塑料件振动摩擦焊接的理论与应用手册之二

213.Branson'sapproachtoasuccessfulVibrationTechnologyFig.13Constructionprincipleofalinearvibrationweldingsystem223.1VibrationheadThedriveofBRANSON'spatentedvibra-tionweldingtechniqueisbasedontheelectromagneticprinciple.Asshowninthefigure,thevibrationheadconsistsofthefollowingcomponents:1.Thebridge2.Theelectromagneticcoils3.Thedriverboxincorporatingthelaminatesandthedriverplaten4.Thesprings5.UpperfixtureFig.1423Theelectromagneticdrivemovesthedriverboxagainstthetensileloadofthesprings.ThemassesM1andM2andthespringconstantKformthemechanicalcompo-nentsofthisresonancesystemwherethemassesmoveinlinearvibration.Theamplituderequiredforweldingopera-tionsisdeterminedbymassM1.Therestoringforceofthespringsensuresaccuraterepositioningofthedriverboxtoitscentreposition(tolerance0.01mm)Theamplitudecanbeadaptedtothepar-ticularrequirementsoftheweldingopera-tion.Formachinesoperatingatafre-quencyof100Hz,itrangesfrom1.0to2.0mm.Formachinesoperatingat240Hz,itrangesfrom0.35to0.9mm.Fig.153.2LiftingtableTheliftingtablebringsthepartstobeweldedintocontact.Thetablemaybehydraulically,pneumaticallyorelectricallydriven.Thedesignoftheliftingtableprovidessufficientmassandstabilitytocounterbal-ancethevibrationhead.Thelifttableanddriverplatenincorporaterecessesallowingtheinsertionoflargeparts.BRANSON'spresentlineofVIBequipmentincludestwoweldpressuresystems:243.2.1HydraulicThehydraulicunitswitchesfromtraveltoweldingpressure,optionallybeforeoronreachingtheweldingposition.Simultane-ously,avariabletimedelayisstartedenablingtheadaptiontodifferentapplica-tions.Afterthisdelay,theweldingcyclestarts.Theterminationoftheweldingoperationcanbedepthortimecontrolled.Oncompletionoftheweld,thepresetweldingpressureswitchesovertothepre-setholdpressure.Theweldingpressureaswellastheholdpressuremayamounttoamaximumof3000daN,dependingonthetypeofmachine.Afterthepresetholdtimedelay,theliftingtable,movingtowardsthehomeposition,releasestheweldedparts.3.2.2Electro-mechanical(Option)Theelectricaldrivemovesthelifttabletoafixedpointdependentupontheapplica-tion.Atthisfixedpoint,aseparatepneu-maticsystemisstartedwhichappliestheweldingandholdpressuresafterthetimedelay.Thefollowingsequenceofdelay,weldingandholdtimesisidenticalwiththehydraulicsystem.3.2.3PneumaticOperateslikethehydraulicdrive(point1).Iftheweldingpressureneedstobeappliedinotherplanesthanthevertical,thepneu-maticsystemmaybechosen.3.3ControlThestandardequipmentcomprises,accordingtothetypeofmachine,apro-grammablelogicorarelaycontrol.Thebrandandtypeoftheprogrammablelogiccontroldependsontherequirementsthecontrolhastomeet;consequently,theydifferamongtheindividualtypesofmachines.Theadvantagesofaprogrammablelogiccontrolareobvious,forexample:„Fastmodificationoftheprogramsequence.„Theconnectionofaccessories,suchas-clampingdevicesforthepartstobewelded,-ejectiondrivesfortheweldedparts,-suctionholdingdevices.„Controlsforhandlingdevicesinconnexionwithconveyors,forparttransport,inmanufacturingenviron-mentsrangingfromanassemblylinesystemtoafullyautomaticmanufacturingprocess.Thecontrolsaredesignedinawaythat,additionaltotheautomaticcycle,allsetuppositionscanbeaccessedbymanualcontrol.Weldandholdtimesaredigitallyadjust-ableanddigitallydisplayedduringcycles.Weldandholdpressuresareadjustedbymeansofapotentiometer;thedisplayisanalog.Thepeak-to-peakamplitudeisalsoadjustable;thedisplayisanalog.Partially,dependentonthetypeofequip-ment,thep/pamplitudeisautomaticallyreadjustedtoconformtothepresetvalue(closedloopcircuit).Ofcourse,eachmachinefeaturesautomaticcontrolofthep/pamplitudetoswitchthesystemoffifthepresetvalueisexceeded.253.4Construction(ofthestandardversion)Consistingofaweldconstructionofhollowsteelprofiles,themachinerackrestsself-supportedontheflooroftheassemblyhall,owingtofourverticallyadjustablevibrationdampingfeet.Thevibrationheadismountedinthemachinerackbymeansofavibrationdampingdevice.Thefixtureplatenandtheupperfixturearescrewedtothevibrationhead.Theliftingtablerunsinfourballbearingsontwoguiderodsverticallymountedinthemachinerack.Thehydraulicsystemismountedontopofanaluminumoilcontainerinthemachinerack.Themachinerackisenclosedwithinasoundenclosure.Thesoundenclosureconsistsofabout100mmthickverticalcassetteelements,self-supportedonthefloor,andof80mmthickcassetteelementslaidontopoftheverticalcassetteelements.Asthesoundenclosurestandsdetached,themachineframevibrationsarenottransmittedtotheexterior.Ontheoperatingside,aslidedooropeningverticallyallowstheinsertionofthepartstobewelded.Itisequippedwithsafetydevices.Theinteriorcanbeaccessedforserviceandmaintenancethroughdoorsonthetopandontherear.Thecontrolcabinetislocatedatthesideofthesoundenclosure.Allnecessarycontrolsandindicatorsareonthefrontpanelofthecontrolcabinet.Thecontrolcabinethousesthepowersupplyandthecontrols.ABRANSONvibrationweldercomprisesthefollowingcomponents:263.5SpecialdesignconceptsLargeandcomplextechnicalmouldingsaredifficultorimpossibletoweldonstand-ardisedtypesofequipment.Yet,machinesdesignedtoparticularspec-ificationsrendertheefficientmanufactur-ingofsuchpartsfeasible.