To provide a manufacturing method for preventing defective forming by positively changing the direction of flow of a material in the vicinity of a projected part when performing hydroforming of a branch projecting system.
This method is a manufacturing method of the hydroformed parts having a projected shape and a material 1 is made to flow in the direction of the projected part 13 by making parts 51 of inside surface parts 11, 21 of dies 10, 20 movable along the surface of the material 1 and by the movement of the inside surface part 51 of this movable inside surface part 51 of the die. Preferably, the base stock of the material 1 in the vicinity of the projected parts 13 is made to flow toward the projected part 13 by moving the inside surface 51 along the material 1 by high pressure which is generated at the working by composing ring members 50 having approximately cylindrical main body independently of the dies 10, 20 freely rotatably. However, the material 1 may be forcedly made to flow by separately providing the moving means of the ring members 50.
Toshio Nakamura
Miyazaki Yoshio
Kaoru Onozuka
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