外文翻譯--計算機輔助設計及制造CADCAM.doc

本科畢業(yè)論文（設計）相關中英文翻譯資料資料題目：計算機輔助設計與制造學生姓名：所在院系：機電學院所學專業(yè)：機電技術(shù)教育CADandCAMTheenginelathe,oneoftheoldestmetalremovalmachines,hasanumberofusefulandhighlydesirableattributes.Todaytheselathesareusedprimarilyinsmallshopswheresmallerquantitiesratherthanlargeproductionrunsareencountered.Inthebeginning,CADsystemswerenomorethanagraphicseditorwithsomebuilt-indesignsymbols.Thegeometryavailabletotheuserwaslimitedtolines,circulararcs,andthecombinationofthem.Thedevelopmentoffree-formcurvesandsurfaces,suchasCoonspatch,Bezierspatch,andB-spline,enablesaCADsystemsallowadesignertomoveintothethirddimension.Becauseathree-dimensionalmodelcontainsenoughinformationforNCcutter-pathprogramming,thelinkagebetweenCADandNCcanbedeveloped.SocalledturnkeyCAD/CAMsystemsweredevelopedbasedonthisconceptandbecamepopularinthe1970sand1980s.The1970smarkedthebeginningofanewerainCADtheinventionofthree-dimensionalsolidmodeling.Inthepast,three-dimensional,wire-framemodelsrepresentedanobjectonlybyitsboundingedges.Theyareambiguousinthesensethatseveralinterpretationsmightbepossibleforasinglemodel.Thereisalsonowaytofindthevolumetricinformationofamodel.Solidmodelscontaincompleteinformation；therefore,notonlycantheybeusedtoproduceengineeringdrawing,butengineeringanalysiscanbeperformedonthesamemodelaswell.Later,manycommercialsystemsandresearchsystemsweredeveloped.QuiteafewofthesesystemswerebasedonthePADLandBUILDsystems.Althoughtheyarepowerfulinrepresentation,manydeficienciesstillexist.Forexample,suchsystemshaveextremecomputationandresource(memory)requirements,anunconventionalwayofmodelingobjectsandalackoftolerancecapabilityhaveallhinderedCADapplications.Itwasnotuntilthemid-1980sthatsolidmodelersmadetheirwayintothedesignenvironment.Today,theiruseisascommonasdraftingandwire-framemodelapplication.CADimplementationsonpersonalcomputers(PCs)havebroughtCADtothemasses.ThisdevelopmenthasmadeCADavailableandaffordable.CADoriginallywasatoolusedonlybyaerospaceandothermajorindustrialcorporation.TheintroductionofPCCADpackages,suchasAutoCAD,VersaCAD,CADKEYsystems,madesmallcompanies,evenindividuals,ownanduseCAD.By1988,morethan100,000PCCADPackageshadbeensold.Today,PC-basedsolidmodelersareavailableandarebecomingincreasinglypopular.BecauserapiddevelopmentsinmicrocomputershaveenabledPCstocarrytheheavycomputationalloadnecessaryforsolidmodeling,manysolidgraphicsuserinterface(GUI),CADsystemscanbeportedeasilyfromonecomputertoanother,mostmajorCADsystemsareabletorunonavarietyofplatforms.Thereislittledifferencebetweenmainframe,workstation,andPC-basedCADsystems.Whenadesignhasfrozen,manufacturingcanbegin.Computershaveanimportantroletoplayinmanyaspectsofproduction.Numericallycontrolled(NC)machinetoolsneedapartprogramtodefinethecomponentsbeingmade；computertechniquesexisttoassist,andinsomecasesvirtuallyautomatethegenerationofpartprograms.Modernshipbuildingfabricatesstructuresfromweldedsteelplatesthatarecutfromalargesteelsheet.Computer-controlledflamecuttersareoftenusedforthistaskandthecomputerisusedtocalculatetheoptimumlayoutofthecomponentstominimizewastemetal.Printedcircuitboardassemblycanalsobeimprovedbycomputermethods.Qualityismaintainedbycomputer-controlledautomatictestequipmentthatdiagnosesfaultsinaparticularboardandrejectsdefectiveboardsfromtheassemblyline.ComputersareusedextensivelytoplottheartworkusedtoetchprintedcircuitboardsandalsotoproducepartprogramsforNCdrillingmachines.Oneofthemostimportantmanufacturingfunctionsisstockandproductioncontrol.Iftheoriginaldesignisdoneonacomputer,obtaininglistsofmaterialrequirementsisstraightforward.Standardcomputerdataprocessingmethodsareemployedtoorganizetheworkflowandordercomponentswhenrequired.Partgeometryrequirescalculationofalargenumberoftoolpositions.PartprogrammingsoftwareisusuallyincorporatedintoafamilyofCAM(ComputerAidedManufacturing)software.SomeCAMsoftwareisassociatedwithCAD(ComputerAidedDesign)softwareintoCAD/CAMstations.ThentheCAMsoftwarecanusetheCADfilesasasourceofdata,whichspeedsuptheprogrammingprocess.Partprogrammingsoftwareisuser-friendly,meaningthattheprogrammerdoesnothavetoknowthecomputerprogramminglanguageoritsoperatingsystem.Itusesscreenmenustoleadtheuserthroughtheprogrammingprocess.Datacanbeenteredviathekeyboard,themouse,orthefunctionkeys.Experiencedprogrammerscanusebuilt-inmacrocapabilitiesandadvancedtechniquessuchasafamilyofpartstobecomeevenmoreproductive.Programmingsoftwarehasadynamicgraphicsdatabasetoholdtheactualmachiningsequences.Thesesequencescanbeviewed,edited,chained,ordeleted.TheprogrammingcanbeaccomplishedwhethersinglecutsorCNCmachinecannedcyclewillbeused.Thesoftwarewillalsoautomaticallycalculatetheproperfeedsandspeedstobeusedduringthemachining,createatoolinglist,anddefinethetoolpath.Programmerscanusedifferentlayerstoassociatewitheachprofilebeingcreatedortoconstructclampsandfixturestogetacompletepictureofthepartsetup.Thetoolmotioncanbeseenasitwilloccuratthemachine.Usingpartprogrammingsoftware,theprogrammercaneasilysolvetrigonometryproblemstodefineanaccuratetoolpath.Whentheprogramisdone,theprogrammercansenditfromthePCtothemachineviaacommunicationchannelusingbuilt-insoftwarewithc