An Ultrasonic Vibration Assisted Electrical Discharge Machining Device with Workpiece Vibration

ABSTRACT For solving the problem of machining micro deep hole in hard material, an ultrasonic vibration assisted electrical discharge machining (UV-EDM) device with workpiece vibration was designed and fabricated. The piezoelectric vibrator which had appropriate longitudinal mode and frequency was designed and tested. The first-order longitudinal vibration frequency of the piezoelectric vibrator was 21450 Hz, and the vibration velocity of the piezoelectric vibrator head was about 24 mm/s.Then the influence of ultrasonic vibration on the EDM machining of micro deep hole in die steel was studied. Experiments showed that the efficiency of ultrasonic EDM based on workpiece vibration was higher than that of traditional EDM. The orthogonal experimental design was used to optimize the process parameters. The machining depth was set as the experiment index. Four process parameters, including excitation voltage , pulse current, pulse width and pulse gap, were selected as the experimental factors. The influence degree of the four process parameters on the machining depth was obtained by optimization. And the best level combination of process parameters were obtained. Through the analysis of variance, the interval estimation of the optimal combination was carried out, and the confidence degree of the interval estimation was given. The test result indicated the micro deep hole with diameter Φ0.5mm and high aspect ratio 67 could be drilled effectively with optimized process parameters. The theoretical and experimental results showed that the proposed UV-EDM was valuable in machining micro deep holes with high aspect ratio in hard materials.