The extrusion system consists of a screw, a barrel, a hopper, a head, and a mold. The plastic is plasticized into a uniform melt by an extrusion system, and under the pressure established in the process, the screw is continuously extruded by the head.
(1) Screw: It is the most important part of the extruder. It is directly related to the application range and productivity of the extruder. It is made of high-strength, corrosion-resistant alloy steel.
(2) Barrel: It is a metal cylinder, generally made of composite steel pipe with high heat resistance, high compressive strength, strong wear-resisting, corrosion-resistant alloy steel or inner alloy steel. The barrel and the screw cooperate to realize the pulverization, softening, melting, plasticizing, exhausting and compacting of the plastic, and continuously and uniformly conveying the rubber material to the forming system. The length of the general barrel is 15 to 30 times of its diameter. Plastics are fully heated and fully plasticized.
(3) Hopper: The bottom of the hopper is equipped with a cut-off device to adjust and cut off the material flow. The side of the hopper is equipped with a sight hole and a calibration metering device.
(4) Head and die: The nose is composed of an inner shell of an alloy steel and a jacket of carbon steel. The head is equipped with a molding die. The function of the head is to convert the rotating plastic melt into parallel linear motion, which is even and stable. Into the mold set, and to give the plastic with the necessary molding pressure, the plastic in the barrel plasticized and compacted, through the porous filter plate along the head through the head neck into the head molding die, the mold core mold fit, An annular gap with decreasing cross-section is formed so that the plastic melt forms a continuous dense tubular coating around the core wire. In order to ensure that the plastic flow path in the head is reasonable and the dead corner of the accumulated plastic is eliminated, a diverter sleeve is often installed. In order to eliminate pressure fluctuations when the plastic is extruded, a pressure equalizing ring is also provided. The head is also equipped with mold correction and adjustment device to facilitate adjustment and correction of the concentricity of the mold core and mold sleeve. In the front of the head is equipped with a pressure equalizing ring for equalizing the pressure; the extrusion molding part is composed of a mold housing and a mold sleeve. The position of the mold sleeve can be adjusted by the bolt through the support to adjust the relative position of the mold sleeve to the core. It is easy to adjust the thickness of the extruded layer. The outside of the nose is equipped with a heating device and a temperature measuring device.