Design and Experiment of Air-Suction Maize Seed-Metering Device with Auxiliary Guide

Due to the irrational design of the seed discharge plate and the vacuum chamber, the high-speed seed filling effect of the air-suction maize precision seed-metering device is poor. Therefore, an air-suction maize seed-metering device with an auxiliary guide is designed to realize high-speed precision seed discharging. An auxiliary guide filling theory is put forward, and the design of the seed plate type hole charging structure is formulated. Fluent 2022 software is used to analyze nine kinds of vacuum chamber structures; the optimal vacuum chamber structure parameters were determined by polar analysis. In order to investigate the changes of negative pressure and flow speed under the dynamic flow field, a slip grid was used to analyze the dynamic flow field with three different operating speeds and negative pressures. It found that the size of negative pressure did not affect the flow field distribution, and the pressure and flow speed gradually decreased as the distance from the inlet was farther away; meanwhile, the negative pressure distribution and air speed distribution were almost unchanged when the holes at different rotational speeds were at the same position. Finally, bench tests were carried out, and three indexes, namely, the qualified index, the multiple index and the missing index, were selected, with operating speed and negative pressure as factors, two-factor five-level orthogonal test was carried out, and the optimal parameter combinations at 6.0, 7.5, 9.0, 10.5, and 12 km/h forward velocity were derived and verified by regression equations. The results showed that the designed seed-metering device was repeated five times when the pressure of the vacuum chamber was -3.5 kPa and the rotational speed of the seed-metering device was 23 r/min, the average grain spacing qualified index was 95.8%, the missing index was 1.6%, the multiple index was 2.6%, and the indexes met the requirements of precision sowing. It is of great significance for our country's seeder to develop in the direction of high-speed and precision.