多约束条件下香蕉仿形落梳机理

Banana is the top most tradable fresh fruit in the world. China is the world's second top banana producer. Crown cutting is one of the most important parts of banana postharvest treatments. So far, it is operated manually all over the world with low production efficiency and high labor intensity, besides, banana can be easily damaged during manual operation. Mechanization of banana crown cutting is a bottleneck in the development of entire mechanization of banana postharvest treatments. This project targets the mechanization of banana crown cutting and aims to confirm the multi-constraints of shape size, cutting force and cutting track in the process of banana crown cutting by analyzing the shape characteristics of banana stalk and crown and biological structure constitution of banana crown. The axial distribution rule of cutting force vector will be researched based on multi-constraints’ coupling effect in order to establish the matrix equation of separating banana hand from the stalk. In this project, cut surface quality, work efficiency and energy consumption will also be carried out as indexes in researching cutting tools’ parameters like structure, size and position and cutting parameters like track, velocity and angle to achieve high-quality banana crown profile cutting. This project will provide a basis for realizing the mechanization of banana postharvest treatments. It is also the reference for the mechanization of pruning and defoliation of some plant stalks or branches, as well as fruit picking.

香蕉是全球鲜销量最大的水果，中国香蕉产量位居世界第二。落梳是香蕉采收处理的重要环节，目前都是人工作业，生产效率低、劳动强度大、果实损伤严重，机械化落梳是香蕉采收处理机械化的发展瓶颈。项目以机械化落梳为目标，分析香蕉梳柄几何尺寸特征、生物结构特征和果轴几何尺寸特征，研究梳柄的力学特性，明确香蕉落梳过程中的几何尺寸、力和轨迹约束条件。基于多约束耦合效应，获得插切力矢量沿果轴轴向的分布规律，构建果梳分离矩阵方程；以切口质量、作业效率和能耗为指标，研究刀具结构、尺寸及位置等落梳刀具参数和插切轨迹、速度及角度等插切参数，并进行优化，以实现高质量香蕉仿形落梳。项目研究既为香蕉采收处理机械化的实现提供依据，也为茎杆类植物机械化去枝、去叶、去果等提供参考。

本项目对香蕉梳柄和果轴的形态特征与仿形落梳装置的设计机理进行了系统深入地研究，有效填补了香蕉采后处理环节中机械化落梳领域的空白，为类似采收处理机械的研究设计提供了借鉴和理论依据。. 为揭示机械化落梳过程中，香蕉梳柄与刀具、果轴与仿形机构间的相互作用机理，对香蕉梳柄和果轴的宏微观和生物力学特征进行了研究；并以此为基础，分析了刀具插切梳柄过程中切割力演变规律，设计了不同的仿形落梳刀具，开发出可自适应果轴的仿形落梳装置。. 通过测量梳柄和果轴的物理、形状、尺寸和组织分布等特征，获得了梳柄和果轴的形态生物学参数，建立了落梳刀具的几何约束及仿形机构的轨迹约束。通过开展梳柄和果轴的力学性能试验，确定了香蕉落梳过程中的力约束。.依据梳柄的几何和力约束，通过ANSYS软件对刀具插切过程进行了动力学仿真分析。结果表明在切割载荷作用下，香蕉梳柄的剪切强度随着切割力的增大呈现先增大后降低的变化趋势，且在剪切强度达到极限后迅速降低。另外，设计了多种仿形落梳刀具并优化了刀具的组合参数。. 按照香蕉落梳的农艺需求，并结合果轴的轨迹约束，以提高落梳刀具对果轴的径向自适应和转动自适应性能为目的，设计了轴向冲击插切式落梳和周向旋转式振动落梳机构，开发了可周向包络果轴的轴向冲击插切式落梳装置、基于恒力机构的轴向冲击插切式落梳装置、可展式轴向冲击落梳装置和周向旋转落梳装置。通过理论分析、试验和应用测试对机构的可行性进行验证，结果表明，项目中所提出的可展机构可以实现设计目的，并达到了预期的工作效果。