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INTJADVMANUFTECHNOL2000167397472000SPRINGERVERLAGLONDONLIMITEDAUTOMATEDASSEMBLYMODELLINGFORPLASTICINJECTIONMOULDSXGYE,JYHFUHANDKSLEEDEPARTMENTOFMECHANICALANDPRODUCTIONENGINEERING,NATIONALUNIVERSITYOFSINGAPORE,SINGAPOREANINJECTIONMOULDISAMECHANICALASSEMBLYTHATCONSISTSOFPRODUCTDEPENDENTPARTSANDPRODUCTINDEPENDENTPARTSTHISPAPERADDRESSESTHETWOKEYISSUESOFASSEMBLYMODELLINGFORINJECTIONMOULDS,NAMELY,REPRESENTINGANINJECTIONMOULDASSEMBLYINACOMPUTERANDDETERMININGTHEPOSITIONANDORIENTATIONOFAPRODUCTINDEPENDENTPARTINANASSEMBLYAFEATUREBASEDANDOBJECTORIENTEDREPRESENTATIONISPROPOSEDTOREPRESENTTHEHIERARCHICALASSEMBLYOFINJECTIONMOULDSTHISREPRESENTATIONREQUIRESANDPERMITSADESIGNERTOTHINKBEYONDTHEMERESHAPEOFAPARTANDSTATEEXPLICITLYWHATPORTIONSOFAPARTAREIMPORTANTANDWHYTHUS,ITPROVIDESANOPPORTUNITYFORDESIGNERSTODESIGNFORASSEMBLYDFAASIMPLIFIEDSYMBOLICGEOMETRICAPPROACHISALSOPRESENTEDTOINFERTHECONFIGURATIONSOFASSEMBLYOBJECTSINANASSEMBLYACCORDINGTOTHEMATINGCONDITIONSBASEDONTHEPROPOSEDREPRESENTATIONANDTHESIMPLIFIEDSYMBOLICGEOMETRICAPPROACH,AUTOMATICASSEMBLYMODELLINGISFURTHERDISCUSSEDKEYWORDSASSEMBLYMODELLINGFEATUREBASEDINJECTIONMOULDSOBJECTORIENTED1INTRODUCTIONINJECTIONMOULDINGISTHEMOSTIMPORTANTPROCESSFORMANUFACTURINGPLASTICMOULDEDPRODUCTSTHENECESSARYEQUIPMENTCONSISTSOFTWOMAINELEMENTS,THEINJECTIONMOULDINGMACHINEANDTHEINJECTIONMOULDTHEINJECTIONMOULDINGMACHINESUSEDTODAYARESOCALLEDUNIVERSALMACHINES,ONTOWHICHVARIOUSMOULDSFORPLASTICPARTSWITHDIFFERENTGEOMETRIESCANBEMOUNTED,WITHINCERTAINDIMENSIONLIMITS,BUTTHEINJECTIONMOULDDESIGNHASTOCHANGEWITHPLASTICPRODUCTSFORDIFFERENTMOULDINGGEOMETRIES,DIFFERENTMOULDCONFIGURATIONSAREUSUALLYNECESSARYTHEPRIMARYTASKOFANINJECTIONMOULDISTOSHAPETHEMOLTENMATERIALINTOTHEFINALSHAPEOFTHEPLASTICPRODUCTTHISTASKISFULFILLEDBYTHECAVITYSYSTEMTHATCONSISTSOFCORE,CAVITY,INSERTS,ANDSLIDER/LIFTERHEADSTHEGEOMETRICALSHAPESCORRESPONDENCEANDOFFPRINTREQUESTSTODRJERRYYHFUH,DEPARTMENTOFMECHANICALANDPRODUCTIONENGINEERING,NATIONALUNIVERSITYOFSINGAPORENUS,10KENTRIDGECRESCENT,SINGAPORE119260EMAILMPEFUHYHKNUSEDUSGANDSIZESOFACAVITYSYSTEMAREDETERMINEDDIRECTLYBYTHEPLASTICMOULDEDPRODUCT,SOALLCOMPONENTSOFACAVITYSYSTEMARECALLEDPRODUCTDEPENDENTPARTSHEREINAFTER,PRODUCTREFERSTOAPLASTICMOULDEDPRODUCT,PARTREFERSTOTHECOMPONENTOFANINJECTIONMOULDBESIDESTHEPRIMARYTASKOFSHAPINGTHEPRODUCT,ANINJECTIONMOULDHASALSOTOFULFILANUMBEROFTASKSSUCHASTHEDISTRIBUTIONOFMELT,COOLINGTHEMOLTENMATERIAL,EJECTIONOFTHEMOULDEDPRODUCT,TRANSMITTINGMOTION,GUIDING,ANDALIGNINGTHEMOULDHALVESTHEFUNCTIONALPARTSTOFULFILTHESETASKSAREUSUALLYSIMILARINSTRUCTUREANDGEOMETRICALSHAPEFORDIFFERENTINJECTIONMOULDSTHEIRSTRUCTURESANDGEOMETRICALSHAPESAREINDEPENDENTOFTHEPLASTICMOULDEDPRODUCTS,BUTTHEIRSIZESCANBECHANGEDACCORDINGTOTHEPLASTICPRODUCTSTHEREFORE,ITCANBECONCLUDEDTHATANINJECTIONMOULDISACTUALLYAMECHANICALASSEMBLYTHATCONSISTSOFPRODUCTDEPENDENTPARTSANDPRODUCTINDEPENDENTPARTSFIGURE1SHOWSTHEASSEMBLYSTRUCTUREOFANINJECTIONMOULDTHEDESIGNOFAPRODUCTDEPENDENTPARTISBASEDONEXTRACTINGTHEGEOMETRYFROMTHEPLASTICPRODUCTINRECENTYEARS,CAD/CAMTECHNOLOGYHASBEENSUCCESSFULLYUSEDTOHELPMOULDDESIGNERSTODESIGNTHEPRODUCTDEPENDENTPARTSTHEMOULDMOULDBASECOOLFILLLAYOUTPLUGSOCKETCAV_1CAV_2CAPLATEGUILDBUSHTCPPLATEBEPPLATECBPLATEEAPLATEEBPLATEGUIDPINIPPLATERETPINSLIDERBODYGUIDESTOPBLKHEELBLKHEADCORECAVITYPRODUCTINDEPENDENTPARTPRODUCTDEPENDENTPARTMOVEHALFFIXEDHALFFIG1ASSEMBLYSTRUCTUREOFANINJECTIONMOULD740XGYEETALAUTOMATICGENERATIONOFTHEGEOMETRICALSHAPEFORAPRODUCTDEPENDENTPARTFROMTHEPLASTICPRODUCTHASALSOATTRACTEDALOTOFRESEARCHINTEREST1,2HOWEVER,LITTLEWORKHASBEENCARRIEDOUTONTHEASSEMBLYMODELLINGOFINJECTIONMOULDS,ALTHOUGHITISASIMPORTANTASTHEDESIGNOFPRODUCTDEPENDENTPARTSTHEMOULDINDUSTRYISFACINGTHEFOLLOWINGTWODIFFICULTIESWHENUSEACADSYSTEMTODESIGNPRODUCTINDEPENDENTPARTSANDTHEWHOLEASSEMBLYOFANINJECTIONMOULDFIRST,THEREAREUSUALLYAROUNDONEHUNDREDPRODUCTINDEPENDENTPARTSINAMOULDSET,ANDTHESEPARTSAREASSOCIATEDWITHEACHOTHERWITHDIFFERENTKINDSOFCONSTRAINTSITISTIMECONSUMINGFORTHEDESIGNERTOORIENTANDPOSITIONTHECOMPONENTSINANASSEMBLYSECONDLY,WHILEMOULDDESIGNERS,MOSTOFTHETIME,THINKONTHELEVELOFREALWORLDOBJECTS,SUCHASSCREWS,PLATES,ANDPINS,THECADSYSTEMUSESATOTALLYDIFFERENTLEVELOFGEOMETRICALOBJECTSASARESULT,HIGHLEVELOBJECTORIENTEDIDEASHAVETOBETRANSLATEDTOLOWLEVELCADENTITIESSUCHASLINES,SURFACES,ORSOLIDSTHEREFORE,ITISNECESSARYTODEVELOPANAUTOMATICASSEMBLYMODELLINGSYSTEMFORINJECTIONMOULDSTOSOLVETHESETWOPROBLEMSINTHISPAPER,WEADDRESSTHEFOLLOWINGTWOKEYISSUESFORAUTOMATICASSEMBLYMODELLINGREPRESENTINGAPRODUCTINDEPENDENTPARTANDAMOULDASSEMBLYINACOMPUTERANDDETERMININGTHEPOSITIONANDORIENTATIONOFACOMPONENTPARTINANASSEMBLYTHISPAPERGIVESABRIEFREVIEWOFRELATEDRESEARCHINASSEMBLYMODELLING,ANDPRESENTSANINTEGRATEDREPRESENTATIONFORTHEINJECTIONMOULDASSEMBLYASIMPLIFIEDGEOMETRICSYMBOLICMETHODISPROPOSEDTODETERMINETHEPOSITIONANDORIENTATIONOFAPARTINTHEMOULDASSEMBLYANEXAMPLEOFAUTOMATICASSEMBLYMODELLINGOFANINJECTIONMOULDISILLUSTRATED2RELATEDRESEARCHASSEMBLYMODELLINGHASBEENTHESUBJECTOFRESEARCHINDIVERSEFIELDS,SUCHAS,KINEMATICS,AI,ANDGEOMETRICMODELLINGLIBARDIETAL3COMPILEDARESEARCHREVIEWOFASSEMB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