椭圆齿轮行星轮系蔬菜钵苗取苗机构的参数优化与试验

为了得到一种结构简单且具有较高效率的蔬菜钵苗取苗机构,该文在分析国内外多种取苗机构的特点后,提出一种由5个全等椭圆齿轮组成行星轮系的新型取苗机构。根据取苗机构的设计要求,分析了该取苗机构的机构组成、工作原理以及运动学数学模型。进而开发该机构的计算机辅助分析与优化软件,基于该软件分析了机构参数变化对取苗轨迹和取苗臂姿态的影响,确定了取苗机构的优化参数。基于优化所得参数对取苗机构进行三维建模与仿真,研制样机并进行取苗试验,试验结果表明,该取苗机构运转顺畅,取苗成功率95%,满足机械自动取苗的工作要求,验证了取苗机构设计的正确性及可行性。该研究结果为自动移栽机核心工作部件的研发提供参考。

Parameter optimization and test on pick-up mechanism of planetary gear train with ellipse gears for vegetable plug seedling

Abstract: In order to develop simpler and more reliable high-efficiency pick-up mechanism for vegetable plug seedling, a new type of pick-up mechanism, vegetable plug seedling pick-up mechanism of planetary gear train with 5 congruent ellipse gears, was developed. The mechanism consists of transmission part, including ellipse gears planetary gear train, and 2 identical pick-up seedlings arms. Two symmetrically distributed arms permit the mechanism to pick up twice as many as seedling for each rotation of transmission. Comparing to existing pick-up mechanisms, the mechanism is greatly simplified and pick-up efficiency is well improved. In this paper, the requirements of pick-up mechanism as the design basis were introduced and the work principle was clarified. Mechanism imitated artificial action of picking up seedling from seedling tray, holding the seedling moving forward and releasing it into seedling-planting mechanism for the following planting work. Then going back to its original position where ready condition for next picking was set. During the above-mentioned process, a particular locus with 2 remarkably straight and close-set curve part had been formed which sufficiently satisfied the requirement of automatically picking up seedling. In term of the specific action of the finger-like pick-up claws fixed on the mechanical arms picking up seedling, it could be divided into 4 phases. The claws were completely open to stay prepared state for picking up seedling before entering the hole of the seedling plug, started to be clamped slowly when reaching the seedling tray surface, turned to be fully clamped and pulled the seedling out of the hole of the tray when claws entered to the bottom of the hole in the seedling tray, then seedling was hold reliably moving to a particular location where a set of seedling-plant mechanism placed below, and the claws started to open until a new seedling-pick process started. Afterward, based on above analysis of the principle of mechanism, a mathematical equation of mechanism kinematics was established. Therefore, a computer aided analysis and optimization software on the platform of Visual Basic for this vegetable plug seedlings pick-up mechanism was developed on basis of the established mathematical equation. With the man-computer interaction of this visualization software and by using method of controlling single variable at a time, a group of combinative analysis by trial and error was carried out, therefore the regularity of how changes in values of the structure parameters influenced work locus of the mechanism was analyzed in a convenient way. Then, one group of non-inferior parameters that well met the demands of forming ideal work locus in accordance with design requirements were presented. Based on these non-inferior parameters, mechanism 3D model was set up. Subsequently, simulation analysis and prototype test are carried out. It turned out that mechanism run smoothly and the pick-up success rate reached 95%. The mechanism was proved to be suitable, indicating the feasibility of the mechanism's theoretical model. The results will provide technical support for research and development of core components of automatic transplanting machine.