Proposal of six-axis micro wire electrical discharge machine tool based on novel direct drive rotation wire frame mechanism

Abstract

This article introduces a novel highly integrated direct drive rotation wire frame mechanism for multi-axis micro wire electrical discharge machine tool. The design allows the micro electrode wire center to rotate along the motor's output shaft by ±90°, enabling machining over a complete circular area. This enhances the rotation precision and reduces the displacement of each axis, ensuring that the length of the electrode wire remains unchanged during the rotation process and thereby maintaining a stable friction force with the V-grooves. Building upon the direct drive rotation wire frame, a six-axis micro-wire electrode discharge machining machine has been developed, facilitating multi-axis coordinated processing. This study establishes the forward and inverse kinematic models using homogeneous transformation matrices to describe each axis's motion of the machine tool. A closed-form solution for the inverse kinematic model has been derived and effectively utilized for machining path planning for the electrode wire. To comprehensively characterize the machine tool's performances, a method that combines coordinate transformation, analytical geometry, and the Monte Carlo approach has been employed to determine the actual working space and the dexterity of the machine tool. Finally, a preliminary experiment with the six-axis micro wire electrical discharge machine tool demonstrates the effectiveness of the proposed direct drive rotation wire frame, verifying the inverse kinematic closed-form solutions, the practical workspace of the machine tool, and the effectiveness of dexterity and geometric error modeling.