【作者】 杜彬；

【导师】 谢鹏程；

【作者基本信息】 北京化工大学 ， 机械设计及理论， 2011， 硕士

【摘要】 随着航空航天,生物医学等高新技术的发展,精密注射成型技术的应用领域越来越广泛,这也对精密注射成型技术提出来越来越高的要求。残余应力是注射成型技术中一种常见的成型缺陷,它不但影响着制品的外观质量,而且还严重地影响着制品的光、电、力学性能。注射成型过程中,制品的残余应力主要包括热残余应力和流动残余应力。由于热残余应力比流动残余应力大一个数量级,目前学术界和一些模拟软件通常忽略制品的流动残余应力或是简单地附加一个修正系数。但是对于光学级制品来说,流动残余应力严重地影响着制品的透光性能,尤其是一些精密的光学透镜镜片。本文从光弹性原理出发,结合动态透射光式可视化技术,开发出了一套光学级制品的动态内应力可视化实验系统,并使用该系统对矩形型腔中流动残余应力的形成机理,分布规律进行系统研究。通过对比不同工艺参数和模具结构下制品双折射条纹的区别,并结合偏光显微镜对制品流动残余内应力的计算和moldex3D软件对不同型腔结构在不同模具温度下,高分子熔体流动充填的剪切应力、温度场、压力场进行模拟,总结出注射温度、保压压力、模具结构和温度对流动残余应力的影响规律。对光学级制品的注射成型,提出指导性工艺准则。通过精密注射成型可视化实验系统,直观地研究了三种典型矩形型腔内高温熔体在型腔中的流动行为,研究得到矩形型腔内制品熔接痕和喷射缺陷形成机理。通过分析模具结构设计、成型工艺参数与熔体宏观流动行为及制品宏观缺陷之间的内在联系,提出了解决熔接痕和喷射缺陷的具体措施。更多还原

【Abstract】 With the development of aerospace, biomedical and other high-tech, precision injection molding technology are becoming increasingly widespread, it also made a higher requirements to precision injection molding technology.Residual stress is a common molding defect in injection molding technology. It not only affects the appearance of quality products, but also seriously affects the product’s optical, electrical, mechanical properties. In the injection molding process, residual stress includs thermal residual stress and flow residual stress. Because the thermal residual stress is much larger than the flow residual stress, the flow residual stress is usually ignored in academic research,or used a fixed parameters.But to optical products, the flow residual stress seriously affects light transmission. Especially to some sophisticated lens and glass lens, the flow residual stress became a lethal threat.In this paper,with the help of the photoelastic and light transmission visualization device, we developed a dynamic internal residual stress visualization system.And by using this system,we found the distribution and formation mechanism of the flow residual stress.By comparing the difference between birefringence stripes in different process parameters and mold structure products, and using polarizing microscope to calculate the flow residual stress and using the software of moldex3D to simulate the shear rate, temperature field, pressure field of the melt, we conclude that the injection pressure, packing pressure mold structure on the flow residual stress impact the flow residual stress of the products. The process guidelines is provided for the optical-grade products in injection molding process.In this paper, with precision injection molding systems of visualization experiments,we study high-temperature melt flow behavior in three typical rectangular cavities and get formation mechanism of the weld line and jetting phenomenon.By analyzing connection between mold design parameters and flow behavior,we obtained the means to solve the weld line and jetting phenomenon.更多还原