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外文翻译--织机打纬机构的计算机辅助分析 英文版.pdf

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外文翻译--织机打纬机构的计算机辅助分析 英文版.pdf

http//trj.sagepub.com/TextileResearchJournalhttp//trj.sagepub.com/content/68/9/630TheonlineversionofthisarticlecanbefoundatDOI10.1177/004051759806800902199868630TextileResearchJournalYoujiangWangandHuiSunComputerAidedAnalysisofLoomBeatingupMechanismsPublishedbyhttp//www.sagepublications.comcanbefoundatTextileResearchJournalAdditionalservicesandinformationforhttp//trj.sagepub.com/cgi/alertsEmailAlertshttp//trj.sagepub.com/subscriptionsSubscriptionshttp//www.sagepub.com/journalsReprints.navReprintshttp//www.sagepub.com/journalsPermissions.navPermissionshttp//trj.sagepub.com/content/68/9/630.refs.htmlCitationsWhatisThisSep1,1998VersionofRecordtrj.sagepub.comDownloadedfrom630ComputerAidedAnalysisofLoomBeatingupMechanismsYOUJIANGWANGANDHUISUNSchoolofTextileFiberEngineering,GeorgiaInstituteofTechnology,Atlanta,Georgia30332,U.S.A.ABSTRACTAnalysisanddesignofthebeatingupmechanismisofgreatimportanceforimprovingloomperformance.Computeraideddesignandanalysistoolsareusedtostudydifferentkindsofbeatingupmechanisms,includingthe4linkand6linksystems,andtheircharacteristicsarecomparedwiththoseoftheconjugatecammechanism.Resultsfrommodelswithvaryinggeometricparametersarepresented,revealingthatthecomputertoolsareeffectiveandusefulinanalyzinganddesigningbeatingupmechanismswithsmootheroperation,lowernoiseandvibration,andhigherspeeds.Thelastdecadehaswitnessedthetransformationof,thetextileindustryfromalaborintensiveoneintoahighproductivity,capitalintensiveindustry.Inmanufacturingwovenfabrics,thereisaconstantdesireforhighperformanceloomsthatarefast,energyefficient,reliable,highlyautomated,quiet,durable,andlowmaintenance.Overthelastfewdecades,theproductionrateofloomshasincreasedtremendously,withmaximumweftinsertionratesmovingfromabout200.towellover2000m/min.Suchasignificantimprovementinperformanceisaresultoftechnologicalinnovationse.g.,shuttlelessweaving,employmentofnewtechnologiese.R.,computersandmaterials,andbettermachinerydesigns.Regardlessofthekindofloom,itstechnologicalstate,orthepatterntobewoven,thebasicweavingoperationsconsistsoffourstepsshedding,picking,beatingup,andtakingup/lettingoff2J.Theshed...dingoperationraisesandlowersspecificwarpyarnsbymeansofharnessestoformashed.Duringthepickingstep,thenewfillingyamisinsertedthroughtheshed..Beatingupoccurswhenthenewlyinsertedfillingyarnispushedfirmlyinplacebymeansofthereedmountedonthesley.Finally,thefinishedfabriciswoundontheclothbeam.whilemorewarpyarnisreleasedfromthewarpbeam.Thesefouroperationsareperformedina¡..constantlyrepeatedsequence.Beatingupisofgreatimportancetotheweavingprocessandthequalityoftheproduct.Anormalbeatingupoperationwillgiveafirm,uniformfabricstructure.Inaddition,themovementofthereedcarriedbythesley,throughwhichbeatingupisachieved,hasanimportanteffectonthe.smoothnessofsheddingandpickingoperations.Inhighspeedweaving,therelativetimepercycletakenbyoperationsotherthanpickingshouldbeminimized.Itisdesirablethatthereeddwellaslongaspossibleatthereartoleavemoretimeforweftinsertion,andthenmoveswittlytobeatupthenewfillingyarn.Thisisespeciallycrucialformodernwidewidthlooms.However,higherforcesandvibrationsareassociatedwithjerkymovements,anddesigncompromiseisnecessarytoachieveabalancebetweenloomspeedandsmoothoperation.Dynamicanalysisofthemotionofthesleyreedisthereforeimportantforloomdesignersandmanufacturers.Ingeneral,therearethreebasickindsofbeatingupmechanisms4link.6link,andconjugatecarn,asshowninFigure1.The4linkmechanismisusedmostwidelyonshuttle,airjet,andrapierlooms.sinceithasasimplestructureandiseasytomanufacture.The6linkmechanism,whichmayprovidealongerdwellperiod,ismainlyusedinairjetlooms.Theconjugatecammechanismisbeingusedmoreandmorewidelyinshuttlelessloomsduetoitspreciseandadjustabledwellperiodofthesley.Thedesignofbeatingupmechanism,particularlytheirmassdistributionandgeometry,hasasignificanteffectontheperformanceoftheloom.Traditionalmethodsforanalyzingthesemechanismsbasedonkinematicanddynamicprinciplesarewellestablished,butofteninvolvelengthymathematicalderivations.Computeraideddesignandanalysistoolsprovideasimplerwayofanalyzingthedynamicresponsesofcomplexstructures.WorkingModel,asoftwareproductofKnowledgeRevolution,Inc.11.combinesadvancedmotionsimulationtechnologywithsophisticatededitingabilitiestoprovideausefultoolforengineeringandanimationsimulation.Amechanismcanbeconvertedintoasetofrigidbodiesandconstraintstobuildthemodelonthecomputer.ThissoftwaresimulatesthemotionofthemechanismbasedongeometricconstraintsandNewtonianmechanics.principles.Quantitiesdefinedbeforethesimulationcanbeexportedduringthesimtrj.sagepub.comDownloadedfrom631FIGURE1.Typicalbeatingupmechanismsa4link,b6J.ink.andcconjugatecamulatingprocessforfurtheranalysis.Thepropertiesofobjectscanbeadjustedwithitsgraphicuserinterfacetoformnewmodelswithdesirableresults.Inthisstudy,wefirstanalyzethe4linkmechanismusingtheWorkingModelsoftware.Aparametricstudyexplorestheeffectofgeometryonthesleysmotion.Wealsobuildmodelsforthe6linkmechanismtoidentifygeometricconfigurationsthatcanleadtoalonginsertionperiodinaweavingcycle.Finally,wecomparethesleysmotionfordifferentbeatingupmechanisms.BeatingupMechanismsFOURLINKMECHANISMFigure2showsthecomputermodelobtaineddafterimplementingallpartsofa4linkmechanismwithWorkingModel,accordingtotheactualsizemass,andconnectiontype.QuantitiesmeasuredandrecordedduringthesimulationincludethedisplacementofthesleyX,thevelocityofsleyV,theaccelerationofsleyA,andtheforceFactingontheswordpin.TovalidateWorkingModel,wehavecomparedtheresultsfromtheWorkingModelsimulationandkinematicsanalysisandfoundnonoticeabledifferences.Forparametricstudies,wehaveusedtheactualdimensionsofmachinepartsinashuttleloomFigureIacrankshaftlengthr6cm,connectingrodlengths32cm,andsleylengthL72.11cm.Thisgeometricconfigurationisthereferencefortheperformancecomparisonwithothermodels.Wehaveassumedthattheloomspeedis200rpm.Toobservetheinfluenceofdifferentratiosofslronthemotionofthesley,theconnectingrodlengthvariesfrom17to102cm,whilerandLarekeptconstant.Wehaveevaluatedelevemmodelswiths/rratiosfrom2.83to17.FIGURE2.Computermodelof4linkbeatingupmechanism.FromtheWorkingModelsimulationdata,wehaveobtainedthemaximumvaluesofsleyvelocityV,accelerationA,andtheforceintheconnectingrodF,foreachmodel.TheresultsareshowninFigure3,normalizedwithrespecttothereferencemodel.Becauses/rvariesfrom2to8,themaximumvaluesofV,A.andFdecreasesignificantly.However.thereislittlechangeinVmax,Amj,,andFmaxasslrincreasesfurther.Toensuresmoothfillingyaminsertionthroughtheshed,theshedshouldbekeptlargeenoughduringthefillingtraverse.Thesizeoftheshedisdeterminedbytheheightbetweenthetwosheetsofyamsandthepotrj.sagepub.comDownloadedfrom632FIGURE3.Effectofgeometricratio.s/ronsleysmotioncharacteristics.sitionofthesley.Duringaweavingcycle,thefillingyamcanonlybeinsertedwhenthesleystayscloseto.thebackwardpositionandtheshedopeningissufficient.Thus,forfastloomoperation,thesleyshouldstaybackwardmostofthetimeforfillinginsertion,andthenmoverapidlyforbeatingup.Theexactrangeofsleypositionsallowingfillinginsertiondependsontheparticulardesignofaloom.Inthisanalysis,wehaveassumedthatthefillinginsertioniscompletedduringtheperiodwhenthesleyisinthedquobackzonedquobetweenitsoriginalmostbackwardpositionandonehalfof.itsmaximumdisplacementFigure4.Thecorre..spondingperiodisreferedtoastheinsertionperiod.Fromthesimulationdataonthedisplacementofthe.sley.,weseethatthesleyreachesonehalfitsmaximum.displacementatdifferentdegreesofthecrankrotation,dependingonthegeometryofthe4linkmechanism,.assummarizedinTableI.Withincreaseds/r,thesleystaysnearitsmostbackwardpositionforashorterFIGURE4.Effectofgeometricratiosironthedisplacementprofileofthesley.TABLE1.Insertionperiodsfordifferent4linkmodels.amountoftime,leavinglesstimeforthefillingtobeinsertedacrosstheloom.Nomatterwhatmechanismisdiscussed,alowerAmaxindicatesasmoothermovementandahigherA,,,,,,leadstoajerkyaction.Foraloominparticular,themovementofthesleyaffectstheefficiencyofbeatingup.Fordifferentfabrics,however,differentactionsofbeatinguparedesired2.Afine,delicatefabricshouldnotbehandledroughly,whereasacoarsestapleyammayrequiresharpbeatinguptobeeffective.Therefore,forlightfabricssuchassilkandfinecotton,onlyverygentlebeatingupisrequiredandalargeslivalueissuitablee.g.,6.Formediumfabricssuchasmediumdensitycotton,asmoothbeatupisneeded,andtheslrratioshouldbemediume.g.,between3and6.Forheavyfabricssuchasjeansorindustrialmaterials,animpulsive,jerkysortofbeatupisnecessary,andasmallslrratioismoreappropriatee.g.,3.Forawideloom,whichneedsalongtimeforthefillingtobeinserted,alowerslrratioshouldbechosen.Incontrast,ahigherslrratioissufficientforanarrowloom,whichrequiresashorttimeforfillinginsertion.TheperformancemapshowninFigure5isobtainedbycombiningtheeffectsofthegeometric.s/rratioonthesleysmotionandinsertionperiod.Thehorizontalaxisisthemaximumforceactingonthepinjointoftheconnectingrodandthesley.Thelongitudinalaxistrj.sagepub.comDownloadedfrom

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