微注塑充模过程中壁面滑移对熔体流动影响的研究

Study on Effect of Wall Slip on Plastic Melt Flow in Micro-injection Molding Filling

针对微型塑料件注塑充模过程中,壁面滑移对流动的影响不可忽略的情况,运用流体分析软件Fluent,以微阶梯圆形截面通道为模型,在考虑和不考虑壁面滑移的情况下,对微注塑充模流动过程中壁面滑移的影响进行了数值模拟。分析了细通道近壁面处熔体的剪切速率和黏度,发现考虑壁面滑移时近壁面处的剪切速率略大,黏度略低。研究了熔体在粗通道和细通道中沿径向的流动速度和温度分布,以及沿微通道流动方向上的压力分布。结果表明,考虑壁面滑移时熔体流动速度较大,与壁面接触的熔体流动速度不再为零,且微通道截面尺寸越小,这种现象越明显;考虑壁面滑移时近壁面处熔体温度略高,并且粗通道中的这种现象更明显一些;壁面滑移对微通道中的压力分布几乎没有影响。总体而言,壁面滑移有利于微注塑充模。

According to the conditions that wall slip can not be neglected during plastic micro-mjecnon molding hlhng, using Fluent software and taking micro step-shaped round channel as model, effects of wall slip on the micro-injection molding filling was simulated numerically comparing with and without regard to wall slip. The shear rate and melt viscosity near wall were analyzed, it was found that the shear rate was slightly higher and the melt viscosity was slightly lower when considering wall slip. The influences of wall-slip on the distribution of flowing velocity and temperature along radial direction of melt in thick and thin channel, and the pressure distribution along flowing direction of the micro channel were studied. The results show that when considring wall slip, the flowing velocity is faster and the velocity of melt on the wall isn＇t zero, moreover, the more smaller the cross section size of the channel is, the more obvious this phenomenon is. The temperature of melt near wall is slightly higher when considring wall slip and this phenomenon in thick channel is more obvious. Wall slip almost has no effect on the pressure distribution. Overall, the wall slip is conducive to the micro-injection molding filling.