机械外文翻译中英文VIP免费

第1页共13页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第1页共13页附录附录1英文原文RollingContactBearingsTheconcernofamachinedesignerwithballandrollerbearingsisfivefoldasfollows:(a)lifeinrelationtoload;(b)stiffness,ie.deflectionsunderload;(c)friction;(d)wear;(e)noise.Formoderateloadsandspeedsthecorrectselectionofastandardbearingonthebasisofaloadratingwillbecomeimportantwhereloadsarehigh,althoughthisisusuallyoflessmagnitudethanthatoftheshaftsorothercomponentsassociatedwiththebearing.Wherespeedsarehighspecialcoolingarrangementsbecomenecessarywhichmayincreasefricitionaldrag.Wearisprimarilyassociatedwiththeintroductionofcontaminants,andsealingarrangementsmustbechosenwithregardtothehostilityoftheenvironment.Becausethehighqualityandlowpriceofballandrollerbearingdependsonquantityproduction,thetaskofthemachinedesignerbecomesoneofselectionratherthandesign.Rolling-contactbearingsaregenerallymadewithsteelwhichisthrough-hardenedtoabout900HV,althoughinmanymechanismsspecialracesarenotprovidedandtheinteractingsurfacesarehardenedtoabout600HV.Itisnotsurprisingthat,owingtothehighstressesinvolved,apredominantformoffailureshouldbemetalfatigue,andagooddealofworkisbasedonacceptvaluesoflifeanditisgeneralpracticeinbearingindustrytodefinetheloadcapacityofthebearingasthatvaluebelowwhich90percentofabatchwillexceedlifeofonemillionrevolutions.Notwithstandingthefactthatresponsibilityforbasicdesignofballandrollerbearingsrestswiththebearingmanufacturer,themachinedesignermustformacorrectappreciationofthedutytobeperformedbythebearingandbeconcernednotonlywithbearingselectionbutwiththeconditionsforcorrectinstallation.Thefitofthebearingracesontotheshaftorontothehousingsisofcriticalimportancebecauseoftheircombinedeffectontheinternalclearanceofthebearingaswellaspreservingthedesireddegreeofinterferencefit.Inadequateinterferencecaninduceserioustroublefromfrettingcorrosion.Theinnerraceisfrequentlylocatedaxiallybyagainstashoulder.Aradiusatthispointisessentialfortheavoidanceofstressconcentrationandballracesareprovidedwitharadiusorchamfertofollowspaceforthis.第2页共13页第1页共13页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第2页共13页Wherelifeisnotthedeterminingfactorindesign,itisusualtodeterminemaximumloadingbytheamounttowhichabearingwilldeflectunderload.Thustheconceptof"staticload-carryingcapacity"isunderstoodtomeantheloadthatcanbeappliedtoabearing,whichiseitherstationaryorsubjecttoslightswivelingmotions,withoutimpairingitsrunningqualitiesforsubsequentrotationalmotion.Thishasbeendeterminedbypracticalexperienceastheloadwhichwhenappliedtoabearingresultsinatotaldeformationof0.0025mmforaball25mmindiameter.Thesuccessfulfunctioningofmanybearingsdependsuponprovidingthemwithadequateprotectionagainsttheirenvironment,andinsomecircumstancestheenvironmentmustbeprotectedfromlubricantsorproductsofdeteriorationofthebearingdesign.Moreover,sealswhichareappliedtomovingpartsforanypurposeareofinteresttotribologistsbecausetheyarecomponentsofbearingsystemsandcanonlybedesignedsatisfactorilyonbasisoftheappropriatebearingtheory.Notwithstandingtheirimportance,theamountofresearcheffortthathasbeendevotedtotheunderstandingofthebehaviorofsealshasbeensmallwhencomparedwiththatdevotedtootheraspectsofbearingtechnology.LathesLathesarewidelyusedinindustrytoproduceallkindsofmachinedparts.Somearegeneralpurposemachines...