| 摘要 |
PROBLEM TO BE SOLVED: To cover a part of a contact coil which is deteriorated by influence of heat in welding with a connecting ring to be effectively protected, and to reduce the length of a hard part produced by installing the connecting ring by fitting two tight contact coils mutually connected to a connecting ring where a through hole is formed in the peripheral drum part, and performing spot welding after confirmation on a joint part of both tight contact coils through a through hole. SOLUTION: Tight contact coils 20a, 20b forming a flexible shaft 20 are inserted in a connecting ring 21, and joined to each other in such a manner that the end parts of the tight contact coils 20a, 20b closely adhere to each other. A through hole for confirming the joining state and the joining position from the outside is bored in the connecting ring 21, and after such confirmation through the through hole 22 is performed, spot welding is applied to the joining part between the contact coils 20a, 20b by a laser welding device 23. Thus, the joining part between the connecting ring 21 and the contact coils 20a, 20b is welded. |
