毕业设计机械类外文文献

IndustrialRobot:AnInternationalJournalbyWilliamT.TownsendVolume27–Number3–2000–pp.181—188President&CEO©MCBUniversityPress–ISSN0143-991X–PDFmadewithMCBpermissionBarrettTechnology,Inc.://://–IndustrialRobotFeatureArticleTheBarrettHandgrasper–programmablyflexibleparthandlingandassemblyAbstractThispaperdetailsthedesignandoperationoftheBarrettHandBH8-250,anintelligent,highlyflexibleeight-axisgripperthatreconfiguresitselfinrealtimetoconformsecurelytoawidevarietyofpartshapeswithouttool-changeinterruptions.Thegrasperbringsenormousvaluetofactoryautomationbecauseit:reducestherequirednumberandsizeofroboticworkcells(whichaverageUS$90,000each–notincludingthehighcostoffootprint)whileboostingfactorythroughput;consolidatesthehodgepodgeproliferationofcustomizedgripper-jawshapesontoacommonprogrammableplatform;andenablesincrementalprocessimprovementandaccommodatesfrequentnew-productintroductions,capabilitiesdeployedinstantlyviasoftwareacrossinternationalnetworksoffactories.IntroductionThispaperintroducesanewapproachtomaterialhandling,partsorting,andcomponentassemblycalled“grasping”,inwhichasinglereconfigurablegrasperwithembeddedintelligencereplacesanentirebankofunique,fixed-shapegrippersandtoolchangers.ToappreciatethemotivationsthatguidedthedesignofBarrett’sgrasper,wemustexplorewhatiswrongwithroboticstoday,theenormouspotentialforroboticsinthefuture,andthedead-endlegacyofgrippersolutions.Forthebenefitsofaroboticsolutiontoberealized,programmableflexibilityisrequiredalongtheentirelengthoftherobot,fromitsbase,allthewaytothetargetworkpiece.ArobotarmenablesprogrammableflexibilityfromthebaseonlyuptotheIndustrialRobot:AnInternationalJournalbyWilliamT.TownsendVolume27–Number3–2000–pp.181—188President&CEO©MCBUniversityPress–ISSN0143-991X–PDFmadewithMCBpermissionBarrettTechnology,Inc.://://:AnInternationalJournalbyWilliamT.TownsendVolume27–Number3–2000–pp.181—188President&CEO©MCBUniversityPress–ISSN0143-991X–PDFmadewithMCBpermissionBarrettTechnology,Inc.://://’spatentedgrasper,illustratedinFigure1,isautomaticallyreconfigurableandhighlyprogrammable,matchingthefunctionalityofvirtuallyanygrippershapeorfixturefunctioninlessthanasecondwithoutpausingtheworkcellthroughputtoexchangegrippers.Fortasksrequiringahighdegreeofflexibilitysuchashandlingvariablyshapedpayloadspresentedinmultipleorientations,agrasperismoresecure,quickertoinstall,andmorecosteffectivethananentirebankofcustom-machinedgripperswithtoolchangersandstorageracks.Foruninterruptedoperation,justoneortwosparegrasperscanserveasemergencybackupsforseveralworkcells,whereasoneortwosparegrippersarerequiredforeachgrippervariation–potentiallydozensperworkcell.And,it’scatastrophicifbothgripperbackupsfailinagrippersystem,sinceitmaybedaysbeforereplacementscanbeidentified,customshapedfromscratch,shipped,andphysicallyreplacedtobringtheaffectedlinebackintooperation.Bycontrast,sincegraspersarephysicallyidentical,theyarealwaysavailableinunlimitedquantity,withallcustomizationprovidedinstantlyinsoftware.GripperlegacyMostoftoday’sroboticparthandlingandassemblingisdonewithgrippers.Ifsurfaceconditionsallow,vacuumsuctionandelectromagnetscanalsobeused,forexampleinhandlingautomobilewindshieldsandbodypanels.Aspartsizesbegintoexceedtheorderof100gms,agripper’sjawsarecustomshapedtoensureasecurehold.Asthedurablemainstayofhandlingandassembly,thesetoolshavechangedlittlesincethebeginningofroboticsthreedecadesago.Grippers,whichactassimplepincers,havetwoorthreeunarticulatedfingers,called“jaws”,whicheitherpivotorremainparallelduringopen/closemotionsasillustratedinFigure2.Wellorganizedcatalogsareavailablefrommanufacturersthatguidetheintegratororcustomerinmatchingvariousgrippercomponents(exceptnaturallyforthecustomjawshape)tothetaskandpartparameters.IndustrialRobot:AnInternationalJournalbyWilliamT.TownsendVolume27–Number3–2000–pp.181—188President&CEO