VEHICLE BODY STRUCTURE MEMBER AND MANUFACTURING METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a vehicle body structure member having a bent part such as a rear fork of a motorcycle and a vehicle body frame of the vehicle in which welding to a bracket at the bent part is carried out with no generation of gap and reduction of strength owing to generation of stress concentration. SOLUTION: A pair of right/left fork bodies 23 constituting the rear fork 12 are formed to a polygonal pipe having the bent part 25 bent so as to outwardly project at a center part 26 by bulging in which an outline of a round pipe is molded by an outer mold while applying a liquid pressure to the inside of the round pipe. A taper part 27 of which a height becomes small toward a rear side is formed on at least the center part 26. Head part members 21 are welded to a part laying from front ends at an inner side surfaces of the fork bodies 23, 23 in the neighborhood of a front side of the bent part 25 and front edges of the fork bodies 23, 23. The bulging can be also utilized for a complex shape having a hollow part and a bent part such as a vehicle body frame.