Study on mixing uniformity regulation and control of continuous twin⁃screw mixer

doi:10.19491/j.issn.1001-9278.2022.04.021

Abstract

Abstract:

Aiming at the industry common technical bottleneck in the control of the mixing uniformity and process reproducibility of polymer composites， the synergetic evolution law of the standard relative deviation （RSD） of powder mixing uniformity and process reproducibility with the inlet powder formula ratio， powder cohesive characteristics， and screw speed was simulated， The results indicated that the RSD was negatively correlated with the component content and screw speed， and it had a positive correlation with powder cohesive energy density. The mixing uniformity and process reproducibility of cohesive powders with an ultrafine particle size and an ultralow component content could be enhanced by increasing the screw speed. When the component content was less than 5 % and the energy density was less than 30 000 J/m³， the regulation of mixing uniformity and process reproducibility could be realized by increasing the screw speed up to 1 600 r/min. This can meet the requirement of technical index with a RSD less than 5 %. A regression model for the collaborative coupling correlation control between RSD and screw speed was constructed on the basis of this condition. The real?time online model predictive control of mixing uniformity and process reproducibility in the cohesive powder mixing process at an ultrafine particle size and an ultralow content could be realized by using a speed sensor， a variable frequency drive motor together with the collaborative coupling correlation control regression model. These results provided a technical support for solving the common technical bottleneck in the processing industry of polymer composites.

Key words: continuous mixing, twin screw, uniformity, regulation mechanism, simulation

CLC Number:

TQ320.66⁺3

JIANG Jingwei, LIU Zhenfeng, ZHOU Guofa. Study on mixing uniformity regulation and control of continuous twin⁃screw mixer[J]. China Plastics, 2022, 36(4): 142-148.

Figures/Tables 15

Fig.1. 3D model of continuous twin screw mixer

螺杆长度/

Tab.1. Model dimensions

材料	直径/mm	密度/kg•m^-³	泊松比	剪切模量/GPa	恢复系数	静摩擦因数	动摩擦因数
A粉体	1.0	450	0.25	2.0×10⁶	0.5	0.5	0.01
B粉体	0.2	3 140	0.25	2.0×10⁶	0.5	0.5	0.01

Tab.2. Physical parameters of powder

Fig.2. Relationship between component distribution， uniformity and formula component content

Fig.3. RSD versus time curves based on component content

Fig.4. RSD versus formula B component content curve

Fig5. Relationship between component distribution， uniformity and screw speed

Fig.6. RSD versus time curves based on the influence of screen speed

Fig.7. RSD versus screen speed curve

Fig.8. B component content versus time curve

材料	直径/mm	密度/kg • m^-³	泊松比	剪切模量/GPa	恢复系数	静摩擦因数	动摩擦因数
C粉体	1	800	0.25	2.0×10⁶	0.5	0.5	0.01
D粉体	1	500	0.25	2.0×10⁶	0.5	0.5	0.01

Tab.3. Physical parameters of cohesive powder

Fig.9. Relationship between component distribution， uniformity and energy density

Fig.10. RSD versus time curve based on the influence of energy density

Fig.11. Correlation curves between uniformity RSD and energy density

Fig.12. Correlation curve between cohesive powder component content and time

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