| 摘要 |
<p>A bending method for pipe material using a conventional device such as press device, wherein, in order to prevent wall thinning and cracks, one side of a cylindrical pipe material (1) is firmly held by a first clamp (2) with the other side loosely held by a second clamp (3). The clamp (2) is moved downward in the drawing with respect to the clamp (3), with an axially pressing force applied to the pipe material (1) at the opposite ends thereof. The pipe material (1) is plastic-deformed by being guided by a 1/4 spherical surface (4a) of a core (4) and a 1/4 spherical surface (5a) of a core (5) to form linear portions at two bending portions and at an intermediate portion therebetween.</p> |
