Influence of different screw configurations on the flow field of intermeshing co-rotating twin-screw extruder

Abstract

Objective: To explore the influence of different screw configurations of intermeshing co-rotating twin -screw extruder on the flow field and improve the material properties of PLA. Methods: The geometric model of double threaded element was established by using Solidworks software, and the numerical simulation was carried out in Polyflow. The post-processing analysis of the simulation results was carried out with the help of Fieldview software. The shear rate field, pressure field, velocity field, viscosity field and the residence time distribution RTD were compared to obtain the influence of screw groove depth on the flow field. Results: When the center distance was the same, the depth of the screw groove was changed by changing the ratio of the outer diameter to the inner diameter of the threaded element, physical fields and mixing performance had great differences in the flow field of intermeshing co-rotating twin-screw extruder under the same process conditions. Compared with configuration 2, configuration 1 had stronger shear effect, but configuration 2 had better pressure building ability. In the extrusion process, configuration 2 had good axial mixing ability but poor self-cleaning ability, while configuration 1 had poor axial mixing ability and good self-cleaning ability. Conclusion: The change in screw groove depth has certain effects and rules on the mixing performance of the flow field, which can effectively guide the design of threaded element for twin-screw extruder.

Keywords

• twin-screw extruder
• co-rotating meshing
• double threaded element
• numerical simulation
• flow field