蔬菜组合盘钵体苗全自动移栽机关键部件设计与试验研究

发布时间：2018-06-03 23:36

本文选题：移栽 + 组合式穴盘　；参考：《中国农业大学》2017年博士论文

【摘要】：蔬菜在人们膳食结构中占有十分重要的地位,是人体需要的维生素和矿物盐的重要来源。蔬菜生产是农业产出的重要组成部分,已成为中国农业及农村经济的支柱产业。蔬菜移栽可以节省农时、提高产量和品质。全自动移栽机的使用可以解决蔬菜移栽环节出现的用工紧缺,成本高,效率低等问题。本文提出一种新的取苗方式,并针对全自动移栽机的核心部件进行设计和优化,在以下几个方面进行了相关试验与研究:1.对钵苗形态尺寸、基质的抗压性能、顶出力、摩擦系数、抗跌碎性能进行试验和测量,研究可能影响取苗效果的相关钵苗物理特性,试验表明添加了粘结剂的进口草炭粘聚能力更强,适宜用作下压式取苗方式的育苗基质;为防止钵苗提前脱落,正四棱台形组合式穴盘的穴孔锥度应选择0.5°。2.综合各种取苗方式的优劣势提出气动下压式取苗方式。设计了一种底板可分离的正四棱台形组合式穴盘。提出气吹式取苗机构和气动柔性下压式取苗机构两种取苗机构。进行气吹取苗试验,发现气吹取苗方式对钵体的损伤过大,最终摒弃气吹取苗方案。提出柔性零件与刚性零件相结合的方法,在梯形顶头上设计柔性避苗布,实现对秧苗茎杆的保护,得到一种对秧苗和基质损伤小、取苗效果好、体积小的气动柔性下压式取苗机构。3.对取苗顶杆进行运动学和动力学分析,得到取苗顶杆的动力学方程,借助Matlab计算出取苗顶杆完成一次取苗动作所需的时间,利用作图法求出取苗顶杆与供苗机构驱动的穴盘的相对运动轨迹。4.在传统的吊杯式栽植机构的基础上提出了一种跑道形吊杯式零速栽植机构。同样采用了平行四杆机构的运动特性保证吊杯在整个工作过程中始终保持竖直姿态,其跑道形的运动轨迹可保证该机构从吊杯插入土壤到吊杯完全张开前的绝对速度始终为零,且吊杯离开钵苗时处于完全打开状态,从而避免了吊杯离开时对钵苗的拨动干扰,保证其较好的直立度。5.设计了与气动柔性下压式取苗机构匹配的供苗装置。结合下压式取苗机构对供苗机构的要求,设计了由两段输送带组成,步进电机驱动的供苗机构。根据取苗机构的特殊要求,输送带上设计了裙边形挡边,倒"T"形隔条,滑靴型、滚轮型压盘装置等。6.设计了气动时序控制系统。对单片机进行编程,用弱电控制强电的原则,通过对继电器、电磁阀等元件的控制实现供苗机构和取苗机构的匹配运行。7.搭建连续取苗试验台并进行连续取苗试验,检验气动下压式取苗方式的可行性,验证取苗机构、供苗机构,气动时序控制系统协同工作的性能。
[Abstract]:Vegetables play an important role in people's dietary structure and are important sources of vitamins and mineral salts needed by human body. Vegetable production is an important part of agricultural output and has become the pillar industry of Chinese agriculture and rural economy. Vegetable transplanting can save the time of farming and improve the yield and quality. The use of automatic transplanter can solve the shortage of labor, high cost and low efficiency in vegetable transplanting. In this paper, a new method of seedling extraction is put forward, and the design and optimization of the core parts of the automatic transplanting machine are carried out. The relevant experiments and studies are carried out in the following aspects: 1. The shape and size of the seedling, the compressive performance of the substrate, the ejection force, the friction coefficient and the crashing resistance were tested and measured to study the relative physical characteristics of the bowl seedling which may affect the seedling extraction effect. The results showed that the imported peat with binder had stronger cohesive ability and was suitable for seedling raising in the way of seedling extraction under pressure, and 0.5 掳. 2. In order to prevent the seedling from falling off early, the hole taper of the compound hole plate with four edges should be selected as 0.5 掳.2. Combined with the advantages and disadvantages of various seedling extraction methods, the pneumatic lower pressure seedling extraction method was put forward. In this paper, a kind of compound hole plate with four prisms is designed, which can be separated from the bottom plate. Two kinds of seedling extraction mechanism, pneumatic flexible and pneumatic pressure mechanism, are put forward. It was found that the damage to the bowl body was too great by the method of air blowing, and the scheme of seedling extraction by air blowing was abandoned. The method of combining flexible parts with rigid parts is put forward. The flexible seedling shedding cloth is designed on the top of trapezoid, which can protect the stem of seedling. The result shows that the damage to seedling and substrate is small, and the effect of seedling extraction is good. Compact pneumatic flexible pressure-extraction mechanism. 3. The kinematics and dynamics analysis of seedling top rod was carried out, and the dynamic equation of seedling top rod was obtained. The time needed to complete one seedling extraction was calculated by Matlab. The relative motion trajectory of the top stem of the seedling and the hole disk driven by the seedling donor mechanism is obtained by using the method of drawing. Based on the traditional hoist-type planting mechanism, a runway-shaped cup-type zero-speed planting mechanism is proposed. The kinematic characteristics of parallel four-bar mechanism are also used to ensure the vertical attitude of the suspension cup throughout the whole working process, and the track of the runway can ensure that the absolute velocity of the mechanism from the cup insertion into the soil to the complete opening of the suspension cup is always zero. When the cup leaves the bowl seedling, it is in a completely open state, thus avoiding the disturbance of the hoisting cup to the bowl seedling, and ensuring its good upright degree of .5. A seedling feeding device matched with pneumatic flexible pressure-taking mechanism was designed. According to the requirement of the seedling feeding mechanism, a seedling feeding mechanism is designed, which is composed of a two-stage conveyor belt and driven by a step motor. According to the special requirements of the seedling collecting mechanism, the conveyor belt is designed with skirt flange, inverted "T" shape partition, slipper type, roller press device and so on. The pneumatic timing control system is designed. The single chip computer is programmed, and the principle of weak electricity control is used to realize the matching operation of seedling feeding mechanism and seedling picking mechanism by controlling relay, solenoid valve and other components. A continuous seedling sampling test bench was built to test the feasibility of pneumatic pressure-extraction method and to verify the cooperative performance of seeding mechanism, seedling feeding mechanism and pneumatic timing control system.
【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S223.9

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