| 摘要 |
A punch for use in molding a workpiece with lubricating oil interposed between the punch and the workpiece includes a straight portion at its end and a diameter-increasing portion. The straight portion includes an end face at its end and a side face. The straight portion extends in an axial direction. The end surface extends in a radial direction perpendicular to the axial direction. The side surface is connected to the end surface. The diameter-increasing portion is connected to the straight portion. The diameter-increasing portion includes a width in the radial direction, which is identical to that of the straight portion, at a junction between the straight portion and the diameter-increasing portion. The width of the diameter-increasing portion in the radial direction increases with distance from the straight portion. At least one of the end surface and the side surface of the straight portion is formed with a pit.
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