基于土壤-甜菜互作特性的低损伤滚动挖挤收获机理研究

For lack of sugar beet harvesting theory and technology research in our country, there have the problems for digging mechanism, such as poor adaptation, bad soil breaking, easy blockage, and higher damage rate of sugar beet. In accordance with this situation, the mechanism of spoke disc beet digging device based on digging-crowding combination will be studied for improving the whole level of harvest technology. Based on the study for fracture relationship between the soil and sugar, physical characteristics of soil, the model of soil- beet will be established, which has a connection between beet flexible body model and the soil particles aggregate model. With the help of coupling numerical model in the harvest process, interaction mechanism among soil, beet, digging mechanism will be researched, the change law of stress distribution and movement for soil or sugar beet will be found out, and mechanism for effects of parameter of digging part on harvest performance will be ascertained. The coactions way of digging spoke disc, soil, the parameters distribution will be studied for figuring out the mechanism of beet damage with the aid of theoretical calculation, fluid-solid coupling simulation, experimental study and high speed photography. And the method and theory of rolling digging-crowding harvest in low damage based on soil - beet interaction characteristic will be obtained. A spoke disc beet digging device for sugar beet will be optimized and designed using digital and parameterized design method which can realize the reasonable distribution of soil flow field for digging sugar beet. And the result will provide theoretic support for high-performance harvester design and digging technology development.

摘要：针对我国甜菜收获理论及技术研究匮乏，现有挖掘收获机构存在适应性差、碎土效果差、挖掘易壅堵、对甜菜损伤率高等问题，基于土壤-甜菜互作特性，对辐盘式挖掘机构的滚动挖挤收获机理展开研究：分析甜菜及土壤的特性参数与甜菜断裂的关系，建立柔性体的甜菜模型、颗粒聚合体的土壤模型及两者之间的连接模型；借助收获过程的数值模型的耦合仿真分析，研究土壤、甜菜、挖掘机构之间的互作机制，揭示甜菜、土壤在挖掘过程中的受力及运动变化规律，探明挖掘机构对收获性能的影响机理及损伤率高的原因；采用数字化、参数优化等设计方法，研发低损、高效挖掘机构，形成滚动挖挤收获方法及理论。本研究将为高性能挖掘收获机构和适合我国甜菜种植特点的收获装备的研发奠定坚实的理论基础。

甜菜是我国重要的糖料作物，种植面积已达600万亩。目前，甜菜收获理论及技术研究匮乏，挖掘收获机构适应性差、碎土效果差、挖掘易壅堵、对甜菜损伤大，已成为制约甜菜机械化生产的技术“瓶颈”。. 辐盘式挖掘机构采用滚动挖掘的原理，挖掘阻力小，适应性强，可用于单株块根作物的挖掘收获。本项目基于土壤-甜菜互作特性，对辐盘式挖掘机构的滚动挖挤收获机理展开研究：分析甜菜及土壤的特性参数与甜菜断裂的关系，标定和构建了甜菜-土壤模型；搭建辐盘式挖掘台架，并通过力学分析校验关键部件性能；借助SoildWork构建辐盘式挖掘机构的三维虚拟模型，得到辐盘式挖掘机构的力学特征及工作动态，探索了土壤颗粒流场分布的控制因素。借助收获过程的数值模型的耦合仿真分析，研究了土壤-甜菜-挖掘机构之间的互作机制，探明挖掘机构对收获性能的影响机理及损伤率高的原因；采用数字化、参数优化等设计方法，明确了形成合理挖挤合力和土壤流场的机构条件，形成滚动挖挤的理论。以萝卜为例，验证了挖挤收获理论的适应性及可行性。. 挖掘辐盘可近似为两个三面楔。挖掘铲的倾角、偏角、张角主要影响挖掘铲的切土、碎土、翻土、推土的能力，决定着挖掘机构的挖掘效果及收获性能。依据土垡的破坏及运动形式，甜菜的收获过程可分为土壤切割区、挖挤区和抬升区。挖掘机构对土壤的滚动挖挤导致土壤破碎、断裂，影响着土壤给予甜菜的推力、挤压力和抬升力，容易导致甜菜折断；同时土壤的破碎和变形，影响着挖掘辐盘的随地滚动速度及土壤颗粒流的运动轨迹，易使得甜菜及土壤不能顺利通过挖掘机构，引起挖掘壅堵。考虑制造成本，挖掘机构参数：张角为15°，挖掘深度为80-120mm，偏转角i为25°-45°。辐盘挖掘装置可用于单株块根作物的收获，借助挖挤收获的工作机理，降低挖掘阻力及块根的损伤率。此外，探索了振动式挖掘方式的低频、高频振动减阻方式。. 项目共发表论文9篇，获批专利6项，培养研究生3人，科研助理6人。