外文翻譯--高速研磨技術(shù)的應(yīng)用與展望.doc

C1外文翻譯：英文+中文16頁(yè)5909字?jǐn)?shù)High-speedgrinding-applicationsandfuturetechnologyM.J.Jackson,*,C.J.Davis,M.P.Hitchhiker,B.MillsAbstractThebasicmechanismsandtheapplicationsforthetechnologyofhigh-speedgrindingwithCBNgrindingwheelsarepresented.Inadditiontodevelopmentsinprocesstechnologyassociatedwithhigh-speedmachining,thegrindingmachine,coolantsystem,andthegrindingtoolalsoneedtoadapttohigh-speedmachining.Workpiece-relatedfactorsinurningtheresultsofmachiningarealsodiscussed.Thepaperconcludeswithapresentationofcurrentresearchandfuturedevelopmentsintheareaofhigh-speedgrinding,andthedevelopmentofhigh-speedCBNcamshaftgrinding.Allrightsreserved.1.IntroductionMorethan25yearsofhigh-speedgrindinghaveexpandedthefieldofapplicationforgrindingfromclassicalfinishmachiningtohigh-performancemachining.High-speedgrindingoffersexcellentpotentialforgoodcomponentqualitycombinedwithhighproductivity.Onefactorbehindtheinnovativeprocesshasbeentheneedtoincreaseproductivityforconventionalfinishingprocesses.Inthecourseofprocessdevelopmentithasbecomeevidentthathigh-speedgrindingincombinationwithpreliminarymachiningprocessesclosetothefinishedcontourenablestheconfigurationofnewprocesssequenceswithhigh-performancecapabilities.Usingtheappropriategrindingmachinesandgrindingtools,itispossibletoexpandthescopeofgrindingtohigh-performancemachiningofsoftmaterials.Initially,abasicexaminationofprocessmechanismsisdiscussedthatrelatestheconfigurationofgrindingtoolsandtherequirementsofgrindingsoftmaterials.Theeffectofaneffectiveandenvironmentallyfriendlycoolantsystemisalsoinvestigatedinadditiontotheeffectofworkpiece-relatedvariablesonthesuitabilityofusinghigh-speedgrindingtechniques.2.Theoreticalbasisofhigh-speedgrindingInviewoftherandomdistributionofcuttingedgesandcutting-edgeshapes,statisticalmethodsareappliedtoanalysesthecuttingmechanismingrinding.Themeanunreformedchipthickness,hcu,andthemeanchiplength,lcu,areemployedasvariablestodescribetheshapeofthechip.Theunreformedchipthicknessisdependentonthestaticdensityofcuttingedges,Cstat,andonthegeometricandkinematicsvariables1,2:C2(1)whereVwistheworkpiecespeed,VSthegrindingwheelspeed,aethedepthofcut,deqtheequivalentgrindingwheeldiameter,and，aregreaterthanzero.Onthebasisofthisrelationship,itcanbeestablishedthatanincreaseinthecuttingspeed,assumingallotherconditionsareconstant,willresultinareductionintheunreformedchipthickness.Theworkpiecematerialismachinedwithalargernumberofabrasivegraincontacts.Atthesametime,thenumberofcuttingedgesinvolvedintheprocessdecreases.Thisleadstotheadvantagespromisedbyhigh-speedgrindingwhichischaracterizedbyareductioningrindingforces,grindingwheelwear,andinworkpiecesurfaceroughness.Consequently,increasingthespeedofthegrindingwheelcanleadtoanincreaseinthequalityoftheworkpiecematerial,oralternatively,anincreaseinproductivity.Theprocesstechnologydependsonthecharacteristicsandqualityrequirementsoftheworkpiecetobemachined.Asthecuttingspeedincreases,thequantityofthermalenergythatisintroducedintotheworkpiecealsoincreases.Anincreaseincuttingspeedisnotnormallyaccompaniedbyaproportionalreductioninthetangentialgrindingforce,andthusresultsinanincreaseinprocesspower.Reducingthelengthoftimetheabrasivegrainisincontactwiththeworkpiececanreducethequantityofheatintotheworkpiece.Anincreaseinthemachiningrateoftheprocessisnecessaryforthistohappen,wherethechipthicknessisincreasedtothelevelthatappliestolowercuttingspeedswithoutC3overloadingthegrindingwheel.Experimentalresults3illustratethatincreasingthecuttingspeedbyafactoroftwowhilemaintainingthesamemetalremovalrateleadstoareductioninthetangentialforcebut,unfortunately,leadstoanincreaseintheamountofworkdone.Owingtoconstantgrindingtime,thereisanincreaseintheprocessenergyperworkpieceand,subsequently,inthetotalthermalenergygenerated.Whenthematerialremovalrateisalsoincreasedtherisingtangentialforceresultsinafurtherincreaseingrindingpower.Thequantityofthermalenergyintroducedintotheworkpieceislowerthantheinitialsituationwhenthesame-machinedworkpiecevolumeappliesdespitethehighercuttingspeedandincreasedmetalremovalrate.Theseconsiderationsshowthatmachiningproductivitycanbeincreasedusinghigh-speedgrindingwithouthavingtoacceptundesirablethermaleffectsongroundcomponents.Therearethreefieldsoftechnologythathavebecomeestablishedforhigh-speedgrinding.Theseare1.High-speedgrindingwithCBNgrindingwheels.2.High-speedgrindingwithaluminumoxidegrindingwheels.3.Grindingwithaluminumoxidegrindingwheelsinconjunctionwithcontinuousdressingtechniques(CDgrinding).Materialremovalratesresultinginasuperproportionalincreaseinproductivityforcomponentmachininghavebeenachievedforeachofthesefieldsoftechnologyinindustrialapplications4,5(Fig.1).Highequivalentchipthicknessofbetween0.5and10mmareacharacteristicfeatureofhigh-speedgrinding.CBNhigh-speedgrindingisemployedforalargeproportionoftheseapplications.AnessentialcharacteristicofthistechnologyisthattheperformanceofCBNisutilizedwhenhighcuttingspeedsareemployed.3.Grindingtoolsforhigh-speedgrindingCBNgrindingtoolsforhigh-speedmachiningaresubjecttospecialrequirementsregardingresistancetofractureandwear.Gooddampingcharacteristics,highrigidity,andgoodthermalconductivityarealsodesirable.Suchtoolsnormallyconsistofabodyofhighmechanicalstrengthandacomparablythincoatingofabrasiveattachedtothebodyusingahigh-strengthadhesive.Thesuitabilityofcubicboronnitrideasanabrasivematerialforhigh-speedmachiningofferrousmaterialsisattributedtoitsextremehardnessanditsthermalandchemicaldurability.Highcuttingspeedsareattainableaboveallwithmetalbondingsystems(Fig.2).Onemethodthatusessuchbondingsystemsiselectroplating,wheregrindingwheelsareproducedwithasingle-layercoatingofabrasiveCBNgrainmaterial.Theelectro-depositednickelbonddisplaysoutstandinggrainretentionproperties.Thisprovidesahigh-levelgrainprojectionandlargechipspaces.Cuttingspeedsof280ms-1arepossible6.Theservicelifeendswhentheabrasivelayerwearsout.C4ThehighroughnessofthecuttingsurfacesofelectroplatedCBNgrindingwheelshasdisadvantageouseffects.Thehighroughnessisaccountabletoexposedgraintipsthatresultfromdifferentgrainshapesandgraindiameters.AlthoughelectroplatedCBNgrindingwheelsarenotconsideredtobedressableintheconventionalsense,theresultantworkpiecesurfaceroughnesscanneverthelessbeinfluencedwithinnarrowlimitsbymeansofaso-calledtouch-dressingprocess.Thisinvolvesremovingtheperipheralgraintipsfromtheabrasivecoatingbymeansofverysmalldressinginfeedstepsintherangeofdressingdepthsofcutbetween2and4mm,therebyreducingtheeffectiveroughnessofthegrindingwheel7.Multi-layerbondingsystemsforCBNgrindingwheelsincludesinteredmetalbonds,resinbonds,andvitrifiedbonds.Multi-layermetalbondspossesshighbondhardnessandwearresistance.Profilingandsharpeningthesetoolsisacomplexprocess,however,onaccountoftheirhighmechanicalstrength.Syntheticresinbondspermitabroadscopeofadaptationforbondingcharacteristics.However,thesetoolsalsorequireasharpeningprocessafterdressing.Thepotentialforpracticalapplicationofvitrifiedbondshasyettobefullyexploited.Inconjunctionwithsuitablydesignedbodies,newbonddevelop