Vairable length thermoplastic extrusion continuous prodn. with single mould - by introducing from heated nozzle in cooled tube contg. partition moved by material flow, and cooling on mould external wall

摘要

The prodn. comprises intrusion and inserting a partition into the melt between the extruder and the mould to move the partition with the melt flow; and the intrusion in front of the partition is released from the mould and ejected by the pressure of the intrusion pressure of the next shot, the product is cooled further outside the mould. The melt is pref. discharged from the extruder through the heated nozzle into the cooled mould to solidify on the mould wall. As more extruded melt advances it builds up. A partition is inserted into the tool bore and moves forwards with the melt. As a result the pressure increases on the cooled material which is moved along accordingly. Continuing melt flow pref. presses the earlier material through the cooling stage. The tool to insert the partitions has two holes to feed fresh partitions in from a magazine. The length of prod. is controlled by processing time at a constant rate of extrusion, or, pref. by sensing magnetically the movement of the partition. ADVANTAGE - The prodn. uses only one single mould. The extrusion procedure is uninterrupted. The filling pressure may be adjusted.