菠菜分体铲式入土仿形切割装置设计与试验

Design and Test of Split-body Shovel into Soil Copying Cutting Device for Spinach

摘要:

针对现有叶类蔬菜土下切割部件采用的一体式带刀无法适应菠菜宽幅垄面横向起伏，导致切根失败的问题，本文设计一种分体铲式入土仿形切割装置，旨在降低垄面条件对菠菜切根效果的影响。通过运动分析确定铲刀运动方式，结合离散元仿真，得到铲刀主要结构参数。根据铲刀运动要求，设计曲柄连杆-平行四杆组合式传动机构。通过机构-土壤互作受力分析，确定仿形机构整体结构与压缩弹簧结构参数。利用复数矢量法构建传动机构数学模型，根据铲刀切割轨迹优化分析，确定切割部件随地表上下浮动过程，前进速度与曲柄角速度间的速比系数与仿形杆件纵坐标函数关系，并通过田间试验验证切割轨迹优化结果的准确性。基于最优切割轨迹得到分体铲式入土仿形装置最佳作业参数组合：曲柄角速度18.85 rad/s、速比系数7.92 mm/rad，此时平均切根合格率为95.23%。最优作业参数组合下，开展了仿形机构作业性能验证试验，结果显示留根长度保持在11 mm±3 mm范围内，平均留根变异系数为37.96%。对比现有一体式带刀采收装备与分体铲式切割装置作业效果，结果显示分体铲式切割装置留根变异系数平均降低约63.42个百分点，切根合格率平均提高约17.4个百分点。研究结果为菠菜收获机研究提供了新的切割方式，为整机研发提供了部件支撑。

Abstract:

Aiming to address the problem that existing integrated blade-type underground cutting devices for leafy vegetables cannot adapt to the lateral undulations of wide ridges in spinach cultivation, leading to root cutting failures, a split-body shovel into soil copying cutting device was designed to reduce the impact of ridge conditions on spinach root cutting effectiveness. The shovel's motion mode was determined through motion analysis, and the main structural parameters of the shovel were obtained by using discrete element simulation. Based on the shovel's motion requirements, a crank-connecting rod-parallel four-bar linkage transmission mechanism was designed. Through mechanism-soil interaction force analysis, the overall structural parameters of the contour-following mechanism and the compression spring were determined. A mathematical model of the transmission mechanism was constructed by using the complex vector method. Based on the shovel cutting trajectory optimization analysis, the speed ratio coefficient between the forward velocity and crank angular velocity during the up-and-down movement of the cutting component with the ground surface was determined, along with the functional relationship between the longitudinal coordinates of the contour-following rods. Field trials verified the accuracy of the optimized cutting trajectory results. Based on the optimal cutting trajectory, the best operating parameter combination for the split-shovel type soil-entry contour-following device was obtained: crank angular velocity was 18.85 rad/s, speed ratio coefficient was 7.92 mm/rad, at which the average root cutting qualification rate was 95.23%. Under the optimal combination of operating parameters, a performance verification test of the contour-following mechanism was conducted. The results showed that the root length was maintained within the range of 11 mm±3 mm, with an average root length variation coefficient of 37.96%. Comparing the operating effects of existing integrated blade harvesting equipment and split-shovel cutting devices, the results showed that the split-shovel cutting device reduced the root length variation coefficient by an average of approximately 63.42 percentage points and increased the root cutting qualification rate by an average of approximately 17.4 percentage points. The research results can provide a novel cutting method for spinach harvester research and offer component support for the overall machine development.