數(shù)控技術(shù)數(shù)控編程外文翻譯@中英文翻譯@外文文獻(xiàn)翻譯

外文資料翻譯 1 原文： NC and CNC The History of NC and CNC Development Numerical Control (NC) is any machining process in which the operations are executed automatically in sequences as specified by the program that contains the information for the tool movements. The NC concept was proposed in the late 1940s by John Parsons of Traverse City, Michigan. Parsons recommended a method of automatic machine control that would guide a milling cutter to produce a thru-axis curve in order to generate smooth profiles on work pieces. In 1949, The U.S. Air Force awarded Parsons a contract to develop a new type of machine tool that would be able to speed up production methods. Parsons commissioned the Massachusetts Institute of Technology (M.I.T.) to develop a practical implementation of his concept. Scientists and engineers at M.I.T. built a control system for a two-axis milling machine that used a perforated paper tape as the input media. In a short period of time, all major machine tool manufacturers were producing some machines with NC, but it was not until the late 1970s that computer-based NC became widely used. NC matured as an automation technology when inexpensive and powerful microprocessors replaced hard-wire logic-making computer-based NC systems. When Numerical Control is performed under computer supervision, it is called Computer Numerical Control (CNC). Computers are the control units of CNC machines, they are built in or linked to the machines via communications channels. When a programmer input some information in the program by tape and so on, the computer calculates all necessary data to get the job done. On the first Numerically Controlled (NC) machines were controlled by tape, and because of that, the NC systems were known as tape-controlled machines. They were able to control a single operation entered into the machine by punched or magnetic tape. There was no possibility of editing the program on the machine. To change the program, a new tape had to be made. Todays systems have computers to control data； they are called Computer Numerically Controlled (CNC) machines. For both NC and CNC systems, work 外文資料翻譯 2 principles are the same. Only the way in which the execution is controlled is different. Normally, new systems are faster, more powerful, and more versatile The Applications of NC/CNC Since its introduction, NC technology has found many applications, including lathes and turning Centers, milling machines and machining centers , punches , electrical discharg machines(EDM) Flame cutters,grinders,and inspection equipment. the most complex CNC machine tools are the turning center,shown in Fig.4-1(Amodern turning center with a ten-station turret that accepts quick-chang tools.Each tool can be positioned in Seconds with the press of a button).And the machine center shown in Fig.4-2(Vertical machining center,the tool magazine is on the machine.the control panel on the right can be swiveled by the operator)and Fig.4-3(horizontal machining center,equipped with an automatic tool changer .tool magazines can store 200 ctting tools. When preparing a progam for a particular operation ,the prommer must select all cutting data using recommendations for conventional machining .this includes proper Selection of cutting speeds,feedrate,tools and tool geometry,and so on.when the programmer has chosen all of the necessary information properly,the operator loads the programme into the machine and presses a button to start the cutting crycle .the CNC machine moves automatically from one maching operation to another , changing the cutting tols and applying the coolent.in a surprisingly short time ,the workpiece is Machined according to the highest quality stangards. But that is not all.no matter how big the work series is,all of the parts will be almost identical in size and surface finishing. At this time of advanced technology,with its high demands for surface finishing and tolerances of components in,for example ,aerospace,nuclear,and medical equipment manufacturing,only CNC machines provide successful results. Numerical control (NC) is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols. The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular workpart or job. The instructions are provided by either of the two binary coded decimal systems: the Electronic Industries Association (EIA) code, or the American Standard Code for Information Interchange 外文資料翻譯 3 (ASCII). ASCII-coded machine control units will not accept . EIA coded instructions and vice versa. Increasingly, however, control units are being made to accept instructions in either code. 121Automation operation by NC is readily adaptable to the operation of all metalworking machines. Lathes, milling machines, drill presses, boring machines, grinding machines, turret punches, flame or wire-cutting and welding machines, and even pipe benders are available with numerical controls. Basic Components of NC A numerical control system consists of the following three basic components: (1) Program instructions (2) Machine control unit (3) Processing equipment The program instructions are the detailed step by step commands that direct the processing equipment. 31In its most common form, the commands refer to positions of a machine tool spindle with respect to the worktable on which the part is fixtured. More advanced instructions include selection of spindle speeds, cutting tools, and other functions. The machine control unit (MCU) consists of the electronics and control hardware that reads and interprets the program of instructions and convert it into mechanical actions of the machine tool or other processing equipment. The processing equipment is the component that performs metal process. In the most common example of numerical control, it is used to perform machining operations. The process-ing equipment consists of the worktable and spindle as well as the motors and controls needed to drive them. Types of NC There are two basic types of numerical control systems: point to point a nd contouring. Point to point control system, also called positioning, is simpler than contouring control system. Its primary purpose is to move a tool or workpiece from one programmed point to another. Usually the machine function, such as a drilling operation, is also activated at each point by command from the NC program. Point to point systems are suitable for hole machining operations such as drilling, 外文資料翻譯 4 countersinking, couterbofing, reaming, boring and tapping. Hole punching machines, spotwelding machines, and assembly machines also use point to point NC systems. Contouring system, also known as the continuous path system, positioning and cutting operations are both along controlled paths but at different velocities. Because the tool cuts as it travels along a prescribed path, accurate control and synchronization of velocities and movements are important. The contouring system is used on lathes, milling machines, grinders,incrementally, by one of several basic methods. There are a number of interpolation schemes that have been developed to deal with the various problems that are encountered in generating a smooth continuous path with a contouring type NC system. They include linear interpolation,circular interpolation, helical interpolation, parabolic interpolation and cubic interpolation. In all interpolations, the path controlled is that of the center of rotation of the tool. Compensation for different tools, different diameter tools, or tools wear during machining, can be made in the NC . Programming for NC A program for numerical control consists of a sequence of directions that causes an NC machine to carry out a certain operation, machining being the most commonly used process. Programming for NC may be done by an internal programming department, on the shop floor, or purchased from an outside source. Also, programming may be done manually or with computer assistance. The program contains instructions and commands. Geometric instructions pertain to relative movements between the tool and the workpiece. Processing instructions pertain to spindle speeds, feeds, tools, and so on. Travel instructions pertain to the type of interpolation and slow or rapid movements of the tool or worktable. Switching commands pertain to on/off position for coolant supplies, spindle rotation, direction of spindle rotation, tool changes, workpiece feeding, clamping, and so on. The first NC programming language was developed by MIT developmental work on NC programming systems in the late 1950s and called APT(Automatically Programmed Tools). DNC and CNC The development of numerical control was a significant achievement in batch 外文資料翻譯 5 and job shop manufacturing, from both a technological and a commercial viewpoint. There have been two enhancements and extensions of NC technology, including: (1) Direct numerical control (2) Computer numerical control Direct numerical control can be defined as a manufacturing system in which a number of machines are controlled by a computer through direct connection and in real time. The tape reader is omitted in DNC, thus relieving the system of its least reliable component. Instead of using the tape reader, the part program is transmitted to the machine tool directly from the computer memory. In principle, one computer can be used to control more than 100 separate machines. (One commercial DNC system during the 1970s boasted a control capability of up to 256 machine tools.) The DNC computer is designed to provide instructions to each machine tool on demand. When the machine needs control commands, they are communicated to it immediately. Since the introduction of DNC, there have been dramatic advances in computer technology. The physical size and cost of a digital computer has been significantly reduced at the same time that its computational capabilities have been substantially increased. In numerical control, the result of these advances has been that the large hard-wired MCUs of conventional NC have been replaced by control units based on the digital computer. Initially, minicomputers were utilized in the early 1970s. As further miniaturization occurred in computers, minicomputers were replaced by todays microcomputers. Computer numerical control is an NC system using dedicated microcomputer as the machine control unit. Because a digital computer is used in both CNC and DNC, it is appropriate to distinguish between the two types of system. There are three principal differences: 1) DNC computers distribute instructional data to, and collect data from, a large number of machines. CNC computers control only one machine, or a small number of machines. 2) DNC computers occupy a location that is typically remote from the machines under their control. CNC computer are located very near their machine tools. 外文資料翻譯 6 3) DNC software is developed not only to control individual pieces of production equipment, but also to serve as part of a management information system in the manufacturing sector of the firm. CNC software is developed to augment the capabilities of a particular machine Tool. 外文資料翻譯 7 譯文： 數(shù)控技術(shù) 數(shù)字控制與計(jì)算機(jī)數(shù)字控制的發(fā)展歷史 數(shù)字控制是按照含有機(jī)床 (刀具 )運(yùn)動(dòng)信息程序所指定的順序自動(dòng)執(zhí)行操作的加工過(guò)程。數(shù)控這一概念是由密歇根洲特拉華城的約翰 帕森于 20世紀(jì)四十年代后期提出的。為了在工件上加工光滑的輪廓，帕森提出了一種自動(dòng)的機(jī)床控制方式，它能夠引導(dǎo)銑床刀具加工出一種 “ 過(guò)軸曲線 ”。 1949 年，美國(guó)空軍與帕森簽署了合同，要求開(kāi)發(fā)一種能夠提高生產(chǎn)率的新型 機(jī)床。帕森委托麻省理工學(xué)院 (MIT)來(lái)開(kāi)發(fā)一種新概念機(jī)床，麻省理工學(xué)院的科學(xué)家和工程師研制出了一種用穿孔紙帶作為輸入媒介的二軸聯(lián)動(dòng)銑床控制系統(tǒng)。在較短時(shí)間內(nèi)，當(dāng)時(shí)所有主要的機(jī)床生產(chǎn)商都生產(chǎn)了一些數(shù)控機(jī)床，但直到20 世紀(jì)七十年代后期，基于計(jì)算機(jī)的數(shù)字控制才被得到廣泛的使用。只有價(jià)格低廉且功能強(qiáng)大的微處理芯片代替了計(jì)算機(jī)數(shù)控系統(tǒng)中的硬連線邏輯發(fā)生器后，NC才真正成為一門自動(dòng)化技術(shù)。 當(dāng)數(shù)控機(jī)床在計(jì)算機(jī)監(jiān)控下工作時(shí)，它就被稱為計(jì)算機(jī)數(shù)控機(jī)床 (CNC)。計(jì)算機(jī)是 CNC 機(jī)床的控制單元，它們內(nèi)嵌于數(shù)控機(jī)床或者通過(guò)通訊渠 道與數(shù)控機(jī)床聯(lián)接，當(dāng)程序員編程時(shí)，通過(guò)紙帶或磁盤(pán)將一些信息輸入，計(jì)算機(jī)將對(duì)一些必要的數(shù)據(jù)進(jìn)行計(jì)算的完成工作。 由于第一臺(tái)數(shù)控機(jī)床的數(shù)據(jù)是由紙帶控制的，因此數(shù)控系統(tǒng)被稱為紙帶控制機(jī)床。它們只能控制由輸入到機(jī)床內(nèi)的紙帶或磁帶所規(guī)定的單一操作，輸入到機(jī)床內(nèi)的程序是不能被編輯的，要改變程序必須重做新紙帶。 當(dāng)今的系統(tǒng)都由計(jì)算機(jī)來(lái)控制數(shù)據(jù)，因而稱之為計(jì)算機(jī)數(shù)控機(jī)床 (簡(jiǎn)稱 CNC機(jī)床 )。 NC和 CNC 系統(tǒng)兩者的工作原理一樣，僅僅控制執(zhí)行的方式不同。新型的數(shù)控系統(tǒng)通常速度更快、功率更大、功能更齊全。 數(shù)字控制與計(jì)算機(jī)數(shù)字控制 的應(yīng)用 數(shù)控技術(shù)自創(chuàng)立以來(lái)就得到了廣泛的應(yīng)用，包括車床和車削中心、銑床和加工中心、沖床、電火花 (EDM)加工機(jī)床、線切割機(jī)床、磨床以及測(cè)試檢測(cè)裝置等。最復(fù)雜的計(jì)算機(jī)數(shù)控機(jī)床是車削中心，圖 4 1 所示一個(gè)具有十轉(zhuǎn)位的刀架能進(jìn)行快速換刀的現(xiàn)代車削中心，立式加工中心如圖 4 2所示 (刀具庫(kù)在機(jī)床的左邊。右邊的控制面板可由操作者通過(guò)轉(zhuǎn)臂轉(zhuǎn)動(dòng) )，以及臥式加工中心，通過(guò)按下按鈕每把刀可在數(shù)秒鐘內(nèi)定位。如圖 4 3所示 (配有自動(dòng)換刀系統(tǒng)。刀具庫(kù)儲(chǔ)備有 200外文資料翻譯 8 把切削工具 )。 當(dāng)為某項(xiàng)操作編程時(shí)，程序員必須選擇傳統(tǒng)的加工切削數(shù)據(jù)推薦 值。這些切削數(shù)據(jù)包括切削速度、進(jìn)給率、刀具和刀具幾何形狀等。當(dāng)程序員正確選擇所有必要信息后，操作人員 將程序載入機(jī)床并按下按鈕，切削循環(huán)就開(kāi)始。 數(shù)控技術(shù)是一種利用程序?qū)崿F(xiàn)自動(dòng)控制的技術(shù)，加工制造設(shè)備采用數(shù)控技術(shù)后能由數(shù)字、字符和符號(hào)等進(jìn)行控制。這些數(shù)字、字符和符號(hào)等被編碼成按一定格式定義的指令程序用于一個(gè)特定的加工或工件，這些指令可以采用兩種二進(jìn)制編碼的數(shù)字系統(tǒng)中的任意一種進(jìn)行定義，這兩種二進(jìn)制編碼數(shù)字系統(tǒng)分別為電工協(xié)會(huì)代碼 (EIA)和美國(guó)標(biāo)準(zhǔn)信息交換 代碼 (ASCII)。一般來(lái)說(shuō)， ASCII 編碼的機(jī)床控制系 統(tǒng)不能接受 EIA 編碼的指令，反之亦然。當(dāng)然，這樣的問(wèn)題已經(jīng)逐漸得到解決。數(shù)控加工制造目前已經(jīng)廣泛地應(yīng)用于幾乎所有的金屬加工機(jī)床：車床，銑床，鉆床，鏜床，磨床，回轉(zhuǎn)沖床，電火化，線切割和焊接機(jī)床，甚至彎管機(jī)也采用數(shù)控加工技術(shù)。 數(shù)控技術(shù)的基本組成 一個(gè)數(shù)控系統(tǒng)主要由以下 3個(gè)部分組成： (1)程序指令 (2)加工 控制單元 (3)制造裝備 程序指令是由一條一條的詳細(xì)指令所組成，制造裝備按要求執(zhí)行這些指令。最常用的指令有：可以按要求使機(jī)床刀具主軸位于工作臺(tái)上的具體位置，工作臺(tái)是用于固定加工零件的，許 多更高級(jí)的指令還包括用于主軸速度的選擇、刀具速度的選擇及其他一些功能。 加工控制單元 (MCU)包括一些用于閱讀和解釋程序指令并將其轉(zhuǎn)換為機(jī)床刀具或其他制造裝備的機(jī)械動(dòng)作的電子和控制硬件。 制造裝備是一種進(jìn)行金屬加工的數(shù)控技術(shù)裝備，在常用的數(shù)控技術(shù)領(lǐng)域中，制造裝備用于進(jìn)行機(jī)械制造。制造裝備包括工作臺(tái)、主軸、電機(jī)及控制驅(qū)動(dòng)單元。 數(shù)控技術(shù)的類型 數(shù)控技術(shù)系統(tǒng)主要有兩種類型：點(diǎn)對(duì)點(diǎn)數(shù)控系統(tǒng)和輪廓線數(shù)控系統(tǒng)。 點(diǎn)對(duì)點(diǎn)數(shù)控系統(tǒng)也稱為位置數(shù)控系統(tǒng)，比輪廓線數(shù)控系統(tǒng)簡(jiǎn)單，其主要的原理是移動(dòng)刀具或工件從一個(gè)程序控制 點(diǎn)到另一一個(gè)控制點(diǎn)，通常像鉆床這樣的加工功能，每個(gè)點(diǎn)幫司以通過(guò) NC程序中的指令進(jìn)行控制。點(diǎn)對(duì)點(diǎn)數(shù)控系統(tǒng)適用于外文資料翻譯 9 像鉆孔、沉孔加工、沉孔鏜孔、鉸孔和攻絲等。其他沖孔機(jī)床、點(diǎn)焊機(jī)和裝配機(jī)床等也都采用點(diǎn)對(duì)點(diǎn)數(shù)控系統(tǒng)。 輪廓線數(shù)控系統(tǒng)也稱為輪廓線路徑數(shù)控系統(tǒng)，定位和切割操作都是