Patent ID: 9669444
Date: 2017-06-06
CPC Classifications: B21C,B21D,B23K

Claim:
1. A method of manufacturing a closed structure part having a curvature and welded edges along a longitudinal direction of the part, and having a varying cross-sectional shape, from two metal plates, comprising: press forming each of the two metal plates, which are provided with a curvature along a longitudinal direction of each of the metal plates corresponding to the curvature of the part along the longitudinal direction and further provided with both ends in a width direction of each of the metal plates corresponding to the to be welded edges of the part such that a folding line is formed along a longitudinal direction forming a bend along each plate; forming a closed structure by stacking the two metal plates on each other vertically after the press forming such that the folding lines form corners that face outwardly and longitudinal edges of the plates contact one another and mutually welding the contacting longitudinal edges along the longitudinal direction so as to form the welded edges; and forming the closed structure into the part having a target shape by guiding and conveying the closed structure with a pair of left and right rotary rolls while changing a distance between the left and right rotary rolls such that the closed structure has a three-dimensional shape and a cross-sectional shape having the folding lines and the welded edges as corners.