Parameter optimization and experiment on cone canvas belt type seed-metering device

Abstract: The seed-metering link plays an important role in the process of plot sowing, and mechanized seed metering can reduce the labor intensity, improve the production efficiency and ensure the work quality. The seed-breeding seed-metering technology has been vigorously developed in China. However, at present, there are many disadvantages in the existing seed-breeding seed-metering device. In order to make plot sowing seed-metering device meet the requirements of high level test in plot sowing, this paper designed a cone canvas belt type metering device which applied a new type of structural material, analyzed the characteristics of the structure, and furthermore, optimized the parameters by means of composite test. This seed-metering device could avoid the serious defects that the cone grid plate type seed-metering device has, i.e. uneven seeding and seed injury. The mechanism consisted of a seed hopper, a seed-dispersing hand shank, a canvas belt type metering mechanism, a lever mechanism of adjusting tension, a base plate of seeding device, a receiving funnel and a spiral bevel gear. The structure parameters of the cone grid plate type metering device were not easy to distinguish and appraise. Some of them directly affected the performance of seed-metering device. Before further studying the parameter, the working process was divided into 3 links, which were discharging seeds, dispersing seeds and carrying seeds. By analyzing the seed mechanics, the seed kinematics and the conditions of space configuration about discharging seeds, dispersing seeds and carrying seeds, this paper found that a number of parameters had significant impact on the operation performance of the machine, and at the same time there was internal relationship between these parameters. Aiming at comparatively evaluating these parameters, this paper conducted the single factor experiment on discharging seeds. Through the above methods, the main parameters which influenced the performances of seed metering were identified: cone rotational speed, cone angle, and unit configuration amount in wedge-shaped ring domain. Through three-factor quadratic orthogonal rotation design, the regression equation of factors and test index (coefficient of variation of seed-metering uniformity) was established; the optimization of calculation showed that when the cone speed was 3.46 rad/s, the body bottom angle was 45.8°, and the unit configuration amount in wedge-shaped ring domain was 7 grains per centimeter, the comprehensive performance evaluation index reached the best level in the breeding test. Implementing the reproducibility test showed that the result of parameter optimization was accurate. The seed-metering technology was applied by 2BZH-6 type wheat nursery seeder for planting operation in different plot area. Under the condition of wheat seedling emergence, the statistical results were obtained by measuring the distance of the wheat plants: the average plant spacing was 51 cm for the cone grid plate type seed-metering device; and the coefficient of variation of uniformity distribution was 27.43%, which was relatively low. In addition, there was no phenomenon of residual seeds or broken seeds. The research results provide the reference for improving the design of the existing wheat nursery seeder's seed-metering component.