CAD与CAPP集成技术.docx

CAD与CAPP集成技术.docx

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CAD与CAPP集成技术

DesignofaSTEPcompliantsystemforturningoperations

Thechangingeconomicclimatehasmadeglobalmanufacturingagrowingnecessityoverthelastdecade,forcingcompaniesfromEastandWesttocollaboratebeyondgeographicboundariesinthedesign,manufactureandassemblyofproducts.TheISO10303andISO14649Standards（STEPandSTEP-NC）havebeendevelopedtointroduceinteroperabilityintomanufacturingenterprisessoastomeetthechallengesofrespondingtoproductionondemand.ThispaperdescribesandillustratesaSTEPcompliantCAD/CAPP/CAMSystemforthemanufactureofrotationalpartsonCNCturningcenters.TheinformationmodelstosupporttheproposedsystemtogetherwiththedatamodelsdefinedintheISO14649standardusedtocreatetheNCprogramsarealsodescribed.AstructuredviewofaSTEPcompliantCAD/CAPP/CAMsystemframeworksupportingthenextgenerationofintelligentCNCcontrollersforturn/millcomponentmanufactureisprovided.FinallyaproposedcomputationalenvironmentforaSTEP-NCcompliantsystemforturningoperations（SCSTO）isdescribed.SCSTOistheexperimentalaspectoftheresearchandissupportedbyinformationmodelsthatandhavebeenconstructedusingastructuredmethodologyandobject-orientedmethods.SCSTOwasdevelopedtogenerateaPart21filebasedonmachiningfeaturestosupporttheinteractivegenerationofprocessplansutilizingfeatureextraction.AcasestudycomponenthasbeendevelopedtoprovetheconceptofusingthemillingandturningpartsofISO14649toprovideaturn-millCAD/CAPP/CAMenvironment.

Design-to-fabricationautomationforthecognitivemachineshop  

Tomeettherisingdemandsforpurecustomizationofproducts,newapproachesforautomatedfabricationofcustomizedpartgeometryareneeded,onboththesoftwareandhardwareside,thatbalanceflexibility,robustnessandefficiency.Thisisagreatchallengesincetodayitrequiressignificanthumanexpertisesupported,onlypartially,bycomputer-aidedapproaches.Thispaperintroducesanewapproachandframeworkforanautonomousdesign-to-fabricationsystemthatintegratescognitivecapabilities,suchasreasoningfromknowledgemodelsandautonomousplanning,andembedstheseinthemachinesthemselvestoautomaticallyfabricatecustomizedparts.Theframeworkintegratesintoacommonprocessautomaticworkpieceselectionusinganontology,generativeCNCmachiningplanningusingshapegrammarsandautomatedfixturedesign,basedonanovelflexiblefixturedevicehardware.Initialresultsaregivenforthemachiningplanningapproachappliedto2.5Dpartswithadefinedapproachdirectionandtheprototypedfixturedeviceispresented.Theadvantagesandpotentialoftheframeworkstemmainlyfromapplyingtheprinciplesofcognitivetechnicalsystemstoafabricationsystemtodevelopanintegratedandon-lineapproach.Themethodsaredevelopedspecificallyforuseonthemachineshopfloortotakeadvantageofthepossibilitytoupdateandextendknowledgemodelstoreflectcurrentfabricationcapabilitiesandtoadapttochangesintheenvironmentandre-planduringoperation.Finally,futuredirections,includingintegratingon-lineperceptionandlearning,arediscussed,whicharerequiredtocreateatrulyflexibleandcognitivefabricationsystem.

Areviewofautomatedfeaturerecognitionwithrule-basedpatternrecognition

Automatedfeaturerecognition（AFR）hasprovidedthegreatestcontributiontofullyautomatedCAPPsystemdevelopment.TheobjectiveofthispaperistoreviewvariousapproachesforsolvingthreemajorAFRproblems:

（i）extractionofgeometricprimitivesfromaCADmodel;（ii）definingasuitablepartrepresentationforformfeatureidentification;and（iii）featurepatternmatching/recognition.Anovel,detailedclassificationofdevelopedAFRsystemshasbeenintroduced.Thispaperalsoprovidesathoroughinvestigationofmethodsforgeometricfeatureextraction,emphasizingSTEPstandardapplicationand,finally,areviewofrecentresearchreportsinthefieldofAFRwithrule-basedfeaturepatternrecognition.Wediscusspotentialsandlimitationsoftheseapproachesandemphasizedirectionsforfurtherresearchwork.

Computeraidedmanufacturabilityanalysis:

Closingtheknowledgegapbetweenthedesignerandthemanufacturer 

Manufacturingtodayismarkedbyincreasedcompetitionanddispersedglobalorganization,thusnecessitatingenhancedcollaborationamongdesignersandmanufacturers.Nevertheless,whileDesignforManufacturability（DFM）hasbeenthesubjectofin-depthresearchoverthepastdecades,thesupportingsoftwaresolutionshavenotasyetmatured.Inthispaperwepresentaholisticapproachandsupportingsoftwaretool,termedtheComputerAidedManufacturabilityAnalysis（CAMA）tool,forcapitalizingonavailablemanufacturabilityknowledge.Thisisachievedbyclosingtheknowledgeloopbetweenthedesignandmanufacturingenvironments.CAMAcapturestheknowledgeinastructuredmannerandincorporatesthisknowledgewithintheproductdesigntools（CADsystems）,thusenablingimprovedproducttimelinessandprofitability.CAMArepresentsproofofconceptandconstitutesademonstrativeprototypeofanadaptiveandopenDFXtool.ItisbasedonindustrialsurveysoftheKnowledge,InformationandData（KID）flowsinCAD,CAPPandCAMprocesseswithinthemanufacturingoutsourcingenvironment.CAMAdiffersfromotherapproachesinthatitisanopensystemthatenablescontinuousandintuitivecapture,modificationandimplementationofupdatedmanufacturabilityKID.

ISO14649-basednonlinearprocessplanningimplementationforcomplexmachining  

Increasingattentionisbeingpaidtocompletemachining,i.e.,machiningofthewholepartinasinglemachinetool,inthemetalworkingindustry.Forthispurpose,complexmachinetoolsequippedwithmachiningcomponents,suchasmultiplespindlesandturretshavebeendevelopedbyleadingmachinetoolbuilders.Theefficiencyofcomplexmachinetoolsislargelydependentonhowthemachiningcomponentsareutilized.Themainthrustofthispaperistwofold:

（1）PropositionofanonlinearprocessplanningbasedontheSTEP-NC（STEP-compliantdatainterfacefornumericalcontrols）paradigmwhosedatamodelisformalizedasISO14649,and

（2）Developmentofanoptimalsolutionalgorithmforprocessplanningforcomplexmachining.Thedevelopedalgorithmisbasedonthebranch-and-boundapproachandheuristicsderivedfromengineeringinsights.ThedevelopedprocessplanningmethodandoptimizationalgorithmwereimplementedandtestedviatheTurnSTEPsystemdevelopedbyourresearchteam.Throughtheexperiments,weareconvincedthatthenewprocessplanningandalgorithmcanbeusedasafundamentalmeansforimplementingthethirdtypeofSTEP-NC[SuhS.TurnSTEP:

ToolstocreateCNCturningprograms.In:

WhitepaperpresentedonSTEPImplementers’ForumISOTC184/SC4Meeting.2004],i.e.,anIntelligentandAutonomousSTEP-NCsystemfortheCAD-CAM-CNCchainsupportinge-Manufacturing.

Motionnavigationforarcweldingrobotsbasedonfeaturemappinginasimulationenvironment  

Theefficiencyoftheoff-lineprogrammingforthearcweldingrobotsdependsonthecomplexityoftheworkpiecesandtheweldingexperienceofthetechnician.Whentheworkpiecesorfixturesareredesignedortherobotworkstationlayoutischanged,theresultofprioroff-lineprogrammingcannotbereused.WiththethoughtofCAD/CAPP/CAMintegration,thispaperpresentsafeaturemappingalgorithm,whichconvertsthedesignfeaturesoftheworkpiecestothemachiningfeaturesoftheseams.Thenamotionnavigationmethodbasedonfeaturemappinginasimulationenvironmentisproposed.Thismethodcomprisesinitialpositionguidingandseamtracking.Forinitialpositionguiding,amotionpathwiththeleastenergyconsumptionisgeneratedbasedontheweightedoptimalcontrol;thenthepathisrevisedforavoidingobstaclesbysettingthepathtagsdynamically.Forseamtracking,theseamisdispersedintodiscreteweldingpoints;thentheweldinggunmovesthrougheachpointaccordingtotheweldingsequence.Themethodisimplementedinthedevelopmentofanoff-lineprogrammingsimulationsystem.Industrialcasesoftheweldingrobotworkcelllayoutforautomobiledoorframesshowthemethodcanmaketheoff-lineprogrammingmuchmoreeffective.

Anartificialintelligenceplanningapproachtomanufacturingfeaturerecognition  

Withinmanufacturing,featureshavebeenwidelyacceptedasusefulconcepts,andinparticulartheyareusedasaninterfacebetweenCADandCAPPsystems.Previousresearchonfeaturerecognitionfocusontheissuesofintersectingfeaturesandmultipleinterpretations,butdonotaddresstheproblemofcustomfeaturesrepresentation.Representationoffeaturesisanimportantaspectformakingfeaturerecognitionmoreapplicableinpractice.Inthispaperahybridproceduralandknowledge-basedapproachbasedonartificialintelligenceplanningispresented,whichaddressesbothclassicfeatureinterpretationandalsofeaturerepresentationproblems.STEPdesignsarepresentedascasestudiesinordertodemonstratetheeffectivenessofthemodel.

Applicationofgeneticalgorithmtocomputer-aidedprocessplanninginpreliminaryanddetailedplanning 

Computer-aidedprocessplanning（CAPP）isanimportantinterfacebetweencomputer-aideddesign（CAD）andcomputer-aidedmanufacturing（CAM）inthecomputerintegratedmanufacturing（CIM）environment.Agoodprocessplanofapartisbuiltupbasedontwoelements:

（1）optimizedsequenceoftheoperationsofthepart;and

（2）optimizedselectionofthemachine,cuttingtoolandtoolaccessdirection（TAD）foreachoperation.Ontheotherhand,twolevelsofplanningin