Patent ID: 7950261

Claim:
A press forming method for a sheet material, in which an upper die provided with one of a plurality of dies for drawing a sheet material and one of a plurality of secondary working members separate from the dies, which perform secondary working, which comprises at least one of trimming, piercing, burring, bending, or coining of the sheet material, is lowered with respect to a lower die provided with another one of the dies and another one of the secondary working members, and in which the upper die is provided with an upper drawing die, a pierced hole periphery die having a concave portion for coining, a punch, and an upper blank holder is lowered with respect to a lower die provided with a lower drawing die having a punch housing hole, a coining punch, a lower blank holder, and a trimming member also used as a blank holder, wherein the sheet material is substantially formed during a single cycle of pressing operation; wherein the outer periphery portion of a blank placed on the trimming member is held by the trimming member and the upper blank holder; successively, the outer periphery portion of the blank is trimmed by the upper drawing die and the lower blank holder; successively, overall forming by drawing of the blank is started in cooperation by the upper drawing die and the lower drawing die; successively, the pierced hole periphery portion of the blank is drawn in cooperation by the pierced hole periphery die and the lower drawing die by moving the pierced hole periphery die downward under pressure; successively, the blank is pierced by the punch and the punch housing hole, successively, coining of the blank is started by the coining punch and the concave portion for coining; and as the upper die reaches the bottom dead center, the overall forming and coining of the blank are completed.