【作者】 乔飞；

【导师】 宋满仓；

【作者基本信息】 大连理工大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 随着塑料性能的改善和注塑成型技术的发展，塑料制品的应用范围越来越广，同时人们对注塑制品的精度和质量要求越来越高，然而注塑制品的收缩不仅影响了制品的尺寸精度与表观质量，而且严重时还会引起制品结构变形与内在质量缺陷。精密注塑模具设计时的收缩率选取和注塑工艺参数设定已成为精密注塑件生产中的两大难题，所以很有必要对注塑制品收缩规律进行研究。 本课题在全面分析注塑成型收缩研究概况的基础上，用实验对注塑制品收缩规律进行了全方位的研究。首先，利用正交试验研究了注塑工艺参数对注塑制品的收缩率以及收缩各向异性(纵向收缩率和横向收缩率的差异)的影响规律，结果表明，在PP常用的工艺参数范围内，保压压力、保压时间和料温对注塑成型收缩影响较大，而保压压力和注射速度对注塑成型收缩各向异性影响较大。接着在正交实验的基础上，对几种典型形状塑件(方形、凸形、凹形、扇形)的收缩趋势进行了研究，证实了注塑制品是沿着几何中心向内收缩的。最后采用单因素试验法研究了注塑制品厚度对其收缩率的影响规律，发现注塑制品的厚度是影响塑件收缩率的一个重要因素，塑件的成型收缩率随塑件厚度增大而增大，但是这种增大的趋势是非线性的，而塑件收缩各向异性的趋势随着塑件厚度的增大而减小。 最后，本课题还利用注塑成型充模流动的静态可视化技术，观察了注塑成型中塑料熔体的稳态扩展流动形式，通过分析稳态扩展流的三个阶段，清楚了塑料熔体的充模流动过程，对注塑成型有了更深刻的认识。更多还原

【Abstract】 With improvement of property of plastics and development of injection molding technology, injection molding products are used more and more widely, and with higher requirement of dimension accuracy and surface quality. But shrinkage of injection molding products can influence the dimension accuracy and surface quality, even cause structural distortion or in-side defects. Selection of shrinkage rate and process parameter becomes a difficulty in precision plastic parts production. So it is necessary to study the shrinkage laws of injection molding products.On the basis of roundly analyzing study state of shrinkage of injection molding products, shrinkage laws of injection molding products is fully studied via experiment in this paper, At first, the influence of process parameter on shrinkage rate and shrinkage anisotropy (difference between transverse shrinkage rate and longitudinal shrinkage rate) of injection molding products is studied through orthogonal experiment. It’s found that holding pressure, holding time and melt temperature are significant effect factors on the shrinkage rate of injection molding products, while holding pressure and injection rat influence shrinkage anisotropy greatly. On the basis of the former orthogonal experiment, shrinkage trend of some injection molding parts with typical shape (square, convex, concave, sector-shaped) are studied experimentally. Result indicated that plastic parts shrink along its geometry centre. Then a single factor experiment is used to research the regularity of influence of thickness on shrinkage rate. It is indicated that thickness is an important factor of shrinkage rate, the shrinkage rate increase with thickness non-linearly, while shrinkage anisotropy reduce with thickness.At last, a static visualization method for filling of injection molding is used to observe the steady expanding flow of the melt plastic in mold cavity. According to the analysis of the three stages of expanding flow, filling in injection molding is understood more impressively更多还原