同向双螺杆挤出机过渡段流体的三维数值模拟

THREE-DIMENSIONAL MUMERICAL SIMULATION OF LIQUID IN TRANSITION SEGMENT OF THE CO- ROTATING TWIN- SCREW EXTRUDER

针对某工厂双螺杆挤出机出料速度不均,产品断面有裂纹等问题,应用POLYFLOW软件数值模拟了同向旋转双螺杆挤出机过渡段流道内流体的三维等温流动,给出了物料的粘度和剪切应力随进出口压力、螺杆转速变化的分布规律,重点讨论了工艺参数对过渡段的性能的影响。模拟结果表明:随着进出口压差的增大和螺杆转速的增加,剪切应力均增大,出口物料所受剪切应力梯度变小,过渡段分散混合能力增加,有利于物料在过渡段内的均化。随着螺杆转速的增加,物料在过渡段内停留时间过短会影响物料塑化质量。

To solve the problems of inhomogeneous extrusion velocity and cracking in sections of product in a certain factory, the three- dimensional isothermal flow in transition segment of the co - rotating twin - screw extruder was simulated by using the finite element package POLYFLOW. The distributions of the viscosity and shear stress of material were discussed with the pressures in exit and entrance and rotational speed of screwchanged Effects of the technological parameters on the performance of liquid in transition segment were emphasized. The simulated results show that with the increase of pressure difference in exit and entrance and rotational speed of screw changed, the shear stress increases and the gradient of shear stress of materials in exit decreases, so the ability of dispersive mixture is enhanced and uniformization of materials in transition segment is promoted. With the increasing of the rotational speed of screw, residence time of the polymer melts in transition segment is shortened, which affects the plasticization quality of the polymer melts.