(1) Introduction of single screw extruder
Single-screw extruders, as the name suggests, have a single screw inside the extruder barrel. Generally, the effective length is divided into three sections, and the effective length of the three sections is determined according to the screw diameter, pitch, and screw depth, and is generally divided according to each accounting for one-third.
The first section: starting from the last thread of the feed port, it is called the conveying section. The material here is not required to be plasticized, but it must be preheated and squeezed. In the past, the old extrusion theory believed that the material here is a loose body. Later, it was proved that the material here is actually a solid plug, which means that the material here is squeezed. The back is a solid as a plug, so as long as it completes the delivery task, it is its function.
(2) Application of single screw extruder
The single-screw extruder is mainly used in the extrusion of pipes, sheets, plates, and profiled materials, and the granulation of some modified materials.
(1) Introduction of twin-screw extruder
The twin-screw extruder includes the following systems. The screw system mainly completes the plasticization and conveying process of the material, which has a great influence on the performance and quality of the finished product.
① Feeding system: including hopper, stirring motor, and feeding motor. It can prevent material accumulation and facilitate its smooth entry into the feed port.
② External heating system: Mainly use the heating rod and cylinder to heat the material efficiently and promote plasticization.
③Cooling system: The heat exchange system composed of heat transfer oil or water is used to reduce the heat of the fuselage, so as to effectively control the temperature of the cylinder.
④ Hydraulic screen changing system: Use replaceable filter screens to intercept impurities, improve the degree of plasticization, and ensure the uniformity and stability of the quality of the output materials.
Application example of twin-screw extruder: glass fiber reinforced, flame retardant granulation (such as PA6, PA66, PET, PBT, PP, PC reinforced flame retardant, etc.), high filler granulation (such as PE, PP filled with 75% CaCO3), heat-sensitive material granulation (such as PVC, XLPE cable material), thick color masterbatch (such as filling 50% toner), anti-static masterbatch, alloy, coloring, low filling blend granulation, cable material granulation ( Such as sheath material, insulating material), XLPE pipe material granulation (such as masterbatch for hot water crosslinking), thermosetting plastic mixing and extrusion (such as phenolic resin, epoxy resin, powder coating), hot melt adhesive, PU reactive extrusion granulation (such as EVA hot melt adhesive, polyurethane), K resin, SBS devolatilization granulation, etc.
Application examples of single screw extruder: suitable for PP-R pipes, PE gas pipes, PEX cross-linked pipes, aluminum-plastic composite pipes, ABS pipes, PVC pipes, HDPE silicon core pipes and various co-extruded composite pipes; suitable for PVC , PET, PS, PP, PC and other profiles and plates, and other plastics such as filaments, rods, etc.; adjusting the speed of the extruder and changing the structure of the extrusion screw can be applied to the production of PVC and polyolefins. And other plastic profiles.
Post time: Jul-20-2023