HYDROFORMING METHOD AND HYDROFORMED COMPONENT

摘要

Disclosed is a method for hydroforming a component having a long tube-expanding region such that no buckling nor wrinkle remains.  A first step for expanding the portion of a metal tube near the end thereof is carried out by boosting the internal pressure in a state where the metal tube is fixed at the opposite end positions thereof or in a state where axial pushing force of 10% or less of the total axial pushing force is applied to the metal tube, and then axially pushing the metal tube while the internal pressure is maintained at a fixed level, followed by a second step for expanding the central part of the metal tube by boosting only the internal pressure without axial pushing, and a third step for subsequently lowering the internal pressure down to the above fixed level.  Then, after repeating the first through third steps onece or a plurality of times, the internal pressure is boosted in a state where axial pushing is not performed or axial pushing force of 10% or less of the total axial pushing force is applied, thus obtaining a hydroformed component.