A Study Of Corner Cutting Strategy For Wire-EDM

Electric Discharge Machining(EDM)is a new type of nontraditional machin-ing and has been developing for a few decades. Now EDM is heading towards high efficiency, high accuracy and intelligence. Wire Cutting Electrical Discharge Machining(WEDM)is an important research field of non-traditional machining, which deals with materials that are difficult to machine and work piece with complicated surface. In the comer processing by WEDM, the accuracy of cutting comer has always been taken as one of the important properties in WEDM field. During the processing, the wire electrode is subject to vibration and deformation due to explosive forces and electrostatic forces, making the Wire trajectory lag behind the NC trajectory and therefore resulting in error in cutting comer. To improve the accuracy of cutting comer, on one hand reducing wire deformation by reducing the above forces exerted on it and by increasing the tensile force applied by the machine. On the other hand modifying wire trajectory int order to compensate for the wire deformation. Thus this paper analyzes reasons influ-ence on the accuracy of wire-EDM corner cutting, then proposes a simultaneous trajectory and processing parameters control method to improve the accuracy of cutting corner. In order to modify trajectory, the paper describes the develop-ment of NC code interpreter for wire-EDM, which reads NC code and produres calls of a set of canonical machining functions. The set of canonical machining fuctions are modified in corner cutting base on the wire deformation measured from experiment.In order to control the processing parameters, we modify the processing parameters in motion module base on the corner information included in canonical machining fuctions.To verify the accuracy of the combined control method we have conducted a series of verification tests of different corner categories and then compare the experimental results with the system without applied the method. It shows the accuracy improved different level of different corner categories, particularly in processing the "partial discharge" there was a comparatively large error and ap-peared a convex angle phenomenon. The larger error in the machined comer because the small radius concave corner causes easily repetitive discharges be-tween electrode and workpiece and hence influences both of the radius of erased bulb in one discharge and discharge angle. Finally, after the modification of mathematical models, followed experiments verified the feasibility of the com-bined trajectory and processing parameters control method.Base on the study of strategy to improve convex and concave corner accu-rary of rough cuts, which provide help for the continued studies in finish-cutting and taper-cutting.