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To satisfy the demands of soybean precision sowing, this article starts with statistics of the physical parameters of soybean seeds in Heilongjiang province, China. The filling process of soybean seeds was analyzed, and the ratio relationship between the diameter, depth, chamfer length of seed-metering wheel's holes and the mean diameter of soybean seeds was determined. EDEM was used to simulate seeding circumstances of hole seed-metering wheel with different holes' sizes. The hole diameter ratio, hole depth ratio, and chamfer length ratio were the test factors, while the percentage of single multiple and the empty seeds were test indexes. The triple quadratic regression orthogonal rotation combination test was designed, and the mathematical model between test indexes and test factors was established. Results showed that the influence of hole diameter ratio and hole depth ratio was significant (p < 0.01) in the case of single, multiple and empty seed percentage while chamfer length ratio was only significant in single seed percentage compared to multiple and empty seeds percentage (p > 0.05). The chamfer length ratio was 0.15, the hole diameter ratio was 1.63-1.73, the hole depth ratio was 0.81-1.20, the quality of seeding index was more than 90, and multiple and missing indexes were less than 6% and 4%, respectively. The soybean hole wheel seeding device was produced under the optimal parameter combination, to perform a comparative verification test with non-optimized parameters. The test showed anastomotic simulation results, verified the validity of the simulation. The seeding device after optimization expressed the best operating performance, which might satisfy the demands of soybean precision sowing. The study results can provide a theoretical reference for the optimization design of soybean seeding devices. [ABSTRACT FROM AUTHOR]

To improve the uniformity of the flow when fertilizer apparatus discharges fertilizer, a kind of fertilizer apparatus owned arc gears was designed. Also, the design and working principle of its general structure and key components were analyzed theoretically. Aiming at exploring the influence of arc structural parameters to the performance of arc gears discharging fertilizer, DEM simulation was used in this study. Fertilizer apparatus owned arc gears was taken as the research object to analyze the influence of two key components including the arc radius of gears' concave-grooves and the minimal length between two mutual meshing gears. The variation coefficient of fertilizer discharging amount stability and the linear determined coefficient of fertilizer discharging amount in unit time as evaluation index were selected. Two factors and five levels quadratic rotation orthogonal experiment was applied, and Design-Expert 8.0 software was used to achieve data processing and analysis. The results of experiment indicated that the arc radius of gears' concave-grooves had significant effect on the linear determined coefficient of fertilizer discharging amount in unit time, and the minimal length between two mutual meshing gears had significant effect on the variation coefficient of fertilizer discharging amount stability. The optimum structural parameters were 8.54 mm as the arc radius of gears' concave-grooves and 5.22 mm as the minimal length between two mutual meshing gears. Upon this circumstance, the variation coefficient was 0.28 and determination coefficient was 0.9972. The optimum apparatus was selected to conduct the bench test and field simulation test. The results indicated that the variation coefficient is 0.27, and the linear determined coefficient of is 0.9980. The results of simulation experiment were anastomotic basically with the real result, which showed that DEM simulation technology was usable to the experiment of testing fertilizer discharging. The results of this research can provide a reference to the improving of performance in discharging fertilizer. [ABSTRACT FROM AUTHOR]