Numerical Simulation And Experiment Of Crank Link Organizaton Vibration Screener Based On Discrete Element Method

In agriculture,the grain cleaning is an important content.The grain cleaning screen is an important part of the grain cleaning device.The performance of the grain cleaning screen directly affects the overall performance of the cleaning device.With the development of simulation technology and the improvement of computer performance,using the modern design theory to analyze and study the cleaning device for clearing devices systematically has received more and more attention.In this paper,the vibrating screen of grain cleaning device is taken as the research object,and the motion process of the granular material in the vibration box under different working parameters(amplitude,vibration frequency,screen inclinations,etc.)is tested and simulated.The influence of the screen surface structure(mesh shape,opening rate of the screen surface)and the shape of the screened material on the screen effect was simulated.The main research works include:(1)First,on the basis of the structure of grain cleaning devices used by some scholars at home and abroad and the structure features of several major grain combine harvester in my country,a combine harvester grain cleaning device test device was designed and processed,and the structure of many parts of the grain cleaning sieve has been innovated,and the size parameters of the grain cleaning sieve have been determined through motion simulation analysis and testing.The device has the characteristics of simple structure,convenient installation and debugging,real-time adjustable parameters and the like,and can largely simulate the working process of the grain cleaning device and the movement state of the threshed materials in the grain cleaning device.(2)DEM simulation tests were performed on the motion process of the short threshed materials in the vibrating box under different working parameters.The reliability of the discrete-element simulation model and parameters was verified from both qualitative and quantitative aspects by the bench test.The particle motion of the short threshed materials in the vibrating box was simulated under different working parameters of the vibrating screen.The influence of different working parameters on the vibration motion process was analyzed.The test results show that the amplitude and frequency have a great influence on the particlemotion state on the vibrating screen,and the change of screen inclinations is relatively small to the motion state of the material.(3)Under the condition of not considering the wind field,DEM simulation study was conducted on the effects of different factors of screen surface structure(different mesh shapes,different opening percentage of screening surface)and different material shapes on the screening effect.The motion of the material on the screen surface was studied.The tests showed that the sieve efficiency of the round-hole screen is slightly higher than that of the square-hole screen in the steady state when the opening rate of the screen surface is the same.When the opening percentage of the screen surface is below 60%,the opening percentage has a significant effect on the screening efficiency.On the contrary,the effect is smaller;in the case that the number of grains of wheat-shaped,corn-shaped,and soybean-shaped particles are all equal.The particle shape has a great influence on the screening effect,in which the wheat-shaped particles have the best screening effect,the corn-shaped particles have the lowest screening effect,and the shape of the mesh has a greater influence on the screening effect of the materials.The sifting efficiency of the granules on the square-hole sieve is significantly higher than the sieving efficiency on the round-hole sieve.Among them,the sieving of corn-shaped granules has the greatest impact,and the soybean-shaped granules have the smallest influence.