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)preciselyinspacetransmittherequiredenergytothecuttingzoneformetalremovalObviouslyspindleshaveastronginfluenceonmetalremovalratesandquality

2、ofthemachinedparts.Thispaperreviewsthecurrentstate.andpresentsresearchchallengesofspindletechnology.A.1.1.HistoricalreviewClassically,mainspindlesweredrivenbybeltsorgearsandtherotationalspeedscouldonlybevariedbychangingeitherthetransmissionratioorthenumberofdrivenpolesbyelectricalswitches.

3、Latersimpleelectricalorhydrauliccontrollersweredevelopedandtherotationalspeedofthespindlecouldbechangedbymeansofinfinitelyadjustablerotatingtransformers(WardLeonardsystemofmotorcontrol).Theneedforincreasedproductivityledtohigherspeedmachiningrequirementswhichledtothedevelopmentofnewbearing

4、s,powerelectronicsandinvertersystems.Theprogressinthefieldofthepowerelectronics(staticfrequencyconverter)ledtothedevelopmentofcompactdriveswithlow-costmaintenanceusinghighfrequencythree-phaseasynchronousmotors.Throughtheearly1980’shighspindlespeedswereachievableonlybyusingactivemagneticbea

5、rings.Continuousdevelopmentsinbearings,lubrication,therollingelementmaterialsanddrivesystems(motorsandconverters)haveallowedtheconstructionofdirectdrivemotorspindleswhichcurrentlyfulfillawiderangeofrequirements.A.1.2.PrincipalsetupToday,theoverwhelmingmajorityofmachinetoolsareequippedwithm

6、otorizedspindles.Unlikeexternallydrivenspindles,themotorizedspindlesdonotrequiremechanicaltransmissionelementslikegearsandcouplings.Thespindleshaveatleasttwosetsofmainlyballbearingsystems.Thebearingsystemisthecomponentwiththegreatestinfluenceonthelifetimeofaspindle.Mostcommonlythemotorisar

7、rangedbetweenthetwobearingsystems.Duetohighratioof‘powertovolume’activecoolingisoftenrequired,whichisgenerallyimplementedthroughwaterbasedcooling.Thecoolantflowsthroughacoolingsleevearoundthestatorofthemotorandoftentheouterbearingrings.Sealsatthetoolendofthesp