| The new energy vehicle represented by electric vehicle is an important direction of automobile industry transformation and an important fulcrum for automobile industry of China to achieve leapfrog development.Battery box is the carrier of electric vehicle power battery.Its lightweight level is of great significance to enhance the energy density of power battery pack and the vehicle’s endurance.It has gradually become a research hotspot.Compared with the traditional metal battery box,LFT-D thermoplastic composite battery box has higher strength and obvious weight loss effect,which significantly improves the energy consumption economy of electric vehicles.The manufacturing of LFT-D composite battery box is mainly through adding a certain proportion of reinforcing fibers to the resin matrix to mix and solidify in the die by hot pressing.The final quality of the composite product is largely determined by the molding process parameters,especially the uniformity of the temperature of the die.Based on the manufacturing process characteristics of LFT-D composite materials,this paper focuses on the structural design,die insert design and cooling system design and optimization of LFT-D composite battery box.The main tasks are as follows:(1)Design the upper box structure of composite battery and analyze its static and modal characteristics under typical working conditions.Through analysis,verify whether its mechanical strength meets the requirements of relevant industry specifications.Combined with the manufacturing process of LFT-D composite battery box,analyze and clarify the influence of main process parameters on the product quality.(2)Design the structure and cooling system of splicing die insert for battery box forming and study the heat transfer of insert in typical forming process.According to the multi-ribbed characteristics of the inner wall of the battery box,the lower die splicing insert structure was designed,and the cooling runner structure of the insert was designed.Based on the typical insert structure,the influence of the layout of the internal runner structure on the heat transfer of the battery box and the insert was studied.(3)According to the typical battery box structure and its forming insert,the influence of the structure of water separating sheet and the property of coolant on the heat transfer of the insert and composite melt was analyzed.The effects of different types of water separating sheet structure on the heat transfer between the insert and the composite melt were studied,and the effects of the properties of the cooling fluid on the heat transfer performance of the insert were analyzed according to the velocity distribution of the cooling fluid and the temperature variation of the insert.(4)A heat transfer enhancement model was proposed based on the influence of the layout structure of the cooling runner and the properties of the coolant on the heat transfer of the insert.Based on 3D printing conformal channel theory,a new cooling optimization structure is designed and its cooling optimization effect is quantitatively analyzed.Aiming at the problem of slow cooling speed and uneven temperature distribution,a solution of intensified refrigeration with local semiconductor chillers is put forward.On this basis,a scheme of quench and heating device based on semiconductor refrigeration is further proposed.The characteristics and innovations of this subject lie in the application of LFT-D technology in the design of new upper battery box,the splicing insert structure of LFT-D moulding for upper battery box of electric vehicle is proposed,and the scheme of heat transfer enhancement is put forward based on the analysis of the factors affecting cooling efficiency of the mould.At the same time,the idea of conformal flow of 3D printing and semiconductor refrigeration technology are combined to further improve the heat transfer.A new cooling scheme of die was put forward,which made a positive exploration for the high quality forming of LFT-D battery box. |
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