Influence of different slip conditions on the extruding process of PLA in counter⁃rotating twin screw

doi:10.19491/j.issn.1001-9278.2024.12.018

Abstract

Abstract:

End curve is deduced and built in the method of relative motion for the 3 d model， after its meshing in Gambit software into the finite element simulation software Ansys， through the simulation process of motion are set up different slip boundary conditions to simulate the material in barrel inner surface and the screw on the surface of sliding phenomenon， The obtained physical field data were presented in the form of cloud chart and change curve by post⁃processing software for research and analysis. The volume flow rate of the extrusion process under different conditions was calculated， and the tracer particle method was used to explore the movement trajectory of the material in the flow channel. It is found that the wall slip condition is conducive to improving the pressure building ability and shear ability of the counter⁃rotating twin screw at the screw engagement， and the screw slip condition is conducive to the stability of the pressure in the flow channel during the extrusion process， so that the local high pressure phenomenon disappears and the service life of the machine is prolonged. The shear capacity of the counter⁃rotating twin screw decreases at the gap between the screw and the barrel under both sliding conditions. Both slip conditions will decrease the extruding flow rate of the hetero⁃twin screw， resulting in a longer residence time of the material during extrusion.

Key words: twin screw extruder, different meshing, polylactic acid, slip phenomenon, finite element analysis

CLC Number:

TQ320.66⁺3

XU Zhen, HUANG Zhigang, CHENG Yuanyuan. Influence of different slip conditions on the extruding process of PLA in counter⁃rotating twin screw[J]. China Plastics, 2024, 38(12): 115-122.

Figures/Tables 27

螺杆外径/mm	螺杆内径/mm	中心距/mm	导程/mm	头数/个
25	16	21	25	2

Tab.1. Screw element geometric parameters

Fig.1. 3D screw model

Fig.2. Turn inward

Fig.3. Turn outward

Fig.4. Screw conjugate fit

Fig.5. Screw non⁃conjugate fit

机筒内径/mm	中心距/mm	长度/mm
26	21	25

Tab.2. Flow channel area geometric parameters

Fig.6. 3D flow channel model

零剪切黏度

$η 0$ /Pa·S

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