Abstract: In view of the various problems in designing buckwheat vibratory screening equipment, including high dependence on tests in determining operation parameters, high cost for evaluating screening effects at different vibration frequencies, and long development cycle, a multisphere buckwheat grain model was established through manual filling based on EDEM according to the morphological characteristics of buckwheat grains. Additionally, according to the buckwheat grain screening requirements, the whole structure of the singledeck vibration screen and parameters of screen meshes were designed to establish a discrete element model. Meanwhile, numerical simulation of the screening process was separately carried out at 3.5 Hz, 4.5 Hz, and 5.5 Hz. The results showed that, in the same leaning angle of the screen, vibrating direction angle, and amplitude, the conveying capacity of the vibration screen was strengthened with the increase of vibration frequency. More grains that failed to pass the sieve were found in the oversize grain collecting box, where the proportion of grains was 0%, 0.86%, and 4.63% for 15 s, respectively. However, screening loss occurred at 5.5 Hz. Based on the above analysis, the vibration screen would achieve a better effect at 4.5 Hz. Therefore, this study could provide not only a model for discrete element simulation in designing buckwheat production and processing devices, but also a reference for optimizing the operation parameters of buckwheat vibratory screening equipment.

Key words: buckwheat grains, vibration screening, vibration frequency, discrete element, numerical simulation

摘要： 针对荞麦振动筛分设备设计中工作参数的确定对试验依赖性大，不同振动频率下设备筛分效果评价成本高、设备研发周期长的问题。根据荞麦籽粒形态特征，借助EDEM软件采用手动填充法建立荞麦籽粒的多球颗粒模型，根据荞麦筛分需求设计单层振动筛整机结构及筛孔参数，建立荞麦振动筛分离散元模型，并对振动筛在振动频率分别为3.5 Hz、4.5 Hz、5.5 Hz 时的筛分过程进行数值模拟。结果表明：在筛面倾角、振动方向角、振幅相同的条件下，随着振动频率的增大，振动筛输送能力增加，同时筛上物收集箱中所包含未透筛的小颗粒数增加，15 s时筛上物收集箱内小颗粒占比分别为0%、0.86%、4.63%。当振动频率为5.5 Hz时，会造成筛分损失。综合分析，当振动频率为4.5 Hz时，振动筛作业效果较好。本研究可为荞麦生产、加工装备的研发中应用离散元模拟提供模型，也可为荞麦振动筛分设备的工作参数优化提供参考。

关键词: 荞麦籽粒, 振动筛, 振动频率, 离散元, 数值模拟