Wear characteristics of twin⁃screw extruder based on discrete element method

doi:10.19491/j.issn.1001-9278.2023.11.015

Abstract

Abstract:

Twin⁃screw extruders often have problems such as screw wear in the production process， which seriously affects the service life of the screw and the quality of polymer processing. The screw wear of twin⁃screw extruder was simulated numerically by using a discrete element method and Archard wear model， and the effect of screw speed and filling rate on the wear characteristics of twin⁃screw extruder was analyzed. The results indicated that the screw wear mainly occurred in the top area of the screw edge and the inlet of the feed， and serious extrusion wear occurred at the entrance of the material entering the barrel. The wear degree of screw increased continuously with an increase in the screw speed and filling rate. The screw in the rear conveyor section of the feed trough mainly produces transverse cutting wear， and the tangential accumulated energy is the key factor which leads to wear.

Key words: twin screw extruder, solid transfer section, Archard wear model, screw wear

CLC Number:

TQ320.5

GAO Kun, YAN Wei, LIU Zhigang, ZHU Xiangzhe. Wear characteristics of twin⁃screw extruder based on discrete element method[J]. China Plastics, 2023, 37(11): 135-140.

Figures/Tables 15

Fig.1. Geometric model of twin screw extruder with simultaneous meshing

挤出机几何参数	数值
螺杆顶径	50
螺杆根径	26
螺杆中心距	38
机筒内径	52
螺距	45
螺杆长度	315

Tab.1. Basic geometric parameters of the twin screw

Fig.2. Finite element mesh model of the twin screw extruder with simultaneous meshing

材料	密度/kg•m^-3	弹性模量/GPa	泊松比
PE⁃LD（颗粒）	923	0.18	0.44
碳钢（挤出机）	7 850	203	0.30

Tab.2. Material properties of the extruders and particles

相互作用	恢复系数	静摩擦系数	滚动摩擦系数
颗粒⁃颗粒	0.50	0.60	0.01
颗粒⁃机筒	0.50	0.35	0.01
颗粒⁃螺杆	0.50	0.25	0.01

Tab.3. Contact properties between the materials

Fig.3. Surface wear distribution cloud map of the twin screw engaged in the same direction

Fig.4. Cumulative energy distribution on the surface of the twin screw engaged in the same direction （top view）

Fig.5. Change of average cumulative contact force with time

Fig.6. Change of wear rate with position

Fig.7. Cloud map of particle filling distribution at different filling rates （top view）

Fig.8. Screw wear distribution cloud map under different filling rates （top view）

Fig.9. Change of wear rate with position under different filling rates

Fig.10. Change of filling rate with time under different velocity conditions

Fig.11. Screw wear distribution cloud map under different speed

Fig.12. Change of wear depth with screw speed

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