玉米根茬抖动升运机构的建模与优化

Modeling and optimizing dither mechanism for conveying corn stubble

收获玉米根茬过程中,采用碾压方式脱去裹夹于根系中央的泥土颇为有效,然而将根茬输送至碾辊处的过程中,经常出现下滑、堆叠等不良状况,严重影响了物料的有效升运与碾压脱土,因此根茬的有序升运与整列是实现碾压脱土的前提与关键。该文采用理论与试验相结合的方法对该机构进行优化:首先建立玉米根茬在抖动链条上的动力学模型,并确定根茬稳定升运及跳动的临界条件;然后在理论研究的基础上,借助升运试验平台及高速摄像系统,对根茬的升运及跳动过程实施记录和分析,最后确定了抖动升运机构的最优参数组合,升运链的倾角为23°,驱动轮转速为120r/min,抖动轮顶起高度为22mm。系统在最优参数下的试验结果表明:根茬能够随着抖动链条有序上移,并在链条斜面上小幅跳动,能够有效缓解根茬的堆叠、拥堵状态。

One kind of agricultural machine was researched to harvest corn stubble. This machine consists of three subsystems： the excavating subsystem consists of a stubble spade and stubble push device; the stubble soil separation subsystem consists of a fist level screening conveyor chain, fixed roll, and second level screening conveyor chain; and the stubble collect and dump subsystem consists of a stubble collector container and dumping device. The screening conveyor chain is very important to the machine, as in the course of conveying corn stubble, the appearance of slipping off, piling up and clogging affected the harvest performance. In order to improve the dither mechanism performance of conveying corn stubble, the method of Combing theory analysis and experiment research was used to optimize the mechanism. Firstly, the dynamic model of corn stubble which is on the jitter chain was established, then the moving up and jumping critical condition of corn stubble were determined;Secondly, according to theoretical model and structural parameters of the whole system, the theoretical optimum parameters were obtained. The tilt angle of the mechanism is 23°, the rotational speed of driving wheel is 120 r/min, and the height of the chain is 34 mm. At last, by means of a test stand of dither mechanism and high-speed photography system, the moving up and jumping course of corn stubble were recorded and analyzed, The test results show that corn stubble can move up with jitter chain collectively, and corn stubble also can jump steadily.