PURPOSE: To make a bending process applicable even for an extremely thin walled, small diameter tube through a simple aftertreatment, by applying bending work to a metallic tube which is filled up with water and is freezed up.
CONSTITUTION: A tube 3 as a blank material of a metallic O-ring, for example, is made of a stainless steel and is provided with a diameter d= about 1.6mm and a wall thickness t= about 0.15mm; the tube 3 is filled up with water and is freezed up. One end of the tube 3 is rigidly set to a bending jig 1 (diameter D= about 13.2mm), and the jig 1 is rotated in the direction A; while the tube 3 is guided in the direction B, the tube 3 is quickly wound around the outer surface of the jig 1. Hereupon, a light back tension is applied to the tube 3 so as to be regularly wound around the surface of the jig 1, and the rotational speed of the jig 1 is made as high as possible to prevent the ice freezed up in the tube 3 from melting. This rotational speed may be about 30W360r.p.m. Moreover, this bending process is desirably carried out in a low temperature tank or in an atmosphere of a liquefied gas.
MAEDA NORIJI
AKIMURA HIYOUE
