| 摘要 |
PURPOSE: A hydroforming tube structure which is provided along with reinforcement structure when fabricating molded article through hydroforming to reduce man-hour, thereby reduce production cost, and a hydroforming method using the hydroforming tube structure are provided. CONSTITUTION: The hydroforming tube structure comprises first tube member(5) which composes a part of the tube and has a certain thickness; second tube member(7) which is connected to one side surface of the first tube member and has the same thickness as the first tube member; and a reinforcement tube member(9) which is connected to a side surface between the first and second tube members and has thickness (t1) greater than that (t2) of the first and second tube members. The hydroforming tube structure comprises first tube member having a certain thickness; and a member which is connected to both side surfaces of the first tube member and has thickness greater than that of the first tube member, wherein welding seams(1a,1b) to which the first and second tube members and reinforcement tube member or the first tube member and reinforcement tube member are connected are arranged in a length direction of tube. The hydroforming method comprises the steps of welding a steel sheet having different thickness between one steel sheet and the other steel sheet; fabricating a cylinder shaped tube after the welding step of the steel sheets having different thickness; and molding the tube by charging the cylindrical tube into hydroforming die and increasing fluid pressure inside the tube after the tube fabrication step. |
