曲柄连杆式桑叶采摘机的关键部件结构设计与优化

发布时间：2019-06-15 09:01

【摘要】：随着我国东桑西移战略的实施,桑农养蚕越来越多,桑叶需求量越来越大,但桑叶采摘自动化程度仍然比较低,国内的桑叶采摘作业基本上还是以手工为主。鉴于此,本文针对我国桑叶采摘机技术落后,主要停留在人工采摘桑叶这一现状,进行了桑园种植情况调研和了解桑农桑叶采摘方式,并在分析国内外桑叶采摘机技术基础上,针对桑叶采摘机采摘过程中桑枝的输送、间歇拨动定位、采摘等环节存在技术问题,对桑叶采摘机间歇拨动定位装置及采摘装置的关键机构进行详细分析,以获得圆柱分度凸轮具体运动参数,最终设计一种连杆式自动桑叶采摘机来代替人工采摘,以降低桑农劳动强度。本文主要从以下几个方面展开研究:(1)到桑园调查研究,了解桑园管理模式、桑树生长情况以及桑农采摘桑叶方式。并根据国内外桑叶采摘机采摘机理、桑叶采摘机的发展趋势以及工作环境分析研究,确定桑叶采摘刀具所行走行程为1200mm,桑树主杆离地面高度为200mm。根据调查可知桑园桑树种植一般垄距为80cm,株距为40cm。用弹簧测力计和小刀片对桑叶叶柄进行简单的切割力学试验,确定桑叶叶柄末鞘和桑树主杆连接处力的大小,试验结果显示叶柄的切割力主要集中在2N-6N范围之间。(2)设计连杆式桑叶采摘机总装结构,对其传动系统以及主要工作部件—行走装置、底座装置、间歇拨动定位装置、桑叶采摘装置以及其他辅助机构进行设计。以增加桑叶采摘装置上曲柄滑块机构的最小传动角为目标,勾型导轨最低点与曲柄转动中心的距离为1400mm,为构成偏心曲柄滑块机构,曲柄长度的取值范围是[450,600],连杆的取值范围是[800,1400],以滑块最大行程不超过勾型导轨最低点和偏心曲柄滑块机构曲柄、连杆需要满足的长度条件为约束;建立优化数学模型;利用Pro/E上的优化模块进行分析,从而获得最佳设计参数:曲柄长度为547mm,连杆长度为1275mm,最终求得最小传动角为39.4°,与最小传动角的理论计算基本吻合,使采摘机构获得最佳的传动性能。根据优化结果对桑叶采摘装置和间歇拨动定位装置的运动时间进行协调匹配研究,确定桑叶采摘机的一个采摘周期为5.7s,其中桑枝拨动时间为1.3s和定位时间为4.4s。(3)对间歇拨动定位装置的关键部件圆柱分度凸轮进行分析研究,结合桑叶采摘装置运动规律和圆柱分度凸轮的结构特点,将圆柱分度凸轮划分为分度期和停歇期,根据计算确定分度期转角为820,停歇期转角为2780。通过分析计算,确定圆柱分度凸轮和分度盘的结构参数,完成间歇拨动定位装置的结构设计。使间歇拨动定位装置与桑叶采摘装置的运动时间协调匹配,保障了物流畅通,使桑叶采摘能够顺利进行。
[Abstract]:With the implementation of the strategy of moving from east to west in China, there are more and more mulberry farmers raising silkworm, and the demand for mulberry leaves is increasing, but the degree of automation of mulberry leaf picking is still relatively low, and the domestic mulberry leaf picking operations are basically manual. In view of this, in view of the backward technology of mulberry leaf picking machine in our country, this paper mainly stays in the present situation of artificial picking mulberry leaf, investigates the planting situation of mulberry garden and understands the picking mode of mulberry leaf, and on the basis of analyzing the technology of mulberry leaf picking machine at home and abroad, aiming at the technical problems of mulberry branch transportation, intermittent plucking positioning and picking in the picking process of mulberry leaf picking machine, The intermittent plucking positioning device of mulberry leaf picking machine and the key mechanism of picking device are analyzed in detail in order to obtain the specific motion parameters of cylindrical dividing cam. Finally, a connecting rod automatic mulberry leaf picking machine is designed to replace manual picking in order to reduce the labor intensity of mulberry farmers. This paper mainly studies from the following aspects: (1) to the mulberry garden investigation and study, to understand the mulberry garden management model, mulberry growth and mulberry farmers pick mulberry leaves. According to the mechanism of mulberry leaf picking at home and abroad, the development trend of mulberry leaf picking machine and the analysis of working environment, it is determined that the walking stroke of mulberry leaf picking tool is 1200 mm, and the height of mulberry main rod from the ground is 200 mm. According to the investigation, the general ridge distance of mulberry planting in mulberry garden is 80 cm, and the plant spacing is 40 cm. The simple cutting mechanics test of mulberry leaf petiole was carried out with spring dynamometer and blade, and the force between the end sheath of mulberry leaf petiole and the main rod of mulberry tree was determined. the test results showed that the cutting force of petiole was mainly concentrated in the range of 2N-6N. (2) the general assembly structure of connecting rod mulberry leaf picking machine was designed, and the transmission system and main working parts, such as walking device, base device and intermittent swinging positioning device, were designed. Mulberry leaf picking device and other auxiliary mechanisms are designed. In order to increase the minimum transmission angle of the crank slider mechanism on the mulberry leaf picking device, the distance between the lowest point of the hook guide rail and the rotation center of the crank is 1400 mm. In order to form the eccentric crank slider mechanism, the value range of the crank length is [450600], and the value range of the connecting rod is [800, 450600]. The maximum stroke of the slider does not exceed the lowest point of the hook guide rail and the crank of the eccentric crank slider mechanism. The optimization mathematical model is established and analyzed by using the optimization module on Pro/E, and the optimum design parameters are obtained: the crank length is 547mm, the connecting rod length is 1275mm, and the minimum transmission angle is 39.4 掳, which is basically consistent with the theoretical calculation of the minimum transmission angle, so that the picking mechanism can obtain the best transmission performance. According to the optimization results, the motion time of mulberry leaf picking device and intermittent plucking positioning device is studied. It is determined that one picking period of mulberry leaf picking machine is 5.7 s, in which the mulberry branch plucking time is 1.3 s and the positioning time is 4.4 s. (3) the cylindrical dividing cam, which is the key component of the intermittent plucking positioning device, is analyzed and studied, combined with the motion law of mulberry leaf picking device and the structural characteristics of cylindrical dividing cam. The cylindrical dividing cam is divided into dividing period and stopping period. According to the calculation, the rotation angle of the dividing period is 820 and the rotation angle of the stopping period is 2780. Through the analysis and calculation, the structural parameters of the cylindrical dividing cam and the dividing plate are determined, and the structural design of the intermittent toggling positioning device is completed. The motion time of the intermittent plucking positioning device and the mulberry leaf picking device is coordinated and matched, which ensures the smooth flow of the logistics and makes the mulberry leaf picking proceed smoothly.
【学位授予单位】：广西科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S225.93

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