Hollow profiled structure made from thermoplastic. Method and apparatus for the extrusion of same structure.

摘要

The invention relates to a cavitied profiled structure made from thermoplastic resin, the cavities of which are disposed substantially perpendicularly to the axis of the structure. The structure is produced by means of an extrusion apparatus consisting of an extrusion head (1) and of an extrusion tool (2), the extrusion head being divided into three substantially superposed channels (3)(4)(5) which emerge substantially into the region of the three corresponding channels of the extrusion tool and, on the opposite side, are connected to the feed channel of at least one extruder, the two outer channels (3)(5) serving for the passage of the material constituting the external walls of the structure or of the tube and the intermediate channel (4) serving for the passage of the material for the manufacture of the walls of the cavities, the said apparatus being characterised in that each of the outer channels is separated from the intermediate channel by means of an additional channel (7)(8), ending up, at the output, in alignment with those of the other channels, and the input of which, outside the apparatus, is intended to be connected to a means for varying the pressure. The structure is obtained by creating an alternating pressure variation in the additional channels (7)(8).