What are the classification types of extruders? Plastic […]
What are the classification types of extruders?
Plastic extruders are divided into twin screw extruders and single screw extruders. The difference between the two extruders:
Single-screw machine and twin-screw machine: one is a screw and the other is two screws. Both are driven by a motor. The power varies with the screw. The power of the 50 cone double is about 20kW, and the 65 cone is about 37kW. The output is related to the material and screw. The output of the 50 cone double is about 100-150kg/h, and the 65 cone double is about 200-280kg/h. The output of a single screw is only half.
According to the number of screws, extruders can be divided into single-screw, twin-screw and multi-screw extruders. Currently, the single screw extruder is the most widely used, suitable for the extrusion processing of general materials. Due to the fact that the twin-screw extruder has less heat generated by friction, the shearing of the material is relatively uniform, the conveying capacity of the screw is large, the extrusion volume is relatively stable, the material stays long in the barrel, and the mixing is uniform.
SJSZ series conical twin-screw extruder has the characteristics of forced extrusion, high quality, wide adaptability, long life, low shear rate, difficult decomposition of materials, good mixing and plasticization performance, direct powder molding, etc., and the temperature is automatically controlled. Vacuum exhaust and other devices. It is suitable for the production of tubes, plates, special-shaped materials and other products.
Single screw extruder occupies an important position as a plasticizing granulating machine or forming processing machine. In recent years, single screw extruder has made great progress. Large-scale pelletizing single screw extruder produced in Germany with a screw diameter of 700mm and an output of 36t/h.
The main symbol of the development of the single screw extruder lies in the development of its key part-the screw. In recent years, people have conducted a lot of theoretical and experimental research on screws, and there have been nearly one hundred types of screws, the common ones are separation type, shear type, barrier type, split type and wave type.
From the perspective of single-screw development, although the single-screw extruder is relatively complete, with the continuous development of polymer materials and plastic products, more characteristic new-type screws and special single-screw extruders will emerge. Generally speaking, the single screw extruder is developing towards high speed, high efficiency and specialization.
The twin-screw extruder has good feeding characteristics and is suitable for powder processing. It has better mixing, exhaust, reaction and self-cleaning functions than the single-screw extruder. It is characterized by processing and blending plastics with poor thermal stability. The material time shows its superiority. In recent years, foreign twin-screw extruders have made great progress. Various forms of twin-screw extruders have been serialized and commercialized, and there are many manufacturers. They are roughly classified as follows:
⑴ According to the relative position of the two axes, there are parallel and conical points;
⑵According to the two screw meshing procedures, there are meshing type and non-meshing type;
⑶ According to the rotation direction of the two screws, there are the same direction and the opposite direction, and there are inward and outward points in the opposite direction;
⑷According to the screw rotation speed, there are high speed and low speed;
⑸According to the structure of screw and barrel, there are integral and combined points.
On the basis of twin-screw extruders, in order to make it easier to process blends with poor thermal stability, some manufacturers have developed multi-screw extruders such as planetary extruders.