Design and test of a pneumatic precision metering device for corn

To improve the seeding quality of a horizontal plate corn metering device under conditions of high-speed operation of a seeder, a pneumatic precision metering device for corn was designed. Aiming to verify the rationality of the structural design of the seed plate, the seed-filling performance of circular hole (CH), circular hole with chamfer (CCH), tapered hole (TH) and tapered hole with chamfer (TCH) at different rotating speeds and the seed plate thicknesses were compared and analyzed by discrete element orthogonal simulation experiment. The results showed that the best seed-filling performance was obtained for the 6 mm seed plate with TCH hole, and the missing seeding index was 1.57% when the rotational speed of the seed plate was 20 r/min. Four types of seed plates with thickness of 6 mm were tested on the bench to verify the missing seeding index, at the same speed levels with those of simulation analysis, and it turned out that the difference between test result and simulation was less than 10%. To test the seeding performance of the metering device, a double-factor test was carried out at the forward speed of the seeder and the air velocity at the inlet of the metering device. The results showed that the missing seeding index of the metering device decreased significantly with the increase of air velocity at different forward speeds. The optimal air velocity of the fan was 16 m/s, and the air-flow velocity attached to the seeds was 163.84 m/s. The results can provide the guidance and direction for the design and development of precision metering device. © 2020, Asian Association for Agricultural Engineering. All rights reserved.