| 摘要 |
PURPOSE:To provide a composite tube which has excellent watertightness and water transportation characteristics and the enlarged part of which is formed uniformly and precisely, by a method wherein a synthetic resin inner tube is held together with an outer tube with blocking pieces and a holding piece and the synthetic resin inner tube part facing to the inner surface of an enlarged socket is gradually expanded with an inner tube expander so as to closely contact with the outer tube. CONSTITUTION:Firstly, a synthetic resin inner tube 4 is inserted in an outer tube 1. Secondly, both ends of the tube 4 are blockedly held with blocking pieces 5 and 8 and a holding piece 7. Thirdly, heating fluid such as steam is poured in the synthetic resin inner tube 4 through an inlet 6 and discharged through an outlet 9 so as to heat, soften and expand said synthetic resin inner tube and at the same time to expand rollers 14 in order to abut against the inner surface of the synthetic resin inner tube by pivoting the rotating shaft 12 of an inner tube expander 10 in such a manner as to assist the expansion of the abutted synthetic resin inner tube part and at the same time to forcibly bring said part into close contact with the inner surface of the enlarged socket 2 of the outer tube. After the synthetic resin inner tube 4 closely contacts with the outer tube 1, the synthetic resin inner tube is solidified by forced cooling or natural cooling. |
