CATIA破面修复教程

CopyrightDASSAULTSYSTEMES20021HealingAssistantCATIATrainingFoilsVersion5Release9June2002EDU-CAT-E-HA1-FF-V5R9CopyrightDASSAULTSYSTEMES20022CoursePresentationObjectivesofthecourseInthiscourseyouwilllearnwhy,whenandhowtousetheapplicationHA1HealingAssistantTargetedaudienceAlldesigners,especiallytoolingdesignersPrerequisitesWireframe&SurfaceDesign0.5DayCopyrightDASSAULTSYSTEMES20023TableofContents1.IntroductiontoHealingAssistantp.4Whydoyouneedhealing?p.5SomeinformationontheJoinoperatorp.6Howtochooseamergingdistancep.92.Workbenchpresentationp.11Accessingtheworkbenchp.12Theuserinterfacep.13Methodologyforhealingp.143.ModelanalysiswithHealingAssistantp.15FaceCheckerp.16SurfaceConnectionCheckerp.174.CreatingTopologyp.20Repairinginvalidsurfacesp.21FaceSmoothp.22Repairingbadtopologysituationsp.23Checkingforfreesidesp.245.Closingatopologyp.27Fixingfreesidesp.28LocalJoinp.31Thehealingoperatorp.32LocalHealingp.33CopyrightDASSAULTSYSTEMES20024IntroductiontoHealingAssistantInthislesson,youwillseesomegeneralinformationabout:TheNeedforHealingTheJoinOperatorTheMergingDistanceCopyrightDASSAULTSYSTEMES20025Healing=processofcreatingavalidV5closedmodeloutofanytypeofdata,evennotvalidProblemslinkedtoimporteddata:-accuracyuncontrolled-validitycriteriadifferentfromthoseofV5-dataqualitydowngradedduringtransfer-usermishandling(losses,duplications,…)WhyDoYouNeedHealing?Foreigndata:IGES,STEP,CATIAV4,otherClosedmodelToolingDesignNCManufacturingRapidPrototypingAdditionalDesignSimulationCopyrightDASSAULTSYSTEMES20026STEP1isdoneconsideringatoleranceparametercalledmergingdistance.Allsurfaceboundariesarecomparedtofindthosewhicharecloseenoughtobecomesharededges.PROBLEM:surfaceboundarycurvesarenotalwayscleanenoughtosortoutthesharededgesSomeInformationontheJoinOperator(1/3)JOINisthemainoperatorforthecreationoftopologyJoiningsurfacesisdonein2stepsd12•d0.001mm(systemtolerance):edgeisshared(geometricallyclosed)•0.001mmdmergingdistance:edgeisshared(onlytopologicallyclosed)•dmergingdistance:edgeisnotshared,boundariesremainfreesidesSTEP2consistsingivingconsistentorientationstofaceswhichhaveasharededge.PROBLEM:itisnotalwayspossibletopropagateaconsistentorientationallovertheJoin.Surface2isincludedtotheJoinwithaflagspecifyingthattheorientationofthefaceisopposedtotheorientationoftheoriginalsurface(thesurfaceitselfisnotchanged)12CopyrightDASSAULTSYSTEMES20027Problem1:examplesofsurfaceswithself-intersectingedgesMostcommoncase:surfaceswithathinarea.Dependingontherequestedmergingdistance,edgesinthethinareaareconsideredassuperimposed(impossibletofindasinglecommonvertex).Thissituationmaydisappearifthemergingdistanceisdecreased.Othersituationswhichmayexistinimporteddata:SomeInformationontheJoinOperator(2/3)Incorrectboundary(theshadeddisplayisalsoincorrect)Verysmallcurvesintheboundary(givesamultiplevertex)Notsupportedtopology(example:surfacelyingonaclosedsurface)CopyrightDASSAULTSYSTEMES20028Problem2:examplesofbadtopologyMostcommoncase:smalloverlapOthercase:noinside/outsidedefinitionpossible(Moebiustypesituation)SomeInformationontheJoinOperator(3/3)Theedgeisshared(dmergingdistance)Theorientationofsurface2issetaccordingtotheorientationofsurface1,butthereisanambiguity(cuspornocusp?).Ifthewrongdirectionischosen,aninconsistencymayappearlater.ThissituationmaydisappeariftheMergingdistanceisincreased.d12??Itisnotpossibletodefineaconsistentorientationalloverthesurface.123??Forexample,theinconsistencymayappearwhenaddingsurface3tothejoin.CopyrightDASSAULTSYSTEMES20029HowtoChooseaMergingDistance(1/2)youmusttakeintoaccounttheaccuracyofthedatatoJoin:ifyouchooseastricttolerance,theJoinhasmanyfreesidesandittakestimetocorrectthemalsosometimesJoindoesnotworkwithastricttolerance(badtopology)Ontheotherhandifyoureleasethetolerancetoomuch,somegapsarehiddenbutthegeometrystillhasgapsandmaybeunusableforlaterprocessingForexamplegapsmaycausevisiblemarksonthemanufacturedpartrememberthatagapmaybe:or:finallyJoinremovesalledgeswhicharesmallerthanthemergingdistance,whichcancauseproblemsifthemergingdistanceistoohighThesuppressionofsmallcurvesmaylaterproduceinvalidfaces(withself-intersectingedges)mergingdist.=0.001mmmergingdist.=0.01mmmergingdist.=0.1mmCopyrightDASSAULTSYSTEMES200210Practicaltips:StartwithalowvalueofthemergingdistanceIncreasethevalueonlyifneededtoavoidbadtopologiesOnceyouhaveaJoinyoumaystillincreasethevalueofthemergingdistancetohidegaps(onthetopologylevel);doitbycreatinganewJoinratherthanbymodifyingthefirstone,inordertoavoidsuppressingsmalledgecurvesDonotincreasethevaluetoomuch,ifneededuseHealingAssistanttofindtheinvalidtopologicalsituations(surfaceconnectionchecker)toclosetheremainingfreesides(LocalJoin,LocalHealing)HowtoChooseaMergingDistance(2/2)Joinat0.001mmIfbadtopology:IncreasevalueLimit=0.01to0.05mmIfbadtopologypersists:AnalyseandrepairproblemsIftoomanyfreesides:CreateJoinofJoinwithbiggervalueLimit=0.01to0.05mmIfremainingfreesides:AnalyseandcloseClosedtopologySTARTCopyrightDASSAULTSYSTEMES200211WorkbenchPresentationInthislesson,youwilllearnabout:TheAccesstotheHealingA