| 摘要 |
An extrusion apparatus and method, and a tubular product and a pipe made of several different materials. The extrusion apparatus according to the invention comprises at least one stator (1, 6, 10), at least one rotor (2, 2a, 2b), and at least one annular feed gap (3) situated between the stator (1, 6, 10) and the rotor (2, 2a, 2b). The diameter of the feed gap (3) decreases at least partly continuously in the direction of flow of the plastic material to be extruded, and its diameter also increases continuously at least at a section of its length in the aforementioned direction of flow. With such a construction, the pressure acting on the structure of the extrusion apparatus can be considerably balanced, i.e. the apparatus can be made more durable. The invention also relates to a tubular product and a pipe made of several different materials.
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