Finishing on the large area of work surface by EDM using a capacity coupling method

摘要

In this study, the capacity coupling method was applied to the large area EDM to realize glossy surface. In order to obtain glossy workpiece surface by EDM, it is necessary to control the electrical discharge energy per pulse to be small appropriately. However, with the conventional pulse generator, the attainment of pulse control is very difficult, especially in the case of machining to the work surface which has large scale of area, because of gap storage capacitance between the electrode and the work surface, even if not so much power supply. With this capacity coupling method, a pulse generator is coupled with a tool electrode by a feeding capacitance, and the electrical discharge energy per pulse can be reduced by decreasing the feeding capacitance. In addition, the influence of the working gap capacitance between tool electrode and work piece can be eliminated, thus the discharge energy can be reduced to realize glossy surface. In this study, the charge and the discharge characteristics of the working gap with this method were investigated when the work surface has large scale of area. It was confirmed that the discharge energy per pulse can be reduced to small enough and the glossy surface was obtained.