Development of Ultra Precision Fine EDM Device for Micro Machining

本课题从1995年4月至1998年3月进行了3年的研究，目的是研制一种用于微细加工的超精密精密电火花加工装置。第一年，我们尝试制作了一台超精密的微细电火花加工机床，并完成了适合微细加工的电容电路机床。第二年，提出了一种利用简单电极高效加工复杂形状的新方法，并开发了直角等边三角形长细电极的挤压加工方法。由于银易于挤压和电火花加工的性能，因此选用银作为电极材料。在第三年，用挤压成形电极尝试了几种复杂形状的加工。首先通过简单的冲孔实验，研究了加工结果与加工条件的关系。然后，结合直角三角形，尝试了一些多边形、星形和字母的加工。该方法通过在显微镜下排列坐标，实现了高精度的微加工。然后，针对不可能使圆角半径如此小的问题，提出了圆角半径的减小方法。结果表明，通过反向电火花加工可以将拐角半径减小到10-25微米。研究了用相同的反向电火花加工方法使角小于45度的方法。在此基础上，对型腔的加工进行了试验，证明其是可行的。最后，对单晶硅的微加工进行了研究。证明了硅可以像不锈钢一样被加工，并表明该方法对单晶硅微传感器和执行器的微加工是有效的。

This study has done for 3 years from Apr.1995 to Mar.1998 in order to develop a ultra precision fine electric discharge machining device for micro machining. In the first year, we tried to make a ultra precision fine EDM machine, and completed the machine with condenser circuit which was suitable for fine micro machining. In the second year, a new method for high efficiency machining of complicated shape using simple electrode was proposed, and the the extrusion method for long fine electrode with a right angled equilateral triangle was developed. Silver is used as the material of electrode because of the easiness of extrusion and the performance of EDM.In the third year, some kinds of machining of complicated shapes are tried with the shaped electrode made by extrusion. First the relationship between the machining result and the machining condition was investigated by simple piercing experiment. Next, machinings of some polygon shapes, star shape and letter were tried by combining the right angled triangles. In the method, the coordinates were arranged under the microscope, which led to the precision micro machining. Then, the reduction method of corner radius was proposed, because it was impossible to make the corner radius so small. It was clarified that the corner radius could be reduced to 10-25micron by the reverse EDM.The method to make the corner angle less than 45 degrees was also investigated and it was shown that it was possible by the same reverse EDM method. Furthermore, the machining of cavity was tried, and it was shown to be possible. Lastly, the micro machining of single crystalline silicon was investigated. it was proved that silicon could be machined like the stainless steel, and it was shown that this method was effective for micro machining of micro sensors and actuators made of single crystalline silicon.