【正文】 僅僅小部分的零件種類可隨時加工，而更少的工件需要完成于它相同的操作。事實上它的利用水平很低，機(jī)床刀具昂貴會導(dǎo)致加工頻繁時的“頸瓶”現(xiàn)象，于是進(jìn)一步限制了整個操作。 13 世紀(jì) 70 年代初中葉，是機(jī)床刀具控制器變革時期，這個時期， CNC 成為了一個現(xiàn)實。新的控制器的產(chǎn)生便使公司可通過改變程序改變了一個工件外形。微型技術(shù)的發(fā)展，可成功的加工一批或一個 2 全件。當(dāng)兩個相關(guān)的因素存在后，在一個生產(chǎn)環(huán)境中，讓 CNC 實現(xiàn)靈活且 輕松的編程的夢想變成為現(xiàn)實。這些現(xiàn)實是： 集成電路的發(fā)展，它減少了電路的尺寸，使得維護(hù)便利且有利于設(shè)計的標(biāo)準(zhǔn)化。 計算機(jī)的體積減小，從而它的生產(chǎn)費(fèi)用也極大的降低。價格便宜，性能穩(wěn)定等多種優(yōu)點(diǎn)使得今天的 CNC 安裝在機(jī)床刀具上。隨著它的不斷發(fā)展成熟，使在高級的 CNC 系統(tǒng)上可安上人工智能。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。 由資金耗費(fèi)項目上的考慮，就 CNC 機(jī)床刀具而言，為了明確新計劃是否必要或證明在短期內(nèi)實現(xiàn)資金回收，一個公司必須進(jìn)行可行性分析。這些想 法及重要的決定將會成為考慮 CNC 系統(tǒng)經(jīng)濟(jì)性調(diào)整問題的主題。 英文原文 ADVANCED MACHINING PROCESSES As the hardware of an advanced technology bees more plex, new and visionary approaches to the processing of materials into useful products e into mon use. This has been the trend in machining processes in recent years.. Advanced methods of machine control as well as pletely different methods of shaping materials have permitted the mechanical designer to proceed in directions that would have been totally impossible only a few years ago. Parallel development in other technologies such as electronics and puters have made available to the machine tool designer methods and processes that can permit a machine tool to far exceed the capabilities of the most experienced machinist. In this section we will look at CNC machining using chipmaking cutting tools. CNC controllers are used to drive and control a great variety of machines and mechanisms, Some examples would be routers in wood working。 lasers, plasmaarc, flame cutting, and waterjets for cutting of steel plate。 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 controls are rapidly and constantly taking place. The exciting part of this evolution in machine controls is that programming beeseasier with each new advanced in this technology. Advantages of Numerical Control A manually operated machine tool may have the same physical characteristics as a CNC machine, such as size and horsepower. The principles of metal removal are the same. The big gain es from the puter controlling the machining axes movements. CNCcontrolled machine tools can be as simple as a 2axis drilling machining center (Figure O1). With a dual spindle machining center, the low RPM, high horsepower spindle gives high metal removal rates. The high RPM spindle allows the efficient use of high cutting speed tools such as diamonds and small diameter cutters (Figure O2). The cutting tools that remove materials are standard tools such as milling cutters, drills, boring tools, or lathe tools depending on the type of machine used. Cutting speeds and feeds need to be correct as in any other machining operation. The greatest advantage in CNC machining es from the unerring and rapid positioning movements possible. A CNC machine does dot stop at the end of a cut to plan its next move。 it does not get fatigued。 it is capable of uninterrupted machining error free, hour after hour. A machine tool is productive only while it is making chips. Since the chipmaking process is controlled by the proper feeds and speeds, time savings can be achieved by faster rapid feed rates. Rapid feeds have increased from 60 to 200 to 400 and are now often approaching 1000 inches per minute (IPM). These high feed rates can pose a safety hazard to anyone within the working envelope of the machine tool. Complex contoured shapes were extremely difficult to product prior to CNC machining .CNC has made the machining of these shapes economically feasible. Design changes on a part are relatively easy to make by changing the program that directs the machine tool. A CNC machine produces parts with high dimensional accuracy and close tolerances without taking extra time or special precautions, CNC machines generally need less plex workholding fixtures, which saves time by getting the parts machined sooner. Once a program is ready and production parts, each part will take exactly the same amount of time as the previous one. This repeatability allows for a very precise control of production costs. Another advantage of CNC machining is the elimi nation of large inventories。 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。 conversational input is also called userfriendly or prompted input. Later in