| 摘要 |
PROBLEM TO BE SOLVED: To obtain sure connected state and to enable those with the same connected state to be manufactured in large numbers. SOLUTION: Inside the coil tip end 13 at one end 12 of a coil spring, there is provided an engaging coil part 15 which is wound in a smaller inner diameter than the coil tip end 13, at the other end 16 of the coil spring, there is provided a tip end engaging part 17 whose outer diameter of the coil at the tip end is nearly the same as the inner diameter of the coil tip end 13, and inside this tip end engaging part 17, there is provided a small diameter wound part 18 storing the engaging coil part at the one end. Into this engaging coil part 15 at the one end 12, the tip end engaging part 17 at the other end 16 is inserted more inside than the engaging coil part 15, with both ends of the coil spring connected to form an annular coil spring ring.
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