Abstract:Considering the practical problems that the inadequate seed supply and discharge capacity at high speed operations in the existing mechanical centrifugal metering device for rapeseed which led to mismatch between the amount of seed row and the operation speed, and poor seed row performance, a type of metering device with passive seed filling and “round hole+gradient hole column” combined type holes for seed discharge was designed. The mechanical model of seed supply and discharge process was constructed and the key structural parameters affecting seed discharge performance were analyzed and determined. The experiment on the influence of the seed supply adjustable height on the adjustment range of the seed supply rate was simulated by using EDEM discrete element simulation software, which revealed the seed supply rate was adjustable in the range of 64.95~357.54g/min when the seed supply adjustable height was in the range of 3~8mm. The influence of the hem height and inclination angle of the seed limiting sleeve on the initial seed quantity, critical speed and the maximum height of the annular seed layer was analyzed by using two factors and three levels orthogonal test. The optimum structural parameters of seed limiting sleeve were determined by bench test. Combined with high-speed photography, the relationship between the rotating speed of the moving cone and the seed metering amount under five kinds of hole structures was compared, and the optimal hole structure was determined as “round hole+gradient hole column” combined type holes. The bench verification test results of the metering performance of the metering device with better parameter combination at different rotating speeds showed that when the speed of the metering device was 115~205r/min, the seeding amount rate was 60.96~355.76g/min, the apiece row consistency variation coefficient was less than 5.2%, the single row stability variation coefficient was less than 1.3%, and the damage rate was less than 0.5%, which can meet the working speed of 6~12km/h. The field experiment showed that when the planting speed was 7.89km/h and 11.98km/h, the apiece row plant distribution consistency of rapeseed was less than 11%, and the planting density was 43~58 plants/m2, which could meet the seeding performance requirements of rapeseed.
