| A small-spacing dense-planting air-suction precision metering device with double seed clearing effect that can sow soybeans,corn,and other crops is designed to improve single seed sowing and uniformity of the metering device under dense planting conditions and to meet the agronomic requirements of soybean-corn strip compound planting technology.The structural parameters and operating parameters of the seed-metering device are established through the design of critical components,theoretical analysis,discrete element simulation,and bench testing.The following are the primary research findings:（1）The seed-metering device is primarily made up of a front shell,a seed baffle,an internal and external seed cleaning knife,a seeding plate,a negative pressure chamber,and a rear shell for the design of the structural parameters.The seed-metering disc,the inner and outer cleaning knives,and other major parts of the seed-metering device are initially created.The seed-metering disc,the inner and outer cleaning knives,and other major parts of the seed-metering device are initially created.The seed-metering disc has a diameter of 220 mm,the hole’s base circle has a diameter of 190 mm,the soybean seed-metering disc has a diameter of 3.5 mm,and the corn seed-metering disc has a diameter of 4.5 mm.The adjustment range of the outer clear seed knife was found to be0～8 mm,and the adjustment range of the inner clear seed knife was found to be 0～2.4mm,using the appropriate three-axis dimensions of Zhonghuang 39 soybean seeds and Zhengdan 958 corn seeds.（2）The number of holes in the seed-metering plate was counted using the orthogonal test and central composite test,and the number of holes was divided by the external and interior clearance distance.It was determined that 35 holes in a head of corn were the ideal amount.The qualified index was 95.45%,the replay index was 1.3%,and the missed index was 3.25%when the external clearance distance was 6.2 mm and the interior clearance distance was 1.6 mm.The highest number of holes for soybean seeding was 62.The qualified index was 97.16%,the replay index was 0.05%,and the missed index was 2.79%when the outer clear seed distance was 4.1 mm and the interior clear seed distance was 1.6 mm.The qualifying index of corn planting was 95.40%,the replay index was 1.5%,and the missed sowing index was 3.1%when the forecast findings had been validated and verified.The soybean planting qualifying index was 97.78%,the replay index was 0.32%,and the missed index was 1.90%.It demonstrates that the experimental findings and the anticipated optimal working parameter combination are essentially consistent,and the seeding performance index satisfies the seeding criteria.（3）The middle yellow series of soybean seeds were used to design the seed metering plate’s aperture,and it was found that the range of the plate’s aperture was2.9～5.3 mm.The ninth hole sizes on the seed metering plate were spaced 0.3 mm apart.The analysis is done on the typical pressure differential between the positive and negative sides of each working area and hole diameter.It is determined that the pressure loss is lowest when the hole diameter of the metering device is 2.9～3.8 mm based on the pressure loss of each hole diameter in the filling region.The bench test indicates that the ideal soybean aperture is 3.5～3.8 mm,the qualified rate is 97.3%～98.9%,the leakage rate is 0.83%～0.86%,and the replay rate is 0.24%～1.79%.According to the soybean bench test,the seed metering device operates more effectively when the soybean seeding aperture is 3.5～3.8 mm.（4）The base circle diameter of the boss was found to be 159.865 mm,the length of the bottom edge was found to be 5.690 mm,and the arc radius was found to be 5.476 mm by the three-factor and three-level quadratic orthogonal rotation center combination test.It was possible to replicate and confirm the ideal parameter combination.The findings confirmed the predictions,with the population’s average kinetic energy being 7.39×10-7 J,average speed being 4.53×10-2 m/s,and average normal force being 6.18×10-2 N.（5）On the functionality of the metering device,field tests were conducted.The certified rate of corn plant spacing was 82.89%～85.55%when the field working speed was 3～6 km/h,the rate of reseeding was 7.93%～9.26%,the rate of missed sowing was5.19%～9.69%,and the rate of seedlings was 89.59%～93.54%.The qualified rate for soybean was 81.3%～83.8%,the reseeding rate was between 6.98%～8.87%,the missing rate was between 7.33%～11.72%,and the seedling rate was between 84.17%～88.73%. |
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