AA7075铝合金接头的无模紧固工艺和接合强度【字数9800字】
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上传时间：2018-04-23
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- 关 键 词：
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aa7075
铝合金
接头
紧固
工艺
以及
接合
强度
字数
- 资源描述：
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AA7075铝合金接头的无模紧固工艺和接合强度【字数9800字】,aa7075,铝合金,接头,紧固,工艺,以及,接合,强度,字数
- 内容简介：
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THINWALLEDSTRUCTURES1202017421431DIELESSCLINCHINGPROCESSANDJOINTSTRENGTHOFAA7075ALUMINUMJOINTSMOSTAFAKSABRAATIA,MUKESHKJAINDEPARTMENTOFMECHANICALENGINEERING,MCMASTERUNIVERSITY,HAMILTON,ONTARIO,CANADAL8S4L7ARTICLEINFOKEYWORDSDIELESSCLINCHINGAA7075ALUMINUMTEMPERMATERIALOWABSTRACTAA7075ALUMINUMALLOYSHEETSINDIERENTTEMPERCONDITIONSO,WANDT6WEREJOINEDBYDIELESSCLINCHINGTHEMATERIALOWBEHAVIOR,NECKTHICKNESSANDINTERLOCKCHARACTERISTICSDURINGCLINCHINGWEREINVESTIGATEDBYMETALLOGRAPHICOBSERVATIONSOFCLINCHED,CUTANDMOUNTEDSAMPLESBLANKHOLDERSOFDIERENTSHAPESANDDIMENSIONSWEREUSEDTOCONTROLTHEMATERIALOWTHEEECTSOFBLANKHOLDERGEOMETRICPARAMETERSASWELLASFORMINGFORCESONTHESHAPEOFTHEFORMEDINTERLOCKINCLINCHINGWERESTUDIEDTHEHIGHESTSTRENGTHTEMPERSTATET6WASSHOWNTOPOSSESSPOORCLINCHABILITYASITFAILEDTOCLINCHUNDERMOSTCLINCHINGCONDITIONSTHISWASATTRIBUTEDTOITSPOORDUCTILITYANDFORMABILITYATROOMTEMPERATURECOMPAREDTOTHEOTHERTEMPERSLASTLY,MECHANICALPERFORMANCEOFTHEFORMEDJOINTSWASCHARACTERIZEDBYCONDUCTINGSINGLESHEARLAPASWELLASPEELTESTSVARIOUSFAILUREMODESWEREOBSERVEDFORTHEDIERENTCLINCHINGCONDITIONSANDMATERIALTEMPERSTATES1INTRODUCTIONVEHICLEWEIGHTREDUCTION,INCREASEDFUELECONOMY,ANDINCREASEDSAFETYOFTHESTRUCTURESINTRANSPORTATIONAPPLICATIONSHASLEDTOMUCHINTERESTINLIGHTWEIGHTHIGHERSTRENGTHSTRUCTURALALUMINUMALLOYS1,2SUITABLEJOININGTECHNIQUESTOCREATESUCHSTRUCTURESWITHALUMINUMSHEETSAREREQUIRED1GENERALLY,SIMILARANDDISSIMILARSHEETMETALSCANBEJOINEDBYADHESIVEBONDING,WELDING,ANDMECHANICALFASTENING3,4DICULTYOFWELDINGHIGHSTRENGTHALUMINUMSHEETSANDLONGTIMESFORADHESIVEBONDINGMAKEMECHANICALFASTENINGAPROCESSOFMUCHINTERESTFORJOININGOFHIGHSTRENGTHALUMINUMSHEETS5AMONGTHEDIERENTMECHANICALFASTENINGTECHNIQUESAVAILABLEINMANUFACTURING,CLINCHINGISACOMMONMETHODOFJOININGBYFORMINGINWHICHTWOORMORESHEETMETALSARELOCALLYDEFORMEDUSINGPUNCHANDDIETOFORMAGEOMETRICALINTERLOCK68ASSHOWNINFIG1CLINCHINGENABLESJOININGOFTWOORMORESIMILARORDISSIMILARSHEETMATERIALSWHEREINDIVIDUALTHICKNESSCANVARYFROM04TO4MM9ACLINCHEDJOINTISFORMEDENTIRELYBYTHEGEOMETRICINTERLOCKALONEANDWITHOUTADDINGANYADDITIONALPHYSICALCOMPONENTTOTHEJOINTAHIGHTHROUGHPUT,LOWCOST,CLEANANDENVIRONMENTALLYFRIENDLYMANUFACTURINGENVIRONMENTOFTHECLINCHINGPROCESSARISESFROMNOHARMFULLIGHT,HEATORSMOKEEMISSIONSLASTLY,CLINCHINGOERSAHIGHTOOLLIFECOMPAREDWITHTHEOTHERJOININGTECHNIQUES4THEMAINGEOMETRICPARAMETERSTHATAECTJOINTSTRENGTHARENECKTHICKNESS“N”ANDINTERLOCKDEPTH“U”10,ASSHOWNINFIG1CLINCHEDSTRUCTURESCANWITHSTANDLOADSINSHEARANDAXIALMODES11THESHEARSTRENGTHOFACLINCHEDJOINTISCOMPARATIVELYHIGHERTHANITSAXIALSTRENGTH11INGENERAL,CLINCHINGRESULTSINLOWERJOINTSTRENGTHCOMPAREDTORIVETINGWHICHCANLIMITITSUSEINCERTAINHIGHSTRENGTHAPPLICATIONS12THEMAINLIMITATIONOFUSINGTHECONVENTIONALCLINCHINGTECHNIQUEISTHATTHEPROCESSINTRODUCESSURFACESTEPSONBOTHSURFACESOFTHEJOINEDSHEETSWHEREONESIDECONSISTSOFAPROTRUSIONANDTHEOTHERAPITEORTHASBEENMADETOREDUCETHEPROTRUSIONHEIGHTBYRESHAPINGTHECONVENTIONALCLINCHEDJOINT1315COUNTERMEASURETOOLINGHASBEENUSEDINTHISREGARDBYTONGETAL16THESTUDYSHOWEDAREDUCTIONOF50INPROTRUSIONHEIGHTWITHOUTAECTINGTHEJOINTSTRENGTHFRANCESCOETAL17UTILIZEDTWOSTEPSCLINCHINGTOJOINALUMINUMANDACARBONBERREINFORCEDPOLYMERCFRPWHERETHERSTSTEPINCLUDEDCONVENTIONALCLINCHINGBYUSINGEXTENSIBLEDIESWHILETHESECONDWASARESHAPINGSTEPUSINGPUNCHANDATDIEASSHOWNINFIG2THEMAINDISADVANTAGEFORTHISAPPROACHISTHEDICULTYOFALIGNINGTHEATTENINGPUNCHWITHTHEPREFORMEDJOINTBORSELLINOETAL6PROPOSEDASOLUTIONCONSISTINGOFATTENINGOFTHEPREFORMEDJOINTUSINGTWOATANVILSINADDITIONTOELIMINATINGTHEPROTRUSIONHEIGHT,THEATTENEDCLINCHEDJOINTWASALSOFOUNDTOWITHSTANDHIGHERLOADSTHANTHECONVENTIONALCLINCHEDJOINTSCHENETALUSEDAPAIROFATDIESWITHORWITHOUTARIVETTOREDUCETHEPROTRUSIONHEIGHTOFCONVENTIONALCLINCHEDJOINTPRODUCEDBYEXTENSIBLEDIES18,19ALLOFTHEABOVERESHAPINGTECHNIQUESSUERFROMINCREASEDCYCLETIMEDUETOTHEADDITIONALSTEPTHATINVOLVESADIERENTTOOLSETTOMAKECLINCHINGMOREAESTHETICALLYAPPEALINGANEWAPPROACHCALLEDDIELESSCLINCHINGHASBEENDEVELOPEDINWHICHSURFACESTEPEXISTABBREVIATIONST6,ARTICIALPEAKAGEDSTATEWHICHREPRESENTSTHEHARDESTTEMPERWTEMPER,SOLUTIONHEATTREATEDSTATEOTEMPER,ANNEALEDTEMPERSTATEN,NECKTHICKNESSOFTHEJOINTU,INTERLOCKDEPTHOFTHEJOINTCORRESPONDINGAUTHOREMAILADDRESSATIAMMCMASTERCAMKSABRAATIAHTTP/DXDOIORG/101016/JTWS201706021RECEIVED21MARCH2017RECEIVEDINREVISEDFORM29MAY2017ACCEPTED19JUNE2017AVAILABLEONLINE27SEPTEMBER201702638231/2017ELSEVIERLTDALLRIGHTSRESERVEDCONTENTSLISTSAVAILABLEATSCIENCEDIRECTTHINWALLEDSTRUCTURESJOURNALHOMEPAGEWWWELSEVIERCOM/LOCATE/TWSMKSABRAATIA,MKJAINTHINWALLEDSTRUCTURES1202017421431422FIG1CROSSSECTIONOFACONVENTIONALCLINCHEDJOINTSHOWINGTHEGEOMETRYOFTHEJOINTANDDIERENTGEOMETRICPARAMETERSFIG2SHOWSTWOSTEPSCLINCHINGPROCESSTHERSTSTEPONTHELEFTSIDEISACONVENTIONALCLINCHINGPROCESSBYUSINGEXTENSIBLEDIETHESECONDSTEPONTHERIGHTSIDEISARESHAPINGPROCESSBYUSINGPUNCHANDATDIEADJUSTABLERINGWASUSEDTOADOPTTHEHEIGHTOFRESHAPINGFIG3ASCHEMATICOFCROSSSECTIONACROSSASINGLESTEPDIELESSCLINCHEDJOINTSHOWINGTHEMAINGEOMETRICPARAMETERSOFTHEJOINTONLYONONESIDE,OFTENONTHEUNEXPOSEDSIDEOFTHEJOINT20,21DIELESSCLINCHINGISAONESTEPPROCESSUSINGAPUNCHANDAATANVIL,ASSHOWNBELOWINFIG3THEDESIGNGROOVEINTHEBLANKHOLDERISAKEYFACTORINCONTROLLINGTHEMATERIALOWINORDERTOFORMTHEGEOMETRICINTERLOCKTHEUSEOFATANVILINONESTEPDIELESSCLINCHINGELIMINATESTHENEEDFORGOODALIGNMENTBETWEENTHEPUNCHANDTHEANVILASWELLASKEEPINGJOININGTIMEASSHORTTIMEASPOSSIBLENEUGEBAUERETAL22SHOWEDTHATAVERYSMALLPROTRUSIONISFORMEDINDIELESSCLINCHINGCOMPAREDTOTHECONVENTIONALCLINCHINGTHECOMBINEDMOVEMENTOFBLANKHOLDERANDPUNCHMAKESTHETOOLINGFORDIELESSCLINCHINGMORECOMPLEX16INGENERALCLINCHJOININGISAWELLACCEPTEDANDWIDELYUSEDPROCESSFORJOININGDUCTILESHEETMETALSTHEJOININGGREATLYDEPENDSONFORMATIONOFAPERMANENTINTERLOCKBYAPPLICATIONOFPLASTICWORK23INRECENTYEARS,MUCHEORTHASBEENMADETOEXTENDCLINCHINGPROCESSTOJOINHIGHERSTRENGTHANDLOWERDUCTILITYSHEETMATERIALSLAMBIASEETALHAVEUTILIZEDAHEATERGUNTOLOCALLYINCREASEDUCTILITYOFAA6082T6SHEETSFORJOININGUSINGCONVENTIONALCLINCHING2426XIAOCONGETAL27HAVEPREHEATEDTHESHEETMETALBYUSINGOXYACETYLENEAMEGUNINORDERTOPERFORMCONVENTIONALCLINCHESONTA1TITANIUMSHEETSABEETAL28HAVEUSEDACOUNTERPRESSUREOFARUBBERRINGTOCONVENTIONALLYCLINCHULTRAHIGHSTRENGTHSTEELSHEETSNEUGEBAUERETAL20HAVETAKENTHEADVANTAGEOFUSINGATANVILINTHEDIELESSCLINCHINGPROCESSTOHEATTHEREDUCEDDUCTILEMAGNESIUMSHEETMETALFROMUNDERNEATHTHEANVILUSINGCARTRIDGEHEATINGTHREEFAILUREMODESAREGENERALLYENCOUNTEREDINPERFORMANCETESTINGOFCLINCHEDJOINTS29THESEINCLUDEIBUTTONFAILUREDUETOPLASTICDEFORMATIONONTHEFORMEDINTERLOCK,IIUNBUTTONINGFAILUREDUETONECKFRACTURE,ANDIIICOMBINEDFAILUREDUETOCOMBINATIONOFPLASTICDEFORMATIONANDNECKFRACTUREPRESENTWORKPRESENTSANEWSIMPLETOOLDESIGNFORDIELESSCLINCHINGPROCESSFORJOININGTWOSIMILARSHEETMETALSASWELLASAPARAMETRICSTUDYOFTHENEWTOOLINTERMSOFLOADVERSUSDISPLACEMENTCHARACTERISTICSDURINGTHECLINCHINGPROCESSTHEMATERIALOWANDJOINTINTERLOCKCHARACTERISTICSINDIERENTTEMPERSTATESHAVEBEENINVESTIGATEDBYOBSERVINGTHECUTCROSSSECTIONSOFTHEJOINTSWITHOPTICALMICROSCOPEINADDITION,SHEARANDAXIALSTRENGTHSANDFAILURESMODESOFTHEJOINTHAVEBEENASSESSEDBYUSINGSINGLESHEARANDPEELTESTS2MATERIALANDEXPERIMENTALPROCEDURE21MATERIALONESTEPDIELESSCLINCHJOINTSWEREPERFORMEDON127MMTHICKNESSSHEETSMADEOF7075ALUMINUMALLOYTHESHEETSWEREINITIALLYINT6TEMPER,APEAKAGEDCONDITIONTHATYIELDSTHEHARDESTSTATEORTHELARGESTULTIMATETENSILESTRENGTHTWOMORETEMPERSWERESUBSEQUENTLYOBTAINEDBYANNEALING,APARTIALLYANNEALEDSTATEAT413CFOR1HO1TEMPERANDAFULLYANNEALEDSTATEAT413CFOR3HO2TEMPERLASTLY,ANOTHERHEATTREATMENTWASCARRIEDOUTAT480CFOR3HFOLLOWEDBYWATERQUENCHINGTOOBTAINTHESOLUTIONHEATTREATEDMETASTABLESTATEWTEMPERALSO,MECHANICALPROPERTIESATEACHTEMPERSTATEWEREOBTAINEDBYCONDUCTINGTENSILETESTACCORDINGASTMSTANDARDE8/E8MUSINGANINSTRONUNIVERSALTESTINGMACHINEATACROSSHEADSPEEDOF1MM/MINSEETABLE1INORDERTOSAVEUSEDMATERIAL,SUBSIZESAMPLETABLE1MECHANICALPROPERTIESOFAA7075ALUMINUMALLOYATDIERENTTEMPERSTATESNOTEMPERMECHANICALPROPERTIESDESIGNATIONSYMBOLDESCRIPTION02YIELDSTRENGTHMPAULTIMATESTRENGTH,ULTMPAMAXELONGATIONKMPAN1T6ASRECEIVED620695129769011022WSOLUTIONTREATED230434258234028523OO1PARTIALLYANNEALED175295154859020714OO2FULLYANNEALED13524517428702141MKSABRAATIA,MKJAINTHINWALLEDSTRUCTURES1202017421431423FIG4ADRAWINGFORTHESUBSIZESHEETTENSILETESTSPECIMENASPERASTMSTANDARDE8OFDIMENSION120MMLENGTH6MMWIDTHWASUSEDACCORDINGTOASTMSTANDARDE8/E8MASSHOWNINFIG422DIELESSCLINCHINGPROCESSDIELESSCLINCHESWEREPERFORMEDBYUSINGATOOLSETMOUNTEDONA100KNSERVOHYDRAULIC,COMPUTERCONTROLLED,INSTRONTENSILETESTMACHINEATAPUNCHSPEEDOF30MM/STHETOOLSETCONSISTINGOFVARIOUSADAPTABLECOMPONENTSWASDESIGNEDTOSTUDYTHEMATERIALOWANDJOINABILITYOFTHESHEETMETALSUNDERVARIOUSPUNCHANDDIESETCONGURATIONSTHETOOLSETCONSISTEDOFPUNCH,ATANVIL,BLANKHOLDERSASWELLASCOMPRESSIONPOLYMERICSPRINGINORDERTOAPPLYABLANKHOLDINGFORCEASSHOWNINFIG5VARIOUSBLANKHOLDERSHAPESUTILIZEDINDIELESSCLINCHINGHAVEBEENREVIEWEDINREF1THEBLANKHOLDERSDIEREDINSHAPEANDDIMENSIONSASILLUSTRATEDINFIG6THEMATERIALOWWASEXPECTEDTOBEAECTEDBYTHEDIAMETERDOFTHEBLANKHOLDERGROOVETABLE2FIG6BLANKHOLDERSDESIGNSUTILIZEDINDIELESSCLINCHINGEXPERIMENTSBLANKHOLDERDESIGNPARAMETERSADDITIONALLY,THEGROOVEDEPTHTWASCONSIDEREDIMPORTANTININTERLOCKFORMATIONESPECIALLYATTHELATERSTAGEOFJOINTFORMATIONWHICHREQUIRESRESTRICTIONOFMATERIALOWINTHEAXIALDIRECTIONTOINCREASEINTERLOCKDEPTHASUMMARYOFTHEMAINBLANKHOLDERDESIGNPARAMETERSSTUDIEDINTHEPRESENTWORKISPROVIDEDINTABLE2THEBLANKHOLDERGROOVEDIAMETERANDDEPTHWASTAKENASAPERCENTAGEOFPUNCHDIAMETERANDSHEETTHICKNESSRESPECTIVELYTHEPUNCHWITHDIAMETEROF46MMAND25DRAFTANGLEWASMADEOFTUNGSTENCARBIDETOWITHSTANDTHEHIGHFORMINGFORCETHEMATERIALOWWASGREATLYAECTEDBYTHEDIAMETERDDESIGNTOOLPARAMETERSPARAMETERSRANGEASPERCENTAGEPARAMETERRANGEINMMAD150OFPUNCHDIAMETERD7MMBD170220OFPUNCHDIAMETERD75105MMT1580OFSHEETTHICKNESST021MMCD170220OFPUNCHDIAMETERD75105MMT1580OFSHEETTHICKNESST021MMRTR021MMOFTHEBLANKHOLDERGROOVEFORMINGFORCESUSEDWEREINTHERANGE3045KN23GEOMETRICALMEASUREMENTSANDMECHANICALCHARACTERIZATIONOFJOINTSTHEGEOMETRYOFTHEJOINTSPRODUCEDHADALARGEINUENCEONTHEJOINTSTRENGTHANDFAILUREMODEASPRESENTEDINTHISSECTIONTHEREFORE,AGEOMETRICALANALYSISWASCARRIEDOUTINORDERTOMAKEACORRELATIONAMONGTHEDIERENTGEOMETRICALPARAMETERSANDSTRENGTHOFTHEJOINTALSO,TOSTUDYTHEMATERIALOWDURINGTHEJOININGPROCESS,VARIOUSPUNCHSTROKESWEREAPPLIEDTOTHETWOSHEETLAYERSTHECLINCHEDTESTSAMPLESWERECUTANDMOUNTEDUSINGCONVENTIONALOPTICALMETALLOGRAPHICMETHODSOFHOTANDCOLDMOUNTINGINAPOLYMERICRESINTHEMOUNTSWERETHENPOLISHEDTOCLEARLYREVEALTHECLINCHEDGEOMETRYUSINGAHIGHMAGNICATIONDIGITALOPTICALMICROSCOPEKEYENCEVHX2000INORDERTOSTUDYTHEMICROSTRUCTUREOFTHECLINCHED,POORLYCLINCHEDORUNCLINCHEDSHEETS,THETESTSAMPLESWERECUTUSINGAPRECISIONSAWTHEYWERETHENMOUNTEDINPOLYMERICRESIN,POLISHEDANDETCHEDACAUSTICETCHANTCONSISTINGOFAMIXTUREOF10GMNAOHAND90MLOFDISTILLEDWATERWASUSEDINAWATERBATHAT60CTHESAMPLESWERETHENDIPPEDIN50NITRICACIDTOCOMPLETETHEETCHINGPROCESSALSO,AFTERETCHING,VICKERSMICROHARDNESSDATAWASOBTAINEDASAMEASUREOFLOCALSTRENGTHENINGOFTHEJOINTFROMINCREASEDPLASTICOW24JOINTTESTINGSINGLESHEARLAPTESTSASWELLASPEELTESTSWERECARRIEDOUTTOASSESSTHEMECHANICALBEHAVIOROFTHEPRODUCEDJOINTFIVESAMPLEWERETESTUNDEREACHCONDITIONTOENSURETESTREPEATABILITYTHESHEETSAMPLESOFSIZE25MMWIDTHAND75MMLENGTHWERECUTFROMAA7075SHEETTHESHEETSWEREDIELESSCLINCHEDWITHANOVERLAPBETWEENTWOSHEETSOF25MMAND50MMFORSINGLESHEARANDPEELTESTSRESPECTIVELY,ASSHOWNINFIG7,WHERETHELOCATIONOFTHEJOINTWASMARKEDBYTWOPERPENDICULARCENTERLINESINTHEGUREAUNIVERSALMTS100KNSERVOHYDRAULICTESTINGSYSTEMWASUTILIZEDFORMECHANICALCHARACTERIZATIONTHETESTSWERECARRIEDOUTATAMBIENTTEMPERATUREWITHACROSSHEADSPEEDOF1MM/MINUNTILTHETWOSHEETSWERECOMPLETELYSEPARATEDTHELOADVERSUSDISPLACEMENTDATAWASCONTINUOUSLYRECORDEDDURINGTHETESTFIG5PHOTOGRAPHSOFDIELESSCLINCHINGTOOLSINTHEPRESENTSTUDYAANDBTOOLINGASSEMBLY,CPUNCH,DPOLYMERICSPRING,ANDEATANVILMKSABRAATIA,MKJAINTHINWALLEDSTRUCTURES1202017421431424FIG7DRAWINGSOFTHESAMPLESUSEDFOR,ASINGLESHEARTESTANDBPEELTESTTHEJOINTLOCATIONCORRESPONDSTOTHEINTERSECTIONOFTHETWOCENTERLINESFIG8ATYPICALFORMINGFORCEVERSUSPUNCHDISPLACEMENTCURVESFORDIELESSCLINCHING3RESULTSANDDISCUSSION31MATERIALOWDURINGJOININGFIG8SHOWSFORMINGCURVEFORMINGFORCEVERSUSPUNCHSTROKEMEASUREDDURINGTHEJOININGPROCESSFORO2TEMPERSHEETGENERALLY,SEVERALSTAGESCANBEDISTINGUISHEDFROMSUCHGRAPHSBASEDONCHANGESINTHECHARACTERISTICSLOPESOFTHECURVESANDCORRESPONDINGGEOMETRYOFTHEJOINTASPRESENTEDINFIG9DURINGSTAGEONEWHICHENDSATPOINTIONTHECURVE,THEBLANKHOLDEREXERTSAPRESSUREIE,ACOMPRESSIVEFORCEINTHECLAMPEDREGIONONTHEPAIROFSHEETMATERIALSSTAGEIIISINITIATEDBYTHEPUNCHCOMINGINCONTACTWITHUPPERSHEETTHEFORMINGFORCEISANINDICATIONOFTHEINITIALINSERTIONOFTHEPUNCHINTOTHEUPPERSHEETSTAGEIIENDSWITHPENETRATIONOFTHEPUNCHINTHEUPPERSHEETONLYTHEUPPERSHEETMATERIALOWSINTHEAXIALDIRECTIONONLY,WHILETHELOWERSHEETOWSINBOTHTHEAXIALANDRADIALDIRECTIONSDURINGTHETHIRDSTAGEBETWEENPOINTSIIANDIIIONTHECURVETHEMATERIALOWINTHERADIALDIRECTIONINCREASESSIGNICANTLYTHEFOURTHSTAGESTARTSWHENTHEUPPERSHEETMATERIALCONTACTSTHETOPOFTHEBLANKHOLDERGROOVEDURINGTHISSTAGETHEOWOFTHEUPPERSHEETINTHERADIALDIRECTIONISINCREASEDSIGNICANTLYANDGEOMETRICALINTERLOCKBEGINSTOFORMINTHEFTH,THEMATERIALOWINTHEAXIALDIRECTIONISLIMITEDBYTHEBLANKHOLDERTHATRESULTSINMUCHINCREASEINGEOMETRICINTERLOCKFINALLY,THEFORCEDROPSDUETOPUNCHRETRACTIONANDTHECHANGEINTHESLOPEISLIKELYANINDICATIONOFTHEENDOFELASTICRECOVERYASTHEPUNCHMOVESUNDERTHEACTIONOFTHEURETHANECOMPRESSIONSPRINGFIG9PRESENTSASCHEMATICOFTHEVESTAGESOFDIELESSCLINCHINGFIG10SHOWSASETOFPHOTOGRAPHSFROMOPTICALLYMOUNTEDCROSSSECTIONSOFTHEDIELESSJOINTSATDIERENTPUNCHSTROKES,FORDIERENTTEMPERSTATESTHEPHOTOGRAPHSHAVEBEENARRANGEDIN4SEPARATECOLUMNS,ONEFOREACHTEMPERSTATEASSHOWNBENEATHEACHOFTHEPHOTOGRAPHS,AHIGHERFORCEWASREQUIREDTOAPPLYTHESAMEPUNCHSTROKEASTHESHEETTEMPERWASCHANGEDTOAHIGHERSTRENGTHTEMPERTHEMOUNTEDSAMPLESALSOHELPEDASSESSTHESPRINGBACKEECTASMEASUREDBYINDENTATIONDEPTHUNDERDIERENTCLINCHINGCONDITIONSFOREXAMPLE,INTHEEARLYSTAGEOFFORMING,AHIGHERSPRINGBACKEECTIE,ASMALLESTPUNCHDEPTHFORTHET6TEMPERANDALOWESTSPRINGBACKORTHELARGESTPUNCHDEPTHFORTHEWTEMPERCOMPARECOLUMNS1AND2OFFIG10WASOBTAINEDTHEHIGHERSPRINGBACKINT6RESULTSFROMAHIGHERYIELDSTRENGTHANDLARGERELASTICSTRAINVALUEFORTHISTEMPERSTATECOMPAREDTOTHEOTHERTEMPERSNOTICEABLY,INTHELASTSTAGE,THEMATERIALOWINTHERADIALDIRECTIONINCREASESSIGNICANTLYFORTHESOFTERTEMPERSTATESLEADINGTOINCREASEDMATERIALOWANDINTURNALARGERAMOUNTOFINTERLOCKFIG11SHOWSNALGEOMETRICALPARAMETERSINTERLOCKDEPTH“U”ANDNECKTHICKNESS“N”ASINFIG3ASAFUNCTIONOFFORMINGFORCEFORPARTIALLYANDFULLYANNEALEDSHEETSSHEETSINT6TEMPERSTATEFAILEDTOPERFORMINTERLOCKINGDUETOLIMITEDOWABILITYINTHEREVERSEAXIALDIRECTION,OPPOSITETOPUNCHMOVEMENTONTHEOTHERHAND,THEOTHERTEMPERSTATESSUCCESSFULLYFORMEDDIELESSJOINTSTHUS,THEOWOFTHEUPPERSHEETMATERIALINTHEDIRECTIONOPPOSITETOPUNCHMOVEMENTFROMTHEEARLIERSTAGESISADECISIVEPARAMETERINTHEFIG9SCHEMATICILLUSTRATIONSOFTHEPROGRESSIONOFDIELESSCLINCHINGFROMLEFTTORIGHTMKSABRAATIA,MKJAINTHINWALLEDSTRUCTURES1202017421431425FIG10OPTICALIMAGESOFTHROUGHTHICKNESSMOUNTEDCROSSSECTIONOFDIELESSJOINTSFORMEDATDIERENTPUNCHSTROKESFORVARIOUSTEMPERSTATESBLANKHOLDERB,D175,ANDT75FIG11GEOMETRICALPARAMETERSUANDNOFCLINCHEDJOINTSASFUNCTIONOFFORMINGFORCEFORPARTIALLYO1ANDFULLYANNEALEDO2SHEETSFORMATIONOFAGOODINTERLOCKINTHEDIELESSCLINCHEDJOINTATAPPROXIMATELY28MMPUNCHSTROKE,INTERLOCKINGSTARTSTOFORMINTHESOFTERTEMPERDUETOINCREASEINTHEMATERIALOWINTHERADIALDIRECTIONADDITIONALLY,BYCOMPARINGTHEOPTICALIMAGESINTHELASTROWINFIG10,ASMALLPROTRUSIONCANBENOTICEDONTHEANVILSIDEDSHEETTHEDEPTHOFTHEPROTRUSIONSHOWSANINCREASEASTHETEMPERCHANGESFROMALOWERSTRENGTHTOAHIGHERSTRENGTHDIELESSCLINCHINGTESTSWEREALSOCONDUCTEDINT6TEMPERTOCOMPAREWITHTHEOTHERFULLYANNEALEDSHEETSAMINIMALINTERLOCKWASACHIEVEDBYPLACINGTHESOFTERFULLYANNEALEDSHEETONTHEPUNCHSIDEANDTHET6SHEETONANVILSIDEFORTHISSHEETCOMBINATION,THEMOSTMATERIALOWINTHEAXIALDIRECTIONOCCURREDINTHESOFTSHEETSLEFTCOLUMNOFPHOTOGRAPHSINFIG12DEMONSTRATESTHEOWOFTHEMATERIALDURINGTHESEEXPERIMENTSHOWEVER,WHENTHESHEETSINT6TEMPERSTATEWASPLACEDONTHEPUNCHSIDE,ASSHOWNINTHERIGHTCOLUMN,NOCLINCHINGCOULDBEACHIEVEDTHISISBECAUSETHEOWOFTHEMATERIALINTHEVICINITYOFTHEPUNCHWASLIMITEDINTHEDIRECTIONOPPOSITETOTHEMOTIONOFTHEPUNCHINFACT,INTHEEARLYSTAGES,THEMATERIALOWOCCURREDINFIG12ASETOFOPTICALIMAGESOFTHECROSSSECTIONSTHROUGHDIELESSCLINCHJOINTSFORMEDINOANDT6TEMPERSTHELEFTANDRIGHTCOLUMNSPRESENTTHECASEOFT6TEMPERSHEETONTHEPUNCHSIDEANDANVILSIDERESPECTIVELYMKSABRAATIA,MKJAINTHINWALLEDSTRUCTURES1202017421431426FIG13OPTICALMICROGRAPHSOFCUTCROSSSECTIONOFDIELESSCLINCHEDJOINTPERFORMEDONPARTIALLYANNEALEDSHEETSTHESAMPLEEXHIBITEDTHEHIGHESTMICROHARDNESSVALUESINTHENECKREGIONASWELLASATTHEBOTTOMCORNERREGIONINBOTHOFTHESHEETS32POSTCLINCHSTRENGTHOFJOINTFIG14ANOPTICALIMAGEOFADIELESSCLINCHJOINTSHOWINGSUPERIMPOSEDVICKERSMICROHARDNESSCONTOURSCLINCHEDJOINTSWEREPRODUCEDUSINGBLANKHOLDERTYPEBWITHGROOVEDEPTHOF25OFSHEETTHICKNESSANDGROOVEDIAMETEROF220OFPUNCHDIAMETERTHESAMEDIRECTIONASTHEPUNCHMOVEMENTTHEREFORE,ITISINFERREDTHATTHEABILITYOFTHEPUNCHSIDEDSHEETMETALTOOWINOPPOSITEOFTHEPUNCHMOVEMENTISCRITICALTOTHEFORMATIONOFTHEINTERLOCKTHISWASNOTTHECASEFORT6TEMPERSHEETFIG13SHOWSTHEOPTICALMICROGRAPHSOFCUTCROSSSECTIONSOFSEVERALDIERENTREGIONSOFDIELESSCLINCHEDJOINTSTHEGRAINSHAPEANDGRAINSIZECHARACTERISTICSFORUNDEFORMEDANDHIGHLYPLASTICALLYDEFORMEDNECKANDBOTTOMREGIONSARECLEARLYREVEALEDTHEAVERAGEGRAINSIZEINTHEUNDEFORMEDSHEETWASABOUT35MTHEGRAINSIZEINTHEHIGHLYDEFORMEDREGIONCOULDNOTBEDETERMINEDRELIABLYFROMOPTICALMICROGRAPHSFIG14SHOWSAMAPOFVICKERSHARDNESSDISTRIBUTIONSTHROUGHCROSSSECTIONOFACLINCHSPECIMENTESTEDATAFORMINGFORCEOF40KNTHEMATERIALBEFOREFORMINGWASPARTIALLYANNEALEDANDHADARELATIVELYLOWMICROHARDNESSOF65VHASEXPECTED,THEMICROHARDNESSINAGIVENREGIONINCREASEDWITHINCREASINGPLASTICDEFORMATIONORPLASTICWORK321SINGLESHEARTESTFIG15A,BSHOWSTHEFORCEDISPLACEMENTTRACESFROMSINGLELAPSHEARTESTSONCLINCHEDJOINTSFORMEDBYUSINGBLANKHOLDERTYPEBWITHGROOVEDIAMETER175OFPUNCHDIAMETERAND40OFSHEETTHICKNESSGROOVEDEPTHTHESAMPLESTESTEDINLAPSHEARWEREOBTAINEDATDIFFERENTFORMINGFORCESUSINGFULLYANNEALEDAA7075SHEETSFORCEDISPLACEMENTTRACESTYPICALLYEXHIBITEDANINITIALLINEARELASTICREGION,FOLLOWEDBYASLOWERRISEOFTHECURVEDUETOADECREASEINTHEJOINTSTINESSFROMGRADUALPULLOUTOFTHEPUNCHSIDEDSHEETTHELOADDROPINTHELASTSTAGECORRESPONDEDTOCRACKINITIATIONFROMTHEINNERSURFAC
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