气吸式排种器卸种机构设计与试验

Design and Test of Unloading Mechanism of Air-suction Seed Metering Device

为解决气吸式排种器因吸孔堵塞、种盘振动较大导致的漏播问题和气流扰动引发的投种不均匀现象,优化设计了卸种机构。改进了卸种机构安装位置,确保排种器在携种区能够对种子有较好的吸附作用,防止飞种,同时减少碰撞和弹跳,使得种子在携种区气室末端脱落的概率相比于改进前降低了1.67%。推导出一种适用于卸种轮和种盘之间配合的齿面曲线,并通过ADAMS仿真的方式,提取啮合力、径向力和轴向力3个指标,模拟验证了卸种轮齿设计的合理性,表明该曲线方程适用于不同种盘和吸孔数卸种轮的设计,其啮合平稳可靠,具有良好的通用性。以卸种机构、前进速度和负压为因素进行3因素试验,通过分析不同速度下卸种机构和负压之间的差异性和试验整体方差,确定了影响合格指数、重播指数、漏播指数的关键因素。选取优化后的新卸种机构进行回归分析,通过回归方程得出所设计排种器在10、12、14 km/h作业速度下的最佳作业参数,并进行了试验验证。结果表明:新卸种机构能够有效提高合格指数、降低高速作业漏播指数和粒距变异系数,在作业速度为10~14 km/h、负压为3.43~3.81 k Pa时,合格指数达到96.8%,漏播指数小于等于2.0%,重播指数小于等于1.2%,各项指标优于国标要求。

In order to solve the problem of missing seeding caused by small impurities or damaged seeds blocking suction holes under the action of adsorption force in the process of filling,clearing and carrying seeds,the unloading mechanism was optimized.The installation position of seed unloading mechanism was improved to ensure that the seed metering device could adsorb seeds well in the seed-carrying area,prevent flying seeds,and reduce collision and bounce.The probability of seed falling off at the end of the air chamber in the seed-carrying area was reduced by 1.67%compared with that before the improvement.A gear tooth surface curve suitable for the coordination between the unloading wheel and the seed plate was deduced.By means of ADAMS simulation,three indexes of meshing force,radial force and axial force were extracted,and the rationality of the unloading gear tooth design was verified by simulation.The curve equation can be used to design unloading wheels with different kinds of plate and suction holes,which made the meshing stable and reliable and had good versatility.A comprehensive test was carried out with the unloading mechanism,forward speed and wind pressure as factors.By analyzing the significant difference between unloading mechanism and wind pressure at different speeds and the overall variance of the experiment,the key factors affecting the qualified index,multiple index and missing index were determined.The optimized new unloading mechanism was selected for regression analysis,through regression equation,the optimum operating parameters of the designed metering device at operating speeds of 10 km/h,12 km/h and 14 km/h were obtained,and the experimental verification was carried out.The results showed that the new unloading mechanism can effectively improve the qualified index and reduce the missing index of high-speed operation.When the operating speed was 10~14 km/h and the wind pressure was-3.81^-3.43 kPa,the qualified index can reach more than96.8%,the missing index was not more than 2.0%,and the multiple index was not more than 1.2%.All the indexes were better than the requirements of national standards and can achieve effective seeding.