关于轴承和轴的相关知识机械外文翻译

附录一KnowledgeOnTheBearingsandShaftThebearingsarefixedandreducetheloadcoefficientoffrictionintheprocessofmechanicaltransmissioncomponents.Canalsosaythatwhentheotherpartsontheshaftrelativemotion,usedtoreducethefrictioncoefficientintheprocessofpowertransferandfixedthemechanicalpartstomaintainthepositionoftheshaftcenter.Bearingsareimportantpartsofmodernmachineryandequipment.Itsmainfunctionistosupportthemechanicalrotatingbodytoreducetheloadcoefficientoffrictionofthemechanicalequipmentinthetransmissionprocess.Accordingtothedifferentnatureoffrictionofmovingparts,bearingscanbedividedintotwotypesofrollingbearingsandplainbearings.NanoLake,Italy,foundaRomanvesseldiscoveredearlyinstanceofballbearings.Thewoodenballbearingsareusedtosupporttherotatingdesktop.Shipconstructionin40BC.ItissaidthatLeonardodaVinciinthe1500orso,aballbearingthroughdescription.,Thereisaveryimportantpointistheballcollision,causingadditionalfrictionbetweentheballbearingsofallkindsofimmaturefactors.Butcanputtheballintoasmallcagetopreventthisphenomenon.The17thcentury,Galileofixedball",or"cageball"ballbearingsdidtheearliestdescription.Butthenquitealongtime,thebearingshavebeeninstalledonthemachine.ThefirstpatentontheballchanneltheCarmarthenPhilipVaughanin1794.In1883,FriedrichFischerproposedtheideaof​​theuseofsuitableproductionmachinegrindingthesamesize,roundnessaccurateball.Thislaidthefoundationtocreateanindependentbearingindustry.In1962,FAGthetrademarkhasbeenmodifiedandarestillusedtodayandbecomeanintegralpartofthecompanyin1979.In1895,HenryTimkendesignedthefirsttaperedrollerbearings,threeyearslaterobtainedapatentandtheestablishmentoftheTimkenCompany.In1907,SKFbearingfactorySventemperatureQwestdesignedthefirstmodernself-aligningballbearings.Studyitsroleshouldbeintermsofsupport,thattheliteralinterpretationisusedtobearingaxis,butthisisonlypartofitsroleinsupportingitsessenceistobeabletobeartheradialload.Canalsobeunderstoodthatitisusedtoafixedaxis.Afixedaxissothatitcanonlyachieverotation,andcontrolofaxialandradialmovement.Motorwithoutbearingtheconsequencesisnotworkatall.Becausetheaxismaybeinanydirectionmovement,themotorworkrequirementsshaftonlyrotation.Impossibletorealizetheroleofthedrive,intheory,notonlythat,bearingalsoaffectthetransmissionmustbeachievedinordertoreducethiseffectinthehighspeedshaftbearinglubrication,andsomebearinglubrication,calledpre-lubricatedbearings,andthemostofthebearinglubricant,theloadathighspeeds,duetothefrictionwillnotonlyincreaseenergyconsumption,evenworse,isveryeasytodamagethebearing.Slidingfrictionintorollingfrictionisone-sidedtosaythingsbecauseofthekindcalledplainbearings.Bearingtheclassificationanddescribedasfollows:Equippedwithathinandlongrollerneedlebearing(thelengthoftherollerdiameterof3to10timesthediameterofgenerallynotmorethan5mm),thereforetheradialstructureiscompact,itsinnerdiameterandloadcapacitywithothertypesofbearingthesameminimumoutsidediameter,especiallyforsupportingtheresultsofradialinstallationdimensionsrestricted.needlebearingaccordingtotheuseofdifferentoccasions,canbeusedwithoutinnerringbearingsorneedlerollerandcageassemblyandbearingtomatchthejournalsurfacedirectlyasabearingsurfaceandshellholes,outerrollingsurfaceinordertoensuretheloadcapacityandrunningperformancewitharingbearingthesameshaftorshellholesontheracewaysurfaceofthehardness,themachiningaccuracyandsurfacequalityshouldbethebearingrings.useCombinedneedlerollerbearingstotheheartneedlerollerbearingsandthrustbearingpartsbearingunitsofthecombinationofitscompactsize,small,highprecisionrotation,canwithstandhighradialloadtobearcertainaxialload.Andtheproductstructureinvariousforms,wideadaptability,easytoinstall.Combinedneedlerollerbearingsarewidelyusedinmachinetools,metallurgicalmachinery,textilemachinery,printingmachineryandothermachineryandequipment,andmakethemechanicalsystemdesignisverycompactandnimble.AligningballbearingsSelf-aligningballbearings:twooftheinnerringracewayandtheracewaybetweenthesphericalouterring,theassemblyofthedrum-shapedrollerbearing.Theouterringracewaycurvaturecenterandbearingcenterline,andthereforehavethesamealigningandself-aligningballbearings.Axis,theshelldeflectionoccurs,youcanautomaticallyadjusttonotincreasetheburdenofbearing.Sphericalrollerbearingscanbearradialloadandaxialloadintwodirections.Aligningballbearingradialloadcapacity,suitableforaheavyimpactloadconditions.Theinnerdiameteristaperedborebearingscanbeinstalleddirectly.Orusetheadaptersleeve,removethetubeinstalledinthecylinderaxis.Cagetheuseofsteelstampingcage,formingpolyamide-aligningballbearingswithstandheavyloadsandimpactloads,precisioninstruments,lownoisemotors,automobiles,motorcycles,metallurgy,mill,mining,petroleum,paper,cement,pressedsugarindustryandthegeneralmachinery.Deepgrooveballbearingsimportedbearingsaremainlyusedforpureradialload,bothradialandaxialload.Onlyunderpureradialload,thecontactangleiszero.Performanceofangularcontactbearings,deepgrooveballbearingswithalargerradialclearance,andissubjectedtohighaxialload.Deepgrooveballbearings,thefrictioncoefficientissmall,thelimitspeedisalsohigh,especiallyinalargehigh-speedoperationoftheaxialloadconditions,deepgrooveballbearingsThrustballbearingsaremoreadvantages.Deepgrooveballbearingsarethemostrepresentativeoftherollingbearings,widelyused.Forhighspeedorhighspeedoperation,andisverydurable,withoutregularmaintenance.Theclasshasasmallcoefficientoffriction,highlimitingspeed,simplestructure,lowmanufacturingcost,easytoachievehighmanufacturingprecision.Sizerangeanddiversity,changesintheformusedinprecisioninstruments,lownoisemotors,automobiles,motorcyclesandgeneralmachineryandotherindustries,isthemachineryindustry'smostwidelyusedtypeofbearings.Themainradialload,andcanwithstandacertainamountofaxialloaddeepgrooveballbearingscanbeusedforthetransmission,instrumentation,motors,appliances,internalcombustionengines,transportationvehicles,agriculturalmachinery,constructionmachinery,constructionmachineryandsoon.Aligningrollerbearingisasphericalouterringbetweenthetworacewaysoftheinnerringracewayassemblywithdrum-shapedrollerbearings.Aligningrollerbearingwithtworollers,mainlyexposedtothediameterofaload,butalsoabletowithstandtheaxialloadineitherdirection.Highradialloadcapacity,especiallysuitableforworkoverloadorvibrationloads,butcannotaffordthepureaxialload.Thiskindofbearingouterringracewayissphericalshape,aligningperformanceisgood,cancompensateconcentricityerror.Sphericalrollerbearingshavetwosymmetricalsphericalrollerouterringofacommonsphericalraceway,twobearingaxisofinnerringtiltangleoftheraceway,hasagoodaligningproperties,whentheaxisforcebearingwhenbendingorinstalladifferenthearttocontinueitsnormaluse,tuneconcentricwiththebearingdimensionseriesvary,generallyallowaligningangleof2.5degrees,thetypeofloadbearingcapacity,inadditiontoradialloadsTheouterbearingscanwithstandaxialloadofthetwo-wayrole,withgoodimpactresistance,ingeneral,self-aligningrollerbearingsallowedspeedislow.Sphericalrollerbearingsaccordingtothesectionshapeoftherollerisdividedintotwodifferentstructuresofthesymmetricalsphericalrollerandnon-symmetricalsphericalroller,asymmetricself-aligningrollerbearingsareearlyproducts,mainlythehostrepairservices,newdesignhostrarelyusesymmetricalself-aligningrollerbearings,theinternalstructureoftheoverallimprovementofthedesignandparametersoptimization,thanwiththeearlyproductionofaligningrollerbearings,abletowithstandgreateraxialload,thisbearingrunlowertemperatures,itcanadapttotherequirementsofhighspeed,accordingtowhethertheinnerribandcagecanbedividedintotwokindsofCandCA,C-typebearingischaracterizedbytheinnerwallandtheuseofsteelstampingframe,theCA-bearingcharacteristicsfortheinnerringonbothsideshaveribsmachinedsolidcageinordertoimprovethelubrication,canprovideuserswiththeouterringwithacirculartank,andthreeholeSphericalrollerbearings,setthecodetothebearings/W33canalsosupplyaccordingtotherequirementsofuserswiththeinnerholeofthealigningrollerbearings,inordertofacilitatecustomerhandlingandreplacementofbearings,canalsobeprovidedwithintheholewithataperaligningrollerbearings,bearings,taperedbore,taper1:12aftertheset,code-namedK,inordertoadapttospecificuserrequirementscanalsobeprovidedwithinthetaperbearingsof1:30,followedbytheset,code-namedK30holewithThetaperofthebearingcanbeusedlocknutbearingmountedontheconicaljournal,butalsocanmakeuseoftheadaptersleeveorwithdrawalsleevebearingsinstalledinthecylindricaljournal.Combinationofbearing:abearingformedbythecombinationofbearingstructureintheabove-mentionedtwoormoreofrollingbearings.Suchasneedlerollerandcylindricalrollerthrustbearings,needlerollerandthrustballbearings,needlerollerandangularcontactballbearings,etc..Bearinglife:undercertainloads,thebearingsinthenumberofrevolutionsorhoursbeforepittingexperienced,knownasthebearinglife.Thelifeofrollingbearingsofthenumberofrevolutions(ornumberofhoursworkedunderacertainspeed)isdefined:Inthislifewithinthebearing,anybearingringorrollingbodyontheinitialfatiguedamage(spallingordefect).Butbothinthelaboratorytestsorinactualuse,canclearlyseetheappearanceofthesamebearinginthesameworkingconditions,todiffermateriallyfromactuallife.Inadditiontothebearingofseveraldifferentdefinitionsof"life",oneoftheso-called"workinglife",itmeansthattheactuallifeofabearingcanbeachievedbeforethedamagefromthewearandtear,damageisusuallynotcausedbyfatigue,butcausedbywearandtear,corrosion,sealdamage.Duetodifferencesinmanufacturingprecision,materialuniformity,evenifthesamematerial,bearingthesamebatchofthesamesize,inthesameworkingconditions,theirlongevityisnotthesame.Intermsofstatisticallifeis1unitrelativelifeexpectancyofuptofourunits,theshortestwas0.1to0.2units,theratioofthelongestandshortestlifeof20to40times.Theinstallationofbearings:Bearinginstallation,goodorbad,willaffecttheaccuracy,bearinglifeandperformance.,Theinstallationofthebearing,inaccordancewiththeoperatingstandardsincludethefollowingitems,includingthebearinginstallation.①cleaningbearingsandrelatedpartshavebeengreasedbearingsandbilateralwithsealsordustcover,noneedtocleanbeforetheinstallationoftheringbearing.②Checkthesizeandfinishingconditionsoftherelevantpartsofthe③installationmethodbearinginstallationshouldbebasedonthenatureofthebearingstructure,size,andbearingcomponentswithpressureshouldbedirectlyaddedtoatightfittotheferruleendsurface,maynotpassthepressureoftherollingelementbearinginstallationgenerallyusethefollowingmethod:apress-fitbearinginnerringandshaftsotightfit,theouterringandthebearingholeisloosewiththeavailablepresseswillbebearingthefirstpressuremountedontheshaftandtheshafttogetherwiththebearingwithloadbearingholepress-fitbearinginnerringsidesurface,padassemblysleeveofasoftmetalmaterial(copperormildsteel),theassemblycasingdiametershouldbeslightlylargerthanthejournaldiameter,thediameteroftheouterdiameterthanthebearinginnerringribsslightlysmaller,inordertoavoidpressureinthecage.Thebearingouterringandthebearingholeisatightfit,theinnerringandtheshaftisloosewiththebearingfirstpressedintothebearinghole,thistimetheassemblycasingoutsidediametershouldbeslightlysmallerthanthediameterofthebore.Ifthebearingringandshaftandhousingboreareatightfittoinstalltheindoorringandouterringtobepressedintotheshaftandhousingbore,theassemblystructureofthecasingshouldbeabletochargetightendfaceofthebearinginnerandouterrings.(b)heatingwithheatedbearingsorbearing,theuseofthermalexpansionwillbeatightfittochangetheinstallationmethodforaloosefit.④bearinginstallationinspection⑤lubricantaddedtotheinstallationofhigh-speedprecisionangularcontactballbearings,mainlyfortheloadlighter,high-speedrotatingoccasions,therequirementofbearinghigh-precision,highspeed,lowtemperatureriseLowvibrationandservicelifeofhigh-speedprecisionangularcontactballbearings.Oftenforhigh-speedelectricspindlebearinginstalledinpairs,thekeycomponentpartsoftheinnersurfaceofthegrindingmachineofhighspeedelectricspindle.Themaintechnicalindicators:1.Bearingaccuracyspecifications:morethanGB/307.1-94theP4levelprecisionhigh-speedperformance:dmNvalueof1.3~1.8x106/min3.Life(average):>1500hLifeofhigh-speedprecisionangularcontactballbearingshaveagreatrelationshipwiththeinstallation,youshouldnotethefollowing:①Thebearingsshallbeinstalledinaclean,cleanroom,bearingcarefullymatching,bearingspacerstogothroughgrinding,maintainingthepremiseofhigh-insideandoutsidetheringspacers,spacerparallelismshouldbecontrolledin1umfollowing;②Thebearingspriortoinstallationshouldbeclean,cleaninginnerslopesupward,shouldbeflexibleandfeelnosenseofstagnation,driedandputintothespecifiedamountofgrease,inthecaseofoilmistlubricationshouldbeplacedinasmallamountofoilmistoil;③bearinginstallationshouldbeusedspecializedtools,evenbyforce,strictlyprohibitedbeating;④Thebearingsshallbestoredincleanair,corrosivegases,relativehumidityofnotmorethan65%long-termstorageshouldbeperiodicallyrust-proof.Taperedrollerbearings,waterpumpbearinginstallation:①theinstallationofbearings:bearingmustbeinstalledinadry,cleanenvironmentconditions.Beforeinstallation,carefullycheckthematingsurfaceoftheshaftandshell,thefaceoftheconvexshouldertrenchandconnectionqualityofsurfaceprocessing.Allmatchtheconnectedsurfacemustbecarefullycleanedandremovetheburrs,castingrawsurfacemustbeinadditiontonetsand.Bearinginstallationshouldbeprecededbycleaningwithgasolineorkerosene,cleananddrybeforeuse,andtoensuregoodlubrication,bearingsarecommonlyusedgreaselubrication,oillubricationcanbeused.Withgreaselubricationshouldbeusedfreeofimpurities,anti-oxidation,rustandextremepressureperformancesuperiorgrease.Thegreasefillingis30%to60%ofthebearingsandthebearingcapacityofthecontainer,nottoomuch.Withsealingstructureofthedoublerowtaperedrollerbearingsandpumpshaftbearingfilledagoodgrease,userscandirectlyuse,notforcleaning.Bearinginstallation,youmustexertequalpressureonthecircumferenceoftheferruleendfacepressedintotheringnotwantfirst-classtoolstotapthebearingface,soasnottodamagethebearing.Smallamountofinterferencewiththesleeveatroomtemperature,pressandholdthebearingringfacehammertobeatthesleevethroughthesleeveringsevenlypressedinto.Iflargequantitiesofinstallationcanbeahydraulicpress.②bearingremoval:Removethebearingintendtocontinuetouse,youshouldusetheappropriateremovaltool.Thedemolitionoftheinterferencefitofthering,onlytoincreasethetensioninthering,nevertoallowdemolitionoftherollingelements,ortherollingelementandracewaywillbecrushed.③bearinguseoftheenvironment:theuseoflocationandconditionsofuseandenvironmentalconditionstoselectthespecificationsofsize,accuracy,andwiththerightbearingisthepremisetoensurethatthebearinglifeandreliability.Parts:taperedrollerbearingsaresuitabletowithstandtheradialloadmainlyradialandaxialjointload,usuallypairedtotwosetsofbearingsusedprimarilyinthecar'sfrontandrearwheelhub,activebevelgear,differential,reducerandtransmissionparts.Allowablespeed:correctlyinstalled,well-oiledenvironment,allowingthebearinglimitspeedof0.3to0.5times.Undernormalcircumstances,thelimitof0.2timesthespeedofthemostsuitable.Allowtheangleofinclination:taperedrollerbearingsaregenerallynotallowedaxisoftherelativeshellholetilt,wheretiltmaximumofnotmorethan2'.Allowthetemperature:underthenormalload,thelubricanthashightemperatureresistance,andadequatelubricationconditions,thegeneralbearingallowstoworkin-30°Cto150°Cambienttemperature.Axisfunctionandtype:Axisisoneoftheimportantpartsinthemachine,usedtosupporttherotatingpartsofmachinery.Dependingontheloadbearingaxiscanbedividedintotheshaft,driveshaftandspindlethreekinds.Shaftonlytransfertorquetowithstandbendingmoments,suchasthegearreducershaft;driveshafttransmittingtorqueonlynotwithstandthebendingmomentorbendingmomentissmall.Suchasautomotivedriveshaft;spindleisexposedonlytothemomentratherthantransmittorque,suchastheaxisoftherailvehicle,thefrontaxleofthebicycle.Theshapeoftheshaftaxiscanbedividedinto:straightaxle,crankshaftandflexiblewireaxis.Crankshaftiscommonlyusedinreciprocatingmachinery.Theflexiblewireshaftwirelayersclosetogetherbylayersofflexibletorqueandrotationalmovementspreadtoanylocationcommonlyusedinvibratorsandotherdevices.Thischapteronlystudythedirectaxis.

Shaftdesign,manufacturingprocessaccordingtojobrequirementsandtoconsiderotherfactors,theappropriatechoiceofmaterials,structuraldesign,throughstrengthandstiffness,settheaxisofthestructureshapeandsize,ifnecessary,considerthevibrationstability.Axisofthecommonlyusedmaterials:Theaxisofthematerialisoftenusedcarbonsteelandalloysteel.Carbonsteelbearing35,45,50high-qualitycarbonstructuralsteelhashighermechanicalproperties,moreapplications,ofwhichthemostwidelyusedsteel45.Inordertoimproveitsmechanicalproperties,normalizingorquenchingandtemperingtreatment.Unimportant,orbyasmallerforceaxis,canbeusedsuchasQ235,Q275carbonstructuralsteel.Alloysteelalloysteelhashighermechanicalproperties,butthepriceismoreexpensive,usedforspecialrequirementsoftheshaft.Forexample:theslidingbearingsofhigh-speedshaft,commonlyusedin20Cr,20CrMnTilow-carbonalloystructuralsteelaftercarburizingcanimprovethewearresistanceofthejournal;generatorrotorshaftinthehightemperature,high-speedandoverloadconditions.musthavegoodhightemperaturemechanicalproperties,oftentoadopt40CrNi,38CrMoAlAalloystructuralsteel.Itisworthnoting:thetypeandheattreatmentofsteel,itselasticmodulusisverysmall.Foruseofalloysteelorheattreatmenttoimprovetheshaftstiffnessisnopracticalresults.Inaddition,thealloysteelhighersensitivitytostressconcentration,alloysteelshaftdesign,moreshouldbestructuredtoavoidorreducethestressconcentrationandreducethesurfaceroughness.Axisroughgeneralroundbarorforgings,andsometimescanbecastorductileiron.Forexample,madeofnodularcastironcrankshaft,camshaft,lowcost,bettervibrationabsorption,lowsensitivitytostressconcentration,goodstrength,etc..Axisofstructuraldesign:Theaxisofthestructuredesignistomakeeachpartoftheaxishasareasonableshapeandsize.Itsmainrequirementsare:1)axisshouldbeeasyprocessing.Partsoftheshafttobeeasydisassembly(manufactureandinstallationrequirements);2)axisandtheshaftpartshaveaccurateposition(location);3)partstofirmlyandreliablyandrelativelyfixed(fixed);4)toimprovetheforcesituation,reducingthestressconcentration.①ThemanufacturinginstallationrequirementsInordertofacilitatetheassemblyanddisassemblyoftheshaftparts,oftentheshaftmadeoftheladder.Splittheboxintheshaft,itsdiameterfromtheshaftendandgraduallyincreasestowardthemiddle.Asshownabove,canturnthegear,thesleeve,theleftendbearings,bearingcapsandpulleyfromtheaxisoftheleftendassemblyanddisassembly,andanotherfromtherightendoftheassemblyanddisassemblyofrollingbearings.Shaftpartsiseasytoinstall,shouldchamferoftheshaftendandtheendoftheshaftsection.Axisgrindingshaftsectionshouldwheelthemoreprocessslots;carthreadedshaftsectionshouldbeundercut.Meettherequirementsofthecase,theaxisoftheshapeandsizeshouldbesimpleinordertofacilitateprocessing.②TheaxispositioningofpartsLaddershaftcross-sectionchangesaplacecalledtheshaftshoulder,sincetheaxialpositioningoftherole.Shaftshouldermakesgearpositionedontheshaft;shaftshoulderpulleypositioning;shaftshouldertotherightendoftherollingbearingpositioning.Somepartsrelyonasetofsimplepositioning,suchasabovetheleftendofrollingbearings.③TheaxispartsofthefixedAxialfixationoftheshaftparts,oftenwiththeshaftshoulder,sleeve,nutorshaftendoftheretainingring(alsoknownastheplate)andotherforms.Geartoachievetheaxialtwo-wayfixed.Gearbytheaxialforce,rightthroughtheshaftshoulder,bytheaxisandshouldersintherollingbearinginnerring;leftsleevetopintherollingbearinginnerring.Cannotusethesleeveorsleevestoolong,wecanusetheroundnuttobefixed.Pulleyaxialfixedretainingringdependontheshaftshoulderandtheshaftend.Axisintensitycalculatedasfollows:Axisintensityshallbecalculatedaccordingtotheshaftbearing,usingtheappropriatemethodofcalculation.Thecommonaxisstrengthcalculationmethodhasthefollowingtwo:①PressthetorsionalstrengthcalculationThismethodappliesonlytowithstandthetorqueofthedriveshaftofaccuratecalculation,iswellreceivedbythebendingmomentandtorqueaxisapproximatecalculationcanalsobeused.

Circularsectionshafttransmittingtorqueonly,thestrengthcondition.Withstandbothpasstoturnshortaxisofthebendingmomentcanalsobeusedonthepreliminaryestimateofthediameterofthedesignformula:Inaddition,theempiricalformulacanbeusedtoestimatethediameteroftheshaft.Forexample,inthegeneralreducer,high-speedinputshaftdiameteraccordingtoitsassociatedmotorshaftdiameterDestimates,d=(0.8~1.2)D;alllevelsoflow-speedshaftofthegearcenterdistanceontheshaftdiameteraccordingtothesamelevelaestimates,d=(0.30.4)a.②AccordingtothesyntheticstrengthofthebendingandtorsionSingle-stagecylindricalgearreducerdesignsketches,eachsymbolindicatesthelengthoftheDimensions.Obviously,whenthepartslaidoutonthesketch,theroleoflocationoftheexternalloadandsupportreactionforcecanbedetermined.Thuscanbeusedformechanicalanalysisoftheshaftanddrawthebendingmomentdiagramandtorquediagram.Thenyoucanpressthesyntheticstrengthofthebendingandtorsionshaftdiameter.Forthecross-sectionofthekeywayshouldbecalculatedshaftdiameterincreasedbyabout4%.Calculatedshaftdiametergreaterthantheshaftdiameterofpreliminaryestimatesofthestructuraldesign,thatthestrengthofthechartaxisisnotenough,youmustmodifythestructuraldesign;calculatedshaftdiameterlessthantheestimatesofthestructuraldesignofshaftdiameter,andthedifferenceisnotverygenerallysubjecttothestructuraldesignoftheshaftdiameter.

Forgeneral-purposeshaftdesignedbytheabovemethodcan.Importantaxis,yetfurtherstrengthcheck(suchasthesafetyfactormethod),thecalculationmethodavailableatthereference.

Shaftstiffnesscalculatedasfollows:Axisbythebendingmomentwillproduceabendingtorquerolewillhavethetorsionaldeformation.Iftheshaftstiffnessisnotenough,itwillaffectthenormalworkoftheaxis.Forexample,thedeflectionoftherotorshaftistoolarge,willchangetherotorandstatorgapandaffecttheperformanceofthemotor.Anotherexampleistherigidityofthemachinespindleisenough,itwillaffectthemachiningaccuracy.Therefore,inordersothattheaxisisnotenoughstiffnessandfailure,mustbedesignedtolimittheirworkingconditionsundertheshaftdeformationAxisoftheconceptofcriticalspeed:Unevenduetostructuralasymmetriesoftherotaryparts,materials,processingerrorsandotherreasons,tomaketherotationcenterofgravityispreciselylocatedinthegeometricaxis,itisalmostimpossible.Infact,thecenterofgravityandthegeometricaxisgenerallytotalaslighteccentricity,andthusthecentrifugalforcegeneratedwhenrotatingtheaxisbytheinterferenceofcyclicalloading.Axissufferedexternalfrequencyaxissincethevibrationfrequencyofthesameoperationwillbeunstablevibrationoccurs,aphenomenonknownastheresonanceoftheshaft.Resonancewhentheshaftspeediscalledthecriticalspeed.Iftheshaftspeedisstucknearthecriticalspeed,theaxisofdeformationincreasesrapidly,aswellastheaxis,theextentofthedamageoreventhewholemachine.Therefore,theimportant,especiallyhigh-speedaxistocalculatethecriticalspeed,andshaftspeedntoavoidthecriticalspeednc.Theshaftcriticalspeed,thelowestonecalledthefirstcriticalspeed,theremainingsecond,third......Speed​​isbelowafirstcriticalspeedaxisis