数控专业外文翻译5abpd.doc

宁夏大学机械工程学院2011届毕业设计numerical controlnumerical control is a form of programmable automation in which the processing equipment is controlled by means of numbers，letters，and other symbolsthe numbers，letters，and symbols are coded in an appropriate format to define a program of instructions for a particular work part or jobwhen the job changes，the program of instructions is changedthe capability to change the program is what makes nc suitable for low-and medium-volume productionit is much easier to write programs than to make major alterations of the processing equipmentnumber control lather main use to carry on a car to pare towards revolving body spare parts, the tang pare, drill to pare, the jiao pare, offend silk etc. process of work preface. general ability auto inside completion outside cylinder noodles, conic surface, surface of sphere, cylinder thread, slot and carry noodles etc. the slice of work preface pare to process.the host is the topic that the number control lather and include a tool machine body, sign pillar, principal axis and enter etc. is to the organization machine parts. number control equip, is number control tool machine of core, include hardware and correspond of software, used for an importation numeral turn of spare parts procedure, and completion importation information of saving, the transformation of data, put to repair operation and realization various control function. drive to equip, he is number control the drive of organization of the tool machine performance parts, include a principal axis to drive unit and enter to the unit, principal axis electrical engineering and enter etc. to electrical engineering. he under the control that number control to equip pass electricity or electricity liquid servo system realization principal axis with enters give drive. when several enter to give allied move, can completion fixed position, straight line, process of flat surface curve and space curve. assistance equips the index number control tool machine of some necessity of kit parts, in order to assurance number control tool machine of circulate, such as cool off, row scraps, lubricate, illuminate, monitor etc. it include a liquid to press friendly move equip, row scraps equip, exchange work set, number control to turn taiwan and number control cent degree head. plait distance and other subsidiary equipments, can use to carry on the procedure of spare parts to draw up outside machine, saving.modern number control lather to all have x, z two stalk of allied move function, knife position and point of a knife arc radius of compensate function, and process fix circulation function.the number control the structure of lather1. the number control a lather brief introductionthe number control constitute of lather: number control system, bed body, principal axis and enter to the system, turn round a knife, operation front-panel and assistance system etc. (1) the economy number control lather: adoption step enter electric motor and list slice machine to common the car of the lather pare into to the system carry on reformation behind formation of the simple number control lather. the cost is lower, automation degree and function be all more bad, the car pare to process accuracy also not high, be applicable to request not high of turn round type spare parts of the car pare to process.the economy number control lather(2) common number control lather: pare to process a request to carry on the structure according to the car specialized design, equipment in general use number control system but formation of number control lather. number control system function strong, automation degree with process accuracy also more ago, be applicable to general turn round type spare parts of the car pare to process. this kind of number control lather can control 2 sit a mark stalk in the meantime, namely x stalk and z stalk.common number control lather(3)the turning center: at common number control the foundation of lather up, increment c stalk and motive head, more high class of the tool machine still take a knife database, can control x, z and c 3 sit mark stalk, allied move control stalk can be(x, z),(x, c) or(z, c).because increment c stalk and xian pare a motive head, this kind of number control process of lather function consumedly strengthen, in addition to carry on general the car pare, also can carry on path to pare with stalk toward the xian, the curved face xian pare, the center line dont turn round in the spare parts center of bore and path pare toward the drill of bore etc. process.2. the liquid press card dish and liquid to press a tailthe liquid press card dish is number control a car to pare to process clip tight work piece of importance enclosure, rightness general turn round type spare parts can adoption common the liquid press card dish; to the spare parts be clip hold the part isnt the spare parts of cylinder form, demand adoption appropriation card dish; with the stick anticipate direct process spare parts demand adoption spring coil card dish.to stalk to the size and the path is to the specific value bigger spare parts of size, demand adoption install press a tail in the liquid up of live top carry on prop up to the spare parts end tip, then can assurance carry on to the spare parts exactitude of process. the tail has a common liquid to press tail and programmable liquid to press a tail.3. the number control the knife of lathernumber control lather can equipment two kinds of knife:(1) appropriation knife from lather produce manufacturer oneself development, haft for use is also appropriation of. this kind of the advantage be that the manufacturing cost is low, but lack in general use.(2)in general use knife according to certain in general use standard(like vdi, germany engineers association) but produce of knife, number control lather production manufacturer can according to number control the function of lather request to carry on a choice allocation.in general use knife4. the milling a motive headnumber control lather knife top to install xian after pare the motive head can consumedly expand number to control process of lather ability. such as :make use of the xian pare a motive head to carry on stalk to drill a hole to pare stalk toward the slot with xian.the nc system consists of the following components：data input，the tape reader with the control unit，feedback devices，and the metalcutting machine tool or other type of nc equipmentdata input，also called “mantocontrol link”，may be provided to the machine tool manually，or entirely by automatic meansmanual methods when used as the sole source of input data are restricted to a relatively small number of inputsexamples of manually operated devices are keyboard dials，pushbuttons，switches，or thumbwheel selectorsthese are located on a console near the machinedials ale analog devices usually connected to a syn-chro-type resolver or potentiometerin most cases，pushbuttons，switches，and other similar types of selectors aye digital input devicesmanual input requires that the operator set the controls for each operationit is a slow and tedious process and is seldom justified except in elementary machining applications or in special casesin practically all cases，information is automatically supplied to the control unit and the machine tool by cards，punched tapes，or by magnetic tapeeightchannel punched paper tape is the most commonly used form of data input for conventional nc systemsthe coded instructions on the tape consist of sections of punched holes called blockseach block represents a machine function，a machining operation，or a combination of the twothe entire nc program on a tape is made up of an accumulation of these successive data blocksprograms resulting in long tapes all wound on reels like motion-picture filmprograms on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a looponce installed，the tape is used again and again without further handlingin this case，the operator simply loads and unloads the partspunched tapes ale prepared on type writers with special tapepunching attachments or in tape punching units connected directly to a computer systemtape production is rarely error-freeerrors may be initially caused by the part programmer，in card punching or compilation，or as a result of physical damage to the tape during handling，etcseveral trial runs are often necessary to remove all errors and produce an acceptable working tapewhile the data on the tape is fed automatically，the actual programming steps ale done manuallybefore the coded tape may be prepared，the programmer，often working with a planner or a process engineer, must select the appropriate nc machine tool，determine the kind of material to be machined，calculate the speeds and feeds，and decide upon the type of tooling needed. the dimensions on the part print are closely examined to determine a suitable zero reference point from which to start the programa program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specificationsthe control unit receives and stores all coded data until a complete block of information has been accumulatedit then interprets the coded instruction and directs the machine tool through the required motionsthe function of the control unit may be better understood by comparing it to the action of a dial telephone，where，as each digit is dialed，it is storedwhen the entire number has been dialed，the equipment becomes activated and the call is completedsilicon photo diodes，located in the tape reader head on the control unit，detect light as it passes through the holes in the moving tapethe light beams are converted to electrical energy，which is amplified to further strengthen the signalthe signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drivessome photoelectric devices are capable of reading at rates up to 1000 characters per secondhigh reading rates are necessary to maintain continuous machinetool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operationsthe reading device must be capable of reading data blocks at a rate faster than the control system can process the dataa feedback device is a safeguard used on some nc installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine toolan nc machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop systempositioning control is accomplished by a sensor which，during the actual operation，records the position of the slides and relays this information back to the control unitsignals thus received ale compared to input signals on the tape，and any discrepancy between them is automatically rectifiedin an alternative system，called an openloop system，the machine is positioned solely by stepping motor drives in response to commands by a controllersthere are three basic types of nc motions, as follows:point-to-point or positional control in point-to-point control the machine tool elements (tools, table, etc.) are moved to programmed locations and the machining operations performed after the motions are completed. the path or speed of movement between locations is unimportant; only the coordinates of the end points of the motions are accurately controlled. this type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece. straight-line or linear control straight-line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining. it is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined. this type of controlled motion is often referred to as linear control or a half-axis of control. machines with this form of control are also capable of point-to-point control.continuous path or contouring control in continuous path control the motions of two or more of the machine axes are controlled simultaneously, so that the position and velocity of the can be tool are changed continuously. in this way curves and surfaces can be machined at a controlled feed rate. it is the function of the interpolator in the controller to determine the increments of the individual controlled axes of the machines necessary to produce the desired motion. this type of control is referred to as continuous control or a full axis of control.some terminology concerning controlled motions for nc machines has been introduced. for example, some machines are referred to as four-or five-or even six-axis machines. for a vertical milling machine three axes of control are fairly obvious, these being the usual x, y, z coordinate directions. a fourth or fifth axis of control would imply some form of rotary table to index the work piece or possibly to provide angular motion of the work head. thus, in nc terminology an axis of control is any controlled motion of the machine elements (spindles, tables, etc). a further complication is use of the term half-axis of control; for example, many milling machines are referred to as 2.5-axis machine. this means that continuous control is possible for two motions (axes) and only linear control is possible for the third axis. applied to vertical milling machines, 2.5axis control means contouring in the x, y plane and linear motion only in the z direction. with these machines three-dimensional objects have to be machined with water lines around the surface at different heights. with an alternative terminology the same machine could be called a 2cl machine (c for continuous, l for linear control). thus, a milling machine with continuous control in the x, y, z directions could be termed be a three-axis machine or a 3c machine, similarly, lathes is usually two axis or 2c machines. the degree of work precision depends almost entirely upon the accuracy of the lead screw and the rigidity of the machine structurewith this systemthere is no self-correcting action or feedback of information to the control unitin the event of an unexpected malfunction，the control unit continues to put out pulses of electrical currentif，for example，the table on a nc milling machine were suddenly to become overloaded，no response would be sent back to the controllerbecause stepping motors are not sensitive to load variations，many nc systems are designed to permit the motors to stall when the resisting torque exceeds the motor torqueother systems are in use，however，which in spite of the possibility of damage to the machine structure or to the mechanical system，ale designed with special hightorque stepping motorsin this case，the motors have sufficient capacity to “overpower” the system in the event of almost any contingency数 控数控是可编程自动化技术的一种形式，通过数字、字母和其他符号来控制加工设备。数字、字母和符号用适当的格式编码为一个特定工件定义指令程序。当工件改变时，指令程序就改变。这种改变程序的能力使数控适合于中、小批量生产，写一段新程序远比对加工设备做大的改动容易得多。数控车床主要用来对旋转体零件进行车削、镗削、钻削、铰削、攻丝等工序的加工。一般能自动完成内外圆柱面、圆锥面、球面、圆柱螺纹、槽及端面等工序的切削加工。主机是数控车床的主题，包括机床身、立柱、主轴、进给机构等机械部件。数控装置，是数控机床的核心，包括硬件以及相应的软件，用于输入数字化的零件程序，并完成输入信息的存储、数据的变换、插补运算以及实现各种控制功能。驱动装置，他是数控机床执行机构的驱动部件，包括主轴驱动单元、进给单元、主轴电机及进给电机等。他在数控装置的控制下通过电气或电液伺服系统实现主轴和进给驱动。当几个进给联动时，可以完成定位、直线、平面曲线和空间曲线的加工。辅助装置，指数控机床的一些必要的配套部件，用以保证数控机床的运行，如冷却、排屑、润滑、照明、监测等。它包括液压和气动装置、排屑装置、交换工作台、数控转台和数控分度头。编程及其他附属设备，可用来在机外进行零件的程序编制、存储等。现代数控车床都具有x、z两轴的联动功能、刀具位置和刀尖圆弧半径的补偿功能、以及加工固定循环功能。数控车床的结构1.数控车床简介数控车床的组成：数控系统、床身、主轴、进给系统、回转刀架、操作面板和辅助系统等。(1)经济型数控车床：采用步进电动机和单片机对普通车床的车削进给系统进行改造后形成的简易型数控车床。成本较低，自动化程度和功能都比较差，车削加工精度也不高，适用于要求不高的回转类零件的车削加工。经济型数控车床(2)普通数控车床：根据车削加工要求在结构上进行专门设计，配备通用数控系统而形成的数控车床。数控系统功能强，自动化程度和加工精度也比较高，适用于一般回转类零件的车削加工。这种数控车床可同时控制两个坐标轴，即x轴和z轴。普通数控车床(3)车削加工中心：在普通数控车床的基础上，增加了c轴和动力头，更高级的机床还带有刀库，可控制x、z和c三个坐标轴，联动控制轴可以是(x、z)、(x、c)或(z、c)。由于增加了c轴和铣削动力头，这种数控车床的加工功能大大增强，除可以进行一般车削外，还可以进行径向和轴向铣削、曲面铣削、中心线不在零件回转中心的孔和径向孔的钻削等加工。2.液压卡盘和液压尾架液压卡盘是数控车削加工时夹紧工件的重要附件，对一般回转类零件可采用普通液压卡盘；对零件被夹持部位不是圆柱形的零件，则需要采用专用卡盘；用棒料直接加工零件时需要采用弹簧卡盘。对轴向尺寸和径向尺寸的比值较大的零件，需要采用安装在液压尾架上的活顶尖对零件尾端进行支撑，才能保证对零件进行正确的加工。尾架有普通液压尾架和可编程液压尾架。3.数控车床的刀架数控车床可以配备两种刀架：(1)专用刀架 由车床生产厂商自己开发，所使用的刀柄也是专用的。这种刀架的优点是制造成本低，但缺乏通用性。(2)通用刀架 根据一定的通用标准(如vdi，德国工程师协会)而生产的刀架，数控车床生产厂商可以根据数控车床的功能要求进行选择配置。4.铣削动力头数控车床刀架上安装铣削动力头后可以大大扩展