基于可视化的型坯拉伸吹胀模式的研究

Study on Types of Preform Growth in Stretch Blow Molding Based on Visualization

在型坯再加热条件不变的情况下,通过全透明模具和数码摄像机研究了两步法拉伸吹塑中拉伸与吹气的时序(即预吹气延迟时间t0)对型坯拉伸吹胀模式的影响。研究表明,t0是影响拉伸吹胀模式的一个关键因素,随着t0 的增加,型坯预先被拉伸的轴向长度也增加,这时瓶肩的厚度减小,瓶底的厚度增大。实验观察到型坯的拉伸吹胀存在海豚型、积沙型和截圈型3种模式。以海豚型模式成型时,型坯在轴向和径向同时得到充分地拉伸,成型瓶壁厚分布最合要求,积沙型次之,而以截圈型得到的瓶子不合要求。

Preform growth mode in injection stretch blow molding （ISBM） has great influence on the quality of formed bottle. Under the same reheating conditions, the influence of time sequence of stretch and blowing （characterized with delay time to） on the preform growth in stretch blow molding （SBM） was studied using a transparent mold and a digital camcorder. As t0 increased, the stretched axial length of preform increased before blowing, which made the thickness of bottle neck decrease and the thickness of bottle bottom increase. Three types of the preform growth known as dolphin, sandpile, and ring wrinkle were observed. For the dolphin type, the wall thickness is properly distributed, as the preform is sufficiently stretched both longitudinally and radially. The sandpile type gives fair results and the ring type is poor.