外文翻譯--計算機輔助工藝過程設(shè)計.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.計算機輔助工藝過程設(shè)計根據(jù)工具與制造工程師手冊，工藝過程是能夠經(jīng)濟(jì)地和有競爭力地將產(chǎn)品制造出來的一整套方法。它主要由選擇、計算和建立工藝文件組成。對加工方法、機床、刀具、工序和順序必須進(jìn)行選擇。對于一些參數(shù)如進(jìn)給量、速度、公差、尺寸和成本等應(yīng)該進(jìn)行計算。最后，應(yīng)該制訂帶工序簡圖的工藝過程卡片，工序卡片和工藝路線等方面的工藝文件。工藝過程是產(chǎn)品設(shè)計和制造的中間環(huán)節(jié)。那么，它是如何將設(shè)計與制造聯(lián)接起來的呢?大部分制造工程師都會同意這個看法，即如果10個不同的工藝人員編制同一個零件的工藝規(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，事實上也不能保證它們中的任何一個方案是由加工這個零件的最好的方法組成的。在目前的制造過程中的一個更為混亂的事情是，對于一個零件來說，現(xiàn)在所編制的工藝規(guī)程可能與以前在制造過程中所編制的同一個零件或者相似零件的工藝規(guī)程相差很多，而且這個工藝規(guī)程可能再也不會應(yīng)用于同一個零件或者相似零件。這說明很多工作成果都被浪費了，而且在工藝路線、工藝裝備、對工人的要求和成本等方面都不一致，甚至對外購件的要求都不一樣。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l(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。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)、機器的規(guī)格、工藝裝備的清單、原材料庫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，而計算機是完成這項工作的一個理想助手。在設(shè)計工藝過程時應(yīng)