气吸圆盘式微型薯排种器充种性能模拟与试验

Simulation and Experiment on Seed-filling Performance of Pneumatic Disc Seed-metering Device for Mini-tuber

为提高气吸圆盘式微型薯排种器充种性能,以云南丽薯6号微型薯为播种对象,基于离散元法,以种子平均法向应力方差为指标,对振动频率和振动幅度分别进行数值模拟,并对上述因素进行单因素试验,试验结果与仿真效果一致。结果表明:增加振动频率和振动幅度可以增大种子平均法向力方差,增强对种子的扰动性,从而提高充种性能。为寻求最佳工作参数组合,采用三因素五水平二次旋转正交组合试验方法,对排种器进行排种性能试验,并对试验结果进行优化与验证。结果表明:在作业速度为2.4 km/h,吸种负压为6 kPa,种层高度为70 mm,振动频率为6.5~6.9 Hz,振动幅度为20~21 mm时,合格指数大于95,重播指数和漏播指数小于2.5。

In order to realize the mechanized planting of mini-tuber and solve the problem of large seed filling,a vibrating feeding pneumatic disc seed-metering device for mini-tuber was designed. The seedmetering device was composed of metering plate,air chamber,frame and vibrating seed feeding device.Seeding-filling performance was the key factor that influenced the properties of metering device. In order to improve the seed-filling performance of the pneumatic disc seed-metering device,Lishu No. 6 minituber was adopted as sowing object,the method of UDEC was used as research technique,meanwhile,variance yields of average normal stress was considered as the optimizing targets. Through single factor experiment,the vibration frequency and vibration amplitude were numerically simulated respectively. It can be found that the experimental phenomenon and effect were in consistent with the simulation ones.Results showed that vibration frequency and vibration amplitude increased variance yields of average normal stress of seeds,hence disturbance of seeds was enhanced. Based on the three-factor five-level quadratic orthogonal rotating combination test method,the influence of vibration frequency,vibration amplitude and layer height on sowing performance were explored. The regression equations of the three factors and five levels were fitted through the processing by Design-Expert 8. 0. 6（ experimental design expert） software. Based on the results of examination,it can be found that the fitting of the equation was good,and the best parameter combination was the operating speed of 2. 4 km/h,negative pressure of6 kPa,vibration frequency of 6. 5 ～ 6. 9 Hz,vibration amplitude of 20 ～ 21 mm and layer height of70 mm. Under the optimal condition,the qualified index was greater than 95,and the multiple index as well as the missing index was less than 2. 5. It showed that the vibrating feeding pneumatic disc seedmetering device met the standard and requirements by comparing the results with the national standard.The research approach was suitable for the exploitation of mini-tuber seed-metering,and it provided a theoretical reference for the design of pneumatic disc seed-metering device.