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.

Reverse Design and Test of Non-circular Gear & Crank-Rocker & Gear Trains Weft Insertion Mechanism

For the purpose of obtaining satisfactory performance of the non-circular gear & crank-rocker & gear trains (NCCRG) weft insertion mechanism which was proposed in this paper, the ideal kinematic curve of this weft insertion mechanism was given, and the reverse solution models of this mechanism were established. A reverse design and simulation software was compiled based on Visual Basic 6.0 to obtain the mechanism parameters, including the pitch curves and tooth profiles of the non-circular gears. A test-bed of this mechanism was developed according to these parameters. The kinematic performance of this weft insertion mechanism was tested by high-speed video tape recorder with its corresponding video analytical software Blaster's MAS. And the test results were identical with the theoretical calculation. Compared with the conjugate cam weft insertion mechanism which is applied on TT96 rapier loom, under the condition of same weft insertion rate, the variation of acceleration of this mechanism is smaller. This novel weft insertion mechanism can meet the requirements of weft insertion on rapier looms with smooth and steady motion.

蔬菜移栽机斜齿轮-非圆齿轮行星轮系取苗机构研究

针对完全非圆齿轮行星轮系取苗机构存在推苗角不够大,而不完全非圆齿轮轮系取苗机构存在冲击的问题,本文设计了一种满足蔬菜移栽取苗要求的具有较大推苗角的非圆完全齿轮行星轮系取苗机构。基于傅里叶函数设计了一种二次不等幅传动比曲线,开发取苗机构设计分析软件,分析傅里叶系数对取苗轨迹的影响规律,研究傅里叶系数对传动比曲线及从动轮和秧针速度特性的影响,揭示傅里叶系数对取苗机构运动学参数的影响规律,推导了不同傅里叶系数时取苗机构取苗角和推苗角的变化规律。制造和装配取苗机构,基于虚拟样机、高速摄像技术对取苗机构进行了旋转试验,通过对比取苗轨迹的理论、仿真和试验值一致性验证了取苗机构设计的可行性。对取苗机构进行了台架取苗试验,得出转速40、50、60 r/min时取苗机构的取苗成功率分别为94%、90%和88%,通过取苗试验进一步验证了取苗机构设计的可行性。

偏心齿轮-非圆齿轮行星系取苗机构的运动学建模与参数优化

针对目前蔬菜移栽作业中半自动移栽机需要人工喂苗、工作效率低等缺点,以及日本自动移栽机的复杂结构、高制造成本和工作效率不高等问题,设计了一种应用于蔬菜钵苗自动移栽机的偏心齿轮-非圆齿轮行星系自动取苗机构。在分析该旋转式自动取苗机构的结构特点和工作原理的基础上,建立了机构的运动学模型,开发了基于Visual Basic6.0的计算机辅助分析与优化软件对机构的结构参数进行优化。通过人机交互优化方法,得出了结构参数对取苗臂尖点运动轨迹和优化目标的影响规律,进而优化得到满足蔬菜钵苗自动取苗要求的机构结构参数。

椭圆—不完全非圆齿轮行星系蔬菜钵苗取苗机构的研究

在分析现有蔬菜钵苗取苗机构的最新进展的基础上,提出一种应用于自动蔬菜移栽机的新型取苗机构——基于椭圆—不完全非圆齿轮传动的行星系蔬菜钵苗取苗机构。分析蔬菜钵苗取苗机构所要求的工作轨迹与设计要求,介绍该取苗机构的工作原理和运动学特性,建立该取苗机构的运动学模型。基于Visual Basic 6.0开发出该取苗机构计算机辅助分析与优化软件,通过人机交互方式优化出一组满足蔬菜钵苗取苗机构工作要求的结构参数。根据优化出的结构参数对该取苗机构进行三维建模、虚拟仿真、样机试验,试验发现:仿真结果、样机试验结果与理论分析结果一致;同时,进行该蔬菜取苗机构的取苗试验,该取苗机构能很好地完成取苗、持苗、放苗动作,进一步验证该取苗机构理论建模的正确性和可行性。

一种旋转式穴盘苗取苗机构的设计

分析现有穴盘苗取苗机构的发展现状,提出一种新型的旋转式穴盘苗取苗机构。依据旋转式穴盘苗取苗机构的结构特点及工作原理,选取三段合适的传动比函数,构建一种新型非圆齿轮的节曲线方程,建立该穴盘苗自动取苗机构的运动学模型。开发该取苗机构的计算机辅助分析软件,通过人机交互方式得出一组满足旋转式穴盘苗取苗机构工作要求的结构参数。基于参数对该取苗机构进行了设计,提出一种能够实现变化范围较大变速传动的新型非圆齿轮。对新型非圆齿轮完成结构设计及试验,验证了新型非圆齿轮的可行性。通过分析虚拟仿真得到的工作轨迹及取苗爪尖点的速度曲线,验证该取苗机构的可行性及工作的平稳性。

蔬菜钵苗旋转式取苗机构动力学分析与试验

针对一种应用于蔬菜钵苗全自动移栽机的旋转式取苗机构——偏心齿轮-非圆齿轮行星系取苗机构,建立机构的动力学模型,采用动力学方程组序列求解法进行求解,得到机构在一个工作周期内链条、太阳轮轴心、中间轮轴心、行星轮轴心、太阳轮与中间轮啮合点、中间轮与行星轮啮合点等处的受力随行星架转角变化的规律。设计了机构的物理样机,开展机构动力学试验,测试得到机构物理样机在4种不同工作转速下的动力学特性,同时验证了机构动力学模型的正确性。

二阶自由非圆齿轮行星系钵苗移栽机取苗机构

为满足旱田钵苗移栽取苗机构理想鹰嘴形工作轨迹要求,提出了连续传动的二阶自由非圆齿轮行星轮系取苗机构,以实现取苗爪周期性二次不等幅摆动规律。利用曲线拟合方法构建自由传动比函数,建立机构不等速传动的数学模型,编写机构分析软件,确定传动比函数和机构参数,研制取苗机构并进行了高速录像试验。结果表明,该型取苗机构的工作轨迹和理论计算吻合,能够实现取苗深度35 mm,取苗爪在钵体中穴口小于5 mm,取苗爪入钵和出钵段姿态满足工作要求。

组合式非圆齿轮行星轮系取苗机构动力学分析与试验

针对组合式不完全偏心圆-非圆齿轮行星轮系旋转式取苗机构,应用动态静力分析法和动力学方程组序列求解法,建立机构动力学模型,开发出机构动力学分析软件求解模型,计算得到机构链条受力、各齿轮旋转中心和啮合点受力、支座反力的变化规律;建立了机构虚拟样机,加工出机构物理样机,开展机构动力学仿真分析和台架试验,得到两种情况下机构转速为60 r/min时支座反力与行星架转角之间的关系,取苗机构理论分析、仿真分析和台架试验所得到的支座反力变化规律基本一致,验证了取苗机构动力学模型的可靠性和动力学分析的正确性;与原取苗机构比较,本文取苗机构样机y方向支座反力的最大幅值和方差分别从155 N和1 171 N2减小为77 N和553 N2,降低了50. 3%和52. 7%,表明提出的取苗机构具有比原机构更优的动力学性能。

非规则齿轮行星系扎穴机构反求设计与试验

针对现有扎穴机构存在扎穴穴口大、入出土垂直度差等问题,设计了一种深施型液态施肥机非圆齿轮行星系扎穴机构。为使扎穴机构得到满足农艺要求的入出土垂直度,提出了一种基于Matlab GUI开发平台的非圆齿轮行星系扎穴机构反求设计与运动学仿真分析方法。通过微调静轨迹曲线上的少量型值点,得到了一组机构最佳优化参数,应用Pro/E软件建立扎穴机构模型,并利用ADAMS软件对其进行模拟仿真,得到喷肥针尖点运动轨迹曲线。试验台试验结果表明:穴口宽度为30.3 mm、穴距为221.9 mm,该扎穴机构能够满足喷肥针入出土垂直度好、穴口小的设计要求。

非圆齿轮引纬系统

利用非圆齿轮与连杆机构串联组合可以得到所需运动规律的优点,这里提出了用非圆齿轮机构引纬的新思想,并完成了一个引纬系统实例的设计计算。