Development of air-suction ridging and seeding machine for carrot

Combineding with the ridge planting mode of carrot in Shandong and other places, this research developed a air-suction precision carrot seeder which integrated the functions of ridging, ditching, precision sowing, covering soil and pressing was developed. The machine was mainly composed of air-suction precision metering device, ridging and shaping device, ditching and seed dividing device, soil covering device, frame and transmission system. According to the analysis of the force and movement of seeds in the process of seed suction and seeding, the critical value of vacuum degree in the air chamber of seed metering device was obtained, and the main influencing factors of seeding position and plant spacing uniformity were determined. A seed-metering plate with double-ring type hole was designed, the radius of the inner and outer circle holes of the seed-metering plate was 87.5 and 95.0 mm respectively, and the number of holes in each circle was 30. According to the requirements of seed cleaning and working space, the upper scraper removed the excess seeds adsorbed on the upper side of the inner and outer ring type holes, the zigzag structure was adopted. The lower scraper removed the excess seeds adsorbed on the lower side of the inner and outer ring type holes, and the eccentric structure was used. According to planting agronomic requirements, the FL-2.5 fan was determined to meet the requirements of different sowing air volume. Three double-wing ridging plows were used to ridge, and the ridge shape was trimmed by a shaping device to complete 2 trapezoidal ridges at one time. According to the requirements of double narrow row, shallow ditching and less covering soil, the structure of ditching and the parameters of overburden were determined. According to the analysis of the seed feeding process, the low-level seed feeding mode was adopted, and the seed metering the overall height of the ditching and seed separation device was about 100 mm. Taking the type hole diameter of the seed-metering plate, the rotating speed of seed-metering plate and the negative pressure of the air chamber as the test factors, and taking the eligible rae of seed spacing, the missing rate and the multiple rate as the test evaluation indexes, three-factor and five-level orthogonal experiment was carried out. The best working parameter combination for seed-metering device was abtained: the type hole diameter was 1.6 mm, the rotating speed of seed-metering plate was 18 r/min, and the negative pressure of the air chamber was 4.4 kPa. The field sowing experiments were carried out at working speeds of 3, 4 and 5 km/h respectively. The experiment results showed that with the increase of working speed, the eligible rate changed little, the multiple rate decreased, and the missing rate increased, but the overall scope of change was not large, the eligible rate was more than 94%, the missing rate was less than 5%, and the multiple rate was less than 4%, the working performance of the machine met the national standard and the requirements of carrot planting agronomy. The study can provide reference for the design of precision seeder for small seed vegetables such as carrot.