基于刚柔接触动力学的打结器设计方法与成结机构研究

Aiming at the difficult problem of knotter design and the knot-tied reliability problem of the knotter for quadrate bale type of baller, the project chooses anthropopathic dual-finger knotter presented by our team as research object, and will study on rigid-flexible interactive mechanical behaviours of tying a knot of the knotter by carrying on the analysis of rigid-flexible contact dynamics. The implementation method of tying a virtual knot of the knotter based on the theroy of rigid-flexible contact dynamics will be presented to reveal the motion process of tying a knot when the actuators of knotter act on two ropes. Whether the actuators can reliably tie a knot will be determined as the judgement rule, and the good or bad evaluation of the knotter during design phase wiil be finished. And then, the integrated development platform of mechanism analysis and design of the knotter will be built up. A rope-clasping mechanism, which can assist the knotter to twine a knot, will be presented. Based on the prototype of anthropopathic dual-finger knotter, the new knotter, which has a mechanism of forcibly tripping the knot and a mechanism of knot-hooking force control,will be designed to solve the problems which the existing knotter can't reliably trip a knot and ties a slipknot. The test validation of forming a knot and the reliability analysis of the knotter will be developed to evaluate the performace of the knotter. Simulation models and analysis procedures of the knotter will be improved and the design of the knotter will be directed. Research achievements of the project will provide the new mechanisms for high-speed reliable knot-tied of the knotter, and the new design method for disposable successful production of the knotter. At the same time, they will also have some reference values and universal significance to the analysis and design of rigid-flexible contact machine system.

针对方捆机打结器的设计难题和成结可靠性问题，本项目以课题组提出的仿人双指打结器为研究对象，通过刚柔接触动力学分析来研究打结器成结过程中捆绳被打结器执行机构作用的刚柔交互力学行为，提出基于刚柔接触动力学理论的打结器虚拟打结实现方法，以打结器执行机构能否可靠打出绳结为评判准则，完成设计阶段对打结器设计优劣的评价，并建立打结器机构分析与设计集成开发平台。提出辅助打结器绕扣的捆绳抱持机构，以仿人双指打结器为基本原型设计具有强制脱扣机构和钩结反力控制机构的新打结器，解决现有打结器不能可靠脱扣和打出活结的问题。开展打结器成结验证和打结器可靠性分析研究，进行打结性能评价和分析，改进仿真计算模型和分析过程，指导打结器设计。项目研究成果将为打结器高速可靠打结提供新机构，为打结器一次性制造成功提供设计新方法，对刚柔接触机械系统的分析与设计具有借鉴价值和普遍意义。

打结器是衡量方草捆打捆机成捆率的核心部件，直接影响打捆机作业性能和产品竞争力。国内企业长期依赖进口打结器制造打捆机，已成为制约我国打捆机技术发展的瓶颈，是困扰我国秸秆与饲草料行业30多年的行业难题。. 本项目针对打结器的设计难题和成结可靠性问题，提出了基于刚柔接触动力学的打结器设计新方法，突破了打结器设计技术壁垒。该方法通过建立大变形柔性捆绳与打结器刚性执行构件的多接触约束动力学模型，研究了捆绳拉力作用下打结器成结的刚柔交互力学行为，对打结器结构创新与样机制造前的打结直观验证起到重要作用，可在设计阶段评价打结器设计优劣，对降低打结器制造投入风险具有显著效果。. 通过对打结器夹绳-绕扣-钳咬动作参数分析、打结器脱扣机构的抗磨损设计与打结试验、打结器咬绳机构的线接触凸轮设计与载荷分析、打结嘴缠绳故障分析与曲面形态改进设计、打结器精密铸造零件的摩擦特性分析等应用基础研究，运用提出的打结器设计方法，基于D型打结器原理发明了一种双齿盘驱动打结器，创新设计特殊空间结构的打结器支架和空间传动机构，实现了打结器核心技术自主化。试验表明双齿盘驱动打结器的成结率≥99%，打结次数≥6万次，符合打结器行业标准要求。. 为了验证研发的双齿盘驱动打结器工作原理，并检验交变负载下打结器的疲劳寿命，弥补田间试验周期过长而且参数无法测量的缺点，提出了一种打结器连续打结试验方法与疲劳试验台设计方案，通过设计可模拟草捆回弹特性的拉绳装置使其在水平面按矩形轨迹拉绳，在绳针送绳动作配合下在垂直面形成矩形绳环，使受测试的打结器完成打结。该成果为打结器研发与质量控制提供试验平台，填补了国内空白，推动了打结器试验技术水平的发展。