Preform, hydroforming method, and hydroformed product

摘要

A preform with edges overlapped and jointed each other and first and second outer members (10,20) for forming outer surfaces (61,62) of a hydroformed product, and reinforcement members (30,40) that are jointed to the first and second outer members (10,20) to form reinforcement ribs (63,64) that divide a hollow cross section of the outer surfaces (61,62), the reinforcement members (30,40) having dimensions capable of suppressing elongation in a tensile direction due to a tensile force that develops during hydroforming. The invention also relates to a hydroforming method and a hydroformed product.