| 摘要 |
PROBLEM TO BE SOLVED: To control the decrease of mechanical strength by a method in which a laminated pipe in which an intermediate layer of a foamed thermoplastic resin is formed on the outside of an inner layer pipe of the non-foamed resin, and an outer layer pipe of the non-foamed resin is formed on the outside of the intermediate layer is expanded at a temperature higher than the softening point of each layer. SOLUTION: An inner layer pipe is formed by an extruder 1, and an intermediate layer and an outer layer pipe are laminated on the inner layer pipe. The produced laminated pipe 11, after being solidified by a cooling bath 3, is supplied to a receiving machine 4 and stretched in the axial direction by an endless belt 42. The stretched laminated pipe 11 is heated at the softening point of each layer by a heating device 5 and supplied to an expanding device 6. The device 6 has a torpedo 10 spreader 10 and expands the laminated pipe 11 to produce a multi-layer pipe 12, Next, the multi-layer pipe 12, after being cooled by a cooling bath 7, is supplied to a receiving machine 8. received by an endless belt 82, and cut in a prescribed size by a cutter 9 into a product. |
