dc.description.abstract | This thesis is an investigation of ultrasonic-assisted electrochemical machining of the micro-hole array. In this study, one-piece array electrode assisted by ultrasonic vibration is used to produce micro-hole array on 301 stainless steel plate. The effects of processing parameters such as ultrasonic amplitude, working voltage, pulse off time and electrode feed rate on quality characteristics. The quality characteristics including average diagonal length, diagonal length variation, inlet taper angle and outlet taper angle were discussed.
The experimental results indicate that the ultrasonic vibration electrode generates a periodic pressure difference to the electrolyte. This periodic pressure difference forms the pumping effect and the cavitation effect. The pumping effect causes a wide range of electrolytes to be sucked into and pushed out off the machining gap. Besides, the periodic pressure difference leads to a cavitation effect, which produces microbubbles. Once the microbubble collapse, it produces a microjet which disturbs a small range of electrolytes instantaneously. Both effects can effectively refresh the electrolyte in the machining gap, supply the ions consumed in the electrochemical reaction, and exhaust the solid reaction products, gases, and reaction heat in the gap. The phenomenon enhances the processing speed and reduces the average diagonal length of micro-hole array. By using ultrasonic-assisted electrochemical machining micro-hole array, when the ultrasonic amplitude is increased from 0.94 μm (power of ultrasonic vibration lv.1) to 2.87 μm (power of ultrasonic vibration lv.1), the processing speed can be improved by more than 500%. Processing under the experimental optimal parameter, such as the power of ultrasonic vibration level 9 (2.87μm), working voltage 11V, pulse off time 50μs and electrode feed rate 5μm/s, can obtain the minimum average diagonal length of 1200μm and smaller diagonal length variation of 44μm. It also improve the inlet and outlet taper angle of micro holes. | en_US |