| 摘要 |
PROBLEM TO BE SOLVED: To provide a press forming method for preventing warping and twisting of a longitudinal wall part occurring in a press-formed product. SOLUTION: The press forming method is provided for press-forming a member having a U-shaped section or a V-shaped section at least in a part thereof, wherein in a first pressing step, a recess having the predetermined length L1 and width and depth is press-formed so that horizontal sections of a pair of longitudinal wall parts 11, 11 form closed sections, and thereafter, at least one press forming is performed so that the length L2 in the longitudinal direction of the longitudinal wall parts 11, 11 is increased (L2>L1), and thereby the residual stress due to the press forming is mitigated, and the spring-back can be considerably reduced. In the press forming step of increasing the length of the longitudinal wall parts 11, 11, a three-divided punch having a punch of a wedge shape 5 in a center part may be used. Thereafter, trimming is performed so that ends of the longitudinal wall parts form a product shape of an open section. COPYRIGHT: (C)2009,JPO&INPIT
|
