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ID:39390062
大小:59.50 KB
页数:13页
时间:2019-07-02
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1、附录附录1英文原文RollingContactBearingsTheconcernofamachinedesignerwithballandrollerbearingsisfivefoldasfollows:(a)lifeinrelationtoload;(b)stiffness,ie.deflectionsunderload;(c)friction;(d)wear;(e)noise.Formoderateloadsandspeedsthecorrectselectionofastandardbearingonthebasisofaloadratingwillbecomeimporta
2、ntwhereloadsarehigh,althoughthisisusuallyoflessmagnitudethanthatoftheshaftsorothercomponentsassociatedwiththebearing.Wherespeedsarehighspecialcoolingarrangementsbecomenecessarywhichmayincreasefricitionaldrag.Wearisprimarilyassociatedwiththeintroductionofcontaminants,andsealingarrangementsmustbec
3、hosenwithregardtothehostilityoftheenvironment.Becausethehighqualityandlowpriceofballandrollerbearingdependsonquantityproduction,thetaskofthemachinedesignerbecomesoneofselectionratherthandesign.Rolling-contactbearingsaregenerallymadewithsteelwhichisthrough-hardenedtoabout900HV,althoughinmanymecha
4、nismsspecialracesarenotprovidedandtheinteractingsurfacesarehardenedtoabout600HV.Itisnotsurprisingthat,owingtothehighstressesinvolved,apredominantformoffailureshouldbemetalfatigue,andagooddealofworkisbasedonacceptvaluesoflifeanditisgeneralpracticeinbearingindustrytodefinetheloadcapacityofthebeari
5、ngasthatvaluebelowwhich90percentofabatchwillexceedlifeofonemillionrevolutions.Notwithstandingthefactthatresponsibilityforbasicdesignofballandrollerbearingsrestswiththebearingmanufacturer,themachinedesignermustformacorrectappreciationofthedutytobeperformedbythebearingandbeconcernednotonlywithbear
6、ingselectionbutwiththeconditionsforcorrectinstallation.Thefitofthebearingracesontotheshaftorontothehousingsisofcriticalimportancebecauseoftheircombinedeffectontheinternalclearanceofthebearingaswellaspreservingthedesireddegreeofinterferencefit.Inadequateinterferencecaninduceserioustroublefromfret
7、tingcorrosion.Theinnerraceisfrequentlylocatedaxiallybyagainstashoulder.Aradiusatthispointisessentialfortheavoidanceofstressconcentrationandballracesareprovidedwitharadiusorchamfertofollowspaceforthis.Wherelifeisnotthedetermi
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