稻茬田谐振刮离自脱附旋耕防粘机理研究及应用

The rice stubble field of the middle and lower reaches of the Yangtze River has the characteristics of heavy clay soil, high water content, high stubble and large quantity of straw, therefore, plenty of clay soil adhere to the tiller during the rotary tillage operation. So that, it is urgent to study the anti-sticking mechanism and structure of rotary tillage aiming for rice stubble field. In this project, mechanical scraping anti-sticking technology and mechanical vibration desorption technology are brought into rotary tillage. Theoretical analysis, simulation and experimental tests are conducted to figure out the characteristic of paddy soil-rice straw complex and the mechanical property of sticking. Constitutive model and contact model of the complex are established and the sticking laws of rotary tiller are clarified. The interaction between scraping device and the adherent complex on rotary tiller is explored from both microscopic dynamics and macroscopic anti-sticking effects, meanwhile mechanism of anti-sticking scraping device is revealed. The vibration response characteristics of the complex under the harmonic excitation vibration are studied and, the mathematical model of the vibration-desorption quality of the complex is constructed. The vibration-desorption mechanism of the complex is revealed and, threshold excitation amplitude and excitation frequency of the complex self-desorb from scraping device are defined. An anti-sticking device for rotary tiller with harmonic scraping self-desorption is proposed, the test bench is trial-produced, and the structural parameters are optimized and, the device is applied to the rotary tiller in rice stubble field. The successful implementation of this project will provide a reference for anti-sticking of rotary tillage equipment in the paddy field in the middle and lower reaches of the Yangtze River.

长江中下游农业区稻茬田具有土壤粘重、含水率大、留茬高、秸秆量大的特点，旋耕机具作业时粘附土壤稻茬严重，迫切需要针对稻茬田特性，研究旋耕防粘机理与机构。本项目提出将机械刮削防粘技术与机械振动脱附技术引入旋耕防粘中，拟采用理论分析、模拟仿真、试验测定等方法，开展稻茬田土壤-稻茬复合体特征、物理力学与粘附特性研究，构建复合体本构模型与接触模型；探明旋耕机具粘附规律；从微观动力学和宏观防粘效果层面，阐明刮离机构与旋耕机具粘附的复合体之间相互作用关系，揭示稻茬田刮离旋耕防粘机理；研究简谐激励振动下复合体振动响应特性，构建复合体振动脱附质量数学模型，揭示复合体振动脱附机理，明确刮离机构粘附复合体自脱附临界激励振幅和激励频率；提出谐振刮离自脱附旋耕防粘机构方案，试制试验台，优化机构结构参数，应用于稻茬田旋耕机具中。本项目的研究为解决长江中下游农业区稻茬田旋耕机具粘附问题提供参考。

旋耕是长江中下游水旱轮作区重要耕整方式，由于稻茬田具有常年干湿交替、土壤粘重的特点，旋耕刀辊作业时粘附土壤严重，迫切需要基于稻茬田的土壤特性研究旋耕减粘脱附技术与配套脱附装置。本研究针对长江中下游水旱轮作区稻茬田旋耕刀辊减粘脱附的实际工程需求，提出将机械刮削防粘技术与机械振动脱附技术引入旋耕防粘中。采用理论分析、模拟仿真、测定试验等方法，以长江中下游水旱轮作区耕层土壤作为试验材料，探究土壤物质组成表征量对耕层土壤结持特性影响和不同耕作方式下土壤流变性随含水率变化规律，开展稻茬田环境下土壤本构模型与接触模型研究，进而基于离散元法解析稻田湿黏土壤与旋耕部件粘附过程；基于旋耕刀辊切抛土过程的运动学及动力学分析，明确脱附装置与旋耕刀辊粘附土壤之间的相互作用关系；搭建振动脱附试验台，研究振幅、振动频率和振动时间等振动特性参数对切向、法向上的界面粘附系统土壤脱附效果影响，阐明简谐激励振动下土壤的振动响应特性，获得粘附土壤脱附临界激励振幅和激励频率；结合上述研制了一种振动横挡阻隔式旋耕防粘刀辊，在最优参数组合下进行田间试验，结果表明：旋耕防粘刀辊土壤粘附量远小于常用旋耕刀辊，耕深稳定性系数、厢面平整度、碎土率、粘附量、轴向分布均匀度和秸秆埋覆率均值分别为92.02%、15.21mm、81.81%、2.63kg、10.99%和92.27%，均满足国家标准与农艺要求。本项目所形成旋耕减粘脱附技术与配套脱附装置应用于稻茬田旋耕机具中，可达到长江中下游流域旋耕机高效作业的目的。研究结果不仅可为稻茬田高性能旋耕机的设计奠定坚实的理论和技术基础，而且是改善耕地质量、促进农业绿色发展的重要举措，对农业可持续发展具有重要意义。