复式耕整机耕深与耕宽稳定性分析与试验

Analysis and experiment of tillage depth and width stability for plowing and rotary tillage combined machine

针对设计的复式耕整机出现的耕作稳定性问题,结合复式耕整机整体结构及工作原理,从牵引、水平面内受力、机器振动3个角度分析影响耕作稳定性因素,确定影响耕作稳定性关键因素为牵引角、犁体配置斜角、旋耕刀升角。以牵引角、犁体配置斜角、旋耕刀升角为试验因素,以工况耕深稳定系数和工况耕宽稳定系数为性能评价指标进行二次正交旋转组合试验。正交试验结果表明:试验因素对评价指标影响程度从高到低皆为:犁体配置斜角、牵引角、旋耕升角,当各影响因素分别取值为17.3°、27.8°、72.6°时,工况耕深稳定系数和工况耕宽稳定系数分别为91.8%、93.4%。以影响因素最优参数组合为基础进行的验证试验结果表明:试验后工况耕深稳定系数和工况耕宽稳定系数为91.5%、93.1%,与软件分析结果基本一致,且其他耕作指标均达到农艺要求。该研究可为复式整地机械的耕作稳定性研究提供技术参考。

The plowing and rotary tillage combined machine developed in this study is a duplex-operation scarification machine designed with the combination of plough mechanism and rotary tillage mechanism in the front. Such a design allows the cultivator to accomplish multiple tasks simultaneously, such as plow tillage, rotary tillage, straw chopping for mulching, soil pulverization, soil covering, and surface leveling. To investigate the stability of the plowing and rotary tillage combined machine, the factors such as cultivator tillage stability were examined from 3 different aspects： traction, force analysis in the horizontal plane, and vibration analysis. The center of mass of the machine could be determined on the longitudinal vertical plane of the machine, where the traction line passing through the instantaneous center of rotation intersected with the vertical line passing through the center of mass. The traction angle（15°-30°）, i.e., the angle between traction line and horizontal line, was a crucial factor affecting tillage stability. The forces acting on the machine on the horizontal plane during operation were analyzed to obtain the plow tilt angle（23°-30°） from the equilibrium equations of the plough, rotary blade, and traction forces on the horizontal plane; the plow tilt angle affected tillage stability by directly impacting the force balance on the horizontal plane. From an analysis of the vibrational excitation during machine operation, it was determined that alternating load in rotary blade operations was the main source of machine vibration excitation. The lift angle of the rotary blade（54°-85°） affected the alternating load, therefore influencing tillage stability. The traction angle, plow tilt angle, and lift angle of the rotary blade were used as the experimental variables, and the stability coefficient under tillage depth-based working conditions and the stability coefficient under tillage width-based working conditions were used as the experimental indicators in a 3-factor/2-level quadratic orthogonal rotating combinatorial test to determine the optimal parameter combination of the influencing factors. Subsequently, the regression equations with the stability coefficient as the objective functions as well as the response surface for the stability coefficient could be obtained by analyzing the test results using the Design-Expert software. The variance analysis showed that among the 3 variables in the test, the plow tilt angle had the greatest influence on the tillage depth and tillage width stability coefficients, while the lift angle of the rotary blade had the least influence on the coefficients. The response surface analysis showed that with a fixed lift angle of the rotary blade of 69.5°, an optimal tillage depth stability coefficient of 91.7% could be obtained with traction angle and plow tilt angle of 23.7° and 26.8°, respectively. An optimal tillage width stability coefficient of 93.2% could be achieved with traction angle and plow tilt angle of 25.2° and 27.3°, respectively. The optimal parameter combination was traction angle of 17.3°, plow tilt angle of 27.8°, and rotary blade＇s lift angle of 72.6°. This optimal combination could achieve the working condition tillage depth stability coefficient of 91.8% and the tillage width stability coefficient of 93.4%, respectively. The validation experiments showed that with the optimal parameter combination of the influencing factors, the working condition tillage depth stability coefficient and the tillage width stability coefficient were 91.5% and 93.1%, respectively; these results were consistent with the ones obtained via software analysis. Other tillage performance indicators of the machine, such as tillage depth, tillage width, surface leveling degree, pulverization rate, and straw coverage rate which were respectively 1.87, 1.98, 21.20, 90.30% and 90.70%, all met the agronomic requirements.