【作者】 宗望远；

【导师】 廖庆喜；

【作者基本信息】 华中农业大学 ， 农业机械化工程， 2013， 博士

【摘要】 油菜是中国面积最大的油料作物。针对我国油菜联合收获技术研究中存在的脱粒分离装置结构复杂、性能较低,尤其是损失率、含杂率居高不下的现实问题,研究设计了一种新型油菜脱离系统,将传统割台的割断、输运和脱粒等功能进行集成。利用虚拟样机技术设计集成作业滚筒,并设计制作台架试验装置；建立油菜输运的动力学模型,利用MATLAB软件进行模型的分析与模拟,探求油菜运送机理；利用离散元方法分析油菜在脱粒腔内的受力状态与运动规律,揭示油菜脱粒机理；开展了集成作业滚筒脱粒效果的台架试验。主要研究内容有如下几个方面：(1)开展了油菜茎秆与果荚基础力学特性的测试实验,阐释了油菜茎秆与果荚在剪切和压缩作用下的力学特性。结果表明：茎杆剪切力和压缩力随时间的变化并不明显,靠近最后收获期的油菜茎杆剪切力并不是实验测得的最大值,因而在确定油菜收获时间时可以不将割断功耗作为影响因素。油菜果荚挤压力变化和其生长日期有一定关联,随着成熟度的提高,果荚含水率逐步降低,其生物质结构变得易于发生变形和开裂,这有利于油菜的脱粒作业。(2)开展了不同脱粒方式对收获期油菜果荚脱粒效果的对比分析研究,阐释了不同脱粒方式对油菜果荚的脱粒效果。结果表明：果荚脱净率和脱粒功耗之间呈对数关系,在脱粒功耗较低时,油菜果荚脱净率随脱粒功耗的增加而大幅度提高,但是随着脱粒功耗继续增加,增加速率逐渐变缓并趋于其极限值。同时功耗的增加也易于导致果荚壳的破碎和籽粒的破损,进而增大分离和清选过程的难度和降低收获油菜籽粒的品质,因而不宜为了提高脱净率而一味地增大脱粒功耗；搓擦脱粒油菜果荚脱净率高达99%,而碾压脱粒脱净率小于86%,冲击脱粒脱净率小于66%,在单位脱粒量功耗大于0.5J/g后,相同脱粒功耗下,揉搓脱粒的脱净率高于碾压脱粒和冲击脱粒,油菜联合收割机脱粒装置宜选择冲击脱粒和搓擦脱粒组合的脱粒方式。为此论文选择脱粒钉齿和编织筛网组合、轴流方向自下而上的技术实施油菜联合收获后的脱离。(3)设计了一种新型的组合式油菜脱离系统。在传统收获机割台的割断和输送功能的基础上,在割台滚筒上增设脱粒钉齿和切刀,使得割台滚筒在输送功能的基础上同时具有脱粒和割断功能；取消传统机型中的链耙式输送装置,将纵轴流脱离滚筒的喂入机构直接和割台滚筒的伸缩拨齿机构相接,缩短了物料传送环节,简化了结构。为有效开展该系统的试验研究,分别配套设计并试制了纵轴流脱离试验装置和组合式脱离试验装置。(4)利用高速摄影技术和离散元分析方法,对油菜在伸缩拨齿机构作用下进入到纵轴流脱离系统以及在该系统中运动的过程进行了观察和分析。结果表明：油菜在伸缩拨齿作用下按抛物线轨迹运动到纵轴流脱离系统,并在该脱离系统内作不规则圆周螺旋运动,其轴向运动速度呈现出近似脉动变化特征,受到的作用力主要来自于和脱粒钉齿与顶盖螺旋撞击产生的间歇震荡的冲击力。籽粒在脱离滚筒内的轴向运动速度较快,螺旋轨迹线的螺距较大,秸秆的轴向运动速度慢于籽粒,其螺旋轨迹线的螺距较小。物料在上升时段的速度较低,在下落阶段和遭受撞击后的速度较高。(5)开展了纵轴流脱离滚筒对完熟期油菜的脱离试验。结果表明：脱粒滚筒转速、钉齿间距、脱粒间隙和滚筒轴线倾斜角等因素都影响到筛下籽粒脱出比率。筛下籽粒脱出比率与滚筒转速之间呈现出抛物线关系,转速为771r/min时筛下籽粒脱出比率最高。钉齿间距取为100Omm、225mm、前半段间距200mam与后半段间距为100mm组合三种形式均可得到较高的筛下籽粒脱出比率；脱粒间隙取为25mam和滚筒轴线倾斜角度为250的筛下籽粒脱出比率较高；筛下物由籽粒、颖杂和茎杆等成分组成,筛下脱出各成分沿滚筒轴线呈现出小尺寸脱出物前多后少、大尺寸脱出物前少后多的分布规律,籽粒、杂余等几何尺寸较小的脱出物在滚筒前端脱出量较大后端脱出量较少,几何尺寸较大的茎秆则在滚筒前端的脱出量较小后端脱出量较大。更多还原

【Abstract】 As the main oil crop, rape has the largest plant area in China. Aiming to the problems of the rape combine harvesting technique development with complicated structure and worse performance, especially great loss ratio and low purity, a new threshing and separating system was designed by combining the functions of cutting, conveying and threshing on the traditional header. The integrated roller was designed by virtual prototype technology, and the testing device was manufactured to do the experiment; the dynamic model of conveying on rape was established to analyze on MATLAB software for researching the rape conveying mechanization; The force issue and motion law of rape in threshing cavity were analyzed by discrete element method to reveal the rape threshing mechanization; The threshing effect of the integrated roller were conducted on bench test. So the main researches of my subject listed as below:(1) The basic mechanical characteristic experiments for the rape stalk and capsule were introduced on the sheared and compressed characteristic, the results showed that shear force and compressing force of rape stalk were not significant changing with the time, while the shear force of rape stalk near the harvesting time was not the maximum value in the experiment, so the power consumption of cutting should not be considered as the influence factor on the harvesting time; The compressing force of capsules was related with the time. With the promotion of maturity, the moisture content of capsule decreased, the biomass structure of capsule easily became to deform and crack, and it was beneficial to thresh.(2) The effects on different threshing methods for rape capsule with rubbing, rolling and impact were conducted. The results showed that the threshing rate had a logarithm relation with the power consumption. When the power consumption of threshing was very low, the threshing rate would greatly increase with the power consumption increasing, and then reach the maximum; meanwhile the percentage of broken capsule and seeds would increase with the power consumption increasing, thus the difficulty of separating and cleaning would appear and the quality of seeds on harvesting process would be worse, so it is not reasonable to enlarge power consumption for improving the threshing rate. The results showed that the threshing rate of rubbing was99%, the threshing rate of rolling was lower than86%, the threshing rate of impact was less than66%; and the threshing effect of rubbing was better than the other methods when the power consumption per unit rape seed was more than0.5J/g. It was recommended for rape threshing mechanism that rubbing method combined with impact method. So the technologies of thresh tooth combined with the woven screen and materials flowing up along with the axial direction were used in the threshing and separating system.(3) A new combined threshing system was designed. The thresh teeth and cutting knives were installed in the header roller to make the conventional header roller have new functions of threshing and cutting; the chain rake conveyor in conventional style was abandoned, and the feeding device of longitude axial threshing roller was connected directly back to the telescopic tooth unit of head roller, thus it would shorten the stage of conveying and simplified the structure of threshing system. In order to conduct the experiments, the longitude axial threshing device and combine threshing device were manufactured to test.(4) The process that the materials enter the longitude axial threshing system and move in it was observed and analyzed through the high-speed photography technique and the discrete element analysis method. The results showed that rape was pushed into the threshing system as the parabolic trajectory and take an irregular spiral motion in the threshing system; the axial velocity of rape revealed the approximate pulsating feature, the forces affected on rape came from the intermittent impact between the threshing teeth and the spiral guide plate. The axial speed of rape seed was faster than rape stalk, and the screw pitch of spiral trajectory was longer than rape stalk’s as well. The velocities of rape seed and rape stalk were higher in the periods of falling down and impacting than the period of rising up.(5)The longitude axial threshing roller was used to conduct the threshing test of ripe rape. Single factor experimental results showed that all factors such as roller speed, spike tooth space, roller screen gap and threshing drum axis tilt angle affect the grain prolapsed ratio. The grain prolapsed ratios has a parabolic relationship with the roller speed, in whi ch the ratio reach the maximum value when the roller speed is771rpm. It has a high valu e when the spike tooth space is100mm,225mm or200mm for front half of it and100mm for back half. It also has a good performance when roller screen gap is25mm or the thres hing drum axis tilt angle is25degree. The distribution of all of the ingredients prolapsed have a regularity that most of the small size extractions such as rapeseeds are in front of the area along the axis of roller while most of the large size extractions such as stem are i n the back area.更多还原