机械专业英语Unit26ComputerAidedManufacturing(2)分析解析

——PartⅢ：COMPUTERIZEDMANUFACTURINGTECHNOLOGIES龙慧Questions:1.WhatarethethreeattributesaCAMsystemshouldhave?2.DescribethethreemajorareasrelatedtothemanufacturingprocessalargescaleCAMsystemhas.3.Whatdoes”those”(inline2,paragraph6)referto?4.GiveanexampleoftheapplicationofadapativeNCsystem?5.Howmanylevelscanthemanufacturingautomationbedefined?Acomputer-aidedmanufacturing(CAM)systemoverseesmanyaspectsofmanufacturebyintroducingahierarchicalcomputerstructuretomonitorandcontrolvariousphasesofthemanufacturingprocess.ConventionalandadaptiveNCsystemsarethepredecessorstolargeCAMsystems.WhereNCconsidersaninformationfeedbackloopconcernedwithdiscreteprocess,CAMdevelopanintegratedinformationnetworkthatmonitorabroadspectrumofinterrelatedtasksandcontrolseachbasedonoverallmanagementstrategy.Unit26Computer-AidedManufacturingAcomputer-aidedmanufacturing(CAM)systemoverseesmanyaspectsofmanufacturebyintroducingahierarchicalcomputerstructuretomonitorandcontrolvariousphrasesofthemanufacturingprocess.ConventionalandadaptiveNCsystemsarethepredecessorstolargeCAMsystems.WhereNCconsidersaninformationfeedbackloopconcernedwithdiscreteprocess,CAMdevelopanintegratedinformationnetworkthatmonitorabroadspectrumofinterrelatedtasksandcontrolseachbasedonoverallmanagementstrategy.一个计算机辅助制造系统通过引进一种分级计算机结构监控制造过程的不同状态来监管制造的各个方面，传统的与自适应的NC系统就是大型CAM系统的原型，在数控考虑了与离散工艺过程相关的信息反馈环节的地方，CAM形成了集成信息网络，以监视更大范围的相互联系的任务，并控制以完全管理策略为基础的每一项任务。Ideally,aCAMsystemshouldhavethreeattributesapplicabletoeachphaseofthemanufacturingprocess:althoughsupervised,aminimumamountofhumaninterventionshouldberequiredforindividualprocesstasks;thesystemshouldbeflexibleandallowprocessestobeindividuallyprogrammed;andtheCAMsystemshouldbeintegrated,withbothengineeringdesignandanalysis,usingacomputer-aideddesign(CAD)system.Variousaspectsofthisidealsystemhavebeensuccessfullyimplemented,butmuchdevelopmentworkcontinuestobecarriedout.理论上，CAM系统应用有三个适用于制造过程中每一状态属性：虽然说过程中各项任务都有监控，但对于个别的过程任务也有或多或少的人工干预；系统应该是柔性的，允许一些过程个别的加以编程；CAM系统应该利用CAD系统将工程设计与工程分析集成起来，这样的理想的系统的不同方面已成功得以实现，但还有更多的开发工作继续在进行。Ideally,aCAMsystemshouldhavethreeattributesapplicabletoeachphaseofthemanufacturingprocess:althoughsupervised,aminimumamountofhumaninterventionshouldberequiredforindividualprocesstasks;thesystemshouldbeflexibleandallowprocessestobeindividuallyprogrammed;andtheCAMsystemshouldbeintegrated,withbothengineeringdesignandanalysis,usingacomputer-aideddesign(CAD)system.Variousaspectsofthisidealsystemhavebeensuccessfullyimplemented,butmuchdevelopmentworkcontinuestobecarriedout.TheCAMHierarchyAlargescaleCAMsystemcontainsahierarchicalstructureoftwoorthreelevelsofcomputersthatareusedtocontrolandmonitorindividualprocesstasks.Asmall(minicomputer)isresponsibleforthemanagementofasingleprocessedinformation.ThisgeneralconfigurationofaCAMhierarchyisillustratedinFig.26.1.一种大型CAM系统含有一种具有两级或三计算的分级结构，以用于监控个别的过程任务，小型或微型计算机负责管理单一的处理任务，这种CAM分级结构的一般形式如图所示。TheCAMHierarchyAlargescaleCAMsystemcontainsahierarchicalstructureoftwoorthreelevelsofcomputersthatareusedtocontrolandmonitorindividualprocesstasks.Asmall(minicomputer)isresponsibleforthemanagementofasingleprocessedinformation.ThisgeneralconfigurationofaCAMhierarchyisillustratedinFig.26.1.AlargescaleCAMsystemencompassesthreemajorareasrelatedtothemanufacturingprocess:productionmanagementandcontrol;engineeringanalysisanddesign;andfinanceandmarketing.Eachiscomprisedofsubtasksthatarecontrolledeitherdirectlyformlargecomputer(e.g.,inventorycontrol),orbyasmallcomputer,asinthecaseofinspectionqualitycontrol.Regardlessofthecontrolmethod,theimportantstrengthofCAMisthatatwowayflowofinformationoccurs.AlargescaleCAMsystemencompassesthreemajorareasrelatedtothemanufacturingprocess:productionmanagementandcontrol;engineeringanalysisanddesign;andfinanceandmarketing.Eachiscomprisedofsubtasksthatarecontrolledeitherdirectlyformlargecomputer(e.g.,inventorycontrol),orbyasmallcomputer,asinthecaseofinspectionqualitycontrol.Regardlessofthecontrolmethod,theimportantstrengthofCAMisthatatwowayflowofinformationoccurs.一个大型CAM系统包含有与制造过程相关的三大模块：产品管理与控制；工程分析与设计；财务与营销。每一个模块又包括一些子任务，这些子任务或者是直接受控于一台大型计算机（比如，存货控制），或者受控于一台小型计算机，如在检查或质量控制方面。无论这些控制方法如何，CAM的重要性在于它能产生两种信息流。BecausetheCAMsystemoverseesmanyaspectsofthemanufacturingprocess,changesdictatedbyinformationmonitoredformonesubtaskcanbetranslatedintocontroldataforsomeothersubtask.Forexample,inthemanufacturingtask,machining,inspection,andassemblyareallundercomputercontrol.Whenthecomputerrecognizesthatacomponentiscontinuallyoutoftolerance(basedoninformationfeedbackfromautomatedtestingequipment),itcanbeprogrammedtoeffectachangeintheactualmachiningprocesstocompensatefortheerror.Sincebothsubtasksbecomepartofthesameinformationloop,afeedbackcontrolsystemincludingmachiningandinspectionisestablished.因为CAM系统监控着制造过程的许多方面，由一具子任务检测到的信息所指示的变化，能转换为其他子任务的控制数据。例如，进行制造任务时，加工，检测，装配都受到计算机控制，当计算机检测到一个零部件不断地超差（根据来源于自动测试的反馈信息），他就能通过编程来实现实际加工过程的改变，以补偿误差，由于这两种子任务都是同一信息环的一部分，于是就建立了一种包含加工和检测的反馈控制系统。NCinComputer-AidedManufacturingAlthoughnumericallycontrolledmachinetoolsareessentialforthedevelopmentofoperat