Apparatus for non-mechanical die lip temperature adjustment in an extruder

摘要

Apparatus for extruding thermoplastic material includes an extruder having inner and outer die lips adjacent an outlet end of the extruder for transporting an annular stream of thermoplastic material therethrough. The outer die lips are divided into a plurality of circumferential sectors. Each sector includes a passage for circulating heated oil for controlling the viscosity of the thermoplastic material being extruded. The temperature and flow of the heated oil flowing through each sector may be varied according to the required thickness of the product being extruded adjacent that sector. A ring-shaped channel carries the heated oil around the die lips for circulation into the individual sectors.