气吸圆盘式微型薯排种器的设计与试验

发布时间：2018-05-06 01:00

本文选题：微型薯 + 气吸式排种器　；参考：《昆明理工大学》2017年硕士论文

【摘要】：马铃薯是继水稻、小麦和玉米之后的世界第四大粮食作物。在当今生态环境不断恶化、耕地面积逐年减小的情况下,大力促进马铃薯主粮化,是保证我国粮食安全的重要发展战略。我国已成为世界马铃薯生产第一大国,但却不是马铃薯产业强国,原因之一是我国马铃薯主要以切块薯为种薯,易产生病毒感染;二是我国马铃薯生产机械化水平低。随着微型薯栽培脱毒技术的提高,马铃薯种薯易受到病毒感染的问题得到有效改善,微型薯的需求量也大大提高,但目前我国对于微型薯的种植仍然大多采用人工作业的方式,人工种植微型薯不仅需要大量的人力成本,而且作物的行距、株距和深浅度不一致,从而影响马铃薯产量。本课题针对微型薯等大粒种子不易充种的问题,设计了一种可振动供种的气吸圆盘式微型薯排种器,通过理论计算与数值模拟,确定了其主要结构参数,利用离散元法模拟研究振动对于排种器充种性能的影响,为寻求最佳工作参数组合,采用三因素四水平正交试验方法,对排种器进行排种性能试验。具体开展的研究内容如下:(1)对微型薯的物理机械特性进行了测量试验:平均长、宽、厚分别为24.1mm、20.5mm 和 18.2mm;含水率为 82.09%;平均粒重 5.57g;密度 1059.89km/m3;与304不锈钢、有机玻璃、Q234钢以及橡胶的静滑动摩擦角分别为24.5°、29°、28.5°和20°;休止角32.35°。(2)设计了一种可振动供种的气吸圆盘式微型薯排种器,介绍了其工作原理,通过理论计算和数值模拟确定了相关结构参数:排种盘直径380mm;吸孔直径13mm;吸孔深度6mm;吸孔数量8个。(3)利用FLUENT软件模拟排种器气室内部流场,为风机接口的选取提供参考;通过理论计算和ADAMS软件对振动参数进行选取。以作业速度、吸种负压和振动频率为试验因素进行排种性能正交试验,最终确定最优工作参数组合为作业速度2.4km/h,振动频率6.5Hz,吸种负压6kPa。在此条件下该排种器的排种合格指数为94.2,漏播指数为1.7,重播指数为4.1,满足国家精量播种的技术要求。(4)基于离散元法,利用EDEM软件进行振动频率和振动幅度对种群扰动影响的仿真分析,得出振动过程中种群运动状态在不同振动参数下的变化趋势,并进行台架验证试验。采用三因素五水平二次旋转正交组合试验方法,寻求各参数的最佳区间组合,在种层高度为70mm,振动频率为6.5～7.0Hz,振动幅度为20～21mm时,可获得合格指数大于95,漏播指数小于2.5,重播指数小于2.5,进行了验证试验,试验结果与优化结果基本相符。(5)验证了所设计振动供种机构对微型薯造成的破损情况。随着振动频率的增加,微型薯破损率呈上升趋势,但未超过1%,因此,振动供种机构对微型薯的损伤不大。所得结论可以为微型薯气吸式精密播种机械研究的继续开展提供理论基础和参数依据。
[Abstract]:Potatoes are the fourth largest food crop in the world after rice, wheat and corn. With the deterioration of ecological environment and the decrease of cultivated land area, it is an important development strategy to ensure the food security of our country. China has become the largest potato production country in the world, but it is not a powerful potato industry. One of the reasons is that the potato in our country mainly takes cut potato as seed potato, it is easy to produce virus infection, and the mechanization level of potato production in our country is low. With the improvement of virus-free technology of microtuber cultivation, the problem that potato seed potato is susceptible to virus infection has been effectively improved, and the demand for microtuber has been greatly increased. However, at present, the cultivation of microtuber in China is still mostly done by artificial operation. Artificial cultivation of microtubers not only requires a large amount of labor costs, but also the row spacing, plant spacing and depth of the crop are not consistent, thus affecting the yield of potato. Aiming at the difficulty of filling seeds with large seeds such as micro-tubers, a kind of air-sucking disc micro-tuber metering device is designed, which can be used to supply seeds by vibration. The main structural parameters are determined by theoretical calculation and numerical simulation. The effect of vibration on seeding performance of metering device was simulated by discrete element method. In order to find the best combination of working parameters, three factors and four levels orthogonal test method was used to test the seeding performance of metering device. The physical and mechanical properties of microtubers were measured as follows: the average length, width and thickness were 24.1mm 20.5 mm and 18.2mm; the moisture content was 82.09; the average grain weight was 5.57g; the density was 1059.89km / m3; and 304 stainless steel, The static sliding friction angles of organic glass steel Q234 and rubber are 24.5 掳/ 29 掳/ 28.5 掳and 20 掳, respectively, and the angle of repose is 32.35 掳. Through theoretical calculation and numerical simulation, the relevant structural parameters are determined: the diameter of seeding disk is 380 mm, the diameter of suction hole is 13 mm, the depth of suction hole is 6 mm, the number of suction holes is 8 mm, and the flow field in the gas chamber of seeding device is simulated by FLUENT software, which provides a reference for the selection of fan interface. The vibration parameters are selected by theoretical calculation and ADAMS software. The orthogonal experiment of seeding performance was carried out with the operating speed, suction negative pressure and vibration frequency as the test factors. Finally, the optimal working parameters were determined as working speed 2.4 km / h, vibration frequency 6.5 Hz and suction negative pressure 6 KPA. Under this condition, the seed quality index of the metering device is 94.2, the missing seeding index is 1.7, and the replanting index is 4.1, which meets the technical requirements of national precision seeding. The effect of vibration frequency and vibration amplitude on population disturbance is simulated by using EDEM software. The variation trend of population motion under different vibration parameters is obtained, and the experiment is carried out on a bench. By using the method of three factors and five levels quadratic rotation orthogonal combination test, the optimum interval combination of each parameter is obtained. When the height of seed layer is 70mm, the vibration frequency is 6.5Hz7.0Hz and the amplitude of vibration is 20~21mm, The qualification index is greater than 95, the missing seeding index is less than 2.5, and the replanting index is less than 2.5. The test results are in good agreement with the optimized results. With the increase of vibration frequency, the damage rate of microtuber increased, but it was not more than 1. Therefore, the damage of vibratory seed donor to microtuber was not obvious. The conclusion can provide theoretical basis and parameter basis for the research of micro tuber suction precision seeding machine.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S223.2

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