Structural design and optimization of seed separated plate of wheat wide-boundary sowing device

Abstract: Wheat is one of the main grain crops in China. It has a great significance to ensure its sustained high and stable yield for maintenance food security in China. Studies have shown that the traditional wheat drill sowing technology is not suitable for the requirement of high and stable yield due to the bareness between rows, the insufficient utilization of land resources, the crowding between rows and plants, and the competing for water and fertilizer. Wide-boundary sowing was a new planting type of wheat, which can effectively improve the utilization rate of light, heat, water, fertilizer and land, it is meaningful to develop mechanized wide-boundary sowing technology. Wide-boundary sowing device is a core component of the technology. Structure and parameters optimization of wide-boundary sowing device were studyed based on the discrete element simulation technology, soil tank test and orthogonal test in this paper. The mathematical structure model of seed separated plate was established, spherical radius, installation angle and span were 3 key structural parameters of mathematical structure model. The discrete element simulation platform for wide-boundary sowing device, which mainly consists of particle factory, seed tube, cover plate for protect seed, side plate for support, seed separated plate and seedbed was set up. Taking the coefficient variation of wheat transverse uniformity as evaluation index, the influence of 3 key structural parameters on the performance of wide-boundary sowing device was analyzed, and the structure of seed separated plate was optimized according to the simulation results. The results of single factor simulation test showed that wide-boundary sowing device had relatively small coefficient variation of wheat lateral uniformity when spherical radius, installation angle and span at 130-150 mm, 30°-40° and 80°-100° respectively. According to the results of single factor experiment, the quadratic orthogonal rotation combination simulation experiments were conducted, and the regression equations of 3 key structural parameters and coefficient variation of wheat lateral uniformity were established. The orthogonal results showed that the main and secondary factors affecting coefficient variation of wheat lateral uniformity were installation angle, spherical radius, span, interaction between installation angle and span, and there was a certain interaction between installation angle and span. When spherical radius, installation angle and span were 141.26 mm, 35.53° and 90.72° respectively, coefficient variation of wheat lateral uniformity was minimum. in this case, the coefficient variation of wheat lateral uniformity of theoretical calculation value and simulation test value were 10.58% and 9.21%, respectively, and the deviation was only 1.37%, the regression model was accurate and credible. In order to validate the regression model established by simulation test and the optimization effect of structure parameters, a bench test of wide-boundary sowing device with the structure parameters optimization combination of seed separated plate was carried out. The results showed that the average coefficient variation of wheat lateral uniformity was 13.40%, and the deviation with simulation experiment results was 4.19%, which less than 5%, and considering there may be some errors in the bench test, so it was believed that the results of bench test was basically consistent with simulation test. This paper proved that the discrete element method was feasible to optimize the structural parameters of seed separated plate, the research results could provide references for optimizing the structural parameters of seed separated plate of wide-boundary sowing device and improving the performance of the wide-boundary sowing.