Seeding performance experiment of pneumatic-typed precision centralized metering device

Abstract: The rapeseed precision seeding has the advantages of saving labor, time and cost, and high productivity and so on, and the rapes under the precision seeding have relatively consistent maturity, which are suitable for mechanized harvest. The rapeseed direct seeding is an important technical way to realize the sustainable development of rapeseed industry. In order to improve the seeding performance of the rapeseed pneumatic-typed precision centralized metering device, the main influence factors and their ranges were determined by analyzing the filling seed and clearing seed process. "Huayouza 62" was taken as experimental subject, while the cleaning angle was 53°, the protecting area angle was 90°, the throwing area angle was 110°, the protecting pressure difference was 150 Pa, and the section shape of air tap for clearing seed was circular and rectangular with the section area of 50.26 and 50 mm2, respectively. Three levels (8, 9, 10 m/s) were selected for the air velocity of clearing seed, 3 levels (19, 23, 27 mm) were selected for the filling height, and three levels (20, 30, 40 r/min) for the rotational speed of seeding cylinder. The speed of oil belt was 2.1-4.0 km/h. The L27313 orthogonal experiment was conducted to study the influence of cleaning seed and filling seed link on the performance of the centralized metering device on test bench. The influence factors were section shape of air tap for clearing seed, filling height, air velocity of cleaning seed and rotational speed of seeding cylinder, and the evaluation indices were coefficient of variation for seeding uniformity and variability coefficient of each row seeding quantity consistency. Results showed the order of the coefficient of variation for seeding uniformity was filling height > rotational speed of seeding cylinder > air velocity of cleaning seed > section shape of air tap for clearing seed; the order of the variability coefficient of each row seeding quantity consistency was filling height > section shape of air tap for clearing seed > rotational speed of seeding cylinder > air velocity of cleaning seed. Filling height, air velocity of cleaning seed and rotational speed of seeding cylinder obviously affected the seeding uniformity; section shape of air tap for clearing seed, filling height and rotational speed of seeding cylinder obviously affected the variability coefficient of each row seeding quantity consistency. Under the best working conditions that are section shape of air tap for clearing seed being rectangular, filling height of 27 mm; air velocity of cleaning seed of 10 m/s, rotational speed of seeding cylinder of 20 r/min, the coefficient of variation for seeding uniformity was 8.07%, and the variability coefficient of each row seeding quantity consistency was 1.95%, the damage rate was less than 0.1%. Thus improving the seeding performance of the rapeseed pneumatic-typed precision centralized metering device can be realized by expanding filling height, reducing rotational speed of seeding cylinder and auxiliary air for clearing seed. Also the hole, cone angle, seed-cleaning angle, relative situation between cleaning mouth and holes, and vibration are all main influence factors to the seeding performance. Based on the above results, further research is in urgent need for this rapeseed seeding metering device. The results provide the basis for the structure optimization of the pneumatic-typed precision centralized metering device and the improvement of its seeding performance.