Design and test of the precision seeding dispenser with the staggered convex teeth for wheat sowing with wide seedling belt

Wheat is one of the main food crops. Yield per unit area is one of the most important indexes in wheat production. The level of yield per unit area can greatly contribute to the national grain competitiveness. Among them, seeding quality directly dominated the wheat quality and yield level. The wide seedling and precision sowing can be expected to effectively improve the sowing quality of wheat. But the outer slot wheel seeding device cannot fully meet the wheat-wide belt seeding at present, due to the unstable displacement and low uniform seed distribution in the belt. In this study, a kind of precision wheat seeding device with staggered convex teeth was designed for the wide seedling belt, according to the outer slot wheel seeding device. The structure of the key parts was optimized to improve the seeding quality of the device. The continuous filling analysis was also carried out to derive the displacement formula. The key structural parameters were determined as the height and angle of the convex teeth influencing the consistent displacement and the uniform seeding. The simulation tests were then conducted to optimize the structure of the seeding device. First of all, the seeding tests were conducted to alleviate the influence of the staggered angle of the convex teeth. Different staggered angles of the convex teeth were arranged at different operating speeds. The test results showed that better consistent displacement and uniform seeding were achieved when the staggered angle of the convex teeth was 14°. Then, the center rotation combination simulation was carried out on these key structural parameters. The significant influencing factors on the consistent displacement cy and uniform seed distribution were ranked in the descending order of the convex tooth angle, the convex tooth height, and the operating speed, indicating all interactive effects. Response surface analysis showed that better displacement consistency and seeding uniformity were achieved when the convex tooth height was 5 mm and the convex tooth angle was 75°. The average coefficients of variation were 2.27% and 7.61%, respectively. The optimal combination of parameters was also tested in the bench test at the end of the simulation experiment. The bench test showed that the variation coefficients of simulated uniformity were less than 5%, indicating reliable and accurate optimization. A field comparison experiment was carried out between the precision seeding device of staggered spindle-belt wheat and the outer slot wheel seeding device, in order to further verify the simulation and bench test. The sowing capacity was set at 120, 150 and 180 kg/hm², respectively. The variation coefficients of sowing consistency, longitudinal sowing uniformity and transverse sowing uniformity were reduced by 0.99, 3.01, and 9.38 percentage points, respectively, compared with the outer slot wheel seeding device, which met the agronomic requirements of wheat sowing with the wide seedling belt. The key structural parameters were determined accurately on the discharge rate. The structure was also designed for the precision seed separator of zigzagging wide-seedling belt wheat. The cycle of structure optimization was reduced significantly by simulation. The finding can provide a strong reference for the design of wheat seeding device, in order to improve the seed uniformity.