机械毕业设计英文外文翻译554在干燥和潮湿的条件下研究高速切削的费用以及便于机械制造过程的优化.docx

机械毕业设计英文外文翻译554在干燥和潮湿的条件下研究高速切削的费用以及便于机械制造过程的优化.docx

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机械毕业设计英文外文翻译554在干燥和潮湿的条件下研究高速切削的费用以及便于机械制造过程的优化

附录1英文原文

英文原文

CHAPTERIII

COSTSTUDYOFHIGH-SPEEDCUTTINGUNDERDRYANDWETCONDITIONS

FORMACHININGPROCESSESOPTIMIZATION

3.1Introduction

Theaimofthisstudyistooptimizethemachiningprocessesbyinvestigatingtherelationshipbetweenthehighspeedmachining（HSM）andthetoollifeforthecuttingconditionsundertesting.Furthermore,studyingtheeffectofcuttingfluidontheselectedwearcriterion,andrelationshipbetweendifferentwearcriteriaandmachiningcostforthecuttinginsertsunderHSM.

Thisinvestigationshowedthatwearrateisproportionaltocuttingspeedsupportedwithsimilarobservations[12,18,19].Studyingthecorrelationbetweenhighwearratesathighcuttingspeedandmachiningcosts,providesbetterunderstandingontheperformanceofthispolicyandthebenefitofitsadoption.Currently,littleornodatahavebeenpublishedrelatingthelife-cyclecosts,toolperformance,workpiecesurfaceroughnessandworkpiecedimensionalaccuracywhenusingsolidandindexablecutters[10].However,studieshavefoundthattoolcostsinmetalcuttingmachinesareathirdofthecostofproducingparts.Thereforereducingproductcostisthefirstobjectiveofatoolmanagementsystem[16].Thebenefitsofadoptingthisresearchguidelinewillhelpdeterminetheoptimalmachiningcostandtoolreplacementpolicybasedondifferentwearcriterionvalues.Additionallythisstudyprovidesinsightinprocesscontrolandhelpsthemanagersintheearlyprocessplanningstepstoassociatefactorssuchaspreventivemaintenance,levelsofinventory,andmachiningcost.

3.2ExperimentalStudy

Thestudydevelopedaguidelineofchoosingtherightcuttingtool,cuttingspeed,andselectingtheappropriatewearcriteriaofthecuttingtoolinsertsfortheworkmaterialunderstudy.Inthisstudyvariablewearcriteriarangingfrom0.lmmto0.6mm（toollifelimit）weretakenintoconsideration.ThisexperimentwasconductedinaccordancewiththeInternationalStandardOrganizationISO36851993[46].

Thetestwasdoneona（Clausing1300）variablespindlespeedmachinewithamaximumpowerof7.5Hp（seeFigure3-1）.Thetoolwearmeasurementswereperformedusinganopticalmicroscopewithamagnificationofupto300times,andaScanningElectronMicroscope（SEM）.Therotationalspeedoftheworkpiecewasmeasuredbeforeeverycutbya（HT-5100）handhelddigitalTachometertoinsurethattheworkpiecewasaccuratelyrunningattheexactcuttingspeed.Ontheotherhand,theworkpiecematerialwasreplacedwhenthelength/diameterratioreaches10,basedonISO36851993[46],toensureworkpiecestabilityandsafety.Twoprecutwerecarriedoutwith1.2mmdepth,tocleanupthethinlayerofrust,andtoensureworkpiecestraightness.

Figure3-1Thetuningmachineusedduringthetest.

3.2.1WorkpieceandCuttingInserts

Inthisstudy,hotrolledASTM4140steelwasselectedastheworkpiecematerial.Theworkpiecepropertiesarelistedasfollows:

Description:

Hotrolledalloysteelbars,SAE4140H（UNSH4140）

Dimensions:

15cmDiameterx62.25cmlength

HeatTreatment:

Vacuumdegassed/processed,Cal-Altreated,annealedandspecialstraightened,conformingtoASTMA322andA304

Chemicalcompositions:

ThecompositionoftheworkpiecematerialislistedinTable3.1accordingtotheASTMstandards.TheexperimentwascarriedoutinaccordancewiththeinternationalstandardorganizationISO3685-93[46],theexperimentwasstoppedandtheworkpiecewaschangedwhenthelength/diameterratioreached10tomeettherequirementsofISO3685[46].Thehardnessofeachbarwascheckedacrossthediameter,andtheaveragehardnessmeasurementwas29HRC.ThetypesoftestedcuttingtoolinsertsarelistedonTable3.1accordingtotheISOdesignation.ThreetypesofcuttinginsertswereusedintheexperimentasillustratedinTable3-2;andthecoatingpropertiesarealsolistedinTable3-3.TheconfigurationoftheinvestigatedthreecuttinginsertswasthesameaslistedinTable3.4.ThegeneralcuttinginsertassembledgeometryisshowninFigure3-2.TheinsertsweremountedrigidlyonatoolholderaredepictedinFigure3-3withanISOdesignationofSVJBR2525M16.

Table3-1ChemicalcompositionofASTM4140steelusedinthetest

Cuttinginserts

ISODesignation

Substrate

Grade

Company

Uncoated

cemented

Carbide

VBMT160408

.........

KC313

Kennametal

TiAlN

VBMT160408

KC313

KC5010

Kennametal

TiN-TiCN-TiN

VBMT160408

KC313

KC732

Kennametal

Table3-2Typesofthetestedcuttinginserts

Carbon

Manganese

Phosphorus

Sulfur

Silicon

Nickel

Chromium

0.4

0.91

0.017

0.02

0.24

0.10

1.01

Tin

0.008

Aluminum

0.030

Vanadium

0.002

Calcium

0.0064

Molly

0.2

Copper

0.12

Table3-3Coatingsproperties

Coating

Thickness

Numberoflayers

TiALN

3.5µ

1

TiN-TiCN-TiN

3µ-3t-1t

3

（TiCNintermediate）

3.2.2CoolantProperties

Itisacommonbeliefthatcoolantemulsionhelpsinreducingwearrateandcuttingtemperature.Thecoolantusedinthetestwaswaterbasedemulsionhascommercialname`Novick'.Itismixedwithwaterataconcentrationof10%.ThecoolantcompositionincludesthelistedchemicalsinTable3.5.Previousresearchersonthebettercoolantstreamdirectionsmadedifferentsuggestions.Taylor[17]indicatedthattoreducetoolwearthecuttingfluidistobedirectedatthebackofthechip（directionA）.PigottandColwell[47]foundthatbyusinghighstreamjetofcoolantaimedindirectionBitwasabletoreducetoolwear.SmartandTrent[48]investigatedthedirectionofcoolantinreducingthetoolwearandfoundthatthemosteffectivedirectionbetweenallothersuggestedoptionswasdirectionB.Therefore,coolantwasappliedindirectionBaslistedinFigure3.4fromanozzlewithdiameterof1.3cmandaflowrateof7.1liters/minute.However,thecurrentstudyshowedthatthisisnotnecessarilytrueinallcasesascoolantextendsthetoollife.Itwasfoundthatcoolantemulsionhelpedreducetoollifebyactivatingcertainwearmechanismathighspeedmachining（HSM）.DetailedexplanationsofthistypeofcoolanteffectwillbediscussedinChapter5.Furthermore,abriefsummaryandexplanationoftypesandusageofcoolantwillbecoveredinChapter5.

Table3-4Assembledcuttingtoolgeometry

Toolgeometry

Dimension

Noseradius

0.8（mm）

Bakerakeangle

0°

Endreliefangle

5'

Endcutting-edgeangle

52°

Sidecutting-edgeangle

30

Siderakeangle

0'

Sidereliefangle

5'

Table3-5Coolantchemicalcompositions

Sulfate

20-30%

Aromaticalcohol

3-5%

Propyleneglycolether

3-5%

Petroleumoil

30-35%

Nonionicsurfactant

3-5%

Chlorinatedalkenepolymer

20-30%

Angulartool

Designation

Backrake0°

Siderake0°

Endrelief5°

Siderelief5°

Endcuttingedge52°

Sidecuttingedge3°

Noseradius0.88mm

Noseradius

CuttingBackrakeangle

Siderakeangle

Figure3-2Assembledtoolgeometry

Figure3-3Photographofthecuttinginsertfixedonthetoolholder

AB

Figure3-4coolantstreamdirection.

3.3CuttingConditions

BasedonI803685[46]fivecuttingspeedswereusedthroughoutthetestingaslistedonTable3-6.Cuttingspeedscorrespondingto410m/minforthecoatedcarbidetoolsand180m/minfortheuncoatedcarbidetoolswereapproximatelytheupperlimitoftheapplicationrange.Sinceanyfurtherincrementresultedinveryshortcuttingtoollifeorprematuretooldamagesoonafterthetestwasstarted.

Theturningexperimentswerecarriedoutunderdryandwetcuttingconditionsatdifferentcuttingspeeds,whilefixingbothfeedrateat0.14mm/revanddepthofcutat（1mm）.Fivecuttingspeedswereselectedforthethreetypesofcuttinginserts,aslistedinTable3-6.

3.4ExperimentalProcedureofToolLifeTesting

AClausing1300lathewithmaximum7.5HPwasusedfalloysteelSAE4140Hworkpiece,andtheturningprocesswascarriedoutinthewayortheturningoftheHotrolledpreviouslydescribed.ATachometerwasusedtomeasuretherotationalspeedbeforeeachsinglecutoccurredontheworkpieceinordertoensurethatthecuttingwasperformedattheexactspeed.

Anopticalmicroscopewasusedtomeasuretheflankwearofthecuttinginserts.Theexperimentwasterminatedifeitherofthetwofollowingconditionsoccurred

1-Themaximumflankwear0.7mmand/or;

2-Theaverageflankwear0.6mm.

Preliminaryexperimentswerecarriedoutinordertodeterminethewearlimit.Itwasfoundthatthecuttinginsertswerewornoutregularlyontheflankside.Therfore,VB,nax=0.7mm,ischosentobethewearlimitforthetoollife.Theflankwearwasobservedandmeasuredatvariouscuttingintervalsthroughouttheexperiments.Figure（3-5）showsflankwearasafunctionofcuttingtimeforthecementedcarbide（KC313）underdryandwetconditions,andincludesonlythreecuttingspeedsforclarity.

Figure3-6presentstheflankwearasafunctionofcuttingtimeforsandwichcoatedinserts（KC732）underdryandwetconditions.Figure3-7showstheflankwearasafunctionofcuttingtimeforTiALNcoatedcuttinginserts（KC5010）.Previousfiguresincludedthreecuttingspeeds.Clarityofcuttingspeedcurvesarepresentedattheattachedappendixforbothconditionsofmachining.Theaforementionedfigures,presenttheeffectofcoolantemulsioninextendingthetoollifefortheKC313,andKC732cuttinginserts;especiallyafter3minutesforKC313,andafter7minutesforKC732ofcutting.However,theusageofcoolantemulsiononKC5010showednegativeinfluence.

Figure3-5,andFigure3-6showthatatanysetofturningconditions,theflankwearincreasedatahigherratea