三七机械化挖掘收获工作机理与关键技术研究

Panax notoginseng is China's valuable Chinese herbal medicine,which has a high application and economic value. The Panax notoginseng’s planting area of Yunnan has increased year by year, the current market value is 50 billion yuan,and it’s expected to reach 100 billion yuan in 2020. The Panax Notoginseng’s planting mechanization degree is low,which has the following disadvantages, such as only by manual harvest, large amount of labor, high wages and low efficiency, thus seriously restricted development of Panax notoginseng industry . Based on the existing research, this paper builds on the existing research on the excavation mechanism, transportation mechanism, root and soil separation mechanism and obstructing the soil in the study process. Based on the study of the physical and mechanical properties of the roots and planting soils, the three - dimensional model of root - soil complex, excavation shovel, conveying mechanism and soil removal device was established, and the mechanism was revealed. The simulation results of excavation shovels are verified by soil tank test, and the design and operating parameters of excavation shovel are optimized, to study the relationship between excavation resistance and travel speed, land entry angle and soilcondition. The simulation results of the conveying mechanism are verified by thebench test, and the operating parameters such as conveying speed, amplitude and inclination of the lifting chain are optimized. The simulation results of the soil removal device are verified by the root soil separation test bed, and theoperating parameters are optimized. In order to achieve the target of drag reduction, flexible and non-destructive transport, efficient separation.

三七系我国名贵中药材，具有很高的应用与经济价值。云南三七种植面积逐年增加，目前市场价值为500亿元，预计2020年达到1000亿元左右。三七种植机械化程度低，人工收获，劳动量大、工时费高、效率低，严重制约三七产业发展。本项目在课题组现有研究基础上，针对研究过程中发现亟待解决的挖掘机理、输送机理、根土分离机理、壅土问题，在对三七块根与种植土壤物理机械特性研究基础上，建立根土复合物、挖掘铲、输送机构、去土装置的三维模型，并分别进行仿真分析，对上述机理进行揭示。通过土槽试验对挖掘铲仿真结果进行验证，优化挖掘铲设计与作业参数，研究挖掘阻力与行进速度、入土角、土壤状况的关系。通过台架试验对输送机构仿真结果进行验证，优化根土复合物输送机构，对输送速度、振幅、升运链倾角等作业参数进行优化。利用根土分离试验台对去土装置仿真结果进行验证，对作业参数进行优化。从而实现减阻降耗、柔性无损伤输送、高效分离的目的。

三七系我国云南道地名贵中药材，具有较高应用与经济价值，2022上半年中国三七出口数量为192.87吨，出口金额为384.79万美元。但三七收获机械化程度低，人工收获，劳动量大、效率低，严重制约三七产业发展。针对研究过程中发现亟待解决的挖掘机理、输送机理、根土分离机理问题，测定云南省多个地区三七块根平均密度、含水率；标定三七块根与65Mn之间静、动、碰撞恢复系数分别为0.199、1.07、0.177；土壤平均堆积角为31.37°。为后续研究以上机理提供数据支撑。挖掘机理揭示方面，设计仿生挖掘铲，开展静力学分析，得仿生挖掘铲总体形变量为1.7mm，满足强度设计要求。建立土壤-三七-挖掘铲EDEM离散元模型，剖析土壤与挖掘铲互作作用，根据仿真结果得出仿生挖掘铲可有效减少壅土。对比平面铲与仿生挖掘铲作业阻力，仿生铲阻力平均值为106.8N，减阻率为30.33%，减阻效果显著。输送分离机理揭示方面，明晰影响三七根土复合体输送与根土分离主要因素有升运倾角、速度、振动幅度、振动频率，以及升运倾角与振动幅度的交互作用对输送率的影响显著，次要因素为三七根茎尺寸、须根缠绕等，通过台架试验得到，当升运倾角为23°、振动幅度为26mm、升运速度为0.92m/s、振动频率为1.4Hz时，输送率平均值为93.6%，筛净率平均值为92.64%，输送分离效果良好。根土分离机理揭示方面，全矢量可视化表征三七根茎表面微观形貌特征，得出三七根茎表面平均粗糙度因子为4.14。构建三七根土复合体黏附力数学模型，得出土壤含水率为20.95%时，三七根茎与土壤之间的黏附力与三七根茎表面粗糙度因子、三七根茎表观表面积均成正比，实现了三七根土黏附力量化求解。开展仿真、田间根土分离试验，得出振动分离装置最佳作业参数为：振动频率10Hz，分离装置倾角5°，振动幅度6cm。此时，筛净率为90.1%，伤七率为2.22%，分离质量良好。该项目揭示了上述机理，指导应用攻关研究，改进机构设计，达到减阻挖掘、高效根土分离等目的，对三七以及根茎类作物收获机械的研制提供科学理论依据和方法，应用前景广阔。