Abstract:Different from traditional cultivation techniques of sowing in lines for wheat, precision seeding technology ensures the most reasonable distribution of wheat seeds in the field through precisely controlling seeding quantity and uniformity. Precision seeding technology can ensure the balance of nutrition in the growth process of wheat and achieve high quality and yield. The main component that affects the sowing precision of wheat seeder is seed metering device. The uniformity and stability of sowing are affected due to the pulsating of seed arrangement at low speed or small amount of sowing. However, in high speed operation, the diameter of the outer groove wheel seed metering device is small, when the speed is increased, the seed filling rate would be reduced, and the seed damage rate would be increased, it is difficult to achieve the goal of precision seeding of wheat. In order to realize the wheat single grain seeding technology, reasonable allocation of row spacing for wheat sowing, and improve the sowing quality of wheat seeder, a kind of differentspeed single grain seedmetering device with seedfilling groove for wheat was designed, and a 7.5cm row spacing narrow row wheat seeder was produced, the structure of “one seedmetering device with two seed rows” was realized, double row single grain sowing was realized, it provided technical support for close row spacing and uniform seed spacing. The design of the differential filling groove single grain seedmetering device with seedfilling groove for wheat was completed. EDEM discrete element software and Design-Expert 8.0.6 software were used to carry out simulation tests on the seed device and optimize the parameters of the differential filling groove single grain wheat seed device. A single factor experiment was completed by using EDEM discrete element software, it showed that the relative motion between the two sides alternate seedfilling and rotating seed wheel and stationary curved baffle was better for the seeding performance, the qualified rate was higher, which was 77.58%. The orthogonal experiment of the effect of the length, width and height of the seedfilling groove on the seeding performance was completed by using EDEM discrete element software, the simulation results showed that when the length between seed groove baffles was 8.00mm, the width of seed groove was 6.00mm, the height of seed groove was 5.00mm, the optimal results can be obtained. Based on these studies, the orthogonal combination test of multiple quadratic regression rotation was carried out on the basis of rotational speed, width of filling groove and raised slope angle of stationary curved baffle, then the DesignExpert 8.0.6 software was applied to analyze the test data, the relationship between the regression model and the influence of factors on indicators was obtained, the factors influencing the qualified rate of seeding were determined, the importance descending order was that rotational speed, width of filling groove and raised slope angle of stationary curved baffle, and the pair wise interaction cannot be ignored, the important factors influencing the variation coefficient of seeding uniformity, in order of importance, were the width of filling groove, rotational speed and raised slope angle of stationary curved baffle. Multiobjective parameter optimization was carried out based on regression model, the results showed that when the rotational speed was 1r/s, the width of filling groove was 6mm, and the raised slope angle of stationary curved baffle was 42.68°, it was predicted that the qualified rate of the seeding was 76.73%, and the variation coefficient of the seeding uniformity was 28.23%. The sample of seed metering device was made. Then some bench tests were carried out to verify the results, the results of bench tests showed that when the rotation speed was 1r/s, the qualified rate was 81.67%, the reseeding rate was 12.50%, the miss seeding rate was 5.83%, and the variation coefficient of the seed uniformity was 32.32%. The results were consistent with the simulation results. Field experiments were carried out on the wheat seeder trialproduced by using the differential filling groove single grain seedmetering device for wheat. The test results were consistent with the simulation test and the bench test results: the qualification rate of grain spacing was 82.50%, the replay rate was 9.17% and the missed replay rate was 8.33%, the mean value of the variation of sowing uniformity was 30.12%, which met and exceeded the national standards.
