钢塑复合异型材共挤流道内熔体流动特性的数值模拟

结合钢塑复合共挤工艺特点,建立了复合共挤出流动的数学模型。采用有限元分析软件Ansys对钢塑复合中空异型材共挤流道内熔体的三维等温非牛顿流动进行了数值模拟;讨论了内部芯材以不同速率移动时,流道内熔体压力、速度和粘度的分布特点及变化规律,并与普通异型材挤出进行了对比。结果表明:随着芯材移动速率的提高,流道内压降减小;在熔体与芯材接触结合区域,压力和速度梯度明显增加,粘度减小,易出现不稳定流动;流道内熔体有较高的轴向速率,径向速率对称分布,其流动特征为典型的收敛流动;由于芯材在牵动,熔体最大流速出现在口模成型段,即挤出熔体与芯材的会合处。

Numerical Simulation of the Melt Flow Characteristics in Coextrusion Runner of the Steel/Plastic Composite Profile

It established the mathematical model of the melt flow in coextrusion by combining the characteristics of the technology of steel/plastic coextrusion.It simulated the three-dimensional isothermal non-Newtonian flow in the runner of the coextrusion die by using of the FEA Ansys software.It discussed the variation and distribution of flow pressure,velocity and viscosity with different insert moving rate and compared with those of conventional profile extrusion process.The results showed that the pressure drop in runner decreased with the increase of the insert moving rate,and the pressure and velocity gradient obviously increased and viscosity decreased in the merging area of the melts and insert,as well as it was easy to invoke the unstable flow.Axial velocity of the melts in the runner was higher and the radial velocity was symmetrically distributed,which showed a typical convergent flow feature;Due to the core being hauled-off,the max.Velocity of melt occurs where the emerging melt and the core meet.