EDM milling based on a 6-DOF serial robot

Aim: ing at the problems of insufficient flexibility and limited size of workpiece in traditional EDM milling, an EDM milling method based on 6-DOF serial robot is proposed in this paper. To realize the rapid adjustment of machining gap, a tool electrode servo motion device was invented and installed at the end of a 6-DOF serial robot and a servo control strategy of tool electrode vertical trajectory fallback was proposed. Then, to achieve the controllable thickness of every layer in EDM milling based on 6-DOF serial robot, the servo control strategy of limited motion of the tool electrode on the basis of vertical servo control and a fix-length compensation method to compensate the tool electrode wear were proposed. Finally, to verify the correctness and effectiveness of servo control strategy and wear compensation of tool electrode, the trapezoidal groove structures on the plane workpiece and cylindrical workpiece were machined by EDM milling based on 6-DOF serial robot, respectively. Also, to verify the machining ability of complex trajectory on the space surface of workpiece of EDM milling based on 6-DOF serial robot, three complex trajectories, such as EDM, Chinese character ‘China’ and ‘Chinese knot’, were designed and machined on the hemispherical workpiece with the radius of 38 mm. The feasibility and effectiveness of EDM milling technology based on 6-DOF serial robot were verified, which has great market application potential.