Extrusion is a method by which materials are continuously passed through a mold in a flow state by heating and pressurizing them in a sheet extrusion line. Compared with other forming methods, it has the advantages of high efficiency and low unit cost. Extrusion is mainly used for the molding of thermoplastic plastics, and can also be used for some thermosetting plastics. All extruded products are continuous profiles, such as pipes, rods, wires, sheets, films, wire and cable coatings, etc. In addition, it can also be used for plastic mixing, plasticizing, granulation, coloring and blending. The products of extrusion can be called "profiles", and because the cross-sectional shape is mostly irregular, it is also called "profiles". After more than 100 years of development, sheet extrusion lines have developed from single screw to twin screw, multi-screw, and even screw-less. Plastic extruders can be matched with various plastic forming auxiliary machines, such as pipes, films, clamping materials, monofilaments, flat filaments, packing belts, extruded nets, plates (sheets), profiles, granules, cable coating, etc. To form various plastic extrusion forming production lines and produce various plastic products. Therefore, sheet extrusion lines are one of the widely used machines in the plastic processing industry now or in the future.
When the sheet extrusion line is in operation, it can naturally provide perfect protection for the extruder. It has many protection functions such as overcurrent, overvoltage, undervoltage, overload, etc., which can provide stable and reliable application conditions for the entire operation system. In fact, its main engine is an extruder. The plastic is plasticized into a uniform melt by the kneading system, and the extrusion head is connected through a screw under the set process pressure. The die head is provided with a steel head, which consists of a plastic die head and a plastic sleeve. In addition, the sheet extrusion line plasticizes and compacts in the cylinder, and flows into the mold through a porous filter plate along a specific channel through the head and neck. The core and cavity match well. In this case, the sheet extrusion line will naturally form an annular space with a reduced cross-section, so that the plastic melt can form a continuous and dense tubular coating around the core wire. Therefore, the main thing now is to ensure that the plastic flow path in the mold is reasonable and eliminate the dead corners of plastic accumulation. Usually, a diverting sleeve is set up. In order to eliminate the pressure fluctuation during the plastic extrusion process, the die head with the equal pressure ring is also equipped with a mold calibration and adjustment device to facilitate the adjustment of the concentricity of the core and cavity. According to the angle between the material flow direction and the screw baseline, the extruder is divided into oblique head parts.