油菜联合收获割台落粒损失产生机理与控制策略

Rape is an important economic crop. In recent years, the level of rape mechanization has made great progress, but there is still a big gap compared with rice and wheat mechanization. Especially, there is a great potential to improve the performance of mechanized harvesting. This application is aimed at seed losses on the cutting platform. Specific studies are as follows:①Based on the theory of elastic-plastic finite element and dynamic substructure technique, the dynamic model of elastic-plastic collision between the cutting platform divider, reel, cutter, conveying auger and rape plant can be established separately. Moreover, combining with the simulation analysis method and high-speed photography observation technique, the cracking and crack propagation mechanism of rape pods under external impact effect during the suitable harvest period will be revealed; ②Vibration response of cutting platform under rape combine harvester working condition will be obtained by means of vibration test. Based on spectrum analysis method, the vibration frequency of multisource vibration excitation acting on the cutting platform can be measured. Researching on coupling resonance effect by comparing the vibration frequency of the cutting platform with rape plant natural frequency, the cracking and crack propagation mechanism of rape pods under external multisource vibration effect during the suitable harvest period will be revealed; ③On this basis, control strategy to reduce the cutting platform seed loss can be proposed. By means of improving the structure and optimizing the operating parameters of the cutting platform, power reduction, seed loss decrease and harvest efficiency improvement will be achieved.

油菜是一种重要的经济作物，近年来我国油菜机械化生产水平取得了长足进步，但与稻麦相比仍有较大差距，尤其是机械化收获环节的作业性能还有很大提升空间。本申请针对割台损失这一衡量油菜联合收获作业性能的关键指标之一，研究油菜联合收获过程中割台落粒损失产生机理与有效控制策略。具体研究：①运用弹塑性有限元理论和动态子结构技术，分别建立割台分禾器、立式割刀、拨禾轮、输送搅龙与油菜植株弹塑性碰撞动力学模型，结合高速摄影和仿真分析，揭示适收期油菜角果在外界碰撞作用下开裂及裂纹扩展机理；②动态测试田间收获工况割台的振动响应，基于频谱分析，研究割台多源激励的振动频率，耦合对比分析适收期油菜植株的固有频率，研究二者共振效应，揭示适收期油菜角果在外界多源振动激励作用下开裂及裂纹扩展机理；③提出降低割台落粒损失的控制策略，优化割台结构参数和运行参数。达到降低割台功耗、减少落粒损失和提高收获效率的目的，为解决油菜生产季节性矛盾，提高油菜产量和机械化生产水平奠定理论基础。

为研究割台落粒损失产生机理，提出有效减损控制策略，本项目主要完成了以下研究工作：①试验研究了适收期“华油杂62”油菜植株生物力学特性，主要包括角果抗裂角力、茎秆剪切力、适收期油菜植株固有频率和不同部位的振动特性等。②基于梳脱式油菜联合收获机割台研究了从拨禾轮开始接触油菜到油菜茎秆被切断全过程中割台与植株之间的相互作用过程，通过二者相对运动过程中的相对几何位置关系分析，建立了茎秆相对拨指辊运动线速度、梳刷次数等与割台结构参数之间的数学模型，理论上分析了割台的梳脱性能；开展了台架试验，研究了梳脱机构对割台梳脱性能和割台落粒损失的影响规律，并优化了梳脱式割台关键部件的结构参数和运行参数。③在田间工况下测试了油菜联合收获机割台激励频率，明确了割台主要振源；与适收期油菜植株固有频率（5~10 Hz）进行耦合对比分析，明确了割刀是引起割台振动落粒损失的最主要影响因素。④基于田间试验探究了梳脱式油菜联合收获割台梳脱降损方案的可行性，同时设计了割台高度自适应调节系统，实现了割台随路面起伏自动调节高度，达到通过控制喂入量以降损的目的。