The basic structure of single screw extruder

single screw extruderThe basic structure includes 6 parts: transmission, feeding device, tube, screw, head and die, temperature control device, etc.

The gear is the part that drives the screw to rotate and is usually composed of a motor, a reduction mechanism and bearings.

The lobster device can be divided into gravity feeding and forced feeding according to the lobster method. The hopper is generally cylindrical, conical, etc., and the hopper is equipped with permanent oil interception, residue removal, drying, preheating devices, etc.

The tube is one of the main parts of the extruder. The plasticization and pressure of the material are in progress. The pressure reaches 30 ~ 50MPA and the temperature reaches 150~410. Therefore, it can be considered that the tube needs heat, pressure vessel, strength, wear resistance and corrosion. The general pipe consists of a steel sleeve and an alloy steel lining,

The section of the supply section extending forward from the material inlet is called the supply section. In the supply section, the material is still solid. The main function is to compress the material and the heat moves forward. The screw groove is generally equidistant depth.

The melt section is the middle part of the screw, in which the material is heated, compressed and melted, and discharged at the same time.

The homogenization section is the rear section of the screw. The homogenization section is used to plasticize the melt more uniformly, quantifying the static pressure of uniform extrusion from the head runner. This groove section is constant, but the groove depth is very shallow.

The head and the mold are generally a whole, the head is the transition part between the mold and the tube, and the mold is the molding part of the product cross section. The function of the head is to convert the polymer melt in the rotating motion into parallel linear motion, so that the material is more evenly plasticized and the melt is evenly three-dimensional. In addition, it can also give the necessary molding pressure, so that the material is easy to shape, and the product is compact.

The temperature control device includes a heating device, a cooling device, and a temperature measurement and control device. Heating devices generally have heat carrier heating, resistance heating, inductive heating and infrared heating. The cooling device generally has air cooling, water cooling and oil cooling. Temperature measurement generally measures thermocouples, resistance thermometers and thermistors. Control devices typically use manual control, bit adjustment, time scaling, and PID adjustment.

Composition and Assembly Process of Single Screw Extruder

Single screw extruder is a typical extruder equipment, which is widely used in plastic processing industry. It is mainly used for the production and manufacture of PP-R pipe, PE natural gas pipe, PEX cross pipe, aluminum plastic composite pipe, ABS pipe, PVC pipe, HDPE silicon core pipe and various cavity extrusion composite pipes. The principle of single screw extruder is analyzed.

single screw extruderGenerally, the effective length is divided into three sections. The screw diameter, pitch and screw depth determine the three effective lengths, which are generally divided into 1/3.

The first segment: Starting from the latter threaded segment of the entrance, it is called the conveyor segment. The material here is required not to be plasticized, but to be preheated and pressed. In the past, the old extrusion theory believed that this material was loose, but later it was proved that this material was actually a solid plug, which meant that the solid was equal to the plug after the material was extruded, so it was its function to complete the transportation task.

The second section is called the compression section. The volume of the spiral groove in this section should be greatly reduced, and the temperature should reach the degree of plasticization of the material. Compression occurs (from conveyor belt section 3 to 1, screw compression ratio 33543:1, some machines are also different), and the plasticized material enters the third section.

The third paragraph: measurement section. Here the material to maintain the plasticizing temperature, but like a quantitative pump to accurately and quantitatively convey the melt material to supply the head, at this time the temperature can not be lower than the plasticizing temperature, generally slightly higher.