机械毕业设计英文外文翻译255计算机与制造业.docx

机械毕业设计英文外文翻译255计算机与制造业.docx

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机械毕业设计英文外文翻译255计算机与制造业

附录2

英语原文

TheComputerandManufacturing

ComputerAidedDesign

ThecomputerisbringingmanufacturingintotheInformationAge.Thisnewtool,alongfamiliaroneinbusinessandmanagementoperations,ismovingintothefactory,anditsadventischangingmanufacturingascertainlyasthesteamenginechangedit100yearsago.

Thebasicmetalworkingprocessesarenotlikelytochangefundamentally,buttheirorganizationandcontroldefinitelywill.

INonerespect,manufacturingcouldbesaidtobecomingfullcircle.Thefirstmanufacturingcouldwasacottageindustry:

thedesignerwasalsothemanufacturer,conceivingandfabricatingproductsoneatatime.Eventually,theconceptoftheinterchangeabilityofpartswasdeveloped,productionwasseparatedintospecializedfunctions,andidenticalpartswereproducedthousandsatatime.

Today,althoughthedesignerandmanufacturermaynotbecomeoneagain,thefunctionsarebeingdrawncloseinthemovementtowardanintegratedmanufacturingsystem,

Itisperhapsironicthat,atatimewhenthemarketdemandahighdegreedofproductdiversification,thenecessityforincreasingproductivityandreducingcostsisdrivingmanufacturingtowardintegrationintoacoherentsystem,acontinuousprocessinwhichpartsdonotspendasmuchas95%ofproductiontimebeingmovedaroundorwaitingtobeworkedon.

Thecomputeristhekeytoeachofthesetwinrequirements.Itistheonlytoolthatcanprovidethequickreflexes,theflexibilityandspeed,tomeetadiversifiedmarket.Anditistheonlytoolthatenablesthedetailedanalysisandtheaccessibilityofaccuratedatanecessaryfortheintegrationofthemanufacturingsystem.

Itmaywellbethat,inthefuture,thecomputermaybeessentialtoacompany’ssurvival.Manyoftoday’sbusinesseswillfadeawaytobereplacedbymore-productivecombinations.Suchmore-productivecombinationsaresuper-quality,super-productivityplants.Thegoalistodesignandoperateaplantthatwouldproduce100%satisfactorypartswithgoodproductivity.

Asophisticated,competitiveworldisrequiringthatmanufacturingbegintosettleformore,tobecomeitselfsophisticated,Tomeetcompetition,forexample,acompanywillhavetomeetthesomewhatconflictingdemandsforgreaterproductdiversification,higherquality,improvedproductivity,andlowprices.

Thecompanythatseekstomeetthesedemandswillneedasophisticatedtool,onethatwillallowittorespondquicklytocustomerneedswhilegettingthemostoutofitsmanufacturingresources.

Thecomputeristhattool.

Becominga“super-quality,super-productivity”plantrequirestheintegrationofanextremelycomplexsystem.Thiscanbeaccomplishedonlywhenallelementsofmanufacturing—design,fabricationandassembly,qualityassurance,management,materialshandling—arecomputerintegrated.

Inproductdesign,forexample,interactivecomputer-aided-design（CAD）systemsallowthedrawingandanalysistaskstobeperformedinafractionofthetimepreviouslyrequiredandwithgreateraccuracy.Andprogramsforprototypetestingandevaluationfurtherspeedthedesignprocess.

Inmanufacturingplanning,computer-aidedprocessplanningpermitstheselection,fromthousandsofpossiblesequencesschedules,oftheoptimumprocess.

Ontheshopfloor,distributedintelligenceintheformofmicroprocessorscontrolsmachines,runsautomatedloadingandunloadingequipment,andcollectsdataoncurrentshopconditions.

Butsuchisolatedrevolutionsarenotenough.Whatisneededisatotallyautomatedsystem,linkedbycommonsoftwarefromfrontdoortoback.

Thebenefitsrangethroughoutthesystem.Essentially,computerintegrationprovideswidelyandinstantaneouslyavailable,accurateinformation,improvingcommunicationbetweendepartments,permittingtightercontrol,andgenerallyenhancingtheoverallqualityandefficiencyoftheentiresystem.

Improvedcommunicationcanmean,forexample,designsthataremoreproducible.TheNCprogrammerandthetooldesignerhaveachancetoinfluencetheproductdesigner,andviceversa.

Engineeringchanges,thus,canbereduced,andthosethatarerequiredcanbehandledmoreefficiently.Notonlydoesthecomputerpermitthemtobespecifiedmorequickly,butitalsoalertssubsequentusersofthedatatothefactthatachangehasbeenmade.

Theinstantaneousupdatingofproduction-controldatapermitsbetterplanningandmore0effectivescheduling.Expensiveequipment,therefore,isusedmoreproductively,andpartsmovemoreefficientlythroughproduction,reducingwork-in-processcosts.

Productquality,too,canbeimproved.Notonlyaremore-accuratedesignsproduced,forexample,buttheuseofdesigndatabythequality-assurancedepartmenthelpseliminateerrorsduetomisunderstandings.

Peopleareenabledtodotheirjobsbetter.Byeliminatingtediouscalculationsandpaperwork—nottomentiontimewastedsearchingforinformation—thecomputernotonlyallowsworkerstobemoreproductivebutalsofreesthemtodowhatonlyhumanbeingscando:

thinkcreatively.

Computerintegrationmayalsolurenewpeople intomanufacturing.Peopleareattractedbecausetheywanttoworkinamodern,technologicallysophisticatedenvironment.

Inmanufacturingengineering,CAD/CAMdecreasestool-design.NC-programming,andplanningtimeswhilespeedingtheresponserate,whichwilleventuallypermitin-housestafftoperformworkthatiscurrentlybeingcontractedout.

AccordingtotheTool&ManufacturingEngineersHandbook,processplanningisthesystematicdeterminationofthemethodsbywhichaproductistobemanufacturedeconomicallyandcompetitively.Itessentiallyinvolvesselection,calculation,anddocumentation.Processes,machines,tools,andsequencesmustbeselected.Suchfactorsasfeeds,speeds,tolerances,dimensions,andcostsmustbecalculated.Finally,documentsintheformofsetupinstructions,workinstructions,illustratedprocesssheets,androutingsmustbeprepared.Processplanningisanintermediatestagebetweendesigningandmanufacturingtheproduct.Buthowwelldoesitbridgedesignandmanufacturing?

Mostmanufacturingengineerswouldagreethat,iftendifferentplannerswereaskedtodevelopaprocessplanforthesamepart,theywouldprobablycomeupwithtendifferentplans.Obviously,alltheseplanscannotreflectthemostefficientmanufacturingmethods,and,infact,thereisnoguaranteethatanyoneofthemwillconstitutetheoptimummethodsformanufacturingthepart.

Whatmaybeevenmoredisturbingisthataprocessplandevelopedforapartduringacurrentmanufacturingprogrammaybequitedifferentmanufacturingprogramanditmayneverbeusedagainforthesameorsimilarpartduringaprevioussimilarpart.Thatrepresentsalotofwastedeffortandproducesagreatmanyinconsistenciesinrouting,tooling,laborrequirements,costing,andpossiblyevenpurchaserequirements.

Ofcourse,processplansshouldnotnecessarilyremainstatic.Aslotsizeschangeandnewtechnology,equipment,andprocessesbecomeavailable,themosteffectivewaytomanufactureaparticularpartalsochanges,andthosechangesshouldbereflectedincurrentprocessplansreleasedtotheshop.

Aplannermustmanageandretrieveagreatdealofdataandmanydocuments,includingestablishedstandards,machineabilitydata,machinespecifications,toolinginventories,stockavailability,andexistingprocessplans.Thisisprimarilyaninformation-handlingjob,andthecomputerisanidealcompanion.

Thereisanotheradvantagetousingcomputerstohelpwithprocessplanning.Becausethetaskinvolvesmanyinterrelatedactivities,determiningtheoptimumplanrequiresmanyiterations.Sincecomputerscanreadilyperformvastnumbersofcomparisons,manymorealternativeplanscanbeexploredthanwouldbepossiblemanually.

Athirdadvantageintheuseofcomputer-aidedprocessplanningisuniformity.

Severalspecificbenefitscanbeexpectedfromtheadoptionofcomputer-aidedprocess-planningtechniques:

● Reducedclericaleffortinpreparationofinstructions.

●Fewercalculationerrorsduetohumanerror.

● Feweroversightsinlogicorinstructionsbecauseofthepromptingcapabilityavailablewithinteractivecomputerprograms.

● Immediateaccesstoup-to-dateinformationfromacentraldatabase.

● Consistentinformation,becauseeveryplanneraccessesthesamedatabase.

● Fasterresponsetochangesrequestedbyengineeringofotheroperatingdepartments.

● Automaticuseofthelatestrevisionofapartdrawing.

● More-detailed,more-uniformprocess-planstatementsproducedbywordprocessingtechniques.

● More-effectiveuseofinventoriesoftools,gages,andfixturesandaconcomitantreductioninthevarietyofthoseitems.

● Bettercommunicationwithshoppersonnelbecauseplanscanbemorespecificallytailoredtoaparticulartaskandpresentedinunambiguous,provenlanguage.

● Betterinformationforproductionplanning,includingcutter-life,forecasting,materials-requirementsplanning,scheduling,andinventorycontrol.

MostimportantforCIM,computer-aidedprocessplanningproducesmachine-readabledatainsteadofhandwrittenplans.SuchdatacanreadilybetransferredtoothersystemswithintheCIMhierarchyforuseinplanning.

Therearebasicallytwoapproachestocomputer-aidedprocessplanning:

variantandgenerative.

Inthevariantapproach,asetofstandardprocessplansisestablishedforallthepartsfamiliesthathavebeenidentifiedthroughgrouptechnology.Thestandardplansarestoredincomputermemoryandretrievedfornewpartsaccordingtotheirfamilyidentification.Again,GThelpstoplacethenewpartinanappropriatefamily.Thestandardplanistheneditedtosuit