风筛选式油菜联合收割机清选机构参数优化与试验

为分析油菜田间实际收获作业状态时风筛选式油菜联合收割机清选机构参数对清选损失率和籽粒含杂率的影响,基于双滚筒风筛选式可移动田间联合收获试验平台,对振动筛振幅、曲柄转速、风机转速和风机倾角4个参数进行了Plackett-Burman试验和响应面回归试验,试验分析表明振动筛振幅和曲柄转速是影响清选损失率的主要因素,风机转速是影响籽粒含杂率的主要因素。采用响应面试验方法分析了单因素和双因素对清选效果的影响,建立了清选损失率和籽粒含杂率的回归数学模型并优化求解了一组最优参数组合,以一组接近最优参数组合:振动筛振幅35 mm,曲柄转速392 r/min,风机转速1 750 r/min,风机倾角29°进行了试验验证,清选损失率和籽粒含杂率分别为0.90%和0.45%。理论求解的清选损失率和籽粒含杂率分别为0.38%和0.48%,与试验值的绝对误差分别为0.52%和-0.03%,籽粒含杂率误差较小,清选损失率误差较大。与该清选机构常用工作参数时的清选损失率和籽粒含杂率对比,清选损失率降低了61%,籽粒含杂率降低了58%。该研究结果和优化方法可为风筛选式油菜联合收割机清选机构的参数选择和优化提供参考。

Parameter optimization and experiment on air-screen cleaning device of rapeseed combine harvester

Abstract: China is one of the major rapeseed production countries in the world, but the harvesting mechanization is still backward, and high mechanical harvest loss is a key inhibiting factor for rapeseed production. In order to reduce the harvest loss ratio, the effects of the parameters of air-screen cleaning device of rapeseed combine harvester on cleaning loss ratio and percentage of impurities in grain under the actual field harvest operating condition are needed to understand. In this paper, a Plackett-Burman test and a response surface test were designed to study the 4 parameters: vibration screen amplitude, crank revolving speed, fan revolving speed, and fan dip angle based on a two-roller and air-screen field mobile harvest testbed. The Plackett-Burman experiment results showed that the vibration screen amplitude and the crank revolving speed had significant influences on the cleaning loss ratio, and the effect of the amplitude was greater than that of the crank revolving speed, but the fan revolving speed and the fan dip angle had not significant impact; the results also showed that the fan revolving speed had significant influences on the percentage of impurities, while the other 3 parameters had not significant impact. The response surface regression variance analysis showed that the effects of the 4 parameters were not the linear relation but the interaction; the predicted values of quartic polynomial regression model were consistent with the measured values in the experiment, and the regression models of the cleaning loss ratio and the percentage of impurities were solved and the values of R2 were 0.9559 and 0.9660 respectively. The single factor and two-factor analysis results indicated that the vibration screen amplitude had a little impact on cleaning loss ratio near zero level, reducing the crank revolving speed could remarkably lower the cleaning loss ratio, and increasing the fan revolving speed could remarkably lower the percentage of impurities. A group of optimal parameter combinations under the constraint condition could be acquired by solving these regression equations, and a checking test was carried out by using an approximately optimal parameter combination: vibration screen amplitude of 35 mm, crank revolving speed of 392 r/min, fan revolving speed of 1 750 r/min, and fan dip angle of 29°. The cleaning loss ratio and the percentage of impurities were 0.90% and 0.45% respectively in the test, but when these parameters were applied into the regression mathematical models, the cleaning loss ratio was 0.38% and the percentage of impurities was 0.48%, and the absolute errors were 0.52% and -0.03% respectively. Compared with the field result that was based on the common parameters, the cleaning loss ratio dropped by 61% and the percentage of impurities dropped by 58%. The analysis results indicated that the relationship between the parameters of cleaning device and the cleaning loss ratio and grain percentage of impurities was correct and the precision of regression mathematical model could meet the need for optimizing the parameters of air-screen cleaning device. The results can provide theoretical basis and technical references for the parameter selection and optimization of air-screen cleaning device of rapeseed combine harvester.