汽车B柱外饰板双色注塑翘曲变形分析及工艺优化

Warpage Deformation Analysis and Process Optimization of Automotive B-pillar Exterior Panel with Two-color Injection

以某汽车B柱外饰板塑件[由聚甲基丙烯酸甲酯(PMMA)/丙烯腈-丁二烯-苯乙烯塑料(ABS)两种材料组成]为研究对象,以厚度比、熔体温度、保压压力、保压时间为影响因素,结合拟水平法进行Taguchi正交试验设计,基于Moldflow软件进行模拟仿真,并对试验数据进行极差、方差分析处理,最后得出最佳的双色注塑工艺组合方案。结果表明,厚度比是影响塑件翘曲变形量的最为重要的因素,其次是保压时间、保压压力,最后是熔体温度。在总厚度不变的情况下,改变PMMA/ABS的厚度比值,塑件所产生的翘曲变形量将发生改变,第一次注射的厚度越薄,所产生的翘曲变形量越大,当厚度比越趋近于1时,所产生的翘曲变形量越小。最佳工艺组合为:厚度比0.96∶1,内层(ABS层)成型阶段熔体温度240℃、保压压力80 MPa以及保压时间6 s,外层(PMMA层)成型阶段熔体温度260℃、保压压力50 MPa以及保压时间6 s。优化后得到的总翘曲量为1.435 mm,相比优化前翘曲量降低了69.7%。

Taking an automobile B-pillar exterior panel plastic parts consist of polymethyl methacrylate(PMMA)and acrylonitrile-butadiene-styrene plastic(ABS)as the research object,the thickness ratio,melt temperature,holding pressure and holding time as the influencing factors,Taguchi orthogonal test design was carried out combined with the pseudo horizontal method,the test data was simulated based on Moldflow software,and range and variance analysis for processing on the test data was carried out.Finally,the best combination scheme of two-color injection molding process was obtained.The results show that thickness ratio is the most important factor affecting the value of warping deformation,followed by holding time,holding pressure,and finally melt temperature.Under the condition that the total thickness is unchanged,changing the thickness ratio of PMMA/ABS can change the value of warping deformation produced by plastic parts.The thinner the thickness of the first injection is,the larger the value of warping deformation is,and the value of warping deformation is the smaller when the thickness ratio is closer to 1.The optimal process combination is as follows:thickness ratio 0.96∶1,melt temperature 240℃,holding pressure 80 MPa and holding time 6 s in the forming stage of inner layer(ABS layer),melt temperature 260℃,holding pressure 50 MPa and holding time 6 s in the forming stage of outer layer(PMMA layer).The total value of warping deformation obtained after optimization is 1.435 mm,which is 69.7%lower than that before optimization.