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What are the structural characteristics of the twin-screw extruder?

Update:13 Dec 2018
Summary:

(1) Meshing type co-rotating twin-screw extruder: Since […]

(1) Meshing type co-rotating twin-screw extruder: Since the speed of the co-rotating twin-screw at the meshing position is opposite, one screw pulls the material into the meshing gap, and the other screw pushes the material out of the gap. As a result, the material is transferred from one screw to the other and advances in a "∞" shape. Since the gap of the meshing zone is small, the speed of the meshing screw and the groove are opposite in direction, so that the cutting speed is high, and the self-cleaning effect is good, that is, any accumulated material adhering to the screw can be scraped off, thereby The residence time of the material is very short, so the meshing type co-rotating twin-screw extruder is mainly used for mixing and granulation.

(2) Meshing type counter-rotating twin-screw extruder In the meshing counter-rotating twin-screw extruder, the two screws are symmetrical, and the spiraling of the material on one screw is another due to the different directions of rotation. The screw of the root screw is blocked and cannot form a "∞" type movement. In the solids transport section, the material is transported forward in the form of an approximately closed "C" shaped chamber. However, in the design, a certain amount of clearance is left between the outer diameter of one screw and the root diameter of the other screw, so that the material can pass through. When the material passes through the radial gap between the two screws, it is strongly sheared. Stirring and calendering, so the material is better plasticized, and at the same time it gradually reduces the pitch to obtain the compression ratio, which is mostly used for processing products.