外文翻译--多工具钻参数的优化选择.doc

英文原文原文节选自JournalofMaterialsProcessingTechnology103(2000)318-323Optimalselectionofparametersinmulti-tooldrilling原文：Optimalselectionofparametersinmulti-tooldrillinga.DepartmentofMechanicalEngineering,IndianInstituteofTechnology,Chennai600036,Indiab.DepartmentofHumanitiesandSocialSciences,IndianInstituteofTechnology,Chennai600036,IndiaAccepted4January2000AbstractInhole-makingoperation,thefinalsizemaybeobtainedbydrillingwithasingledrillorpilot-drillingofoneormoreholesfollowedbyenlargementtothefinalsize.Inthispaper,amodelbasedonproductioncostispresentedandtheoptimalconditionsareobtainedconsideringtechnologicalandmachinetoolconstraints.Thisapproachisquiteusefulinarrivingatthecuttingparametersautomaticallyinacomputer-assistedprocessplanningsystem.Keywords:Optimalselection；Multi-tooldrilling；Computer-assistedprocessplanningsystemNomenclatureDdrilldiameter,mmdpilot-drilldiameter,mmFthrustforceindrilling,Nh1toolreturnrate,min/mmh2timefortoolretract-advance,mink1operatingcostofdrillingmachine,$/minktdrillcost,$ldepthofdrilling,mmMtorqueindrilling,Nmsfeed,mm/revTdrill-life,minTRpreventivetool-lifetdepthofcut,错误!未找到引用源。（D-d）,mmtetimefortool-exchange,mintmdrillingtime,mintptoolpreparationtime,minUcostofdrilling,$Vcuttingspeed,m/min1.IntroductionOneoftheimportantstepsinanycomputer-assistedprocessplanning(CAPP)istodeterminethecuttingparametersautomatically.Oncetheoperationsequencesandtheappropriatetoolshavebeendetermined,successofthemachiningprocessdependsontheselectionofcuttingparameters.Forexample,inthecaseofturning,cuttingparametersincludedepthsofcut,feedsandcuttingspeeds.Thecuttingparametersareselectedtoachievethedesirableperformancesuchasgoodsurfacefinish,dimensionalaccuracyofthecomponent,easychipremovalandsoon.Inaddition,theymustalsosatisfyaneconomiccriterionlikeminimumproductioncostormaximumproductionrate.Thusmachiningeconomicsinvolvestheoptimalselectionofmachiningparameterssuchascuttingspeed,feedanddepthofcutsubjecttocertaintechnologicalconstraintssuchastoolwear,dimensionalaccuracy,surfacefinishandmachinetoolcapabilities.Ahumanprocessplannerselectsthepropermachiningparametersusinghis/herexperienceorfromhandbooksbasedonthepartgeometry,technologicalrequirements,themachinetool,cuttingtoolselectedandthepartmaterial.Analogously,inaCAPPsystem,toselectpropercuttingparameters,alltheinformationregardingthepartandthemachiningresourcesshouldbeavailabletothesystemincomputerinterpretableformat.Thereareseveralwaysthiscouldbeachieved.Existingcomputerizedmachiningparameterselectionsystemscanbeclassifiedintofourmajorcategories:Datastorageandretrievalsystems,empiricalequations,expertsystemsandmathematicalmodels.Ofthesefour,themathematicalapproachhasreceivedmuchattention,asiteliminatestheneedforalargeamountofdatastoragerequiredbytheretrievalprocedureandcanbeusedtoarriveatoptimalmachiningparameters.Optimizationofsingle-and-multiple-passmachiningprocess,especiallyturninghasbeeninvestigatedextensively1,2.However,thedrillingprocesshasnotreceivedthesameattentionthoughasmuchas40%ofthemachiningtimeisdevotedtohole-makingasrevealedbyasurveyofthemedium-sizedindustry3.Whenthetotalstocktoberemovedtoachievethefinalholesizeexceedsthemaximumallowabledepthofcutduetovariousconstraintsonavailablemachinepower,toolforce,etc.itisimperativethatmulti-toolmachiningisemployed.Forexample,ifaholeofbigsizeistobedrilled,thismaybeprecededbydrillingofoneortwopilotholes.Thus,thesub-divisionofdepthsofcutisanimportantconsiderationinmulti-tooldrillingalso.Inthispaper,multi-tooldrillingprocessisconsideredandtheminimumproductioncostistakenastheobjectivewiththeconstraintsofthespeedandfeedranges,strengthofthedrill,maximumaxialthrustallowedbythefeedmechanismandpowerofthemachinetool.Thismodelalsoincludesthepreventivetoolreplacementstrategypractisedinmanyindustries.Foratypicalcase,theresultsarepresentedinthispaper.2.Multi-tooldrillingmodelInmanufacturedcomponents,moreholesareproducedthananyothershapeandalargeproportionofthosearemadebydrilling.Thebasicmotionsrequiredfordrillingarerelativerotationbetweentheworkpieceandthetoolwithrelativelongitudinalfeeding.Beinganimportantproductionprocess,thegeometryofthedrill,thecuttingmechanicsandthelifeaspectshavebeenextensivelystudied4-8.However,theoptimalconditionsindrilling,particularlyinmulti-toolmachining,havenotbeenstudied.Indrilling,multi-toolmachiningisused,whenthetotalstocktoachievethefinalsizeexceedsthemaximumallowabledepthofcut(i.e.thedrillsize)duetovarioustechnologicalconstraintsandthemachinecapabilities.Inmulti-toolmachining,drillsofdifferentsizesareusedtoarriveatthefinaldimension.Whentherequiredsizecanbemachinedwithonedrillitself(i.e.withoutapilot-holedrilling),itisreferredtoassinglestagedrilling.Iftheholesizetobedrilledislarge,oneormorepilotholeshavetobedrilledbeforeenlargingtheholewithafinalsizedrill(Fig.1).Thefirstholeisdrilledinsolidworkmaterialandhenceitisreferredtoasdirectdrilling.Theselectionofpilot-drills,whichdecidesthesub-divisionofdepthsofcut,canbedoneonthebasisoftotalproductioncostmodel.Totalproductioncostmodelforthemulti-tooldrillingwiththeconstraintsofthespeedandfeedranges,strengthofthedrill,maximumaxialthrustallowedbythefeedmechanismandpowerofthemachinetoolisgivenbelow.Themodelmakesuseoftoollifeequationandpreventivetoolreplacementstrategypractisedindustrially.Toollifeequationindrillingisexpressedintermsofcuttingspeed(V),feed(s)anddrillsize(D)aswhereCv,xv,yv,zvandmaretool-lifeconstantandexponents,whosevaluesdependonthetoolandworkmaterialcombination.Kvisageneralcorrectionfactorforothermachiningconditions9.tintheaboveexpressionreferstodepthofcutinenlargingaholeanditsvalueisgivenbywheredisthepilot-holesize.Totalcost(Ut):ThetotalcostofdrillingaholeisgivenbywhereUdisthecostofdirectdrilling,Ueithecostofenlargingtheithholeandnreferstothenumberofenlargingoperations.Inasingle-stagedrilling,thesecondtermisabsent.A4representsthecostoftoolpreparationgivenbywheretpisthetoolpreparationtimeandk1theoverheadcost.Costofdirectdrilling/enlargingisgivenbyThefirsttermrepresentsthemachiningcostwherethetimerequiredfordrillingisgivenbywherelisthelengthofdrilling,sthedrillfeedandNtherpmofthedrill.Thesecondtermdenotesthetoolcostandthethirdtermrepresentsthetool-exchangecost.Thefourthtermgivesthecostcorrespondingtoidletoolmotions,whereh1referstotherateatwhichthetoolreturnisdoneafterthecompletionofdrillingandh2denotesthetimetakenforretractingandadvancingthedrilltostartthedrillingcycle.Theminimizationofcostfunction(Eq.(5)isdoneforeachstageconsideringthefollowingaspects.Toollife(T):Thetool-lifeindrillingisgivenbyEq.(1).Forthepreventivetoolreplacementstrategy,thetoollifeisspecifiedonthebasisofshopfloorpractice.Thechosenparametershavetosatisfythisrequirement.Usingtheminimumandmaximumsp