玉米柔性脱粒滚筒脱粒元件设计与试验

Design and test of corn flexible threshing cylinder element

针对黄淮海地区玉米收获过程中籽粒破碎率和未脱净率高的问题,研发了横轴流式玉米柔性脱粒装置,该装置内安装有带柔性钉齿和弹性短纹杆的脱粒滚筒。基于Hertz接触理论对柔性钉齿与玉米果穗碰撞接触进行了力学分析;基于刚柔系统耦合理论对弹性短纹杆与果穗碰撞进行了动力学分析;通过离散元分析完善了弹性短纹杆参数设计;选取滚筒转速、脱粒间隙和喂入量作为试验因素进行了单因素试验和最优参数组合对比试验。试验结果表明:装置最优参数组合如下:滚筒转速为450 r/min,凹板间隙为40 mm,喂入量为8 kg/s,此时平均籽粒破碎率为2.91%,未脱净率为0.51%,优于常规脱粒装置。

In order to solve the problem of high damage rate of maize kernels and high un-threshing rate during the corn harvest in Huang-Huai-Hai region,a transverse axial flow corn threshing test system is designed,which uses flexible tooth and elastic short rasp bar as the threshing elements. The flexible tooth material is polyurethane,which has high abrasion performance,and the elastic short rasp uses torsion springs as auxiliary elements so that can mitigate the force between the corn ear and rasp bar. With reasonable hypothesis,based on the Hertz contact theory,the stress equation of corn ear under the flexible nail tooth collision is established. Based on the rigid flexible coupling system theory,the force equation of the elastic short stripe and corn ear collision is established. The above analysis indicates that flexible tooth and elastic rasp bar have real potential as new threshing elements to mitigate the force between the corn ear and threshing elements. Through image processing,the corn ear contour map is established. Discrete element analysis software is applied to improve parameters design of elastic short rasp. Simulation experiments were carried out in accordance with the feeding volume of 10 kg/s,and the simulation results improve the device design. Finally,single factor test and optimum parameter combination contrast test were carried out with the rotational speed of cylinder,concave clearance and feeding rate as the test factors.The test results show that the device is superior to the conventional threshing device. It lays the foundation for the next field experiment.