Simulation of Die-Sinking EDM by Discharge Location Searching Algorithm

本研究针对电火花成形加工中工件几何形状的模拟问题，采用一种新开发的模拟算法，忠实地模拟了差距中发生的实际现象。该算法是一个简单的重复的过程，其中包括：1。确定介电击穿强度最低的下一个放电位置，2.移除工具和工件电极，3.分散碎片颗粒，以及4.进给工具电极。该模拟考虑了各种影响因素，如工具电极磨损，间隙宽度分布，曲率和工具电极的倾斜度，以及碎片颗粒浓度，所有这些都以非常复杂的方式相互影响。对加工后的工具电极和工件的几何形状以及加工后的差距宽度分布的仿真结果与加工平面和正方形表面的实验结果吻合良好。本研究的另一个目的是发展一种仿真方法来解决逆问题，其中工具电极形状可以获得最终的工件形状。在该逆模拟中，考虑到工件和工具电极的初始形状等于它们在正向模拟中的最终形状，使用与上述正向模拟中使用的相同算法。此外，工件在相反方向上朝向工具电极进给，并且关于分别属于工具电极和工件的每个脉冲放电的去除体积的数据彼此交换。作为逆模拟的结果，工具电极和工件的形状被恢复到正模拟中的初始形状。

This research deals with simulation of workpiece geometry eroded by a die-sinking EDM using a newly developed simulation algorithm for faithful imitation of the actual phenomena which are occurring in the gap. The algorithm is a simple repetition of the procedure which is comprised of : 1. determining the next discharge location where the dielectric breakdown strength is lowest, 2. removing the tool and workpiece electrodes, 3. distributing the debris particles, and 4. feeding the tool electrode. The simulation takes into account a variety of influential factors such as tool electrode wear, gap width distribution, curvature and inclination of the tool electrode, and debris particle concentration, all of which affect each other in a very complex manner. The simulation results for the geometries of the tool electrode and the workpiece after machining and for the gap width distribution agree well with the experimental results for machining of a flat and square surface.Another aim of this research is to develop a simulation method to solve the inverse problem in which the tool elctrode shape to achieve the final shape of the workpiece can be obtained. In this inverse simulation, the same algotithm as used in the forward simulation which is described above is used considering the initial shapes of the workpiece and tool electrode as equal to their final shapes in the forward simulation. Moreover, the workpiece is fed in the opposite direction toward the tool electrode, and the data concerning the removal volumes per pulse discharge pertaining to the tool electrode and workpiece, respectively, are exchanged each other. As result of the inverse simulation, the shapes of the tool electrode and workpiece were restored to the initial shapes in the forward simulation.