精量播种机V型凹槽拨轮式导种部件设计与试验

为提高导种投送均匀性与稳定性,满足精量播种作业要求,设计了一种Ⅴ型凹槽拨轮式导种部件,对其滑移导种曲线、Ⅴ型凹槽和柔性拨种轮进行优化分析。依据离散元法建立导种部件-玉米籽粒间作用模型,运用EDEM软件对导种投送环节进行虚拟仿真,分析籽粒在导种管内滑移状态。以勺式玉米排种器为排种载体,结合正交试验设计和虚拟仿真技术进行多因素正交旋转试验,以机具前进速度、排种器工作转速和导种曲线投种点切线倾角为试验因素,合格指数与变异系数为试验指标,采用多目标变量优化方法建立因素与指标间的数学模型,运用Design-Expert 6.0.10软件进行数据处理优化。仿真表明,当前进速度、工作转速和切线倾角分别为7.69 km/h、29.47 r/min和46.10°时,导种均匀性及稳定性最优,其合格指数为92.05%,变异系数为8.00%。在此基础上,利用室内台架开展了高速摄像测定试验、性能对比试验及振动适应试验。试验结果表明,多数籽粒在导种管内以平稳状态滑移,极少数出现不规则碰撞及翻滚;所设计的导种部件对不同类型玉米籽粒适应性良好,且其合格指数与无导种管基本相同,变异系数优于可伸缩塑料导种管、弧形导种管及无导种管,可适用于勺式、指夹式和气吸式玉米排种器;在振动幅度为1~3 mm、振动频率为1~4 Hz工况下,振动幅度及频率对导种部件作业均匀性影响较小。

Design and Experiment on V-groove Dialing Round Type Guiding-seed Device

A V-groove dialing round type guiding-seed device was designed to improve the uniformity and stability of planting and meet the requirements of precision planting. The overall structure and working principle of the precision guiding-seed device were illustrated and analyzed. The optimal design of structural parameters of key components was conducted, such as guiding curve, V-groove and dialing round. The interaction model of machinery and maize was established by using discrete element method. The scoop-type metering device was taken as the seeding object and EDEM software was employed to simulate the guiding-seed process. And then the dynamic behaviors of maize were researched under the working conditions. Orthogonal simulation experiments were carried out based on numerical simulation technology with forward speed, rotational speed, tangent angle as experimental factors and with qualified index and coefficient of variation as assessment consumption. Based on experimental data, a mathematical model was built, and the experimental factors were optimized by Design-Expert 6.0.10 software, the best combination was achieved. The simulation results showed that as the forward speed was 7.69km/h, rotational speed was 29.47r/min, tangent angle was 46.10°, and the qualified index was 92.05%, the coefficient of variation was 8.00%, which could meet the requirements of precision planting. On this basis, the high-speed photography experiment, comparison performance experiment and vibration adaptation experiment were carried out. The experimental results showed that the majority of grains were slipping in a steady state in the tube and few irregular impacts and tumbling. The V-groove dialing round type guiding-seed device had better adaptability to different maize grains which could be used in conjunction with scoop-type, pickup finger-type and air suction-type precision seed metering device. Its qualified index was similar to that of unguided tube, and coefficient of variation was higher than those of retractable plastic guide tube, curved guide tube and unguided tube. Under the normal operating conditions (vibration amplitude was 1~3mm, and vibration frequency was 1~4Hz), the vibration amplitude and frequency had little effect on the homogeneity of the guided parts.