| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for die design and a method for press molding, by which spring back during press molding can be efficiently reduced. <P>SOLUTION: When press-molding a press molding item 11 having a nearly hat-like cross section, a recessed or projected bead 16 is given to a bottom wall 12 to reduce such a tensile stress of a flange 15 before mold releasing that is a factor causing torsion due to spring back. In concrete terms, a bead-molding projecting section or a bead-molding recessed section for forming the projecting bead 16 is provided at a part corresponding to a punch bottom of a molding die. Thus, a material of the flange 15 is put into the side of the punch at a bottom dead center in the middle of press molding, to mold the projecting bead 16, thereby easing tensile stress indirectly by the compressive stress generated at the flange 15 as a result. <P>COPYRIGHT: (C)2013,JPO&INPIT |
