| 摘要 |
Two tubes each have a thread separated into two parts (3a, 3b) by an insertion region comprising an annular tongue (13a, 13b) and a leaf (7b, 7c, 15) adjacent to the relevant tongue and recessed from it. The male tongue has a protruding butt face. The two tongues engage respectively in the opposing two leaves to form an S profile, only as the joint is completely screwed together An Independent claim is included for the production of the above joint, including diametral expansion using an expansion ball with a greater diameter than the internal diameter of the pipe, moved axially through the joint. The first and second tongues are dimensioned so the first tongue seats in the second tongue after expansion with the cylindrical surfaces turned to each other so they are in sealed contact over their whole circumference. Preferred Features: The threads are cylindrical or conical with a maximum conicity of 12.5% and trapedoizal threads .The end of the cylindrical surface of the first tongue is inclined and forms a ramp to facilitate engagement of the first tongue in the second tongue during assembly of the joint. The first tongue butts at the end of screwing on the transverse surface (14) at the bottom of the second tongue, defining the end of the screwing operation. The radial thickness of the first and second tongues are equal and the ratio between the height of each tongue measured axially and its radial thickness is 0.8-1.6, with the height 0.8-3 mm. The joint is expanded radially into the range of plastic deformation, by at least 10%.
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