Patent ID: 7614271
Filing Date: 2009-11-10
Classification: B21D,Y10T

Abstract:
1. A hydroforming method comprising the steps of: disposing a preform inside forming dies having cavity surfaces that correspond to an outer shape of a hydroformed product; and applying a hydraulic pressure in an inside of said preform to form reinforcement ribs that divide a hollow cross section of said hydro formed product, in which said preform comprises first and second outer members composed of sheet materials having edges overlapped and jointed to each other for forming outer surfaces of the hydroformed product, and reinforcement members composed of a sheet material jointed to said first and second outer members to form said reinforcement ribs, said reinforcement members having a plurality of openings that are disposed in a staggered pattern and can be expanded by inflating deformation during hydroforming, in which said reinforcement ribs are formed by suppressing a fracture of said reinforcement members caused by elongations of said reinforcement members in a tensile direction due to a tensile force developed during inflating deformation of said preform as a result of expansions of said openings.