To provide a punching method by a shoulder type punch by which high fatigue strength can be obtained, and seizure and wear of the punch upon working are hard to occur, and to provide a shoulder type punch.
A hole working method is disclosed for punching a prepared hole having a diameter smaller than that of an objective hole being a final shape and similar to the objective hole, then expanding the prepared hole so as to have the diameter of the objective hole, wherein a die and a punch for a prepared hole which has a blade edge of a radius of curvature of 0.5 mm are used, an amount of a stroke of the punch after contacting with a workpiece is controlled to 20 to 80% of the sheet thickness of the workpiece, and the prepared hole is punched which has a diameter smaller than the diameter of the objective hole by a length equivalent to the 1/20 to 2/3 of the clearance between the punch for the prepared hole and the die. Thereafter, a punch for diameter enlarging is used which has a bottom face with a diameter equal to or smaller than the diameter of the punch for the prepared hole and has a diameter enlarging part with a tapered shape made thick to a diameter same as that of the objective hole, the amount of the stroke of the punch after contacting with the workpiece is controlled to 10 to 40% of the sheet thickness of the workpiece, and the prepared hole is expanded to the objective hole.
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| JP2000343142 | PRESS DEVICE |
SETO KOJI
NITTA ATSUSHI
KURIYAMA YUKIHISA
SATO KOICHI
| JPS6182937A | 1986-04-26 | |||
| JPS59183798U | 1984-12-07 |
Tetsuo Kanamoto
Miaki Kametani