外文翻译--现代设计与制造.doc

ModernDesignandManufacturing1.TheComputerandManufacturingThecomputerisbringingmanufacturingintotheInformationAge.Thisnewtool,longafamiliaroneinbusinessandmanagementoperations,ismovingintothefactory,anditsadventischangingmanufacturingascertainlyasthesteamenginechangedit100yearsago.Thebasicmetalworkingprocessesarenotlikelytochangefundamentally,buttheirorganizationandcontroldefinitelywillInonerespect,manufacturingcouldbesaidtobecomingfullcircle.Thefistmanufacturingwasacottageindustry:thedesignerwasalsothemanufacturer,conceivingandfabricatingproductsoneatatime.Eventually,theconceptoftheinterchangeabilityofpartswasdeveloped,productionwasseparatedintospecializedfunctions,andidenticalpartswereproducedthousandsatatime.Today,althoughthedesignerandmanufacturermaynotbecomeoneagain,thefunctionsarebeingdrawncloseinthemovementtowardanintegratedmanufacturingsystem.Itisperhapsironicthat,atatimewhenthemarketdemandsahighdegreeofproductdiversification,thenecessityforincreasingproductivityandreducingcoatsisdrivingmanufacturingtowardinegrationintoacoherentsystem,acontinuousprocessinwhichpartsdonotspentasmuchas95%ofproductiontimebeingmovedaroundorwaitingtobeworkedon.Thecomputeristhekeytoeachofthesetwinrequirements.Itistheonlytoolthatcanprovidethequickreflexes,theflexibilityandseed,tomeetadiversifiedmarket.Anditistheonlytoolthatenablesthedetailedanalysisandtheaccessibilityofaccuratedatanecessaryfortheintegrationofthemanufacturingsystem.Itmaywellbethat,inthefuture,thecomputermaybeessentialtoacompanyssurvial.Manyoftodaysbusinesseswillfadeawaytobereplacedbymore-productivecombinations.Suchmore-productivecombinationsaresuperquality,superproductivityplants.Thegoalistodesignandoperateaplantthatwouldproduce100%satisfactorypartswichgoodproductivity.Asophisticated,competitiveworldisrequiringthatmanufacturingbegintosettleformore,tobecomeitselfsophisticated.Tomeetcompetition,forexample,acompanywillhavetomeetthesomewhatconflictingdemandsforgreaterproductdiversification,higherquality,improvedproductivity,higherquality,improvedproductivityandprices.Thecompanythatseekstomeetthesedemandswillneedasophisticatedtool,onethatwillallowittorespondquicklytocustomerneedswhilegettingthemostoutofitsmanufacturingresources.Thecomputeristhattool.Becominga“superquality,superproductivity”plantrequirestheintegrationofanextremelycomplexsystem.Thiscanbeaccomplishedonlywhenallextremelycomplexsystem.Thiscanbeaccomplishedonlywhenallelementsofmanufacturing-design,fabricationandassembly,qualityassurance,management,materialshanding-arecomputerintegrated.Inproductdesign,forexample,interactivecomputer-aided-design(CAD)systemsallowthedrawingandanalysistaskstobeperformedinafractionofthetimeallowthedrawingandanalysistaskstobeperformedinafrationofthetimepreviouslyrequiredandgreateraccuracy.Andprogramsforprototypetestingtestingandevaluationfurtherspeedthedesignprocess.Inmanufacturingplanning,computer-aidedprocessplanningpermitstheselection,fromthousandsofpossiblesequencesandschedules,oftheoptimumprocess.Ontheshopfloor,distributedintlligenceintheformofmicroprocessorscontrols,runsautomatedloadingandunloadingequipment,andcollectsdataoncurrentshopconditions.Butsuchisolatedrevolutionsarenotenough.Whatisnendedisatotallyautomatedsystem,linkedbycommonsoftwarefromfrontdoortoback.Thebenefitsrangethoughoutthesystem.Essentially,computerintegrationprovideswidelyandinstantaneouslyavailable,accurateinformation,improvingcommunicationbetweendepartments,permittingtightercontrol,andgenerallyenhancingtheoverallqualityandefficiencyoftheentiresystem.Improvedcommunicationcanmean,forexample,designsthataremoreproducible.TheNCprogrammerandthetooldesignerhaveachangtoinfluencetheproductdesigner,andviceversa.Engineeringchanges,canbereduced,andthosethatarerequiredcanbehandledmoreefficiently.Notonlydosethecomputerpermitthemtobespecicifiedmorequickly,butitalsoalerssubsequentusersofthedatatothefactthatachangehasbeenmade.Theinstantaneousupdatingofproduction-controldatapermitsbetterplanningandmore-effectivescheduling.Expensiveequipment,therefore,isusedmoreproductively,andpartsmovemoreefficientlythroughproduction,reducingwork-in-processcoats.Productquality,too,canbeimproved.Notonlyaremore-accuratedesignsproduced,forexample,buttheuseofdesigndatabythequality-assurancedepartmenthelpseliminateerrorsduetomisunderstandings.Peopleareenabledtodotheirjobsbetter.Byeliminatingtediouscalculationsandpaperworknottomentiontimewastedsearchingforinformationthecomputernotonlyallowsworkerstobemoreproductivebutalsofreesthemtodowhatonlyhumanbeingcando:thinkcreatively.Computerintegrationmayalsolurenewpeopleintomanufacturing.Peopleareattractedbecausetheywanttoworkinamodern,technologicallysophisticatedenviroment.Inmanufacturingengineering,CAD/CAMdecreasestool-design,NC-programming,andplanningtimeswhilespeedingtheresponserate,whichwilleventuallypermitin-housstafftoperformworkthatiscurrentlybeingcontractedout.2.CAD/CAMCAD/CAMisatermwhichmeanscomputer-aidedandcomputer-aidedmanufacturing.itisthetechnologyconcernedwiththeuseofdigitalcomputerstoperformcertainfunctionsindesignandproduction.Thistechnologyismovinginthedirectionofgreaterintegrationofdesignandmanufacturing,twoactivitieswhichhavetraditionallybeentreatedasdistinctandseparatefunctionsinaproductionfirm.Ultimately,CAD/CAMwillprovidethetechnologybaseforthecomputer-integratedfactoryofthefuture.Computer-aideddesign(CAD)canbedefinedastheuseofcomputerstytemstoassistinthecreation,modification,analysis,oroptimizationofadesign.Thecomputersystemsconsistofthehardwareandsoftwaretoperformthespecializeddesignfunctionsrequiredbytheparticularuserfirm.TheCADhardwaretypicallyincludedthecomputer,oneormoregraphicsdisplayterminals,keyboards,andotherperipheralequipment.TheCADsoftwareconsistsofthecomputerprogramstoimplementcomputergraphicstofacilitatetheengineeringfunctionsoftheusercompany.Examplesoftheseapplicationprogramsincludestress-strainanalysisofcomponents,dynamicresponseofmechanisms,heat-transfercalculations,andnumericalcontrolpartprogrammingThecollectionofapplicationprogramswillvaryfromoneuserfirmtothenextbecausetheirproductlines,manufacturingprocesses,andcustomermarketsaredifferentThesefactorsgiverisetodifferencesinCADsystemrequirements.Computer-aidedmanufacturing(CAM)canbedefinedastheuseofcomputersystemstoplan,manufacturingplantthrougheitherdirectorindirectcomputerinterfacewiththeplansproductionresources.Asindicatedbythedefinition,theapplicationsofcomputer-aidedmanufacturingfallintotwobroadcategories:1.Computermonitoringandcontrol.2.Manufacturingsupportapplications.Thedistinctionbetweenthetwocategoriesisfundamentaltoanunderstand-ingofcomputer-aidedmanufacturing.Inadditiontotheapplicationsinvolvingadirectcomputer-processinterfaceforthepurposeofprocessmonitoringandcontrol,computer-aidedmanufacturingalsoincludesindirectapplicationsinwhichthecomputerservesasupportroleinthemanufacturingoperationsoftheplant.Intheseapplications,thecomputerisnotlinkeddirectlytothemanufacturingprocess.Instead,thecomputerisused“off-line”toprovideplans,schedules,forecasts,instructions,andinformationbywhichthefirmsproductionresourcescanbemanagedmoreeffectively.Theformoftherelationshipbetweenthecomputerandtheprocessisrepresentedsymbolicallyinthefiguregivenbelow.Dashedlinesareusedtoindicatethatthecomm