Improvements in or relating to extrusion devices for the continuous production of endless foils and strips from thermoplastic material

摘要

PICT:0732782/IV (a)/1 PICT:0732782/IV (a)/2 An extrusion device for the production of foils or strips of thermoplastic material comprises a block 1, Figs. 1 and 2, having a plurality of extrusion bores 3 which are spaced apart in a horizontal direction, Fig. 2 being a sectional plan view. Each bore has an outlet portion 71 which widens horizontally and is constricted vertically, these constrictions being joined end to end to form a single narrow elongated slot 7 extending across all the bores. The slot 7 leads into at least one elongated mixing and pressure-equalizing chamber 8 which is wider vertically than the slot but is constricted at its outlet 9; as shown, there are two such chambers 8 and 10 in series. The thermoplastic material is fed from a hopper 2 into the bores 3 whence it is discharged by pistons 4 through the chambers and out through a nozzle 11. Conduits 13 allow of heating or cooling. In a modification the pistons are replaced by worms.