附錄 A英文翻譯 原文 : Abstract: This paper presents a method of machining inner cavities of precision aerostatic bearings by NC synchro-rotary EDM. This method can easily machine the precision aerostatic bearing to give symmetry of 10um and the surface roughness of Ra0.4um. This paper analyses the principle and the condition of the technique, and introduces the machining apparatus and control system. Keywords: Aerostatic bearing Syncro-rotary. 1. Introduction Air bearing is developed with the emerging of high technology. It employs gas as lubricate so it shows extremely low friction and wear, no heat ph rotary precision, etc. It hasroducing, the hig been widely used in aerospace, precision machine tool, medical instrument and electronics industries (1,2). The precision aerostatic bearing is one of air bearing with the highest rotary precision. Its special cavities are shown in Fig.1 Fig.1 the inner cavities of air bearing It is used in measuring appliances and precision machine tools. The symmetry of aerostatic bearing cavities is high, so it is difficult to be machined, specially taper or sphere cavities. In order to obtain high symmetry, general methods must employ special fixture with high precision index head. The methods show high machining costs and complicated operation for small serial production. On the basis of this condition, the condition, the synchronous rotary electrical discharge machining (SREMD) with NC system is presented. This method can easily machine the precision aerostatic bearing cavities with low machining costs. 2. The principle and advantages of SREDM The principle of SREDM is shown in Fig.2. Fig.2 the principle of SREDM During machining, the workpiece is a negative pole and the tool is a positive pole. The tool electrode turns at the speed twice of that of workpiece. At the same time, the slow feed in the vertical direction of electrode spindle is added. As the workpiece turns one cycle, the same point of facing two cavities. Because if the tool wear in one cycle is negligible, it can be considered that the two cavities are symmetrically machined by the just same point of the tool. The high symmetry of cavities is machined with low machining costs. The throttling slots in bearing can also be machined by the same way. The condition of SREDM is: D=2d 21 Where: D- the diameter of the cavity, d -the diameter of the tool electrode, 1 - the angular velocity of the workpiece, 2 - the angular velocity of the tool electrode. The advantage of the technology are: (1) This method can machine conduct materials with any hardness, so the bearing can be quenched before being machined and the effect of quenching is eliminated. (2) The high stiffness machine tool is not necessary, because of no large cutting force in machining. (3) The simple shaping principle makes the process omit the fixture with high precision index head. (4) This method supplies the high symmetry precision. (5) The low roughness is obtained by this method. (6) By programming, this method can machine other complex surface of inner cavity. 3. Machining the cavity on WEDM machine tool by SREDM The SREDM can be achieved on a WEDM machine tool with adding two accessories, WEDM machine tool. The refitted machine equipment is showed in figure 3. Accessory 1 whose shaft is driven by stepping motor directly is fixed on the body of the machine tool. The electrode is fixed on the shaft. Accessory 2 whose shaft is directly driven by anther stepping motor is fixed on the worktable of the machine tool. The workpiece is fixed on the shaft. The two shafts are on the same horizontal plane and parallel with the X direction of the worktable. The tool electrode and the workpiece can rotate, and the wprkpiece can move in X or Y direction with worktable. To meet SREDM, we have developed a numerical control synchronous rotary system, in which stepping motor divided driving technology controlled with single-chip micro-computer is applied. Two stepping motors can rotate at any ratio of relative angular 1 2 3 4 5 1-accessory1 2-tool 3-workpiece 4-accessory2 5-worktable Fig.3 the machine apparatus after refitted velocity. They work accurately and steadily. The feed motion can be carried out by Y direction stepping motor of worktable. The main CPU of the system controls the feed motion on the basis of gap voltage, which is supplied by spark condition inspection block. The one pulse motion equivalent of the worktable is 1 m and the stepping motor divided driving technology is added, so the system can exactly trace the spark gap during precision machining. This system is shown in Fig.4. 4. The process and the key of SREDM Before machining, the workpiece and tool electrode are adjusted to the positions which are shown in figure 2. The operation method of the technology is: At first, the two stepping motors that drive the rotation of workpiece and tool are started, then the machining fluids system is opened, at last, the pulse generator is turned on. During machining, in order to sustain the normal spark condition, the feed motion is automatically controlled according to the gap voltage. Not alike conventional EDM, the tool need mot draw back. When short-circuit ratio is high i.e., the gap voltage increases to a certain value, the fed motion is continued. When the desired precision is high, the machining process can be divided into three or more times, the tools are changed and the spark parameters should be rationally selected. rotation rotation motion Workpiece Tool Feed Fig.4 SREDM inspection and control system 5.Conclusions The SRSDM is an optimum technology of machining inner cavity of the precision aerostatics bearings. If the stepping motor divided driving technology controlled by microcomputer is added to the SREDM, the process can easily machine inner cavity of the Main CPU Keyborad display device Stepping moter divided driving Stepping moter divided driving Stepping moter divided driving Spark Condition inspection precision aerostatics bearings with high symmetry precision, and shows simple equipment, convenient operation, low machining costs, etc. In addition, this method can machine other complex surfaces of inner cavity through NC programming. References 1. J.W. powell Design of Aerostatic Bearing. National Defense Industry Publishing House, 1987 2. Yaziwa Kiz Air Bearing-Design. manufacture and application, Aerospace Publishing House, 1988 3. Shun Changshu Generating-Rotary EDM. Proceeding of the 4th Symposium of Chinese EMS, 1983 譯文 一種用同步回轉電火花加工精密軸內孔的方法 哈爾濱工業大學機械工程系 ,夏季強 劉用紅 賈知心 劉竟春 摘要：這篇論文提出一種用數控同步旋轉點火花加工加工精密靜壓軸承的方法。這種方法能夠很容易的精密靜壓軸承精度可達到 10um的對稱性和 Ra0.4um的表面粗 糙度。這 篇論 文 分析了這項技術的 原則和 條件 ，和介紹機器加工儀器和控制系統 。 關鍵字：靜壓軸承 同步旋轉 1介紹 壓力軸承是隨著高科技的出現而發展起來的。它通過油潤滑而使摩擦和磨損變的非常小，不 會產生過多的熱量，有較高的旋轉精度等等。 它被廣泛應用在航空領域，醫療設備和電子工業。 精密靜壓軸承是一種具有高旋轉精度的靜壓軸承。它的特別的孔如圖 1 所示。它被應用于測量儀器和精密車床。靜壓軸承孔的對稱度很高所以它很難加工特別是錐面和球面孔。為了獲得較高的對稱度一般的方法是應用特別的卡具和高精密指針。這些方法需要很高的費用和復雜的操作來生產小系列產品。在這種情況下，數控同步回轉點火花加工應運而生。這種方法能夠用很低的費用來加工高精度靜壓軸承孔。 2同步點火花加工的原理和優點 同步點火花加工的原理如 圖 2 所示。在加工過程中，工件是負極 工具是正極，工具電極以工件兩倍的速度旋轉，同時，電極軸垂 圖 .1 氣壓軸承內孔 圖 .2 SREDM 的原理 直方向的慢進給增加。當工件旋轉一周的時候，工件上相對兩孔的對稱的點已被刀具的同一點加工。由于刀具每周的磨損是可以忽略的，所以它可以被認為兩個孔被刀具的同一點 對稱加工。高對稱度的孔用很少的費用便加工出來了。軸承中的調節槽也可以用同樣的方法加工。 同步點火花加工的條件是 ： D=2d 21 式中： D-洞的直徑 d-刀具電極的直徑 1 -工件的角速度 2 -工具電極的角速度 這種技術的優點是： （ 1）這種 方法能夠加工任何難切削的導電材料，所以材料加工前可以實行淬火并且這種影響可以消除。 （ 2）因為在切削過程中不需要大的切削力，所以不需要高剛度機床。 （ 3）簡單的成型原理使得工藝過程不再依賴高精度指針的卡具。 （ 4）這種方法能夠得到很高的對稱度。 （ 5）這種方法可以獲得較小的粗糙度。 （ 6）應用編程，這種方法能夠加工任何復雜的內孔表面。 3用同步回轉電火花在電火花機床上加工孔 同步回轉電火花加工能夠在增加兩個附件的機床上完成加工 .重新安 置的機器設備如圖 3 所示。 其軸被步進電動機直接驅動的附件 1 被安裝在床身上。 工具電極被安裝在軸上。附件 2 被另一個步進電極驅動 ,它被安裝在機床的 1 2 3 4 5 附件 1 2 刀具 3 工件 4 附件 2 5 工作臺 圖 3 安裝后的加工系統 工作臺上，工件被安裝在它上面的軸上。這兩個軸在同一平面內并且可以在工作臺的X 方向平移，工具電極和工件可以旋轉 ,并且工件可以在工作臺的 X,Y 移動 .。 提到同步回轉電火花加工 ,我們已經應用了一種數控同步 回轉系統 ,其中已經應用了單芯微型電腦控制的步進電機切割驅動技術