Design and experiment of stratified seed-filling room on rice pneumatic metering device

Abstract: The technology of rice's mechanical direct seeding can significantly reduce the consumption of manpower and material resources, and meanwhile maintain the production of rice. Super hybrid rice is a kind of hybrid rice and its tillering ability is stronger than the general hybrid rice. Due to the characteristics of high tillering capacity of super hybrid rice, the sowing quantity is required to be 1-3 seeds for each hole when super hybrid rice seeds are directly seeded to the field by the drilling machine, so as to ensure the high precision of seeding and high rate of field seedling emergence. In order to meet the requirement of 1-3 seeds for each hole using the precise hill-drop drilling technique, a seed-filling stratified room was designed, which was between the seed-metering device and the seed box on pneumatic feed mechanism for precision rice hill-drop sowing. It also aimed at improving the liquidity of seeds and raising the seeding precision, the liquidity of rice seed would reduced after accelerating germination. This the reduction of the liquidity of rice seed after accelerating germination had so bad effects on filling process that it limited the improvement of metering performance. Indic hybrid Peizataifeng was taken as the research object, and the impacts of the seed-filling stratified room on the performance of the pneumatic feed mechanism was studied by the single-factor experiment and orthogonal experiment in this paper. These experiments were carried out under different negative pressures for sucking seeds and positive pressures for blowing seeds. The experimental results showed that there existed an optimization condition on the capability of the metering device to meet the needs of the production. The probability about the quantity for each hill was used to evaluate the capability of the pneumatic precise metering device. The seed-filling stratified room consisted of a barrel and two seed-guiding plates. The cross-section of the barrel was the square with 50 mm per side. There were the chutes on the lining of the barrel, which were 1.1 mm wide. Seed-guiding plates were 1 mm thick, which were connected with the barrel by chutes. The two seed-guiding plates formed an angle of 45 degrees. The optimization condition was that the sucking plate's rotation speed was 30 r/min, the negative pressure for sucking seeds was 1.6 kPa and the positive pressure for blowing seeds was 0.1 kPa. With the seed-filling stratified room, the probability of 1-3 seeds per hill for the metering device was 95.4%; in addition, the probability of empty seed was 1.53%, and the probability of greater than or equal to 4 seeds was 3.07%. Under the same condition, the probability of one seed per hill for the metering device was 17.32%; in addition, the two-seed probability was 58.72% and three-seed probability was 19.36%. Compared with the existed researches, the results showed that the seed-filling stratified room between the seed-metering device and the seed box on pneumatic feed device, had a good influence on the precision of the pneumatic seed-metering device, improved the fluidity of the seeds and decreased the friction force and extrusion force among the seeds. This study provides an important reference for the structure optimization and the performance improvement of the pneumatic metering device.