一种用同步回转电火花加工精密轴内孔的方法外文文献翻译@中英文翻译@外文翻译

附录 A英文翻译 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 译文 一种用同步回转电火花加工精密轴内孔的方法 哈尔滨工业大学机械工程系 ,夏季强 刘用红 贾知心 刘竟春 摘要：这篇论文提出一种用数控同步旋转点火花加工加工精密静压轴承的方法。这种方法能够很容易的精密静压轴承精度可达到 10um的对称性和 Ra0.4um的表面粗 糙度。这 篇论 文 分析了这项技术的 原则和 条件 ，和介绍机器加工仪器和控制系统 。 关键字：静压轴承 同步旋转 1介绍 压力轴承是随着高科技的出现而发展起来的。它通过油润滑而使摩擦和磨损变的非常小，不 会产生过多的热量，有较高的旋转精度等等。 它被广泛应用在航空领域，医疗设备和电子工业。 精密静压轴承是一种具有高旋转精度的静压轴承。它的特别的孔如图 1 所示。它被应用于测量仪器和精密车床。静压轴承孔的对称度很高所以它很难加工特别是锥面和球面孔。为了获得较高的对称度一般的方法是应用特别的卡具和高精密指针。这些方法需要很高的费用和复杂的操作来生产小系列产品。在这种情况下，数控同步回转点火花加工应运而生。这种方法能够用很低的费用来加工高精度静压轴承孔。 2同步点火花加工的原理和优点 同步点火花加工的原理如 图 2 所示。在加工过程中，工件是负极 工具是正极，工具电极以工件两倍的速度旋转，同时，电极轴垂 图 .1 气压轴承内孔 图 .2 SREDM 的原理 直方向的慢进给增加。当工件旋转一周的时候，工件上相对两孔的对称的点已被刀具的同一点加工。由于刀具每周的磨损是可以忽略的，所以它可以被认为两个孔被刀具的同一点 对称加工。高对称度的孔用很少的费用便加工出来了。轴承中的调节槽也可以用同样的方法加工。 同步点火花加工的条件是 ： D=2d 21 式中： D-洞的直径 d-刀具电极的直径 1 -工件的角速度 2 -工具电极的角速度 这种技术的优点是： （ 1）这种 方法能够加工任何难切削的导电材料，所以材料加工前可以实行淬火并且这种影响可以消除。 （ 2）因为在切削过程中不需要大的切削力，所以不需要高刚度机床。 （ 3）简单的成型原理使得工艺过程不再依赖高精度指针的卡具。 （ 4）这种方法能够得到很高的对称度。 （ 5）这种方法可以获得较小的粗糙度。 （ 6）应用编程，这种方法能够加工任何复杂的内孔表面。 3用同步回转电火花在电火花机床上加工孔 同步回转电火花加工能够在增加两个附件的机床上完成加工 .重新安 置的机器设备如图 3 所示。 其轴被步进电动机直接驱动的附件 1 被安装在床身上。 工具电极被安装在轴上。附件 2 被另一个步进电极驱动 ,它被安装在机床的 1 2 3 4 5 附件 1 2 刀具 3 工件 4 附件 2 5 工作台 图 3 安装后的加工系统 工作台上，工件被安装在它上面的轴上。这两个轴在同一平面内并且可以在工作台的X 方向平移，工具电极和工件可以旋转 ,并且工件可以在工作台的 X,Y 移动 .。 提到同步回转电火花加工 ,我们已经应用了一种数控同步 回转系统 ,其中已经应用了单芯微型电脑控制的步进电机切割驱动技术