机械免耕播种切拨防堵装置的工作机理与参数优化研究

As a result of power driven residue cutting and clearing device on no-till planter was used in northeast area of China, Shape of previous ridge was broke, germination and sprout rate was slowed, advantage of ridge cropping system rising temperature was declined. The study was based on mode of conservation tillage under high residue conditions（including whole stalk, broken stalk, and high crop rootstalk）and analyzed the organic connection of system "soil－crop－machine", put forward new technical standard－geometry model of seed bed that was made by no-till planter. Three-dimensional direction resistance test device of corn residue was developed to check the best cutting direction and cutting speed, determined the best cutting scheme by orthogonal experiment. Dynamic analysis and virtual testing were studied to determine the best parameter by using computer to make residue cutting and clearing device model. Then, the practical device and research platform were developed to validate whether the academic analysis was accurate and the effect of no-till planting was perfect. Profile modeling structure of row unit was newly developed to adjust to high-speed process. In the theory of System Dynamics guidance, dynamic model of no-till planter with residue cutting and clearing device at vertical minim shake was formed to implement system dynamic simulation, optimize parameter and experimental study in order to ensure seeding quality of no-till planter and minimum drawing resistance. The successful implementation of the subject established scientific system info of residue cutting and clearing device applied no-till planter and research platform, provided the design theory and experiment foundation.

东北地区应用免耕播种机驱动式破茬装置，破坏原垄形成新沟，出苗缓慢，失去垄作升温优势。本项目以垄作三种覆盖模式（高留茬整秆、高留茬碎秆、高留茬覆盖）为对象，分析"土壤-作物-机器"系统有机联系，提出工艺标准，构建免耕播种种床土壤耕作的几何模型。研制玉米根茬三维方向阻力测试装置,正交试验，探求最佳切割方向、切割速度等，确定最佳破茬方案；进行拨切防堵装置实体建模、动态分析与虚拟试验，确定最佳参数组合，并研制室内试验台，验证理论与免耕播种效果。适应地形变化与高速作业，研发新型单体仿形机构，加装弹簧与阻尼器复合体；在系统动力学理论指导下，建立免耕播种机纵向铅垂面微振动的动态模型，进行系统动态模拟、参数优化和试验研究，保证免耕播种作业质量并且达到最小牵引阻力。本项目成功实施，将系统地建立免耕播种拨切防堵装置的科学理论体系与研究平台，为具有自主知识产权的玉米垄作免耕播种机的研发，提供设计理论与试验基础。

按项目计划主要研究内容与取得成果如下：.⑴对土壤理化特性测试研究，构建垄作耕法垄形断面图和种床几何模型及相关尺寸。提出免耕播种种床环境条件：5～10㎝耕层温度10～12℃,土壤含水量13%以上,土壤上松下实。.⑵研制阿基米德螺线型缺口圆盘破茬刀，对其结构参数优化：圆盘刀缺口数11齿，最大半径215㎜，起始半径175㎜，包角32.72º。建立破茬刀破茬阻力与机器前进速度vm、切割夹角θ、圆盘角速度ω二次回归数学模型及优化参数（vm为11㎞/h、θ为0º、ω为13rad/s）。.⑶研制破茬开沟装置和切拨防堵装置。破茬开沟装置开V形沟宽度28㎜（选螺线型缺口圆盘刀2片其直径350㎜、入土深度40㎜）；切拨防堵装置破茬深度70～100㎜，开沟宽度40～50㎜，清垄宽度210㎜。确定切拨防堵装置最优参数（机器前进速度2.22m/s，单体重量113㎏，破茬深度7.50㎝）。.⑷在破茬刀刃口曲线上加工锯齿，增大摩擦力使钳住根茬能力增大，切割质量好。通过运动学分析，建立数学方程；优化设计破茬犁刀运动平面与机组前进方向偏角6º，开沟宽度4㎝，不仅劈开根茬，而且为播种开沟器提供松软种床利于种子扎根出苗。通过试验最优性能参数：机组前进速度5㎞/h，单体配重113㎏，切茬深度84.5㎜，牵引阻力0.96kN功耗小，切茬质量高。.⑸研制3台试验装置：①玉米根茬三维方向阻力测试装置，用于测试圆盘破茬刀的性能参数，确定切割方向、速度，阻力和功耗等。②圆盘破茬刀切割玉米根茬运动特性测绘装置，测绘出阿基米德螺线型缺口圆盘破茬刀待测点运动轨迹是由不同长度圆弧组成云曲线，建立运动学模型。揭示破茬刀运动轨迹既有光面圆盘破茬刀摆线规律，又有半圆型缺口圆盘破茬刀冲击性，滑切角较大，破茬率高。③免耕播种机土壤工作部件测试装置，可测试土壤工作部件性能参数。当机器前进速度5㎞/h、破茬深度7.52㎝时，工作阻力1868.38N，受力方向角度67.66º，其着力点作用线与被测工作部件中心距离4.59㎝，配重190㎏。.⑹研制仿形加载机构和2BQM-2型免耕播种机。通过开沟深度和弹簧形变量时域分析，建立传递函数。机器速度5㎞/h，弹簧形变量均值0.26cm，变异系数38.5%。免耕播种机系统为欠阻尼衰减振动系统，阻尼比0.62，与原仿形机构对比分析，系统响应时间减少18%，最大超调量减小32%，系统平稳。