| In order to improve the mixing performance of a single-screw extruder, a new screw assembled with an embedded cycloidal gear reducer and reverse thread was designed. Solid works software was used for modeling and ANSYS/CFX software was used to analyze the change of three dimensional flow field in the flow channel of the new coaxial variable-speed single-screw extruder, and to explore the shear and mixing of the material in its flow channel according to the change of pressure, velocity vector, and cross sectional velocity in the flow channel. The results showed that in the same external situation, the new screw pressure building capacity was weaker than the traditional screw, i.e., the extrusion efficiency of the new screw was lower. Because of the assembly of embedded cycloidal gear reducer, the speed of the new single-screw extruder in its mixing region decreased to 1/6 of the conventional screw, causing material convection, accelerating the pressure field changes, so that the speed of the flow more chaotic. Because of the assembly of the reverse thread, the reverse pressure building capacity appeared in the mixing region, under which the material appeared to reverse the speed of the phenomenon of reflux. In summary, the cycloidal gear reducer and reverse thread can prolong the residence time of the material in the flow channel, increase the number of the extrusion and shear of material, thus enhancing the mixing and distribution capacity, and the extrusion and shear effect of the extruder. |
