基于Polyfow的吹膜模头熔体流动二维数值模拟

Two-dimensional Numerical Simulation of Melt Flow for Blown Film Die Head Based on Polyfow

对共挤复合吹膜工艺所采用的螺旋芯棒式模头内部熔体流动进行二维数值模拟,简化分析模型并得到挤出过程中熔体流动的流速及压力变化的相对趋势。模拟结果表明:熔体进入模头螺旋部分后具有一定的环向速度,随着螺旋槽深度变浅,流动的方向逐渐由螺旋环向变为挤出方向的轴向,且流速变得均匀;熔体在螺旋槽旋转处静压力较大,接近挤出方向后压力逐渐变小,口模出口处熔体流动速度仍大于流入模头的入口速度。

The melt flow in spiral type die head adopted by co-extrusion lamination plastics film was studied by two-dimensional numerical simulation, which can simplify analysis model and obtain the relative trend of velocity and pressure of melt flow in the extrusion process. The results show that： melt has some spiral direction velocity after flowing into spiral part of die head; the melt flow direction changes gradually from spiral direction to axial direction with the spiral groove depth is getting shallower, and the velocity of flow becomes uniform. The static pressure of melt is high near the spiral groove, and it decreases gradually near the extrusion direction, but the melt flow rate near die exit is greater than the entrance velocity to flow into the die.