机械毕业设计英文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.docx

机械毕业设计英文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.docx

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机械毕业设计英文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

CHAPTERV

TOOLWEARMECHANISMSONTHEFLANKSURFACEOFCUTTINGINSERTS

FORHIGHSPEEDWETMACHINING

5.1Introduction

Almosteverytypeofmachiningsuchasturning,milling,drilling,grinding...,usesacuttingfluidtoassistinthecosteffectiveproductionofpartsassetupstandardrequiredbytheproducer[1].Usingcoolantwithsomecuttingtoolsmaterialcausesseverefailureduetothelackoftheirresistancetothermalshock（likeAL2O3ceramics）,usedtoturnsteel.Othercuttingtoolsmaterialslikecubicboronnitride（CBN）canbeusedwithoutcoolant,duetothetypeoftheirfunction.TheaimofusingCBNistoraisethetemperatureoftheworkpicetohighsoitlocallysoftensandcanbeeasilymachined.Thereasonsbehindusingcuttingfluidscanbesummarizedasfollows.

®Extendingthecuttingtoollifeachievedbyreducingheatgeneratedandasaresultlesswearrateisachieved.Itwillalsoeliminatetheheatfromtheshearzoneandtheformedchips.

®Coolingtheworkpieceofhighqualitymaterialunderoperationplaysanimportantrolesincethermaldistortionofthesurfaceandsubsurfacedamageisaresultofexcessiveheatthatmustbeeliminatedorlargelyreducedtoproduceahighqualityproduct.

Reducingcuttingforcesbyitslubricatingeffectatthecontactinterfaceregionandwashingandcleaningthecuttingregionduringmachiningfromsmallchips.Thetwomainreasonsforusingcuttingfluidsarecoolingandlubrication.

CuttingFluidasaCoolant:

Thefluidcharacteristicsandconditionofusedeterminethecoolantactionofthecuttingfluid,whichimprovestheheattransferattheshearzonebetweenthecuttingedge,workpiece,andcuttingfluid.Thepropertiesofthecoolantinthiscasemustincludeahighheatcapacitytocarryawayheatandgoodthermalconductivitytoabsorbtheheatfromthecuttingregion.Thewater-basedcoolantemulsionwithitsexcellenthighheatcapacityisabletoreducetoolwear[44].

CuttingFluidasaLubricant:

Thepurposeistoreducefrictionbetweenthecuttingedge,rakefaceandtheworkpiecematerialorreducingthecuttingforces（tangentialcomponent）.Asthefrictiondropstheheatgeneratedis

dropped.Asaresult,thecuttingtoolwearrateisreducedandthesurfacefinishisimproved.

CuttingFluidProperties

Freeofperceivableodor

Preserveclaritythroughoutlife

Kindandunirritatedtoskinandeyes.

Corrosionprotectiontothemachinepartsandworkpiece.

Costeffectiveintermsofftoollife,safety,dilutionratio,andfluidlife.[1]

5.1.1CuttingFluidTypes

Therearetwomajorcategoriesofcuttingfluids

NeatCuttingOils

Neatcuttingoilsarepoorintheircoolantcharacteristicsbuthaveanexcellentlubricity.Theyareappliedbyfloodingtheworkareabyapumpandre-circulatedthroughafilter,tankandnozzles.Thistypeisnotdilutedbywater,andmaycontainlubricityandextreme-pressureadditivestoenhancetheircuttingperformanceproperties.Theusageofthistypehasbeendecliningfortheirpoorcoolingability,causingfirerisk,proventocausehealthandsafetyrisktotheoperator[1].

®WaterBasedorWaterSolubleCuttingFluids

Thisgroupissubdividedintothreecategories:

1.Emulsion`mineralsoluble'white-milkycolorasaresultofemulsionofoilinwater.Containfrom40%-80%mineraloilandanemulsifyingagentbesidecorrosioninhibitors,besidebiocidetoinhibitthebacteriagrowth.

2.Microemulsion`semi-synthetic'inventedin1980's,haslessoilconcentrationand/orhigheremulsifierratio10%-40%oil.Duetothehighlevelsofemulsifiertheoildropletsizeinthefluidaresmallerwhichmakethefluidmoretranslucentandeasytoseetheworkpieceduringoperation.Otherimportantbenefitisinitsabilitytoemulsifyanyleakageofoilfromthemachinepartsinthecuttingfluid,acorrosioninhibitors,andbacteriacontrol.

3.Mineraloilfree`synthetic'isamixofchemicals,water,bacteriacontrol,corrosioninhibitors,anddyes.Doesnotcontainanymineraloils,andprovidesgoodvisibility

.23totheworkpiece.bareinmindthatthelackofmineraloilinthistypeofcutting

fluidneedstotakemoreattentiontomachinepartslubricationsinceitshouldnotleaveanoilyfilmonthemachineparts,andmightcausesealsdegradationduethelackofprotection.

5.1.2CuttingFluidSelection

Manyfactorsinfluencetheselectionofcuttingfluid;mainlyworkpiecematerial,typeofmachiningoperation,machinetoolparts,paints,andseals.Table5-1preparedatthemachinetoolindustryresearchassociation[2]providessuggestionsonthetypeoffluidtobeused.

5.1.3CoolantManagement

Toachieveahighlevelofcuttingfluidsperformanceandcosteffectiveness,acoolantrecyclingsystemshouldbeinstalledinthefactory.Thissystemwillreducetheamountofnewpurchasedcoolant