MANUFACTURE OF BENT PIPE

PURPOSE:To manufacture the pipe in which the diameter of a bent pipe, its longitudinal cross section shape and its bent radius, etc., are arbitrary by leading fluid pressure into a non-press-contacting part of a clad sheet and forming a tubular bulge part, and cutting out the bulge part from the clad sheet. CONSTITUTION:On one face of one metallic plate of two pieces of metallic plates, a press-contacting inhibitor is printed in a pattern corresponding to a shape of a bent pipe 12 to be manufactured. By pressing the other metallic plate against the printing surface of its metallic plate, a clad sheet 1 having plural bent pipe forming use non-press-contacting parts 2 and a liquid pressure leading-in use non-press-contacting part 3 is formed. Subsequently, by leading in fluid pressure such as air pressure, etc., from the fluid pressure leading-in use press-contacting part 3 of this clad sheet 1, and bringing all press-contacting parts 2-6 to tube expansion, a snaked tubular bulge part 8 is formed, and the clad sheet 1 is cut into a necessary shape. Thereafter, from both the cut clad sheets, a snaked tube is cut out. Moreover, by bringing its snaked tube to regular tube expansion in a die, a snaked tube 11 having a bent tube 9 and a communicating tube part 10 is formed, and in the end, by cutting and removing the communicating tube part 10 of the snaked tube 11, a bent tube 12 is obtained.