計(jì)算機(jī)輔助制造外文文獻(xiàn)翻譯、中英文翻譯

IntegratedComputerAidedManufacturing1.INTRODUCTIONToday’sindustrycompetesinatrulyinternationalmarketplace.Efficienttransportationnetworkshavecreateda“worldmarket”inwhichweparticipateonadailybasis.Foranyindustrialcountrytocompeteinthismarket,itmusthavecompaniesthatprovideeconomichigh-qualityproductstotheircustomersinatimelymanner.Theimportanceofintegratingproductdesignandprocessdesigntoachieveadesignforproductionsystemcannotbeoveremphasized.However,evenonceadesignisfinalized,manufacturingindustriesmustbewillingtoaccommodatetheircustomersbyallowinglast-minuteengineering-designchangeswithoutaffectingshippingschedulesoralteringproductquality.MostU.S.-basedmanufacturingcompanieslooktowardCAD/CAMandCIMtoprovidethisflexibilityintheirmanufacturingsystem.Today,theuseofcomputersinmanufacturingiscommon.Manufacturingsystemarebeingdesignedthatnotonlyprocesspartsautomatically,butalsomovethepartsfrommachinetomachineandsequencetheorderingofoperationsinthesystem.Figure1containsaplotoftheeconomicregionsofmanufacturing.ItshouldbenotedthatmanualhandcraftedgoodswillalwayshaveamarketintheUnitedStatesaswellasabroad.Thisisalsotrueofindustrialproducts—therewillcontinuetobeaneedforspecialone-of-a-kinditems.Thespectrumofone-of-a-kindgoodsthroughhigh-volumegoodsdictatesthatavarietyofmanufacturingmethodsbeusedtomeetourvariousindustrialneeds.Someofthesesystemswilllooklikethefactoriesthatourgrandparentslaboredin,whereasotherswilltakeonafuturisticlook.Inthefollowingsections,adiscussionofflexiblemanufacturingsystemsispresented.Figure1Volumeversusvarietyregionsforeconomicmanufacturing(CourtesyofCincinnatiMilacron.)2.FLEXIBLEMANUFACTURINGSYSTEMSAflexiblemanufacturingsystem,orFMSastheyaremorecommonlyknown,isareprogram-ablemanufacturingsystemcapableofproducingavarietyofproductsautomatically.SinceHenryFordfirstintroducedandmodernizedthetransferline,wehavebeenabletoperformavarietyofmanufacturingoperationsautomatically.However,alteringthesesystemstoaccommodateevenminorchangesintheproducthasbeenquitetaxing.Wholemachinesmighthavetobeintroducedtothesystemwhileothermachinesorcomponentsaremodifiedorretiredtoaccommodatesmallchangesinaproduct.Intoday’scompetitivemarketplace,itisnecessarytoaccommodatecustomerchangesorthecustomerwillfindsomeoneelsewhowillaccommodatethechanges.Conventionalmanufacturingsystemshavebeenmarkedbyoneoftwodistinctfeatures:Jobshoptypesystemswerecapableofproducingavarietyofproduct,butatahighcost.Transferlinescouldproducelargevolumesofaproductatareasonablecost,butwerelimitedtotheproductionofone,two,orveryfewdifferentparts.Theadventofnumericalcontrol(NC)androboticshasprovideduswithreprogrammingcapabilitiesatthemachinelevelwithminimumsetuptime.NCmachinesandrobotsprovidethebasicphysicalbuildingblocksforre-programmablemanufacturingsystems.2.1.FMSEquipment2.1.1MachinesInordertomeettherequirementsofthedefinitionofanFMS,thebasicprocessinginthesystemmustbeautomated.Becauseautomationmustbeprogrammableinordertoaccommodateavarietyofproduct-processingrequirements,easilyalterableaswellasversatilemachinesmustperformthebasicprocessing.Forthisreason,CNCturningcenters,CNCmachiningcenters,androboticworkstationscomprisethemajorityofequipmentinthesesystems.Thesemachinesarenotonlycapableofbeingeasilyreprogrammed,butarealsocapableofaccommodatingavarietyoftoolingviaatoolchangerandtool-storagesystem.ItisnotunusualforaCNCmachiningcentertocontainto12ormoretools(right-handturningtools,left-handturningtools,boringbars,drills,andsoon).TheautomatictoolchangerandstoragecapabilitiesofNCmachinesmakethemnaturalchoicesformaterial-processingequipment.Partsmustalsobemovedbetweenprocessingstationsautomatically.Severaldifferenttypesofmaterial-handlingsystemsareemployedtomovethesepartsfromstationtostation.Theselectionofthetypeofmaterial-handlingsystemisafunctionofseveralsystemfeatures.Thematerial-handlingsystem,first,mustbeabletoaccommodatetheloadandbulkofthepartandperhapsthepartfixture.Large,heavypartsrequirelarge,powerfulhandlingsystemssuchasrollerconveyorsguidedvehiclesortrack-drivenvehiclesystems.Thenumberofmachinestobeincludedinthesystemandthelayoutofthemachinesalsopresentanotherdesignconsideration.Ifsinglematerialhandlermustbeatleastaslargeasthephysicalsystem.Arobotisnormallyonlycapableofaddressingoneortwomachinesandload-and-unloadstation.Aconveyororautomaticguidevehicle(AGV)systemcanbeexpandedtoincludemilesoffactoryfloor.Thematerial-handlingsystemmustalsobecapableofmovingpartsfromonemachinetoanotherinatimelymanner.Machinesinthesystemwillbeunproductiveiftheyspendmuchoftheirtimewaitingforpartstobedeliveredbythematerialhandler.Ifmanypartsareincludedinthesystemandtheyrequirefrequentvisitstomachines,thenthematerial-handlingsystemmustbecapableofsupportingtheseactivities.Thisusuallycanbeaccommodatedbyusingeitheraveryfasthandlingdeviceofbyusingseveraldevicesinparallel,forexample,insteadofusingasinglerobottomovepartstoallthemachinesinthesystem,arobotwouldonlysupportasinglemachine.2.1.2Toolingandfixtures.VersatilityisthekeytomostFMSs,andassuchthetoolingusedinthesystemmustbecapableofsupportingavarietyofproductsorparts.TheuseofspecialformingtoolsinanFMSisnottypicalinpractice.Thecontoursobtainedbyusingformingtoolscanusuallybeobtainedthroughacontour-controlNCsystemandastandardmill.Thestandardmillthencanbeusedforavarietyofpartsratherthantoproduceasinglespecialcontour.Aneconomicofthecostandbenefitsofanyspecialtoolingisnecessarytodeterminethebesttoolingcombination.However,becauseNCmachineshavealimitedoftoolsthatareaccessible,veryspecialtoolsshouldbeincluded.OneofthecommonlyneglectedaspectsofanFMSisthefixturingused.Becausefixturesarepartofthetoolingofthesystem,onecouldarguethattheyshouldalsobestandardforthesystem.Workoncreating“flexiblefixtures”thatcouldbeusedtosupportavarietyofcomponentshasonlyrecentlybegun.SeeChapter5.OneuniqueaspectofmanyFMSsisthatthepartisalsomovedaboutthesysteminthefixture(orpalletfixture).Fixturesaremadetothesamedimensionssothatthematerial-handlingsystemcanbespecializedtohandleasinglegeometry.Partsarelocatedpreciselyonthefixtureandmovedfromonestationtoanotheronthefixture.Fixturesofthistypeareusuallycalledpalletfixtures,orpallets.Manyofthepalletfixturesemployedtodayhavestandard“T-slots”cutinthem,andusestandardfixturekitstocreatethepart-locatingand-holdingenvironmentneedformachining.3.COMPUTERCONTROLOFFLEXIBLEMANUFACTURINGSYSTEMS3.1FMSArchitectureAnFMSisacomplexnetworkofequipmentandprocessesthatmustbecontrolledviaacomputerornetworkofcomputers.InordertomakethetaskofcontrollinganFMSmoretractable,thesystemisusuallydividedintoatask-basedhierarchy.OneofthestandardhierarchiesthathaveevolvedistheNationalInstituteofStandardsandTechnology(NIST)factory-controlhierarchy.(NISTwasformerlytheNationalBureauofstandards.NBS.)ThishierarchyconsistsoffivelevelsandisillustratedinFigures2andFigures3Thesystemconsistsofphysicalmachiningequipmentatthelowestlevelofthesystem.Workstationequipmentresidesjustabovetheprocesslevelandprovidesintegrationandinterfacefunctionsfortheequipment.Forinstancepalletfixturesandprogrammingelementsarepartoftheworkstation.Theworkstationtypicallyprovidesbothman-machineinterfaceaswellasmachine-partinterface.Off-lineprogrammingsuchasAPTforNCorAMLforrobotresidesattheworkstationlevel.Thecellistheunitinthehierarchywhereinteractionbetweenmachinesbecomespartofthesystem.Thecellcontrollerprovidestheinterfacebetweenthemachinesandmaterial-handlingsystem.Assuch,thecellcontrollerisresponsibleforsequencingandschedulingpartsthroughthesystem.Attheshoplevelintegrationofmultiplecellsoccursaswellastheplanningandmanagementofinventory.TheFigure3Therelationshipbetweenthedata-administration(DAS)intheNISTarchitecture:(1)thetopologiesoftheIntegratedManufacturingDataAdministrationSystem(IMDAS)data-administrationsystem;(2)thenetworkdata-communicationnetwork;(3)thehierarchicalsystemofdata-drivencontrol:datapreparationisimpliedin(4)thefacilitylevelofcontrolfacilitylevelistheplaceinthehierarchywherethemasterproductionscheduleisconstructedandmanufacturingresourceplanningisconducted.Orderingmaterialsplanninginventoriesandanalyzingbusinessplansarepartoftheactivitiesthataffecttheproductionsystem.Poorbusinessandmanufacturingplanswillincapacitatethemanufacturingsystemjustassurlytheunavailabilityofamachine.3.2FMSSchedulingandcontrolFlexiblemanufacturingsystems,likeothermanufacturingsystemcandiffersignificantlycomplexity.Thiscomplexityisnotonlydeterminedbythenumberofmachinesandthenumberofpartsresidentinthesystem,butalsobythecomplexityofpartsandcontrolrequirementsofthespecificequipment.SomeFMSsrequireonlyasimpleprogrammablecontrollertoregulatetheflowofpartsthoughthesystem,whereasothersrequiresophisticatedcomputercontrolsystems.Inthefollowingsections,exampleofFMSsandtheircontrolarepresented.ThemostsimpleFMSconsistsofaprocessingmachine,aload/unloadarea,andamaterialhandler(aone-machinesystemisthemostsimpleFMSthatcanbeconstructed).Operationofthissystemconsistsofloadingthepart(s)thatmovedownaconveyorthemachine.Oncethepartisloadedontothemachine,therobotisretractedtoa“safeposition”andthemachiningbegins.Althoughthisisaverysimplesystem,itillustratesseveralinterestingdesignandcontroldecisionsthatmustbeconsidered.Ifonlyasinglepartistobeprocessedinthesystem,aminimumnumberofswitchesandsensorsnecessaryforthesystem.Onerequirementofthesystemisthatthepartsontheconveyorallhavetobeorientedinthesameway.ThisisrequiredsothattherobotcanpickupthepartanddeliverittotheNCmachineinthesameorientationeverytime.Aproximityswitchormicro-switchisrequiredattheendoftheconveyortodetectwhenapartisresident,andonthemachineforthesamepurpose.計(jì)算機(jī)輔助制造1.緒論當(dāng)今的工業(yè)的競(jìng)爭(zhēng)已經(jīng)是真正意義上的國(guó)際市場(chǎng)競(jìng)爭(zhēng)。高效的運(yùn)輸網(wǎng)絡(luò)建立了一個(gè)我們每天都要參與的“世界市場(chǎng)”。對(duì)于任何工業(yè)化國(guó)家要參與這個(gè)市場(chǎng)競(jìng)爭(zhēng)，就必須采用一種適時(shí)的方式為其客戶(hù)提供經(jīng)濟(jì)、優(yōu)質(zhì)的產(chǎn)品。將產(chǎn)品設(shè)計(jì)和過(guò)程設(shè)計(jì)進(jìn)行集成的重要性，在產(chǎn)品系統(tǒng)被怎么強(qiáng)調(diào)都不為過(guò)。但是，即使一種設(shè)計(jì)最終被落實(shí)，制造業(yè)者一定愿意通過(guò)允許最后的工程設(shè)計(jì)變化，而沒(méi)有通過(guò)影響裝運(yùn)進(jìn)度表，或者改變產(chǎn)品質(zhì)量來(lái)適應(yīng)他們的用戶(hù)。大多數(shù)美國(guó)的生產(chǎn)公司基于趨向計(jì)算機(jī)輔助設(shè)計(jì)（CAD）/計(jì)算機(jī)輔助制（CAM）和CIM為他們的制造系統(tǒng)提供靈活性。今天，計(jì)算機(jī)用于制造已經(jīng)很平常?，F(xiàn)在不僅為零件生產(chǎn)設(shè)計(jì)制造系統(tǒng)，而且為零件從一臺(tái)機(jī)器運(yùn)送到另一臺(tái)機(jī)器的命令順序設(shè)計(jì)了制造系統(tǒng)，如圖（1），它還包含一個(gè)經(jīng)濟(jì)區(qū)域的制造經(jīng)濟(jì)計(jì)劃在美國(guó)和其他國(guó)家，手工產(chǎn)品總是還有一些市場(chǎng)的，此外真正的工業(yè)產(chǎn)品對(duì)于特殊的“one-of-a-kind”技術(shù)項(xiàng)目還是需要的。“one-of-a-kind”通過(guò)大量的貨物來(lái)表明、各種各樣的工業(yè)需要各種各樣的加工方法。有些系統(tǒng)將看起來(lái)像我們的祖父母曾經(jīng)工作過(guò)的工廠，而其它則呈現(xiàn)出一種未來(lái)派的情景。在后文中，我們將展開(kāi)討論柔性制造系統(tǒng)。圖（1）2.柔性制造系統(tǒng)柔性制造系統(tǒng)（FMS）像人們通常知道的那樣的，能使用一個(gè)可編程的制造系統(tǒng)自動(dòng)地生產(chǎn)各種各樣的產(chǎn)品。自從亨利·福特率先提出并且使流水生產(chǎn)線(xiàn)實(shí)現(xiàn)現(xiàn)代化，我們就已經(jīng)能自動(dòng)執(zhí)行多種生產(chǎn)的生產(chǎn)。不過(guò)，改變這些系統(tǒng)甚至只作較小的變動(dòng)，這些產(chǎn)品的生產(chǎn)都會(huì)變得相當(dāng)繁重。當(dāng)其他機(jī)器或者零部件要經(jīng)過(guò)修理或者廢棄，以適應(yīng)這種蕭蕭的變化，整個(gè)機(jī)器才可能被引進(jìn)到系統(tǒng)。在今天的競(jìng)爭(zhēng)性市場(chǎng)里，能適應(yīng)客戶(hù)的各種變化是很必要的。傳統(tǒng)的制造系統(tǒng)以特征可劃分為以下兩種：

1.加工車(chē)間類(lèi)型系統(tǒng)能生產(chǎn)多種產(chǎn)品，但是費(fèi)用高。

2.流水線(xiàn)能以合理費(fèi)用生產(chǎn)能大量產(chǎn)品，但是僅局限于幾種不同零件的生產(chǎn)。

數(shù)控(NC)和機(jī)器人技術(shù)的時(shí)代已經(jīng)來(lái)臨，這為我們提供了在最小準(zhǔn)備時(shí)間里，使機(jī)器的程序重新調(diào)定。NC機(jī)床和機(jī)器人是重新可編程序的制造系統(tǒng)的基本物理組成部分。2.1.柔性制造系統(tǒng)的設(shè)備2.1.1機(jī)床為了滿(mǎn)足柔性制造系統(tǒng)定義的要求，該系統(tǒng)的基本工藝應(yīng)實(shí)現(xiàn)自動(dòng)化。因?yàn)樽詣?dòng)化必須是可編程的，以適應(yīng)不同的產(chǎn)品要求，而易于改變，以及通用機(jī)床必須執(zhí)行這些工藝。計(jì)算機(jī)數(shù)控（CNC）車(chē)削中心、計(jì)算機(jī)數(shù)控（CNC）加工中心、及機(jī)器人工作站構(gòu)成了這些設(shè)備。這些機(jī)器不僅僅是易于重新編程，同時(shí)也適應(yīng)置于刀具存儲(chǔ)系統(tǒng)及刀具更換器中的不同刀具。通常CNC加工中心備有60多把或更多刀具（銑刀、鉆頭、鏜刀等）。對(duì)于CNC車(chē)削中心，備有12把或更多的刀具（右車(chē)刀、左車(chē)刀、鏜桿、鉆頭等）。書(shū)動(dòng)機(jī)床的自動(dòng)換刀器及刀庫(kù)使它們對(duì)材料的工藝裝備作出自然的選擇。零件必須在加工站點(diǎn)之間自動(dòng)化的移動(dòng)，采用了數(shù)種不同的物料輸送系統(tǒng)，把這些零件從一個(gè)站點(diǎn)輸送到另一個(gè)站點(diǎn)。物料輸送系統(tǒng)的選擇是數(shù)種系統(tǒng)特征函數(shù)。首先，物料輸送系統(tǒng)的選擇必須適應(yīng)零件（或許是零件的夾具）的負(fù)荷及批量。大型的、重型的零件需要大型的、強(qiáng)力的輸送系統(tǒng)，如滾子輸送、導(dǎo)向小車(chē)、軌道驅(qū)動(dòng)車(chē)輛系統(tǒng)。構(gòu)成的機(jī)床數(shù)量及機(jī)床布置也提供了另一種設(shè)計(jì)上的考慮。如果用單一的物料輸送機(jī)來(lái)運(yùn)送零件到系統(tǒng)內(nèi)的所有機(jī)床，則運(yùn)輸機(jī)的工作覆蓋面至少必須是和整個(gè)系統(tǒng)一樣大。通常一臺(tái)機(jī)器人定位于一兩臺(tái)機(jī)床或一個(gè)裝卸站。一臺(tái)輸送機(jī)或自動(dòng)導(dǎo)向車(chē)可以擴(kuò)大到數(shù)英里的工廠區(qū)域。物料輸送也可以以即時(shí)的方式將零件從一臺(tái)機(jī)床輸送到另一臺(tái)機(jī)床。如果系統(tǒng)內(nèi)的機(jī)床耗費(fèi)大量的時(shí)間在等待輸送零件的到來(lái)，則其生產(chǎn)率是不會(huì)高地。如果有許多種零件包括在系統(tǒng)內(nèi)，而且這些零件要經(jīng)常輸送到機(jī)床上，物料系統(tǒng)要能夠支持這些活動(dòng)。通常由采用極快的輸送裝置