The mainframe of the plastic granulator is an extruding system consisting of an extrusion system, a transmission-driven system and a heating and cooling system.
1.Extrusion system: It consists of the screw, the barrel, the hopper, the machine head, and the mold. The plastic material is plasticized into a uniform melt through an extrusion system, and continuously squeezed by the screw under the pressure established in the process.
2.The Screw: It is the main component of the extruder. It is directly related to the application range and production efficiency of the extruder. It is made of highly corrosion-resistant alloy steel.
3.The Barrel: It is a metal seamless barrel, which is generally made of alloy steel with high heat-resisting,compresion-resisting,strong wear-resisting and corrosion-resisting or composite steel pipe lined with alloy steel. And the barrel is matched with the screw to achieve pulverization, softening, melting, plasticizing, venting and compacting of the plastic material,and conveying the rubber to the molding system continuously and uniformly.Generally the length of the barrel is 1 out of 18 of its diameter, so that the plastic material could be fully heated and plasticized.
4.The Hopper: The bottom of the hopper is equipped with a cutting device to adjust and cut the flow of the material. And the side of the hopper is equipped with a sight hole and a calibration metering device.
5.The Die Head and the Mold: The die head is made of an alloy steel inner sleeve and a carbon steel jacket within a molding die.
After the plastic material is added to the hopper, the hopper falls smoothly onto the screw,and bitten by the screw thread. As the screw rotates, the thread is forced to advance toward the head to form a mechanical conveying process.And when the plastic material is running from the feeding port to the machine head, a high pressure is formed in the plastic plasticizing process,,due to the gradually reduced thread depth of the screw, and the resistance of the filter screen, the manifold and the head,which makes the material pressed densely,improving its heat conductivity,accelerating the plastic to melt quickly, and gradually increasing the pressure to allow the gas originally existing in the pellets to be discharged from the vent.
While the pressure is rising,on the one hand,the plastic material is heated by the outside. On the other hand, during the movement of compression, shearing and agitation, the plastic material itself generates a large amount of heat due to internal friction. Under the combined action of external force and internal force, The temperature of the plastic matrial is gradually increasing, and its physical state also undergoes a change of the glass state-high elastic state and viscous flow state.