苜蓿收割调制机六边异形齿压扁辊设计与试验

Design and Experiment of Conditioning Roller for Alfalfa Mower Conditioner Based on Hexagonal Irregular Teeth

摘要:

针对紫花苜蓿刈割压扁过程存在的碎草率高、茎秆折断损失大等问题，以初花期紫花苜蓿为研究对象，分析压扁过程茎秆弯折角对苜蓿茎秆折断率的影响。结合压扁过程几何与受力关系设计一种六边形辊齿，开展二次回归响应面试验，分析了压扁辊齿数、压扁辊转速及压扁辊间隙对压扁率、碎草率及茎秆折断率的影响，并通过干燥试验验证了六边形辊齿的压扁效果。结果表明，茎秆折断率受压扁辊间隙及茎秆弯折角的影响。当间隙一定时，茎秆折断率随茎秆弯折角增加而降低。当茎秆弯折角一定时，间隙越小茎秆折断率越大。当茎秆弯折角大于等于140°时，茎秆折断率小于10%。压扁辊最佳参数组合为：辊齿数6、压扁辊转速750r/min、压扁辊间隙1.61mm。此时，压扁率为97.12%、碎草率为1.40%、茎秆折断率为1.79%。在温度28~31℃的自然干燥条件下，0~30min内混合破坏的平均干燥速率分别为挤压破坏和弯折破坏的1.43倍和1.97倍。在单株与多株干燥试验中，六边形辊齿压扁后苜蓿在0~30min内的平均质量变化量分别为1.53、5.36g,表现出更好的干燥效果。

Abstract:

In response to the problems of high grass crushing rate and large stem breakage loss during the cutting and conditioning process of alfalfa, focusing on the initial flowering stage of alfalfa, the influence of stem bending angle during the conditioning process on the stem breakage rate of alfalfa was analyzed. A conditioning roller with hexagonal roller teeth was designed based on the geometry and force relationship of the conditioning process, and the effects of the number of roller teeth, conditioning roller speed, and roller gap on conditioning rate, conditioningloss rate, and stem breakage rate were analyzed based on quadratic regression response surface experiment. The conditioning effect of hexagonal roller teeth was verified through drying tests. The results indicated that the bending rate of the stem was influenced by the gap between rollers and the breakage angle of the stem. When the gap was fixed, the breakage rate of the stem was decreased as the bending angle was increased. When the bending angle of the stem was constant, the smaller the gap was, the greater the breakage rate of the stem was. When bending angle was greater than 140°, the breakage rate of the stem was less than 10%.The optimal number of roller teeth, roller speed, and roller clearance for the conditioning roller were 6, 750r/min, and 1.61mm, respectively. The experimental results under this parameter showed conditioning rate of 97.12%, conditioning loss rate of 1.40%, and stem fracture rate of 1.79%. Under natural drying conditions of 28~31℃, the average drying rates of mixed damage were 1.43 times and 1.97 times higher than those of compression damage and bending damage within 0~30minutes, respectively. In the drying experiment, the average qualities changes rates of alfalfa conditioned with the conditioning roller within 0~30minutes were 1.53g and 5.36g, respectively, which showed better drying effect than the traditional conditioning roller.