Brief introduction of single screw extruder

Single screw extruder is a common extrusion equipment in plastic processing industry. What is its principle and structure? The principle of single screw extruder is analyzed from the conveying section, compression section and metering section of extruder.

Single screw extruder is generally divided into three sections according to the effective length, and the effective length of the three sections is determined according to the diameter, pitch and depth of the screw, which is generally divided into one third.

High-efficiency single-screw extruder adopts two-step integrated design to strengthen plasticizing function and ensure high-speed and high-performance stable extrusion. The comprehensive mixing design of special barrier ensures the mixing effect of materials, and the high shear and low melting plasticizing temperature ensure the high performance, low temperature and low pressure metering extrusion of materials. Design concept and characteristics: high-speed and high-yield extrusion based on high flatness. The last thread of the material port begins to be called the conveying section, where the material is required not to be plasticized, but to be preheated and compacted under pressure. In the past, the old extrusion theory thought that the material here was a loose body, but later it proved that the material here was actually a solid plug, that is to say, the material here was a solid like a plug after being extruded, so it was its function to complete the transportation task.

Principle of single screw extruder: when the second stage is called compression stage, the volume of screw groove decreases gradually from large to small, and the temperature should reach the plasticization degree of materials. The compression generated here is from conveying stage 3 to 1, which is called screw compression ratio -3: 1. Some machines have also changed, and plasticized materials have entered the third stage.

Principle of single screw extruder: The third stage is metering stage, where the materials are kept at plasticizing temperature, and only the molten materials are accurately and quantitatively transported and supplied to the mold like a metering pump. At this time, the temperature should not be lower than the plasticizing temperature, but generally slightly higher.

Single screw extruder is mainly used to extrude soft and hard thermoplastics such as PVC and polyethylene. It can be used to process various plastic products, such as films, pipes, plates, ribbons, etc. , can also be used for granulation.

The plastic extruder has advanced design, high quality, good plasticization and low energy consumption. Involute gear transmission has the characteristics of low noise, stable operation, large bearing capacity and long life. Pipe extrusion: suitable for PP-R pipe, pe gas pipe, PEX cross-linked pipe, aluminum-plastic composite pipe, ABS pipe, PVC pipe, HDPE silicon core pipe and various co-extrusion composite pipes.

Plate extrusion: suitable for extrusion of PVC, PET, PS, PP, PC and other profiles and plates. Extrude other plastics, such as silk, rods, etc.

Profile extrusion: adjusting the speed of extruder and changing the structure of extrusion screw can be suitable for producing various plastic profiles such as PVC and polyolefin. Modified granulation: suitable for blending, modification and enhanced granulation of various plastics.