外文翻译---机床主轴单元.docx

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1、附录A英文原文MachinetoolspindleunitsA.1IntroductionMachinetoolspindlesbasicallyfulfilltwotasks:rotatethetools(drilling,millingandgrinding)orworkpiece(turning)preciselyinspacetransmittherequiredenergytothecuttingzoneformetalremovalObviouslyspindleshaveastronginfluence

2、onmetalremovalratesandqualityofthemachinedparts.Thispaperreviewsthecurrentstate.andpresentsresearchchallengesofspindletechnology.A.1.1.HistoricalreviewClassically,mainspindlesweredrivenbybeltsorgearsandtherotationalspeedscouldonlybevariedbychangingeitherthetran

3、smissionratioorthenumberofdrivenpolesbyelectricalswitches.Latersimpleelectricalorhydrauliccontrollersweredevelopedandtherotationalspeedofthespindlecouldbechangedbymeansofinfinitelyadjustablerotatingtransformers(WardLeonardsystemofmotorcontrol).Theneedforincreas

4、edproductivityledtohigherspeedmachiningrequirementswhichledtothedevelopmentofnewbearings,powerelectronicsandinvertersystems.Theprogressinthefieldofthepowerelectronics(staticfrequencyconverter)ledtothedevelopmentofcompactdriveswithlow-costmaintenanceusinghighfre

5、quencythree-phaseasynchronousmotors.Throughtheearly1980’shighspindlespeedswereachievableonlybyusingactivemagneticbearings.Continuousdevelopmentsinbearings,lubrication,therollingelementmaterialsanddrivesystems(motorsandconverters)haveallowedtheconstructionofdire

6、ctdrivemotorspindleswhichcurrentlyfulfillawiderangeofrequirements.A.1.2.PrincipalsetupToday,theoverwhelmingmajorityofmachinetoolsareequippedwithmotorizedspindles.Unlikeexternallydrivenspindles,themotorizedspindlesdonotrequiremechanicaltransmissionelementslikege

7、arsandcouplings.Thespindleshaveatleasttwosetsofmainlyballbearingsystems.Thebearingsystemisthecomponentwiththegreatestinfluenceonthelifetimeofaspindle.Mostcommonlythemotorisarrangedbetweenthetwobearingsystems.Duetohighratioof‘powertovolume’activecoolingisoftenre

8、quired,whichisgenerallyimplementedthroughwaterbasedcooling.Thecoolantflowsthroughacoolingsleevearoundthestatorofthemotorandoftentheouterbearingrings.Sealsatthetoolendofthesp