| 摘要 |
PURPOSE:To improve the accuracy of a groove dimension, to make it unnecessary to execute an after working, etc., and to improve the productivity, by restricting a flow of a material in the axial direction of a cup part, at the time of pressing the cup part. CONSTITUTION:A cup part 5 of a preform W is placed on a mandrel 6,... and contained in a die, and thereafter, an upper die 10 is made to descend and a punch 12,... is moved in the direction of a preform 5 by a cam surface 11a of a fixed cam 11, and an outside peripheral surface of the cup part 5 is pressed. At the same time, a piston 14a is made to descend by supplying a hydraulic pressure to a hydraulic mechanism 14 and a back face 5d of the cup part 5 is pressed by a work holder 13. Also, by a restricting part 8a of a knockout plate 8 which has been provided on a lower die 4, an elongation of an end face 5b of the cup part 5 is restricted. In this way, by pressing the back face 5d of the cup part 5, and restricting the end face 5b side, a distribution of a working pressure in the preform becomes roughly constant. Therefore, after forming, a variation of wall thickness caused by spring-back, etc. is suppressed small, and a groove having a high dimension accuracy is formed. |
