Extrusion die with sprays for internal cooling - to increase and control the rate of cooling throughout the multichannel hollow profiles

摘要

A die for extrusion of a multi-channel hollow profile is fitted with tubes which project from each core mandrel to provide a coolant spray withing each channel of the profile. The coolant jets are supplied with a mixt. of air and water by drawing water from a reservoir via a venturi jet. Pref. the reservoir is pressurised by a branch from air supply line. The example system has individual manifold pipes made of heat-resistant plastic material mounted within sleeves made of PTFE. The spray is released from nozzles on the end of each tube. Direct cooling of each internal wall surface can be used to control or balance the rate of freezing/crystallisation or the extent of stress relief in different parts of the profile section. Minimises the length of the cooling system required to chill the extrudate.