1、附录附录1英文原文RollingContactBearingsTheconcernofamachinedesignerwithballandrollerbearingsisfivefoldasfollows/(a)lifeinrelationtoload；(b)stiffness/i/e/deflectionsunderload；(c)friction；(d)wear；(e)noise/Formoderateloadsandspeedsthecorrectselectionofastandardbearingonthebasisofloadratingwillbecomeimportantwh
2、ereloadsarehigh/althoughthisisusuallyoflessmagnitudethanthatoftheshaftsorothercomponentsassociatedwiththebearing/Wherespeedsarehighspecialcoolingarrangementsbecomenecessarywhichmayincreasefrictionaldrag/Wearisprimarilyassociatedwiththeintroductionofcontaminants/andsealingarrangementsmustbechosenwith
3、regardtothehostilityoftheenvironment/Becausethehighqualityandlowpriceofballandrollerbearingsdependsonquantityproduction/thetaskofthemachinedesignerbecomesoneofselectionratherthandesign/Rolling-contactbearingsaregenerallymadewithsteelwhichisthrough-hardenedtoabout900HV/althoughinmanymechanismsspecial
4、racesarenotprovidedandtheinteractingsurfacesarehardenedtoabout600HV/Itisnotsurprisingthat/owingtothehighstressesinvolved/apredominantformoffailureshouldbemetalfatigue/andagooddealofworkisbasedonacceptedvaluesoflifeanditisgeneralpracticeinthebearingindustrytodefinetheloadcapacityofthebearingasthatval
5、uebelowwhich90percentofabatchwillexceedalifeofonemillionrevolutions/Notwithstandingthefactthatresponsibilityforthebasicdesignofballandrollerbearingsrestswiththebearingmanufacturer/themachinedesignermustformacorrectappreciationofthedutytobeperformedbythebearingandbeconcernednotonlywithbearingselectio
6、nbutwiththeconditionsforcorrectinstallation/Thefitofthebearingracesontotheshaftorontothehousingsisofcriticalimportancebecauseoftheircombinedeffectontheinternalclearanceofthebearingaswellaspreservingthedesireddegreeofinterferencefit/Inadequateinterferencecaninduceserioustroublefromfrettingcorrosion/T
7、heinnerraceisfrequentlylocatedaxiallybyabuttingagainstashoulder/Aradiusatthispointisessentialfortheavoidanceofstressconcentrationandballracesareprovidedwitharadiusorchamfertoallowspaceforthis/Wherelifeisnotthedeterminingfactorindesign/itisusualtodeterminemaximumloadingbytheamounttowhichabearingwilld
8、eflectunderload/Thustheconceptof“staticload-carryingcapacity”isunderstoodtomeantheloadthatcanbeappliedtoabearing/whichiseitherstationaryorsubjecttoslightswivelingmotions/withoutimpairingitsrunningqualitiesforsubsequentrotationalmotion/Thishasbeendeterminedbypracticalexperienceastheloadwhichwhenappli
9、edtoabearingresultsinatotaldeformationoftherolling-elementdiameter/Thiswouldcorrespondtoapermanentdeformationof0/0025mmforaball25mmindiameter/Thesuccessfulfunctioningofmanybearingsdependsuponprovidingthemwithadequateprotectionagainsttheirenvironment/andinsomecircumstancestheenvironmentmustbeprotecte
10、dfromlubricantsorproductsofdeteriorationofthebearingdesign/Moreover/sealswhichareappliedtomovingpartsforanypurposeareofinteresttotribologistsbecausetheyarecomponentsofbearingsystemsandcanonlybedesignedsatisfactorilyonthebasisoftheappropriatebearingtheory/Notwithstandingtheirimportance/theamountofres
11、earcheffortthathasbeendevotedtotheunderstandingofthebehaviorofsealshasbeensmallwhencomparedwiththatdevotedtootheraspectsofbearingtechnology/LathesLathesarewidelyusedinindustrytoproduceallkindsofmachinedparts/Somearegeneralpurposemachines/andothersareusedtoperformhighlyspecializedoperations/EngineLat
12、hesEnginelathes/ofcourse/aregeneral-purposemachineusedinproductionandmaintenanceshopallovertheworld/Sizesrangefromsmallbenchmodelstohugeheavydutypiecesofequipment/Manyofthelargerlathescomeequippedwithattachmentsnotcommonlyfoundintheordinaryshop/suchasautomaticstopsforthecarriage/TracerorDuplicatingL
13、athesThetracerorduplicatinglatheisdesignedtoproduceirregularlyshapedpartsautomatically/Thebasicoperationofthislatheisasfallows/Atemplateofeitheraflatorthree-dimensionalshapeisplacedinaholder/Aguideorpointerthenmovesalongthisshapeanditsmovementcontrolsthatofthecuttingtool/Theduplicationmayincludeasqu
14、areortaperedshoulder/grooves/tapers/andcontours/Worksuchasmotorshafts/spindles/pistons/rods/caraxles/turbineshafts/andavarietyofotherobjectscanbeturnedusingthistypeoflathe/TurretLathesWhenmachiningacomplexworkpieceonageneral-purposelathe/agreatdealoftimeisspentchangingandadjustingtheseveraltoolsthat
15、areneededtocompletethework/Oneofthefirstadaptationsoftheenginelathewhichmadeitmoresuitabletomassproductionwastheadditionofmulti-toolturretinplaceofthetailstock/Althoughmostturretshavesixstations/somehaveasmanyaseight/High-productionturretlathesareverycomplicatedmachineswithawidevarietyofpoweraccesso
16、ries/Theprincipalfeatureofallturretlathes/however/isthatthetoolscanperformaconsecutiveserialsofoperationsinpropersequence/Oncethetoolshavebeensetandadjusted/littleskillisrequiredtorunoutduplicateparts/AutomaticScrewMachinesScrewmachinesaresimilarinconstructiontoturretlathes/exceptthattheirheadsarede
17、signedtoholdandfeedlongbarsofstock/Otherwise/thereislittledifferentbetweenthem/Botharedesignedformultipletooling/andbothhaveadaptationsforidenticalwork/Originally/theturretlathewasdesignedasachuckinglatheformachiningsmallcastings/forgings/andirregularlyshapedworkpieces/Thefirstscrewmachinesweredesig
18、nedtofeedbarstockandwireusedinmakingsmallscrewparts/Today/however/theturretlatheisfrequentlyusedwithacolletattachment/andtheautomaticscrewmachinecanbeequippedwithachucktoholdcastings/Thesingle-spindleautomaticscrewmachine/asitsnameimplies/machinesworkononlyonebarofstockatatime/Abar16to20feetlongisfe
19、dthroughtheheadstockspindleandisheldfirmlybyacollect/Themachiningoperationsaredonebycuttingtoolsmountedontheturretandonthecrossslide/Whenthemachineisinoperation/thespindleandthestockarerotatedatselectedspeedsfordifferentoperations/Ifrequired/rapidreversalofspindledirectionisalsopossible/Inthesingle-
20、spindleautomaticscrewmachine/aspecificlengthofstockisautomaticallyfedthroughthespindletoamachiningarea/Atthispoint/theturretandcrossslidemoveintopositionandautomaticallyperformwhateveroperationsarerequired/Afterthemachinedpieceiscutoff/stockisagainfedintothemachiningareaandtheentirecycleisrepeated/M
21、ultiple-spindleautomaticscrewmachineshavefromfourtoeightspindleslocatedaroundaspindlecarrier/Longbarsofstock/supportedattherearofthemachine/passthroughthesehollowspindlesandaregrippedbycollets/Withthesinglespindlemachine/theturretindexesaroundthespindle/Whenonetoolontheturretisworking/theothersareno
22、t/Withamultiplespindlemachine/however/thespindleitselfindexes/Thusthebarsofstockarecarriedtothevariousendworkingandsideworkingtools/Eachtooloperatesinonlyoneposition/butalltoolsoperatesimultaneously/Therefore/fourtoeightworkpiecescanbemachinedatthesametime/VerticalTurretLathesAverticalturretlatheisb
23、asicallyaturretlathethathasbeenstoodonitsheadstockend/Itisdesignedtoperformavarietyofturningoperations/Itconsistsofaturret/arevolvingtable/andasideheadwithasquareturretforholdingadditionaltools/Operationsperformedbyanyofthetoolsmountedontheturretorsideheadcanbecontrolledthroughtheuseofstops/Machinin
24、gCentersManyoftodaysmoresophisticatedlathesarecalledmachiningcenterssincetheyarecapableofperforming/inadditiontothenormalturningoperations/certainmillinganddrillingoperations/Basically/amachiningcentercanbethoughtofasbeingacombinationturretlatheandmillingmachine/Additionalfeaturesaresometimesinclude
25、dbymanufacturerstoincreasetheversatilityoftheirmachines/NumericalControlOneofthemostfundamentalconceptsintheareaofadvancedmanufacturingtechnologiesisnumericalcontrol(NC)/PriortotheadventofNC/allmachinetoolsweremanuallyoperatedandcontrolled/Amongthemanylimitationsassociatedwithmanualcontrolmachinetools/perhapsnoneismoreprominentthanthelimitationof
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