| 摘要 |
PROBLEM TO BE SOLVED: To shorten a joint part and to reduce the pull-out force acting on a stop ring, when the pull-out force acts on the joint part to engage a lock ring with the sop ring. SOLUTION: The joint part includes a fitting groove 3 for the lock ring, formed in a socket 1 and tapered toward the opening of the socket 1, a diameter-reduceable and expansible lock ring 4 to fit into the fitting groove 3, whose surface is inclined at the same angle as that of the fitting groove 3, and a stop ring 5 fixed on the external surface of an end of an insertion port 2 inserted into the socket 1. In the pipe joint structure, where the lock ring 4 and the stop ring 5 are engaged, when pulling force acts on the joint part; and the fitting groove 3 is formed into two steps, that is, a large-diameter part 3A and a small-diameter part 3B. The large-diameter part 3A is formed at the end of the insertion port 2 side, and the small-diameter part 3B is formed on the opening side, extending continuously from the large-diameter part 3A. In the large diameter part 3A, the lock ring 4 has an expansible diameter, so that the stop ring 5 can pass through the lock ring 4, when pipes are joined. The small diameter part 3B has an outside diameter corresponding to that of the lock ring 4, when it is reduced.
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