| The multi-layer hot press used in plywood production has the problem of uneven heating temperature of the hot press plate,and the uniformity of temperature distribution on the surface of the hot pressed plate has a direct impact on the mechanical property quality of the finished plywood.To address this problem,this thesis adopted the method of combining theoretical analysis with experimental research and simulation,taking the BY21-4×8/800 multi-layer hot press used by Guangdong Renhua Aoda Plywood Company Co.,Ltd.as the research object.The heat transfer mechanism of hot pressing,the influence law of internal flow channel structure of hot pressing plate on the temperature distribution of plate surface,and the influence of the temperature distribution characteristics of plate surface on the quality of finished product were comprehensively investigated,then the internal structure of the hot pressing plate was improved and optimized.The main research contents and conclusions of this thesis are as follows:(1)The surface temperature distribution of the hot press plate of the existing structure and investigate the influence law of the internal flow channel structure of the hot pressed plate on the temperature distribution on the surface of the plate,the thickness temperature distribution of the slab during hot pressing were measured,and the influence of the temperature distribution characteristics of the surface of the hot pressed plate on the heating of the slab was investigated;the mechanical properties of the finished plywood and analyze the influence of the temperature field of the surface of the hot pressed plate on the performance of the finished product were tested.The experimental test results showed that the surface temperature difference of the hot press plate was 7.4 ?,and the overall temperature of each thickness layer of the slab at the high temperature area of the hot press plate was higher than that at the low temperature area,and the performance parameters of the finished products at different locations differed greatly.(2)According to the influencing factors of the surface temperature distribution of the hot press plate,three kinds of improvement schemes of the internal flow channel structure of the hot pressed plate were constructed,and the numerical simulation method was used for modeling and temperature field simulation analysis.The results showed that the uniformity of the plate surface temperature distribution and the overall heating speed of the three improved structures have been significantly improved,among which the temperature difference of the hot press plate with transverse openings and two inlets and two outlets has decreased by 5.2? compared with the existing structure,and the temperature distribution of the platen is the most uniform,which is determined as the optimal improved solution.(3)According to the improvement solution,the hot pressed plate was tested and installed,and the temperature distribution characteristics of the surface of the improved hot pressed plate,the temperature gradient distribution of the hot pressed plate and the physical and mechanical properties of the pressed products were measured.The results showed that the temperature difference on the plate surface is reduced by 5.6? after the structure improvement,the temperature distribution of the slab at different positions during the hot pressing process is consistent,and the mechanical properties of the hot pressed products are significantly improved and reach the qualified standard and the properties at different positions are stable and consistent.The improvement solution proved to be reasonable and effective.Comparing the experimental and simulation results,the difference between the experimental test value of the hot plate surface temperature difference before and after the improvement is 5.6?,the simulation value difference is 5.2?,and the error is 7.3%,indicating that the simulation model and numerical calculation method are accurate. |
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