外文翻译--在高速潮湿机械加工条件下后刀面表层磨损机理.doc

11CHAPTERVTOOLWEARMECHANISMSONTHEFLANKSURFACEOFCUTTINGINSERTSFORHIGHSPEEDWETMACHINING5.1IntroductionAlmosteverytypeofmachiningsuchasturning,milling,drilling,grinding.,usesacuttingfluidtoassistinthecosteffectiveproductionofpartsassetupstandardrequiredbytheproducer1.Usingcoolantwithsomecuttingtoolsmaterialcausesseverefailureduetothelackoftheirresistancetothermalshock(likeAL2O3ceramics),usedtoturnsteel.Othercuttingtoolsmaterialslikecubicboronnitride(CBN)canbeusedwithoutcoolant,duetothetypeoftheirfunction.TheaimofusingCBNistoraisethetemperatureoftheworkpicetohighsoitlocallysoftensandcanbeeasilymachined.Thereasonsbehindusingcuttingfluidscanbesummarizedasfollows.®Extendingthecuttingtoollifeachievedbyreducingheatgeneratedandasaresultlesswearrateisachieved.Itwillalsoeliminatetheheatfromtheshearzoneandtheformedchips.®Coolingtheworkpieceofhighqualitymaterialunderoperationplaysanimportantrolesincethermaldistortionofthesurfaceandsubsurfacedamageisaresultofexcessiveheatthatmustbeeliminatedorlargelyreducedtoproduceahighqualityproduct.Reducingcuttingforcesbyitslubricatingeffectatthecontactinterfaceregionandwashingandcleaningthecuttingregionduringmachiningfromsmallchips.Thetwomainreasonsforusingcuttingfluidsarecoolingandlubrication.CuttingFluidasaCoolant:Thefluidcharacteristicsandconditionofusedeterminethecoolantactionofthecuttingfluid,whichimprovestheheattransferattheshearzonebetweenthecuttingedge,workpiece,andcuttingfluid.22Thepropertiesofthecoolantinthiscasemustincludeahighheatcapacitytocarryawayheatandgoodthermalconductivitytoabsorbtheheatfromthecuttingregion.Thewater-basedcoolantemulsionwithitsexcellenthighheatcapacityisabletoreducetoolwear44.CuttingFluidasaLubricant:Thepurposeistoreducefrictionbetweenthecuttingedge,rakefaceandtheworkpiecematerialorreducingthecuttingforces(tangentialcomponent).Asthefrictiondropstheheatgeneratedisdropped.Asaresult,thecuttingtoolwearrateisreducedandthesurfacefinishisimproved.CuttingFluidPropertiesFreeofperceivableodorPreserveclaritythroughoutlifeKindandunirritatedtoskinandeyes.Corrosionprotectiontothemachinepartsandworkpiece.Costeffectiveintermsofftoollife,safety,dilutionratio,andfluidlife.15.1.1CuttingFluidTypesTherearetwomajorcategoriesofcuttingfluidsNeatCuttingOilsNeatcuttingoilsarepoorintheircoolantcharacteristicsbuthaveanexcellentlubricity.Theyareappliedbyfloodingtheworkareabyapumpandre-circulatedthroughafilter,tankandnozzles.Thistypeisnotdilutedbywater,andmaycontainlubricityandextreme-pressureadditivestoenhancetheircuttingperformanceproperties.Theusageof33thistypehasbeendecliningfortheirpoorcoolingability,causingfirerisk,proventocausehealthandsafetyrisktotheoperator1.®WaterBasedorWaterSolubleCuttingFluidsThisgroupissubdividedintothreecategories:1.Emulsionmineralsolublewhite-milkycolorasaresultofemulsionofoilinwater.Containfrom40%-80%mineraloilandanemulsifyingagentbesidecorrosioninhibitors,besidebiocidetoinhibitthebacteriagrowth.2.Microemulsionsemi-syntheticinventedin1980s,haslessoilconcentrationand/orhigheremulsifierratio10%-40%oil.Duetothehighlevelsofemulsifiertheoildropletsizeinthefluidaresmallerwhichmakethefluidmoretranslucentandeasytoseetheworkpieceduringoperation.Otherimportantbenefitisinitsabilitytoemulsifyanyleakageofoilfromthemachinepartsinthecuttingfluid,acorrosioninhibitors,andbacteriacontrol.3.Mineraloilfreesyntheticisamixofchemicals,water,bacteriacontrol,corrosioninhibitors,anddyes.Doesnotcontainanymineraloils,andprovidesgoodvisibility.23totheworkpiece.bareinmindthatthelackofmineraloilinthistypeofcuttingfluidneedstotakemoreattentiontomachinepartslubricationsinceitshouldnotleaveanoilyfilmonthemachineparts,andmightcausesealsdegradationduethelackofprotection.5.1.2CuttingFluidSelectionManyfactorsinfluencetheselectionofcuttingfluid；mainlyworkpiecematerial,typeofmachiningoperation,machinetoolparts,paints,andseals.Table5-1preparedatthemachinetoolindustryresearchassociation2providessuggestionsonthetypeoffluidtobeused.445.1.3CoolantManagementToachieveahighlevelofcuttingfluidsperformanceandcosteffectiveness,acoolantrecyclingsystemshouldbeinstalledinthefactory.Thissystemwillreducetheamountofnewpurchasedcoolantconcentrateandcoolantdisposable,whichwillreducemanufacturingcost.Iteitherdonebythecompanyitselforberentedout,dependsonthebudgetandmanagementpolicyofthecompany1.Table5-1Guidetotheselectionofcuttingfluidsforgeneralworkshopapplications.MachiningoperationWorkpiecematerialFreemachiningandlow-carbonsteelsMedium-CarbonsteelsHighCarbonandalloysteelsStainlessandheattreatedresistantalloysGrindingCleartypesolubleoil,semisyntheticorchemicalgrindingfluidTurningGeeralprpose,solubleoil,semisyntheticorsyntheticfluidExtreme-pressuresolubleoil,semi-syntheticorsyntheticfluidMillingGeneralpurpose,solubleoil,semisyntheticorsyntheticfluidExtreme-pressuresolubleoil,semi-syntheticorsyntheticfluidExtreme-pressuresolubleoil,semi-syntheticorsyntheticfluid(neatcuttingoilsmaybenecessary)DrillingExtreme-pressuresolubleoil,semi-syntheticorsyntheticfluidGearShappingExtreme-pressuresolubleoil,semi-syntheticorsyntheticfluidNeat-cuttingoilspreferable