HIPS微孔发泡注塑成型工艺及数值模拟研究

发布时间：2019-03-02 07:57

【摘要】：微孔发泡注塑成型技术是一项将微孔发泡工艺与注塑成型技术相结合的新技术,能够在保证制品性能的前提下实现减重,因其具备产业化潜力、能够成型复杂形状制品,已获得广泛应用。高冲击强度聚苯乙烯(HIPS)作为一种通用的工程塑料,应用非常广泛。针对HIPS微孔发泡注塑成型技术,研究制品的泡孔形成过程、泡孔形态及性能等,能够有力促进微孔发泡注塑成型技术的应用与发展,具有重要的理论和工程意义。本文采用实验和数值模拟方法,主要针对HIPS微孔发泡注塑成型中工艺参数对试样泡孔形态、力学性能等进行了较为系统的研究,掌握了发泡试样成型过程中泡孔的形成过程,确定了各个成型工艺参数对泡孔形态的影响程度;获得了打气时间及打气延时时间对试样泡孔形态力学性能的影响规律及原因和拉伸温度对发泡试样拉伸性能的影响规律。主要研究工作如下:基于Autodesk Moldflow Synergy 2016,建立了 HIPS/超临界N2微孔发泡注塑成型制品的CAE分析模型,进行了充填+保压+翘曲分析,研究了微孔发泡注塑成型过程中泡孔形态的变化。此外,针对本文研究中模具的型腔分布,分析了料流平衡对发泡过程的限制作用,为开展实验研究提供指导。以泡孔平均半径为研究指标,设计了正交试验,借助信噪比分析和方差分析方法,研究了工艺参数对泡孔平均半径的影响程度,进一步确定了实验研究的重点。打气量直接影响着制品成型时泡孔的形核、长大、合并及分布,对发泡制品的泡孔形态及性能影响十分显著,因此,本文首先研究了打气原理,分析了打气过程中可能会影响制品泡孔形态的打气参数。利用实验室开发的微孔发泡注塑成型设备,研究了打气时间对制品泡孔形态、泡孔形成过程和力学性能的影响,结果表明打气时间对制品的泡孔形态和泡孔形成过程造成显著影响,未发泡皮层厚度和泡孔结构的变化对试样的力学性能产生了影响。研究了打气延时时间对制品泡孔形态和力学性能的影响,结果表明打气延时时间通过改变打气区间,从而影响打气速度,最终影响制品的泡孔形态,进而影响力学性能。利用带有高低温箱控制系统的万能电子拉伸试验机,研究了 HIPS微孔发泡注塑成型试样的热拉伸性能,与未发泡试样的热拉伸性能进行了对比分析。通过对比分析发泡试样和未发泡试样在不同温度下的拉伸性能,分析二者变化规律的异同,为发泡制品的实际使用条件及热拉伸性能指标数据提供参考。
[Abstract]:Microcellular foam injection molding technology is a new technology which combines microcellular foaming technology with injection molding technology. It can reduce weight on the premise of ensuring the performance of products, because of its industrialization potential, it can form complex shaped products. It has been widely used. As a general engineering plastic, high impact strength polystyrene (HIPS) is widely used. In view of HIPS microcellular foam injection molding technology, the study on the forming process, morphology and properties of microcellular foam injection molding products can effectively promote the application and development of microcellular foaming injection molding technology, which has important theoretical and engineering significance. In this paper, the morphology and mechanical properties of HIPS microcellular foam injection molding were studied systematically by means of experiment and numerical simulation, and the forming process of foam in foaming sample was grasped. The influence degree of the forming process parameters on the morphology of the foam was determined. The effects of air pumping time and time delay on the morphology and mechanical properties of foam cells and the effects of tensile temperature on the tensile properties of foam samples were obtained. The main research work is as follows: based on Autodesk Moldflow Synergy 2016, the CAE analysis model of HIPS/ supercritical N _ 2 microcellular foam injection molding products was established, and the filling and pressure-retaining warpage analysis was carried out. The change of cellular morphology during injection molding of microcellular foam was studied. In addition, according to the mold cavity distribution in this study, the limiting effect of material flow balance on foaming process is analyzed, which provides guidance for experimental research. Taking the average radius of cell as the research index, the orthogonal experiment was designed. By means of signal-to-noise ratio analysis and variance analysis, the influence degree of the technological parameters on the average radius of the cell was studied, and the emphasis of the experimental study was further determined. Air volume directly affects the nucleation, growth, combination and distribution of foam cells during molding, and has a significant effect on the cellular morphology and properties of foamed products. Therefore, the principle of air pumping is studied firstly in this paper. The inflating parameters which may affect the bubble shape of the products during the process of pumping are analyzed. By using the microcellular foaming injection molding equipment developed in the laboratory, the effects of air pumping time on the cellular morphology, cellular formation process and mechanical properties of the products were studied. The results show that the blowing time has a significant effect on the cellular morphology and the forming process of the foam, and the changes of the thickness of the unfoamed cortex and the cellular structure have an effect on the mechanical properties of the samples. The effects of pump delay time on bubble morphology and mechanical properties of the product were studied. The results showed that the blow delay time affected the pump speed, finally affected the bubble morphology of the product, and then affected the mechanical properties of the product by changing the pump interval. The thermal tensile properties of HIPS microcellular foam injection molding samples were studied by means of a universal electronic tensile tester with high and low temperature box control system. The thermal tensile properties of the samples were compared with those of the unfoamed samples. By comparing and analyzing the tensile properties of foamed and unfoamed samples at different temperatures, the similarities and differences between them are analyzed in order to provide a reference for the actual conditions of application and the data of thermal tensile properties of foamed products.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ328.4

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