铝基复合材料超精密加工中的刀-屑摩擦磨损性能及模型研究

铝基复合材料超精密加工中的刀-屑摩擦磨损性能及模型研究Abstract

Aluminum-basedcompositematerialshavebeenwidelyusedinmanyindustriesduetotheirexcellentmechanicalproperties.However,intheultra-precisionmachiningprocess,tool-chipfrictionalwearisoneofthemostcriticalfactorsaffectingthemachiningqualityandcuttingefficiency.Inthisstudy,thefrictionalwearperformanceandmodelofthetool-chipinterfaceduringtheultra-precisionmachiningofaluminum-basedcompositematerialswereinvestigated.Theresultsshowedthatthetool-chipfrictionalwearincreasedwiththeincreaseofcuttingspeedandfeedrate.Thetool-chipinterfacetemperatureandthecontactpressurewerethemainfactorsaffectingthefrictionalwear.AmodeloffrictionalwearwasdevelopedbasedontheArchard'swearlawandthefiniteelementanalysis,whichcanpredictthetool-chipfrictionalwearwithhighaccuracy.Theexperimentalandsimulationresultsrevealedthatthedevelopedmodelcanprovideimportantguidanceforselectionofcuttingparametersandoptimizationoftooldesignintheultra-precisionmachiningofaluminum-basedcompositematerials.

Introduction

Aluminum-basedcompositematerialshavebeenwidelyusedinvariousindustriesduetotheirexcellentmechanicalproperties,suchashighstrength-to-weightratio,goodcorrosionresistanceandlowcoefficientofthermalexpansion.However,intheultra-precisionmachiningprocess,thetool-chipfrictionalwearisoneofthemostcriticalfactorsaffectingthemachiningqualityandcuttingefficiency.Theexcessivetool-chipfrictionalwearcanleadtounacceptablesurfaceroughnessandtooldamage,whichcangreatlyreducethemachiningaccuracyandefficiency.Therefore,itisessentialtoinvestigatethetool-chipfrictionalwearpropertiesanddevelopanaccuratewearmodelfortheultra-precisionmachiningofaluminum-basedcompositematerials.

ExperimentalProcedure

Thealuminum-basedcompositematerialusedinthisstudywasAl-SiCp,whichiscomposedof15%byvolumeofSiCparticleswithanaveragediameterof25μm.Theultra-precisionturningexperimentswereconductedonaCNClathewithaPCDtoolinsert.Thecuttingspeedsrangedfrom20m/minto80m/min,andthefeedratesrangedfrom0.05mm/revto0.2mm/rev.Thecuttingdepthwasfixedat0.1mm,andthemachiningtimewassetas60seconds.Thefrictionalwearofthetool-chipinterfacewasmeasuredusinga3Dsurfaceprofilometer.

ResultsandDiscussion

Theexperimentalresultsshowedthatthetool-chipfrictionalwearincreasedwiththeincreaseofcuttingspeedandfeedrate.Figure1showsthe3Dsurfaceprofilometerimagesofthetool-chipinterfaceunderdifferentcuttingconditions.Itcanbeobservedthatthetool-chipfrictionalwearwasmoresevereathighercuttingspeedsandfeedrates.Theincreaseoffrictionalwearcanbemainlyattributedtotheincreasedtemperatureandcontactpressureatthetool-chipinterface.

Toinvestigatethemechanismofthetool-chipfrictionalwearanddevelopanaccuratewearmodel,afiniteelementanalysis(FEA)wasperformedusingthecommercialsoftwareABAQUS.Thetool-chipinteractionmodelwasestablishedasshowninFigure2,wherethePCDtoolinsertwasmodeledasrigidandthechipwasmodeledasdeformable.Thecontactconditionswereassumedtobepressure-dependentandtemperature-dependentfrictionalcontactwithafrictioncoefficientof0.5.Theinitialtemperatureandtheheattransfercoefficientbetweenthetoolandthechipweresetas300Kand1000W/m2·K,respectively.

Thesimulationresultsshowedthatthetool-chipinterfacetemperatureandthecontactpressurewerethemainfactorsaffectingthefrictionalwear.Figure3showsthetemperaturedistributionofthetool-chipinterfaceunderdifferentcuttingconditions.Itcanbeobservedthatthetemperatureincreasedsharplynearthetool-chipinterface,andthemaximumtemperatureincreasedwiththeincreaseofcuttingspeedandfeedrate.Moreover,thetemperaturedistributionwasasymmetricduetothenon-uniformityofthechipthicknessandthecuttingforces.Therefore,thetool-chipinterfacetemperatureshouldbeconsideredinthewearmodel.

TheArchard'swearlawwasusedtomodelthetool-chipfrictionalwear,whichassumesthatthewearrateisproportionaltothecontactpressureandslidingdistancebetweenthetoolandthechip.ThewearmodelwasthenintegratedintotheFEAmodel,andthetool-chipfrictionalwearwaspredicted.Figure4showsthecomparisonbetweentheexperimentalandsimulationresultsofthetool-chipfrictionalwearunderdifferentcuttingconditions.Itcanbeobservedthatthesimulationresultsagreedwellwiththeexperimentalresults,whichvalidatedtheaccuracyofthedevelopedwearmodel.

Conclusion

Inthisstudy,thefrictionalwearperformanceandmodelofthetool-chipinterfaceduringtheultra-precisionmachiningofaluminum-basedcompositematerialswereinvestigated.Theresultsshowedthatthetool-chipfrictionalwearincreasedwiththeincreaseofcuttingspeedandfeedrate,andthetemperatureandcontactpressurewerethemainfactorsaffectingthefrictionalwear.AmodeloffrictionalwearwasdevelopedbasedontheArchard'swearlawandthefiniteelementanalysis,whichcanpredictthetool-chipfrictionalwearwithhighaccuracy.Theexperimentalandsimulationresultsrevealedthatthedevelopedmodelcanprovideimportantguidanceforselectionofcuttingparametersandoptimizationoftooldesignintheultra-precisionmachiningofaluminum-basedcompositematerials.Furtheranalysisonthedevelopedwearmodelrevealedthatthechipthicknessandcuttingforcesalsoplayedaroleinthetool-chipfrictionalwear.Thenon-uniformityofthechipthicknessledtonon-uniformstressdistributionatthetool-chipinterfaceandresultedinunevenwear.Thecuttingforcesactedasthedrivingforcefortheslidingmotionbetweenthetoolandthechip,whichincreasedtheslidingdistanceandwearrate.

Thedevelopedwearmodelcanalsobeusedtoevaluatetheeffectivenessofdifferenttoolmaterialsandcoatingsinreducingthetool-chipfrictionalwear.Forexample,diamond-likecarbon(DLC)coatingshavebeenreportedtoreducethecoefficientoffrictionandwearrateinthemachiningofaluminum-basedcompositematerials.ThroughsimulatingthewearperformanceofDLC-coatedtools,thewearmodelcanguidethetoolcoatingselectionandoptimization.

Inaddition,thewearmodelcanbeincorporatedintotheprocesssimulationsoftwaretopredictthetoollifeandoptimizethecuttingparametersintheultra-precisionmachiningofaluminum-basedcompositematerials.Byconsideringthetool-chipfrictionalwear,thesimulationresultscanprovidemoreaccuratepredictionsonthemachiningquality,cuttingefficiency,andtoolwear.

Inconclusion,theinvestigationonthetool-chipfrictionalwearpropertiesandthedevelopmentofanaccuratewearmodelarecrucialfortheultra-precisionmachiningofaluminum-basedcompositematerials.ThedevelopedwearmodelbasedontheArchard'swearlawandthefiniteelementanalysiscanpredictthetool-chipfrictionalwearwithhighaccuracyandprovideimportantguidancefortheselectionofcuttingparametersandoptimizationoftooldesign.Moreover,thewearmodelcanalsobeutilizedfortoolwearmonitoringduringthemachiningprocess.Bycomparingthepredictedwearwiththeactualwearofthetool,thetoolconditioncanbemonitoredinreal-time,andthenecessarycorrectiveactionscanbetakentopreventtoolfailureandimprovethemachiningefficiency.

Furthermore,thewearmodelcanbeextendedtoincludeotherwearmechanismssuchasadhesion,abrasion,andoxidation.Thiswouldprovideacomprehensiveunderstandingofthewearbehaviorofthetoolandimprovetheaccuracyofthewearprediction.Theintegrationofmultiplewearmechanismswouldalsofacilitatethedevelopmentofadvancedtoolmaterialsandcoatingsthatcanwithstandthecomplexwearenvironmentinultra-precisionmachining.

Inconclusion,thestudyoftool-chipfrictionalwearandthedevelopmentofawearmodelareessentialforachievinghigh-qualityandefficientultra-precisionmachiningofaluminum-basedcompositematerials.Thewearmodelhasthepotentialtoguidetooldesignoptimization,predicttoolwear,monitortoolcondition,andimprovethemachiningefficiency.Futureresearchinthisareacanfocusontheintegrationofmultiplewearmechanisms,thedevelopmentofadvancedtoolmaterialsandcoatings,andtheapplicationofwearmodelsinreal-timetoolwearmonitoringandoptimizationofcuttingparameters.Anotherareawherethewearmodelcanbeextensivelyusedisintheoptimizationofcuttingparametersforultra-precisionmachiningofaluminum-basedcomposites.Byintegratingthewearmodelwithprocesssimulationsoftware,theoptimalcuttingparameterscanbedeterminedbeforehand,therebyreducingthenumberofexperimentsrequiredtooptimizetheprocessparameters.

Moreover,thewearmodelcanalsoaidintheselectionofcuttingfluidsandlubricants,whichcansignificantlyaffectthetoolwearandthesurfacefinishofthemachinedcomponent.Thewearmodelcanbeusedtoevaluatetheperformanceofdifferentcuttingfluidsandselecttheoptimaloneforachievingthedesiredcuttingperformance.

Finally,thewearmodelcanalsobeappliedtothedesignofnoveltoolgeometriesthatcanimprovethetoollifeandcuttingperformance.Bysimulatingthewearbehaviorofdifferenttoolgeometries,theoptimalgeometrycanbedeterminedthatcanwithstandthecomplexwearenvironmentinultra-precisionmachining.

Insummary,thedevelopmentofawearmodelfortool-chipfrictionalwearinultra-precisionmachiningofaluminum-basedcompositeshasnumerousbenefitssuchas