杂交稻气力滚筒集排式排种器楔形搅种装置设计与试验

Design and experiment of wedge churning device for pneumatic cylinder-type seed metering device for hybrid rice

为提高杂交稻气力滚筒集排式精量排种器的排种精度,该文设计了一种楔形搅种装置,以解决滚筒型排种器由于充种时间短和吸种区稻种架空造成吸种精度低的问题。以厚度1、2和1~2 mm(带有坡度,其最薄处厚度为1 mm、最大厚度处为2 mm)3种楔形搅种装置为研究对象,简化排种器模型,进行了搅种过程离散元仿真模拟,以吸孔附近稻种层的平均法向接触力和平均三轴合速度为评价指标,分析了不同搅种装置对种群内摩擦力变化的影响,得出1~2 mm带有坡度的搅种装置对稻种种群的搅动效果较好;以杂交稻种晶两优1212为研究对象,采用三因素五水平二次回归正交旋转组合试验,研究在1~2 mm带有坡度的楔形搅种装置下吸种负压、滚筒转速、清种距离(清种指到吸孔边缘距离)对滚筒型排种器排种性能的影响。结果表明:以漏吸率(X1)、合格率(X2)、重吸率(X3)为评价指标,预测最优组合为吸种负压为1.60 kPa、滚筒转速为10 r/min、清种距离为1.94 mm,其合格率为84.67%,重吸率为7.92%,漏吸率为7.41%,试验验证上述最优组合:合格率为86.00%,重吸率为8.47%,漏吸率为5.53%。该研究结果表明,安装1~2 mm带有坡度楔形搅种装置对稻种的分离、搅动和助吸有明显作用,可提高排种器吸种性能,为进一步优化杂交稻气力滚筒集排式精量直播机排种性能提供依据。

To meet the requirement of the precise direct-seeding for hybrid rice,the study aimed to design the wedge type churning device,which on the basic of pneumatic cylinder-type seed metering device.As the shape of rice seed is slender,long and sharp,with edges,villus,and poor fluidity,the wedge-shaped churning device was designed to improve suction accuracy.The previous experimental results show that the installation of an electromagnetic vibration device at the bottom of the seed box can help the cylinder metering device to suck seeds,but it is not suitable for field use.A directional churning device and a linear churning device for a vertical disc rice pneumatic metering device was designed,the experimental results show that the directional churning device can improve the seed suction precision of the metering device according the previous research of the author’s team.According to the triaxial size of typical hybrid rice varieties,three kinds of churning devices with thickness of 1 mm,2 mm and arc-shaped churning device with slope thickness from 1mm to 2 mm were designed,which was made of ABS plastic and fixed on the outer surface of the cylinder,with two suction holes on both sides of the churning device.The straight-line distance between the two ends of churning device is 10mm,and five groups in the cylinder axial direction,eight groups in the cylinder circumference In order to test the churning performance,the virtual simulation was investigated by means of discrete element method,the model of the seed metering device was drawing out by 3D cad design software.According to the average triaxial size,the rice seed model made by multi-spherical particles with radius from 0.2 mm to 1 mm were packed and filled in EDEM software.The mass,volume and moment of inertia were calculated automatically by EDEM model.The average normal contact force and triaxial resultant velocity towards to the cylinder of the rice seed near suction holes were compared.The average normal contact forces produced by seed agitator on rice population were respectively-1.37×10^-5,-1.42×10^-5 and 7.54×10^-6 N.The results showed that the churning effect of arc-shaped churning device with slope thickness from 1mm to 2 mm was better than the others.Taking the Jingliangyou 1212 rice seeds as the experiment material,using three factors and five level orthogonal rotatory experiment for arc-shaped churning device,the influence of negative pressure of the suction chamber,rotation velocity of cylinder,and cleaning distance(distance between the cleaning device and the hole edge)on the suction performance were studied.The results showed that the prediction optimal parameters of the regression model were as follows:the negative pressure was 1.60 kPa,rotation velocity of cylinder was 10 r·min-1,the cleaning distance was 1.94 mm,with the qualified rate of 84.67%,the over sucked rate of 7.92% and rate of seed empty of 7.41%.The test results showed that the qualified rate was 86.00%,the over sucked rate was 8.47%,and the rate of seed empty was 5.53% under condition with optimal parameters.The results showed that the arc-shaped churning device with slope thickness from 1 mm to 2 mm for cylinder-type seed metering device had a significant effect on the separation,agitation and suction for the hybrid rice,which could improve the seed suction performance,and provide a reference for the further optimization.