Roll is a common phenomenon in packing intact rice straw by using current medium and small-sized steel-roll round balers. Through high-speed photography, this research observed and analyzed the roll phenomenon, straw movement in the baling chamber in the roll process and straw movement in the baling chamber in the normal process. Analyses showed that the movement of intact rice straw had a long time relative to the static steel roller was the direct reason for the roll phenomenon in the baling chamber. The mechanics analysis on straw in the baling chamber was carried out. Results showed that the critical condition for forming rotating straw core was that rotating force was greater than the resistance. According to the mechanics analysis, the steel-roll bailing mechanism was improved after the combined steel rolls and the side disk ("the roll-disk type" for short) were designed. Taking disk surface form, straw spreading mode and straw moisture content as test factors, taking the mass of straw when rotating straw was formed as the evaluation index, the single-factor test was carried out. The test showed that Type A disk (flat surface) and Type B disk (5mm straight pick added on the surface) had no significant difference on forming rotating straw. In order to keep the interior wall of the baling chamber flat, Type A disk was adopted in this research. The analysis also showed that the roll-disk type could well adapt to different spreading modes (horizontal, disorderly) and different straw moisture content (12%, 75%). The roll-disk could fasten quick formation of rotating straw. Taking the forming rate of bale (the ratio of bale number formed smoothly and total number in the test) as the evaluation index, separately using two types of bailing mechanisms (steel-roll type and roll-disk type), the experiments of bailing were conducted. Compared with steel-roll type for the forming rate of bale, the experimental results showed that the roll-disk type of bailing mechanism was significantly improved. Under this experimental condition, when the length-width ratio (ratio between the rice straw length and the width of bailing chamber) was less than 1, the forming rate of bale reached 100% using the roll-disk when bailing. The roll phenomenon was effectively eliminated. It shows the roll-disk bailing mechanism can effectively avoid the roll phenomenon in the appropriate length-width ratio.%为解决现有中小型钢辊式圆捆机打捆完整稻秆时出现的缠辊现象,采用高速摄像技术对钢辊式圆捆机卷捆过程中发生的缠辊现象、缠辊过程中卷捆室内稻秆运动状态及正常卷捆时卷捆室内稻秆运动状态进行了观测与分析.分析结果表明稻秆相对钢辊长时间静止是导致缠辊现象发生的直接原因.对卷捆室内稻秆进行力学分析,得出卷捆过程中旋转草芯形成的临界条件为旋转动力大于阻力,依据力学分析结论对钢辊式卷捆机构进行改进,设计了一种钢辊和侧圆盘组合式(简称辊盘式)卷捆机构.以圆盘表面形式、稻秆铺放方式及稻秆含水率为试验因素,以旋转草芯形成时的稻秆质量为评价指标,进行单因素试验.试验结果表明A型圆盘(圆盘表面为平面)与B型圆盘(圆盘表面加装厚度为5mm的一字形拨片)对促进旋转草芯的形成并无显著差异.为保持卷捆室内壁平整性设计采用A型圆盘;辊盘式卷捆机构对不同的稻秆铺放方式(横向铺放、杂乱铺放)及不同的稻秆含水率(12%、75%)均具有较好的适应性,旋转圆盘具有促进旋转草芯快速形成的作用.以草捆形成率(草捆顺利形成次数与总试验次数的比值为草捆形成率)为评价指标,分别利用两种卷捆机构(钢辊式、辊盘式)试验装置进行验证试验.试验结果表明辊盘式卷捆机构相比钢辊式卷捆机构其草捆形成率得到显著提升.在本试验条件下,当长宽比(稻秆长度与卷捆室宽度的比值)小于1时,利用辊盘式卷捆机构进行卷捆时,其草捆形成率达到了100%,有效杜绝了缠辊现象的发生,进一步得出在合适的长宽比条件下,辊盘式卷捆机构可有效避免缠辊现象的发生.
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