玉米籽粒收获机双层不平行振动筛设计与试验

Design and Test of Double-layer Non-parallel Vibrating Screens

玉米籽粒收获机清选装置大多采用平行安装的双层筛面,为使双层筛的筛分性能最佳,利用偏置曲柄滑块机构设计了一种多自由度双层不平行振动筛驱动机构,利用矩阵法分析获得筛面的运动方程。选取双层筛筛面安装间距、上筛面安装倾角、筛面横向振幅为试验因素,以玉米籽粒损失率、籽粒含杂率为试验指标,设计二次正交旋转组合试验。利用Design-Expert软件对回归数学模型进行多目标优化,当下筛面安装倾角为3.5°时,机构最优结构参数组合为:筛面前端安装间距292.99mm,上筛面安装倾角3.04°,筛面横向振幅5.55mm。基于优化后的参数,调整驱动机构尺寸进行台架试验,玉米脱出物喂入量为5.05kg/s时,筛分后的籽粒损失率、籽粒含杂率均值分别为1.61%、2.17%,满足玉米收获机械技术标准。相比传统双层平行式平面往复振动筛清选装置,双层不平行振动筛的籽粒损失率平均降低了1.59个百分点。

Most of cleaning devices in maize harvester are parallel-mounted double screen.In order to improve the screening performance of the double screens,a four DOF double-layer non-parallel vibrating screen mechanism and test bench were designed by using the bias crank slider mechanism.The mathematical model of mechanism motion was obtained by using matrix analysis method.The results showed that the sieve movement was non-harmonic periodic motion.The factors were the installation spacing of double screens,the mounting inclination of upper screen,and the transverse amplitude of screen.The indexes were the loss and impurity rate of maize.The test data were analyzed by the response surface method and the regression mathematical models were multi-objectively optimized by using Design-Expert software.When the mounting inclination of lower screen was 3.5°,the optimal parameters were the installation spacing of double screens of 292.99 mm,mounting inclination of upper screen of 3.04°,and transverse amplitude of screen of 5.55 mm.Test of driving mechanism size was done based on optimized parameter adjustment.Under the condition of the normal feed quantity of maize mixture of 5.05 kg/s,the loss rate of grain was 1.61%and the impurity rate of grain was 2.17%after screening,which can meet the performance requirement of maize harvester.Compared with the traditional double plane reciprocating vibrating screen cleaning device,the loss rate of grain was reduced by 1.59 percentage points.