本文關(guān)鍵詞： 排種器 精量排種 吸孔結(jié)構(gòu) 流場仿真 試驗研究　出處：《浙江理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來,隨著人民生活水平逐步提高,對蔬菜需求量增加,中國已逐漸成為世界上最大的蔬菜生產(chǎn)國和消費(fèi)國。蔬菜生產(chǎn)具有季節(jié)性,而溫室技術(shù)的應(yīng)用改變了蔬菜種植受季節(jié)限制的特點(diǎn),但是,溫室種植的蔬菜大多采用育苗移栽方式,而蔬菜種子由于其粒徑小,形狀不規(guī)則,目前仍舊以人工或半機(jī)械化方式育苗為主,工作效率低。因此,開發(fā)適合蔬菜種子外形特點(diǎn)的排種裝置,對蔬菜種植業(yè)全程機(jī)械化推廣具有重要意義。本文針對蔬菜種子粒徑小,形狀不規(guī)則等特點(diǎn),提出一種氣力滾筒式異形種子精量排種器,并以芹菜種子良峰玉芹為試驗對象,進(jìn)行試驗研究。本文主要研究內(nèi)容:(1)基于蔬菜種子異形的物理特性,提出了一種氣力滾筒式異形種子精量排種器。完成排種器結(jié)構(gòu)參數(shù)設(shè)計,包括吸孔結(jié)構(gòu)設(shè)計、滾筒內(nèi)腔結(jié)構(gòu)設(shè)計、滾筒直徑設(shè)計、滾筒軸向及周向吸孔間隔設(shè)計。(2)建立了排種過程種子的動力學(xué)模型,獲得吸種階段排種滾筒直徑、吸孔直徑、滾筒轉(zhuǎn)速等因素對最小負(fù)壓區(qū)壓力的影響規(guī)律,攜種階段最小吸附力的變化規(guī)律,進(jìn)行投種階段滾筒轉(zhuǎn)速、正壓區(qū)壓力值對種子水平位移的影響研究。(3)進(jìn)行氣力滾筒式異形種子精量排種器氣流場仿真分析,獲得正、負(fù)壓區(qū)流場分布規(guī)律,得到正、負(fù)壓區(qū)的吸孔端面壓力與正、負(fù)壓區(qū)的入口正壓值、出口負(fù)壓值呈近似線性關(guān)系。進(jìn)行吸孔參數(shù)對排種器正、負(fù)壓區(qū)流場分布的影響研究,獲得最佳吸孔結(jié)構(gòu)參數(shù)組合。(4)對氣力滾筒式異形種子精量排種器排種過程進(jìn)行耦合分析,研究排種器正壓區(qū)入口壓力值、滾筒轉(zhuǎn)速對種子運(yùn)動狀態(tài)的影響規(guī)律,得到投種過程種子水平方向速度降與正壓口壓力呈線性關(guān)系。(5)研制氣力滾筒式異形種子精量排種器,開展排種性能測試。分別以吸孔結(jié)構(gòu)參數(shù)、排種器運(yùn)行參數(shù)為試驗對象進(jìn)行單因素試驗研究,再進(jìn)行正交試驗研究,試驗結(jié)果表明:排種器合格率、重播率、空穴率、單粒率受吸孔直徑、吸孔末端直徑、滾筒轉(zhuǎn)速以及正、負(fù)壓口壓力值影響均較為顯著。當(dāng)吸孔直徑為0.7mm,吸孔末端直徑為2mm,吸孔過渡層直徑為2mm,轉(zhuǎn)速為12r/min,正壓口壓力值為1500Pa,負(fù)壓口壓力值為-4000Pa時,排種器工作狀態(tài)最佳,排種合格率達(dá)到71.78%,空穴率為16.82%。
[Abstract]:In recent years, with the gradual improvement of people's living standards and the increasing demand for vegetables, China has gradually become the world's largest vegetable producer and consumer. Vegetable production is seasonal. The application of greenhouse technology has changed the seasonal limitation of vegetable planting. However, most of the vegetables grown in greenhouse are planted by transplanting seedlings, and the seeds of vegetables are irregular because of their small diameter. At present, it is still mainly artificial or semi-mechanized, and its working efficiency is low. Therefore, a seed metering device suitable for the appearance characteristics of vegetable seeds is developed. Aiming at the characteristics of small grain size and irregular shape of vegetable seeds, a pneumatic roller type special-shaped seed metering device was put forward, and the celery seed Liangfeng Jade celery was taken as the experimental object. In this paper, based on the physical characteristics of vegetable seed specialities, a pneumatic roller type seed metering device with special-shaped seed is proposed. The structure parameters of the metering device are designed, including the design of sucking hole structure, the main content of this paper is as follows: (1) based on the physical characteristics of the abnormal shape of vegetable seed, a pneumatic roller type seed metering device is proposed. The design of inner cavity, diameter of drum, interval between axial and circumferential suction holes of roller are designed. The dynamic model of seed seeding process is established, and the diameter of seeding drum and suction hole is obtained in the stage of sucking seed. The influence of cylinder speed and other factors on the pressure in the minimum negative pressure region and the variation rule of the minimum adsorption force in the seed carrying stage, and the rotating speed of the roller in the feeding stage, Study on the effect of pressure value in barotropic region on horizontal displacement of seed. (3) Simulation analysis of airflow field in pneumatic cylinder type special-shaped seed metering device is carried out, and the distribution law of flow field in positive and negative pressure zone is obtained, and the pressure and positive face of suction hole in positive and negative pressure region are obtained. The inlet positive pressure and outlet negative pressure of negative pressure region are approximately linear. The influence of suction hole parameters on the flow field distribution in the positive and negative pressure region of the metering device is studied. The optimum structure parameter combination of suction hole is obtained. The coupling analysis is carried out on the seeding process of the pneumatic cylinder type special-shaped seed metering device. The influence of the inlet pressure in the positive pressure zone of the metering device and the rotational speed of the roller on the seed motion is studied. The linear relationship between the horizontal velocity drop of seed and the pressure of barotropic orifice was obtained. 5) the pneumatic roller type seed metering device was developed, and the metering performance test was carried out. The parameters of suction hole structure were used respectively. The operation parameters of seed metering device were studied by single factor test and orthogonal test. The results showed that the qualified rate, resowing rate, hole rate, single grain rate and terminal diameter of suction hole were obtained. When the diameter of suction hole is 0.7 mm, the end diameter of suction hole is 2 mm, the diameter of transition layer of suction hole is 2 mm, the rotational speed is 12 r / min, the pressure value of positive pressure port is 1500 Paa, and the pressure of negative pressure port is -4 000 Pa. The seed metering device has the best working condition, the qualified rate of seed metering is 71.78 and the hole rate is 16.82.
【學(xué)位授予單位】：浙江理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S223.2

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本文編號：1533853