【作者】 王英；

【导师】 陈建能；

【作者基本信息】 浙江理工大学 ， 机械设计及理论， 2014， 博士

【摘要】 育苗移栽具有对气候的补偿作用和使作物生育提早的综合效益。但是由于我国旱地栽植机械发展较慢，移栽作业仍以人工为主，移栽机械化程度最高的棉花也不足30%。随着我国大力发展效益农业，能够实现高立苗率和低损伤率的旱地高速移栽机械已成为发展趋势。栽植机构是将钵苗植入大田的最终机构，是移栽机的两大核心机构之一，其作业性能直接影响整台移栽机的作业性能和竞争力。因此对栽植机构进行理论和试验研究，为旱地高速移栽机械的研发提供理论基础和设计依据，具有重要的实用价值和理论意义。栽植机构的理想要求是高立苗率和低损伤地高速栽植。传统的保证立苗率的“零速度”移栽理念在实际作业时很难实现，且传统的栽植机构不能满足高速移栽要求，针对这些问题，本论文提出通过保证栽植嘴理想轨迹、姿态、速度和挖出的穴口形状等运动学特性来提高立苗率和降低损伤率的新思路，并在该思路指导下开展基于非圆齿轮行星传动的栽植机构研究。本文主要的研究内容和结果如下：1）研究国内外各种类型栽植机构的工作原理并分析其存在的问题，总结满足高立苗率和低损伤地高速移栽对栽植机构的要求，为此本文提出基于非圆齿轮行星传动的栽植机构（以下简称非圆齿轮行星轮系栽植机构），并按不同类型的非圆齿轮（椭圆类非圆齿轮、偏心圆类非圆齿轮、傅里叶类非圆齿轮、巴斯噶蜗线类非圆齿轮）传动进行组合设计，共构成25种不同栽植机构；在分析非圆齿轮副传动特性的基础上，建立了栽植机构的运动学数学模型和动力学数学模型，并编写了运动学和动力学特性辅助分析软件，得到栽植机构的运动学和动力学特性。2）为减少栽植过程中钵苗损伤，提高移栽成功率，以西兰花钵苗为移栽对象，设计正交试验研究不同穴盘规格、不同含水率和不同苗龄西兰花钵苗的机械特性，包括土钵的抗压强度、钵苗相对栽植嘴壁面的摩擦系数和钵苗与栽植嘴碰撞时不回弹的相对速度，分析这些因素对钵苗损伤的影响，采用综合评分法并从经济角度考虑，获得适合西兰花钵苗机械化栽植作业的物理特性：128穴盘、5~6片真叶、含水率50%和128穴盘、2~3片真叶、含水率63%，并为构建栽植作业时栽植嘴的理想姿态和速度提供依据。3）分析栽植作业过程中钵苗与栽植嘴的相对运动，结合西兰花钵苗的物理机械特性和栽植机构的运动学模型，建立钵苗相对栽植嘴的运动微分方程，并编写西兰花钵苗运动辅助分析软件，得到作业过程中西兰花钵苗与栽植嘴之间的相对运动和相互作用力，为栽植机构动力学特性分析的假设条件提供理论依据。结果表明：在进行栽植机构动力学特性分析时，可忽略钵苗的影响。4）以西兰花钵苗物理机械特性为约束条件，并结合栽植农艺要求，建立一个作业循环内栽植嘴理想轨迹、姿态、速度和挖出的穴口形状等运动学特性要求的理论模型。以理想运动学特性要求为目标，根据所建立的栽植机构运动学模型和西兰花钵苗的运动微分方程，建立栽植机构运动学特性多目标参数优化模型；采用matlab遗传算法工具箱对每一种非圆齿轮行星轮系栽植机构进行运动学优化，找到满足理想运动学特性要求的每种栽植机构的参数范围。5）以所建立的栽植机构动力学模型为基础，构建动力学特性评价准则，以运动学的优化结果为约束条件建立动力学特性多目标参数优化模型；同样采用遗传算法进行动力学寻优，得到最佳栽植机构类型及其对应的机构参数：第一级齿轮副为偏心圆类非圆齿轮，第二级齿轮副为椭圆类非圆齿轮，机构参数为栽植嘴的初始安装角θ=114.256，两级非圆齿轮转动中心连线的夹角γ=30.834，齿轮3初始相位角α=25.467，齿轮6初始相位角β=1.375，太阳轮3偏心圆半径R3=30.916mm，太阳轮3偏心距e3=5.583mm，太阳轮3变性系数m31=1.542，中间轮6椭圆长轴半径A6=30.694mm，中间轮6偏心率k6=0.031，中间轮6变性系数m61=1.26。6）根据优化得到的最佳栽植机构类型及其对应的机构参数，进行栽植装置样机的结构设计和三维模型。研制栽植装置运动学和动力学特性测试试验台，测试空载时栽植装置的运动学（轨迹、速度）和动力学特性，验证所建立的数学模型的正确性；研制栽植装置模拟田间栽植试验台，基于课题组研制的轮胎摩擦驱动旋转式环形土槽进行栽植装置的模拟田间栽植试验，测试株距、栽植深度、栽植嘴张开时刻和西兰花钵苗的穴盘规格、苗龄、含水率对栽植装置田间作业性能的影响。结果表明：当株距在280mm~380mm之间，栽植深度在45mm~55mm之间，选用128穴盘，苗龄为2~3片真叶，含水率为63%的钵苗时立苗率较高，约为95%。更多还原

【Abstract】 Seedling transplantation can compensate the climate and improve the comprehensivebenefit to crop growth in early. However, because of dry land transplanting machinery developsslowly in China, transplanting is still mainly manually performed, even the mechanicaltransplanting rate of cotton is less than30%, which in fact has the highest degree ofmechanization. With the vigorous development of China’s profitable agriculture, transplanter thatcan achieve a high seedling erectness rate and low damage rate in high speed has become thetrend of development. Transplanting mechanism is ultimate mechanism that has seedling plantedin the field, it is one of the two core mechanisms of the transplanting machine, whose behaviordirectly affects the performance and competitiveness of the whole transplanter. Therefore, thetheoretical and experimental research on transplanting mechanism, which can provide thetheoretical basis and design basis for the research and development of high speed transplanter,has important practical value and theoretical significance.The ideal requirements of planting mechanism are high seedling erectness rate and lowdamage rate in high speed. The traditional planting concept "zero-speed" is very difficult toachieve those goals in actual practice, and the traditional transplanting mechanism can not meetthe high-speed transplanting requirements either. Aiming at these problems, this paper putsforward one kind of new ideas that by ensuring the kinematic characteristics of desired trajectory,gesture, velocity of planting nozzle and the shape of the opening to improve the seedlingerectness rate and reduce the damage rate, and under the guidance of this idea, research ontransplanting mechanism based noncircular gear planetary transmission was carried out. Themain research contents and results are as follows:1) Study the working principle of various types of transplanting mechanism both home andabroad, and analyze their problems. Summarize the requirements for planting mechanism thatcan meet the condition of high seedling erectness rate and low damage rate. Thus transplantingmechanism of non-circular gear planetary transmission was proposed in this paper. Mechanismsynthesis was carried out according to the different types of non circular gear (noncircular gearof ellipse, eccentric-circle, Fourier plot, Pascal curve) transmission.25different types oftransplanting mechanism was proposed in total. On the basis of the analysis of noncircular gearpair transmission characteristics, the kinematics and dynamics models of the transplantingmechanism were established. Kinematics and dynamics auxiliary analysis software was alsodeveloped, getting the kinematics and dynamics characteristics of transplanting mechanism.2) In order to reveal the mechanism of seedling’s injury, broccoli was chosen as the researchobject, an orthogonal test was designed to study the mechanical characteristics of broccoli seedling with different tray specifications, different water content and different ages, includingthe anti-press strength of soil bowl, the friction coefficient between seedling and planting nozzlewall, and the relative velocity which keeps the seedling do not rebound after colliding theplanting nozzle. Analyze the influence of these factors imposed on the seedling injury, using thecomprehensive evaluating method and considering in financial terms, the physical characteristicsof broccoli seedling were obtained which were suitable for mechanical transplanting operation:128hole plate,5~6leaves, water content of50%and128hole plate,2~3leaves, water content of63%, and they provide a basis for the subsequent construction of ideal gesture of planting nozzleand speed of plant operation.3) Analyze the relative movement in the process of transplanting between seedling andplanting nozzle, combined with the kinematics model of transplanting mechanism and thephysical and mechanical properties of broccoli seedling, the differential equations of seedling’smotion relative to the planting nozzle was established, kinematics aided analysis software wasdeveloped, and get the kinematics characteristics of broccoli finally.4) Using the physical and mechanical properties of broccoli seedling as the constraintconditions, and combining with the agronomic requirements, theoretical model of desiredtrajectory, gesture, velocity of planting nozzle and the shape of the opening in one working cyclewas built. A multi-objective optimization model of kinematic characteristics of plantingmechanism aimed at ideal kinematic characteristics was established, based on the kinematicmodel of planting mechanism and the kinematic differential equations of broccoli seedling.Using Matlab genetic algorithm toolbox to optimize each kind of non-circular gear planetarysystem transplanting mechanism, finding the parameter range that can meet kinematicscharacteristics requirement for each transplanting mechanism.5) Based on the dynamics model established before, the criteria for evaluation of dynamiccharacteristics were constructed, based on kinematic optimization results as constraint conditions,dynamic multi-objective optimization model was established. The best type of transplantingmechanism and its corresponding parameters were obtained by similarly using the geneticalgorithm for dynamic optimization: the eccentric type of non-circular gear was used as the firstgear pair, and the elliptical non-circular gear was used as the second gear pair, the mechanismparameters are as follows: the initial installation angle of planting nozzle θ=114.256, theangle between the center line of two non-circle gear pair γ=30.834, the initial phase angle ofgear3α=25.467, the initial phase angle of gear6β=1.375, the eccentric circle radius of thesun gear3R3=30.916mm, the offset of sun gear3e3=5.583mm, the deformation coefficient of sun gear3m31=1.542, the radius of ellipse major axis of mid-gear6A6=30.694mm, theeccentricity ratio of mid-gear6k6=0.031, the deformation coefficient of mid-gear6m61=1.26.6) The structure of the mechanism was designed according to the optimum type and thecorresponding optimized mechanism parameters offered by the optimization, and3D model wasbuilt; Test stand has been developed, it can test the kinematics(trajectory, velocity) and dynamiccharacteristics of the transplanting mechanism under the condition of no-load, verifying thecorrectness of the established mathematical model; experiment of simulating the field plantingwas conducted on the rotating test stand, testing the effect of space, depth, specification ofbroccoli seedling,seedling stage and the rate of water content that was composed on the fieldoperation performance of transplanting mechanism. The results showed that the seedlingerectness rate could reach a comparative high level about95%when it met the followingcondition: the space was about280mm~380mm, the depth was about45mm~55mm,128holeplate,2~3leaves, water content of63%.更多还原