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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,anexplosio
2、n.Butevenafailedbearingleavescluesastowhatwentwrong.Afteralittledetectivework,actioncanbetakentoavoidarepeatperformance.Keywords:bearingsfailureslifeBearingsfailforanumberofreasons，butthemostcommonaremisapplication，contamination，improperlubricant，shippingorhandling
3、damage，andmisalignment.Theproblemisoftennotdifficulttodiagnosebecauseafailedbearingusuallyleavestelltalesignsaboutwhatwentwrong．However，whileapostmortemyieldsgoodinformation，itisbettertoavoidtheprocessaltogetherbyspecifyingthebearingcorrectlyinThefirstplace．Todothi
4、s，itisusefultoreviewthemanufacturerssizingguidelinesandoperatingcharacteristicsfortheselectedbearing.Equallycriticalisastudyofrequirementsfornoise,torque,andrunout,aswellaspossibleexposuretocontaminants,hostileliquids,andtemperatureextremes.Thiscanprovidefurtherclu
5、esastowhetherabearingisrightforajob.1WhybearingsfailAbout40%ofballbearingfailuresarecausedbycontaminationfromdust,dirt,shavings,andcorrosion.Contaminationalsocausestorqueandnoiseproblems,andisoftentheresultofimproperhandlingortheapplicationenvironment．Fortunately,a
6、bearingfailurecausedbyenvironmentorhandlingcontaminationispreventable，andasimplevisualexaminationcaneasilyidentifythecause．Conductingapostmortemil1ustrateswhattolookforonafailedorfailingbearing．Then，understandingthemechanismbehindthefailure,suchasbrinellingorfatigu
7、e,helpseliminatethesourceoftheproblem.Brinellingisonetypeofbearingfailureeasilyavoidedbyproperhandingandassembly.Itischaracterizedbyindentationsinthebearingracewaycausedbyshockloading－suchaswhenabearingisdropped-orincorrectassembly.Brinellingusuallyoccurswhenloadse
8、xceedthematerialyieldpoint(350,000psiinSAE52100chromesteel)．Itmayalsobecausedbyimproperassembly,Whichplacesaloadacrossthe17races．Racewaydentsalso
