What is a single screw extrusion system

The main function of the extrusion system is to melt and plasticize the polymer material to form a uniform melt, and realize the transition from a glass state to a viscous flow state. And in this process, a certain pressure is established, and the screw is continuously extruded and conveyed to the die. Therefore, the extrusion system plays an important role in the molding quality and output of the extrusion process. The extrusion system mainly includes the feeding device, the screw and the barrel. It is the most critical part of the extruder. The screw is the heart of the extruder. The material can only move in the barrel through the rotation of the screw, and is pressurized and compressed. some heat.

The transmission system is usually composed of a motor, a reducer and a bearing, etc. Its main function is to drive the screw and supply the torque and torque required by the screw during the extrusion process. In the extrusion process, the screw speed is required to be stable and not change with the change of screw load to ensure uniform product quality. However, in different occasions, the screw is required to be able to achieve variable speed, so that one equipment can adapt to the requirements of extruding different materials or products of different shapes. In most extruders, the change of screw speed is achieved by adjusting the speed of the motor, and the transmission system is also equipped with a good lubrication system and a rapid braking device.

The heating and cooling system of the extruder consists of a heating device and a cooling device. It is a necessary condition for the extrusion process to proceed smoothly. The heating device and the cooling device must ensure that the melting and plasticizing of the polymer material and the temperature conditions during the molding process meet the technological requirements. The cooling device is generally arranged in the extruder barrel, screw and the bottom of the hopper and other parts. Barrel cooling can be water-cooled or air-cooled. Generally, small and medium-sized extruders mostly use air-cooling; large-scale extruders mostly use water-cooling or a combination of the two.

The single screw barrel cooling mainly adopts central water cooling, the purpose is to increase the solid conveying rate of the material, stabilize the output, and at the same time improve the product quality. The cooling device at the bottom of the hopper is mainly to strengthen the conveying effect of solid materials, and prevent the material particles from sticking due to temperature rise, blocking the material opening and affecting the feeding. Generally, for extruders and high-speed extruders with a screw diameter of more than 90mm, a cooling device must be installed at the bottom of the hopper.