【正文】 re a range of ponents using a wide variety of machining processes at a single setup, without transfer of workpieces to other variety machine tools. A machining center differed conceptually in its design from that of a milling machine, In that the cutting tools could be changed automatically by the transfer machanism, or selector, from the magazine to spindle, or vice this ductively and the automatic tool changing feature enabled the machining center to productively and efficiently machine a range of ponents, by replacing old tools for new, or reselecting the next cutter whilst the current machining process is in cycle. In the mid 1960s,a UK pany, Molins, introduced their unique System 24 which was meant represent the ability of a system to machine for 24 hours per day. It could be thought of as a machining plex which allowed a series of NC single purpose machine tools to be linked by a puterized conveyor system. This conveyor allowed the work pieces to be palletized and then directed to as machine tool as necessary. This was an early, but admirable, attempt at a form of Flexible manufacturing System concept, but was unfortunately doomed to failure. Its principal weakness was that only a small proportion of ponent varieties could be machine at any instant and that even fewer work pieces required the same operations to be performed on them. These factors meant that the utilization level was low, coupled to the fact that the machine tools were expensive and allowed frequent production bottlenecks of workinprogress to arise, which further slowed down the whole operation. The early to mid1970s was a time of revolutionary in the area of machine tool controller development, when the term puterized numerical control (CNC) became a reality. This new breed of controllers gave a pany the ability to change work piece geometries, together with programs, easily with the minimum of development and lead time, allowing it to be economically viable to machine small batches, or even oneoff successfully. The dream of allowing a puterized numerical controller the flexibility and ease of program editing in a production environment became a reality when two ralated factors were:the development of integrated circuits, which reduces electronics circuit size, giving better maintenance and allowing more standardization of desing。s contribution to this numerical control development. A major problem occurred just after the Second World War, in that progress in all areas of military and mercial development had been so rapid that the levels of automation and accuracy required by the modern industrialized world could not be attained from the lab our intensive machines in use at that time. The question was how to overe the disadvantages of conventional plant and current manni ng levels. It is generally acknowledged that the earliest work into numerical control was the study missioned in 1947 by the US government. The study39。 parts can be machined as needs .In conventional production often a great number of parts must be made at the same time to be cost effective. With CNC even one piece can be machined economically .In many instances, a CNC machine can perform in one setup the same operations that would require several conventional machines. With modern CNC machine tools a trained machinist can program and product even a single part economically .CNC machine tools are used in small and large machining facilities and range in size from tabletop models to huge machining centers. In a facility with many CNC tools, programming is usually done by CNC programmers away from the CNC tools. The machine control unit (MCU) on the machine is then used mostly for small program changes or corrections. Manufacturing with CNC tools usually requires three categories of persons. The first is the programmer, who is responsible for developing machineready code. The next person involved is the setup person, who loads the raw stork into the MCU, checks that the correct tools are loaded, and makes the first part. The third person is the machine and unloads the finished parts. In a small pany, one person is expected to perform all three of these tasks. CNC controls are generally divided into two basic categories. One uses a ward address format with coded inputs such as G and M codes. The other users a conversational input。這些年來，刀具制作者已經(jīng)制作了多種多樣的刀具可用在 CNC 系統(tǒng)上，其中的一部分在第 3 冊中將被討論。 13 世紀(jì) 70 年代初中葉，是機(jī)床刀具控制器變革時(shí)期，這個(gè)時(shí)期， CNC 成為了一個(gè)現(xiàn)實(shí)。一個(gè)加工中心不同于一個(gè)磨床，相互要在于它能利用轉(zhuǎn)移裝置和分離器自動(dòng)的把切削刀具從刀具庫中轉(zhuǎn)移到主軸上。較簡單的點(diǎn)與點(diǎn)機(jī)床比復(fù)雜的連續(xù)路徑的同類產(chǎn)品便宜一些，并在用于需要精確定位的加工中。在 1949— 1951 期間，他們聯(lián)合發(fā)明了一種可適合多種刀具的第一個(gè)數(shù)控系統(tǒng)。 直到你理解它們的功能和動(dòng)作方可操作這臺機(jī)床。 CAD/CAM 相互影響的方向的不斷探索和發(fā)展將會改變他們的工作方式。所需的總時(shí)間的確定可用 來估計(jì)生產(chǎn)費(fèi)用。這和詳細(xì)指明加工這個(gè)部件 的 CNC 機(jī)床一樣容易。某部件的 孔的加工就是一個(gè)例子。從已準(zhǔn)備好 的 JOBPLAN 中選好機(jī)床后，切削加工的參數(shù)就被編入?，F(xiàn)在我們測試 CAM 系統(tǒng)怎樣工作。這就勝任于粗選中最佳馬力的選擇。舉例如選擇最佳的切削工具來完成零件圖上所標(biāo)的公差和表面光潔度。每個(gè)制造商在不斷地提高和更新其 CNC 控制。有了 CNC 即使一件也能夠被經(jīng)濟(jì)地加工。 CNC 使這些形狀的加工制造在經(jīng)濟(jì)上是可行的。兩軸的加工機(jī)床，其特點(diǎn)是低轉(zhuǎn)速、高馬力軸有高進(jìn)給率，高轉(zhuǎn)速軸允許高效的高速切削刀具如鉆石和小直徑的刀具的使用（如圖 O2）。 在這個(gè)部分我們來看數(shù)控機(jī)床切削使用的工具。這已經(jīng)成為近幾年機(jī)床加工的發(fā)展趨勢。在機(jī)床控制發(fā)展中的精彩部分是在每個(gè)先進(jìn)技術(shù)上的使用變得很容易了。 當(dāng)切削過程被適當(dāng)?shù)倪M(jìn)給量和切削速度控制時(shí)，時(shí)間的節(jié)約可以通過快速的進(jìn)給率來完成。這個(gè)一致性允許 很精確地控制加工成本。許多CNC 代碼語句可被不同的控制器識別。 CNC 程序員必須對這個(gè)即將寫入程序的CNC 機(jī)床的能力和局限有一個(gè)完全的了解。新刀具的信息來自手冊或刀具制造商的刀具之資料。程序被用來計(jì)算磨床每次進(jìn)的給量，特別是在微量的光潔度加工中。首先還是工藝卡的建立。 在程序運(yùn)行的任意時(shí)刻，命令 SHOWPATH 會顯示當(dāng)前的刀具軌跡，也會顯示刀具在實(shí)際加工時(shí)的使用順序。一個(gè)CAM 系統(tǒng)可讓程序員從不同的角度觀察圖形，比如說從頂部、正面、側(cè)面或立體圖。當(dāng)代碼發(fā)生器完成時(shí)，加工的計(jì)劃時(shí)間就確定了。程序員仍需準(zhǔn)備一個(gè)工藝卡，含有所用需要的刀具。啟動(dòng)機(jī)床之前，確定工作裝置和工件是否安全的固定了 。通常認(rèn)為，關(guān)于數(shù)控的研究是 1949 年美國政府的授權(quán)。幾年后，在 USA 與歐洲開始了更深遠(yuǎn)的研究。 早期的 NC 機(jī)床，主要的在磨床基礎(chǔ)發(fā)展起來的，控制的概念主要用于形成，打孔，磨削以及后來的大量的另外的機(jī)床刀具。這是早期情形，是值得欽佩的。 計(jì)算機(jī)的體積減小，從而它的生產(chǎn)費(fèi)用也極大的降低。 and controlling of robots in manufacturing and assembly. This section is only an overview and cannot take the place of a programming manual for a specific machine tool. Because of the tremendous growth in numbers and capability of puters ,changes in machine contr