Detection of Electric Discharge Machining State By Using Ultrasonic Technique

The electric discharge die-sinking is widely used in order to make a mold and so on. In the electric discharge die-sinking, an electric discha rge occurs between an electrode and a workpiece. When a lot of debris exists at the discharge gap, the electric discharge becomes abnormal. Therefore, in this study, a detection method o f the electric discharge die-sinking state by using an ultrasonic technique has been examined in or der to prevent the abnormal discharge. In this study, the following results have been obt ained. (1) The discharge gap can be measured by using the pulse echo technique during the electric d ischarge die-sinking. When the abnormal electrical discharge occurs, the gap becomes large. (2) The abnormal discharge can be detected by the variation of the received elastic waves which are generated at a discharged point and transmitted through the workpiece. (3) The depth of the hole machined by die-sinking can be measured by using the pulse echo technique during machining. (4) The abnormal discharge can be prevented by vibrating the electr ode by an ultrasonic vibration.