Process Optimization Of Volume Pulsatile Injection Molding For PET Bottle Preform

Since having high rigidity,high strength,dimensional stability,light rubbing,light weight and other excellent properties,the PET bottle are favored by more and more consumers,people demand for PET bottle will increasing.In order to improve the production efficiency of PET preform injection molding,we often use the multi-cavity mold.However,in the process of multi-cavity injection molding,there is a phenomenon of flow imbalance.The flow imbalance will result in differences in the quality of the perform.Introducing the volume pulse force field into the whole process of injection molding is a pioneering work in the history of polymer processing.Therefore,it is great significance to promote the popularization and application of the volume pulsation molding technology that explore the effect of flow balance on volume pulse force field and optimize the molding process parameters after introducing the volume pulse force field to improve the quality of the injection molded products.This paper analyzes the mechanism of the flow imbalance in the multi-cavity mold.Through the analysis can know that the major cause of the unbalanced flow in the balance the flow channel is shear induced and the volume pulsation can improve the balance of flow.This paper select melting temperature,injection pressure,injection speed,packing pressure,holding pressure time and V/P switch position as the influencing factor.The difference between the weight of the PET bottle preform were used to measure the flow balance.The experimental results show that the most important process parameters included injection pressure,packing pressure,melt temperature,V/P switch position.This article select the injection pressure,packing pressure,melt temperature,V/P switch position,vibration amplitude and vibration frequency as the influencing factor.PET bottle weight difference as optimization objective to measure the flow balance.Then having Taguchi design experiments.Obtaining the optimum process parameter combination under the vibration force field,and the optimum combination of process parameters is experimentally verified.The experimental results show that the optimized quality of the molded product is stable and the dimensional change is small.It is proved that the vibration force field can improve the balance of the flow in the multi cavity.In this paper,the samples were subjected to DSC test on the vibration injection molding,and It is found that volume fluctuation molding can improve the crystallinity and grain refinement of the material.It shows that dynamic injection can not only improve the balance of mold filling,but also improve the performance of products.