| 摘要 |
PURPOSE:To safely stop an electrode without causing the occurrence of a thrust of the electrode, by providing a control circuit to an electric discharge machining device and instantaneously returning the electrode reversely to its moving direction at detection of a contact between the electrode under movement and a work. CONSTITUTION:Electric voltage Vg applied across an electrode 4 and a work 1 is converted to voltages -Vg, Vg through an inverting amplifier and no-inverting amplifier. The amplifiers are switched by analog switches 41, 42 in accordance with a moving direction of the electrode 4. The voltage -Vg or Vg is transmitted to a differentiating circuit constituted by resistors R3, R4 and a capacitor C1. This differentiated voltage E2 and an output E1 from a phase discriminator circuit 32 are added to obtain motor driving voltage epsilon. epsilon is voltage added with E1 and E2 and transmitted to motors 8, 9, 10 through an amplifier 33. In this way, the electrode 4 can be instantaneously returned reversely to the direction the electrode 4 has moved before by a contact between the electrode and the work 1. |
