Abstract: In order to reduce the soil opening resistance of soil opener and the soil return coefficient in the hole section of rapeseed pot seedling transplanter,according to the agronomic requirements of rapeseed pot seedling transplanting and characteristics of vertical soil opening, the shape optimization of soil opener was studied.The shape of soil opener for rapeseed pot seedling transplanter(square cone, cylindrical, square rhomboid), bottom size of soil opener, and soil opening depth were chosen as the experiment factors and discrete element method was used for simulation analysis of soil opening process. The longitudinal section size and top size of the hole formed by the soil opener were compared and analyzed, and the influence of various experiment factors on the quality of the soil opening operation was analyzed by taking the soil entry resistance and the soil return coefficient of the internal section of the soil opener as evaluation indexes.The simulation results showed that among the three kinds of soil opener shape, the optimal one was cylindrical, followed by square cone and square rhomboid. The upper size of the holes formed by the cylindrical soil opener was 72 mm, the effective depth was 43 mm, the soil entry resistance during the soil opening process was 62.8 N, and the soil return coefficient of the internal section of the holes formed was 0.07.Combined with the soil groove verification experiment and the soil entry resistance experiment of the soil opener on the universal testing machine, the operation performance of the soil opener was verified. The test results showed that the error values between the test results and the simulation results of the hole upper size, effective depth, and soil return coefficient of the internal section were 57%, 6.9%, 5.3% and 22.2%, respectively. The experimental results showed the optimized of soil opener shape and the combination of parameters were reasonable, and the holes that met the design requirements.

Key words: rape seedlings, transplants, soil opener, shape, discrete element method

摘要： 为了降低油菜钵苗移栽机成穴器的入土阻力及穴内回土量，根据油菜钵苗移栽的农艺要求，结合垂直入土成穴作业的特点，开展了成穴器外形优化研究。以油菜钵苗移栽机成穴器外形（方锥台形、圆柱台形、正菱台形）、下端尺寸、入土深度为试验因素，利用离散元法对成穴过程进行仿真分析，以成穴器的入土阻力与穴内截面回土系数为指标评价各试验因素对成穴作业质量的影响。仿真结果表明，较优的成穴器外形为圆柱台形，所成孔穴上端尺寸为72 mm，有效深度为43 mm，入土阻力为62.8 N，穴内截面回土系数为0.07。结合物理试验对成穴器作业性能进行验证，结果表明，孔穴上端尺寸、有效深度、入土阻力和穴内截面回土系数的试验结果与仿真结果之间的误差平均值分别为5.7%、6.9%、5.3%、22.2%。结果表明，优化后的成穴器外形及参数组合合理，所成孔穴满足设计要求。

关键词: 油菜钵苗, 移栽, 成穴器, 外形, 离散元法