多螺旋杆式丸粒化肉苁蓉精量排种器设计与试验

Design and Test of Pelleted Cistanche Seed Metering Device with Multi-helical Rod

摘要:

针对目前肉苁蓉诱导机制不完善而需要多轮补种以及传统肉苁蓉排种器散播面窄和散播面内均匀性差的问题，设计了一种多螺旋杆式丸粒化肉苁蓉精量排种器，采用螺旋杆机构使种子沿螺旋叶片前进并横向安装10根相同螺旋杆扩大了散播面，建立了丸粒化肉苁蓉种子与螺旋杆的动力学模型并通过理论分析和离散元仿真确定了螺旋杆的关键结构参数。基于肉苁蓉种植农艺和特定规格丸粒化肉苁蓉种子参数计算了理论排种量并运用离散元法分析了螺旋杆螺距、螺纹深度和螺旋杆转速等关键参数对排种性能的影响，应用EDEM软件构建丸粒化肉苁蓉种子和排种器离散元模型，以排种均匀变异系数和排种量变异系数为试验指标，通过单因素试验确定排种均匀性较优的螺旋杆螺距、螺纹深度和螺旋杆转速取值范围，仿真试验结果表明最佳螺距为15~20 mm，最佳螺纹深度为7~9 mm，最佳螺旋杆为60~100 r/min;进一步开展三因素三水平 BoxBehnken中心组合试验，利用Design-Expert软件建立多元回归模型并进行方差和响应面分析，以排种均匀变异系数和排种量变异系数最小为目标进行参数优化，求解得最优螺旋杆螺距为 17.77 mm、螺纹深度为 7.81 mm、螺旋杆转速为 83.32 r/min;依据优化后参数进行台架验证试验，结果表明在最优参数设置下排种均匀变异系数为 3.75%，排种量变异系数为5.33%。该设计满足丸粒化肉苁蓉诱导机制不完善下进行的散播作业农艺要求。

Abstract:

A multi-helical rod pelleted Cistanchis precision seed metering device was designed to address the problems of current imperfect induction mechanism of Cistanche which requires multiple rounds of replanting, as well as the problems of narrow dispersal surface and poor uniformity within the dispersal surface of Cistanchia seed metering device. A helical rod mechanism was used to move the seed along the helical and the dispersal surface which was expanded by installing ten helical rods.The kinetic model of pelleted Cistanche seeds and helical rod was established, and the key structural parameters of the helical rods were theoretically analyzed and determined. Based on the agronomy of Cistanchis cultivation and the parameters of pelletised Cistanchis seeds of specific specifications, the theoretical seeding rate was calculated. The effects of key parameters such as pitch, depth and rotational speed on seeding performance were analyzed by using the discrete element method. The model of pelleted Cistanchis seed metering device was constructed by EDEM. The variation coefficients of seeding uniformity and seeding capacity were used as the test indexes, and the ranges of pitch, depth and rotational speed were determined through a single factor test. The test results showed that the optimal parameter range of pitch was 15~20 mm, the optimal parameter range of thread depth was 7~9 mm, and the optimal range of rotational speed was 60~100 r/min. The BoxBehnken central combination test of three-factor and three-level was carried out, and a multiple regression model was established. The variance and response surface analyses were performed by Design-Expert software, the helical rod structure and working parameters were obtained through objective optimization. The optimal pitch of the helical rod was 17.77 mm, the depth was 7.81 mm，and the rotational speed was 83.32 r/min. The bench test showed that the variation coefficient of seeding uniformity and seeding capacity were 3.75% and 5.33%, respectively. The design met the agronomic requirements of seed dispersal under the imperfect induction mechanism of pelleted Cistanche, and provided a reference for research programme of seed metering device to improve the uniformity of seed dispersal in the dispersal surface of pelleted Cistanche.