采棉机采摘系统摩擦学动力学耦合研究

The spindle is the key component of cotton picker, it's also expensive and easy to wear, which bring serious challenges to the economic benefits of cotton picker. In view of the need to solve the technical problem, based on the previous research, the project use the CASE 420 cotton picker spindle as the research object, through the friction dynamics experiment and friction surface morphological analysis,the friction model of spindle in picking process will be established, and established dynamics model of dry friction vibration system to describe the picking system of cotton picker, a semi-analytical method is used to study system response.Based on nonsmooth dynamics, numerical calculation theory, the nonlinear dynamic behavior(global, local) is revealed by change of spindle's related parameters, probed into establishment, transferation of chaos and its main influence factors, and fractal characterization of chaotic attractors is described,the primary factor effect on cotton picker spindle friction and wear will have been revealed.The research contents include: tribo-experimental study on spindle in picking process; established friction model of spindle in picking process; researched on friction dynamics of spindle in picking process.The results of the research will provide solutions for inhibiting or reducing spindle wear, and provide the foundation for prolonging the service life of the machine and the safety and reliability of use.

摘锭是采棉机采摘头的核心部件，也是成本昂贵的易磨损件，给采棉机使用的经济效益带来严重的挑战。针对这一亟待解决的技术问题，根据前期研究基础，项目以凯斯420采棉机摘锭为研究对象，通过摩擦动力学试验研究和摩擦表面形态分析建立摘锭在采摘过程中的摩擦力模型，进而建立描述采摘系统的干摩擦振动系统动力学模型，利用半解析方法研究系统响应。基于非光滑动力学、数值计算等理论进行非线性动力学研究,探讨摘锭相关参数变化时发生的非线性（全局、局部的）动力学行为，探索混沌的形成过程、转迁及其主要影响因素，刻画混沌吸引子的分形，揭示影响采棉机摘锭摩擦磨损的主要因素。具体研究内容包括：摘锭在采摘过程中摩擦学试验研究；建立摘锭在采摘过程中摩擦力数学模型；摘锭在采摘过程中的摩擦动力学研究。其研究成果将为抑制或减小摘锭正常摩擦磨损提供解决思路，进而为延长该类机械的使用寿命及使用安全可靠性奠定基础。

高端农机装备作为中国制造2025重点发展的十大领域之一，其核心在于提高农机装备关键零部件性能。采棉机的采摘工况复杂多变，使摘锭的受力状态及表面形貌发生复杂的演化，将会对其田间采净率和表面磨损失效起到决定性的影响。本项目以摘锭采摘过程的动力学与摩擦学耦合为出发点，研究其动力学行为、摩擦磨损规律及机理的基础上，提出摘锭表面改性处理方法，旨在提高其耐磨性。建立了摘锭采摘过程的力学模型，探讨了摘锭在间歇激励与摩擦力共同作用下的动力学行为。基于弹流润滑理论，采用COMSOL多物理场有限元仿真软件研究了摘锭涂层厚度、泊松比、弹性模量变化对摘锭结构性能的影响。借助三维白光表面形貌仪、扫描电子显微镜及能谱仪对摘锭表面磨损形貌进行测试分析。展现了采面机田间作业中摘锭表面形貌的磨损演化规律，揭示了摘锭表面涂层未脱落前磨损机理主要是表面擦伤和与棉纤维的机械磨损，涂层脱落后还存在氧化腐蚀磨损。搭建了纤维与硬质材料间的摩擦磨损实验装置，揭示了棉纤维在金属表面上滑动或自锁取决于摩擦系数和棉纤维直径与表面粗糙峰高度的比值。首次提出了摘锭的电磁强化处理并开展了田间试验，结果表明凯斯摘锭经电磁处理后与未经电磁处理的摘锭相比，耐磨寿命提高约20-30%。可有效减少摘锭更换次数并提升机采棉品质，具有显著经济效益和重要的社会意义。