| 摘要 |
PROBLEM TO BE SOLVED: To secure sufficient air tightness, joining strength, reliability under a heated environment in caulking the joining of metal tubes each other. SOLUTION: The end part of a metal tube 72 covers the end part of a metal tube 70, and in its inside, a wind-up part 73a is brought into contact with a turn-back part 71, and the turn-back part 71 is held with a transition part 74 of the metal tube 72 and the wind-up part 73a. Further, the turn-back part 71 is flattened by receiving the working force in the direction squeezing up/ down. When joining in this way, both metal tubes 70, 72 are brought into contact with each other at the turn-back part 71 of one side metal tube 70 and the wind-up part 73a of the other side metal tube 72, further, the outside of the contact part is covered with an expanded part 73, the holding force is extremely large and also the joining strength is extremely strong.
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