Expert system for multi-stage cold-forging process

JournalofMaterialsProcessingTechnologyELSEVIERJournalofMaterialsProcessingTechnology54(1995)271-285Expertsystemformulti-stagecold-forgingprocessdesignwithare-designingalgorithmHong-SeokKim,Yong-TaekIm*DepartmentofMechanicalEngineering,KoreaAdvancedInstituteofScienceandTechnology,373-1,Kusung-dong,Yusong-gu,Taejon305-701,SouthKoreaReceived19May1994IndustrialsummaryColdforginghasrecentlybecomeoneofthecompetitivetechnologiesinmanufacturing.Inordertoimpovetheproductivityofcoldforgingatlowproductioncost,anintegratedsystemsapproachisnecessaryinhandlingthematerialpreparationandtheoptimumprocessdesignconsideringtheformingmachines,tooling,andoperation,includingqualitycontrol.Asthefirststeptowardthisapproach,anexpertsystemformulti-stagecold-forgingprocessdesignforaxi-symmetricgeometrieswithorwithoutaholeinoneendhasbeendevelopedusingProloglanguageonIBM486PC.Thesystemconsistsofauserinterface,asystemshell,amaterialdata-base,andadesignrule-base.Accordingtothegiveninputdata,thesystemgeneratestheforgeablegeometryandthebasicprocessdesign,dependingontheinitialbilletsizeandmaterialortheorderofupsettingandforwardextrusion.Inaddition,itcanprovideaflexibleprocessre-designbasedoneitherthereductioninthenumberofformingsequencesbycombiningthepossibletwoprocessesinsequence,orthereductionofdeviationofthedistributionandtheleveloftherequiredformingloadsatthelastforgingstepbycontrollingtheformingratios.TherequiredformingloadsandglobalstraindistributionsateachsteparecalculatedanddisplayedonaPCmonitor.ThedesignedprocesssequencescanbeobtainedbyAutoCADoratextfileincludingthedimensionsofthedrawing.Thesystemdevelopedwillbeusefulinreducingtrial-and-errorbydesignengineersindeterminingthediameterandheightoftheinitialcyclindricalbilletfromthefinalproductgeometryandtheintermediatenecessarysequences.1.IntroductionMulti-stagecoldforgingofaxi-symmetricpartscon-sistsofseveralprocessesofshearing,sizing,upsettingorheading,forwardandbackwardextrusion,punching,etc.Theprocessdesigndependsonthecharacteristicsofsuchprocesses.Coldforginghasitsmajoradvantagesformakingaxi-symmetricpartsofsmallormediumsizesonmulti-stageautomaticforgingmachinesoronconven-tionalpressesinseveralsteps.Itcanproducepartswithgoodsurfacefinish,dimensionalaccuracyandimprovedmechanicalproperties,andalsoeliminateextrapost-pro-cessingsuchastrimmingandmachining.However,theeconomyofproducingdefect-freecold-forgedpartsreliesonthemechanismofthediedesignofthesequentialprocesses,whichhasbeenheavilydependentonthelevelofskillofdiedesignengineersbasedontheirworkingexperience.Therefore,theautomaticdesignofprocesssequencesformulti-stagecoldforgingoperationsisofimportance.*Correspondingauthor.0924-0136/95/$09.50©1995ElsevierScienceS.A.AllrightsreservedSSDI0924-0136(94)01774-UAccordingtorecentdevelopmentofcomputertechno-logy,theapplicationofcomputersinmanufacturinghasbeengrowingrapidlyintheareaofCAD/CAM(Com-puterAidedDesign/ComputerAidedManufacturing),CAE(ComputerAidedEngineering),CAPP(ComputerAidedProcessPlanning),andnumericalsimulationsofmanufacturingprocessesusingnumericaltechniques.Intheareaofprocessplanningofformingprocesses,anum-berofdevelopmentshavebeenreportedafterpioneeringworkbyNiebel[1]andBarker[2]inthelate1960s.Inthe1970s,AkgermanandAltan[3]developedaCADsystemforhotforging,BiswasandKnight[4]extendingtheirwork.Thesystemdevelopedis,ingeneral,com-posedofseveralmodulestoassisttheusersingeneratingforgingdesignrulesthatareincorporatedintothepro-gramsandformulatedonthebasisofgroupingrelationsandprocesslimitationsrelevanttoeachoperations[5-12].Inaddition,duetothedevelopmentofknowledgetreatmenttechnique,knowledgebasedmanufacturingsystemshavebecomepopular,basedonqualitativeandambiguoushumanexperiences.Inthesesystems,expertsystem[13],neuralnetworkorfuzzytheory[14,15],and272H,-S.Kim,E-T.Im/JournalofMaterialsProcessingTechnology54(1995)27l285artificalintelligence[16]areusedwiththehelpoftheoperator'sskill.Itiswidelyknownthattheexpertsystemhasemergedasoneofthemostactiveandfruitfulareasforresearchintheapplicationofhumanknowledgeforproblemswhichdonotlendthemselvestosolutionbyconventionalmethodsbecauseofalackofquantitativedataregardingtheinputoutputrelations.Expertsys-temscanthereforeprovideauser-friendly,flexible,intelli-gentsolutiontothekindofprobleminvolvingcomplexlogicwhichoccursinengineering,automaticgenerationofsequencedesignformulti-stagecoldforgingbeingagoodexample.Inthepresentinvestigation,anexpertsystemthatcandeterminethenumberandthegeometriesoftheinter-mediatestepsinthemulti-stagecoldforgingofaxi-sym-metricgeometrieswithorwithoutaholeinoneendhasbeendeveloped,theprogrambeingdevelopedusingProloglanguageonaIBM486PC.Thesystemconsistsofauserinterface,asystemshell,amaterialdata-base,andarule-base.Thesystemshellhasgraphic,inputandoutputmodules,aninferenceengineandaworkingmem-ory.Inordertomakethesystemmoreflexible,thematerialdatabaseandrule-baseareseparatedfromthesystemshell,beingobtainedfrommaterialshandbooks,references,andinterviewswithdie-designengineers[-17,18].Accordingtothegiveninputdata,theexpertsyst