模内微装配成型二次充填熔体应力松弛特性研究

Study on Stress Relaxation Characteristics of Secondary Injection Melt for In-Micro Mold Assembly

模内微装配成型二次充填熔体的冷却收缩自紧特性是保证界面可运动性能的关键影响因素,聚合物材料的应力松弛特性可以使微装配界面上的收缩自紧压力逐渐恢复。以线性黏弹性力学理论为基础,Prony级数形式描述黏弹性积分核函数,对模内组装成型低密度聚乙烯(LDPE)/不锈钢(STEEL)运动副界面收缩自紧应力松弛进行了研究。研究表明,以结构单元所采用的Prony级数形式适用于模拟运动副界面收缩自紧的应力松弛现象;同时经应力松弛后,运动副界面收缩自紧力呈现下降趋势,下降程度高达60%左右。

The cooling,shrinkage and self-tightening characteristics of the secondary filling melt in in-mold micro-assembly were the key factors to ensure the motility of the interface.The stress relaxation characteristics of polymer materials can gradually restore the shrinkage and self-tightening pressure of the micro-assembly interface.Based on the theory of linear viscoelastic mechanics and the Prony series to describe the viscoelastic integral kernel function,the self-tightening stress relaxation at the interface shrinkage of LDPE/stainless STEEL moving pair assembled in the mold was studied.The results show that the Prony series are suitable for simulating the stress relaxation phenomenon of the interface contraction and self-compacting of the moving pair.At the same time,after the stress relaxation,the contractive self-tightening force at the interface of the motion pair presents a downward trend,which is up to 60%.