基于灰色理论的顺序注射成型工艺参数优化

Optimization of Process Parameters in Sequential Injection Molding Based on Grey Theory

汽车保险杠是大型薄壁塑件,采用传统注射成型很难消除其表面的熔接痕,热流道顺序注塑是解决熔接痕,提高表面质量的一种很好的成型方法。以汽车保险杠为例,采用针阀式浇口,5点进浇,可以使熔接痕控制在产品边缘,但是其翘曲度偏大。根据分析,翘曲度的大小与针阀开启时机密切相关,以保压过程中的压力和针阀开启时刻为主要因素进行正交实验。运用灰色理论,计算出各试验的灰色关联度,并通过极差分析,获取最佳工艺参数值组合。将该最优参数组合在Moldflow软件中进行验证,该产品3个方向的最大翘曲度分别为0.973%,1.12%,1.33%,都小于1.5%,满足生产要求,这种热流道顺序注射成型方法成功的解决了塑件熔接痕的问题,同时对针阀开启时机的优化成功的控制了塑件的翘曲度的大小,这种成型优化方法可以在实际的生产中进行推广应用。

A automobile bumper is a large scale thin - wall plastic part. It is difficult to for the weld lines of product to be removed by conventional injection method. Hot runner sequential injection molding is a effective method to solve weld line of plastic parts and im- prove quality of products surface. Five valve gates in sequential injection have been used to control weld lines at the border, but the warp degree of the product is too large. According to analysis, the degree of warp is closely related to time of valves opening. So the packing pressure and time of valves opening are considered as the main factors of warp, orthogonal experiments have been carried out. Through grey theory, the grey relational degree have been calculated, the optimal process parameters group have been obtained by vari- ance analysis. The result has been verified successfully in Moldfiow software, the warp degree of product in three directions are respec- tively 0. 973 % , 1. 12 % , 1.33 % which are less than 1.5% and satisfy the requirement. The hot runner injection molding has suc- cessfully solved the weld line and controlled the degree of warp. The optimization method can be spread in actual production.