Spatial Planetary Movements for Multi-Axis EDM

Abstract

Multi-axis electrical discharging machining (EDM) is the most commonly used manufacturing method for shrouded blisks. However, debris is difficult to be evacuated from a discharge gap, thus severely affecting the machining efficiency. Spatial planetary movements of a tool electrode can generate a non-uniform flow field in the discharge gap, promoting the evacuation of debris. This paper proposes a spatial planetary movement method for a feeding path of spatial line segments. Screw theory is used to derive the kinematics of a spatial planetary movement, and the coordinate increments of each axis in an interpolation period can be calculated. Then a multi-axis EDM machine can be controlled to drive a tool electrode to realize the spatial planetary movement. Machining experiments are carried out to explore the influences of the spatial planetary movement parameters on the machining performance of multi-axis EDM. Experiment results show that spatial planetary movements can improve the machining efficiency of multi-axis EDM, and the increase in the radius and speed of spatial planetary movements can further improve the machining efficiency. The machining efficiency can be increased by 51.62% and 50.44% respectively.