外文翻译---机床主轴单元

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

2、metalremovalratesandqualityofthemachinedparts.Thispaperreviewsthecurrentstate.andpresentsresearchchallengesofspindletechnology.A.1.1.HistoricalreviewClassically,mainspindlesweredrivenbybeltsorgearsandtherotationalspeedscouldonlybevariedbychangingeitherthetransmis

3、sionratioorthenumberofdrivenpolesbyelectricalswitches.Latersimpleelectricalorhydrauliccontrollersweredevelopedandtherotationalspeedofthespindlecouldbechangedbymeansofinfinitelyadjustablerotatingtransformers(WardLeonardsystemofmotorcontrol).Theneedforincreasedprod

4、uctivityledtohigherspeedmachiningrequirementswhichledtothedevelopmentofnewbearings,powerelectronicsandinvertersystems.Theprogressinthefieldofthepowerelectronics(staticfrequencyconverter)ledtothedevelopmentofcompactdriveswithlow-costmaintenanceusinghighfrequencyth

5、ree-phaseasynchronousmotors.Throughtheearly1980’shighspindlespeedswereachievableonlybyusingactivemagneticbearings.Continuousdevelopmentsinbearings,lubrication,therollingelementmaterialsanddrivesystems(motorsandconverters)haveallowedtheconstructionofdirectdrivemot

6、orspindleswhichcurrentlyfulfillawiderangeofrequirements.A.1.2.PrincipalsetupToday,theoverwhelmingmajorityofmachinetoolsareequippedwithmotorizedspindles.Unlikeexternallydrivenspindles,themotorizedspindlesdonotrequiremechanicaltransmissionelementslikegearsandcoupli

7、ngs.Thespindleshaveatleasttwosetsofmainlyballbearingsystems.Thebearingsystemisthecomponentwiththegreatestinfluenceonthelifetimeofaspindle.Mostcommonlythemotorisarrangedbetweenthetwobearingsystems.Duetohighratioof‘powertovolume’activecoolingisoftenrequired,whichis

8、generallyimplementedthroughwaterbasedcooling.Thecoolantflowsthroughacoolingsleevearoundthestatorofthemotorandoftentheouterbearingrings.Sealsatthetoolendofthesp