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Unit1IntroductiontoComputerNumericalControlManufacturing第1单元计算机数控加工简介ReadingTargetAfterreadingthisunit,youshouldbeabletoexplainwhatcomputernumericalcontrol(CNC)isandwhatbasiccomponentscompriseCNCsystems.Text1.1DefinitionofComputerNumericalControlanditscomponentsAcomputernumericalcontrol(CNC)machineisanNCmachinewiththeaddedfeatureofanon-boardcomputer.Theon-boardcomputerisoftenreferredtoasthemachinecontrolunitorMCU.1.1CNC的定义及其系统组成计算机数控机床就是在NC机床的基础上附加一个内置式计算机,这种内置式计算机通常被称为机床控制单元或MCU。NC机床的控制单元通常由硬件构成,也就是说机床的功能是由控制器内置的物理电子元件控制的。TextControlunitsforNCmachinesareusuallyhardwired.Thismeansthatamachinefunctionsarecontrolledbythephysicalelectronicelementsthatarebuiltintothecontroller.Simplyput,numericalcontrolisamethodofautomaticallyoperatingamanufacturingmachinebasedonacodeofletters,numbers,andspecialcharacters.NC机床的控制单元通常由硬件构成,也就是说机床的功能是由控制器内置的物理电子元件控制的。简单地说,数字控制是基于代码自动操作制造类机床的一种方法,这些代码由字母、数字和特殊字符组成。Acompletesetofcodedinstructionsforexecutinganoperationiscalledaprogram.SuchprogramsarestoredinRAMortherandom-accessmemoryportionofthecomputer.Theycanbeplayedback,edited,andprocessedbythecontrol.Thus,themachinefunctionsareencodedintothecomputeratthetimeofmanufacture.所谓的程序就是用于执行某一操作的一整套代码表示的指令,而这些程序是存放在计算机的随机存储器中的,控制器可以对它们进行重新调用,编写以及处理等操作。因此,我们可以通过对计算机进行编码从而在加工时实现机床操作的各种功能。TextThecomponentsfoundinmanyCNCsystemsareshowninFigure1-1.Machinecontrolunit:generates,storesandprocessesCNCprograms.Themachinecontrolunitalsocontainsthemachinemotioncontrollerintheformofanexecutivesoftwareprogram.NCmachine:respondstoprogrammedsignalsfromthemachinecontrolunitandmanufacturesthepart.CNC系统中常见的组成部分如图1-1所示。机床控制单元:生成、存储和处理CNC程序。机床控制单元还包括机床运动控制器,该控制器是一个可执行的软件程序。NC机床:响应来自机床控制单元的程序信号并对零件进行加工。TextTextFig1-1ComponentsofmodernCNCsystem现代CNC系统的组成1.2TypesofCNCequipmentMachiningcentersarethelatestdevelopmentinCNCtechnology.Thesesystemscomeequippedwithautomatictoolchangerswiththecapabilityofchangingupto90ormoretools.Manyarealsofittedwiththemovablerectangularworktablescalledpallets.Thepalletsareusedtoautomaticallyloadandunloadworkpieces.1.2CNC设备的类型加工中心在CNC技术中属于最前沿的。它们装有自动换刀装置,可换刀具数高达90把甚至更多。许多加工中心还装有可移动的长方形工作台,即托盘系统。这种托盘系统用来自动装卸工件。TextAtasinglesetupmachiningcenterscanperformsuchoperationsasmilling,drilling,tapping,boring,andsoon.Additionallybyutilizingindexingheads,somecentersarecapableofexecutingthesetasksonmanydifferentfacesofapartandatspecifiedangles.Machiningcenterssaveproductiontimeandcostbyreducingtheneedformovingapartfromonemachinetoanother.加工中心只需一次装卡就可以完成铣、钻、攻丝、镗等多种加工操作。此外,一些加工中心利用分度头可以对零件不同的面和特定的角度进行加工。通过减少零件在机床间转移,加工中心能够节省生产时间与成本。TextTextTurningcenterswithincreasedcapacitytoolchangersarealsomakingstrongappearanceinmodernproductionshops.TheseCNCmachinesarecapableofexecutingmanydifferenttypesoflathecuttingoperationssimultaneouslyonrotatingpart.具有大容量刀库的车削中心在现代制造厂中占据着显著位置。这些CNC机床能对旋转的工件同时进行多种车削加工。TextInadditiontomachiningcentersandturningcenters,CNCtechnologyhasalsobeenappliedtomanyothertypesofmanufacturingequipment.Amongthesearewireelectricaldischargemachines(wireEDM)andlasercuttingmachines.除加工中心和车削中心之外,CNC技术还被广泛用于其他许多类型的设备,其中包括线切割机床和激光切割机。TextWireEDMmachinesutilizeaverythinwireasanelectrode.Thewireisstretchedbetweentworollersandcutsthepartlikeaband-saw.Materialisremovedbytheerosioncausedbyasparkthatmoveshorizontallywiththewire.CNCisusedtocontrolhorizontaltablemovements.线切割机是用一根很细的切割丝做电极。切割丝在两个导轮之间拉紧,像带锯一样切割工件。切割丝水平移动所产生的电火花会将材料腐蚀掉,而CNC就是用来控制水平工作台的移动。TextLasercuttingCNCmachinesutilizeanintensebeamoffocusedlaserlighttocutthepart.Materialunderthelaserbeamundergoesarapidriseintemperatureandisvaporized.Ifthebeampowerishighenough,itwillpenetratethroughthematerial.Becausenomechanicalcuttingforcesareinvolved,laserscutpartswithaminimumofdistortion,theyhavebeenveryeffectiveinmachiningslotsanddrillingholes.激光切割CNC机床能利用一束强烈的聚焦光线来切割工件。材料在光线的照射下温度会骤然上升并汽化。若光束能量足够高就会将材料穿透。由于没有机械切削力,所以激光加工的工件变形非常小,激光切割机对加工窄槽和钻孔非常有效。KeyTermsComputerNumericalControl计算机数字控制MCUMachinecontrolunit机床控制单元electronicelement电子元件controller控制器RAMrandom-accessmemory随机存储器machiningcenter加工中心pallet托盘ATCautomatictoolchanger自动换刀装置workpiece\workpiece工件KeyTermsmilling铣削drilling钻孔tapping攻丝boring镗孔indexinghead分度头turningcenter车削中心lathe车床electricaldischargemachine电火花加工机床wireEDMwireelectricaldischargemachine线切割电火花加工机床KeyTermslasercuttingmachine激光切割机床machining机械加工slot窄槽
本文标题:数控专业英语
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