塑化过程螺杆计量段三维流场的数值模拟

采用CROSS模型表示聚氯乙烯的黏度特征,使用POLYFLOW软件数值模拟了塑料注塑成型机头部无螺纹和有螺纹的螺杆计量段流道内熔体在塑化过程的三维等温流场,求解和分析了两种螺杆流道的yz和xy截面上不同时刻的速度场、压强场、黏度场和剪切应力场。计算结果表明,两种螺杆元件产生的流场差别较大。有螺纹的注塑螺杆头部附近聚氯乙烯熔体逆流速度和压强增大,引起剪切应力的增大,加强了螺杆头部聚氯乙烯熔体的剪切稀化作用,使得熔体黏度降低。

Simulations of Three- Dimensional Flow Fields in Metering Section of Screw During Plasticization Process

The viscosity characteristic of polychloroethylene was expessed by CROSS model.Three-dimensional isothermal flow fields of a cross fluid in the metering section of injection molder with different screw heads during plasticization process were simulated by using POLYFLOW software.The velocity fields,pressure fields,viscosity fields and shear stress fields in the yz ang xy section at different time were analyzed in details respectively.The results show that there are significant differences in the flow fields generated between the screw elements. The z-velocity field is greatly affected by the screw thread in the screw head,so the velocity of the adverse flow and the pressure of the polychloroethylene melt increase,the shear stress is increased,shear dilution action of polychloroethylene melt in the screw head is strengthened and the viscosity decreases.