Plastic Extruder Components

The main machine of the plastic extruder is an extruder, which consists of an extrusion system, a transmission system, and a heating and cooling system.
Extrusion system
The extrusion system includes a screw, a barrel, a hopper, a die, and a mold. The plastic is plasticized into a uniform melt through the extrusion system, and is continuously extruded out of the die by the screw under the pressure established in this process.
⑴ Screw: It is the most important component of the extruder. It is directly related to the application range and productivity of the extruder. It is made of high-strength and corrosion-resistant alloy steel.
⑵ Barrel: It is a metal cylinder, generally made of heat-resistant, high-compression strength, strong and wear-resistant, corrosion-resistant alloy steel or a composite steel pipe lined with alloy steel. The barrel cooperates with the screw to realize the crushing, softening, melting, plasticizing, exhausting and compacting of the plastic, and continuously and evenly conveys the rubber material 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 fully plasticized.
⑶ Hopper: A cut-off device is installed at the bottom of the hopper to adjust and cut off the material flow, and a viewing hole and a calibration metering device are installed on the side of the hopper.
⑷ Die and mold: The die is composed of an alloy steel inner sleeve and a carbon steel outer sleeve. A molding mold is installed in the die. The function of the die is to convert the rotating plastic melt into parallel linear motion, evenly and smoothly introduce it into the mold sleeve, and give the plastic the necessary molding pressure. The plastic is plasticized and compacted in the barrel, and flows into the die molding mold through the porous filter plate along a certain flow channel through the die neck. The mold core and the mold sleeve are properly matched to form an annular gap with a continuously decreasing cross-section, so that the plastic melt forms a continuous and dense tubular coating around the core line. In order to ensure the reasonable plastic flow channel in the die and eliminate the dead corners of accumulated plastic, a diversion sleeve is often installed. In order to eliminate pressure fluctuations during plastic extrusion, an equalizing ring is also set. The die is also equipped with a mold correction and adjustment device to facilitate the adjustment and correction of the concentricity of the mold core and the mold sleeve.
According to the angle between the die flow direction and the center line of the screw, the die of the extruder is divided into an angled die (angle 120o) and a right-angle die. The shell of the die is fixed to the body with bolts. The mold inside the die has a core seat and is fixed to the inlet port of the die with a nut. The front of the core seat is equipped with a core. The center of the core and the core seat has a hole for passing the core wire. A pressure equalizing ring is installed at the front of the die to balance the pressure. The extrusion molding part consists of a die sleeve seat and a die sleeve. The position of the die sleeve can be adjusted by bolts through the support to adjust the relative position of the die sleeve to the die core, so as to facilitate the adjustment of the uniformity of the thickness of the extruded layer. The outside of the die is equipped with a heating device and a temperature measuring device.