Fundamental Study of Accuracy of Wire EDM (2nd Report)

This present paper investigates about accuracy of rough convex corner and convex corner R. Previous some reports proposed methods to improve corner and corner R accuracy of wire EDM. One method controls EDM conditions and other method modifies a program path at the corner and corner R, and 3rd method is a on-line system which detects wire deflection and corrects a contouring path. But 1st method has problems that the corner accuracy is insufficient and it lacks details to decide EDM parameters. Also 2nd method has a problem that the accuracy on top surface differs from that on middle cross section surface of a work piece. In addition 3rd method is only useful for special machines. In this paper we propose a combined power and path control method to improve the convex corner and corner R accuracy which is useful for ordinary operators. In the method, discharge power is adjusted so that the error of convex corner and corner R on the top or bottom surface of the work piece decreases within a desired value. The program path is corrected so as the residual error on the middle surface of the work piece to be 0.