Development of WEDM Simulation with Parameters Adaptively Changed using Wire Electrode Displacement Sensor

Abstract

During wire electrical discharge machining (WEDM), various forces like discharge reaction force, electrostatic force, electromagnetic force, and drag force due to fluid flow cause vibration and deflection of the wire electrode. The generated vibration and deflection of the wire electrode exert a large impact on machining accuracy. Therefore, to achieve higher machining accuracy, a WEDM simulation was developed to calculate the behaviors of the wire electrode during machining to obtain the workpiece shape. In the simulation, parameters which are difficult to measure directly, such as the discharge reaction force and drag force, were obtained from the inverse problem method so that the vibration and deflection of the wire electrode measured using an optical sensor coincided with the calculated ones in the simulation. Since these parameters may change during machining even under the same discharge pulse conditions depending on the cutting depth, workpiece thickness, and curvature of the machining path, the parameters should be changed adaptively based on the wire behaviors measured in the process. In this study, the WEDM simulation with parameters adaptively changed was applied to the machining of a stepped workpiece and the accuracy of the simulation was evaluated. Although there were certain errors in the kerf width and wire feed speed between the simulation and real machining, the changes in the kerf width and feed speed could be reproduced qualitatively. The necessary to improve the simulation strategies was discussed to realize higher accuracy.