Flow field analysis and design optimization of flow channel of degradable plastic sheet head

doi:10.19491/j.issn.1001-9278.2023.09.013

Abstract

Abstract:

This paper focused on the irregular and wavy⁃like wrinkle problems in the surface of the sheets extruded by using a degradable plastic extrusion head. The extrusion process of a degradable plastic sheet was simulated by means of Polyflow， and the distribution of speed， pressure and shear rate in the extrusion process were calculated and analyzed. The flow channel structure of the extrusion head was optimized according to the numerical simulation results and compared with the original organic head flow channel. The results indicated that the optimized head flow channel not only improved the melt flow velocity but also enhanced the melt flow performance of the inlet. The pressure drop of the forming section in the runner was improved， resulting in an improvement in the mold filling speed and melt flow rate. The shear rate of the extrusion head was improved. This was advantageous to the uniform mixing of materials in a runner. As a result， the problems in irregularity and surface wrinkle of the sheets were solved.

Key words: degradable plastic sheet, flow channel of machine head, Polyflow, numerical simulation, structural optimization

CLC Number:

TQ320.66⁺3

ZHOU Lei, ZHANG Lihua, CHEN Gingming, MAO Xu, CHEN Shuguang, QIU Jiancheng. Flow field analysis and design optimization of flow channel of degradable plastic sheet head[J]. China Plastics, 2023, 37(9): 90-95.

Figures/Tables 13

Fig.1. Solid diagram of the sheet head

Fig.2. Runner model of the sheet head

Fig.3. Maximum outlet velocity of melt at different mesh quantities

Fig.4. Meshing

Fig.5. Schematic diagram of nozzle flow channel optimization

Fig.6. Comparison of runner model optimization

Fig.7. Numerical analysis of melt velocity field in the nozzle runner

Fig.8. Comparison of export velocity distribution of different sections before and after optimization

Fig.9. Numerical analysis of melt pressure field in the nose runner

Fig.10. Comparison chart of outlet pressure distribution of different sections before and after optimization

Fig.11. Numerical analysis of melt shear rate field of machine head runner

Fig.12. Comparison of outlet shear rate distribution of different sections before and after optimization

Fig.13. Comparison of extruded sheet effect before and after sheet head flow channel optimization

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