机械类英文翻译(CNC计划编程)

1FromPeterSmid,CNCProgrammingHandbook:AComprehensiveGuidetoPracticalCNCProgramming,SecondEdition,IndustrialPress,Inc.200MadisonAvenue,NewYork,2003.CHAPTER6:PROGRAMMINGPLANNINGThedevelopmentofanyCNCprogrambeginswithaverycarefullyplannedprocess.Suchaprocessstartswiththeengineeringdrawingoftherequiredpart.Beforethepartismachined,severalstepshavetoconsideredandcarefullyevaluated.Themoreeffortisputintotheplanningstageoftheprogram,thebetterresultsmaybeexpectedattheend.STEPSINPROGRAMPLANNINGThestepsrequiredinprogramplanningaredecidedbythenatureofthework.Thereisnoformulaforallthejobs,butsomebasicstepsshouldbeconsidered:*Initialinformation/Machinetoolsfeatures*Partcomplexity*Manualprogramming/computerizedprogramming*Typicalprogrammingprocedure*Partdrawing/Engineeringdata*Methodssheet/Materialsspecifications*Machiningsequence*Toolingselection*Partsetup*Technologicaldecisions*Worksketchandcalculations*QualityconsiderationsinCNCprogrammingThestepsinthelistaresuggestionsonlyaguideline.Theyarequiteflexibleandshouldalwaysbeadaptedforeachjobandtothespecificconditionsofthework.INITIALINFORMATIONMostdrawingsdefineonlytheshapeandsizeofthecompletedpartandnormallydonotspecifydataabouttheinitialblankmaterial.Forprogramming,agoodknowledgeofthematerialisanessentialstart-mainlyintermsofitssize,type,shape,condition,hardness,etc.Thedrawingandmaterialdataaretheprimaryinformationaboutthepart.Atthispoint,CNCprogramcanbeplanned.Theobjectiveofsuchaplanistousetheinitialinformationandestablishthemostefficientmethodofmachining,withallrelatedconsideration–mainlypartaccuracy,productivity,safetyandconvenience.Theinitialpartinformationisnotlimitedtothedrawingandthematerialdata,italsoincludesconditionsnotcoveredinthedrawing,suchaspro-andpost-machining,grindingallowances,assemblyfeatures,requirementsforhardening,nextmachinesetup,andothers.CollectingallthisinformationprovidesenoughmaterialtostartplanningtheCNCprogram.MACHINETOOLSFEATURESNoamountofinitialinformationisusefuliftheCNCmachineisnotsuitableforthejob.Duringprogramplanning,programmerconcentratesonaparticularmachinetool,usingaparticularCNCsystem.Eachparthastobesetupinafixture,theCNCmachinehastobelargeenoughtohandlethesizeofthepart,thepartshouldnotbeheavierthanthemaximumweightallowed.Thecontrolsystemmustbecapabletoprovidetheneededtoolpath,andsoon.Inthemostcases,theCNCequipmentisalreadyavailableintheshop.Veryfewcompaniesgoandbuya2newCNCmachinejusttosuitaparticularjob.Suchcasesareratherrareandhappenoniftheymakeeconomicsense.*MachineTypeandSizeThemostimportantconsiderationsinprogramplanningarethetypeandthesizeoftheCNCmachine,particularlyitsworkspaceorworkarea.Otherfeatures,equallyimportant,arethemachinepowerrating,spindlespeedandfeedraterange,numberoftoolstations,toolchangingsystem,availableaccessories,etc.Typically,smallCNCmachineshavehigherspindlespeedsandlowerpowerrating,largemachineshavelowerspindlespeedsavailable,buttheirpowerratingishigher.*ControlSystemThecontrolsystemistheheartofaCNCmachine.Beingfamiliarwithallthestandardandoptionalfeaturesavailableonthecontrolisamust.Thisknowledgeallowstheuseofavarietyofadvancedprogrammingmethods,suchasthemachiningcycles,subprograms,macrosandothertimesavingfeaturesofamodernCNCsystem.AprogrammerdoesnothavetophysicallyrunaCNCmachine.Yet,theprogramswillbecomebetterandmorecreativewithgoodunderstandingofthemachineanditscontrolsystem.Programdevelopmentreflectsprogrammer’sknowledgeoftheCNCmachineoperation.Oneofthemainconcernsinprogramplanningshouldbetheoperator’sperceptionoftheprogram.Toalargedegree,suchaperceptionisquitesubjective,inthesensethatdifferentoperatorswillexpresstheirpersonalpreferences.Ontheotherhand,everyoperatorappreciatesanerr-free,concise,well-documentedandprofessionallypreparedpartprogram,consistentlyandoneafteranother.Apoorlydesignedprogramisdislikedbyanyoperator,regardlessofpersonalpreferences.PARTCOMPLEXITYAtthetimethedrawing,materialandtheavailableCNCequipmentareevaluated,thecomplexityoftheprogrammingtaskbecomesmuchclearer.Howdifficultistoprogramthepartmanually?Whatarethecapabilitiesofthemachines?Whatarethecosts?Manyquestionshavetobeansweredbeforestartingtheprogram.SimpleprogrammingjobsmaybeassignedtoalessexperiencedprogrammeroftheCNCoperator.Itmakessensefromthemanagementperspectiveanditisalsoagoodwaytogainexperience.Difficultorcomplexjobswillbenefitfromacomputerizedprogrammingsystem.TechnologiessuchasComputerAidedDesign(CAD)andComputerAidedManufacturing(CAM)havebeenastrongpartofthemanufacturingprocessformanyyears.ThecostofaCAD/CAMsystemisonlyafractionofwhatitusedtobeonlyafewyearsago.Evensmallshopsnowfindthatthebenefitsofferedbymoderntechnologyaretoosignificanttobeignored.Severalprogrammingsystemsareavailablevariouscomputersandcanhandleanyjob.Foratypicalmachineshop,aWindowsbasedprogrammingsoftwarecanbeverybeneficial.AtypicalexampleofthiskindofapplicationistheverypopularandpowerfulMasterCAM,formCNCSoftware,Inc.Tolland.CT.Thereareseveralothers.MANUALPROGRAMMINGManualprogramming(withoutacomputer)hasthemostcommonmethodofpreparingapartprogramf