外文翻译--免耕播种机锯切防堵装置设计及其切割机理的研究

附录 Design of sawing anti-blocking mechanism for no-tillage planter and its cutting mechanism Liao Qingxi1,Gao Huanwen2,Shu Caixia1 Abstract: 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 16 41.74 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. Key words: no-tillage planter； sawing anti-blocking mechanism； cutting mechanism； cutting rate 1 Introduction 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 37 56 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 16 41.74 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 mechanism of the sawing anti-blocking mechanism was investigated. 2 Structure and cutting rule of the sawing anti-blocking mechanism 2.1 Structure and characteristics The 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. 2.2 Cutting principle The 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 15 30 mm interval from the soil. In terms of spreading status of straws in 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 65 Liao 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. 2.3 Analysis of mechanics characteristics of saw-tooth blade 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 fo rces in cutting straws, The reasons lied in: 1) structure of straws with inner empty and outside 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 2 3 teeth while diameter of straws was in 20 45 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 Results and discussion 3.1 Experiments and analysis of rotation direction of the saw-tooth blade for cutting quality Some 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. Table 1 Experimental results of rotation direction of the saw-tooth blade Table 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. 3.2 Effect of the rotation speed on cutting quality The 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 67 Liao Qingxi et al: Design of anti-blocking mechanism for no-tillage planter would increase with rising of rotation speed whenweight of straws was fixed. Fig.4 Relationships among rotation speed, cutting rate and power consumption 3.3 Effect of the straw moisture on cutting quality The 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.5 Results of straws moisture for cutting rate and power consumption Experimental 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 on tearing while straw moisture was up to 20%(Fig.7). 4 Conclusions 1) 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 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 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 :免耕播种机 ；锯切防堵装置 ；切割机理 ；切碎率 1、 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 结构和规则的锯切防堵装置的切割原理 2.1 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； 7.罩壳 ； 8.机架 ； 9.轴承座 ； 10.传感器 ； 11.电缆 ； 12.调速电机 ； 13.台车悬挂臂 图 1 锯齿防堵装置结构示意图 2.2 切割原理 锯齿圆盘切刀由动力驱动作逆时针旋转。首先，当锯齿底部与秸秆接触时 ,锯齿嵌住秸秆进行无支撑切割 ,已切断的秸秆 ,依靠锯齿圆盘切刀的刀齿和抛撒板的旋转作用向后抛送。其次，未完全切断的秸杆在刀齿作用下 ,向前上方运动与定刀组合发生剪 切作用 ,秸秆进行有支撑切割 ,从而完成秸秆的全部切断 ,由锯齿切刀和抛散板将断秆抛送到开沟器后方。如此反复 ,实现秸杆的连续切割和抛送。工作时圆盘锯齿不入土 ,其旋转最低点离地 1530 mm。就田间垂直存在的秸秆的散布情况或某个角度的前进方向而言，锯切防堵装置的横向的锯齿是为了减少重复切割、漏割和撕裂稻谷。 锯切防堵装置的工作程序制如下： 1）无支撑切割阶段：相对地面静止的稻草首先被锯齿片切割，然后秸秆被完全切除或牢牢嵌入锯齿中。已切断的秸秆做自由运动并落到邻近的锯齿上 ； 2 )拖拽交付阶段 :在稻草落下了相邻 近的锯牙齿以后，他们将被抛洒装置向上扔到前者 ,而且，被嵌入锯牙齿的稻草将被更高的速度旋转的锯牙齿向前抛出 ； 3 )支撑切阶段 :在无支撑阶段未被切割的稻草被定刀组合切割直到被完全切割。 4 )抛撒阶段 :正在被切割的稻草直接被锯齿圆盘切刀和抛散弧板扔到开沟器的后面 ,再一次 ,稻草将被连续地切割和抛撒。锯切防堵装置的工作的原理如图 2 所示 1.待切秸秆 ； 2.定刀组合 ； 3.罩壳 ； 4.锯齿圆盘切刀 ； 5.抛撒板 ； 6.开沟器 ； 7.断秆 ； 8.地表 ； 9.放大定刀组合 ； 10.锯齿 型定刀 ； N 为无支撑切割点 ；K 为支撑切割点 ；M 为研究对象 图 2 锯齿防堵装置防堵原理示意图 2.3 锯齿圆盘切刀的力学性能 切割秸秆的锯齿圆盘切刀的切割特性属于无金属材料蠕动切割 ,它的最终的目的是不仅提供切割表面的质量 ,而且提高切碎效率，因此它能减少切削力和能量的消耗 9 .因为它 350 毫米的直径与它 1.8 毫米的厚度的比值超过了 150 ,锯齿圆盘切刀属于超过薄圆盘。它是根据弹性理论的水平压力和无轴对