Abstract

Aiming at the problem of lower single granularity and uniformity of the existing air-suction seed-metering device under the condition of densely planted crops according to the agronomic requirements of soybean-maize strip intercropping mode, the disturbing effect of seeds on the seed-filling performance was studied to improve the seeding performance of the seed-metering device under the condition of high speed. Based on the theory of discrete element method (DEM), taking the air-suction seed-metering device designed for both soybean and maize as a model and maize variety of ‘Zhengdan 958’ suitable for densely planted as the research object, the DEM single-factor test was conducted on the influence of the structure, position, and number of bosses on disturbing performance with the average kinetic energy, average velocity, and average normal force of seeds as evaluation indexes. The results showed that the disturbing performance of seeds was better when the boss structure was D-type, the diameter of the base circle where bosses located was 160 mm, and the number of bosses was 13. To further improve the structural parameters of the D-type boss, the primary structural parameters, such as the side length and arc radius, were simulated by a single-factor test. The position, side length, and arc radius of the D-type boss were further optimized and verified using central composite design (CCD) based on the results of the single-factor test. The CCD results showed that the average kinetic energy of seeds was 7.39 × 10⁻⁷ J, the average velocity was 4.53 × 10⁻² m/s, and the average normal force was 6.18 × 10⁻² N when the diameter of the base circle where bosses located at 159.865 mm, the side length and arc radius of the D-type boss of 5.690 mm and 5.476 mm, which significantly enhanced the disturbing performance of the seed-metering device. The optimized boss structures and parameters of the seed-metering device were validated with an all-factor test of working speed and working pressure. When the working speed and working pressure were 4 ~ 6 km/h and 7 ~ 7.5 kPa, the qualified rate was 94.75% ~ 97.49%, the multiple rate was 0.92% ~ 1.43%, and the leakage rate was 1.59% ~ 3.82%, all of which were substantially lower than the original one. Therefore, the seed-filling performance of the seed-metering device will be improved by increasing the disturbance of seeds to a certain extent.

中文翻译：

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基于DEM的气吸式密植排种器充种性能优化与试验

摘要

针对现有气吸式排种器在按大豆-玉米条带间作模式农艺要求密植作物条件下单粒粒度和均匀度较低的问题，对种子灌浆的干扰作用对排种器的性能进行了研究，以提高排种器在高速条件下的排种性能。基于离散元法（DEM）理论，以大豆和玉米气吸式排种器为模型，以密植玉米品种‘正单958’为研究对象，建立了DEM单以种子平均动能、平均速度、平均法向力为评价指标，对凸台结构、位置、数量对扰动性能的影响进行因子检验。结果表明，当凸台结构为D型、凸台所在基圆直径为160 mm、凸台数量为13个时，对种子的扰动性能较好。为进一步改进D型的结构参数，型凸台的边长、圆弧半径等主要结构参数通过单因素试验进行了模拟。在单因素试验结果的基础上，采用中心组合设计（CCD）对D型凸台的位置、边长和圆弧半径进行了进一步优化和验证。 CCD结果表明，当基体直径变化时，种子的平均动能为7.39×10 ^-7  J，平均速度为4.53×10 ^-2  m/s，平均法向力为6.18×10 ^-2 N。 D型凸台的圆直径为159.865毫米，D型凸台的边长和圆弧半径分别为5.690毫米和5.476毫米，显着增强了排种器的扰动性能。通过工作速度和工作压力全因素试验验证了排种器优化后的凸台结构和参数。当工作速度和工作压力为4～6 km/h、7～7.5 kPa时，合格率为94.75%～97.49%，倍数率为0.92%～1.43%，泄漏率为1.59%～3.82% ，所有这些都大大低于原来的水平。因此，通过在一定程度上增加对种子的扰动，可以提高排种器的充种性能。