Three-Dimensional-Kernel-Development-for-Injection

IntJAdvManufTechnol(2001)17:453–4612001Springer-VerlagLondonLimitedThree-DimensionalKernelDevelopmentforInjectionMouldDesignT.L.NeoandK.S.LeeDepartmentofMechanicalandProductionEngineering,NationalUniversityofSingapore,SingaporeToday,manysoftware“plug-ins”havebeendevelopedonhigh-level3DmodellingplatformstofacilitateprocessessuchasFEManalysis,CAM,injectionmoulddesign,simulationandvisualisation.Suchanarrangementisadvantageousinmanyways.However,itisnotwithoutshortcomings.Ideally,these“plug-ins”couldalsobedevelopedusinglow-level3Dkernelsforhigherflexibilityandbetterportability.Thispaperexaminesthevariousissuesandmethodologiesrelatedtothedevelopmentofsuch3D-basedapplications.Theemphasisisplacedonthesoftwareaspect.First,amethodologyforthedevelopmentof3D-basedapplicationsisproposed.Theideaisthenimplementedbydevelopinganinjectionmoulddesignapplicationusingalow-level3DkernelcalledParasolid.Basedondesignconceptsusedinanestablishedmoulddesignappli-cation,IMOLD,thedevelopmentofamouldbasedesignmoduleisillustrated.Anobject-orientedprogramminglangu-agehasbeenchosenforthedevelopmentofthesoftwareonaWindowsNTplatform.Keywords:3Dkernel;Computer-aideddesign(CAD);Injec-tionmoulddesign;Parasolid1.IntroductionThree-dimensionalCADsystemshaveincreasinglybeenusedtospeeduptheproductrealisationprocess.Oneofthefirststepsinvolvedintheautomationoftheproductdesignprocessisthecreationofthecomponentpartsina3Dmodellingapplication.The3Dmodel,uponcreation,iscalledthedigitalmastercopy.This3Ddigitalmodelformsthekeytoawidespectrumofprocessautomation.Creatingthe3Ddigitalmodelofcomponentpartsisonlytheveryfirststep.Thereareseveralothersecondarytasksthatmusttobedonebeforethepartcanbemanufactured.Suchtasksincludefinite-elementanalysis,jigsandfixturesdesign,injectionmoulddesign,computer-aidedmanufacturing,simul-Correspondenceandoffprintrequeststo:K.-S.Lee,DepartmentofMechanicalandProductionEngineering,NationalUniversityofSinga-pore,119260Singapore.E-mail:mpeleeksKnus.edu.sgation,andvisualisation.Today,manyapplicationPlug-inshavebeendevelopedonhigh-level3Dmodellingplatformstofacili-tatethesesecondarytasks.The3D-modellingplatformprovidestheplug-insoftwarewithalibraryoffunctionsaswellasanestablisheduserinterfaceandstyleofprogramming.Asaresult,thedevelopmenttimesfortheseplug-insaresignifi-cantlyreduced.Suchanarrangementisadvantageousinmanyways.How-ever,ithasitsshortcomings,especiallyinthelongrun.Inordertodevelopaplug-inforestablishedsoftware,thedevel-opersmustadheretothemanyconstraintsimposed.Thereisaneedtobeconsistentwiththestyleoftheparentsoftware.Thedevelopersmustbeabletoachieveanyfunctionalitytheyneedwithonlythesetoflibraryfunctionsprovided.Mostend-usersneedboththeparentsoftwareandtheplug-in.Inmanycases,however,theymaybemoreinterestedinusingonlytheplug-insoftware.Anexampleofsuchasituationisininjectionmoulddesign.Theseusers,however,mustpurchasetheentiresoftwarepackagewhichincludesmanyfeaturesandfunctionsthattheydonotneed.Suchalargeprogramisoftenverydemandingonthehardware,whichalsomeanshighercost.Theplug-insoftwareisalsoverydependentondevelopmentsintheparentsoftware.Wheneveranewversionisupdatedfortheparentsoftware,theplug-indevelopershavetofollow-uponthechanges.Theseshortcomingsmaynotexistiftheseapplicationsweredevelopedonalow-levelplatform.Ideally,theseplug-inscouldbedevelopedusinglow-level3Dkernelsforhigherflexibilityandbetterportability.Inmanyinstances,suchamoveisbothfeasibleandadvantageous.Traditionally,injectionmoulddesigniscarriedoutdirectlyonaCADsystem.Theentireinjectionmould,consistingofperhapshundredsofcomponents,ismodelledandassembledonCADsystemssuchasAutoCAD,Pro/Engineer,andUni-graphics.Astheinjectionmoulddesignprocessisrecursive,itisverytime-consumingtore-modelandre-assemblethedesign.Inthisaspect,3DCADsystemssuchasPro/EngineerandUnigraphics,whicharefeature-based,haveasignificantadvantageover2DCADsystemssuchasAutoCAD.Tofurtherspeeduptheinjectionmoulddesignprocess,plug-insweredevelopedonthese3Dsystemstoautomatecertainstagesofthedesignprocess.Examplesofsuchadd-onapplicationsincludeIMOLD(IntelligentMoldDesignandAssemblySys-454T.L.NeoandK.S.Leetem,developedattheNationalUniversityofSingapore,basedonUnigraphics),ExpertMoldDesigner(basedonCADKEY)andMoldmaker(basedonEUCLID).AseachisbasedonaspecificCADsystem,thereisnoplugcompatibility.In1994,MokandCheung[1]presentedworkonthedevel-opmentofaninjectionmoulddesignapplicationbasedonUnigraphics.In1997,Shah[2]proposeda3-tierarchitectureforstandardisingcommunicationsbetweengeometricmodellingkernelsandapplicationsthatrequiregeometricmodellingser-vices.Hisobjectiveistoachieveplugcompatibilitybetween3DapplicationsthatarebasedonParasolid[3](a3Dkernel,developedattheUniversityofCambridge)andACIS.This,however,involvedanextensivelydeveloped3-tiermodellinghusk.Inthispaper,theauthorattemptstodevelopalightweightinjectionmoulddesignapplicationusingalow-level3Dkerneldirectly.Thefocusisontheflexibilityandspeedofthesoftwaredevelopment.DesignconceptsandproceduresweretakenfromIMOLD[4,5],acompletemoulddesignandassembly3Dapplication.Altho