Patent ID: 8596105

Claim:
A punch for use in molding a workpiece with lubricating oil interposed between the punch and the workpiece, the punch comprising: a straight portion at an end of the punch, the straight portion extending in an axial direction, the straight portion comprising: an end surface at an end thereof, the end surface extending in a radial direction perpendicular to the axial direction; and a side surface connected to the end surface; a base material; a coating film formed on the base material on at least one of the end surface and the side surface of the straight portion, the coating film having hardness greater than that of the base material; and a diameter-increasing portion connected to the straight portion, the diameter-increasing portion comprising a width in the radial direction, which is identical to a corresponding width 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 increasing with distance from the straight portion, wherein the coating film is formed with a plurality of concave pits configured to retain lubricating oil, each of the pits including an opening formed therein configured to receive such lubricating oil.