胡萝卜联合收获机单圆盘对顶切割装置设计与试验

Design and Experiment of Single Disc to Top Cutting Device for Carrot Combine Harvester

针对胡萝卜联合收获过程中对顶切割装置作业后胡萝卜损伤率高、切净率低等问题,设计了一种单圆盘对顶切割装置,并阐述了其主要结构及工作原理。在统计分析胡萝卜基本物理特性的基础上,通过理论计算确定了斜拉式导向齐平对顶机构的两对齐基板间距、拉齐区长度和对齐基板斜边角度等主要结构参数,达到胡萝卜茎叶精准拉齐的目的。以螳螂前肢胫节曲线为原型,将拟合优化后的曲线形状应用至圆盘动割刀和直割刀刃口上,构建切割机构胡萝卜茎叶力学模型,分析其满足胡萝卜被高效切断的条件。对圆盘割刀进行运动学分析,建立圆盘割刀前进方向的运动学模型,确定影响装置工作性能的因素为胡萝卜输送速度和圆盘割刀转速。以胡萝卜收获机夹持输送皮带轮转速(胡萝卜输送速度)和圆盘割刀转速为试验因素,以胡萝卜根茎损伤率、茎叶切净率、切割平整度为试验指标,进行了二因素五水平二次正交旋转组合试验,通过对试验结果进行分析优化,确定最佳参数组合。结果表明,当胡萝卜收获机夹持输送皮带轮转速为113 r/min、圆盘割刀转速为156 r/min时,对顶切割装置性能最优,此时胡萝卜损伤率均值为0.53%、切净率均值为95.41%、平整度均值为94.10%。对优化结果进行田间试验验证,验证结果与优化结果基本一致,作业过程中装置工作平稳。

In order to solve the problems of high damage and low cutting rate of carrots after the top cutting in the process of carrots combined harvesting,a single disc to top cutting device was designed and its main structure and working principle was described.On the base of statistical analysis of carrot basic physical properties,the main structural parameters of the cable-stayed guide flushing to top mechanism were designed,such as the distance between the two flushing base plates,the length of flushing section and the angle of the oblique edge of the flushing base plate,etc.,with which,the purpose of accurate flushing the carrot stem leaf was achieved.Taking the curve of tibia of mantis forelimb as the original form to be fit and optimized and applied to the cutting edge of the movable cuter and straight-fixed cuter of the disc to construct the mechanical model of mechanism-carrot stem leaf,through which to verify and determine the condition for efficient cutting.By kinematic analysis to set up the kinematic model of the disc cuter in the direction of moving ahead,through which,the feeding speed of the carrot and the rotating speed of the disc cuter were determined as the factors affecting the device operating performances.Taking the carrot feeding speed and the disc cuter rotating speed as the testing factor,the damage rate and cutting rate of carrot stem leaf as the testing index,the two factors and five levels quadratic orthogonal rotation combination test was carried out.The testing result was analyzed and the optimal combination of operating parameters were determined that,when the rotating speed of the conveying belt wheel was 113 r/min,the rotating speed of the cuter was 156 r/min,the top cutting device functioned the best with the damage rate and the cutting rate of carrot up to 0.53%and 95.41%respectively,and the flushing degree up to 94.10%,whose field verification testing was met well.The device was operated stably.