| 摘要 |
PURPOSE:To prevent generation of wrinkles at the inside of a curved part due to buckling when bending a metallic tube smaller in thickness compared with the outer diameter by using a bending die of a specified radius by applying tensile force to the metallic tube in the axial direction. CONSTITUTION:A metallic tube 6 is bent by rotating a clamping die 1, a sliding die 2 and a clamping die 1 clockwise around the center axis of a bending die 3. At this time, the sliding die 2 slides in the axial direction of the tube 6 while fixing the tube 6, and at the same time, a clamp 4 is pressed by a hydraulic cylinder 5 in the direction of the arrow to give circumferential tensile force to the tube 6. Compressive stress generated at the inside of bending of the tube 6 is reduced by this tensile force, and generation of wrinkles at the inside of bending of the tube 6 caused by excessive compressive stress is suppressed. Thus, bending of large curvature becomes possible even when the thickness of the tube is small compared with the diameter. |
