Authors

Abstract

In order to address the challenges associated with wide moisture content variation in corn ears, significant operational fluctuations, and stringent kernel damage control requirements during threshing in experimental plots, a combined rod-tooth and spike-tooth axial-flow corn threshing device was designed. Based on the movement and force characteristics of the cobs during the axial-flow threshing process, the key component parameters of the machine such as the threshing drum, concave screen and flow guide structure were calculated and designed, and the three-dimensional model of the whole machine was built. Taking the discrete element method, the movement behavior of ears in the threshing drum was simulated and analyzed, and the influence of the combined threshing components on the axial transport characteristics of ears was focused on. At the same time, modal analysis of threshing drum was conducted by finite element method, and structural dynamic safety in operation speed range was verified. A multi-factor experiment was carried out on combined axial-flow corn threshing test bench, taking drum speed, feed rate and threshing gap as experimental factors and kernel breakage rate and unthreshed kernel rate as evaluation indexes. In this study, Design-Expert software was used to analyze the experimental results and optimize the parameters. Multi-objective optimization identified an optimal parameter combination with a drum speed of approximately 339 r/min, a feed rate of about 3.6 kg/s, and a threshing gap of around 45 mm. Field validation results showed good agreement with the model predictions, indicating that the combined axial-flow threshing device meets the operational requirements of small plots and exhibits good adaptability and operational stability.

Abstract in Chinese

针对玉米试验小区脱粒作业中果穗含水率分布范围宽、作业工况波动大且籽粒损伤控制要求高的问题，设计了一种杆齿—钉齿组合式轴流玉米脱粒装置。依据轴流脱粒过程中果穗运动与受力特征，对脱粒滚筒、凹板筛及导流结构等关键部件参数进行了设计计算，并建立了整机三维模型。通过离散元方法对果穗在脱粒滚筒内的运动行为进行仿真分析，重点研究组合脱粒元件对果穗轴向输送特性的影响；同时，采用有限元方法对脱粒滚筒进行模态分析，验证其在工作转速范围内的结构动态安全性。以滚筒转速、喂入量和脱粒间隙为试验因素，以籽粒破碎率和未脱净率为评价指标，在组合轴流式玉米脱粒试验台上开展多因素试验研究，并利用 Design-Expert 软件对试验结果进行分析与参数优化。结果表明，滚筒转速对未脱净率影响显著，而籽粒破碎率在试验参数范围内变化较为平缓。经多目标优化得到较优作业参数组合为：滚筒转速约 339 r/min、喂入量约 3.6 kg/s、脱粒间隙约 45 mm。田间验证试验结果与模型预测值吻合较好，表明该组合式轴流脱粒装置在小区作业条件下具有良好的适应性与作业稳定性。