外文翻译--A320机翼盘区使用的水平铆钉注射器的设计 英文版.pdf

PaperNumber2007-01-3783HorizontalRivetInjectorDesignUsedonA320UpperPanelChristopherBuchheit,PeterZieveElectroimpact,IncCopyright2007SAEInternationalABSTRACTThispaperwillcoverthedesignofthehorizontalrivetinjectoruseontheSA2LVERdesignatedforstage0productionofAirbusA320UpperWingPanels.TheinjectordesignisintendedtodecreasecycletimesandincreasereliabilitywhilenotreducingthefunctionalityoverpreviousrivetfeeddesignsusedbyElectroimpact.Specificrivethandlingmethodsanddesignfeatureswillbereviewedandtheirresultoncycletimeandreliabilitydiscussed.INTRODUCTIONTheSA2machineisthelatestintheLowVoltageElectromagnetRiveterfamilyorLVER.ThisfamilyisaseriesofwingpanelfasteningmachinesdesignedhasbeenimplementedforproductionoftheAirbusA320throughA380wingskinpanels.ThenewlyimplementedSA2machineincorporatesmanymajordesignrevisionsintendedtoincreaseproductivityandreliability.Oneofthesemajorrevisionsinvolvesthespecificprocessusedtomovetherivetslugfromthefeedtubetothepanel.Thispaperwillreviewthespecificsoftherivetinjectorithasimprovedbothreliabilityoftherivetingprocessandincreasedproductivitybydecreasingcycletimes.BACKGROUNDLVERBASICSSomedetailsonhowtheelectroimpactfasteningmachineworkswillbenecessaryinunderstandingthebenefitsofthenewinjectoroverthepreviousdesign.TheLVERisafamilyofpurposebuilt5-axismachinesdesignedtoaccuratelyfastenaverticallyorientedwingskinandstringer.(seeFigure1)TheLVERsuseapairofactuatedfasteningtablesthatdriveforwardtorigidlyclampthewingandstingertogetherbetweentwoclampingfeetsosubsequentdrillingandfasteningcanbecarriedoutwithoutdefectsbetweenthestringerandwingpanel.Theskinsidefasteningtablecarriesthemajorityoftheworktoolswhicharecarriedonamovableaxisallowingthetransfer(orshuttle)betweentoolswhileremainingclamped.Hereisadescriptionoftherivetfasteningcycle.ClampupandmeasurethestackthicknessShuttletodrillspindledrillholeShuttletoEMRInsertrivet,checkrivetlengthandformrivetShuttletoshavespindleShaveskinsiderivetheadflushtopanelUnclampandmovetonextfastenerpositionPREVIOUSRIVETGRIPPERPreviousdesignsfortransferringtherivetfromthefeedtubestothepanelhaveutilizedapneumaticgripperlocatedonthefrontoftheEMR.InadditiontherivetfeedpathincludedaFigure1:TheSA2machineintheAirbusfactoryinBroughton,UKNov.2006showingtheverticalorientationofthewingskinFigure3:DiagramofthemajorcomponentscomprisingtherivetinjectordropdownchutecalledtheU-turnwhichwaslocatedonthesideoftheclampingfoot.Thischuteonlylineduptotherivetgripperwhiletheshuttletablewasatthedrillposition.Thisoftenresultedinadelayinthecyclewherethedrillhadcompleteddrillingtheholebuttherivethadyettoreachtherivetgripper.Thisdelaywasespeciallyapparentinthinstacksandsmalldiameterrivetswheredrilltimewasatitsminimum.THESOLUTIONANEWRIVETINJECTORThenewinjectordesignsolutionwouldincorporateareductionofthefrequencyofadjustmentsandtheeliminationofdelaysinthecycleduetoafixedfeedpositionaswellasnotremovinganyfunctionalityfromtheoriginaldesigns.Firstthesolutiontothefixedfeedpositionrequiredthenewsystemtobelocatedonthemovingportionoftheshuttletable.Second,theadjustmentswouldbeeliminatedwithabuilt-inorpassivealignmentfeatures.Theoutcomeofthedesignprocesswasreplacingthepneumaticgripperwithasimplespringloadedrivetfingers,andreplacingtheU-turnwithanewrivetinjector.Theinjectorsjobistotransfertherivetfromthefeedtubestotherivetfingers.Therivetfingersreplacedthepneumaticgripperfrompreviousmachinesandareverysimilartodesignsusedonotherfasteningmachines.Theonlychangeisthatthefingersholdarivethorizontalinsteadofvertical.ThepurposeoftherivetfingersaresimplytoholdarivetdirectlyinfrontoftherivetdiesowhentheEMRdrivestowardthepanel,therivetisinsertedintothepreparedhole.TheentiredevicehasnopneumaticsorelectronicsandonlyreliesonspringstoholdtherivetandsimpleslotscutintotheEMRdriverforalignment.TherewaslittledesigneffortputintothisassemblyonlyamatteroffittingittotheexistinghardwareontheendoftheEMRdriverbearing.Themajorityofthedesignwentintothenewrivetinjectorwhichhadtofeedahorizontalrivetintotherivetfingers.TherivetinjectorispositionedinaspaceunderneaththeEMRbutabovethesealantinserter.TheItalsohadtobebehindtheclampingfootbutfarenoughforwardtominimizethetraveloftheEMRwhichalsoimpactedcycletimes.(seeFigure2withtheInjectorastheblueandblackrectangleLeftofcenter,thesealantinserterthelongblackrectangleatananglebelowcenterandtheclampingfootthesilvershapetouchingthewingpaneljustabovecenter)ThedecisionwastohangtheinjectorunderneaththeEMRbyapairofsupportlegswhichreacharoundtheoutsideoftheEMRanddowntotheinjector.(seeFigure3)Thereforetheinjectormoveswiththeshuttletableaxisbuthasafixedzaxis(towardandawayfromthewingpanel)positionontheEMR.Whenitcomestimetofeedarivet,theEMRmovestothefeedpositiononitsZaxisandwaitsfortheinjectortoplacearivetintherivetfingers.Thefeedtubesblowtherivettoachamberintheinjectorlocatedabout75mmbelowtherivetfingers.ThislocationisashighaspossibleyetstillallowingtheEMRtopassoverthetopduringtheformingprocess.ThischamberisjustslightlyFigure2:Theskinsideprocesstoolsandclampingfoot.Therivetinjectoristhebluerectangleleftofcenter.Figure4:Diagramoftherivetchambershowingtherivetgripedbetweenthestoppinandgripbarlargerthenthe1/4rivetandiscompletelyenclosedatthistimebythecover.Next,theentranceofthechamberisblockedoffwithapop-upstopperpin.Oncethestopperpinisextended,thenthegripbarwouldpinchtherivetaxiallybetweenthestopperpinandthegripbar.(seeFigure4)Nowthattherivetiscaptured,thecoverretractsleavingthechamberopenfromthetopandtwosides.Next,thetowerextends,translatingtherivettherequired75mmtotherivetfingers.(seeFigure5)Oncethere,thespringloadedrivetfingersgriptherivetontwosides.Nowthegripbarandstopperpinretractandthetowerlowers,leavingtherivetinthefingersreadytobefedintothewingpanel.Thewholeprocesstakesabout0.92secondsandcanbedonewhiletheshuttletableismovingsothereisnolongeradelayintherivetcycle.DESIGNFEATURESAxialRivetGrippingOneofthemajordesignaspectsoftherivetinjectoristheaxialgrippingoftherivet.Thisfeatureactuallyhelpstoeliminatenearlyallofthealignmentrequirementsbetweentheinjectorandrivetfingerbyallowingsomeflexibilityandtolerancetomisalignment.Ifboththeinjectorandfingersheldtherivetonthesides,therivetwouldbeoverconstrainedduringthetransfer.Thiswouldrequireatightalignmentbetweenthetwoassemblies.Grippingtheendsoftherivetreleasesthisoverconstrainingproblem.Itispossiblethataloosealignmentwouldcausetherivettobemishandledwhereitwoulddroporcausedtobetippedinthefingers.Inadditiontheaxialgrippingalsopushestherivettowardtherivetdiesettingafixeddistancefromtherivetdietotheendoftherivet.Thisisopposedtosettingthefixeddistanceonthepanelsideoftherivet.Puttingthesetdistanceonthediesidereducesthelengthofthefingerssincewealwaysknowwheretheendoftherivetwillbelocated.Inaddition,thisreducesthechanceofmarkingtheshankoftherivetbecausethefingersdontneedtoslidedownthelengthoftherivetbeforecontactingtherivetdie.PlasticOnlyContactSpecialconsiderationshavebeengiventorivetmarkingwiththenewrivetinjector.Toreducecycletimestherivetisblownthroughthefeedtubsatveryhighspeeds.Atthesespeedswhenevertherivetcontactsametalsurface,asmallmarkontheendoftherivetisproduced.Thismarksimplyaremovaloftherivetcoating,morethenagougeorscratch,butthereissomeconcernwiththelongtermproblemsassociatedwithmarkedrivets.Thereforeanysurfacetherivetcancomeincontactwithismadeofplasticandarealleasilyreplaceable.AirVentsIntheprocessoftestingtherivetinjectorwediscoveredaneedtoincreasetheairflowthroughthefeedtubes.Therivetistransferreddownthefeedtubesusingcompressedair.IncreasingthespeedoftheairintheFeedtubesalsoincreasedthespeedofthetransferredrivet.Howevertherivettravelingathigherspeedbouncedofftheendoftherivetchamberfartherandfartherastheairspeedwasincreased.Theresultwasaincreaseincycletimesduetolongersettlingtimes.Tofixthisproblem,longventswerecutintotherivetchamber.ThissolutioncompletelystoppedallrivetFigure5:Diagramoftherivetinjectorintheraisedpositionbouncebacknomatterhowfasttherivetwastraveling,byallowinglargeamountsofairtopassaroundtherivetholdingitagainsttheendoftherivetchamber.DoubleRivetCheckOccasionallytworivetswindupinthefeedtubesatthesametime.Theresultisasituationwhereitisunknownwhichrivetisthecorrectforthepreparedhole.Acheckfortworivetsispreformedbythestopperwhenitextendstoblocktherivetchamber.Therivetchamberhasbeensizedtoonlyallowonrivetinthechamber.Bybeinglongerthanthelongestrivetbutshorterthan2timestheshortestrivet.Thatifmorethenonerivetwasfedthenthestopperpinwontbeabletoreachtheendofitstravel.Thistriggersanautomaticpurgecyclewheretherivetchamberisopenedup,alltherivetsareblownoutofthesystem,andanewrivetisfed.CONCLUSIONOneofthemajorgoalsoftheSA2projectwastodecreaserivetcycletimesoverpreviousmachin