JPS57165140A - Production for double-ply pipe - Google Patents

Abstract

PURPOSE:To produce a double-ply pipe where both pipes are fitted to each other in a high degree, by pressing a closed inside pipe into a closed outside pipe, which is expanded by a liquid pressure, from one end of this outside pipe through a seal guide and releasing the liquid pressure after expanding the outside pipe and contracting the inside pipe simultaneously. CONSTITUTION:The front part of an inside pipe 25 which is closed by a rear closing cover 26 and a small-diameter front closing cover 27 is inserted to a guide hole 9 of a seal guide 10, and the closed state is held in the end of an outside pipe 12. Under this state, pressurized water 20 is supplied and filled up in the space, which is formed by inside and outside pipes 12 and 25 and closing covers 6 and 10, by a pump 18. A hydraulic jack 17 is operated to apply pipe expanding force F and pipe contracting force f to the outside pipe 12 and the inside pipe 25 respectively, and a motor 23 is driven to press the inside pipe 25 into the outside pipe 12 together with the rear cover 26. Next, a cross electromagnetic valve 14 is opened to discharge water having pipe expanding and contracting pressure, and thus, the outside pipe 12 is contracted and the inside pipe 25 is expanded to fix both pipes tightly through a margin to fix surely and strongly.