacturingprocessesaresimulatedinavirtualmanufacturingenvironment.Theuserhastheoptiontochoosebetwe

3、endesignsandmanufacturemodeatwill.Theintegratedprocessmayalsohelptodevelopanoptimizedproduct.Forbetterunderstandingoftheoperationalprinciple,ananimationfacilityintheformofamovieisincludedinthepackage.KeywordsVirtualmanufacturing；Animation；Geargeneration1IntroductionAgearisaverycommonmachineelementin

4、mechanicalengineeringapplications.However,manufacturingofthegearseemstobefairlycomplicatedeventothepersonhavingthoroughtechnicalknowledgeintherelatedfield.Theconventionalgeargenerationprocesseslikeforming,shaping,hobbing,etc.areusuallyrepresentedintwo-dimensionalsketch.Theremaybesomecomponentsthatar

5、enotadequatelydescribedbythetwo-dimensionalapproach.Inthecaseofgeargeneration,itmaybedifficulttounderstandthecomplexgeometriesandthemanufacturingarrangementwiththehelpof2Dmodels.Theselimitationscanbepartiallyovercomeandunderstandingwillbemoremeaningfulifoneuses3Dsolidmodelsinstead.However,thedevelop

6、mentofthemodelsusing3Dsolidsmaynotalwaysensuretheclarityofthecomplexgeargenerationprocessunlessoneusesanimationtorepresenttilemotionofthegearblankandthegearcutter.Thiscanbeachievedveryefficientlywiththehelpofthevirtualmanufacturingtechnique.Itisatechnologytocreateavirtualenvironmentonthecomputerscre

7、entosimulatethephysicalworld.Theknowledgebaseandexpertisegainedfromtheworkinthevirtualenvironmentenablestheusertoapplythemmoremeaningfullyinreallifesituations.Ahostofliteratureisavailableonvirtualmanufacturingindifferentareasamongwhichsomeoftherecentandimportantworksarereferredbelow.TesicandBaneljee

8、1haveworkedintheareaofrapidprototyping,whichisanewtechnologyfordesign,visualizationandverification.Graphicaluserinterfaces,virtualrealitytechnologies,distillation,segregationandautointerpretationaresomeoftheimportantfeaturesoftheirwork.Balylissetal.2dealtwiththedevelopmentofmodelsinavirtualenvironme

9、ntusingthevirtualrealitytechnologiesprovidinganoutstanding3Dvisualizationoftheobject.In1994,G.M.Balylissetal.3presentedtheoreticsolidmodelingtechniquesusingtheVMtools,likeVP,MI,(virtualrealitymanufacturinglanguage)and3DSludioMax.Theyhavedevelopeddifferentpartsofanautomobileandthroughthespecialeffect

10、ofanimationimpartedallpossiblemotiontothemodel.ThetechnologyisfurtherenhancedbyKiulera4,whotreatedproductandprocessmodelingasakernelforthevirtualmanufacturingenvironment.Inhiswork,Kimurahasincorporatedsignificantmodelingissueslikerepresentation,representationlanguage,abstraction,standardization,conf

11、igurationcontrol,etc.ArangarasauandGadh5contributedtowardsthevirtualprototypingthatareconstructedusingsimulationoftheplannedproductionprocessusingvirtualmanufacturingonaplatformofMAYA,3DStudioMaxandVRML,etc.At.JadavpurUniversity,researchwork6,7isbeingcarriedouttosimulatethegearmanufacturingprocesses

12、usingAIIll)CADand31)StudioMaxasplatforms.Softwarehasbeendevelopedthathelpsthedesignengineerstounderstandtheproblemsrelatedtospurgearoperationanditsmanufacturingprocess.Astudyofthestateoftileartandliteraturereviewrevealthatthescopeofvirtualmanufacturingiswideopenforsimulatingspurgeargenerationprocess

13、es.Computersimulationcanbeveryeffectivelyusedforviewingalongwithaidingsubsequentanalysisofdifferentcomplicatedmanufacturingprocessesusingtheconceptofdesigncenteredvirtualmanufacturing.Withthisobjectiveinmind,anattemptismadetovirtuallymanufacturespurandhelicalgearsfromtheblankusingarackcutter.Thescop

14、eoftheworkincludesthegenerationofdesigndataforthespurandhelicalgearsandtherackformcutter,thegenerationofsolidmodelsforthecutterandblank,andfinallytosimulategear-manufacturingprocessthroughanimation.Themainmotivationoftheworkistosimplifythetaskofdesigning,andtostudythegeargenerationprocessthatcanbeun

15、derstoodbyalaymanandtopresentarealisticviewofit.Alltheprocessesaredevelopedontheplatformofthe3DStudioMax,whichisoneofthemostimportantvirtualtools.Thesoftwareisdevelopedusingmax-script,anobjectcontainedprogramminglanguagethatcanberunin3DStudioMaxenvironment.2DescriptionofthesoftwareThemax-scriptlangu

16、ageisbasicallyanimageprocessorthatcreatesthevisualeffectsin3DStudioMax.Inaddition,itcanbeusedfordesigncalculationandsubsequentchecking.Anattemptismadetodeveloptheentirepackageinmodularformsothatanyfurtherimprovementcanbeimplementedeasilywithoutaffectingtheothers.Theentireworkiscarriedoutina3Denviron

17、ment.ThemodularstructureoftheentirepackageispresentedinFig.l.Themajormodulesare:inputmodule,geardesignmodule,virtualmanufacturingmoduleandspecialmodule.Abriefdescriptionofthesemodulesismentionedbelow.2.1InputmoduleThismoduleisdevelopedtoprovideinputparametersthatareessentialfor(tiedesignanddevelopme

18、ntofthespurandhelicalgearsandthecorrespondingcutters.Inordertomakethesoftwareuserfriendly,theprocessofinputtingthedataisspecificallydonethroughaninputdialogue-boxcreatedbythemax-script-language.AsampledialogueboxisshowninFig.2.Somefieldshavesomerestrictionslikepredefinedlowerorupperlimitsorpredefine

19、dstepsforincrementordecrement.Thisisdonepurposivelytomaketheenvironmentmoreuserfriendlyandtorestricttheuserfromenteringinvaliddata,forexample,ausercannotmakethenumberofgearteethlessthan18.2.2Gear-designmoduleBeforegoingforthegenerationofthegears,oneshouldevaluatethevariousdesignparametersofthegearst

20、obemanufacturedbasedontheinputparameters.Inordertodesignagearpair,thefollowingdataareessential.IRpmatwhichthegearisrunning2.Thepowerbeingtransmitted3.ThetransmissionratiooftheassemblyInaddition,usersmayspecifythefollowingoperationalconditions/parameters:1.Precisionofthegearassembly2.Pressureangleoft

21、hegear3.Materialofthepinion4.Typeofshockloadrequiredforthepiniontotakeup5.HelixangleincaseofhelicalgearIftheuserisnotsatisfiedwiththeoutput,hecanmodifytheinputtoobtaindesiredoutput.Inthismodule,theentiredesignprocedureforthegearshasbeentreated.Thedifferentaspectsofdesigncalculations,forexample,dynam

22、icload,staticload(fatigueload)andthewearloadhavebeencalculatedinseparateprograms,andaredisplayedthroughtheoutputdialogbox.Whiledesigningthegear,ithasbeenkeptinmindthatthegearhastoformmeshwiththatoftherack,socarehasbeentakentoavoidtheinterferenceofthematingpair.2.2.1MethodologyVarietiesofgearcuttingp

23、rocessesareavailableandaregenerallybeingfollowedintheindustriesduringtheirmanufacturing.Inthispaper,Focusisgivenongearmanufacturingthroughgeneration.Theunderlyingprincipleofgeardesignisbasedonthefactthattheprofilesofapairofgearteethbearadefiniterelationshiptoeachothersuchthatthepairofteethhaveaprede

24、terminedrelativemotionandcontactateveryinstant.Therefore,iftherelativemotionoftheprofilesandtheformofoneofthemisknown,thedeterminationoftheformoftheothermayberegardedastileproblemcapableofsolutionbyeithergraphicaloranalyticalmeans.Theactualproductionofgeartoothrepresentsasolutiontotheaboveproblembym

25、echanicalmeansknownasgeneration.Thegenerationisamethodthatfollowsthefollowingprinciples.1.Acuttingedge(basicallyagearwithcuttingedges)isgivenamotion.Asaresult,itiscausedtosweepoutthesurfacecorrespondingtotheactualteethsurfacesoftheknownmemberofapairofconjugategears.2.Ablankismountedatanappropriatere

26、lationshiptothecutter.Itisgivenamotionthatthefinishedgearmusthaverelativetothatofthecutter.Asaresultofthesimultaneousmovementandthecuttingactionofthecutter,teethareformedontheblankconjugatetothatrepresentedbythecutter.Infactduetotheadditionoftherelativemotion,theprofilegiventotheworkpieceisdifferent

27、fromthatofthecutter.Thisdifferentiatesthegeneratingfromtheformingoperation.2.2.2SpurgearGenerationofspurgearbymeansofcuttercorrespondinginformtothematinggeariswellknown.Cuttermaybeintheformofarack.Foraninvolutesystemoftoothprofiles,thecuttercorrespondingtotherackwillhavestraightsides.Thearrangemento

28、fsuchacutterrelativetotheblankisshowninFig.3.Thecutterisadjustedradiallywithrespecttotheaxisofthework.Itisreciprocatedsothatitsedgesmaysweepoutthesurfaceoftheteethoftheimaginaryrackformingthebasisofthedesignofthetoothprofileoftheblank.Inadditiontothisreciprocation,thecutterisadvancedinthedirectionof

29、thepitchlineandatthesametimetheworkisrotatedaboutitsaxisataspeedsuchthatitispitchpointhasthesamelinearvelocityasthatoftherack.Inotherwords,thepitchcircleoftheblankandthepitchlineoftherackrolltogether.Inconsequencethestraightcuttingsedgesgeneratetheinvoluteprofileintheblank.Forsuchaprocesstobecontinu

30、ous,Thelengthofthecuttershouldbesomewhatlongerthanthepitchcircumferenceofthework；sincethisisusuallyimpracticableThecutteriswithdrawnfromtheworkafterithasadvancedadistanceequaltoallintegralnumberofpitchesandreturntoitsstartingpoint，theblankinthemeantimeremainsstationaryThisisrepeateduntilalltheteetha

31、recut2.2.3HelicalgearItiswellknownthatahelicalinvolutegearisconjugatetoastraightrackhavinginclinedteethTherefore，thesamemethoddescribedabovecanbeemployedtomanufactureahelicalgearHowever,thedirectionofreciprocationoftherackcuttermustbeinclinedtotheaxisoftheblankatallangleequaltothehelixangleofthegearThecuttermustrollovertheblankinadirectionsimilartothatdescribedearlierThesimultaneousmotioninvolvedandtheorientationof