Research On The Drying Characteristics Of Substrate And Optimization Of Air Nozzle Structure For High Precision Coating Suspension Ovens

The oven is an important part of the high precision printing and coating equipment.The substrate finished by printing and coating is dried by hot air in the oven before finalizing its production process.Suspension ovens are widely used in the drying of solar cells,flexible electronic films and other printing and coating applications due to their unique internal structure and non-contact drying method.Due to the special way of contactless drying inside,it is especially important whether the hot air blown by the nozzle can keep the substrate in a stable state of suspension between the nozzles to complete the drying.Therefore,according to the data provided by enterprises,this paper uses the principle of hot air drying combined with the theory of computational fluid dynamics,and analyzes the problem of poor air uniformity existing in the existing oven through numerical calculation simulation,and optimizes the design of the nozzle structure to achieve the improvement of air uniformity of the nozzle,the specific research content is as follows:(1)According to the data provided by the enterprise,the overall model of the suspended oven was established by using the 3D modeling software,and the simulation analysis of the overall structure of the oven was carried out by introducing the RNG k-ε model,and the analysis object was determined as the flow field on the surface of the substrate,and the simulation analysis shows that the hot air provided by the original oven structure has the problems of low and uneven values of air speed and temperature,and large fluctuations of pressure distribution on the surface of the substrate.(2)To address the problem of poor air uniformity of the nozzle in the oven,a simulation model was constructed by introducing the SST k-ω model to simulate the near-wall surface between the nozzle and the substrate,analyzing the distribution laws and effects of different nozzle slit widths and air supply heights on the flow field-related characteristics of the substrate surface,and determining the optimal nozzle slit width and air supply height used in this paper.The results show that the optimized nozzle has better performance when compared with the original nozzle structure.(3)To address the problem of low air speed and temperature values and poor uniformity caused by vortex accumulation in the area between the two slits of the nozzle,the existing nozzle was optimized by adding a pressure relief hole structure at the bottom of the nozzle,and the optimal size of the pressure relief hole design was determined by means of a control experiment.The simulation results show that the optimized nozzle structure has better performance and is more conducive to the drying of substrates.A nozzle test chamber was designed and built to measure the temperature and wind speed parameters of the substrate surface flow field with and without the pressure relief holes to verify the correctness of the simulation results.