注塑成型喷射现象数值模拟及机理分析  

Numerical simulation and mechanism analysis for jetting phenomenon during injection molding

作　　者：花少震 曹伟[1] 张世勋[1] 鲁贵祥 刘春太[1] 申长雨[1] 

机构地区：[1]郑州大学橡塑模具国家工程研究中心,郑州450002

出　　处：《应用力学学报》2016年第4期707-713,744,共7页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(11272291;11432003);973项目(2012CB025900)

摘　　要：喷射是熔体充填过程中一种特殊流动形态,也是注塑成型的不良现象,为了预测射流长度、形态演化,揭示喷射的产生机理,建立了粘性、非等温的熔体三维流动模型,构造了熔体流动前沿演化的输运方程。用有限体积法离散控制方程,提出了压强与速度及速度与温度的两重解耦合方案,开发了模拟程序,分析了模拟成型过程中粘性力、惯性力、速度、温度、压力等物理量的大小及变化规律。基于模拟结果分析了粘性力、惯性力的大小对喷射的影响,发现:当惯性力大于粘性力时产生喷射现象,随着粘性力增大,射流变为蛇形流;射流长度依赖于注射速度,速度越大,射流越长,熔体温度对射流长度基本没有影响。此外,实验结果表明,注塑成型喷射现象数值模拟及机理分析方法可以较好地预测射流长度、蛇形流的形态以及蛇形流中、后端摆动幅度。Jetting is a special flow form of melt filling and a bad phenomenon of injection molding. In order to predict jetting length, shape evolution and explore the mechanism, a three dimensional melt flow model is founded in terms of viscous and non-isothermal fluid, and the mass transport equation of melt front is also constructed. The finite volume method is employed to discretize the governing equations. In order to solve the equations separately, an iterative method is proposed to decouple the relationship between pressure and velocity, and the dependence between velocity and temperature. Based on the proposed theoretical model and numerical method, a program is developed to simulate viscous force, inertial force, pressure, velocity and temperature during injection molding. Influence by the competition between viscous force and inertial force on jetting front is analyzed based on the numerical results. This study indicates jetting originates when inertial force is greater than viscous force, jetting switches to reptile flow as viscous force competes over inertial force, jetting length increases with injection rate, and the melt temperature has little influence on the jetting length. The experimental result implies that the proposed method can correctly predict the jetting length, the reptile shape, and the vibrating amplitude of middle and rear parts of the reptile flow.

关 键 词：喷射 有限体积 Cross-WLF VOF方法 注塑成型 

分 类 号：O373[理学—流体力学]