Direct Measurement of Electrode Movement During Electrical Discharge Machining by Means of Automatic Discharge Gap Controller
Masahiko Kita, Tohru Ishida, and Yoshimi Takeuchi
Department of Mechanical Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan
This study deals with the development of a new method of directly measuring the movement of an electrode during normal electrical discharge machining (EDM) and the movement of an electrode during EDM by means of an automatic discharge gap controller (ADGC) devised by our research group. The ADGC, which mainly consists of a bidirectional actuator using a shape memory alloy (SMA) and an electrode and power supply for EDM, can sustain stable EDMby autonomously and automatically controlling the position of the electrode to keep the discharge gap appropriate. However, the movement of the electrode being controlled by the ADGC cannot be directly measured due to itsminute, high-speed, vibration-like movements inside the working fluid during EDM. This means that there is no way to prove that the ADGC actually controls the position of the electrode so as to maintain a suitable discharge gap for continuing stable EDM. This also means that there is no way to evaluate the movement of the electrode quantitatively and to design or optimize the structure of an ADGC so as to give the ADGC the desired or best performance. Therefore, a method to directlymeasure the electrodemovement by an ADGC is devised in this study. The results obtained in the measurement experiments using this method of measurement prove that the ADGC actually moves its electrode to achieve stable EDM, and they allow the movement of the electrode to be evaluated quantitatively.
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