PURPOSE: To improve dimensional accuracy of bending by placing the plate to be formed on a rigid die provided with a V-formed surface, performing the rolling reduction for the plate to be formed from the upside to the V-formed surface by an elastic punch having a plane or projecting surface on its lower end plane.
CONSTITUTION: On the die 1 having the V-formed surface 4 and made of a rigid member, the laminate steel plate 3 to be formed is placed. Then, the punch 2 consisting of the elastic member and forming the plane or the projecting plane having larger front end angle than the inner angle of the formed plane is disposed. The punch 2 is directed to the V-formed plane 4 of the die 1 to start the rolling reduction, the steel plate 3 is bent uniformly and with a slow curvature into the formed plane 4 by the lower end face of the punch 2. At this time, the punch 2 having elasticity is deformed, the steel plate 3 is pressed on the both side faces of the formed plane 4 to be restricted to form. Because receiving the isotropic pressure forming, the generating of the gull phenomenon of the steel plate 3 is prevented to improve the bending dimensional accuracy.
KOBAYASHI AKIRA
YUZUTORI YOSHIYUKI
