method and device for cooling extrudierter hollow sections

摘要

In a process for cooling extruded plastic hollow profiles (8) especially tubes, liquid or over-critical carbon dioxide is passed through an extruder head (5) and decompressed to give gaseous and solid CO2. The gaseous CO2 is directed at the inner wall of the hollow profile (8) while the amount of solid CO2 contacting the inner wall is kept to a minimum to avoid damage to the wall surface. The process equipment is also claimed and comprises a fluid or over-critical CO2 which runs through an extrusion head (5) to the inside of the profile (8) and incorporates a decompression nozzle (10). A diverter (11) opposite the decompression nozzle (10) directs decompressed fluid or over-critical CO2 towards or along the inner wall of the profile (8). A guiding pipe (14) forms a flow chamber with the hollow profile (8) for decompressed CO2 and has openings at both axial ends which ensure that CO2 emerging from the decompression nozzle (10) creates suction inside th e guide pipe in the direction of the nozzle.