蔬菜育苗高压静电吸附播种机理及系统参数优化

    Mechanism of high-voltage electrostatic adsorption seeding for vegetable seedlings and optimization of system parameters

    • 摘要: 针对现有气吸式穴盘育苗播种机对含杂较多且没有丸粒化的不规则小颗粒蔬菜种子存在吸孔堵塞而导致排种精度下降的技术难题,该研究摒弃小孔径、长导程吸孔,设计了一种基于高压静电吸附特性的蔬菜育苗播种机。通过理论分析及电势等值线分布仿真试验确定介电绝缘层材料;构建静电吸附力学模型,明确影响静电吸附力的主要因素及其相互关系,确定影响播种性能的电参数及范围;以型孔加工直径、正向高压静电发生器输出电压和种箱底面倾斜角度为试验因素,以播种合格指数、重播指数和漏播指数为响应指标进行三因素三水平Box-Behnken中心组合试验,得到各试验因素与响应指标间的数学模型,应用 Design-Expert 10.0.4 软件对数学模型进行多目标优化,得到最佳参数组合为:型孔加工直径5.91 mm、正向高压静电发生器输出电压17.67 kV、种箱底面倾斜角度14.69°,此时播种合格指数为91.13%、重播指数为3.02%、漏播指数为5.85%。播种性能验证试验的播种合格指数相较于优化结果降低了0.61个百分点、重播指数相较于优化结果降低了0.17个百分点、漏播指数相较于优化结果增加了0.78个百分点。试验误差在允许范围内,参数优化结果可靠,满足精量播种技术要求。研究结果可为不规则小颗粒蔬菜种子精量播种机械装备的研发提供参考,同时也可为不规则小颗粒物料定量吸附和快速分离方法研究及设备开发提供参考。

       

      Abstract: Aiming at the existing air suction hole tray seedling sowing machine in the face of more impurities and no pill granulation irregular small particle vegetable seeds there are suction holes clogging and lead to the decline in the accuracy of seed discharge technical problems. In this study, a vegetable seedling planter based on high-voltage electrostatic adsorption characteristics was designed by discarding the small aperture and long conductance suction holes. The dielectric insulating layer material is determined by theoretical analysis and simulation tests of potential contour distribution. The results show that: as the relative dielectric constant of the dielectric insulating layer gradually increases, the distribution of equipotential lines between the type hole and the seed box is gradually dense, the potential difference gradually increases, the electric field is gradually strengthened, and the electrostatic adsorption force on the polarised seeds gradually increases, and the adsorption state becomes more and more stable; Construct a mechanical model of electrostatic adsorption, clarify the main factors affecting the electrostatic adsorption force and their interrelationships. The results show that the main factors affecting the size of the effective electrostatic adsorption force in the pore are the output voltage of the electrostatic generator, the hole machining diameter, the material of the dielectric insulating layer, the relative permittivity of the seed layer, the spacing between the pore and the seed layer, and the material of the electrode sheath and the inner and outer diameters of the pore. And determine the electrical parameters and ranges affecting the seeding performance; A three-factor, three-level Box-Behnken centre combination test was carried out with the hole machining diameter, positive high-voltage electrostatic generator output voltage and tilt angle of the seed box bottom as test factors, and sowing pass index, reseeding index and leakage index as response indicators. The results showed that the order of influence of the test factors on the sowing compliance index was the output voltage of the forward high-voltage electrostatic generator, the hole machining diameter, and the tilt angle of the bottom of the seed box; and the order of influence on the reseeding index and the leakage index was the hole machining diameter, the output voltage of the forward high-voltage electrostatic generator, and the tilt angle of the bottom of the seed box. The interaction terms of the diameter of the pore processing and positive HVEG output voltage had significant effects on seeding pass index, reseeding index and leakage index. Mathematical models were obtained between the test factors and the response indicators. Applying Design-Expert 10.0.4 software to optimise the mathematical regression model with multiple objectives, the best parameter combinations were obtained as follows: the hole machining diameter 5.91 mm, positive high-voltage electrostatic generator output voltage 17.67 kV, and tilt angle of the bottom of the seed box 14.69°, and the sowing qualification index at this time was 91.13%, the reseeding index was 3.02%, and the omission index was 5.85%; In the seeding performance verification test, the seeding pass index decreased by 0.61 percentage points, the reseeding index decreased by 0.17 percentage points and the missed seeding index increased by 0.78 percentage points compared to the optimised results. The test error is within the permissible range, and the parameter optimization results are reliable and meet the technical requirements of precision sowing. The results of the study can provide a reference for the research and development of mechanical equipment for precision sowing of vegetable seeds with irregular small particles, and at the same time, provide an academic reference for the research of quantitative adsorption and rapid separation methods and equipment development of irregular small particles materials.

       

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