外文翻譯--計(jì)算機(jī)輔助工藝過(guò)程設(shè)計(jì).doc

Computer-AidedProcessPlanningAccordingtotheTool&ManufacturingEngineersHandbook,processplanningisthesystematicdeterminationofthemethodsbywhichaproductistobemanufacturedeconomicallyandcompetitively.Itessentiallyinvolvesselection,calculation,anddocumentation.Processes,machines,tools,operations,andsequencesmustbeselected.Suchfactorsasfeeds,speeds,tolerances,dimensions,andcostsmustbecalculated.Finally,documentsintheformofillustratedprocesssheets,operationsheets,andprocessroutesmustbeprepared.Processplanningisanintermediatestagebetweendesigningandmanufacturingtheproduct.Buthowwelldoesitbridgedesignandmanufacturing?Mostmanufacturingengineerswouldagreethat,iftendifferentplannerswereaskedtodevelopaprocessplanforthesamepart,theywouldprobablycomeupwithtendifferentplans.Obviously,alltheseplanscannotreflectthemostefficientmanufacturingmethods,and,infact,thereisnoguaranteethatanyoneofthemwillconstitutetheoptimummethodformanufacturingthepart.Whatmaybeevenmoredisturbingisthataprocessplandevelopedforapartduringacurrentmanufacturingprogrammaybequitedifferentfromtheplandevelopedforthesameorsimilarpartduringapreviousmanufacturingprogramanditmayneverbeusedagainforthesameorsimilarpart.Thatrepresentsalotofwastedeffortandproducesagreatmanyinconsistenciesinrouting,tooling,laborrequirements,costing,andpossiblyevenpurchaserequirements.Ofcourse,processplansshouldnotnecessarilyremainstatic.Aslotsizeschangeandnewtechnology,equipment,andprocessesbecomeavailable,themosteffectivewaytomanufactureaparticularpartalsochanges,andthosechangesshouldbereflectedincurrentprocessplansreleasedtotheshop.Aplannermustmanageandretrieveagreatdealofdataandmanydocuments，includingestablishedstandards，machinabilitydata，machinespecifications，toolinginventories，stockavailability，andexistingprocessplansThisisprimarilyaninformationhandlingjob，andthecomputerisanidealcompanionThereisanotheradvantagetousingcomputerstohelpwithprocessplanningBecausethetaskinvolvesmanyinterrelatedactivities，determiningtheoptimumplanrequiresmanyiterations.Sincecomputerscanreadilyperformvastnumbersofcomparisons，manymorealternativeplanscanbeexploredthanwouldbepossiblemanuallyAthirdadvantageintheuseofcomputer-aidedprocessplanningisuniformity.SeveralspecificbenefitsCanbeexpectedfromtheadoptionofcomputer-aidedprocessplanningtechniques：1Reducedclericaleffortinpreparationofinstructions2Fewercalculationerrorsduetohumanerror3.Feweroversightsinlogicorinstructionsbecauseofthepromptingcapabilityavailablewithinteractivecomputerprograms4Immediateaccesstouptodateinformationfromacentraldatabase5Consistentinformation，becauseeveryplanneraccessesthesamedatabase6.Fasterresponsetochangesrequestedbyengineersofotheroperatingdepartments7AutomaticUseofthelatestrevisionofapartdrawing8.Moredetailed，moreuniformprocess-planstatementsproducedbywordprocessingtechniques.9Moreeffectiveuseofinventoriesoftools，gages，andfixturesandaconcomitantreductioninthevarietyofthoseitems.10.Bettercommunicationwithshoppersonnelbecauseplanscanbemorespecificallytailoredtoaparticulartaskandpresentedinunambiguous，provenlanguage.11.Betterinformationforproductionplanning,includingcutter-life,forecasting,materials-requirementsplanning,scheduling,andinventorycontrol.MostimportantforCIM,computer-aidedprocessplanningproducesmachine-readabledatainsteadofhandwrittenplans.SuchdatacanreadilybetransferredtoothersystemswithintheC1Mhierarchyforuseinplanning.Therearebasicallytwoapproachestocomputer-aidedprocessplanning:variantandgenerative.Inthevariantapproach,asetofstandardprocessplansisestablishedforallthepartsfamiliesthathavebeenidentifiedthroughgrouptechnology.Thestandardplansarestoredincomputermemoryandretrievedfornewpartsaccordingtotheirfamilyidentification.Again,GThelpstoplacethenewpartinanappropriatefamily.Thestandardplanistheneditedtosuitthespecificrequirementsofaparticularjob.Inthegenerativeapproach,anattemptismadetosynthesizeeachindividualplanusingappropriatealgorithmsthatdefinethevarioustechnologicaldecisionsthatmustbemadeinthecourseofmanufacturing.Inatrulygenerativeprocess-planningsystem,thesequenceofoperations,aswellasallthemanufacturing-processparameters,wouldbeautomaticallyestablishedwithoutreferencetopriorplans.Initsultimaterealization,suchanapproachwouldbeuniversallyapplicable:presentanyplantothesystem,andthecomputerproducestheoptimumprocessplan.Nosuchsystemexists,however.Socalledgenerativeprocess-planningsystems-andprobablyfortheforeseeablefuture-arestillspecializedsystemsdevelopedforaspecificoperationoraparticulartypeofmanufacturingprocess.Thelogicisbasedonacombinationofpastpracticeandbasictechnology.計(jì)算機(jī)輔助工藝過(guò)程設(shè)計(jì)根據(jù)工具與制造工程師手冊(cè)，工藝過(guò)程是能夠經(jīng)濟(jì)地和有競(jìng)爭(zhēng)力地將產(chǎn)品制造出來(lái)的一整套方法。它主要由選擇、計(jì)算和建立工藝文件組成。對(duì)加工方法、機(jī)床、刀具、工序和順序必須進(jìn)行選擇。對(duì)于一些參數(shù)如進(jìn)給量、速度、公差、尺寸和成本等應(yīng)該進(jìn)行計(jì)算。最后，應(yīng)該制訂帶工序簡(jiǎn)圖的工藝過(guò)程卡片，工序卡片和工藝路線等方面的工藝文件。工藝過(guò)程是產(chǎn)品設(shè)計(jì)和制造的中間環(huán)節(jié)。那么，它是如何將設(shè)計(jì)與制造聯(lián)接起來(lái)的呢?大部分制造工程師都會(huì)同意這個(gè)看法，即如果10個(gè)不同的工藝人員編制同一個(gè)零件的工藝規(guī)程，他們很可能得出10種不同的方案。顯然，并不是所有這些方案都能反映最適當(dāng)?shù)闹圃旆椒?，而且，事?shí)上也不能保證它們中的任何一個(gè)方案是由加工這個(gè)零件的最好的方法組成的。在目前的制造過(guò)程中的一個(gè)更為混亂的事情是，對(duì)于一個(gè)零件來(lái)說(shuō)，現(xiàn)在所編制的工藝規(guī)程可能與以前在制造過(guò)程中所編制的同一個(gè)零件或者相似零件的工藝規(guī)程相差很多，而且這個(gè)工藝規(guī)程可能再也不會(huì)應(yīng)用于同一個(gè)零件或者相似零件。這說(shuō)明很多工作成果都被浪費(fèi)了，而且在工藝路線、工藝裝備、對(duì)工人的要求和成本等方面都不一致，甚至對(duì)外購(gòu)件的要求都不一樣。當(dāng)然工藝規(guī)程不應(yīng)該是一成不變的。隨著產(chǎn)品批量的變化和新技術(shù)、新設(shè)備、新的加工方法的出現(xiàn)，加工制造某一特定零件最適當(dāng)?shù)姆椒ㄒ矔?huì)發(fā)生變化，而且這些變化應(yīng)該在車間目前使用的加工工藝規(guī)程中反映出來(lái)。工藝人員應(yīng)該管理和檢索大量的數(shù)據(jù)和很多文件，其中包括：已經(jīng)建立了的標(biāo)準(zhǔn)、可加工性數(shù)據(jù)、機(jī)器的規(guī)格、工藝裝備的清單、原材料庫(kù)存量和一些目前正在應(yīng)用的工藝文件。這主要是一些信息處理工作，而計(jì)算機(jī)是完成這項(xiàng)工作的一個(gè)理想助手。在設(shè)計(jì)工藝過(guò)程時(shí)應(yīng)