降低PET碳酸瓶成型压力的瓶底模结构优化及实验研究

Optimization and Experiment of Bottle Bottom Mold Structure to Reduce the Molding Pressure of PET Carbonated Bottles

针对五爪瓣型的聚对苯二甲酸乙二醇酯(PET)碳酸瓶底在吹塑过程中成型困难的问题,提出一种改进的底模结构,以降低最低吹塑压力。利用Polyflow软件有限元分析,研究了碳酸瓶底的不同几何特征对于吹塑成型中材料流动性的影响,并获得瓶底厚度分布的点云数据。使用ABAQUS仿真非均匀壁厚的瓶底力学性能,在保证一定瓶底性能的前提下,对原瓶底结构进行优化设计。以2 L雪碧瓶为例设计测试底模进行实验,测试的最低吹塑成型气压由原底模的24 kg/cm^(2)降低为20 kg/cm^(2),且在凸底测试中,3组测试样品的72 h底中心高度最低为2.52 mm,高于要求的标准0.5 mm。

Polyethylene terephthalate(PET)carbonic acid bottle with five claw flap was difficult to be formed in the process of blow molding,because of its special bottom surface structure.An improved bottom mold structure was proposed to reduce the minimum blow molding pressure.Polyflow finite element software was used to study the influence of different geometric characteristics of carbonate bottle bottom on material fluidity in blow molding,and the thickness field of bottle bottom was obtained.ABAQUS was used to simulate the mechanical properties of the bottle bottom with non-uniform wall thickness,and the original bottle bottom structure was optimized under the premise of guaranteeing certain bottle bottom properties.Taking 2 L Sprite bottle as an example,the sample of bottom die was designed for the experiment.The lowest blow molding pressure of the test was reduced from 24 kg/cm^(2) to 20 kg/cm^(2).In the convex bottom test,the minimum height of the center of the bottom of the three groups of test samples was 2.52 mm at 72 h,which was higher than the required standard of 0.5 mm.