【作者】 杜辉；

【导师】 刘春太；

【作者基本信息】 郑州大学 ， 材料加工工程， 2011， 硕士

【摘要】 随着微机电系统和微／纳米技术的发展,微成型技术得到了快速发展,其中微注塑成型技术成为各国研究的热点之一。由于微注塑成型制品尺寸微小或精度等级高,传统的注塑成型理论及成型工艺不适用于微注塑成型。目前对于微注塑成型理论的还不完善,微注塑成型工艺还需要进一步的探索。微注塑成型制品可以分为两大类,一类是整个制件本身的尺寸都是微观尺度；一类是宏观尺度的制件上局部带有微观特征。本文对带有微特征的注塑件进行了充填模拟,重点探讨了微特征入口区域的复杂流动行为。论文主要的工作包括：1.熔体在微流道入口区域的流动类似于变压力驱动的切变方腔流。通过对宏观制件和微观制件的耦合模拟,我们发现当主流道的速度与流体粘度的比值U/η≥100时,微流道入口区域并不能完全充满,微流道入口区域会有气旋出现,导致制品在微特征区域出现空洞。2.对带有微特征的注塑件进行结构多尺度模拟,不考虑主流道熔体剪切力对微流道熔体的影响,主要关注微流道的充填长度。通过对注塑件宏观区域的模拟,得到微流道入口处压力的变化历史和熔体温度,并将变压力函数和熔体温度作为边界条件,利用ANSYS CFX对微特征结构的充填过程进行了进一步的数值模拟。详细分析了模具温度、注射速度、微流道入口压力、微流道宽度等工艺和几何因素对微流道充填长度的影响。3.考虑主流道熔体剪切力对微特征区域的影响,对制件进行宏微观解耦模拟,并对微流道进行准静态方腔流分析。从模拟结果得到,在微流道入口处由于受到X方向和Y方向两个速度的影响下,熔体出现分离的流动,向下充填的同时不断的回旋,出现涡流中心。在主流道速度较大时,涡流中心混杂着空气,主流道速度较小时,涡流中心完全为聚合物熔体。更多还原

【Abstract】 As the development of MEMS and Micro/Nano technology, the micro forming technology had a rapid development, and the micro injection molding technology has becoming the hot spot of all the countries. Due to products with the micro injection molding have tiny size or highly accuracy level, the traditional injection molding theory and technology shall not be used for micro injection molding. At present the micro injection molding theory is not perfect, and the micro injection molding process methods still need further exploration.Products of Micro injection molding can be classified into two categories, one kind is the drawing of the size is microscopic scale; The other kind is the macro scale parts with microscopic features.In this paper we simulated the filling process of injection molding with micro-features, mainly discussed the complex flow behavior in the micro characteristics of entrance areas. The main work includes:1. The flow in entrance areas of micro channel is similar to variable pressure drive square lumen flow. Through the coupling simulation of the microscopic and microscopic parts, we found that the entrance areas cannot be completely filled whenU/η≥100, there will have a vortex.2. Based on multi-scale method we simulate the filling length of micro-channel, not considering the influence of melt shear force in macro-channel. Through the filling simulation of the macro area, we get the history of pressure at the entrance micro channel and melt temperature, then taking the variable pressure function and melt temperature as boundary conditions, we simulate the filling process of the micro-channel used ANSYS CFX. We detailed analyze the influence of mould temperature, injection velocity, pressure at inlet region of micro-channel and width of micro-channel to the filling length.3. We simulate the filling process of micro-channel based on macro and micro decoupling method, considering the influence of melt shear force in macro-channel, and analyze quasi-static square cavity flow. The results show that under the influence of X and Y melt flow directions at the micro-channel inlet region, melt rotate when filling the micro-channel, and then the vortex center appears. If the speed of melt in main channel is bigger, the vortex mingled with air; if the speed is less, vortex is completely full of polymeric melt.更多还原