Design and Experimental Research on Seedling Pick-Up Mechanism of Planetary Gear Train with Combined Non-circular Gear Transmission

Currently, transplanting mechanisms for dryland plug seedlings in China are mainly semiautomatic and have low efficiency. The rotary seedling pick-up mechanism with a planetary gear train for non-uniform intermittent transmission, and a concave and convex locking arc device, has a large rigid impact. To solve these problems, according to the design requirements for a dryland plug seedling transplanting mechanism, a rotary seedling pick-up mechanism of a planetary gear train with combined non-circular gear transmission of incomplete eccentric circular and noncircular gears was proposed. This has the characteristics of two-times greater fluctuation of the transmission ratio in a cycle, and can achieve a non-uniform continuous drive. Through analysis of the working principle of the seedling pick-up mechanism, its kinematics model was established. The human–computer interaction optimization method and self-developed computer-aided analysis and optimization software were used to obtain a set of parameters that satisfy the operation requirements of the seedling pick-up mechanism. According to the optimized parameters, the structure of the seedling pick-up mechanism was designed, a virtual prototype of the mechanism was created, and a physical prototype was manufactured. A virtual motion simulation of the mechanism was performed, high-speed photographic kinematics tests were conducted, and the kinematic properties of the physical prototype were investigated, whereby the correctness of the theoretical model and the optimized design of the mechanism were verified. Further, laboratory seedling pick-up tests were conducted. The success ratio of seedling pick-up was 93.8% when the seedling pick-up efficiency of the mechanism was 60 plants per minute per row, indicating that the mechanism has a high efficiency and success ratio for seedling pick-up and can be applied to a dryland plug seedling transplanter.

Mathematic model and tooth contact analysis of a new spiral non-circular bevel gear

A novel spiral non-circular bevel gear that could be applied to variable-speed driving in intersecting axes was proposed by combining the design principles of non-circular bevel gears and the manufacturing principles of face-milling spiral bevel gears.Unlike straight non-circular bevel gears,spiral non-circular bevel gears have numerous advantages,such as a high contact ratio,high intensity,good dynamic performance,and an adjustable contact region.In addition,while manufacturing straight non-circular bevel gears is difficult,spiral non-circular bevel gears can be efficiently and precisely fabricated with a 6-axis bevel gear cutting machine.First,the generating principles of spiral non-circular bevel gears were introduced.Next,a mathematical model,including a generating tooth profile,tooth spiral,pressure angle,and generated tooth profile for this gear type was established.Then the precision of the model was verified by a tooth contact analysis using FEA,and the contact patterns and stress distributions of the spiral non-circular bevel gears were investigated.

Design and Experiment of Non-circular Combined Gear Train Beating-up Mechanism

The most important performance of a beating-up mechanism is that the dwelling time of the sley must ensure the completion of the weft insertion. To meet this requirement, a new non-circular combined gear train beating-up mechanism which is composed of two-stage planetary gear trains is proposed. The first-stage is a Fourier planetary gear train and the second-stage is a non-circular planetary gear train. For designing of this new mechanism, the ideal kinematic equations of the sley are constructed first. Then the kinematic model of the first-stage Fourier planetary gear train is established and the reverse solution for the pitch curves of the second-stage non-circular gears is deduced. With a computer-aided design program, the influences of several important parameters on the pitch curves of the second-stage non-circular gears are analyzed, and a set of preferable structural parameters are obtained. Finally, a test bed of this mechanism is developed and the experimental results show that this new beating-up mechanism can achieve the designed dwelling time, namely it can meet the requirements of beating-up process.

Research on stepless transmission utilizing noncircular gears

In view of the lack of systemic analysis for stepless transmission using noncircular gears, two basic noncircular gear units, an addition unit adopting differential mechanism and a multiplication unit applying a fixed gear train, are proposed. Then, the design methods of the noncircular gear pair of each unit, transmission ratio relationship, rotation angle relationship and key parameters with specific physical meanings are studied. The adjusting properties, composing strategy and varying range of transmission ratio etc. are investigated in detail for each unit. Following this, several examples of using a noncircular gear pair in the units and their manipulation technique are introduced.

Calculating method of contact stress for non-circular gears

According to Hertz theory, the difference of contact stress for non-circular gears and equivalent gears is compared in the paper, a calculating method of contact stress for non-circular gears by using equivalent gears is researched, and computing formulas of power and rotation speed for equivalent gears are deduced. A numerical simulation of contact stress for non-circular gears has also been conducted based on the finite element method. By the comparison of fitting curves, the feasibility of using equivalent gears instead of non-circular gears to calculate the contact stress is testified.

Research on Design Method of Non-Circular Gear Pair with Double Generating Angles

In order to enhance the bearing capacity of non-circular gear pair, the non-circular gear pair with double generating angles is proposed based on the design idea of unsymmetrical gear with double pressure angles. The tooth profile is designed by generating cutting theory, the pure rolling mathematic model that the center line of unsymmetrical rack roll along non-circular pitch curve is built, the digital model of non-circular gear with double generating angles is created through the second development method of CAD software, and then the drive characteristic and tooth strength are analyzed. The results show that the design method for double generating angles non-circular gear proposed in this paper is feasible, which is significant to improve the bearing capacity of non-circular gear pair.

取秧侧向零偏移的空间轨迹再生稻分插机构设计与试验

为了解决现有空间行星轮系式分插机构在再生稻宽窄行机械化种植取秧过程中出现侧向偏移量和侧向偏转角的技术难题,本文提出一种具有局部平面轨迹特性的空间轨迹不等速行星轮系机构,并开展基于取秧口和机构回转中心位置约束下的宽窄行分插机构综合研究。构建了基于关键位姿点(取秧起始点、取秧结束点、推秧点)的空间轮系机构运动综合模型,利用关键位姿点求解机构杆长参数与空间交错轴信息,并通过优选二杆相对角位移参数实现机构传动比分配。将不完全非圆齿轮副引入空间行星轮系机构,利用间歇机构锁止弧约束行星轴,实现机构取秧过程侧向零偏移量、侧向零偏转角的平面轨迹段。通过仿真分析与机构样机试验验证了机构实际作业性能与理论设计相一致,结果表明:分插机构取秧侧向零偏移量,取秧侧向零偏转角,推秧侧向总偏移量为50.24 mm、取秧角为5.18°、推秧角为71.56°、推秧侧向角为16.26°、插秧穴口宽度为22.43 mm、轨迹高度为289.76 mm,满足预期设计要求。最后通过田间试验验证,分插机构可实现等行距取秧口和既定机构回转中心下宽行(40 cm)与窄行(20 cm)间隔机插,满足再生稻宽窄行种植要求。

非圆齿轮滚齿切削力波动特性及抑制研究

滚齿是非圆齿轮加工实现的重要方法,用于节曲线外凸直或斜齿非圆齿轮的高效高精制造,节曲线非圆特性导致滚切力呈现较大幅度波动,影响制造过程稳定性及加工精度,是非圆齿轮滚齿领域需要研究的重要课题。文章基于单位切削力计算原理及圆柱齿轮滚切力的研究成果,采用单次断续切削产生的未变形切屑体积表征滚切力波动态势,构建非圆齿轮滚切未变形切屑模型的获取方法。选取大偏心率卵形齿轮为研究对象,分析滚刀恒速不窜刀联动加工模型所产生的滚切力波动特性,得出该联动加工模型所对应峰值切削力的波动规律。提出一种滚刀恒速并附加窜刀的联动加工模型,该模型具有恒定弧长增量加工特性,对抑制整周滚切力波动具有重要意义,并开展不同滚切深度所对应滚切力波动规律研究,研究结果为非圆齿轮滚切方案的优化制定提供一定的理论依据。

高阶多段变性巴斯噶蜗线齿轮的设计与分析

针对高阶变性巴斯噶蜗线齿轮变性段数量有限,传动比调节能力差的问题,提出了一种高阶多段变性巴斯噶蜗线非圆齿轮传动形式。研究了高阶多段变性巴斯噶蜗线非圆齿轮的形成机理,推导出了巴斯噶蜗线非圆齿轮的统一数学表达式,并对其传动特性进行了详细讨论。利用MatLab软件编写了可视化的高阶多段变性巴斯噶蜗线非圆齿轮分析设计软件及非圆齿轮齿廓生成软件,并通过设计实例予以验证,实例表明,高阶多段变性巴斯噶蜗线非圆齿轮在实际应用中是可行的。

非圆齿轮电火花线切割加工工艺参数对齿廓误差的影响

线切割加工非圆齿轮时电参数是影响齿廓误差的关键因素之一.设计正交试验,分别采用非圆齿轮齿根、齿廓中部和齿顶的最大齿廓误差对线切割加工非圆齿轮进行分析.通过方差分析方法和主效应分析法,研究线切割加工电参数峰值电流、脉冲宽度、脉冲间隔和跟踪对非圆齿轮齿根、齿廓中部和齿顶的齿廓误差影响规律.同时,对齿廓误差、加工时长和工艺参数进行回归分析,并建立回归模型,基于灰狼优化算法对回归模型进行多目标优化求解.通过研究结果可以得出线切割加工非圆齿轮齿廓不同部位的最优参数组合,可为实际加工提供参考.

高接低栽式差速变姿态行星轮系栽植机构设计与试验

针对目前旱地蔬菜钵苗移栽机大多适用于大株距(大于260 mm)移栽且投接苗与栽植位置作业高度差大、移栽性能不佳等问题,本文提出一种高接低栽式差速变姿态行星轮系栽植机构。根据中小株距蔬菜钵苗移栽农艺指导与机构设计要求,解析双行星架差速行星轮系栽植机构工作原理并建立其运动学理论模型;结合所提出优化目标构建目标函数,开发了基于Matlab GUI的栽植机构计算机辅助分析优化设计软件,通过人机交互方式获得1组较优的机构设计参数组合。通过三维建模与装配以及ADAMS软件虚拟仿真,初步验证了机构正确性与合理性。开展栽植机构物理样机试制与试验台架系统开发研究,通过空转试验测试,验证了栽植机构实际作业轨迹、姿态与虚拟仿真及理论设计的一致性;开展栽植机构接苗与栽植性能试验,试验结果表明,栽植机构在接苗与栽植各项试验指标均较为优秀,能够满足栽植机构预期设计要求与旱地移栽机械标准,验证了该机构的可行性与实用性。

一种新型高阶齿扇齿条副的啮合性能分析

目前汽车转向器非圆齿轮副普遍采用C^(0)阶连续的变传动比曲线,其齿扇齿廓有尖点,不光滑,速度和加速度有突变,传动不够平顺。为此,以四次多项式为基函数设计C^(2)阶连续的变传动比曲线,采用齿廓法线法求解不同连续阶的齿扇齿廓,基于有限差分法推导齿廓曲率的计算公式,对比分析C^(0)、C^(1)、C^(2)阶传动比曲线的齿廓结构特点、传动中的速度与加速度的变化特点以及其齿廓光滑性。仿真结果表明汽车转向器非圆齿轮副传动比曲线的连续阶越高,其齿廓越光滑。

非圆齿扇齿条副齿面接触应力分析及仿真

针对汽车转向器摇臂轴非圆齿扇的工作齿面易发生磨损、点蚀甚至断裂等现象,围绕非圆齿扇齿条副的齿面接触应力理论建模与有限元仿真分析开展研究,提出一种非圆齿扇齿条副接触应力理论计算模型,研究齿扇齿宽B、齿条压力角α和齿扇锥角φ等几何参数对齿面接触应力的影响规律;将非圆齿扇齿条副三维参数化建模与齿面动态啮合有限元仿真分析集成,提出一种非圆齿扇齿条副接触应力参数化、全流程仿真分析计算方法。预期为汽车转向器非圆齿扇齿条副的设计分析提供理论和方法指导。

非圆齿轮-连杆组合式水稻钵苗膜上移栽机构优化设计与试验

为实现机械化一体式水稻钵苗膜上移栽要求,提出非圆齿轮-连杆组合式行星轮系移栽机构,用一套机构实现取苗、送苗、破膜挖穴和栽植4个工序协同配合作业,满足水稻钵苗膜上移栽所需的轨迹与姿态要求。对移栽机构进行理论分析并建立运动学模型,结合优化目标,基于Matlab GUI平台开发了数字可视化优化设计软件,通过人机交互获得1组满足移栽要求的机构参数。根据优化参数对机构开展结构设计与三维建模,通过ADAMS软件完成了虚拟样机仿真验证。研制了水稻钵苗膜上移栽机构物理样机与多功能试验测试台架,开展了移栽机构在空转和带苗状态下运动学特性和工作性能试验,结果表明,理论轨迹、虚拟样机仿真轨迹和物理样机台架试验轨迹在误差允许范围内保持一致,验证了移栽机构设计的一致性与正确性,性能试验结果:取苗成功率为94%,移栽成功率为92.36%,栽植株距变异系数为2.67%,满足移栽作业要求,验证了水稻钵苗膜上移栽机构设计的合理性与可行性。

行星轮系取栽一体化蔬菜移栽机构优化设计及试验

为简化蔬菜毯苗移栽机构、提高移栽效率,提出了一种非圆齿轮行星轮系和变形椭圆行星轮系组合的取苗挖穴一体化移栽机构,可完成蔬菜毯苗切块、取苗、送苗、挖穴、投苗的工作过程。首先,根据蔬菜毯苗的农艺要求,选取合适的移栽轨迹,设定精确位姿点,采用运动生成机构综合方法建立取苗机构运动学模型;根据取苗机构的运动轨迹要求,基于求解参数拟合优化,获得输入轴与输出轴转角关系曲线,计算非圆齿轮行星轮系总传动比和非圆齿轮节曲线参数。其次,确定挖穴机构优化目标,获得挖穴机构参数。最后,完成整套机构组合与三维模型装配,并进行仿真和样机试验。结果表明,理论轨迹、仿真轨迹和试验轨迹基本一致,幼苗移栽平均漏栽率为2%,平均倒伏率、伤苗率、埋苗率均为1.5%,均满足农艺要求,验证了机构设计方法的准确性。

游梁式抽油机非圆齿轮传动设计与节能分析

[目的]针对游梁式抽油机存在系统效率低、能耗高、负载波动大的不足,对基于非圆齿轮传动的游梁式抽油机节能设计方案进行研究.[方法]在考虑非圆齿轮传动条件及其与曲柄载荷匹配原则的基础上,选取最优非圆齿轮节曲线,形成非圆齿轮节曲线的节能设计准则.通过仿真分析,获得不同非圆节曲线对应的能耗值,筛选出最低能耗对应的非圆节曲线,并结合CYJY10-4.2-53HB型号游梁式抽油机进行仿真和实验验证.[结果]1)仿真结果得到在同功率电机下耗能降低4.7%,在更小功率电机下耗能降低11%,与实验结果基本一致;2)基于非圆齿轮传动的游梁式抽油机,可大幅度降低抽油机输入轴的扭矩峰值和扭矩波动,降低能耗,实现节能.[结论]从节能和降低负载波动的角度来看,非圆齿轮传动对于圆柱齿轮更有优势.

非圆面齿轮限滑差速器的设计方法与锁紧特性

文中提出了一种基于非圆面齿轮的新型变传动比差速器,具有互换性好、容错性能强的突出优势,针对该差速器的构型设计与转矩分配特性展开研究。在阐明非圆面齿轮传动机理的基础上,给出了非圆面齿轮的传动比函数与齿数配比方法;结合非圆面齿轮的传动特性和变传动比差速器的机构原理,给出了非圆面齿轮差速器的构型设计方法,并推导出非圆面齿轮差速器锁紧系数表达式,仿真结果表明:增大非圆面齿轮的偏心距有利于提高非圆面齿轮差速器锁紧系数,但考虑非圆面齿轮差速器的体积及轮齿缺陷,需要对非圆面齿轮差速器偏心距进行限制;最后,根据非圆面齿轮设计方法完成了样机研制,测得实际锁紧系数为2.32,与理论计算结果基本吻合。

非圆行星齿轮马达设计与排量分析

非圆行星齿轮马达具有容积效率高、密封性良好、传递扭矩大等优势,可应用于井下机械和食品机械等领域。根据几何关系推导圆弧-圆弧型(双圆弧型)节曲线参数所需满足的弧长条件、传动条件与约束条件,建立并求解内齿圈与太阳轮节曲线非线性规划模型。在分析非圆行星齿轮马达进排液规律的基础上,确定不同太阳轮旋转角度下各容腔进排液的周期变化规律。通过面积拟合法与图解法求解马达最大与最小容腔面积,确定马达理论排量。非圆行星齿轮马达试验测试结果表明,试验法与理论计算法确定的马达实际流量随转速变化的趋势基本一致,最大误差仅为9.57%,验证了双圆弧型节曲线马达理论排量模型的正确性,可为进一步探索非圆行星齿轮马达优化设计提供参考。

不完全非圆齿轮行星轮系水稻钵苗移栽机构的动态特性研究

针对水稻钵苗移栽机构长期工作后因夹苗片松弛导致取苗准确率下降的问题,考虑齿轮的时变啮合刚度,对移栽机构展开动态特性研究。首先,将不完全非圆齿轮等效为圆柱齿轮,采用改进势能法对两级不完全非圆齿轮副的时变啮合刚度进行求解;建立移栽机构的弹性动力学模型,完成移栽机构模态分析。然后,采用RecurDyn建立移栽机构的动力学仿真模型,完成移栽机构模态仿真,获得了机构的前8阶固有频率与振型;对夹苗片进行动力学仿真分析,获得了夹苗片的应力变化。最后,测试并编制夹苗片的工作载荷谱,进行夹苗片疲劳寿命计算。结果表明:移栽机构前8阶固有频率的理论计算结果与仿真计算结果基本一致,第1阶固有频率最小值为112.3 Hz,振型为夹苗片的弯曲变形;夹苗片的弯曲部分应力最大,为355.6 MPa;夹苗片的疲劳寿命为19.4 h,远低于实际使用要求;更换夹苗片材料,试验结果表明夹苗片疲劳寿命大于200.0 h,满足移栽机构长期工作的需求。该研究可为不完全非圆齿轮副的时变啮合刚度计算提供理论依据,促进移栽机构动态特性研究的进程,同时也为移栽机构的优化设计提供技术支持与参考。

数学建模在水稻插秧机作业优化中的应用

为了降低插秧机的作业故障次数、提升插秧效率和插秧质量,对数学建模在水稻插秧机作业优化中的应用进行了研究。为了有效提升作业效率和作业质量,分插机构的传动部件改进为非圆齿轮行星系,并针对传动装置建立数学模型并分析。为了验证水稻插秧机的结构是否合理,对其进行了仿真试验,结果表明:水稻插秧机的结构合理,可将其应用于实际生产。