EXTRUDER FOR PROCESSING OF THERMOPLASTIC MATERIALS Russian patent published in 2003 - IPC

FIELD: processing of thermoplastic materials; applicable in industries using extrusion processes. SUBSTANCE: extruder has body, sleeve with helical channels over its internal surface, stock screw, profiling head and charging hopper. Sleeve in installed body and supported in rolling bearings. Sleeve is rotated relative to its with help of additional drive by means of gear transmission. Sleeve inner diameter is reducing step-by-step in direction of product advance. Inner surface of sleeve has different configuration in each successively arranged extruder zones of charging, mixing, homogenization and metering. Mixing zone includes two successively located sections. At the first section of large diameter, sleeve has helical channel with left- hand thread of constant pitch and depth. At the second section with small diameter, sleeve has smooth cylindrical surface. Homogenization zone consists of section with pins and section with cut gear of fine pitch for planetary gearing. Pins are staggered and directed at acute angle β to axial line. In metering zone, sleeve also has two sections. Located on the first section is left-hand seven thread of constant pitch and depth, and the second section is made with smooth cylindrical surface. Stock screw is also of step configuration. In mixing zone, at the first section of large diameter, pins are staggered at acute angle β to axial line and directed to same side with helical channels of sleeve, at same section , on its internal surface. Pin thickness is equal to thickness of stock screw flight in charging zone. At the second section of small diameter, stock screw has screw thread with constant pitch. Core diameter of this section reduces towards female core. In zone of homogenization, stock screw initial section present gear cutting in form of herring-bone gear of fine [pitch, and next in turn is section of planetary gearing. This section consists of gear cutting of sleeve and stock screw, six satellite glass thrusting the hub of stock screw core and secured in annular holder. Located in beginning of metering zone is polyhedron followed by stock screw section with constant pitch and depth of gear cutting which are smaller than in zones of charging and mixing. Stock screw and sleeve are rotating in different sides. EFFECT: higher quality of product processing due to intensification of effect of compressing forces cousing multiple shear deformations of extrudate melt and extended technological potentialities of extruder. 6 dwg