Based on the rheological properties of high impact polystyrene plastic melt in the mold cavity , taking the injection molding process of air-conditioning frame as the object , injection molding process system and HIPS material characteristics of injection molding were analyzed in depth . The influence of the temperature field on the formation of the shrinkage marks during the pressure maintaining and cooling process was analyzed . The greater the difference between the melt solidification layer temperature and mold cav-ity wall temperature is ,the greater the shrinkage defect is . And the shrinkage caused by the thermal residual stress was also analyzed . It is concluded that the greater instant cooling speed and the instantaneous temperature was , the larger strain rate will lead to greater shrinkage defects . And the molding process of air-conditioning frame was verified by injection molding experiment .%基于高抗冲聚苯乙烯(HIPS)塑料熔体在模具型腔中的流变特性,以空调框罩的注塑工艺为研究对象,对注射成型的工艺系统及HIPS材料特性进行了深入分析.针对保压及冷却过程中的温度场变化对缩痕形成进行建模分析.结果表明:熔体凝固层温度与模具型腔壁温度的温差越大,缩痕缺陷越大.同时又对热残余应力导致的缩痕进行了建模分析,得出即时降温速度和瞬时温度梯度越大,较大的应变速率将会导致更大的缩痕缺陷产生.并通过注射试验验证了空调框罩的成型工艺.
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