| 摘要 |
PROBLEM TO BE SOLVED: To maintain productivity and to provide a method and an apparatus for punching a forged product capable of easily forming a penetration hole by punching at the prescribed position. SOLUTION: In the punching method by forming a penetration hole penetrating in the axis direction, a pre-forged material is formed for having a curve surface 7a with a smaller diameter along the axis direction, or a recess 7 or a protrusion with a taper surface in the range of punching, and afterward, the penetration hole is formed by punching the recess or protrusion of the pre-forged material W1 by a punch having a protruded press part 33 or a recessed press part, which is engaged to the recess 7 or the protrusion at the edge side opposite to the pre-forged material W1. COPYRIGHT: (C)2003,JPO
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