| 摘要 |
A method and an apparatus for producing a multilayer plastic pipe. The method comprises producing said multilayer pipe in an extruder (4) with at least one screw for the inner pipe(s) (1), and one screw (5) for the middle layer (3) for conveying and plasticising plastic material prior to forming it as a pipe. Pressurised gas is injected to the plastic material in the plasticisation zone (A) of the screw (5) for the middle layer (3) at a point where the plastic material is already substantially melted, and the gas is mixed with the plastic material and extruded into the cavity formed by the inner pipe(s) (1) and the outer pipe (2). <IMAGE> |
