Research And Application On Hot Runner System For PET Preform Multi-cavity Injection Mold

In the process of injection molding of PET bottle preform, it is difficult to control the processing conditions for the narrow temperature range of PTE resin. So in the actual production, the hot runner mold was usually used. Especially, multi-cavities hot runner mold can reduce the manufacturing cost and raise the productive efficiency of PET bottle preform. But when the cavity number increased, the structure of hot runner plate would become very complicated and more difficult to design and manufacture; at the same time, the mold dimensions would become very large and the temperature of mold would be difficult to control; In addition, due to the high injection pressure in the processing, it may cause the excessive deformation of mold parts, overflow and leakage of plastic material, cracking of the cavity etc., even the mold damage and invalidation.In this thesis, deformation factor of large multi-cavity hot runner mold of PET bottle preform mold with 96 cavities was researched systematically, and its gating system was also designed. MoldFlow software was used to simulate the filling process in runner system to optimize the runner dimensions, and it also laid a theoretical and practically foundation for the flow balance design. The distribution of temperature field in the mold was calculated by Ansys to solve the periodical quenching and heating of group cavity mold in processing, excessive deformation of mold parts due to high injection pressure, overflow and leakage of plastic material, cracking of the cavity etc. and realize the heat balance of hot runner system. Besides, the runner plate heating test will be experimented.The results of this thesis will provide theoretical basis and guidance for design and analysis of large-scale and multi-cavities precision hot runner injection mold of precise PET bottle preform.