Study On Screening Mechanism Of Wet Sand Particles And Characteristics Of Disc Spring Vibrating Screen

With the rapid development of urbanization in China,the demand for sand and gravel materials in the market is also increasing.Sand screening is an important link and key technology in sand making industry.The wet sand screening process has occupied the mainstream position in the domestic sand making industry.However,there is little research on the wet sand screening process,and its screening mechanism is not clear.In addition,the number and radius of filled balls in the process of non spherical wet sand discrete element modeling,inter particle contact model and parameter setting have not been studied in detail.Furthermore,there is no effective way to solve the problems of high energy consumption and low reliability faced by the large-scale vibration screening equipment.In view of the above problems,through discrete element method,finite element method and machine learning,this paper focuses on the modeling and calibration of non spherical wet sand and stone particles,the research on the screening process and mechanism of wet sand and stone particles,the optimal design of screening parameters by machine learning,the dynamic characteristics of the new disc spring elastic system and its application in elliptical vibrating screen,The main research contents are as follows:In order to obtain a more accurate model of non-spherical wet sand and gravel particles,the JKR contact model and multi-ball filling method were used to model sand and gravel particles of different shapes.First,the significant influencing factors of the tangent of the accumulation angle were found to be the surface energy and the coefficient of dynamic friction through the cylinder lifting experiment.Then the surface energy and dynamic friction coefficient were optimized through the steepest climbing experiment.The optimal surface energy and dynamic friction coefficient were used in the screening efficiency simulation to optimize the filling sphere radius of the wet sand particles.The optimal particle discrete unit models of different shapes of sand and gravel particles were obtained.To study the screening mechanism and influencing factors of the wet sand and gravel particles on the elliptical vibrating screen,the discrete element method was used to simulate the wet sand and gravel screening process,and the movement process of the particle group on the screen surface was observed.The screen position was analysed and the layering mechanism of wet sand and gravel particles were explained.Meanwhile,the control variable method was used to analyze the influence of varied factors on the screening efficiency and screening time and the significant influencing factors were selected.In order to obtain screening parameters with high screening efficiency and short screening time,the support vector regression machine optimized by the gray wolf algorithm was used to establish the screening parameter model,and the learning of the model is improved through the radial basis kernel function.Then the Gray Wolf Optimizer was used to optimize the model.The optimal screening efficiency and screening time were obtained and verified by discrete unit simulation.Aiming at the problem that the traditional elliptical screen requires too much excitation force and the working state of the resonant screen is unstable,a disc spring elastic system was designed as a new excitation element.Using numerical analysis and finite element method combined with dynamic experiment,the natural frequency,mode shape and amplitude of the disc spring elastic system were studied.It was found the resonance could be used to amplify the amplitude by disc spring elastic system and showed good mechanical linearity.In addition,the effects of constraint conditions,the number of disc springs and assembly conditions on dynamic performance were also explored.In order to study the performance and dynamics of the disc spring vibrating screen,the dynamic characteristics of the disc spring vibrating screen were analyzed and tested by numerical analysis method and finite element simulation.Comparing the changes in the trajectory of the screen surface and the analysis of the screening process,it was found that the disc spring vibration show better screening performance with the wet sand and gravel particles,which has the advantages of low energy consumption and strong reliability.