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1、本科生毕业论文（设计）英文翻译学院机电工程学院专业班级 机制07级2班撰写日期：2010年5月12日17EXTENDINGBEARINGLIFEAbstract：Natureworkshardtodestroybearings,buttheirchancesofsurvivalcanbeimprovedbyfollowingafewsimpleguidelines.Extremeneglectinabearingleadstooverheatingandpossiblyseizureor,atworst,anexp
2、losion.Butevenafailedbearingleavescluesastowhatwentwrong.Afteralittledetectivework,actioncanbetakentoavoidarepeatperformance.Keywords:bearingsfailureslifeBearingsfailforanumberofreasons，butthemostcommonaremisapplication，contamination，improperlubricant，shipping
3、orhandlingdamage，andmisalignment.Theproblemisoftennotdifficulttodiagnosebecauseafailedbearingusuallyleavestelltalesignsaboutwhatwentwrong．However，whileapostmortemyieldsgoodinformation，itisbettertoavoidtheprocessaltogetherbyspecifyingthebearingcorrectlyinThefir
4、stplace．Todothis，itisusefultoreviewthemanufacturerssizingguidelinesandoperatingcharacteristicsfortheselectedbearing.Equallycriticalisastudyofrequirementsfornoise,torque,andrunout,aswellaspossibleexposuretocontaminants,hostileliquids,andtemperatureextremes.This
5、canprovidefurthercluesastowhetherabearingisrightforajob.1WhybearingsfailAbout40%ofballbearingfailuresarecausedbycontaminationfromdust,dirt,shavings,andcorrosion.Contaminationalsocausestorqueandnoiseproblems,andisoftentheresultofimproperhandlingortheapplication
6、environment．Fortunately,abearingfailurecausedbyenvironmentorhandlingcontaminationispreventable，andasimplevisualexaminationcaneasilyidentifythecause．Conductingapostmortemil1ustrateswhattolookforonafailedorfailingbearing．Then，understandingthemechanismbehindthefa
7、ilure,suchasbrinellingorfatigue,helpseliminatethesourceoftheproblem.Brinellingisonetypeofbearingfailureeasilyavoidedbyproperhandingandassembly.Itischaracterizedbyindentationsinthebearingracewaycausedbyshockloading－suchaswhenabearingisdropped-orincorrectassembl
8、y.Brinellingusuallyoccurswhenloadsexceedthematerialyieldpoint(350,000psiinSAE52100chromesteel)．Itmayalsobecausedbyimproperassembly,Whichplacesaloadacrossthe17races．Racewaydentsalso
