注塑机止逆螺杆头三维等温流动的数值模拟

Simulations of 3-D Isothermal Flow in the Non-return Screw Head of Injection Moulding Machines

使用聚合物流动分析软件Polyflow,模拟了注塑机止逆螺杆头中的三维等温流场。选用聚苯乙烯(PS)作为模拟流体,分析了塑化和注射两个过程中注塑机止逆螺杆头流道内熔体速度和剪切应力的分布情况,并将无止逆环螺杆头与止逆螺杆头的流场进行了比较。数值模拟结果表明:塑化时熔体速度和剪切应力的最大值均出现在沟槽处,注射时二者均出现在流道出口处;止逆螺杆头沟槽处熔体的回泄量和回泄速度较无止逆环螺杆头小得多,且沟槽处回泄的熔体到达止逆环时已被完全消除。这说明止逆环的存在可以有效地防止熔体回泄。

The 3-D isothermal flow of PS melt passing the non-return screw head in an injector was simulated using a polymer flow analysis package Polyflow. The distributions of the velocity and shear stress near the non return screw head were analyzed for both plasticizing and injecting processes and compared with the case without the non-return ring. It was found that at the plasticizing phase, both the velocity and shear stress maxima occurred at the groove; while at injecting phase, at the exit of the fluid field. The flux and velocity of the backward melt for those with a non-return ring were much smaller than those of without, indicating the backward flowing was efficiently inhibited.