MARC公司官方培訓手冊2005

MSC.Marcversion2005TrainingMACHINING

ShengPingWang

MSC.MarcDevelopment

FEMSimulationofNCMachiningProcesses

ObjectivesTopredicttheeffectsofinsituresidualstressredistributionduetocomplex3Dmachiningofbulkcomponents.Tostreamlineprocessdesignsoastominimizepartfit-upissues.Bottomline:Toreducemanufacturingcycletimetherebyachievingproductivityimprovementandcostsavings.FEMSimulationofNCMachiningProcesses

ApproachPseudo-simulationofmachiningprocessthroughautomatedmaterialremovalusingNCcuttingfiles(aptorclfiles)asinput.

AssumptionAprioriresidualstressesindepthofwork-pieceinfluenceresultingdistortionsmorethansurfaceresidualstressesintroducedbycuttingprocess.

CompaniesthathavebeenusingApproachBoeing,UTC(Sikorsky),Embraer,Picheney

ProductSolver-MSC.Marc2005GUI-MSC.MarcMentat2005MaterialRemovalSimulationMaterialtoberemovedMaterialtoberemovedBeam#1MaterialRemovalSimulationFlowchart

FEModel(FEAInputData)FEAResults(Post-processing)NC/CADDATA(CutterPath-apt,clfiles)InitialStressCAD/CAMSystemFEASolver(MSC.Marc)SolutionProcedureNCDataInterfaceInitialResidualStressInputFESolutionVisualizationNC/CADData

CUTTER/2.000000,.312000,.688000,.312000,.000000,$.000000,4.000000TLAXIS/.000000,.000000,1.000000FEDRAT/50.0000GOTO/20.00000,20.00000,20.00000PT1PPRINT************************************************************PPRINTLOAD2"DIAFACEMILLWITH.312CORNERRADIUSPPRINT************************************************************LOADTL/230002,LENGTH,0,OSETNO,1SPINDL/9963,CLWCOOLNT/FLOODRAPIDGOTO/-2.00000,19.00000,20.00000PT2RAPIDGOTO/-2.00000,19.00000,14.00000PT3FEDRAT/150.0000GOTO/-2.00000,19.00000,13.30000PT4GOTO/.00000,19.00000,13.30000PT5CUTTER/2.0,.3120,.6880,.3120,.0,.0,4.0FEDRAT/50.0GOTO/20.0,20.0,20.0PPRINT************************************************************PPRINTLOAD2"DIAFACEMILLWITH.312CORNERRADIUSPPRINT************************************************************LOADTL/230002.0,LENGTH,.0,OSETNO,1.0SPINDL/9963.0,CLWCOOLNT/FLOODRAPIDGOTO/-2.0,19.0,20.0RAPIDGOTO/-2.0,19.0,14.0FEDRAT/150.0GOTO/-2.0,19.0,13.30GOTO/.0,19.0,13.30FEDRAT/105.0GOTO/28.0,19.0,13.30FEDRAT/150.0GOTO/28.0,17.60,13.30APTSourceDataCLDataNCDataInterfaceCutterGeometryIdentificationCutterstatement:CUTTER/d,r,e,f,a,b,hdfehabrDifferentCutterShapesNCDataInterfaceCutterPath/PassesIdentificationDetectionofthestartingpointandendingpointofeachpath/sub-passes.Calculationofcutvolume.Basedoncuttercross-sectionandcuttermotion.Cutter-MeshIntersectionDetectionDetectionofelement-cutterintersection.InitialResidualStressInputMethodsavailableinMSC.Marc:NumericalDataInput(Pre-State)TransferofstressesfromendofpreviousmanufacturingsimulationtometalremovalsimulationusingPRE-STATE.Accurate:Fromint.pointtoint.point.ofthesameFEmesh.Userfriendly.InitialResidualStressInputPre-State:InitialResidualStressInputMethodsavailableinMSC.Marc(cont.)TextdatafileTransferofmeasurementdata(X-raydiffraction,etc.)tomodelviatextdata. ResidualStressdataintheworkpieceareautomaticallyextrapolatedtotheunderlyingmesh.InitialResidualStressInputTextdatafileInitialResidualStressInputMethodsavailableinMSC.Marc(cont.)Tabularformat

FESolutionTreatmentofIntersectedFiniteElementEntitiesFullyIntersectedFiniteElementsAutomaticallydeactivatedandStressesreleased.PartiallyIntersectedFiniteElementsSubdividedusingLocalAdaptiveRemeshing.Usersetslevelsofsub-divisiontobeused.Fullyintersectedchildelementsaredeactivated.FESolutionwithReducedNumberofElementsFESolutionAdaptiveRemeshingforMachiningFESolutionMachiningLoadcasedefinition

AdaptiveMeshing

ExampleHoleDrillingInitialFEMmodel:408brickelements,668nodesFinalFEMmodel:Onelevelsplitting:600:528elementsTwolevelsplitting:2328:1656elementsThreelevelsplitting:8472:5112elementsNote:redreferstotheactiveelements

Example:HoleDrillingAccuracyComparison

WithoutremeshingWith1levelremeshingabccutter

Example:HoleDrillingWith2levelsremeshingWith3levelsremeshingcSignificantimprovementofaccuracywithadaptiveremeshing

cutterExample:PocketCutting

CutsintheLowerSurface CutsintheUpperSurface MoreCutsintheUpperSurface

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