外文原文.pdf

EXPERIMENTALINVESTIGATIONOFLASERSURFACETEXTUREDPARALLELTHRUSTBEARINGSIETSION,GHALPERIN,VBRIZMERANDYKLIGERMANDEPTOFMECHANICALENGINEERINGTECHNION,HAIFA32000,ISRAELRECEIVED14SEPTEMBER2003ACCEPTED29DECEMBER2003PERFORMANCEENHANCEMENTSBYLASERSURFACETEXTURINGLSTOFPARALLELTHRUSTBEARINGSISEXPERIMENTALLYINVESTIGATEDTESTRESULTSARECOMPAREDWITHATHEORETICALMODELANDGOODCORRELATIONISFOUNDOVERTHERELEVANTOPERATINGCONDITIONSACOMPARISONOFTHEPERFORMANCEOFUNIDIRECTIONALANDBIDIRECTIONALPARTIALLSTBEARINGSWITHTHATOFABASELINE,UNTEXTUREDBEARINGISPRESENTEDSHOWINGTHEBENEFITSOFLSTINTERMSOFINCREASEDCLEARANCEANDREDUCEDFRICTIONKEYWORDSFLUIDFILMBEARINGS,SLIDERBEARINGS,SURFACETEXTURING1INTRODUCTIONTHECLASSICALTHEORYOFHYDRODYNAMICLUBRICATIONYIELDSLINEARCOUETTEVELOCITYDISTRIBUTIONWITHZEROPRESSUREGRADIENTSBETWEENSMOOTHPARALLELSURFACESUNDERSTEADYSTATESLIDINGTHISRESULTSINANUNSTABLEHYDRODYNAMICFILMTHATWOULDCOLLAPSEUNDERANYEXTERNALFORCEACTINGNORMALTOTHESURFACESHOWEVER,EXPERIENCESHOWSTHATSTABLELUBRICATINGFILMSCANDEVELOPBETWEENPARALLELSLIDINGSURFACES,GENERALLYBECAUSEOFSOMEMECHANISMTHATRELAXESONEORMOREOFTHEASSUMPTIONSOFTHECLASSICALTHEORYASTABLEFLUIDFILMWITHSUCIENTLOADCARRYINGCAPACITYINPARALLELSLIDINGSURFACESCANBEOBTAINED,FOREXAMPLE,WITHMACROORMICROSURFACESTRUCTUREOFDIERENTTYPESTHESEINCLUDEWAVINESS1ANDPROTRUDINGMICROASPERITIES24AGOODLITERATUREREVIEWONTHESUBJECTCANBEFOUNDINREF5MORERECENTLY,LASERSURFACETEXTURINGLST68,ASWELLASINLETROUGHENINGBYLONGITUDINALORTRANSVERSEGROOVES9WERESUGGESTEDTOPROVIDELOADCAPACITYINPARALLELSLIDINGTHEINLETROUGHNESSCONCEPTOFTONDER9ISBASEDONEECTIVECLEARANCEREDUCTIONINTHESLIDINGDIRECTIONANDINTHISRESPECTITISIDENTICALTOTHEPARTIALLSTCONCEPTDESCRIBEDINREF10FORGENERATINGHYDROSTATICEECTINHIGHPRESSUREMECHANICALSEALSVERYRECENTLYWANGETAL11DEMONSTRATEDEXPERIMENTALLYADOUBLINGOFTHELOADCARRYINGCAPACITYFORTHESURFACETEXTUREDESIGNBYREACTIVEIONETCHINGOFSICPARALLELTHRUSTBEARINGSSLIDINGINWATERTHESESIMPLEPARALLELTHRUSTBEARINGSAREUSUALLYFOUNDINSEALLESSPUMPSWHERETHEPUMPEDFLUIDISUSEDASTHELUBRICANTFORTHEBEARINGSDUETOTHEPARALLELSLIDINGTHEIRPERFORMANCEISPOORERTHANMORESOPHISTICATEDTAPEREDORSTEPPEDBEARINGSBRIZMERETAL12DEMONSTRATEDTHEPOTENTIALOFLASERSURFACETEXTURINGINTHEFORMOFREGULARMICRODIMPLESFORPROVIDINGLOADCARRYINGCAPACITYWITHPARALLELTHRUSTBEARINGSAMODELOFATEXTUREDPARALLELSLIDERWASDEVELOPEDANDTHEEECTOFSURFACETEXTURINGONLOADCARRYINGCAPACITYWASANALYZEDTHEOPTIMUMPARAMETERSOFTHEDIMPLESWEREFOUNDINORDERTOOBTAINMAXIMUMLOADCARRYINGCAPACITYAMICRODIMPLECOLLECTIVEEECTWASIDENTIFIEDTHATISCAPABLEOFGENERATINGSUBSTANTIALLOADCARRYINGCAPACITY,APPROACHINGTHATOFOPTIMUMCONVENTIONALTHRUSTBEARINGSTHEPURPOSEOFTHEPRESENTPAPERISTOINVESTIGATEEXPERIMENTALLYTHEVALIDITYOFTHEMODELDESCRIBEDINREF12BYTESTINGPRACTICALTHRUSTBEARINGSANDCOMPARINGTHEPERFORMANCEOFLSTBEARINGSWITHTHATOFTHETHEORETICALPREDICTIONSANDWITHTHEPERFORMANCEOFSTANDARDNONTEXTUREDBEARINGS2BACKGROUNDACROSSSECTIONOFTHEBASICMODELTHATWASANALYZEDINREF12ISSHOWNINFIGURE1ASLIDERHAVINGAWIDTHBISPARTIALLYTEXTUREDOVERAPORTIONBPABOFITSWIDTHTHETEXTUREDSURFACECONSISTSOFMULTIPLEDIMPLESWITHADIAMETER2RC3P,DEPTHHC3PANDAREADENSITYSPASARESULTOFTHEHYDRODYNAMICPRESSUREGENERATEDBYTHEDIMPLESTHESLIDINGSURFACESWILLBESEPARATEDBYACLEARANCEHC30DEPENDINGONTHESLIDINGVELOCITYU,THEFLUIDVISCOSITYLANDTHEEXTERNALLOADWC3ITWASFOUNDINREF12THATANOPTIMUMRATIOEXISTSFORTHEPARAMETERHPHC3PHC30THATPROVIDESMAXIMUMDIMENSIONLESSLOADCARRYINGCAPACITYWWC3HC302LULB2WHERELISTOWHOMCORRESPONDENCESHOULDBEADDRESSEDEMAILETSIONTXTECHNIONACIL10238883/04/08000295/0C2112004PLENUMPUBLISHINGCORPORATIONTRIBOLOGYLETTERS,VOL17,NO2,AUGUST2004C2112004295THEBEARINGLENGTH,ANDTHISOPTIMUMVALUEISHP125ITWASFURTHERFOUNDINREF12THATANOPTIMUMVALUEEXISTSFORTHETEXTUREDPORTIONADEPENDINGONTHEBEARINGASPECTRATIOL/BTHISBEHAVIORISSHOWNINFIGURE2FORABEARINGWITHL/B075ATVARIOUSVALUESOFTHEAREADENSITYSPASCANBESEENINTHERANGEOFSPVALUESFROM018TO072THEOPTIMUMAVALUEVARIESFROM07TO055,RESPECTIVELYITCANALSOBESEENFROMFIGURE2THATFORA085NOOPTIMUMVALUEEXISTSFORSPANDTHEMAXIMUMLOADWINCREASESWITHINCREASINGSPHENCE,THELARGESTAREADENSITYTHATCANBEPRACTICALLYOBTAINEDWITHTHELASERTEXTURINGISDESIREDITISALSOINTERESTINGTONOTEFROMFIGURE2THEADVANTAGEOFPARTIALLSTA1OVERTHEFULLLSTA1FORBEARINGAPPLICATIONSATSP05,FOREXAMPLE,THELOADWATA06ISABOUTTHREETIMESHIGHERTHANITSVALUEATA1AFULLACCOUNTOFTHISBEHAVIORISGIVENINREF123EXPERIMENTALTHETESTEDBEARINGSCONSISTOFSINTEREDSICDISKS10MMTHICK,HAVING85MMOUTERDIAMETERAND40MMINNERDIAMETEREACHBEARINGSEEFIGURE3COMPRISESAFLATROTORAANDASIXPADSTATORBTHEBEARINGSWEREPROVIDEDWITHANORIGINALSURFACEFINISHBYLAPPINGTOAROUGHNESSAVERAGERA003LMEACHPADHASANASPECTRATIOOF075WHENITSWIDTHISMEASUREDALONGTHEMEANDIAMETEROFTHESTATORTHEPHOTOGRAPHSOFTWOPARTIALLSTSTATORSARESHOWNINFIGURE4WHERETHETEXTUREDAREASAPPEARASBRIGHTERMATTSURFACESTHEFIRSTSTATORINDICATEDAISAUNIDIRECTIONALBEARINGWITHTHEPARTIALLSTADJACENTTOTHELEADINGEDGEOFEACHPAD,SIMILARTOTHEMODELSHOWNINFIGURE1THESECONDSTATORBISABIDIRECTIONALVERSIONOFAPARTIALLSTBEARINGHAVINGTWOEQUALTEXTUREDPORTIONS,A/2,ONEACHOFTHEPADENDSTHELASERTEXTURINGPARAMETERSWERETHEFOLLOWINGDIMPLEDEPTHHC3P65C605LM,DIMPLEDIAMETER2RC3P60C65LMANDDIMPLEAREADENSITYSP06C6003THESEDIMPLEDIMENSIONSWEREOBTAINEDWITH4PULSESOF30NSDURATIONAND4MJEACHUSINGA5KHZPULSATINGNDYAGLASERTHETEXTUREDPORTIONOFTHEUNIDIRECTIONALBEARINGWASA073ANDTHATOFTHEBIDIRECTIONALBEARINGWASA063ASCANBESEENFROMFIGURE2BOTHTHESEAVALUESSHOULDPRODUCELOADCARRYINGCAPACITYVARYCLOSETOTHEMAXIMUMTHEORETICALVALUETHETESTRIGISSHOWNSCHEMATICALLYINFIGURE5ANELECTRICALMOTORTURNSASPINDLETOWHICHANUPPERHOLDEROFTHEROTORISATTACHEDASECONDLOWERHOLDERFIGURE1ACROSSSECTIONOFAPARTIALLYLASERSURFACETEXTUREDPARALLELSLIDER0000500100150020025003003500102030405060708091TEXTUREDPORTION,ALOADCAPACITY,WSP018SP032SP05SP072L/B075HP125FIGURE2DIMENSIONLESSLOADCARRYINGCAPACITY,W,VSTEXTUREDPORTION,A,FORVARIOUSDENSITIES,SP296IETSIONETAL/INVESTIGATIONOFLSTPARALLELTHRUSTBEARINGSOFTHESTATORISFIXEDTOAHOUSING,WHICHRESTSONAJOURNALBEARINGANDANAXIALLOADINGMECHANISMTHATCANFREELYMOVEINTHEAXIALDIRECTIONANARMTHATPRESSESAGAINSTALOADCELLANDTHEREBYPERMITSFRICTIONTORQUEMEASUREMENTSPREVENTSTHEFREEROTATIONOFTHISHOUSINGAXIALLOADINGISPROVIDEDBYMEANSOFDEADWEIGHTSONALEVERANDISMEASUREDWITHASECONDLOADCELLAPROXIMITYPROBETHATISATTACHEDTOTHELOWERHOLDEROFTHESTATORALLOWSONLINEMEASUREMENTSOFTHECLEARANCECHANGEBETWEENROTORANDSTATORASTHEHYDRODYNAMICEECTSCAUSEAXIALMOVEMENTOFTHEHOUSINGTOWHICHTHESTATORHOLDERISFIXEDTAPWATERISSUPPLIEDBYGRAVITYFROMALARGETANKTOTHECENTEROFTHEBEARINGANDTHELEAKAGEFROMTHEBEARINGISCOLLECTEDANDRECIRCULATEDATHERMOCOUPLEADJACENTTOTHEOUTERDIAMETEROFTHEBEARINGALLOWSMONITORINGOFTHEWATERTEMPERATUREASTHEWATEREXITTHEBEARINGAPCISUSEDTOCOLLECTANDPROCESSDATAONLINEHENCE,THEINSTANTANEOUSCLEARANCE,FRICTIONCOECIENT,BEARINGSPEEDANDEXITWATERTEMPERATURECANBEMONITOREDCONSTANTLYTHETESTPROTOCOLINCLUDESIDENTIFYINGAREFERENCEZEROPOINTFORTHECLEARANCEMEASUREMENTSBYFIRSTLOADINGANDTHENUNLOADINGASTATIONARYBEARINGOVERTHEFULLLOADRANGETHENTHELOWESTAXIALLOADISAPPLIED,THEWATERSUPPLYVALVEISOPENEDANDTHEMOTORTURNEDONAXIALLOADINGISINCREASEDBYSTEPSOF40NANDEACHLOADSTEPISMAINTAINEDFOR5MINFOLLOWINGTHESTABILIZATIONOFTHEFRICTIONCOECIENTATASTEADYSTATEVALUETHEBEARINGSPEEDANDWATERTEMPERATUREAREMONITOREDTHROUGHOUTTHETESTFORANYIRREGULARITIESTHETESTENDSWHENAMAXIMUMAXIALLOADOF460NISREACHEDORIFTHEFRICTIONCOECIENTEXCEEDSAVALUEOF035ATTHEENDOFTHELASTLOADSTEPTHEMOTORANDWATERSUPPLYARETURNEDOANDTHEREFERENCEFORTHECLEARANCEMEASUREMENTSISRECHECKEDTESTSAREPERFORMEDATTWOSPEEDSOF1500AND3000RPMCORRESPONDINGTOAVERAGESLIDINGVELOCITIESOF49AND98M/S,RESPECTIVELYANDEACHTESTISREPEATEDATLEASTTHREETIMES4RESULTSANDDISCUSSIONASAFIRSTSTEPTHEVALIDITYOFTHETHEORETICALMODELINREF12WASEXAMINEDBYCOMPARINGTHETHEORETICALANDEXPERIMENTALRESULTSOFBEARINGCLEARANCEVERSUSBEARINGLOADFORAUNIDIRECTIONALPARTIALLSTBEARINGTHERESULTSARESHOWNINFIGURE6FORTHETWOSPEEDSOF1500AND3000RPMWHERETHESOLIDANDDASHEDLINESCORRESPONDTOTHEMODELANDEXPERIMENT,RESPECTIVELYASCANBESEEN,THEAGREEMENTBETWEENTHEMODELANDTHEEXPERIMENTISGOOD,WITHDIERENCESOFLESSTHAN10,ASLONGASTHELOADISABOVE150NATLOWERLOADSTHEMEASUREDEXPERIMENTALCLEARANCESAREMUCHLARGERTHANTHEMODELPREDICTIONS,PARTICULARLYATTHEHIGHERSPEEDOF3000RPMWHEREAT120NTHEMEASUREDCLEARANCEIS20LM,WHICHISABOUT60HIGHERTHANTHEPREDICTEDVALUEITTURNSOUTTHATTHECOMBINATIONOFSUCHLARGECLEARANCESANDRELATIVELYLOWVISCOSITYOFTHEWATERMAYRESULTINTURBULENTFLUIDFILMHENCE,THEASSUMPTIONOFLAMINARFLOWONWHICHTHESOLUTIONOFTHEREYNOLDSEQUATIONINREF12ISBASEDMAYBEVIOLATEDFIGURE3APHOTOGRAPHOFTHEPARALLELTHRUSTBEARINGSHOWINGTHEFLATROTORAANDTHESIXPADSSTATORBFIGURE4APHOTOGRAPHOFTWOTEXTUREDSTATORSSHOWINGAUNIDIRECTIONALAANDABIDIRECTIONALBVERSIONSOFTHEPARTIALLSTTHRUSTBEARINGMOTORSPINDLEWATERSUPPLYVELOCITYGAUGEPROXIMITYPROBEBEARINGROTORCLEARANCETHERMOCOUPLELOADCELLSLOADBEARINGSTATORFIGURE5ASCHEMATICDESCRIPTIONOFTHETESTRIGETSIONETAL/EXPERIMENTALINVESTIGATIONOFLSTBEARINGS297MAKINGTHEMODELINVALIDESPECIALLYATTHEHIGHERSPEEDANDLOWESTLOADINORDERTOBECONSISTENTWITHTHEMODELOFREF12ITWASDECIDEDTOLIMITFURTHERCOMPARISONSTOLOADSABOVE150NITSHOULDBENOTEDHERETHATTHEFIRSTATTEMPTSTOTESTTHEBASELINEUNTEXTUREDBEARINGWITHTHEORIGINALSURFACEFINISHOFRA003LMONBOTHTHESTATORANDROTORFAILEDDUETOEXTREMELYHIGHFRICTIONEVENATTHELOWERLOADSONTHEOTHERHANDTHEPARTIALLSTBEARINGRANSMOOTHLYTHROUGHOUTTHELOADRANGEITWASFOUNDTHATTHEPOSTLSTLAPPINGTOCOMPLETELYREMOVEABOUT2LMHEIGHTBULGES,WHICHAREFORMEDDURINGTEXTURINGAROUNDTHERIMSOFTHEDIMPLES,RESULTEDINASLIGHTLYROUGHERSURFACEWITHRA004LMHENCE,THEBASELINEUNTEXTUREDSTATORWASALSOLAPPEDTOTHESAMEROUGHNESSOFTHEPARTIALLSTSTATORANDALLSUBSEQUENTTESTSWEREPERFORMEDWITHTHESAMERAVALUEOF004LMFORALLTHETESTEDSTATORSTHEROTORSURFACEROUGHNESSREMAINED,THEORIGINALONENAMELY,003LMFIGURE7PRESENTSTHEEXPERIMENTALRESULTSFORTHECLEARANCEASAFUNCTIONOFTHELOADFORAPARTIALLSTUNIDIRECTIONALBEARINGSEESTATORINFIGURE4AANDABASELINEUNTEXTUREDBEARINGTHECOMPARISONISMADEATTHETWOSPEEDSOF1500AND3000RPMTHEAREADENSITYOFTHEDIMPLESINTHEPARTIALLSTBEARINGISSP06ANDTHETEXTUREDPORTIONISA0734THELOADRANGEEXTENDS575101251517520050100150200250300350400450500LOAD,NCLEARANCE,MSP06073N3000RPMN1500RPM50100150200FIGURE6ACOMPARISONOFTHETHEORETICALSOLIDLINESANDEXPERIMENTALDASHEDLINESRESULTSOFTHEBEARINGCLEARANCEVERSUSTHELOADAT1500AND3000RPM02468101214150200250300350400450500LOAD,NCLEARANCE,MSP06000734UNTEXTUREDN1500RPMN3000RPMFIGURE7ACOMPARISONOFCLEARANCEVSLOADPERFORMANCEOFPARTIALLSTUNIDIRECTIONALBEARINGANDABASELINEUNTEXTUREDBEARING298IETSIONETAL/INVESTIGATIONOFLSTPARALLELTHRUSTBEARINGSFROM160TO460NTHEUPPERLOADWASDETERMINEDBYTHETESTRIGLIMITATIONTHATDIDNOTPERMITHIGHERLOADINGITISCLEARFROMFIGURE7THATTHEPARTIALLSTBEARINGOPERATESATSUBSTANTIALLYLARGERCLEARANCESTHANTHEUNTEXTUREDBEARINGATTHEMAXIMUMLOADOF460NANDSPEEDOF1500RPMTHEPARTIALLSTBEARINGHASACLEARANCEOF6LMWHILETHEUNTEXTUREDBEARINGCLEARANCEISONLY17LMAT3000RPMTHECLEARANCESARE66AND22LMFORTHELSTANDUNTEXTUREDBEARINGS,RESPECTIVELYASCANBESEENFROMFIGURE7THISRATIOOFABOUT3INFAVOROFTHEPARTIALLSTBEARINGISMAINTAINEDOVERTHEENTIRELOADRANGEFIGURE8PRESENTSTHERESULTSFORTHEBIDIRECTIONALBEARINGSEESTATORINFIGURE4BINTHISCASETHELSTPARAMETERSARESP0614ANDA0633THECLEARANCESOFTHEBIDIRECTIONALPARTIALLSTBEARINGARELOWERCOMPAREDTOTHESEOFTHEUNIDIRECTIONALBEARINGATTHESAMELOADAT460NLOADTHECLEARANCEFORTHE1500RPMIS41LMANDFORTHE3000RPMITIS6LMTHESEVALUESREPRESENTAREDUCTIONOFCLEARANCEBETWEEN33AND10COMPAREDTOTHEUNIDIRECTIONALCASEHOWEVER,ASCANBESEENFROMFIGURE8THEPERFORMANCEOFTHEPARTIALLSTBIDIRECTIONALBEARINGISSTILLSUBSTANTIALLYBETTERTHANTHATOFTHEUNTEXTUREDBEARINGTHEFRICTIONCOECIENTOFPARTIALLSTUNIDIRECTIONALANDBIDIRECTIONALBEARINGSWASCOMPAREDWITHTHATOFTHEUNTEXTUREDBEARINGINFIGURES9AND10FORTHETWOSPEEDSOF1500AND3000RPM,RESPECTIVELYASCANBESEENTHEFRICTIONCOECIENTOFTHETWOPARTIALLSTBEARINGSISVERYSIMILARWITHSLIGHTLYLOWERVALUESINTHECASEOFTHEMOREECIENTUNIDIRECTIONALBEARINGTHEFRICTIONCOECIENTOFTHEUNTEXTUREDBEARINGISMUCHLARGERCOMPAREDTOTHATOFTHELSTBEARINGSAT1500RPMFIGURE9ANDTHEHIGHESTLOADOF460NTHEFRICTIONCOECIENTOFTHEUNTEXTUREDBEARINGISABOUT0025COMPAREDTOABOUT001FORTHELSTBEARINGSFIGURE8ACOMPARISONOFCLEARANCEVSLOADPERFORMANCEOFPARTIALLSTANDABASELINEUNTEXTUREDBIDIRECTIONALBEARINGS0005001500250035004500550065150200250300350400450500LOAD,NFRICTIONCOEFFICIENTUNTEXTUREDBIDIRECTIONALUNIDIRECTIONALFIGURE9ACOMPARISONOFFRICTIONCOECIENTOFTHEPARTIALLSTBEARINGSANDABASELINEUNTEXTUREDBEARINGAT1500RPMETSIONETAL/EXPERIMENTALINVESTIGATIONOFLSTBEARINGS299ATTHELOWESTLOADOF160NTHEVALUESAREABOUT006FORTHEUNTEXTUREDBEARINGANDAROUND002FORTHELSTBEARINGSHENCE,THEFRICTIONVALUESOFTHEUNTEXTUREDBEARINGAREBETWEEN25AND3TIMESHIGHERTHANTHECORRESPONDINGVALUESFORTHEPARTIALLSTBEARINGSOVERTHEENTIRELOADRANGESIMILARRESULTSWEREOBTAINEDATTHEVELOCITYOF3000RPMFIGURE10BUTTHELEVELOFTHEFRICTIONCOECIENTSISSOMEWHATHIGHERDUETOTHEHIGHERSPEEDTHEMUCHHIGHERFRICTIONOFTHEUNTEXTUREDBEARINGISDUETOTHEMUCHSMALLERCLEARANCESOFTHISBEARINGSEEFIGURES7AND8THATRESULTINHIGHERVISCOUSSHEAR5CONCLUSIONTHEIDEAOFPARTIALLSTTOENHANCEPERFORMANCEOFTHEPARALLELTHRUSTBEARINGWASEVALUATEDEXPERIMENTALLYGOODCORRELATIONWASFOUNDWITHATHEORETICALMODELASLONGASTHEBASICASSUMPTIONOFLAMINARFLOWINTHEFLUIDFILMISVALIDATLOWLOADSWITHRELATIVELYLARGECLEARANCES,WHERETURBULENCEMAYOCCUR,THEEXPERIMENTALCLEARANCEISLARGERTHANTHEPREDICTIONOFTHEMODELTHEPERFORMANCEOFBOTHUNIDIRECTIONALANDBIDIRECTIONALPARTIALLSTBEARINGSINTERMSOFCLEARANCEANDFRICTIONCOECIENTWASCOMPAREDWITHTHATOFABASELINEUNTEXTUREDBEARINGOVERALOADRANGEINWHICHTHETHEORETICALMODELISVALIDADRAMATICINCREASE,OFABOUTTHREETIMES,INTHECLEARANCEOFTHEPARTIALLSTBEARINGSCOM