铲筛式农田石块捡拾收集机仿真与试验

针对农田表层土壤中含有较多石块容易造成水土肥流失，影响作物生长以及降低触土农业机械使用寿命的问题，设计一种铲筛式农田石块捡拾收集机，捡拾并收集土壤表层0~350 mm深度范围内的石块，应用离散元法和田间试验对机具工作参数进行优化。采用EDEM软件对输送分离筛与石土混合物的相互作用过程进行数值模拟，设计Box-Behnken仿真试验研究输送分离筛的3个工作参数(线速度、振幅和振频)对石土筛分、输送过程的影响，并以收集箱内石土混合物的含土率为评价指标，对输送分离筛的工作参数进行优化；以仿真优化的工作参数进行田间试验，验证机具的作业性能，并将仿真优化结果与田间试验结果进行比较。结果表明:1)振幅、线速度和振频对含土率影响显著，含土率随线速度增大而增大，随振幅和振频增大而减小，线速度与振幅对含土率具有显著的交互影响作用，三者对含土率的影响依次减弱；最优参数组合为，线速度1.6 m/s、振幅35.5 mm、振频10.67 Hz，该条件下仿真试验的含土率为7.17%；2)最优参数组合下田间试验的含土率为10.73%，与同条件下仿真试验结果差异较小，说明仿真优化的工作参数准确、可靠；田间试验的石块漏捡率为4.86%，符合相关标准的规定。

Simulation and experiment of shovel-screen type farmland stone picking and collecting machine

The surface soil of farmland contains more stones can easily cause water, soil and fertilizer losses, which affects crop growth and reduce the service life of soil-touching agricultural machinery. Aiming at the problem, this study designed a shovel-screen type farmland stone picking and collecting machine to pick and collect stones in the depth range of 0 to 350 mm soil surface layer, and applied the discrete element method and field test to optimize the working parameters of the machine. The numerical simulation of the interaction process between the conveying-separating screen and the stone-soil mixture was carried out by EDEM software. The Box-Behnken simulation experiment was designed to study the effects of three working parameters(linear speed, amplitude and vibrating frequency)of the conveying-separating screen on the screening and conveying process of stone-soil mixture and optimize the working parameters of the conveying-separating screen with the soil content ratio of the stone-soil mixture in the collecting box as the evaluation index. Field test was conducted with the simulation-optimized working parameters to verify the operational performance of the implements, and the optimized result of the simulation was compared with that of the field test. The results showed that amplitude, linear speed, and vibrating frequency all had significant effects on soil content ratio; Soil content ratio increased with increasing linear speed and decreased with increasing amplitude and vibrating frequency; Linear speed and amplitude had significant interactive effects on soil content; The effects of the three on soil content ratio weakened in turn; The optimal parameter combination was a linear speed of 1. 6 m/s, an amplitude of 35. 5 mm, and an vibrating frequency of 10. 67 Hz, and the soil content ratio of the simulation experiment under these conditions was 7. 17%. The soil content ratio of the field test under the optimal parameter combination was 10. 73%, which was less different from the simulation result under the same conditions, indicating that the working parameters optimized by simulation were accurate and reliable. The stone leakage rate in the field test was 4. 86%, which was in accordance with the relevant standards.