| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric discharge apparatus A in which variations of thrust-out length of a welding rod after having pierced a workpiece is prevented. SOLUTION: The electric discharge machine A is equipped with a discharge power source 21, and a target 3 which is disposed in an insulated state to abut on an electrode rod 101 within a hole 100 of a workpiece 10 at a predetermined penetration place, and an electrode rod.target contact detection circuit 6 which detects contact of the electrode rod 4 and the target 3, and a workpiece.target contact detection circuit 7 which detects contact of the workpiece 10 and the target 3. While a communicating hole 23 which passes from an outer wall of the workpiece 10 to the hole 100 of the workpiece 10 is formed by an electric discharging, non-contact state of the workpiece 10 and the target 3 is monitored by the workpiece.target contact detection circuit 7, and also a control unit terminates the electric discharging when a contact of the electrode rod 4 and the target 3 is detected by the electrode rod.target contact detection circuit 6.
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