Study on motion and distribution of debris in USV-MF complex-assisted WEDM-LS

摘要

The shape of the gap is narrow and thin in low-speed wire electrical discharge machining (WEDM-LS) workpiece with large thickness; it is likely that a lot of debris cannot be removed out of the gap in time, or even accumulate somewhere, which causes a poor machining stability and low processing efficiency. In this paper, ultrasonic vibration (USV) and magnetic field (MF) complex-assisted techniques are combined with WEDM-LS to improve the machining performance. The velocity and pressure of the flow field in USV-assisted WEDM-LS are analyzed according to the theory of fluid mechanics. The fluid-solid coupling model of electrode wire and working fluid, the two-phase flow model of the working fluid, and the debris are established in COMSOL Multiphysics software, and the influence of different amplitudes on motion and distribution of debris is analyzed. It is indicated by the simulation results of debris motion that the exclusion rate of debris increases by 22.5 and the debris are distributed more evenly in the discharge gap. The experiment of a USV-assisted WEDM-LS machining workpiece with large thickness is conducted. It shows that the probability of abnormal electrical discharge reduces obviously and the distribution of discharge point is more uniform, which increases the pulse utilization and discharge efficiency. In addition, the material removal rate (MRR) increases by 44.4, the surface roughness value (Ra) reduces by 12.8 on average, the number of debris recast to the surface decreases significantly, and the micro-cracks on the machined surface of the workpiece decrease in USV-assisted WEDM-LS.