轴流式玉米脱粒装置钉齿元件优化与试验

Optimization and Experiment of Spike-tooth Elements of Axial Flow Corn Threshing Device

为降低黄淮海地区高含水率玉米果穗脱粒时的破碎率,以轴流钉齿式玉米籽粒收获机的脱粒系统为基础,通过对钉齿工作过程理论分析,优化设计一种弧面钉齿;利用离散元软件(Engineering discrete element method,EDEM),分别对梯形钉齿与弧面钉齿与果穗接触时的受力进行分析,得到梯形钉齿和弧面钉齿与果穗接触时受到的切向力均值分别24. 47、20. 65 N,法向力均值分别为50. 93、45. 47 N。分别采用Q235钢、丁腈橡胶套和聚氨酯橡胶材料制作弧面钉齿,以滚筒转速、脱粒间隙、喂入量为变量进行单因素试验,试验材料为籽粒含水率为28%的郑单958。结果表明,当果穗喂入量为10 kg/s、脱粒间隙为55 mm、滚筒转速为300 r/min,采用丁腈橡胶套弧面钉齿和聚氨酯橡胶弧面钉齿脱粒时,破碎率较传统梯形钉齿下降20%,未脱净率不大于1. 02%。该研究可为解决高含水率情况下果穗脱粒装置的设计提供参考。

Corn with high moisture content in Huang-Huai-Hai region of China had a high moisture when it was harvested,which caused high broken rate and un-threshing rate when mechanical harvesting and restricted the development of corn grain harvest. There were many current studies on corn threshing process at home and abroad. But most studies were on the structure of corn threshing machine. Based on the threshing system of axial flow corn threshing device,through the theoretical analysis of working process of spike-tooth,a kind of curved spike-tooth was designed and optimized to solve the problems.The distinct element method(DEM) was a numerical simulation method for dealing with discontinuous medium problems,which was widely used in the field of bulk material processing. Enhanced distinct element method(EDEM) software was a general computer aided engineering(CAE) analysis software based on the DEM,which was commonly used to simulate and analyze particle processing and operating system in industry and agricultural production. The discrete element simulation model of threshing process was established by using discrete element software EDEM,and the normal force and tangential force of trapezoid spike-tooth and curved spike-tooth were determined by studying the mechanism. The simulation result showed that the tangential force of trapezoid spike-tooth and curved spike-tooth was 24. 47 N and20. 65 N,respectively,and the average force of normal force was 50. 93 N and 45. 47 N,respectively.The threshing test was compared with the traditional trapezoidal spike-tooth with different materials. The result showed that breaking rate of Q235 trapezoid,Q235,NBR and polyurethane rubber was 10. 23%,9. 84%,8. 03% and 8. 35%,and un-threshing rate was 0. 53%,0. 92%,0. 77% and 1. 02%,respectively. The corn breaking rate was 20% lower than that of the traditional nail,and un-threshing rate was no more than 1. 02%. The single factor test was carried out with the factors of roller speed,threshing clearance and feeding amount as factors. Zhengdan 958 with grain moisture content of 28% wasset as test material. When using NBR nailed teeth,the feeding amount of corn ear was 10 kg/s,the threshing clearance was 55 mm,the drum speed was 300 r/min,the threshing results showed that breaking rate and un-threshing rate was 8. 03% and 0. 77%,respectively,which had the best threshing effect. The threshing roller was divided into four sections along the axis,and the distribution of the number of falling corn and corn breaking rate in the threshing test were analyzed. The results showed that the first two sections of the drum were the main threshing area of fruit spike,and the amount of falling grain was about 80% of total grain quantity,and the first section of drum was larger in the threshing of the fruit ear,and the corn breaking rate was the highest. The design of the curved spike-tooth not only had reasonable structure but also the material of spike-tooth was easy to replace and the threshing effect was good. It provided a reference for the design of spike threshing device in the case of high water cut.