油菜扰动气力盘式穴播排种器参数优化与试验

    Parameter optimization and experiment of the disturbance pneumatic plate hole metering device for rapeseed

    • 摘要: 针对油菜气力式精量排种器作业速度提高易产生漏充影响穴播排种性能的问题,该研究对油菜扰动充种过程进行动力学分析,建立了扰动充种力学模型,明确了充种性能受到种盘转速、工作负压和种盘结构的影响;运用EDEM软件构建了可划分强制扰动区与摩擦扰动区的种子与种盘运动接触仿真模型,以槽齿厚度、槽齿数目和种盘转速为试验因素,以强制扰动区种群平均速度为试验指标,研究了各因素对种群扰动性能的影响规律,获得了较优的槽齿参数组合;以槽齿厚度、槽齿数目、种盘转速和工作负压为试验因素,以漏充率与充种合格率为评价指标进行了四因素三水平正交试验,通过极差分析得到了槽齿较优参数组合,即槽齿数为18、槽齿厚度为1.0 mm,与仿真结果一致,通过台架对比试验明确了对种群具有定向扰动的种盘可有效改善充种性能;开展了安装最佳种盘的穴播排种器穴播排种性能优化试验,以种盘转速与工作负压为试验因素,以空穴率与穴粒数合格率为试验指标,采用三水平析因试验设计,并对试验结果进行回归分析。结果表明,在种盘转速为40~80 r/min,工作负压在2392~2 500 Pa的条件下,空穴率均低于3%,穴粒数合格率均高于96%。田间试验表明,油菜种植密度为(70±4)株/m2,平均空穴率为4.6%,平均穴粒数合格率为90.54%,满足油菜农艺种植要求。该研究可为皖江地区油菜机械化穴播技术及装备研究提供参考。

       

      Abstract: Pneumatic precision metering device has widely been used for the planting of rapeseed in recent years. However, it is very necessary to improve the performance of hole-sowing and metering for a higher operation speed of the device in modern mechanized agriculture. In this study, a dynamic analysis was conducted on the disturbance filling process of rapeseed, then to establish a disturbance filling mechanical model. Particularly, an attempt was made on the parameter optimization and experiment of disturbance air-suction hole metering device for rapeseed. The result showed that the filling performance depended mainly on the rotation speed and structure of the seed plate, as well as the working negative pressure. The disturbance tooth presented a disturbing and pushing effect on the population, leading to the increase initial speed of seed migration. As such, the population close to the surface of seed plate was obtained the same initial speed as the suction hole, thereby increasing the contact time between the seed and suction hole, finally making the seeds close to the seed plate easily captured by the suction holes. A simulation model with the EDEM software was also constructed for the motion contact between the rapeseed and seed plate. The different structures of seed plate were used to determine the influence of structural parameters on the disturbance intensity of population, particularly the number and thickness of groove teeth. More importantly, the population in the filling room was divided into the forced and the friction disturbance zone. Correspondingly, a better parameters combination of grooved teeth was achieved to clarify the influence of various factors on population disturbance. Among them, the number and thickness of groove teeth, as well as the rotation speed of seed plate were selected to be the test factors, while, the average speed of population in the forced disturbance zone was used as the test index during parameter optimization. A performance test of bench filling was conducted to verify the simulation. A four-factor three-level orthogonal test was also carried out with the number and thickness of groove teeth, the rotation speed of seed plate, and the working negative pressure as the test factors, whereas, the missing rate and the filling qualification rate as the evaluation index. Additionally, a range analysis was utilized to determine the optimal parameter combination of groove tooth. Specifically, the optimal parameter combination was achieved, where the number of groove tooth was 18, and the thickness of groove tooth was 1.0 mm, indicating better consistency with the simulated ones. The optimized seed plate was selected for a better filling performance of disturbed and undisturbed seed plates under a low negative pressure via the performance test of bench filling. A bench comparison test also clarified that the seed plate with directional disturbance to the population effectively improved the seed filling performance. A three-level factorial design experiment was carried out with the seed plate rotation speed and working negative pressure as the test factors, and the cavity rate and the qualified rate of the seed in the hill as the test indicators, where the optimized seed plate was installed on the disturbance air-suction hole metering device for rapeseed. The regression analysis showed that the cavity rate was lower than 3%, and the qualified rate of seed in the hill was higher than 96% when the seed plate rotation speed was 40-80 r/min, and the working negative pressure was 2 392-2 500 Pa. The verification test with the same conditions was basically consistent with the predicted one. Field experiments demonstrated that the rapeseed planting density was (70±4) plants/m2, the average of empty broadcast rate was 4.6%, the average of pass rate was 90.54%, suitable for the agronomic requirements of rapeseed. This finding can provide a sound reference for the design of pneumatic drill hole planting and metering system.

       

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