间隙对电热变模温高光注塑模具加热效率的影响

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。

Effect of Gap on Thermal Response Efficiency in Heating Process of RHCM

The defects such as weld bond,floating fiber,sliver veins etc in traditional injection molding can be eliminated by rapid electric heating cycle injection molding technology. Rapid electric heating cycle injection molding technology requires rapid dynamic control of mold temperature. There is an unavoidable gap between the mounting holes and heaters,and the air in the gap layer greatly prevents heat from being transferred to the mold. Effect of the gap on thermal response efficiency in the heating process of rapid heat cycle molding (RHCM) was studied. By construcing the corresponding thermal response analytical 3D models for RHCM and conducting thermal response analysis on base of ANSYS,these simulation results was verified by experiments. These results show that smaller the gap is ,higher the temperature of the mold surface is and lower the temperature of the electric heating rod is at the same time of heating,so higher the efficiency of heating is. When the gap is 0.05 mm and heating time is 60 s, the temperature of mould surface is 50% higher and the temperature of the electric heating rod is 55% lower at least than which is 0.32 mm. Effect of the gap on thermal response efficiency is not a linear relationship,the gap is smaller,the heating efficiency is more sensitive. These researches provide the basic information for structure design and selection of heat rod.