1.商丘职业技术学院机电工程学院，河南商丘 476005； 2.郑州大学机械与动力工程学院，郑州 450001；
Distribution of residual stress and process optimization in gas-assisted injection moldedpolycarbonate products
DAI Zhansheng1, JIANG Jing2, HE Jiafan3
1.College of Mechanical and Electrical Engineering, Shangqiu Polytechnic, Shangqiu 476005,China; 2.School of Mechanical andPower Engineering, Zhengzhou University, Zhengzhou 450001,China; 3.Yutong Bus Co.,Ltd.,Zhengzhou 450061,China
摘要：聚碳酸酯(PC)注塑制品出模后在无外加约束条件下内部应力得不到松弛释放，易导致制品产生开裂，严重影响制品的服役性能。 为探究PC制品内应力分布规律 ，找到有效降低内应力的工艺措施，基于气体辅助注射成型(GAIM)工艺和自行设计制造的带有半圆形加强筋的平板试验模具，结合光弹法和溶剂检测法 ，研究GAIM制品内应力的分布特点，讨论注气压力和气体保压压力两种工艺参数对GAIM 制品内应力的影响规律，提出两种改善制品内应力的工艺方法。研究发现：通过光弹法观测到的应力条纹分布与溶剂浸泡后的裂纹开裂区域一致，即GAIM制品末端及边缘处内应力较大，沿气道两侧应力分布较均匀；较高的注气压力和较低的气体保压压力可以更加有效减小 GAIM制品的内应力；通过对GAIM制品 24 h 即时退火和延长二次注气的卸压时间可以有效降低制品内应力。
Abstract：The residual stress in injection molded polycarbonate(PC) products cannot be relaxed and released without external constraints after demolding, leading to the risk of product cracking, which significantly affects its performance. The aim of this study is to investigate the distribution of residual stress in PC products and identify effective process to reduce it. Based on the gas-assisted injection molding(GAIM) technology, a self-designed flat plate test mold with semicircular ribs was utilized combined with photo‐ elasticity and solvent detection methods. To explore the distribution characteristics of residual stress in GAIM products, the effect of gas injection pressure and gas holding pressure on the residual stress of GAIM products was discussed, and two process methods to improve residual stress in GAIM products were proposed. It was found that stress pattern observed through photoelasticity was consistent with the crack and fracture areas after solvent immersion. Secondly, it was noted that higher gas injection pressure and lower gas holding pressure can effectively reduce residual stress in GAIM products. Finally, immediate annealing within 24 hours and secondary gas injection process were found effective in reducing residual stress in GAIM products.
Keywords：gas-assisted injection molding; polycarbonate; process parameter; internal stress; annealing
DAI Zhansheng，JIANG Jing，HE Jiafan. Distribution of residual stress and process optimization in gas-assisted injection moldedpolycarbon‐ate products[J]. Engineering Plastics Application，2024，52(1)：84-88.