机械加工工艺夹具类外文文献翻译中英文翻译外文翻译.docx

机械加工工艺夹具类外文文献翻译中英文翻译外文翻译.docx

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机械加工工艺夹具类外文文献翻译中英文翻译外文翻译

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.Thissystemwillreducetheamountofnewpurchasedcoolantconcentrateandcoolantdisposable,whichwillreducemanufacturingcost.Iteitherdonebythecompanyitselforberentedout,dependsonthebudgetandmanagementpolicyofthecompany[1].

Table5-1Guidetotheselectionofcuttingfluidsforgeneralworkshopapplications.

Machining

operation

Workpiecematerial

Freemachining

andlow-

carbonsteels

Medium-

Carbonsteels

HighCarbon

andalloysteels

Stainlessand

heattreated

resistant

alloys

Grinding

Cleartypesolubleoil,semisyntheticorchemicalgrindingfluid

Turning

Generalpurpose,solubleoil,semi

syntheticorsyntheticfluid

Extreme-pressuresolubleoil,

semi-syntheticorsynthetic

fluid

Milling

General

purpose,

solubleoil,

semisynthetic

orsynthetic

fluid

Extreme-

pressuresoluble

oil,semi-

syntheticor

syntheticfluid

Extreme-pressuresolubleoil,

semi-syntheticorsynthetic

fluid（neatcuttingoilsmaybe

necessary）

Drilling

Extreme

pressuresoluble

oil,semi

syntheticor

syntheticfluid

GearShapping

Extreme-pressuresolubleoil,

semi-syntheticorsyntheticfluid

Neat-cuttingoilspreferable

Hobbing

Extreme-pressuresolubleoil,semi-syntheticor

syntheticfluid（neatcuttingoilsmaybepreferable）

Neat-cutting

oils

preferable

Bratching

Extreme-pressuresolubleoil,semi-syntheticorsyntheticfluid（neat

cuttingoilsmaybepreferable）

Tapping

Extreme-pressuresolubleoil,semi-syntheticor

syntheticfluid（neatcuttingoilsmaybenecessary）

Neat-cutting

oils

preferable

Note:

someentreisdeliberatelyextendovertwoormorecolumns,indicatingawiderangeofpossibleapplications.Otherentriesareconfinedtoaspecificclassofworkmaterial.

AdoptedfromEdwardandWright[2]

5.2WearMechanismsUnderWetHighSpeedMachining

Itisacommonbeliefthatcoolantusageinmetalcuttingreducescuttingtemperatureandextendstoolslife.However,thisresearchshowedthatthisisnotnecessarilytruetobegeneralizedovercuttinginsertsmaterials.Similarresearchwascarriedoutondifferentcuttinginsertsmaterialsandcuttingconditionssupportingourresults.Guetal[36]haverecordedadifferenceintoolwearmechanismsbetweendryandwetcuttingofC5millinginserts.Tonshoffetal[44]alsoexhibiteddifferentwearmechanismsonAL2O3/TiCinsertsinmachiningASTM5115,whenusingcoolantsemulsionscomparedtodrycutting.Inaddition,AvilaandAbrao[20]experienceddifferenceinwearmechanismsactivatedattheflankside,whenusingdifferentcoolantsintestingAL2O3lTiCtoolsinmachiningAISI4340steel.Thewearmechanismsandthebehaviorofthecuttinginsertsstudiedinthisresearchunderwethighspeed-machining（WHSM）conditionisnotfullyunderstood.Therefore,itwastheattemptofthisresearchtofocusonthecontributionsincoatingdevelopmentandcoatingtechniquesofnewlydevelopedmaterialsinordertoupgradetheirperformanceattoughmachiningconditions.Thisvaluableresearchprovidesinsightintoproductiontimesavingsandincreaseinprofitability.Costreductionsareessentialinthecompetitiveglobaleconomy;thusprotectinglocalmarketsandconsistinginthesearchofnewones.

5.3ExperimentalObservationsonWearMechanismsofUn-CoatedCementedCarbideCuttingInsertsinHighSpeedWetMachining

Inthissection,theobservedwearmechanismsarepresentedofuncoatedcementedcarbidetool（KC313）inmachiningASTM4140steelunderwetcondition.Theoverallperformanceofcementedcarbideunderusingemulsioncoolanthasbeenimprovedintermsofextendingtoollifeandreducingmachiningcost.Differenttypesofwearmechanismswereactivatedatflanksideofcuttinginsertsasaresultofusingcoolantemulsionduringmachiningprocesses.Thiswasduetotheeffectofcoolantinreducingtheaveragetemperatureofthecuttingtooledgeandshearzoneduringmachining.Asaresultabrasivewearwasreducedleadinglongertoollife.Thematerialsofcuttingtoolsbehavedifferentlytocoolantbecauseoftheirvariedresistancetothermalshock.Thefollowingobservationsrecordedthebehaviorofcementedcarbideduringhighspeedmachiningunderwetcutting.

Figure5-1showstheflanksideofcuttinginsertsusedatacuttingspeedof180m/min.TheSEMimageswererecordedafter7minutesofmachining.Itshowsmicro-abrasionwear,whichidentifiedbythenarrowgroovesalongtheflanksideinthedirectionofmetalflow,supportedwithsimilarobservationsdocumentedbyBarnesandPashby[41]intestingthrough-coolant-drillinginsertsofaluminum/SiCmetalmatrixcomposite.Sincethecuttingedgeistheweakestpartofthecuttinginsertgeometry,edgefracturestartedfirstduetotheearlynon-smoothengagementbetweenthetoolandtheworkpiecematerial.Also,thisisduetostressconcentrationsthatmightleadtoacohesivefailureonthetransientfilletedflankcuttingwedgeregion[51,52].Thesameim