| 20100071434 | PRESS FORMING METHOD FOR METAL SHEET AND FRAME PART FOR AUTOMOTIVE BODY MANUFACTURED THEREBY - A press forming method for a metal sheet is provided. The method is capable of improving a forming limit at which a crack appears in a metal sheet and being easily applied to a large press machine for mass production with a low cost, without correcting the shape of dies, such as a punch and an upper die, or changing the shape or material of a blank to a special shape or material. Dies, a surface roughness of which is an arithmetical mean roughness Ra of 7.5 μm or smaller, are used as a punch, an upper die, and a blank holder. Fluid with a kinematic viscosity of 500 mm | 03-25-2010 |
