PURPOSE: To form a torsion part in a hollow stock with high precision by providing a part for increasing a moving speed of a billet in an outside peripheral part of the torsion part, in the end face which faces a male die of a bearing part in a female die.
CONSTITUTION: A billet B is charged in a container 31 and pressed, and moved to the inside of a stock leading-in part 16 of a female die 12. Also, it moves between a center bar 15 of the female die 12 and each torsion part 19 of a die hole 18a of a bearing body 18. An opening end part for facing the stock leading-in part 16 in each torsion part 19 in the female die 12 is inclined from the upstream side in the billet B moving direction to the downstream side extending from the center to the outside peripheral edge. In such a way, the billet B flows in easily in the outside peripheral part, and a speed at which the billet B moves along the outside peripheral part of each torsion part 19 becomes higher than a conventional speed. In such a state, the billet B is formed as a hollow body 1 having a torsion part in the outside peripheral part.
TAKASUGI ATSUMI
TAMURA SUSUMU
WATANABE TOSHIO
