Structural Design And Experimental Study Of A New Type Of Air-suction Precision Seed-metering Device For Maize

Corn is of great significance for solving the problem of food security.Due to the large population base in China,the arable land resources were very limited.However,the traditional manual seeding method not only wastes a lot of seeds,but also takes a lot of time and energy to interplant seedlings.Therefore,high-speed precision seeding technology has been applied.Precision sowing technology can effectively save seeds and provide a good environment for the required fertility,water resources and air availability of seeds.Compared with traditional seeding method,precision seeding technology is more convenient,faster and more efficient.The performance of seeding device affects the quality of seeding operation.At present,there are two kinds of seeding device:pneumatic seeding device and mechanical seeding device.Mechanical seed metering device had high requirements for seeds and was not suitable for high-speed operation.However,pneumatic seed metering device had low requirements for the external size of seeds,low seed injury rate and was suitable for high-speed operation.In this paper,a new type of seed ejector was designed by improving the structure of pneumatic seed ejector.The work and conclusions of this paper were as follows:（1）Improving the traditional circular pneumatic seed tray structure,design a new type of seed tray structure with a hole,to facilitateing filling and planting.（2）By measuring and analyzing the physical characteristics of corn seeds,such as three-dimensional size,density,moisture content and 1000-grain weight,the average three-dimensional size of the seeds was obtained,which provided the design basis for determining the size of seed plate-type hole.（3）Theoretical analysis was carried out on the working area of seed platter to analyze the stress situation of corn seeds in the seed filling area and establish the mathematical model of the new type of seed platter.（4）Under the conditions of different negative pressure and rotating speed,the seeding plates with four different air outlet radii were tested.The test results showed that the seeding performance was good when the negative pressure was low and the air outlet radius of the seeding tray was r₄,and the replay rate was low,but the seeding leakage was large,and the overall performance was good when the negative pressure was-1.6kpa.In low-speed operation,the qualified index of air outlet radius r1 was the highest,but with the increase of rotating speed,the qualified index of air outlet radius r₄ increased,while the qualified index of r₁decreased.（5）Determine the best performance of the seed tray.It can be seen from the test that theoverall performance was the best when the outlet radius of the seeding tray was-1.6kpa and the seeding shaft speed was 27.70r/min and the seeding bed belt speed of the seeding device was8km/h.Finally,the seed platter with outlet radius r₄ was selected as the best one.The experimental results showed that the seeding tray had good filling performance,high qualified index and no serious seeding leakage.