EXTRUDER FOR PROCESSING THERMOPLASTIC MATERIALS Russian patent published in 1998 - IPC

FIELD: processing thermoplastic materials requiring continuous mixing and homogenizing. SUBSTANCE: extruder has case, hopper, screw, and shaping head with drawing die. Shape and configuration of inner surface of case vary to form six regions arranged in tandem and gradually turning one into other over helical line. Shape of inner surface of case varies in each region depending on its function. In charging region, case has constant inner nominal diameter. In mixing region, inner surface of case has rectangular slot made along helical line, its depth and pitch being constant throughout entire length of region. In compression region, case inner diameter varies and diametric clearance between screw and case reduces from region origin to its end. In homogenizing region, permanent-pitch and permanent-depth slot is made on inner surface of case to form oval helical duct opposing direction of screw thread. In gradual pressure rise region, clearance between outer diameter of screw and inner diameter of case reduces in direction of material flow. In pressure stabilization region, inner surface of nominal-diameter case is provided with slot forming varying-depth conical helical duct. Flow section of helical duct increases in direction of product flow in proportion to pressure rise. EFFECT: improved quality of finished product due to intensification of mixing and homogenizing processes as well as due to presetting rate of pressure rise. 4 dwg