Study Of Sieving Process Of Combined Rotary Screen

With the development of the grain industry,the scale of all kinds of grain reserves and grain processing enterprises at home and abroad is expanding day by day,and the processing capacity of grain storage,transportation and processing is increasing,and the combined cleaning equipment has also developed rapidly in recent years.At present,various combinations of cleaning screens have been widely used in the cleaning process necessary for the storage and processing of various grains.Its design is designed to realize the integration,high efficiency and automation of the cleaning process.Its performance and reliability directly affect the work efficiency of the whole grain warehousing and processing process.There are some problems in the existing combined cleaning screening at home and abroad,such as high energy consumption,insufficient output,and the cleaning effect needs to be improved,so the experimental research and optimization design of the combined cleaning equipment is of great significance to the development of the food industry.This paper studies the motion of combined rotary sieve,through theoretical analysis and dynamic simulation,we study the screening process,studies the influence factors of screening performance,obtains the optimal screening parameters and screen size,and provides guidance for the optimal design of combined rotary sieve.The main research contents of this paper are described as follows:(1)In order to meet the requirements of large yield and high efficiency of grain cleaning,a new type of combined rotary sieve is designed to establish the dynamic model of the combinatorial rotary sieve system by using the kinetic theory of rigid and flexible coupling.The second type of Lagrangian equation is applied to establish the dynamic equation of the combined sieve sieve system,derive the steady state kinetic equation of the sieve and the bending vibration equation of the boom,and obtain the natural frequency calculation method of the system,so as to explore the influencing factors and the influence of the working parameters on the movement of the sieve.According to the screening principle of the material and the motion analysis of the sieve body,the theoretical calculation method of the limit speed range of the sieve body is obtained.(2)Establish the virtual prototype model of the combined rotation screen based on Adams software,and obtain the movement track of the marked points on the sieve body.The analysis of the sieve body shows that the movement track of the sieve body is close to the positive circle line,and the radius of the positive circle radius is the rotation radius of the sieve body.The influence of speed and block mass is consistent with the theoretical analysis.At certain eccentric distance,the block mass has a positive linear relationship with rotary radius;the sieve speed and rotary radius are not significant linear relationship,showing a negative correlation in a certain range.The results of theoretical analysis and virtual simulation are verified by the corresponding combined sieve test.(3)Analyze the force motion of the material particles on the sieve surface to obtain the motion velocity equations and trajectory equations of the particles.The motion speed and trajectory of single particles on horizontal and inclined sieve surface and the reliability of wheat sieve simulation.To simulate the motion of the sieve system,the influence of the sieve flow,the rotation speed,the rotation radius and the screening inclination angle.The screening efficiency decreases with the increase of the sieve flow,the rotation radius and the sieve surface inclination.When the rotation speed is 480 r/min,the screening efficiency decreases with the increase of the sieve flow and the rotation radius,and the material flow speed increases with the increase of the rotation radius,the speed and the sieve surface inclination,without being affected by the sieve flow.Comprehensive analysis: the screening flow is 3.0t/h,the rotation speed is 420～480 r/min,the rotation radius is 20～25mm,the screening surface inclination is 8° can get the better screening effect.(4)Based on EDEM software,the screening process of large and small miscellaneous screening surface was simulated,with three screening parameters of rotation speed,rotation radius and inclination of screening surface as test factors,and material extraction rate,impurity removal rate and flow speed as three evaluation indexes of screening performance.Through the single factor test,it is found that improving the rotation speed,rotation radius and the screen inclination can accelerate the material flow speed and improve the screening processing capacity,but the material extraction rate and the removal rate of materials also decrease accordingly.Orthogonal tests are used to analyze the influence of screening parameters on the screening performance,and the comprehensive influence of each parameter on the screening performance is: rotation speed>rotation radius>screen inclination.The optimal parameter combination is obtained by matrix analysis: rotation speed is450r/min,rotation radius is 22 mm,and the screen inclination is 9°.