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黑龙江八一农垦大学本科毕业设计I摘要针对长期以来精密播种机的研制存在生产周期长、成本高，而且当产品制出后，经常会 出现部件、零部件之间相互干涉而无法装配等缺点，介绍了应用 UG软件进行精密播种机单 体虚拟制造和运动仿真的过程。 首先对建立的精密播种机单体零件三维模型进行约束和连接 装配，形成精密播种机单体整机装配，然后进行运动仿真，展示在虚拟环境下的运动特性。 最 后对仿真结果进行处理，测试精密播种机单体的运动性能和检测干涉情况，从而对错误进行修 改。 结果表明：该方法提高了精密播种机设计的准确性和效率，代替了物理样机的制造和试 验，大大降低了成本。关键词：农业工程； 精密播种机单体； 虚拟制造； 运动仿真黑龙江八一农垦大学本科毕业设计IIAbstractFacing the 1ong-standing prob1ems existing in the deve1opment of the precision p1anter such as the pro1onged production period, the high production cost and the dificu1ty in the fina1 asemb1y because of the interference betwen the interacted parts, a proces of the virtua1 manufacturing and motion simu1ation of the precision p1anter unit was introduced app1ying the ProIEngineer software.The fina1 asemb1y of the p1anter unit was formed by restricting and connecting its parts 3-D mode1s. Its motion simu1ation was performed to demonstrate the movement characteristics in the virtua1environment.The simu1ation resu1ts were procesed to check the movement characteristics of the p1anter and to corect the posib1e interferences.The resu1ts showed that the proposed proces improves the acuracy and eficiency of the precision p1anter design and deduces the deve1opment cost by using the virtua1 space instead of the physica1 space.Keywords: Agricu1tura1engineering; Precision p1anterunit; Virtua1manufacturing; Motion simu1ation;黑龙江八一农垦大学本科毕业设计III目录摘要.IAbstract.II目录.III前言.V1 我国精密播种机发展现状 .11.1 精密播种机的发展前景.11.2 新技术的应用不断普及.32 运动仿真过程 .43 装配连接 .64 运动仿真预设置.84.1 新建运动仿真方案.84.2 参数设置 .84.3 创建连杆 .84.4 创建运动副 .85 多功能播种机总体设计 .95.1 精播机系统方案设计确定.95.2 农业机械的一般设计要求.105.3 总体参数.10 6 机架设计 .14 6.1 机架设计计算的准则.14黑龙江八一农垦大学本科毕业设计IV6.2 机架设计的一般要求.146.3 精播机机架结构设计方案.157 播种系统设计 .167.1 排种器的选型及其材料的确定.167.2 结构设计.178 开沟器 .248.1 开沟器.248.2 开沟器比较分析及本机开沟器设计.249 覆土、镇压装置 .269.1 覆土器.269.2 镇压轮.269.3 轴承校核.2710 常见故障与排除.28结论.29参考文献.30致谢.31附录.32黑龙江八一农垦大学本科毕业设计V前言精密播种机这类机械产品的设计通常采用二 维几何绘图,产品制造出来后经常会出现一些设 计失误,如零部件无法安装以及运行时发生干涉 等。 采用三维 CAD 设计产品,不是一个单纯绘图 的过程,而是一个虚拟制造的过程。 设计出来的 产品是与实物完全相同的数字产品,零部件之间 的间隙和干涉一目了然,可以把错误消灭在设计 阶段。 对于运动机构的设计,无论是于工绘图设 计还是二维 CAD 的计算机辅助设计,都没有办法 处理,简单的机构还可以模拟,稍微复杂一点的运 动机构就束于无策了。 应用三维设计软件来处理 机构的运动,可以使立体的数字产品在计算机中 运动,模拟真实机械的理论运动过程。 不但能测 试机构是否能运动,还可以检查机构运动时是否 会产生干涉,计算出机构上某个点的运动轨迹,将 机构运动记录下来,产生动态的图片,从而实现机 械产品的虚拟制造和运动仿真。 在国外,虚拟 样机技术已在工业产品的研制上得到应用,取得 了显著的效果。 目前国内将三维 CAD 技术 应用在播种机械方面的研究大多是对零部件 和某一机构进行的三维参数化设计和运动仿真, 而对于精密播种机单体整机进行虚拟制造和运动 仿真方面还未见报道。黑龙江八一农垦大学本科毕业设计VI黑龙江八一农垦大学本科毕业设计- 1 -1 我国精密播种机发展现状我国从 80 年代末便开始研制精密播种机械。由于种子质量、整地条件、机械制造水平及机器价格等因素制约，我国 80 年代主要是推广半精量播种。为适应农村生产责任制的要求，大量推广了小型单体播种机。90 年代以来，我国逐步推广精密播种机，有 10 多个企业生产了 20 多种型号的精密播种机。精密播种机以作物种类分为玉米及大豆精密播种机、谷物（小麦）精密播种机、甜菜精密播种机；以配套动力分为小型（5.813.2kw） 、中型（16.236.8kw）和大型播种机（40.4kw 以上）精密播种机；以排种器形式分为机械式和气力式两大类精密播种机；机械式中又可分为垂直圆盘式、垂直窝眼式、锥盘式、纹盘式、水平圆盘式、带夹式等形式精密播种机。1.1 精密播种机的发展前景1.1.1 单粒精密播种机迅速发展在国外，中耕作物如甜菜、玉米、棉花和某些蔬菜、豆类的播种都已大量采用精密播种，主要采用机械式和气力式两种精密播种机。由于气力式播种机对种子尺寸要求不严，不需精选分级，容易达到单粒精播，而且通用性较好，又能适合较高速播种，因此使用气力式播种机越来越多。 为了达到单粒精播，提高株距均匀性，大多采用可精调的刮种器，将多余的种子清除掉；为了降低投种高度，减小种子下抛速度与前进速度之间的相对速差，而设置导种轮或导种管。但是，精密播种受高速作业的影响很大。现有的精密播种机试验结果表明，一般作业速度在 48 kmh 时，其株距合格率达 80以上；而作业速度提高到 1112 kmh 时，株距合格率下降到 60以下。可见高速精密播种机还有待进一步发展、完善。1.1.2 播种机的通用性和适应性不断提高 大多数精密播种机都可以播多种作物，通过更换不同孔径的排种盘(轮)或排种滚筒，使排种器能适应多种作物种子的播种要求。改变型孔大小或增加成黑龙江八一农垦大学本科毕业设计- 2 -穴机构，使之能达到穴播的要求；改变排种器工作转速以达到不同株距的要求。所有这些均提高了播种机的通用性。为了适应不同地区、不同土壤、不同整地条件的要求，大多数播种机上配有多种类型的开沟器(双圆盘式、滑刀式等)和镇压轮(橡胶轮、钢板冲压轮、铸铁轮、宽轮、窄轮等)，供选用。同一型号的精密播种机又成系列，有多种行距和行数的变型。如美国 CYCLO 气压式播种机有牵引式和悬挂式，有 4、6、8、12、16 行等共 16 种机型，可为多种功率的拖拉机配套。1.1.3 精密播种机向高速宽幅发展 为了在最适宦的农业技术条件下、用最短的时间做到适时播种，以及随着拖拉机功率不断增大，为了充分利用其功率，因此要求提高播种机作业的生产率。 影响提高播种机组生产率的因素很多。除了提高机组的工作可靠性、减少故障、简化操作以减少辅助作业时间、提高纯工作时间的利用率外，提高生产率的最主要途径是增大播种机的工作幅宽和提高作业速度。增大播种机工作幅宽虽能直接有效地提高生产率，但加大工作幅宽使机体庞大，消耗金属多，成本高。同时，庞大的机体将受到田块大小、地头转弯以及道路运输的限制，使用不方便。因此，国外很重视提高作业速度的研究。 70 年代，中耕作物播种机作业速度一般从 46kmh 提高到810kmh。如西德 Aermoat型气力式播种机、法国 Pneumasem 气吸式播种机和美国 7000 型指夹式播种机的作业速度为 810 kmh，作业质量仍能符合要求。但是，播种机高速作业带来一些问题，如排种性能下降，开沟深度变浅，种子在沟里弹跳、滚动加剧，以及驾驶条件恶化等等。因此，目前作业速度不能太高。中耕作物播种机的工作幅宽，一般单机都由 34 m 增大到 56 m 有的工作幅宽更大，如美国 CYCLO 气压式播种机系列中的 16 行播种机，其幅宽达11.68 m。加大幅宽使播种机结构庞大笨重，使悬挂式播种机组纵向稳定性变坏，还受到地块大小、道路运输的限制。黑龙江八一农垦大学本科毕业设计- 3 -1.1.4 广泛采用联合作业 播种同时进行联合作业的方式发展很快，形式也比较多，主要有两种：一是在大多数中耕作物精密播种机上都配置排肥器、施肥开沟器以及施撒农药和除莠剂的装置。如西德、法国和美国的几种精密播种机都可以在播种同时施化肥、撒农药和除莠剂。二是播前整地和播种联合作业，如旋耕播种机、犁播机以及有的在开沟器前方加波形圆盘或锄铲进行灭茬播种或少耕法播种，以减少耕作次数，提高生产率，降低作业成本，还可以减少土壤风蚀和起到保墒的作用。1.2 新技术的应用不断普及 为了提高播种机作业性能和工作可靠性，简化操作、减轻劳动强度、减少辅助作业时间、提高生产率，播种机上越来越多地采用新技术。如用液压油缸来升降和调节开沟器、划行器、折叠机架；采用液压马达驱动风机或装肥搅龙；采用信号装置、电子监视装置或监控装置来及时报警故障的发生，显示播量或自控凋节排种量大小；开沟器装备一次润滑的滚动轴承；行走轮采用无内胎充气轮；快速挂接装置；宽幅播种机加装横向运输轮等。 在工艺材料方面，播种机上采用塑料或尼龙的零件更多了，如排种盘、排肥盘、轴套、输种管等；采用铝金压铸排种轮、排种器体壳，提高了零件精度，减轻了重量；播种机机架和各种杆件采用薄钢板冷压成异形断面以代替扁钢、角钢和槽钢，增加了刚度和强度，又减轻了重量。黑龙江八一农垦大学本科毕业设计- 4 -2 运动仿真过程精密播种机单体由仿形机构、机架、开沟器、 排种器、地轮及传动系统、覆土机构组成。 其工作过程是地轮转动, 带动排种盘排 种,同时,开沟器在仿形机构控制下在田间地表开 出播种所需的深沟,种子落入沟内,由覆土机构完 成覆土。 可以看出,精密播种机的工作是由仿形、 开沟、施肥、播种、覆土、镇压等多种工作部件完成 的复杂动态过程,其田间作业指标要求高,设计难 度大,试制及试验的费用相当昂贵。对精密播种机单体进行虚拟制造和运动仿真 的步骤包括零件三维设计、机构装配连接、运动仿 真、运动结果处理和分析等,其工作流程见图 图 2-1 播种机单体简单结构图图 2-2 工作流程图零件设计是三维设计的基础,用软件 的建 立零件 既快 捷又准 确, 通过 拉伸 （ Extrude)、 旋 转 （ Revo1ve)、 扫掠 （ Swep)、 混 成（ B1end) 、抽壳（ She1) 等方法可生成零件实体,并 建立合适的约束条件和特征间父子关黑龙江八一农垦大学本科毕业设计- 5 -系,在设计 过程中可从不同角度观察零件,以便对错误进行 修改。 如排种盘的三维设计过程为：旋转生成基本实体拉伸切除形成中心轴孔建立孔特征数组复制孔特征,完成设计。根据精密播种机单体零件的不同结构特点, 采用不同的设计方法依次对所有零件进行设计, 并建立精密播种机零件库。 可通过模型树（ Mode1Tre) 了解 零件的设计过程, 灵活 地对 其 进 行 修 改。图为精密播种机单体部分零件的三维图图 2-3 部分零件三维图黑龙江八一农垦大学本科毕业设计- 6 -3 装配连接零件设计完成后,就可以利用 UG 软件的模块进行装配连接,UG 软件提供的 零件装配方式有放置和连接两种类型,放置类型 包括匹配（ Mate)、对齐（ A1ign) 、插入（ Insert)、坐 标系（ Cord Sys)、相切（ Tangent)、线上的点（ Pnt on Line)、 曲面上的点 （ Pnton Srf)、 曲面边（EdgeonSrf)以及自动（Automatic)等约束类型。连接类 型 包 括固定 （ Rigid) 、 销钉 （ Pin) 、 滑块 （S1ide)、圆柱 （ Cy1inder)、 平面 （ P1anar) 等方 式。根据精密播种机单体各部件的实际装配关系和部 件的运动功能选择相应的放置类型和连接类型, 能够使装配件实现运动功能,如开沟器柄与仿形机构后支座之间、仿形机构后支座与机架之间、种 箱与机架之间、轴承座与机架之间、排种器壳与机 架之间采用匹配、对齐等约束类型进行放置装配,而仿形机构前后支座与连杆之间、轴与轴承之间、 覆土机构与机架之间等处采用连接装配,先用销钉连接,再用一个轴对齐和一个平面匹配来限制 连接元件沿轴线的平移,装配后连接元件可以绕着元件转动但不能相对于附着元件移动。图 3-1 装配图运动仿真过程为了减少运动副数量，将各个部件之间的运动关系表示清楚，提高机构运动分析的效率。在对花生播种机进行运动仿真之前，首先要根据运动副对花生播种机结构进行简化，建立运动仿真模型。本文运动仿真的目的在于根据运动仿真的结果来研究开沟器的运动轨迹、分析仿形机构设计的合理性黑龙江八一农垦大学本科毕业设计- 7 -及影响仿形误差的因素，并以此为原则，去掉与运动仿真过程无关的部件，进行模型简化。将刚性连接在将悬挂装置简化为一个连杆，去掉起垄装置、排种装置、施肥装置、喷药装置和覆膜装置，简化后的运动仿真模型中只包含拖拉机模型、仿形机构、播种机机架、施肥铲、双圆盘开沟器和限深轮等部件。由于在运动仿真过程中不考虑土壤阻力及土壤的松软性，所以为了提高机构运动仿真分析的效率，在运动仿真模型中将仿形机构上的压力弹簧去掉。黑龙江八一农垦大学本科毕业设计- 8 -4 运动仿真预设置4.1 新建运动仿真方案在 UG 的应用中，选择“开始运动仿真”命令，进入运动仿真分析模块。在运动仿真导航器中新建一个运动仿真模型，在环境对话框中接受默认的“动态”分析。4.2 参数设置选择“首选项运动”命令，弹出运动仿真预设置对话框，选择重力常数为默认值，证角度单位为度。4.3 创建连杆本模型创建了 11 个连杆，标号为 L001 L011。其中，L001 是驱动连杆;L002 为拖拉机; L003 是悬挂架及仿形机构前拉杆; L004 是仿形机构上拉杆; L005 是仿形机构下拉杆; L006 包括仿形机构后拉杆、播种机机架、限深轮、施肥铲和双圆盘开沟器; L007 L009 为施肥铲位置上的辅助连杆; L010 和 L011 为双圆开沟器位置上的辅助连杆。4.4 创建运动副选择“解算方案”命令，设定解算方案类型为“常规驱动” ，分析类型为“运动学/动力学” ，时间为 200s，步数为 300 步。在“解算方案”对话框中，单击“确定”按钮进行解算。解算完成后， “动画控制”对话框自动弹出，单击“动画控制”对话框中的“播放”按钮，通过运动仿真动画来表现花生播种机的运动过程，观察仿形机构和开沟器在上下坡过程中的运动状态，如图 5 所示。运动仿真的结果以图表和电子表格的形式绘出，选择“生成图表”命令，生成运动副 J015 J017 和 J018 J020 的 Y 方向的位移曲线与位移曲线数据点电子表格黑龙江八一农垦大学本科毕业设计- 9 -5 多功能播种机总体设计5.1 精播机系统方案设计确定5.1.1 主要技术参数：1)配套动力：1220 马力四轮拖拉机 2)机具质量：350kg（含水箱） 3)作业行数：两行 4)行距：450550mm （可调） 5)穴距：260-330mm（可调） 6)穴粒数：13 粒 7)播深：4060mm 8)铺膜宽度：6001000（mm） 9)水箱容积：300 升/只 10)施肥箱容积：16 升/只 11)作业速度：23km/h 12)作业生产率：1.5-3 亩/小时 13)播水量根据农艺要求自行控制5.1.2 机具构造该机构主要由机架,主轴总成,刮土板,施肥机构,水箱,植保机构,开沟器,穴灌水机构,镇压机构,铺膜机构及间隔填土压膜机构等组成，其结构图如下所示5.1.3 主要经济指标1)种子破损率90% 3)漏播率95% 5)地膜漏覆土程度e,X=0.56,Y=1.73 （9-1）查表得：Pr=XFr+YFa=9052N轴承 6203 的 Cr=9580N,故选取轴承合适。(2）校核轴承的额定静载荷 Por=4250NCor=4780N （9-1314152）所以轴承 6203 满足要求。10 常见故障与排除1)播种不均匀 若因作业速度变化大，应使作业速度保持均匀；若因刮种舌严重磨损，应更换刮种舌；若困外槽轮卡箍松动，使工作长度变化，应调整外槽轮工作长度，固定好卡箍。黑龙江八一农垦大学本科毕业设计- 27 -2)排种器不排种 种子箱内种子不足时，应添加种子；传动机构不工作，应检修调整传动机构；驱动轮不转动，应排除驱动轮故障；排种轮卡箱、键销松脱时，应重新紧固排种轮；输种管或下种口堵塞，应及时排除堵塞物。 ，3)种子破碎率高 作业速度快，使传动速度过高，易使种子破碎率高，应降低作业速度，保持匀速前进；护种装置损坏，应更换护种装置；刮种舌离排种轮太近时，应调整刮种舌与排种轮的间距。4)播种深度不够 主要因开沟器拉杆变形，入土角度小，使开沟器弹簧压力不足所致。应矫直开沟器拉杆，增大入土角，并调紧弹簧，增加开沟器压力。5)开沟嚣堵塞 播种机落地过猛，开沟器堵土时，应停机清理开沟器的堵土；作业时禁止开沟器入土后倒车。6)覆土不严 覆土板角度不当，应调整覆土板角度；弹簧压力不足，应调紧弹簧。 结论本文利用 UG 软件的运动仿真模块，在对播种机结构进行简化的基础上，建立运动仿真模型，对播种机机构进行运动仿真分析，研究施肥铲和双圆盘开沟器的运动情况。通过播种机的运动仿真动画，可以直观、生动地观察花生播黑龙江八一农垦大学本科毕业设计- 28 -种机在上坡和下坡过程中的运动规律，得到施肥铲和双圆盘开沟器运动轨迹曲线、施肥和播种深度曲线。对运动仿真曲线的研究有利于更好地调整仿形机构设计参数，从而减小仿形误差，保证仿形机构在实际应用中达到最佳仿形效果。参考文献1 董刚等.机械设计M. 北京机械工业出版社，19982 龚桂义.机械设计课程设计指导书M. 高等教育出版社, 1990 3 孙桓,陈作模.机械原理M.高等教育出版社, 2000黑龙江八一农垦大学本科毕业设计- 29 -4 赵明生.机械工程手册专用机械卷(一)M. 北京机械工业出版社,19955 沈鸿.机械工程手册机械产品(一)P. 北京机械工业出版社,19826 吴字泽.机械设计师手册(上、下册)J. 北京机械工业出版社社,20027 汤百智,崔振勇.机械制图M. 北京机械工业出版社,2000 8 龚桂义.机械设计课程设计图册M. 高等教育出版社, 1987 9 吴字泽.机械零件设计手册P. 北京机械工业出版社, 200410 成大先.机械设计手册(1-5 卷)J. 北京机械工业出版社,200211 陆玉,何在册,佟延伟.机械设计课程设计M. 北京机械工业出版社,199812 陈隆德,赵福令.互换性与测量技术基础P. 大连理工大学出版社, 199713 王德奎.农业机械设计手册S. 中国工业出版社，197014 宋正德.农业机械P. 北京人民出版社，197815 何天华.农业机械构造P. 中国工业出版社，196116 吴正龙.农业机械基础S. 人民教育出版社，197817 李正.农业机械学P. 中国农业机械出版社，198018 余俊.机械设计R. 北京高等教育出版社， 198619 Rajput R K. Elements of Mechanical EngineeringJ. Katson Publ. House.1985 20 Orlov P.Fundamentals of Machine DesignR. Moscow: Mir Pub. 1987致谢本次设计的主要目的和主导思想是对播种机的结构进行仿真。在设计中进一步加深了对机械设计的实践能力，也对在大学四年里学到的其他相关课程进行了黑龙江八一农垦大学本科毕业设计- 30 -全面的复习和运用。尤其在综合分析和解决问题，独立工作能力方面得到了很大的锻炼。锻炼了我们的查阅资料的能力培养了我们的协同工作的能力，但也暴露了我们的不足比如基础不牢靠缺乏经济观念等。由于时间的关系和能力的限制，在设计中难免存在错误和不足。恳请老师的批评和指正。在本次的设计中，得到了机械系全体老师的大力帮助和指导让我受益匪浅。使我得以顺利的完成设计，再次表示衷心的感谢。附录DesignDesign ofof sawingsawing anti-blockinganti-blocking mechanismmechanism forfor黑龙江八一农垦大学本科毕业设计- 31 -no-tillageno-tillage planterplanter andand itsits cuttingcutting mechanismmechanismLiao Qingxi1,Gao Huanwen2,Shu Caixia1AbstractAbstract: Based on blocking issues of no-tillage planter for dry-land farming in two-crop-a-year region in North of China and shortcomings of anti-blocking mechanism developed, such as higher rotation speed (above 1500 r/min) and bigger power consumption (width power consumption per unit up to 1641.74 kW/m, including traction power), a new sawing anti-blocking mechanism was developed and its cutting mechanism was investigated in this paper. Meanwhile stress distribution of the saw-tooth blade calculated by the ANSYS finity element software showed that the saw-tooth blade would be feasible to cut corn straws. Experimental results in the soil bin showed that: 1)The sawing anti-blocking mechanism with two cutting modes of sustaining and no-sustaining cut could realize an integrated function of cutting and directly throwing by reverse rotation, namely, it could throw straws directly to the rear of the opener by former angle of saw-tooth and thrower; 2)The cutting rate of straws would increase along with the rising of straw moisture and rotation speed, and higher moisture of straws would be of benefit to improving cutting quality; 3)The cutting rate of straws would decrease along with the rising of velocity of vehicle while interval of the moved and fixed blade was determined. And the sawing anti-blocking mechanism had higher cutting quality and lower power consumption without leaky cutting and tearing out with small interval of the moved and fixed blade. Compared with other driving anti-blocking mechanisms, theoretical analysis and experimental results showed that the sawing anti-blocking mechanism had fine cut capability and lower rotation speed (650 r/min) and lower power consumption (power consumption per unit width up to 2.95 kW/m) as well as stronger suitability to different stubbles mulch. Additionally, a new way was found out to improve anti-blocking performance of no-tillage planter.KeyKey wordswords: no-tillage planter; sawing anti-blocking mechanism; cutting mechanism; cutting rate1 1IntroductionIntroduction黑龙江八一农垦大学本科毕业设计- 32 -Anti-blocking issue of no-tillage planter had become one of the key factors affecting production efficiency and seeding quality of two-crop-a-year region in North of China. It was because there was a great deal of crop stubbles and crop seeding was started shortly after crop had been harvested, leaving no time for crop stubbles to decay. At present, there are two methods to solve anti-blocking issue of no-tillage: 1) Straws were chopped by the straw chopper before seeding, it would lead to adding working procedure and increase costs of production as well as delaying seeding time; 2) Stubbles were cleared out by driving chopping mechanism fixed on no-tillage planter, such as Strip Wheat Spinning and Furrow Planter made in Hebei Nonghaha Machinery Ltd Corporation and 2BMDF-Corn Strip Chopper made in China Agricultural University1and so on. In practice the driving chopping mechanism had significant effect on antiblocking, but also bigger vibration and noise as well as lower security because straws were chopped at high rotation speed.It was reported that the blade base linear velocity of several main straw chopping mechanisms was between 3756 m/s2, mostly chopping mechanism combined with cutting and striking had higher striking velocity and higher power consumption3, e.g. the blade base linear velocity up to 34 m/s could obtain fine cutting effect for corn straws4, and 24 m/s on rice and wheat straws by supporting pole, respectively5. Even if corn straws were cut by sliding cut with vertical blade, its velocity of cutting one straw, two straws and three straws must be up to 10.3 m/s, 13.6 m/s, 15.8 m/s6, respectively, and had higher power consumption. In a word, because the driving chopping mechanism developed presently had high rotation speed ( above 1500 r/min ) and higher power consumption (width power consumption per unit up to 1641.74 kW/m, including traction power), to decrease rotation speed and power consumption would be urgent in practice.Based on practical problems, the objective in this paper is to find a way to solve the shortcoming that it 64 is difficult for common smooth blade to seize straws and it must run at higher rotation speed, decrease power consumption and improve cutting effect as well as anti-blocking performance of no-tillage planter. Additionally some experiments were done by selecting saw-tooth as cutting blade of no-tillage planter and cutting 黑龙江八一农垦大学本科毕业设计- 33 -mechanism of the sawing anti-blocking mechanism was investigated.2 2StructureStructure andand cuttingcutting rulerule ofof thethe sawingsawing anti-blockinganti-blocking mechanismmechanism2.12.1StructureStructure andand characteristicscharacteristicsThe sawing anti-blocking mechanism was made up of saw-tooth blade, throwing ban device, principal shaft, moved and fixed blade combination, covering shell, opener and working frame as well as transmission system. Sketch of the sawing anti-blocking mechanism is shown in Fig. 1. The main parts included saw-tooth blade, throwing ban device as well as fixed blade combinations. Diameter of saw-tooth with 60 teeth was 350 mm; throwing ban device with max 270 mm turning diameter was fixed on between adjacent saw-teeth; fixed blade combinations consisted of fixed blade with tooth and vertical type blade, and tooth type blade same to saw-tooth, Moreover, the vertical type blade would be used to obstruct straws without cutting from throwing area and participated in cutting straws. The sawing anti-blocking mechanism was fixed on the soil bin device, its width was 600 mm, the interval of adjacent openers was 200 mm. The sawing anti-blocking mechanism had many characteristics such as straws would be chopped by saw-tooth blade and fixed blade combinations, and had two cutting modes with susta-ining and no-sustaining cutting, the blade base line velocity of saw-tooth was lower to tossing blade type, namely, the sawing anti-blocking mechanism could change higher speed hewing into lower speed sawing.2.22.2CuttingCutting principleprincipleThe sawing anti-blocking mechanism was driven to reverse rotation by power. First, straws were cut in no-sustaining mode by saw-tooth blades while saw-tooth blades touched straws, then after straws were completely cut down, they would be free and be thrown to the rear of opener by throwing ban device and inertial force. Second, straws not being completely cut down would be thrown to former upward and be cut in sustaining mode by fixed blade combinations until any of straws would be cut down, straws having been cut down were thrown to the rear of opener by throwing ban device and saw-tooth. In turn, time after time, straws would be carried out continuously to cut and throw by the sawing anti-blocking mechanism. The lowest point of the saw-tooth blades kept 1530 mm interval from the soil. In terms of spreading status of straws in 黑龙江八一农垦大学本科毕业设计- 34 -field existed perpendicularity or certain angle with marching direction, saw principal in landscape orientation had been determined for the sawing anti-blocking mechanism in order to decrease repeated cutting, leaky cutting and tearing out.Working procedures of the sawing anti-blocking mechanism were as follows: 1) no-sustaining cut phase: static straws relative to ground were cut firstly atNpoint by saw-tooth blades, then, straws would be cut down completely or embedded in saw-tooth. Straws being cut down completely would be free and 65Liao Qingxi et al: Design of anti-blocking mechanism for no-tillage planter dropped into adjacent saw-tooth; 2) dragging and delivering phase: after straws dropped into adjacent saw-tooth, they would be thrown to former upward by the throwing ban device, moreover, straws embedded in the saw-tooth would be thrown to former upward by the saw-tooth at higher speed rotation; 3) sustaining cut phase: straws not being cut down completely in no-sustaining cut phase would be cut in sustaining mode by fixed blade combinations atK point until any of straws would be cut down completely; 4)throwing phase: straws being cut down were thrown directly to the rear of opener by tooth former slanting angle of the saw-tooth and throwing ban device, time and again, straws would be carried out continuously to cut and throw. The working principle of the sawing anti-blocking mechanism is shown in Fig.2.2.32.3AnalysisAnalysis ofof mechanicsmechanics characteristicscharacteristics ofof saw-toothsaw-tooth bladeblade Cutting properties of saw-tooth to cut straws belong to wriggly cut of no-metal materials, its ultimate objective is not only to improve surface cutting quality, but also to raise cutting efficiency, so it can decrease sawing force and power consumption9. Because the ratio of its diameter 350 mm to its thickness 1.8 mm is over 150, the saw-tooth blade belongs to exceed thin disc. It is as plane stress and no-axis symmetry problem according to elasticity theory. And because the saw-tooth blade was tighten by flange tray, six freedoms of its center hole were restricted, so its center parts could be regarded as restricted status completely not to bring any displacement and rotation. Saw-tooth blade belongs to excessive blade tools, it would bring to alternative sawing forces in cutting straws, The reasons lied in: 1) structure of straws with inner empty and outside 黑龙江八一农垦大学本科毕业设计- 35 -hardness had determined micro-hardness un-uniformity distribution, so the single tooth force would be uncertain in cutting straws; 2) the total sawing forces of saw-tooth in horizontal direction would be uncertain because the tooth of saw-tooth blade is not continuous. These alternative characteristics would bring to transfiguration of the saw-tooth, moreover, the transfigured properties an size was relative to the stress properties and size of the saw-tooth in supporting outside loading. So, it was very essential to make clear stress distribution of the saw-tooth in order to ensure smooth cutting.The stress distribution of the saw-tooth blade was calculated by the ANASYS finity element software. Number of the tooth participating in cutting straws was determined to 23 teeth while diameter of straws was in 2045 mm11. The saw-tooth made in 65Mn ofEequal to 210 GPa12andto 0.28 was separated into 1200 cells and 1260 nodes by trapezia gridding. Thus the stress distributions ofX,YandXYplane had been obtained by the ANASYS software according to the most average wring value 26.8 Nm13of the saw-tooth to cut straws by the wring sensor. The stress distributions are shown in Fig.3. Calculated results showed: 1 ) the saw-tooth blade had acted as alternative stress from the whole stress distribution of sawtooth, tooth and around center hole of the saw-tooth had been distributed primary stress, the biggest pressing stress was up to 70776 Pa, moreover, the biggest pulling stress up to 19945 Pa. Compared with yield fatigue intension 735 MPa12of the saw-tooth, the saw-tooth blade was difficult to be destroyed, so it would be feasible to cut corn straws; 2)Fig.3 showed, around stress distribution of the saw-tooth blade was in symmetry distribution, the area of relative bigger stress only occupied 3.33% of the saw-tooth whole area, the other 96.67%; 3)the former tooth of saw-tooth supported the biggest forces among the whole saw-tooth while the former tooth of the saw-tooth touched firstly straws, and its stress value was the smallest before cutting straws, but when saw-tooth started to cut straws, the stress value would increase 66 Vol.19, No.5 Transactions of the CSAE Sept.2003 sharply, its values would be over 105times comparing with the stress values before saw-tooth started to cut straws. However the stress would be down to the lowest point while saw-tooth had finished cutting straws. Thus, the saw-tooth was acted as alternative stress.3 3ResultsResults andand discussiondiscussion黑龙江八一农垦大学本科毕业设计- 36 -3.13.1ExperimentsExperiments andand analysisanalysis ofof rotationrotation directiondirection ofof thethe saw-toothsaw-tooth bladeblade forfor cuttingcutting qualityqualitySome experiments were done by clockwise and counter-clockwise rotation of the saw-tooth blade in the soil bin device. The results are listed in Table 1. TableTable 1 1ExperimentalExperimental resultsresults ofof rotationrotation directiondirection ofof thethe saw-toothsaw-tooth bladebladeTable 1 showed that the way of cutting straws at counter-clockwise rotation would be of benefit to improve cutting quality and throwing effect, and boost up adaptability of weight of different stubble mulch. Therefore, counter-clockwise rotation direction of the saw-tooth blade had been determined.3.23.2EffectEffect ofof thethe rotationrotation speedspeed onon cuttingcutting qualityqualityThe experiments were done by selecting velocity 0.3 m/s of vehicle and interval 5 mm of the moved and fixed blade, and spacing 20 mm between the saw-tooth and ground as well as weight 11250 kg/hm2of the straws mulch, experimental results are shown in Fig.4. The results indicated that the power consump-tion and cutting rate would increase with rising of rotation speed of the saw-tooth blade. Because the wring values of cutting straws were equal basically on the same working condition, the cutting rate could be up to 100% while the rotation speed of the saw-tooth blade was above 650 r/min. It was because the probability rate of the saw-tooth blade to cut straws 67Liao Qingxi et al: Design of anti-blocking mechanism for no-tillage planter would increase with rising of rotation speed whenweight of straws was fixed. 黑龙江八一农垦大学本科毕业设计- 37 -Fig.4Relationships among rotation speed, cutting rate and power consumption3.33.3EffectEffect ofof thethe strawstraw moisturemoisture onon cuttingcutting qualityqualityThe straw moisture of the same crops is different for different autumn and reaping time. The moisture were 20%, 40.5%, 64.4% and 80.16% respectively, after corn straws had been placed in field for different periods. Experiments were done by selecting velocity 0.3 m/s of vehicle and interval 5 mm between the moved and fixed blade and spacing 20 mm between sawtooth and ground, and rotation speed 650 r/min as well as mass 11250 kg/hm2of straws mulch, the results were shown in Fig.5. Fig.5Results of straws moisture for cutting rate and power consumptionExperimental results show that power consumption decreased with increasing of straw moisture and cutting rate of straws increased with increasing of straws moisture on the same working condition, which had connected importantly with different moisture of straws. Straws would take on bigger hardness and best firmness and fine brittleness when straws moisture was in higher, which demonstrated that it had been easy to finish to cut straws. But straws would take on tired and soft status for fine flexible and toughness when straw moisture was lower, so it would be easy to bring to tearing and wrapping. The saw-tooth blade had fine cutting quality and higher cutting rate while straws moisture was up to 80.16% (Fig.6). However the saw-tooth blade had taken ontearing while straw moisture was up to 20%(Fig.7). 4Conclusions1) A new type of sawing anti-blocking mechanism, which could get rid of some shortcoming that common smooth blade is difficult to seize straws as well as high 黑龙江八一农垦大学本科毕业设计- 38 -rotation speed, was designed according to the anti-blocking requirements of no-tillage planter and need in practice. The sawing anti-blocking mechanism had strong capability to seize straws and lower rotation (650 r/min) speed and lower consumption (power consumption per unit width up to 2.95 kW/m) and higher cutting rate of straws, a new approach was provided for design and development of the anti-blocking mechanism of no-tillage planter.2) The stress distribution of the saw-tooth blade was calculated by the ANASYS finity element software. The results showed that its intension would be difficult to be destroyed and the sawtooth blade was feasible to cut corn straws.3) The sawing anti-blocking mechanism realized an integrated function of directly throwing and cutting straws by counter-clockwise. The straws could be cut down completely by two cutting modes of sustaining and no-sustaining cut. Meanwhile, the straws being cut down completely could be directly thrown to the rear of opener by the former tooth horn of sawtooth blade and throwing ban device.4) Experimental results showed in the soil bin device that: (1) Cutting rate of straws increased with increasing of rotation speed of saw-tooth blade and moisture of straws, and higher moisture of straws would be of benefit to improve cutting quality; (2) Power consumption increases along with increasing of rotation speed, and that decreased with increasing of moisture of straws; ( 3 ) Cutting rate of straws decreased with increasing of velocity of the vehicle while interval between the fixed and moved blade had been determined, and to decrease the interval between the fixed and moved blade would be of benefit to improve cutting quality of straws without phenomena of rearing out and leaky cut, and could decrease power consumption. Compared with the other driving anti-blocking mechanism, the theoretical analysis and experimental results showed that the sawing anti-blocking mechanism had better capability to cut and lower rotate speed and power consumption as well as stronger suitability for different stubbles mulch. 免耕播种机锯切防堵装置设计及其切割机理的研究免耕播种机锯切防堵装置设计及其切割机理的研究黑龙江八一农垦大学本科毕业设计- 39 - 摘要摘要: :针对我国北方旱地一年两熟地区免耕播种机堵塞现象和已有卞动式防堵装置转速高( 1500 r/ min 以上)、功耗大 (单位幅宽达 1641.74 kW/m，含牵引功率)的现实问题，设计了一种新型免耕播种机锯切防堵装置，分析了该装置的切割机理，应用有限元 ANSYS 软件计算了锯齿圆盘切刀的应力分布，得出了锯齿圆盘切刀川于玉米秸秆切割的可行性。上述试验表明:1)该装置采用逆转式作业，兼有无支撑和有支撑两种切割方式，切割彻底，并能借助刀齿前角和抛撒板将已切断秸秆定向抛送到开沟器后方，实现了切割、定向抛撒一体化功能;2)秸秆切碎率随转速和秸秆含水率的增大而增大，秸秆含水率高时有利于提高切割质量;3)秸秆切碎率在动定刀间隙一定时，随前进速度增大而降低，小间隙时无漏切和撕皮现象，切割质量高，功耗小。理论和试验结果表明:与其他卞动式防堵装置相比，锯切防堵装置具有良好的切割性能，其转速低 (650 r/min)、功耗小(单位幅宽为 2.95 kW/m)、秸秆覆盖量适应性强，为改善免耕播种机防堵性能提供了一条新途径。关键词关键词: :免耕播种机;锯切防堵装置;切割机理;切碎率1 1、 说明说明免耕播种机堵塞问题是影响我国一年两熟的北方旱地地区的生产效率和播种质量关键因素之一。这是因为有大量的作物根茬而且在作物收割不久就要进行播种，不留时间使作物根茬腐烂。目前，有两种方法来解决免耕播种机的堵塞问题：1）在播种前用秸秆刀切碎秸秆，这将导致增加的工作程序，并增加生产成本，以及推迟播期; 2）茬被安装在免耕播种机上的切除机构清除，如在河北农哈哈机械有限公司的纺纱地带和沟小麦播种机和中国产农业大学 1 的 2BMDF 玉米地带等等。在实践中，驾驶砍机制在防堵问题上有巨大作用，但是因为秸秆切碎时的高转速，会产生更大的振动和噪声以及降低安全。据报道，几个主要秸秆切碎机制的刀片基础线速度是 37 56 米/秒 2 ，其中大部分是砧板机制结合切割突出了更高的惊人速度和更高的功率消耗 3 ，例如：刀片基础线速度高达 34 米/秒能取得削减玉米秸秆的良好效果 4 ，而大米和小麦秸秆高达 24 米/秒 5 。即使玉米秸秆被与与垂直的滑动切口相切，其切割一个和两三个秸秆的速度必须上升到 10.3 米/秒， 13.6 米/秒， 15.8 米/秒 6 ，并且有较高的功率消耗。简言之,因为驾驶砍机制目前开发有高旋转速度(上面 1500 转/分 )并且更高的力量消费(宽度黑龙江八一农垦大学本科毕业设计- 40 -单位能耗高达 16 41.74 千瓦/米，包括牵引动力),在实践中以减少旋转速度和力量消费将是迫切的.根据实际问题，本文件中的目标是要找到一种办法来解决 64 个缺陷，制造出对抓住稻草并且它必须在更高的旋转速度下，减少能耗和提高切割效果以及防堵性能免耕播种机。另外一些实验，对选择了齿形切削刀片的免耕播种机和切削机理的锯切防堵机制进行了研究。2 2 结构和规则的锯切防堵装置的切割原理结构和规则的锯切防堵装置的切割原理2.12.1 结构和特性结构和特性锯切防堵装置由锯齿圆盘切刀、定刀组合、抛撒板、主轴、罩壳、机架、以及传动系统组成。锯切防堵装置的零件图如图 1.其中锯齿圆盘切刀、抛撒板、和定刀组合是该装置的主要组成部分。设计的锯齿圆盘直径为 350 mm,60齿;抛撒板安装在相邻两锯齿圆盘间,其最大回转直径为 270 mm;定刀组合由锯齿形定刀和直刀形定刀组合而成,锯齿形定刀与锯齿圆盘切刀配合对秸秆进行剪切,而直刀形定刀主要起阻挡未切断秸秆落入抛撒区的作用,同时也参与剪切。该装置安装在土槽试验台上,工作幅宽为 600 mm，相邻间隔为 200 毫米。其工作特点是秸秆既可由锯齿切刀直接切碎,也可由锯齿切刀和定刀组合作用而切碎,兼有无支撑与有支撑 2 种切割方式,锯齿刀端线速度低于甩刀式切割器线速度,即具有将高速砍切变为低速锯切的特点。1.开沟铲组合; 2.锯齿圆盘切刀; 3.秸秆导向板; 4.定刀组合; 5.主轴; 6.抛散弧板；黑龙江八一农垦大学本科毕业设计- 41 -7.罩壳; 8.机架;