| In the era of rapid development,with the continuous growth of population,the problem of food security has been paid attention to.As one of the important food crops,corn is gradually increasing with the development of breeding industry and industry.Its planting income is considerable,farmers have high enthusiasm for planting,and the planting area is wide.However,the single yield is lower than that of foreign developed countries,and there is a lot of room for improvement.Precision sowing technology is an important technology It is one of the ways to increase production.The structure and transmission system of the traditional one device one row seed metering device are more complex,and the seed metering device fixed on the seeding unit will affect the seeding qualified index due to the vibration of the machine and other factors.Based on the analysis of the existing precision seed metering device,a new type of batching roller seed metering device with positive pressure was designed,The main research contents are as follows:(1)The shape characteristic parameters of corn seeds were measured to provide theoretical basis for the design of seed metering device.Based on the working principle of positive pressure disturbing seed,filling seed,carrying seed and sending seed,the overall structure and dimensions of each part of seed metering device were determined: diameter of batching roller315 mm,diameter of 5.5mm,number of holes 58,overall dimension of seed cleaning scraper and angle of inclined plane,width of seed filling flow bed screen 44 mm.The static analysis was carried out on the seed capturing stage,the seed pressing stage and the seed cleaning process in the seed filling process of the seed metering device.The relationship between the performance of the seed metering device and the characteristics of the seed itself,the diameter of the mold hole,the seed filling pressure,the diameter of the batching roller and the rotating speed was obtained.The installation angle of the seed cleaning device was determined to be 5 ° to 38 ° and the installation angle of the seed filling flow bed was 16 °.(2)CATIA is used for 3D modeling and structure optimization of parts assembly.Small assemblies are assembled into seed metering assembly for structure optimization.3D printing technology is used to produce more complex parts.Simple parts are machined and assembled.Through the single factor bench test of disturbing air pressure,filling air pressure and working speed,it is concluded that disturbing air pressure is 2.7～3.1kpa,filling air pressure is 3.5～5.5kpa,and the qualification index is better in 4～12km/h.The regression model and equation of seeding performance were established and analyzed by quadratic orthogonal rotation test and design expert 8.0.6.The results showed that the qualified index was more than 95% when the disturbing air pressure was 2.9kpa,the filling air pressure was 3.9～5.5kpa and the operating speed was 4～12km/h,and the heavy leakage index was better than the national standard.The results show that the qualified index is 98.51%,the replaying index is 0.34%,and the missing sowing index is 1.15% under the conditions of optimal working speed of 10.30km/h,seed filling pressure of 4.83 kpa and seed disturbing pressure of 2.9kpa.(3)The field test of seed metering device was carried out under the conditions of working speed of 10.0km/h,filling pressure of 4.5kpa and disturbed seed pressure of 2.9kpa.The results showed that the qualified index was 97.91%,replaying index was 0.26% and missed sowing index was 1.83%.The results were better than the national standard,which was of great significance to increase the yield per unit of corn. |
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