Self-running type electrical discharge machine using impact drive mechanism

Summary form only given. Electrical discharge machining (EDM) is one of the best ways to machine fine structures because tools do not break, no burr is generated, and machinability does not depend on the hardness of a conductive workpiece. A self-running electrical discharge machine is developed to machine fine structures on a local area of a large workpiece. This electrical discharge machine consists of two parts: a 3-DOF mobile table and a 2-DOF electrode feeding device. The whole machine measures about /spl phi/140/spl times/140 mm and weighs 700 g. This machine moves on a workpiece with the impact drive mechanism which utilizes rapid deformations of piezoelectric elements. A control method of the table is introduced. The direction of the movement of the mobile table depends on the ratio of the applied voltage to each piezo driver. The machining performance is investigated experimentally. The steps of the mobile table is 0.5 /spl mu/m in the x and y directions 0.1 /spl mu/m in the z direction, and 20 /spl mu/rad in the /spl theta/ direction. The rate of the driving pulse is 90 Hz. The mobile table can move both on a dry and a wet surface. There is no interference of the movement among the axes in case of driving in the z or /spl theta/ directions. Machined holes and grooves with the electrical discharge machine of the self-running type are demonstrated. The motion accuracy without a guide is approximately 0.5 mm and 0.4 deg.