The Design And Tests Of Tilt Dise-type Fine And Small-amount Seed-metering Device For Small Grain Seeds

To solve the difficult problems of sowing for small grain seeds, according to the agronomic requirements for fine and small-amount sowing, I design and manufacture a tilt dise-type fine and small-amount seed-metering device for small grain seeds. According to the national standard, I design experiments to test the performance of this device. The main research contents and conclusions are as follows:(1) Research the physical and mechanical property of small grain seeds, thus providing parametric supports for the structural design for this device. Use YP502N electronic scales to measure the thousand kernel weights, and analyze them, dimension datum, hardness values and friction coefficients with 6 kings of materials of 8 kinds of small grain seeds.(2) Design the structure size for components and parts of this device. This device is mainly consist of seed-metering device, bevel gear assembly, supports, baseboard, driving motor, governor, switch and mobile power. The seed-metering device is mainly consist of seed case, seed-filling dise, shell, seed-discharging dise, elastic flipping device, drive shaft. Take millet as a example, according to the agronomic requirements for fine and small-amount sowing for millet, shape and dimension of millet, after analyzing the millet's motion in this device, I design the structure of the seed case and the adjustive spile to adjust the amount of entered seeds from the seed case to the seed-filling room. There distribute 36 seed-filling holes in the circumference of the seed-filling dise uniformly. I design the structure size of the seed-filling hole. The diameter of the seed-filling dise is 140mm. There is an impurity containing groove in the edge of the seed-filling dise to avoid the impurity to damage the surface of this device. The diameter of the seed-discharging dise is 140mm. Corresponded with the seed-filling holes, there are 36 seed-discharging grooves. The groove is a U-type groove, and its width is 4mm, and its depth is 3mm, and the intersection angle between the center lines and them is 20°. The seed-filling dise is above the clapboard of the shell, and the seed-discharging dise is below the clapboard. There are 2 rolling bearing installed in the clapboard. The two dises are located by the two rolling bearings and the shoulder of the drive shaft. The fit clearance is 0.2mm between the two dises and the clapboard formed by their boss structures, and the fit clearance is also 0.2mm between the circumferential profiles of the dises and the shell, thus avoiding friction. Design the shape and dimension of the seed-passing hole by analyzing the motor of millet in the shell. There is a impurity-passing hole in the lower end of the clapboard to discharge the impurity. The seed-dropping hole is on the lower end of the shell, and the opening angle is 16°. I also design the structure of the drive shaft, the elastic flipping device to flexibly flip the seeds out of the filling holes, and the forms of the joint, fixation and installation, etc.(3) According to the national standard requirements 'Testing methods of sowing in lines' and 'Testing methods of single seed drills (precision drills)', I design and conduct the steadiness of sum total seeding experiments and uniformity of seeding experiments to test the performance of this device. Take millet as a example, the percentage of damaged millet is less than 0.04%, and the variable coefficient of steadiness of sum total seeding is less than 0.7%, and the qualified index of hill spacing is greater than 86%, and the over-sowing index is less than 12%, and the miss-seeding index is less than 7%, and the variable coefficient of qualified hill spacing is less than 5%. All the indexes meet the industrial standard requirements'Grain drill-Part 1:Specifications' and 'Specifications for single drills (precision drills)'.