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Mechanical principle of extruder screw barrel

Update:01 Nov 2018
Summary:

Water or a suitable liquid is added to the raw material […]

Water or a suitable liquid is added to the raw material powder and continuously stirred. The agitated material is extruded from a porous head or metal mesh at a high extrusion pressure.
Usually, after the material is placed in a cylindrical container, the material is extruded with a screw. After using the variable frequency technology, the pressure can be controlled so that the most suitable linear speed can be selected.
Single screw extruder principle
The single screw is generally divided into three sections in the effective length. The effective length of the three sections is determined according to the screw diameter and the pitch. The effective length is generally divided into one third.
The last thread of the material port is called the conveying section: the material is required to be plasticized here, but it must be preheated and compacted. In the past, the old extrusion theory believed that the material here was loose, and later proved that the material here is actually The solid plug, that is to say, the material here is a solid like a plug after being squeezed, so it is its function as long as the conveying task is completed.
The second section is called the compression section. At this time, the volume of the groove is gradually reduced from large to large, and the temperature is to reach the plasticizing degree of the material. Here, the compression is generated by the conveying section three, where it is compressed to one, which is called the compression ratio of the screw -- 3:1, some machines have also changed, and the finished plasticized material enters the third stage.
The third section is the metering section, where the material maintains the plasticizing temperature, just as accurately and quantitatively transports the melt material as the metering pump to supply the head. At this time, the temperature cannot be lower than the plasticizing temperature, generally slightly higher.