| 摘要 |
PROBLEM TO BE SOLVED: To perform electric discharge machining of chamfering of the punch guide hole of the press device of a mold device without preparing an electrode and further, to perform automatic chamfering in an excellent shape with high productivity even when a punch guide hole is fine and the number of the holes is large. SOLUTION: In a method wherein chamfering is effected through electric discharge machining of the punch guide hole of the press device of a mold device to effect blanking by forward and backward movement of a punch with a material to be punched pressed against the die side, electric discharge machining is effected in reverse polarity wherein a non-molded electrode 1 forms a plus pole and a press device 2 forms a minus pole. The opening shape of a punch guide hole 3 is transferred to the electrode 1 for formation and consecutively, electric discharge machining is carried out, and the punch guide hole 3 is chamfered through the transfer shape of the electrode 1.
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