平压平模切机模切有限元分析及实验研究 320.docx

平压平模切机模切有限元分析及实验研究 320.docx

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平压平模切机模切有限元分析及实验研究320

Chineselibraryclassificationnumber:

TS803

TheResearchofFiniteElementAnalysisandExperimentonDieCuttingProcessinthePlatenDie-cuttingMachine

Abstract：

Theresearchobjectisthedie-cuttingequipment,thedie-cuttingpressureproductionmechanismandinfluencefactorswerestudiedindepth.Themethodofcombiningthediecuttingprocesscomponents'finiteelementanalysiswithexperimentisproposed.Thedeformationforthedie-cuttingprocesspartsincludingcardboard,bladelineandspongerubberstripwasanalyzedbyfiniteelementmethod,andthemechanicalcharacteristicsofvariouscomponentswereobtained.Thedie-cuttingpressuretestworkbenchdevelopedinBIGCdigitalmanufacturinglaboratoryadoptspneumaticandhydraulicdrivensystemanddeterminesthediecuttingpressurethroughtheoilpressurevalue,therelationshipbetweenthediecuttingpressureandprocesscomponentsparametersisobtainedbyexperimentalanalysis.Comparingthesimulationresultswiththeexperimentalresults,itisprovedthatthesimulationresultscanrevealtherealdiecuttingpressurevaluebasically,butitstillneedfurtheranalysistogetthesubtlefactorsthataffectdiecuttingpressuretoimprovetheaccuracyofthesimulation.

KeyWords：

die-cuttingmachine;finiteelementmethod;pneumaticandhydraulicdrivensystem;nonlinearity;experiment

0Introduction

Inprintingandpackagingindustry,printingmachine,die-cuttingmachine,laminatingmachine,etc,asacomplicatedequipment,theirkeymechanismsaredesignedwithaninnovationmethodofvirtualprototypegradually,theyarerelativelycomplexinbothstructureandoperationprocess,so,tothemodelmachine,dynamicsimulationsoftwareisappliedtoanalyzetheirstatics,kinematicsanddynamics,thenoutputdisplacement,velocity,accelerationandtheanalysisresultsofreactioncurve,scopeofpredictionmechanismmotion,collisiondetection,peakloadandfiniteelementcalculationinputload[1][2]toshortenproductdevelopmentcycle,reducethecost.Forthewholeindentingprocessinthediecutting,pressurecontrolisakeypointintheprocessofqualitycontrol.Duetothediecuttingtoolsandcuttingpressurebythepressureonthematerialphysicalpropertiesanddifferentdie-cuttingversionoftheperformanceimpactcannotbeneglected,theinitialsettingpressureisdifficulttoset.Asareference,thediecuttingpressurecanbeobtainedbyusingthemethodoftheoreticalcalculation,butinactualproduction,influencedbyvariousfactors,anon-ignorabledeviationexistsbetweenthetheoreticalvalueandpracticalvalue.Duringtheactualproductioninthefactory,italwaystakesatestmethodtodeterminetheshearingforcevalueonunitlength,andthencalculatethesizeofthediecuttingpressure,theprocesscan'timprovetheproductionefficiency,andhascertainconsumptiononmanpowerandmaterialresourcesatthesametime.Thispaperpresentsamethodcombiningthediecuttingprocesscomponents'finiteelementanalysiswithexperiment,analysisofmechanicalcharacteristicsforcardboard,bladelineandspongerubberstripunderdifferentworkingconditionsrespectively,thesimulationresultswillbecomparedwiththeexperimentalresults,byafurtheroptimizationoffiniteelementanalysismethodswiththeresults,themechanismofdiecuttingpressurewillberefined.Themethodhasaguidingsignificanceinreplacingactualproductiontestmethodbyfiniteelementdiecuttingpressuresimulationmethod,improvingtheproductionefficiencyandreducingproductioncost.

1thetheoreticalbasis

1.1die-cuttingcreasingmechanismanalysis

Drivenbythepressuremechanism,thelowerplatformofdiecuttingmechanismmovesupandbumpsintotheupperplatform,deformationwillbeproducedonthecardboardplacedonthelowerplatformbythemouldpressingoftheindentationlineandtheupperbladeline,theelasticdeformationstagecomesfirst,thatis,printmaterialssuchaspaper,thefiberandpackinginthecardboard,etc.willhaveelasticdeformation,andthenenterthestageofformationdamagewiththeincreaseofindentationprocessingpressure,atthistime,theincreasingstressconcentrationnearthesteelbladeandsteellinemakesthelocaldestructionofinternalfiberandpackingpaper,leadingtotheprintingqualityonthesurfaceorcardboardindentation.Fordiecutting,thedeformationdoesnotendsofar,butwiththefurtherincreasingpressure,itentersthenextstageofbrittlefailurephase,orcallsthecutoffstage,andwillcutoffthecertainpartsofthecardboardorprint;aftercutoffthecardboard,bladecollisionwithsteelplateundertheplatformandproducetinydeformation[3].Themainpartsoftheprocessincludesupperandlowerplatform,pressurecuttinginstitutionsandtemplates,templatesincludeindentationbottomdieandbottomdiesteel,whichplacedonthelowerplatform.Pressurecuttinginstitutionsincludediecutterbaseboard,blade,indentationsteelline,andspongestrip,whichplacedontheupperplatform.

Theworkresistanceofthediecuttingwork,mainlyfromthreeaspects,ontheonehand,withtheincreasingofmouldpressing,thedeformationofelasticstripincreases,theresistancecomesfromtheelasticreactionofthedeformedstrip;Thesecondaspect,intheprocessofloading,theresistancecomesfromtheprocessingthatindentationlinemadeplasticindentationonthecardboard;Thethirdaspectisintheloadedprocess,theresistanceonthediecuttingbladecuttingcardboardandthepressureontheplatformdeformationwhendiecuttingbladehascutthroughthecardboard.Thediecuttingpressureisthetotalresistancesfromthethreeaspectsinthediepressingprocess.

Studyingthetheoryofdiecuttingstressishelpfultogetinformationsuchastheprocessmodelcharacteristics,physicalcharacteristics,deformationanddynamicprocessmodeling,laytheoreticalbasisforthefiniteelementsolution.

1.2thefiniteelementmethod

Cutterlineresistanceandstripelasticreactionaretwoimportantfactorsofdiecuttingpressure,inordertoanalysisthemechanismthatisproducedbydiecuttingpressurein-depth,itisnecessarytoanalyzethedeformationoftheknifelineandthestrip.Thediecuttingmodelofthecomponentsincludesbothcharacteristics,physicalcharacteristics,andprocesscondition,thestressdataisusedtodescribeprocessstate.IntheANSYSfiniteelementanalysissoftware,LS-DYNAisalargenonlineardynamicanalysisprogrambasedonexplicit,itcansimulateallkindsofcomplicatedgeometricalnonlinearityintherealworld（largedisplacement,largerotationandlargestrain）,materialnonlinearandcontactnonlinearproblem,especiallysuitableforsolvingallkindsofnonlineardynamicimpactproblemsuchashigh-speedcollision,explodeandmetalformingintwo-dimensionalorthree-dimensionalnonlinearstructure.Forexample,StanislawKutandFelikesStachowiczestablishesthefiniteelementmodelfor2.0~4.0mmsheetsteelusingthetheoryofelastic-plasticstrength4continuity,assumedtobeisotropicmaterials,numericalsimulationanalysisdrawaconclusionthatbendinginadvanceofsemi-finishedproductsisadvantageoustothesteelplatecuttingquality[4].Diecuttingindentationprocessisahigh-speedcollisionandstampingformingprocess,thebladecutthecardboard,indentationlinecreasingtheboard,sothemoldingprocesscanbesimulatedbyLS-DYNA,andusingexplicit-implicitsequencetosolve.

LS-DYNAgivesprioritytoLagrangealgorithm,includingtheALEandEuleralgorithmmeanwhile,itgivesprioritytononlineardynamicanalysisandhasstaticanalysiscapabilitiesatthesametime,itgivesprioritytoanexplicitsolutionandpossessesimplicitsolvingfunction[5].

Implicitalgorithm

LS-DYNAimplicittimeintegrationdoesn’tconsidertheinertiaeffect（[C]and[M]）,itcalculatesaverageaccelerationanddisplacementatthetimet+△t:

{ut+△t}=[K]-1{}（1-1）

Tothelinearproblemwhen[K]islinear,unconditionalstability;largetimestepcanbeadopted.Forthenonlinearproblem,thesolutioncanbemadethroughaseriesoflinearapproximation（Newton-Raphson）;requestingtransposednonlinearstiffnessmatrix[K];convergenceneedsmalltimestep;itcannotguaranteeconvergencetothehighlynonlinearproblem.

Explicitalgorithm

LS-DYNAexplicittimeintegrationusingthecentraldifferencemethodintimetotheacceleration:

{at}=[M]-1（[]-[]）（1-2）

Intheformula,istheexternalforceandphysicalvector,istheinternalforcevector,itconsistsoftheformula:

Fint=（1-3）

3itemsoftheformulainsequencearethecurrentunitstressfieldequivalentnodalforce,thesandglassresistance（toovercometheproblemofthehourglasssingle-pointgaussintegralandintroductionofviscousresistance）andthecontactforcevector.Speedanddisplacementofthenodecanbeachievedbytheformula:

{vt+△t/2}={vt-△t/2}+{at}△tt（1-4）

{ut+△t}={vt}+{vt+△t/2}△tt+△t/2（1-5）

Intheformula△tt+△t/2=0.5（△tt+△tt+△t），△tt-△t/2=0.5（△tt-△tt+△t）；Newgeometricconfigurationsobtainedbyinitialconfigurationplusdisplacementincrement,namely:

{xt+△t}={x0}+{ut+△t}（1-6）

Inthispaper,explicitdynamicmoduleinANSYSWorkbench—ExplicitDynamics（ANSYS）,andthetransientdynamicmodule（TransientStructural）areusedtoanalyzethedeformationofpapers,cutterlines,andspongestrips.Theelasticdeformationofthecardboardcanbeignored,andthematerialcanberegardedasarigid-plasticbody[6],therelationshipbetweentheelasticzoneandtheplasticareaneedn'ttobeconsidered,rigid-plasticfiniteelementanalysisisadoptedintheprocess.Bladelineandsteelplate’scollisionprocesscanbesim