| 摘要 |
A uniform unevenness is provided on the inner circumferential surface of a pipe element tube (23) by manufacturing the pipe element tube (23) using a manufacturing process that comprises a process (S1-1) of obtaining the pipe element tube (23) by rolling a stainless steel plate material (21) and welding the abutting parts, a plug drawing process (S1-2) of reducing the diameter and adjusting the thickness of the pipe element tube (23) using a mandrel (24), and a tube drawing process (S1-3) of reducing the diameter and adjusting the external form of the pipe element tube (23) without using a mandrel, and by adjusting the number of repetitions of the plug drawing process (S1-2) and the tube drawing process (S1-3). Then the pipe (12), which is obtained by cutting the pipe element tube (23) and has a ring-shaped cross-section, is joined to wire (11), which has a circular cross-section, (S2). |
