The isothermal viscoelastic finite element method is used to simulate and analyze the process of cable coating extrusion, in which the Navier slip model is adopted. The Phan–Thien–Tanner differential viscoelastic constitutive equation is used to describe the flow characteristics of the polymer melt. The polymer material used for simulation is polypropylene. The extrudate swell, velocity field, pressure field and shear stress field are calculated by finite element method. The influences of the gas-assisted extrusion and traditional extrusion on wall slip of cable coating extrusion are compared. The results indicate that the extrudate swell ratio is the largest under the condition of the complete slip between core wire and melt during traditional extrusion process. The increase of core wire dragging velocity can lead to the increase of slip velocity, the decrease of pressure and the increase of shear stress of melt. Gas-assisted extrusion can eliminate the negative effects caused by the slip of core wire or the increase of core wire dragging velocity. Therefore, gas-assisted extrusion can reduce the energy consumption, improve the cable coating layer quality and increase the production efficiency during extrusion process.

中文翻译：

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气体辅助挤压对电缆包覆过程中滑移的影响

采用等温粘弹性有限元方法对电缆涂层的挤压过程进行了模拟和分析，采用了Navier滑动模型。Phan–Thien–Tanner微分粘弹性本构方程用于描述聚合物熔体的流动特性。用于模拟的聚合物材料是聚丙烯。采用有限元方法计算出挤出物的胀大，速度场，压力场和剪切应力场。比较了气体辅助挤压和传统挤压对电缆涂层挤压壁滑的影响。结果表明，在传统挤出工艺中，在芯线与熔体完全滑动的条件下，挤出物的溶胀率最大。芯线拖曳速度的增加会导致滑移速度的增加，压力的降低和熔体剪切应力的增加。气体辅助挤压可以消除芯线打滑或芯线拖动速度增加所带来的负面影响。因此，气体辅助挤出可以减少能耗，提高电缆涂层质量，并提高挤出过程中的生产效率。