machine tool spindle unit(综述)

MachinetoolspindleunitsE.Abele(2)a,*,Y.Altintas(1)b,C.Brecher(2)caInstituteofProductionManagement,TechnologyandMachineTools(PTW),TechnischeUniversita¨tDarmstadt,GermanybManufacturingAutomationLaboratory,UniversityofBritishColumbia,Vancouver,CanadacLaboratoryforMachineToolsandProductionEngineering(WZL),RWTHAachen,Germany1.IntroductionMachinetoolspindlesbasicallyfulfilltwotasks:rotatethetools(drilling,millingandgrinding)orworkpiece(turning)preciselyinspacetransmittherequiredenergytothecuttingzoneformetalremovalObviouslyspindleshaveastronginfluenceonmetalremovalratesandqualityofthemachinedparts.Thispaperreviewsthecurrentstateandpresentsresearchchallengesofspindletechnology.1.1.HistoricalreviewClassically,mainspindlesweredrivenbybeltsorgearsandtherotationalspeedscouldonlybevariedbychangingeitherthetransmissionratioorthenumberofdrivenpolesbyelectricalswitches.Latersimpleelectricalorhydrauliccontrollersweredevelopedandtherotationalspeedofthespindlecouldbechangedbymeansofinfinitelyadjustablerotatingtransformers(WardLeonardsystemofmotorcontrol).Theneedforincreasedproductivityledtohigherspeedmachiningrequirementswhichledtothedevelopmentofnewbearings,powerelectronicsandinvertersystems.Theprogressinthefieldofthepowerelectronics(staticfrequencyconverter)ledtothedevelopmentofcompactdriveswithlow-costmaintenanceusinghighfrequencythree-phaseasynchronousmotors.Throughtheearly1980’shighspindlespeedswereachievableonlybyusingactivemagneticbearings.Continuousdevelopmentsinbearings,lubrication,therollingelementmaterialsanddrivesystems(motorsandconverters)haveallowedtheconstructionofdirectdrivemotorspindleswhichcurrentlyfulfillawiderangeofrequirements.AhistoricalreviewofspindletechnologyisgiveninFig.1.1.2.PrincipalsetupToday,theoverwhelmingmajorityofmachinetoolsareequippedwithmotorizedspindles.Unlikeexternallydrivenspindles,themotorizedspindlesdonotrequiremechanicaltransmissionelementslikegearsandcouplings.AmotorspindlemainlyconsistsoftheelementsshowninFig.2.Thespindleshaveatleasttwosetsofmainlyballbearingsystems.Thebearingsystemisthecomponentwiththegreatestinfluenceonthelifetimeofaspindle.Mostcommonlythemotorisarrangedbetweenthetwobearingsystems.Duetohighratioof‘powertovolume’activecoolingisoftenrequired,whichisgenerallyimplementedthroughwaterbasedcooling.Thecoolantflowsthroughacoolingsleevearoundthestatorofthemotorandoftentheouterbearingrings.Sealsatthetoolendofthespindlepreventtheintrusionofchipsandcuttingfluid.Oftenthisisdonewithpurgeairandalabyrinthseal.AstandardizedtoolinterfacesuchasHSKandSKisplacedatthespindlesfrontend.Aclampingsystemisusedforfastautomatictoolchanges.Ideally,anunclampingunit(drawbar)whichcanalsomonitortheclampingforceisneededforreliablemachining.Ifcuttingfluidhastobetransmittedthroughthetooltothecutter,adequatechannelsandarotaryunionbecomerequiredfeaturesoftheclampingsystem.Today,nearlyeveryspindleisequippedwithsensorsformonitoringthemotortemperature(thermistorsorthermo-couples)andthepositionoftheclampingsystem.Additionalsensorsformonitoringthebearings,thedriveandtheprocessstabilitycanbeattached,butarenotcommoninmanyindustrialapplications.CIRPAnnals-ManufacturingTechnology59(2010)781–802ARTICLEINFOKeywords:SpindleMechatronicMachinetoolsABSTRACTThispaperpresentsthestate-of-the-artinmachinetoolmainspindleunitswithfocusonmotorizedspindleunitsforhighspeedandhighperformancecutting.Detailedinformationisgivenaboutthemaincomponentsofspindleunitsregardinghistoricaldevelopment,recentchallengesandfuturetrends.Anoverviewofrecentresearchprojectsinspindledevelopmentisgiven.Advancedmethodsofmodelingthethermalanddynamicalbehaviorofspindleunitsareshowninoverviewwithspecificresults.Furthermoreconceptsforsensorandactuatorintegrationarepresentedwhichallfocusonincreasingproductivityandreliability.2010CIRP.*Correspondingauthor.ContentslistsavailableatScienceDirectCIRPAnnals-ManufacturingTechnologyjournalhomepage:–seefrontmatter2010CIRP.doi:10.1016/j.cirp.2010.05.002Thefocusofthispaperisthespindletechnology.ToclearlylimitthetopicsofthispaperthechosensystemboundariesareillustratedinFig.3.1.3.StateoftheartCurrentspindlemanufacturersofferwidevarietyofspindlesolutionsfortheapplicationareasshowninFig.4.Spindleswithhighpowerandhighspeedsaremainlydevelopedforthemachiningoflargealuminumframesintheaerospaceindustry.Spindleswithextremelyhighspeedsandlowpowerareusedinelectronicsindustryfordrillingprintedcircuitboards(PCB).1.4.ActualdevelopmentareasinindustryCurrentdevelopmentsinmotorspindleindustrialapplicationfocusonmotortechnology,improvingtotalcostofownership(TCO)andconditionmonitoringforpredictivemaintenance(seeFig.5).Anothercentralissueisthedevelopmentofdrivesystemswhichneutralizetheexistingconstraintsofpowerandoutputfrequencywhilereducingtheheatingofthespindleshaft.Particularattentionwaspaidtotheincreaseofthereliablereachablerotationalspeedsinthepast.However,thefocushaschangedtowardshighertorqueatspeedsupto15,000rpm.BecauseofIncreasedrequirementsinreliability,life-cycleandpredictablemain