Discrete element analysis of solid conveying section of double⁃cone screw extruder

doi:10.19491/j.issn.1001-9278.2022.04.013

Abstract

Abstract:

The solid conveying section of a common cone and two double cone screw extruders was simulated using the EDEM software. The motion state and distribution law of PE?HD particles in a conical twin?screw extruder were analyzed. The parameters of mass flow rate， filling rate， average speed， average pressure， average shear stress and torque of three conical screw extruders were investigated comparatively， and the solid conveying mechanism of ordinary and double conical screw extruders and the corresponding influence factors were discussed. The results indicated that compared to the ordinary conical twin?screw extruder， the twin?conical screw extruder exhibited relatively smaller axial velocity changes， stronger pressure building capacity， and higher volume filling. This is suitable for the processing of shearing?sensitive materials.

Key words: conical twin screw, EDEM software, solid conveying, conveying efficiency

CLC Number:

TQ320.66⁺3

WANG Haolin, ZHU Xiangzhe. Discrete element analysis of solid conveying section of double⁃cone screw extruder[J]. China Plastics, 2022, 36(4): 83-88.

Figures/Tables 13

Fig.1. Particle contact model and damping model

挤出机型号	小端直径/mm	大端直径/mm	小端槽深/mm	大端槽深/mm	螺棱宽度/mm	螺杆导程/mm	计算域长度/mm	槽深与直径比
SZ30⁃50	30	50	6	6	10	30	150	—
SZ30⁃60	30	60	6	12	10	30	150	0.20
SZ25⁃50	25	50	6	12	10	30	150	0.24

Tab.1. Screw structure parameters

Fig.2. Geometric model of screw and barrel

Fig.3. The movement state of the particles in the extruder at different time

Fig.4. Schematic diagram of tracer particles

Fig.5. Cloud diagram of particle velocity in the range of 30~150 mm in axial length of three extruders

Fig.6. Curves of average speed versus axial distance

轴向距离/m	平均速度/m•s^-1
轴向距离/m	SZ30⁃50	SZ30⁃60	SZ25⁃50
0.3	0.048	0.055	0.026
0.5	0.046	0.041	0.022
0.7	0.064	0.069	0.035
0.9	0.036	0.044	0.018
1.1	0.047	0.054	0.026
1.3	0.045	0.067	0.018
1.5	0.040	0.049	0.014

Tab.2. The average particle velocity varies with the axial distance

Fig.7. Curves of average pressure versus axial distance

Fig.8. Average shear stress change curves with axial distance

Fig.9. Mass flow rate change curves

Fig.10. Volume filling rate change curves with time

Fig.11. Torque curves with time

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