【摘要】 为了揭示铃壳物理参数对机采棉采摘力学特性的影响规律,该研究以新疆石河子地区具有代表性的3个机采棉品种(新陆早45号、新陆早66号、新陆早83号)为研究对象,通过室内棉花拉伸分离试验对比分析了3种机采棉在相同生长条件下,铃壳质量分数、心皮角以及锁角对棉花铃壳分离力的影响。试验结果表明:3种机采棉的棉花铃壳分离力范围分别为:0.155～0.980 N、0.275～0.967 N、0.258～0.667 N。在室内棉花拉伸分离试验中,3种机采棉棉花拉伸载荷-位移曲线相似,均表现为3个阶段:类弹性阶段、类屈服阶段、分离阶段,在类屈服阶段,棉花拉伸载荷-位移曲线出现锯齿状波动,当外部载荷达到一定程度时棉花内部的棉纤维组织发生局部错位。进一步研究表明,3种机采棉的铃壳质量分数、锁角、心皮角均对棉花铃壳分离力具有显著影响(P<0.01),呈负相关关系,且心皮角、铃壳质量分数与棉花铃壳分离力满足幂函数关系。研究结果表明,在机采棉作物育种时,应尽可能选育铃壳质量分数相对较小、锁角均匀的品种,在选择采收时机时,棉花成熟后应及早采收,避免收获前损失增大。该项研究成果对于指导机采棉育种以及新型棉花收获机械的设计和优化具有理论研究价值和现实意义。更多还原

【Abstract】 Mechanical harvesting technology of cotton has been increasing in modern agriculture in China, particularly for cotton serving as an important strategic reserve material. In mechanized harvesting of cotton, mechanical properties of machine-harvested cottons have become the key factors to cotton harvesting, even to the design of harvesting machinery. The machine-harvested cotton can fall off early in a bad weather after maturity, due mainly to the physical parameters of boll shell, resulting in the loss of pre-harvest cotton. Sometimes the cotton cannot be completely harvested, but the cotton can be knocked off when mechanized harvesting, resulting in the losses during harvest. The physical parameters of boll shell can be closely related to the mechanical effect of working parts, when the cotton is mechanically harvested, with emphasis on the separation force between the boll shell and cotton. Therefore, it is necessary to reveal the effect of physical parameters of boll shell on mechanical properties of machine-harvested cotton, particularly when designing cotton harvesting machinery. In this study, 3 kinds of representative machine-harvested cottons were selected as the research objects, including Xinluzao 45, Xinluzao 66, and Xinluzao 83, collected from the Shihezi area of Xinjiang, China. A laboratory tensile separation test was used to assess the mass fraction of boll shell, carpel angle, and lock angle for the 3 kinds of machine-harvested cottons under the same growth conditions. The experimental results showed that the separation force between cotton and boll shell were 0.155-0.980 N, 0.275-0.967 N, 0.258-0.667 N, for the Xinluzao 45, 66, and 83 machine-harvested cottons, respectively. Three stage can be divided for the machine-harvested cottons, including the elastic-like stage, yield-like stage, and separation stage, in the laboratory tensile separation tests. In the yield-like stage, the tensile separation curve of cotton showed the zigzag fluctuation with the multiple peaks. It inferred that there were concurrently elastic and plastic deformation of cotton fiber with the dominance of plastic deformation. The internal interlaced and intertwined fiber of cotton tissue can produce local dislocation, when the external load of cotton flower reached a critical value. The mass fraction of boll shell, carpel angle, and lock angle in the machine-harvested cottons have a significant effect on the separation force of cotton from boll shell(P<0.01). A power function relationship can be found between the separation force of cotton boll shells and the carpel angle, as well as the mass fraction of boll shell(P<0.001). The separation force of cotton and boll shell gradually decreased, with the increase in carpel angle and mass fraction of boll shell. There was a significantly negative correlation between the lock angle and the separation force, indicating that the separation force of cotton and boll shell gradually decreased with the increase of lock angle. A recommendation was made that a relatively small weight ratio of shell and a uniform locking angle can be selected, when breeding cotton crops for machine harvesting. The cotton can be timely harvested after maturity, in order to avoid the losses before harvest, when choosing the harvesting time. The finding can provide a sound theoretical and practical guidance for the cultivation of new harvesting cotton, as well as for the design and optimization for the harvesting machinery of cotton.更多还原