气体辅助注射成型时间参数的CCD响应面法多目标优化

Multi-objective optimize gas-assisted time parameters with CCD response surface method

相比于传统塑料注射成型,延迟时长和注气时长是气体辅助注射成型(简称气辅成型)特有的工艺参数,增加了气辅成型的复杂性。为了精确设计延迟时长和注气时长的取值,获得理想的气体穿透效果和气指幅度,以具有典型气辅结构的塑件为研究对象,首先采用气辅成型全三维CAE研究了延迟时长和注气时长对气辅成型质量的影响。结果表明,适当增加延迟时长,可以减小或消除气指缺陷,提高气体穿透深度行程,但过长的延迟时长会导致“短射”,过短的延迟时长则会导致严重的气指缺陷;增加注气时长可以提高气体穿透效果,减少表面缺陷,降低内应力和翘曲变形,但注气时长过长时,气指内部的高压氮气会导致其撕裂而形成严重的气指缺陷,更甚者会使气辅塑件膨胀而报废。采用CCD响应面法进行多目标优化,精确设计了延迟时长和注气时长的取值,延迟时长为4 s、注气时长为10.37 s。通过CAE分析和成型试验验证,精确取值下成型的气辅塑件的气体穿透效果和气辅成型质量良好,提高了气辅成型质量和效率,可用于气辅成型实际生产。

Compared to traditional plastic injection molding,delay time and gas injection time are unique parameters for gasassisted molding,which increases the complexity of gas-assisted molding.In order to accurately design the values of delay time and injection time,and achieve ideal gas penetration effect and gas finger amplitude,the plastic part with typical gas-assisted structures were taken as research object.Firstly,the effects of delay time and gas injection time on the quality of gas-assisted molding were studied by gas-assisted molding full three-dimensional CAE.The results show that properly increasing the delay time can reduce or eliminate the gas finger defects and improve the penetration length,but too long delay time will lead to"short shot",and too short delay time will lead to serious gas finger defects.Increasing the gas injection time can improve the gas penetration effect,reduce surface defects,and reduce internal stress and warping deformation.However,if the gas injection time is too long,the high-pressure nitrogen part inside the gas finger will tear it to form serious gas finger defects,and even cause the plastic part to expand and become scrapped.Then,the CCD response surface method was used for multi-objective optimization,and the optimal values of delay time and gas injection time were obtained as 4 s and 10.37 s,respectively.The optimized values are verified through CAE and experiments,and the gas penetration effect and gas assisted molding quality under the optimized values are good,which improves the quality and efficiency of gas-assisted molding and can be used for actual production of gas-assisted molding.