The main engine of the plastic extruder is the extruder, which consists of an extrusion system, a transmission system and a heating and cooling system.
1. The extrusion system includes screw, barrel, hopper, head, and die. The plastic is plasticized into a uniform melt through the extrusion system, and under the pressure created in this link, it is continuously extruded by the screw. head.
(1) Screw: It is the most critical component of the extruder. It directly affects the application range and production efficiency of the extruder. It is made of high-strength corrosion-resistant alloy steel.
(2) Cylinder: It is a metal cylinder, usually made of alloy steel with high temperature resistance, high compressive strength, sturdy, wear-resistant, and corrosion-resistant alloy steel or composite copper pipe lined with alloy steel. The barrel and the screw cooperate with each other to complete the crushing, softening, melting, plasticizing, exhaust and compaction of the plastic, and continuously and uniformly transport the rubber to the molding system. Generally, the length of the barrel is 15 to 30 times its diameter, so that the plastic can be fully heated and plasticized as the criterion.
(3) Hopper: The bottom of the hopper is equipped with a cutting device, which is convenient for adjusting and cutting off the material flow. The side of the hopper is equipped with a sight hole and a marking metering device.
(4) Machine head and mold: The machine head is composed of an alloy steel inner sleeve and a carbon steel outer sleeve, and the machine head is equipped with a forming mold. The function of the machine head is to transform the rotating plastic melt into parallel linear motion, introduce it into the mold sleeve evenly and smoothly, and give the plastic necessary molding pressure. The plastic is plasticized and compacted in the barrel, and injected into the molding die of the die through the neck of the die through the porous filter plate along the corresponding flow path. The core and die sleeves are properly matched with each other to form an annular gap with a continuous reduction in cross-section, so that the plastic melts. A continuous and dense tubular coating layer is formed around the core wire. In order to ensure the plastic flow path in the machine head is reasonable and to remove the dead corners of the accumulated plastic, a shunt sleeve is usually installed. To eliminate pressure fluctuations during plastic extrusion, a pressure equalizing ring is also set. The machine head is also equipped with a mold correction and adjustment device, which is convenient to adjust and correct the concentricity of the mold core and the mold sleeve.
