The main extruder of plastic extruder is extruder, which is made up of extrusion system, transmission system and heating&cooling system.
1. Extrusion system：
The extrusion system includes a screw, a barrel, a hopper, a handpiece, and a mold. The plastic is plasticized into a uniform melt by an extrusion system, and is continuously extruded by the screw under the pressure established in the process.
(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 and corrosion resistant alloy steel.
(2) barrel
It is a metal cylinder, which is generally made of alloy steel with high heat resistance, high compressive strength, strong wear resistance and corrosion resistance, or composite steel pipe lined with alloy steel. The barrel is matched with the screw to achieve pulverization, softening, melting, plasticizing, venting and compacting of the plastic, and continuously and uniformly conveying the rubber to the molding system. The length of the general barrel is 15 to 30 times its diameter, so that the plastic is fully heated and fully plasticized.
(3) Hopper
A shut-off device is installed at the bottom of the hopper to adjust and cut the flow, and the side of the hopper is provided with a sight hole and a calibration metering device.
(4) Handpiece and mold
The machine head consists of an alloy steel inner sleeve and a carbon steel outer casing, and a molding die is arranged in the machine head. The function of the machine head is to transform the rotating plastic melt into a parallel linear motion, which is evenly and smoothly introduced into the mold sleeve and imparts the necessary molding pressure to the plastic. The plastic is plasticized and compacted in the barrel, and the porous filter plate flows into the head forming mold through the neck of the head through a certain flow path, and the core mold sleeve is properly matched to form an annular gap with a decreasing cross section, so that the plastic melt is in the A continuous dense tubular coating is formed around the core. In order to ensure the plastic flow path in the machine head is reasonable, and eliminate the dead angle of the accumulated plastic, a shunt sleeve is often placed. In order to eliminate the pressure fluctuation during plastic extrusion, a pressure equalizing ring is also provided. A mold correction and adjustment device is also mounted on the handpiece to facilitate adjustment and correction of the concentricity of the core and the mold sleeve.The extruder divides the machine head into a bevel head (120o angle) and a right angle head according to the angle between the flow direction of the head and the center line of the screw. The outer casing of the machine head is fixed on the fuselage by bolts. The mold in the machine head has a core sitting and is fixed to the inlet port of the machine head with a nut. The front of the core seat is equipped with a core, a core and a core holder. The center has a hole for passing the core wire; a pressure equalizing ring is arranged at the front of the machine head for equalizing the pressure; the extrusion molding part is composed of a die sleeve seat and a mold sleeve, and the position of the mold sleeve can be adjusted by the bolt through the support In order to adjust the relative position of the die sleeve to the core, it is convenient to adjust the uniformity of the thickness of the extrusion layer. The outside of the machine head is equipped with a heating device and a temperature measuring device.
