并排双腔式排种器高速有序充种机理的研究

Years of practical application discovery that the problem of poor precision seeding caused by the cavity is appeared obviously in seeding process of mechanical precision seeding device.Under high speed operating conditions, the cavity is mainly caused by seeds bulk bagging as well as seeds do not having enough time to fill the hole because of the high linear velocity at the filling port.For the purpose of solving the problem of cavity, from the viewpoint of prevention of seed bagging and the effective guarantee of filling time for seeding,in this reseach new method of seeding orderly-queuing and zero speed-filling is proposed. This project makes intensive study on orderly queuing and zero speed seed-filling mechanism based on dual chamber in side by side seeding device with the V-groove structure. Kinematics and dynamic models of seed orderly queuing as well as zero-speed seed-filling were built to obtain the various factors and their relationship which effect the performance of orderly queuing and zero-speed seed-filling. To identify the main factors and appropriate parameters by simulating. Then, to improve the dual-chamber structure,as well as to determine the overall structure and parameters of seeding device based on orderly queuing and zero speed filling by testing.Thus to obtain primary and secondary factors which influenced the seeding performance and its optimal level combination by testing, as well as to establish the regression equation of each factors affecting the seeding performance. Also,multi-objective optimization design for the structure and operating parameters was carried on and the reliability and accuracy of optimization results were verified by experiment. All in all ,the reseach intent to producing a seeding device which has universal applicability and can be widely used in practice ,with dual-chamber structure in side by side,and solving the scientific problem of continuous and reliable seed-filling from the beginning in the seeding process under the high speed operating conditions when it works . The reseach output will provide technical reference for the study of the mechanical precision seeding device.

项目针对机械式精量排种器高速作业条件下种子堆积起拱和种子没有足够的时间充填型孔造成空穴而导致播种精度差的问题，从防止起拱和有效保障种子充种时间的角度出发，提出有序排队、零速充种新方法，研究基于V槽结构的并排双腔取种器高速作业条件下有序排队、零速充种机理，构建种子的运动学和动力学模型，明确影响种子有序排队、零速充种性能的各因素及其相互关系，仿真找出主要影响因素及其适宜参数范围，试验确定并排双腔取种器的结构方案和参数；搭建基于并排双腔取种器的排种器实验平台，试验确定影响其排种性能的主次因素及其最优水平组合，构建各性能指标影响因素的回归方程，并对影响各性能指标的结构与工作参数进行多目标设计优化，试验验证优化结果的可靠性与准确性，得到具有普遍意义且能广泛用于生产实践的并排双腔排种器产品，从源头上解决其高速作业情况下连续可靠充种的科学问题，并为机械式精量排种器的研究提供一定的参考。

高速精量播种技术是现代精准农业的发展方向与趋势，排种器是精密穴播播种机械的核心部件，其工作性能直接影响着播种精度、效率、种子的出苗率等。项目针对机械式精量排种器高速作业条件下种子堆积起拱和种子没有足够的时间充填型孔造成空穴而导致播种精度差的问题，从防止起拱和有效保障种子充种时间的角度出发，提出有序排队、零速充种新方法，设计一种双腔式精量排种器。项目构建种子的运动学和动力学模型，搭建排种器试验平台，通过高速摄像和台架试验分析确定影响有序排种性能的主次因素，构建各性能指标影响因素的回归方程。项目主要开展的研究内容与结论如下：首先以新疆广泛种植的三种型号的棉种为研究对象，对棉种的三维几何尺寸、千粒重、含水率、密度等物理参数，棉种的自然休止角、静摩擦系数、弹性模量等力学参数进行测试；对双腔式精量排种器以及关键部件的结构参数进行了设计，并对排种器的工作原理进行阐述；利用离散元软件EDEM对排种器的工作过程进行仿真分析，模拟种子运动状况，得到半精量取种腔的最优解为：半精量取种腔的进种口直径8.6mm，弧形槽长度为13.75mm，前腔携倾角为70.0°，此时根据目标函数预期得到的最优值是排种器的合格率93.4%，漏播率2.78%，重播率3.82%；利用高速摄像系统和JPS-12排种器试验台对双腔式精量排种器进行台架排种性能试验，在调序拨种轮安装角度为36°时，前进速度为6km/h时，种子脱离成穴器鸭嘴时，种子的空间位置存在一定差异，导致种子间位置距离减小或扩大，总体排种效果良好；通过仿真试验和理论分析确定影响双腔式排种器排种性能的主要因素为调序拨种轮安装角度、排种盘转速和充种腔的窝孔开口长度，采用三因素五水平的二次旋转正交组合设计方案进行试验，得出最佳参数组合：调序拨种轮安装角度为38°，排种盘转速为58r/min，充种腔的窝孔开口为13mm，性能指标达到最佳，合格率为94.6%，重播率为3.1%，漏播率为2.3%。项目解决其高速作业情况下连续可靠充种的科学问题，为机械式精量排种器的研究提供理论参考。