壁面滑移条件下UHMWPE单螺杆挤出过程有限元模拟

Finite Element Simulation of UHMWPE Single Screw Extrusion Process Under Wall Slippage Condition

在壁面滑移条件下建立了超高分子量聚乙烯(UHMWPE)单螺杆挤出过程有限元模型,模拟了不同滑移系数对挤出成型过程的影响。由Navier线性滑移定律建立了螺杆壁面熔体所受剪切应力与熔体滑移速度之间的关系,基于Polyflow软件,采用不同滑移系数对单螺杆计量段内UHMWPE熔体的三维等温流动开展了有限元模拟,获得了熔体的速度、压力的分布规律。结果表明:滑移系数增大,沿着螺槽方向的速度和垂直于螺槽方向的速度明显增大,螺杆的均化质量和挤出产量明显提高;但熔体在螺槽间的压力降增大,易导致挤出过程不稳定。

Under the condition of wall slippage, finite element model of UHMWPE single screw extrusion process was established, the influence of different slip coefficient on the extrusion forming process was simulated. The relationship between the screw wall shear stress and the slip velocity of the flowing melt follows the Navier linear law; with different slip coefficient, three-dimensional isothermal flow of the UHMWPE melt was simulated using finite element method by the Polyflow software, the melt velocity and pressure distribution was obtained. The results show that： with the increase of slip coefficient, the speed along the direction of spiral groove and in vertical direction of the spiral groove increases obviously. The homogenization of quality and the yield of the screw increases significantly, but the pressure drop of the melt in the spiral groove increases, that easily leads to instability in the process of extrusion.