EXTRUSION HEAD WITH RING-SHAPED EXTRUSION CHANNEL AND A PLASTIC TUBE WITH LONG-WINDING HOLLOW CHANNELS OBTAINED IN THE WALL USING SUCH EXTRUSION HEAD.

摘要

Method and extruder for manufacturing plastic pipes provided with longitudinal channels in its wall. Before the extrusion nozzle of the extruder, the stream of plastics to be extruded for forming the pipe is subdivided into two concentric annular streams flowing through two annular division channels formed by means of a dividing member being retained by only a breaker in the outer division channel, the other division channel forming a free passage between the channel inlet and the outlet.