| Hot runner technology is an advanced technology in the field of injection molding.It has the advantages of improving production efficiency,reducing production cost,improving product quality,shortening production cycle,etc.,and is being adopted by more and more enterprises.In the process of PE caps injection moulding,multi-cavity hot runner moulds are often used.Multi-cavity hot runner injection molds can greatly increase production efficiency and quality,shorten production cycles and reduce manufacturing costs.However,as the number of cavities continues to increase,the structure of the runner plate becomes more complicated,making it more difficult to design and manufacture;at the same time,the mold dimensions become larger,the temperature of mold is difficult to control and the injection pressure becomes larger during injection molding,which easily leads to excessive deformation of mold parts,cracking of the cavity,overflow and leakage of plastic material etc.,and even the mold damage and invalidation.In this thesis,a 32-cavity PE cap mold hot runner system is studied.The research status of injection mold hot runner technology and PE cap injection mold and the injection molding CAE technology were analyzed.Through the analysis of the multi-cavity PE cap injection mold and product structure design,combined with the physical and rheological properties of PE,the reasonable molding process of PE material and the characteristics of PE cap mold are determined.Using a natural balance form,a 32-cavity cap casting system was designed.Based on the data of PE bottle cap,the diameter of hot runner in each layer was calculated,and the physical model of melt in hot runner was established.The Moldflow software is used to simulate the flow resistance and flow balance of the melt in the hot runner,and the corresponding optimization constraints are set to optimize the runner size and make the casting system reach the filling balance.The heating power and heat loss of the runner plate in the hot runner system are calculated,and the temperature distribution and thermal expansion of the runner plate are analyzed to provide a basis for the reasonable distribution of the heater on the runner plate,and the heat balance design of the hot runner system is realized.Finally,the structural design of the hot runner system of a 32-cavity PE cap injection mold was carried out,and the height measurement of the nozzle needle of each hot nozzle,the heating test of the runner plate,the test mode of the mold and the production inspection of the product were carried out.The research results of this thesis can provide certain reference and guidance for the design and optimization of hot runner injection molds for multi-cavity PE caps. |
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