Optimization and experiment of seed-filling performance of the air-suction densely planted seed-metering device based on DEM

Abstract

Aiming at the problem of lower single granularity and uniformity of the existing air-suction seed-metering device under the condition of densely planted crops according to the agronomic requirements of soybean-maize strip intercropping mode, the disturbing effect of seeds on the seed-filling performance was studied to improve the seeding performance of the seed-metering device under the condition of high speed. Based on the theory of discrete element method (DEM), taking the air-suction seed-metering device designed for both soybean and maize as a model and maize variety of ‘Zhengdan 958’ suitable for densely planted as the research object, the DEM single-factor test was conducted on the influence of the structure, position, and number of bosses on disturbing performance with the average kinetic energy, average velocity, and average normal force of seeds as evaluation indexes. The results showed that the disturbing performance of seeds was better when the boss structure was D-type, the diameter of the base circle where bosses located was 160 mm, and the number of bosses was 13. To further improve the structural parameters of the D-type boss, the primary structural parameters, such as the side length and arc radius, were simulated by a single-factor test. The position, side length, and arc radius of the D-type boss were further optimized and verified using central composite design (CCD) based on the results of the single-factor test. The CCD results showed that the average kinetic energy of seeds was 7.39 × 10⁻⁷ J, the average velocity was 4.53 × 10⁻² m/s, and the average normal force was 6.18 × 10⁻² N when the diameter of the base circle where bosses located at 159.865 mm, the side length and arc radius of the D-type boss of 5.690 mm and 5.476 mm, which significantly enhanced the disturbing performance of the seed-metering device. The optimized boss structures and parameters of the seed-metering device were validated with an all-factor test of working speed and working pressure. When the working speed and working pressure were 4 ~ 6 km/h and 7 ~ 7.5 kPa, the qualified rate was 94.75% ~ 97.49%, the multiple rate was 0.92% ~ 1.43%, and the leakage rate was 1.59% ~ 3.82%, all of which were substantially lower than the original one. Therefore, the seed-filling performance of the seed-metering device will be improved by increasing the disturbance of seeds to a certain extent.