The main machine of plastic pelletizing machine is extruder, which consists of extrusion system, transmission system and heating and cooling system. Vigorously develop renewable resources, turning waste into treasure.
1. extrusion system extrusion system including hopper, head, plastic through the extrusion system and plasticized into a uniform melt, and in the process established under pressure, by the screw continuous extrusion head.
(1) screw: is the most important part of the extruder, it is directly related to the scope of application and productivity of the extruder, made of high-strength corrosion-resistant alloy steel.
(2) barrel: is a metal cylinder, generally made of heat-resistant, high pressure strength, strong wear-resistant, corrosion-resistant alloy steel or alloy steel lined with composite steel pipe. The barrel cooperates with the screw to realize the crushing, softening, melting, plasticizing, exhausting and compacting of the plastic, and continuously and evenly conveying the rubber to the molding system. Generally the length of the barrel is 15~30 times of its diameter, so that the plastic is 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, and the side of the hopper is equipped with a sight hole and a calibrated measuring device.
(4) Head and mold: The head is composed of alloy steel inner sleeve and carbon steel outer sleeve, and the head is equipped with molding mold. The role of the head is to transform the rotating plastic melt into a parallel linear motion, which is evenly and smoothly introduced into the mold sleeve, and give the plastic the necessary molding pressure. The plastic is plasticized and compacted in the barrel of the machine and flows through the neck of the head through a certain flow path through the perforated filter plate into the forming mold of the head, and the mold core and mold sleeve are properly matched to form an annular gap with decreasing cross section, so that the plastic melt forms a continuous dense tubular cladding layer around the core line. In order to ensure that the plastic flow channel in the head is reasonable and to eliminate the dead angle of the accumulated plastic, there is often a diversion sleeve placed, and to eliminate the pressure fluctuation of plastic extrusion, there is also a pressure equalization ring set. The head is also equipped with a die correction and adjustment device, which is convenient for adjusting and correcting the concentricity of the die core and die sleeve.
2. Drive system The drive system is used to drive the screw and supply the torque and speed required by the screw during the extrusion process, usually consisting of an electric motor, reducer and bearings.
3. heating and cooling device Heating and cooling are necessary for the plastic extrusion process to be able to proceed.
(1) 2013 extrusion machine is usually used for electric heating, divided into resistance heating and induction heating, heating sheet installed in the body, neck, head parts. The heating device heats the plastic in the barrel from the outside to warm it up to the temperature required for the process operation.
(2) The cooling device is set up to ensure that the plastic is in the temperature range required for the process. Specifically, it is to exclude the excess heat generated by the shear friction of the rotating screw in order to avoid the plastic from decomposing, scorching or shaping difficulties due to the high temperature. Barrel cooling is divided into two kinds of water-cooled and air-cooled, generally small and medium-sized extrusion machine using air-cooled is more appropriate, large is more water-cooled or a combination of two forms of cooling; screw cooling is mainly used in the center of water-cooled, the purpose is to increase the rate of solid material delivery, stabilize the amount of rubber, while improving product quality; but the cooling at the hopper, one is to strengthen the role of solid material delivery, to prevent the plastic grain sticky blockage because of the heating The second is to ensure the normal work of the transmission part.
Post time: Feb-17-2023