| 摘要 |
In a press forming step of obtaining, from a blank (300) of high-tensile strength steel sheet of 390 MPa or more, a press-formed product with a shape of cross section having at least a groove bottom part (101), ridge line parts (102), and vertical wall parts (103), and in which an outward flange (106) including parts (106a) along the ridge line parts (102) is formed at an end part in a longitudinal direction, forming of parts to be formed to the ridge line parts (102) is started by creating a state where a region (300a) positioned at least at an end portion in a longitudinal direction of a part to be formed to the groove bottom part (101) of the blank (300) is separated from a punch top part (201b), and at that time or thereafter, the region (300a) is made to approach the punch top part (201b). Accordingly, when the forming of the ridge line parts (102), and in accordance with that, the forming of the parts (106a) of the outward flange (106) are conducted, the parts are formed relatively moderately from the start to the middle of the press forming, to thereby reduce or prevent an occurrence of stretch flange fracture and a generation of wrinkling. |
