棉秆拔秆收获机理分析及机构优化

During the lifecycle of cotton production, activity-based cost of cotton-stalk harvesting is second only to cotton harvesting. Uprooting is the most popular way among farmer, since it could harvest the whole cotton-stalk therefore avoids the adverse effects of residual stubble on the next planting. At present, the dynamical behaviors of uprooting harvest and formation mechanism of its operation qualities are still un-clear, the problems of low uprooting net rate and low efficiency has not been resolved, accordingly, gathering and utilization of cotton-stalk is restricted..Taking the typical breed of cotton as study objects in this project, biological and mechanical parameters of cotton-stalk, and physical characteristics of the soil will be measured, existing uprooting components will be synthesized and analyzed, and the model of cotton-stalk uprooting will be established, simulation and field experiment will be taken to reveal the mechanism of cotton-stalk uprooting influenced by structural and operational parameters of the components, thereby, the uprooting components will be optimized, to achieve the best combination of structural and operational parameters. The project includes four research topics: .(1) Basic data related to the dynamics simulation model;.(2) Multibody dynamics of soil–cotton-stalk–uprooting components;.(3) Mechanism of cotton-stalk uprooting qualities；.(4) Optimization of cotton-stalk uprooting components..This project will provide theoretical support for the design of cotton-stalk pulling harvest machinery, and will promote the utilization of cotton-stalk resources.

棉秆收获是棉花生产中作业成本仅次于棉花收获的环节。拔秆收获能实现棉秆的全部收集，可避免残留根茬对下一轮作物的不利影响，是最受农民欢迎的收获方式。目前棉秆拔秆收获动力学特性和作业质量产生机理不明晰，存在拔净率过低和作业效率低下等问题，制约了棉秆资源的收集和利用。.本项目以华北棉区典型棉花品种为研究对象，测定棉秆生物与力学特性参数、土壤物理特性参数，对现有拔秆机构进行总结分析，构建棉秆拔秆收获作业模型，开展仿真分析与田间试验，揭示拔秆机构结构参数和工作参数对于拔秆收获作业质量的影响机理，对拔杆机构进行优化，实现结构和工作参数最佳组合。研究内容包括：(1)动力学仿真模型的相关基础数据研究；(2)土壤-棉秆-拔秆机构的多体动力学研究；(3)棉秆拔秆收获作业质量影响机理研究；(4)棉秆拔秆机构优化研究。本研究可为棉秆拔秆收获机械的研发提供理论依据，有助于促进棉秆资源的综合利用。

棉秆收获技术落后，制约了棉秆资源的收集利用。为探明棉秆拔秆收获动力学特性和作业质量产生机理，解决拔净率低和作业效率低等问题，主要开展了以下三个方面的研究工作：（1）棉秆植株力学特性与拔秆阻力测定：研究了棉秆含水率和直径对其抗弯、抗拉特性和拔除阻力的影响规律。结果表明，棉秆抗弯强度与含水率呈负相关，抗拉强度与含水率呈正相关，平均拉伸破坏载荷是平均弯曲破坏载荷的29.8-10.9倍。棉秆的拉拔阻力呈先增大后减小的趋势，仅受拉力不能使棉秆发生破坏。（2）棉秆拔秆多体动力学分析：棉秆顺利拔出包含夹持、起拔、输送和退秆4个阶段，棉秆被拔起时不仅要求拉拔力不小于土壤阻力，最大拉拔力还需持续作用一定时间，齿盘对棉秆所作有效功应不小于棉秆被拔起所需的最小能量。速比大小决定拔秆周期长短，速比大则拔秆周期短，速比小则拔秆周期长；起拔时间过短易造成漏拔或拔断，齿盘转速过高易导致棉秆断裂。棉秆呈斜向上运动为最优起拔姿势，齿盘倾斜起拔效果优于水平起拔效果。（3）棉秆拔除机构设计与优化：采用电液控制技术，设计并制造了齿盘式多行棉秆拔除试验台架，开展了大田试验。试验结果表明：速比对各考核指标的影响主次顺序为：拔净率、拔断率、漏拔率；前进速度对各考核指标的影响主次顺序为：漏拔率、拔断率、拔净率；最佳组合为：拖拉机前进速度0.85m/s、速比0.75，此时棉秆具有最高的拔净率，为93.89%，拔断率和漏拔率最低，分别为4.43%和1.68%。.项目执行期内，发表论文4篇，其中EI收录1篇、中文核心期刊收录3篇，获发明专利授权3项、实用新型专利授权5项，获软件著作权1项。.以棉花秸秆为研究对象，探明了棉秆个体的拔除动力学规律，提出了拔秆机构优化设计思路和工作参数组合，可有效指导现有棉花秸秆拔除环节的操作，具备较强的应用价值。研究结果仅适用于单行种植模式，具有局限性；另外，棉秆-土壤-拔秆机构多体动力学研究难度大，需要开展进一步研究。