Extruding three-ply plastic tubing, etc.

摘要

Composite plastic tubes, hollow sections, etc. are extruded where they consist of solid outer and inner layers and a centre core with a different type of structure (e.g. foam). In the process at least the inner solid layer is fed at the front cylindrical part of the extruding tool on to the combined outer layer/core which has been moving there beforehand; the inner layer is there welded on to the i.d. of the core layer; the longitudinal weld seams between the respective layers are offset from each other.