What is the extrusion system of a plastic extruder

The extrusion system includes screw, cylinder, hopper, head and die. The plastic of the plastic extruder is plasticized into a uniform melt through the extrusion system, and under the pressure established in this process, the screw is continuously extruded out of the head.

Screw: It is the main component of the extruder, which is directly related to the application range and productivity of the extruder. It is made of high-strength corrosion-resistant alloy steel.

Cylinder: It is a kind of metal cylinder, which is generally made of alloy steel or composite steel pipe lined with alloy steel that is resistant to high temperature, high compressive strength, strong, wear-resistant, and corrosion-resistant. The barrel is matched with the screw to realize the crushing, softening, melting, plasticizing, exhaust and compaction of the plastic, and continuously and uniformly convey the rubber material to the molding system. The length of the ordinary cylinder is 15 to 30 times its diameter, and the principle is to fully heat and plasticize the plastic.

Hopper: There is a cut-off device at the bottom of the hopper to adjust and cut off the material flow. The side of the hopper is equipped with a sight hole and a calibration metering device. 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 convert the rotating plastic melt into parallel linear motion, and introduce it into the mold evenly and stably, giving the plastic the necessary molding pressure. Plastic extruder plastic is plasticized and compacted in the barrel, and flows into the molding die of the die through the head and neck through the porous filter plate along a certain flow path. The die core and die are properly matched to form an annular gap with a decreasing cross-section to make the plastic The melt forms a continuous tight tubular coating around the core wire. In order to ensure that the plastic flow path in the die is reasonable and eliminate the dead corners of the accumulated plastic, a shunt sleeve is often set. In order 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 the concentricity of the mold core and the mold.

The plastic extruder divides the die head into oblique die head (angle 120o) and right angle die head according to the material flow direction of the die head and the angle of the screw centerline. The shell of the machine head is fixed on the fuselage with bolts, the mold in the machine head is seated with a core, and a nut is fixed to the entrance port of the machine head. The core is set in front of the core seat, and the center of the core and the core seat is set. Set the hole, through the core wire, set a pressure equalizing ring at the front of the die to equalize the pressure. The extrusion molding part is composed of the die seat and the die seat. The position of the die seat is adjusted by the bolt support. The mold seat is opposite to the core relative position