PURPOSE: To produce with high efficiency a bent tube product having no build up of the wall in a welded part, few thermal distortion, a smart and tough design and high quality by cutting a hollow angular tube with the notching angle different on the left and right using a prismatic die and eliminating any gap at a bending and joining part in the case of bending and forming the tube to be notched. ;CONSTITUTION: A notch part S is formed on an arbitrary position with a prismatic die 1, next, a bending part is bent to join like a bending and joining part T, which is just only bent inward with a manual operation or a device in this joining method. The bending and joining part T is rounded like (b) in order to facilitate bending and eliminate not only shrink of the wall due to plasticity by bending into a desired angle but also collision to avoid spring back. The slope angle of blade edge 5 of the prismatic die 1 are specified to be 40.5° and 49.5° by varying the slope angle of blade 5 on the left and right so that the bending and joining part T is completely joined without any gap at part (a).;COPYRIGHT: (C)1996,JPO
展开▼
