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采用电热方式的高光注塑模具可以有效消除传统注塑成型过程中塑件的熔接痕、浮纤、银纹等缺陷。高光注塑成型技术要求对模具温度的快速动态控制,然而在电加热高光注塑成型中,电加热棒与模具安装孔之间不可避免地存在间隙,间隙层内的空气大大阻碍热量向模具传递。研究了电加热棒与模具安装孔之间的间隙对电热变模温加热效率的影响,构建了电加热高光注塑模具的三维热响应分析模型,利用有限元分析软件ANSYS进行了三维瞬态传热分析,得到了在不同间隙下的模具表面和电加热棒内部的热响应曲线,并通过大量实验证明了理论分析和模拟方法的正确性。结果表明,加热相同时间,间隙量越小,模具表面温度越高,电加热棒内部温度越低,加热效率越高,相较于间隙在0.32 mm,间隙在0.05 mm加热到60 s的模具表面温度至少高出50%,电加热棒内部的温度至少低55%。隙量对模具加热效率的影响并非成线性关系,而是间隙量在越小的区间,加热效率对间隙更加敏感,研究结果为电热变模温高光模具结构设计和电加热棒的选用提供依据。
The use of electric high-gloss injection mold can effectively eliminate the traditional injection molding process plastic welding marks, floating fiber, silver and other defects. High-gloss injection molding technology requires rapid dynamic control of mold temperature. However, in electric-heated high-gloss injection molding, there is an inevitable gap between the electric heating rod and the mold mounting hole. The air in the clearance layer greatly hinders the heat transfer to the mold. The influence of gap between electric heating rod and mold mounting hole on heating efficiency of electric heating mold was studied. The three-dimensional thermal response model of electric heating high-gloss injection mold was established. Three-dimensional transient heat transfer was carried out by using finite element analysis software ANSYS The thermal response curves of the mold surface and the electric heating rod under different clearances are obtained. The correctness of the theoretical analysis and simulation methods is proved through a large number of experiments. The results show that with the same heating time, the smaller the amount of clearance, the higher the mold surface temperature, the lower the internal temperature of the electric heating rod, the higher the heating efficiency. Compared with the die surface with the clearance of 0.32 mm and the clearance of 0.05 mm heated to 60 s The temperature is at least 50% higher and the temperature inside the electric heater is at least 55% lower. The effect of void volume on the heating efficiency of the mold is not a linear relationship, but the smaller the gap is, the heating efficiency is more sensitive to the gap. The results provide the basis for the structural design of electric high temperature mold and electric heating rod selection.