基于贝塞尔曲线的液肥扎穴机构动力学分析与试验

Dynamics Analysis and Test on Picking Hole Mechanism of Liquid Fertilizer Based on Bezier Curve

摘要:

采用贝塞尔理论推导出了非圆齿轮节曲线方程，进而设计了一种贝塞尔节曲线齿轮行星轮系扎穴机构。以扎穴机构为研究对象建立了动力学模型，利用Visual Basic 6.0软件编写动力学软件，得到单位工作周期内各齿轮轴心及啮合点处受力随行星架转角变化的规律。搭建动力学土槽试验台，在工作转速40、60、80r/min，土槽移动速度0.8m/s及土壤硬度0.4~1.0MPa工况下，测定扎穴机构及支撑底座的动力学特性。试验结果表明，随行星架转速增加扎穴机构振动增强；单位工作周期内支撑底座所受反力的变化规律以旋转角180°为中心对称分布。测试结果与理论分析一致，验证了理论模型的正确和试验方法的可行，该研究为施肥机高速作业时的动平衡控制提供了理论依据，为进一步设计高速化轻型化的液态施肥机奠定了基础。

Abstract:

Deepfertilization technology of liquid fertilizer is a kind of agricultural technology which can apply liquid fertilizer accurate quantitatively in deep soil near the roots of crop according to the distribution characteristics of soil nutrient and crops. A type of picking hole mechanism of deep liquid fertilizer with planetary Bezier gears that was designed by using a fitted Bezier curve as a noncircular gear pitch curve was proposed. Taking picking hole mechanism as the research object, a dynamics model was established, thus, the variation law of force both on axle centers and meshing points of gears in a working cycle due to the changing of the rotaryangle of planetary carrier was obtained using Visual Basic software. Soil bin dynamics test bench was also set up. Dynamics properties of picking hole mechanism, spray fertilizer needle and bearing were determined with rotary speed of 40r/min, 60r/min and 80r/min, moving speed of soil bin of 0.8m/s and soil firmness of 0.4~1.0MPa. Experimental results show that vibration of picking hole mechanism was increased with the increase of rotary speed of planetary carrier. With the 180° rotation angle as the center, the reaction force of bearing was symmetrically distributed. The test results were consistent with theoretical analysis, which verified the correction of theoretical models and the feasibility of test method. This research provides a theoretical foundation to dynamic balance control of the liquid fertilizer applicator during highspeed operation, and lays a foundation for the further design of high speed and lightduty machine. 