Simulation Analysis Of Screening Process Of ZL-2 Model Combine Harvester Based On 2D DEM

This paper reviews studies of screening and problems, then develops a two-dimensional(2D)software of vibrating screen which is based on DEM. Using the software can analyze the percent through screen and the screening efficiency by changing the CAD model, the soybean model and simulation parameters. Compare the simulation results to the experimental results looking forward to establish a novel method to the research and optimization of vibrating screen. The main work and results of this paper are as follows:(1)The modeling method of vibrating screen:①Using the principles of mechanism and the plane geometry we can build the model of vibrating screen and solve it. We can obtain the displacement and the velocity of any point in baffle and the sieving medium.②Compile program of vibrating screen and integrate it into the discrete element software which is homemade.③Introduce the idea and the interface of the extraction of the bars.④Increase the screening statistical function which is used to calculate the percent through screen and the screening efficiency.(2)The bench tests and the results:①Design the vibrating screen bench ZDS-1 and choose the proper sieve plate.②The speed of the crank is calibrated.③Measure the triaxial dimension and the single seed weigh.④Bench test results are as follows:When the frequency of the frequency converter changes, the percent through screen is almost unchanged and the percent through screen is changed greatly. When the frequency is 13.0Hz, the screening efficiency is lowest. When the frequency is 12.5Hz, the screening efficiency is highest. That is nearly a parabola.When the areas of sieving medium are not the same, the percent through screen is almost unchanged. Only when the area is 300mm×400mm, there is a sudden drop. When the area of sieving medium is small, the screening efficiency is high. When the area of sieving medium is big, the percent through screen is low. When the angles of sieving medium are not the same, the percent through screen is almost unchanged, between 97% and 98 %. When the angle is small or big, the percent through screen is low. When the angle is not small or not big, the screening efficiency is high. That is to say, only when the angle of the sieving medium is in a certain range, the percent through screen will be high.With the length of the latter hanger is increasing, the percent through screen is becoming bigger but changing slightly, between 97% and 98 %. With the length of the latter hanger is increasing, the screening efficiency is becoming smaller. But the gap of the screening efficiency is very small, when the lengths of the latter hanger are 250mm and 280mm.(3)Simulation and analysis of the screening process of two-dimensional discrete element, and its contents are as follows:①Build the model and choose the microscopic parameters.②Compare the simulation results to the experimental results, the conclusions are as follows:When the frequency of the frequency converter changes, the simulation curves and the expermental curves are nearly coincidence. When the frequency is 13.0Hz, the percent through screen is lowest. When the frequency is between 12.0Hz and 12.5Hz, the screening efficiency is highest.When the angle of the sieving medium changes, almost all the screening efficiency is 97%. When the angle of sieving medium is 20°, the screening efficiency of experiment is 80%, lower than the simulation result. When the angle is 10°and 15°, the screening efficiency is higher. When the angle is smaller than 10°or bigger than 15°, the screening efficiency is lower.When the length of the latter hanger changes, the simulation curves and the expermental curves are nearly coincidence. When the length of the latter hanger is shorter than 280mm, the screening efficiency is increasing with the length of the latter hanger becoming longer. When the length of the latter hanger is longer than 280mm, the screening efficiency is decreasing with the length of the latter hanger becoming longer. The screening efficiency is between 97% and 98 %. The percent through screen is decreasing with the length of the latter hanger becoming longer, between 93% and 77 %.Whth the area of the sieving medium increasing, the screening efficiency is decreasing from 98.6% to 96.6%. When the area of the sieving medium increasing is 300mm×400mm, the percent through screen is highest.The bigger the area of sieving medium is, the more blocked holes you will see.③We can deaw the conclusions that when the frequency is 12.0Hz~12.5Hz, the angle of the sieving medium is 5°~ 10°, the area of sieving medium is 300mm×400mm, the length of the latter hanger is 220mm, the screening efficiency is highest.