外文翻译--计算机控制程序员与操作员该做什么.doc -- 5 元

英文原文WhatcomputercontrolprogrammersandoperatorsdoComputercontrolprogrammersandoperatorsusecomputerizednumericalcontrolCNCmachinestocutandshapeprecisionproducts,suchasautomobileparts,machineparts,andcompressors.CNCmachinesincludemachiningtoolssuchaslathes,multiaxisspindles,millingmachines,andelectricaldischargemachinesEDM,butthefunctionsformerlyperformedbyhumanoperatorsareperformedbyacomputercontrolmodule.CNCmachinescutawaymaterialfromasolidblockofmetal,plastic,orglassknownasaworkpiecetoformafinishedpart.Computercontrolprogrammersandoperatorsnormallyproducelargequantitiesofonepart,althoughtheymayproducesmallbatchesoroneofakinditems.TheyusetheirknowledgeoftheworkingpropertiesofmetalsandtheirskillwithCNCprogrammingtodesignandcarryouttheoperationsneededtomakemachinedproductsthatmeetprecisespecifications.BeforeCNCprogrammersalsoreferredtoasnumericaltoolandprocesscontrolprogrammersmachineapart,theymustcarefullyplanandpreparetheoperation.First,theseworkersreviewthreedimensionalcomputeraided/automateddesignCADblueprintsofthepart.Next,theycalculatewheretocutorboreintotheworkpiece,howfasttofeedthemetalintothemachine,andhowmuchmetaltoremove.Theythenselecttoolsandmaterialsforthejobandplanthesequenceofcuttingandfinishingoperations.Next,CNCprogrammersturntheplannedmachiningoperationsintoasetofinstructions,Theseinstructionsaretranslatedintoacomputeraided/automatedmanufacturingCAMprogramcontainingasetofcommandsforthemachinetofollow.Thesecommandsnormallyareaseriesofnumbershence,numericalcontrolthatdescribeswherecutsshouldoccur,whattypeofcutshouldbeused,andthespeedofthecut.CNCprogrammersandoperatorschecknewprogramstoensurethatthemachinerywillfunctionproperlyandthattheoutputwillmeetspecifications.Becauseaproblemwiththeprogramcoulddamagecostlymachineryandcuttingtools,computersimulationsmaybeusedtochecktheprograminsteadofatrialrun.Iferrorsfound,theprogrammustbechangedandresteduntiltheproblemisresolved.Inaddition,growingconnectivitybetweenCAD/CAMsoftwareandCNCmachinetoolsisraisingproductivitybyautomaticallytranslatingdesignsintoinstructionsforthecomputercontrolleronthemachinetool.ThesenewCAMtechnologiesenableprogramstobeeasilymodifiedforuseonotherjobswithsimilarspecifications.Aftertheprogrammingworkiscompleted,CNCoperatorsalsoreferredtoascomputercontrolledmachinetooloperatorsperformthenecessarymachiningoperations.TheCNCoperatorstransferthecommandsfromtheservertotheCNCcontrolmoduleusingacomputernetworklinkorfloppydisk.Manyadvancedcontrolmodulesareconversational,meaningthattheyasktheoperatoraseriesofquestionsaboutthenatureofthetask..CNCoperatorspositionthemetalstockontheCNCmachinetoollathe,millingmachine,orothersetthecontrols,andletthecomputermakethecuts.Heavierobjectsmaybeloadedwiththeassistanceofotherworkers,autoloaders,acrane,oraforklift.Duringthemachiningprocess,computercontroloperatorsconstantlymonitorthereadoutsfromtheCNCcontrolmodule,checkingtoseeifanyproblemsexist.Machinetoolshaveuniquecharacteristics,whichcanbeproblematic.Duringamachiningoperation,theoperatormodifiesthecuttingprogramtoaccountforanyproblemsencountered.Unique,modifiedCNCprogramsaresavedforeverydifferentmachinethatperformsatask.CNCoperatorsdetectsomeproblemsbylisteningforspecificsoundsforexample,dullcuttingtoolorexcessivevibration.Dullcuttingtoolsareremovedandreplacedandreplaced.Machinetoolsrotateathighspeeds,whichcancreateproblemswithharmonicvibrationsintheworkpiece.vibrationscausethemachinetoolstomakeminorcuttingerrors,hurtingthequalityoftheproduct.Operatorslistenforvibrationsandthenadjustthecuttingspeedtocompensate.inolder,slowermachinetools,thecuttingspeedwouldbereducedtoeliminatethevibrations,buttheamountoftimeneededtofinishtheproductwouldincreaseataresult.innewer,highspeedCNCmachines,increasingthecuttingspeednormallyeliminatesthevibrationsandreducesproductiontime.CNCoperatorsalsoensurethattheworkpieceisbeingproperlylubricatedandcooled,becausethemachiningofmetalproductsgeneratesasignificantamountofheat.Computercontrolprogrammersandoperatorstraininvariouswaysinapprenticeshipprograms,informallyonthejop,andinsecondary,vocational,orpostsecondaryschools.Duetoashortageofqualifiedapplicants,manyemployersteachintroductorycourses,whichprovideabasiccomputersandelectronicsalsoishelpful.Experiencewithmachinetoolsisextremelyimportant.Infact,manyentrantstotheseoccupationshavepreviouslyworkedasmachinistsormachinesetters,operators,andtenders.Personsinterestedinbecomingcomputercontrolprogrammersoroperatorsshouldbemechanicallyinclinedandabletoworkindependentlyanddohighlyaccuratework.Highschoolorvocationalschoolcoursesinmathematicstrigonometryandalgebra,blueprintreading,computerprogramming,metalworking,anddraftingarerecommended.Apprenticeshipprogramsconsistofshoptrainingandrelatedclassroominstruction.Inshoptraining,apprenticeslearnfiling,handtapping,anddowelfitting,aswellastheoperationofvariousmachinetools.Classroominstructionincludesmath,physics,programming,blueprintreading,CADsoftware,safely,andshoppractices.Skilledcomputercontrolprogrammersandoperatorsneedanunderstandingofthemachiningprocess,includingthecomplexphysicsthatoccuratthecuttingpoint.Thus,mosttrainingprogramsteachCNCoperatorsandprogrammerstoperformoperationsonmanualmachinespriortooperatingCNCmachine.Agrowingnumberofcomputercontrolprogrammersandoperatorsreceivemostoftheirformaltrainingfromcommunityortechnicalcolleges.LessskilledCNCoperatorsmayneedonlyacoupleofweeksofonthejobtraining.Computercontrolprogrammersandoperatorscanadvanceinseveralways.ExperiencedCNCoperatorsmaybecomeCNCprogrammers,andsomearepromotedtosupervisoryoradministrativepositionintheirfirms.Afewopentheirownshops.Computercontrolprogrammersandoperatorsshouldhaveexcellentjobopportunities.Duetothelimitednumberofpeopleenteringtrainingprograms,employersareexpectedtohavecontinuetohavedifficultyfindingworkerswiththenecessaryskillsandknowledge.JobgrowthinbothoccupationswillbedrivenbytheincreasinguseofCNCmachinetools.AdvancesinCNCmachinetoolsandmanufacturingtechnologywillfurtherautomateproduction,boostingCNCoperatorsproductivityandlimitingemploymentgrowth.ThedemandforcomputercontrolprogrammerswillbenegativelyaffectedbytheincreasinguseofsoftwarethatautomaticallytranslatespartandproductdesignsintoCNCmachinetoolinstructions.WhatisCNCCNCstandsforComputerizedNumericalControlandhasbeenaroundsincetheearly1970s.Priortothis,itwascalledNC,fornumericalcontrol.Whilepeopleinmostwalksoflifehaveneverheardofthisterm,CNChastouchedalmosteveryformofmanufacturingprocessinonewayoranother.Ifyoullbeworkingmanufacturing,itslikelythatyoullbedealingwithCNConaregularbasis.BeforeCNCWhilethereareexceptionstothisstatement,CNCmachinesreplaceorworkinconjunctionwithsomeexistingmanufacturingprocess.Takeoneofthesimplestmanufacturingprocesses,drillingholes,forexample.Adrillpresscanofcoursebeusedtomachineholes.Apersoncanplaceadrillchuckthatissecuredinthespindleofthedrillpress.Theycanthenmanuallyselectthedesiredspeedforrotationcommonlybyswitchingbeltpulleys,andactivatethespindle.Thentheymanuallypullonthequilllevertodrivethedrillintotheworkpiecebeingmachined.Asyoucaneasilysee,thereisalotofmanualinterventionrequiredtouseadrillpresstodrillholes.ApersonisrequiredtodosomethingalmosteverystepalongthewayWhilethismanualinterventionmaybeacceptableformanufacturingcompaniesifbutasmallnumberofholesorworkpiecesmustbemachined,asquantitiesgrow,sodoesthelikelihoodforfatigueduetothetediousnessoftheoperation.Anddonotethatweveusedoneofthesimplestmachiningoperationsdrillingforourexample.Therearemorecomplicatedmachiningoperationsthatwouldrequireamuchhigherskilllevelandincreasethepotentialformistakesresultinginscrapworkpiecesofthepersonrunningtheconventionalmachinetool.WecommonlyrefertothestyleofmachinethatCNCisreplacingastheconventionalmachine.Bycomparison,theCNCequivalentforadrillpresspossiblyaCNCmachiningcenterorCNCdrillingtappingcentercanbeprogrammedtoperformthisoperationinamuchmoreautomaticfashion.EverythingthatthedrillpressoperatorwasdoingmanuallywillnowbedonebytheCNCmachine,includingplacingthedrillinthespindle,activatingthespindle,positioningtheworkpieceunderthedrill,machiningthehole,andturningoffthespindle.HowCNCworksAsyoumightalreadyhaveguessed,everythingthatanoperatorwouldberequiredtodowithconventionalmachinetoolsisprogrammablewithCNCmachines.Oncethemachineissetupandrunning,aCNCmachineisquitesimpletokeeprunning.InfactCNCoperatorstendtogetquiteboredduringlengthyproductionrunsbecausethereissolittletodo.WithsomeCNCmachines,eventheworkpieceloadingprocesshasbeenautomated.Letslookatsomeofthespecificprogrammablefunctions.MotioncontrolAllCNCmachinetypessharethiscommonalityTheyallhavetwoormoreprogrammabledirectionsofmotioncalledaxis.Anaxisofmotioncanbelinearalongastraightlineorrotaryalongacircularpath.OneofthefirstspecificationsthatimplyaCNCmachinescomplexityishowmanyaxesithas.Generallyspeaking,themoreaxes,themorecomplexthemachine.TheaxesofanyCNCmachinearerequiredforthepurposeofcausingthemotionaneededforthemanufacturingprocess.Inthedrillingexample,these3axeswouldpositionthetoolovertheholetobemachinedintwoaxesandmachinetheholewiththethirdaxis.Axesarenamedwithletters.CommonlinearaxisnamesareX,Y,andZ.CommonrotaryaxisnamesareA,B,andC.Thesearerelatedtothecoordinatesystem.ProgrammableaccessoriesACNCmachinewouldntbeveryhelpfulifallitcouldonlymovetheworkpieceintwoormoreaxes.AlmostallCNCmachinesareprogrammableinseveralotherways.ThespecificCNCmachinetypehasalottodowithitsappropriateprogrammableaccessories.Again,anyrequiredfunctionwillbeprogrammableonfullblownCNCmachinetools.Herearesomeexamplesforonemachinetypemachiningcenters.AutomatictoolchangerMostmachiningcenterscanholdmanytoolsinatoolmagazine.Whenrequired,therequiredtoolcanbeautomaticallyplacedinthespindleformachining.SpindlespeedandactivationThespindlespeedinrevolutionsperminutecanbeeasilyspecifiedcanbeturnedoninaforwardorreversedirection.Itcanalso,ofcourse,beturnedoff.CoolantManymachiningoperationsrequirecoolantforlubricationandcoolingpurposes.Coolantcanbeturnedinandofffromwithinthemachinecycle.TheCNCprogramThinkofgivinganyseriesofstepbystepinstructions.ACNCprogramisnothingmorethananotherkindofinstructionset.Itswritteninsentencelikeformatandthecontrolwillexecuteitinsequentialorder,stepbystep.AspecialseriesofCNCwordsareusedtocommunicatewhatthemachineisintendedtodo.CNCwordsbeginwithletteraddresseslikeFforfederate,Sforspindlespeed,andX,YZforaxismotion.Whenplacedtogetherinalogicalmethod,agroupofCNCwordsmakeupacommandthatresembleasentence.TheCNCcontrolTheCNCcontrolwillinterpretaCNCprogramandactivatetheseriesofcommandsinsequentialorder.Asitreadstheprogram,theCNCcontrolwillactivatetheappropriatemachinefunctions,causeaxismotion,andingeneral,followtheinstructionsgivenintheprogram.AlongwithinterpretingtheCNCprogram,theCNCcontrolhasseveralotherpurposes.AllcurrentmodelCNCcontrolsallowprogramstobemodifiededitedifmistakesarefound.TheCNCcontrolallowsspecialverificationfunctionslikedryruntoconfirmthecorrectnessoftheCNCprogram,TheCNCcontrolallowscertainimportantoperatorinputstobespecifiedseparatefromtheprogram,liketoollengthvalues.Ingeneral,theCNCcontrolallowsallfunctionsofthemachinetobemanipulated.WhatisaCAMsystemForsimpleapplicationslikedrillingholes,theCNCprogramcanbedevelopedmanually.Thatis,aprogrammerwillsitdowntowritetheprogramarmedonlywithpencil,paper,andcalculator.Again,forsimpleapplications,thismaybetheverybestwaytodevelopCNCprograms.