机械毕业设计英文外文翻译255计算机与制造业Word下载.docx
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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