| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a metallic double pipe, by which surface pressure is generated in the interface between the external pipe and an internal pipe of the obtained metallic double pipe and adhesiveness is secured. <P>SOLUTION: In this method of manufacturing the metallic double pipe 1, the metallic double pipe 1 is manufactured by bringing the outer surface of the internal pipe 12 into contact with the inner surface of the external pipe 11 by cold drawing where a tapered die 2 is used as a working die. With a condition that the length L (mm) which is calculated by the next formula (1) and in which the external pipe 11 and the internal pipe 12 are brought into contact with each other in the approaching part 2a of the tapered die 2 satisfies the next formula (2), idle drawing is performed. Where, do1 is the outside diameter (mm) of the external pipe 11 before the cold drawing; z is the clearance (mm) between the external pipe 11 and the internal pipe 12 before the cold drawing; d1 is the outside diameter (mm) of the metallic double pipe 1 obtained by the cold drawing; and α is the angle (°) of the approaching part 2a of the tapered die 2. L=(do1-d1-2z)/2sinα (1). 1.35≤1/L≤10 (2). <P>COPYRIGHT: (C)2013,JPO&INPIT |
