| 摘要 |
PCT No. PCT/FI90/00178 Sec. 371 Date Mar. 12, 1992 Sec. 102(e) Date Mar. 12, 1992 PCT Filed Jul. 5, 1990 PCT Pub. No. WO91/00797 PCT Pub. Date Jan. 24, 1991.An apparatus for manufacturing from a mouldable material a pipe having ribs on its outer surface and a smooth inner surface has a core including a shaft, a conically widening mandrel located downstream of the shaft in a direction of production and a kernel having an initial zone and an end zone respectively of substantially uniform diameters successively disposed downstream of the mandrel. An extrusion sleeve surrounds the core and forms with the core a nozzle for the material. The extrusion sleeve has a first end face located upstream of the kernel. Moulds encase the extrusion sleeve and the core, the moulds being movable along endless paths and having grooves on inner surfaces for forming the ribs on the pipe. A heater heats the initial zone of the kernel, the initial zone of the kernel being cylindrical. A first cooler cools the end zone of the kernel. A second end face of an upstream outset of the end zone of the kernel conically widens in the direction of production from a smallest diameter substantially corresponding to the diameter of the initial zone to a largest diameter. |
