穴粒数可调气吸式棉花精量排种器设计与试验

Design and Experiment of Precision Pneumatic Seed Metering Device with Adjustable Seeds per Hole for Cotton

摘要:

针对长江流域麦后夏直播棉花作业时节降雨充沛，黏重土壤水分蒸发易板结，常规单粒播种易存在出苗破土难、出苗率低等问题，结合该区域内棉花精量直播穴粒数可调农艺要求，本文提出一种通过调节双吸种圆盘重叠空间切换不同吸孔组合，实现单粒吸种、单-双-单粒吸种和双粒吸种的穴粒数单双粒可调气吸式排种器。阐述了其结构与工作原理，设计了关键部件参数。基于DEM-CFD耦合方法解析了型孔直径、排种盘转速和吸种负压对排种性能影响规律。以型孔直径、吸种负压和排种盘转速为试验因素，以合格指数、重播指数和漏播指数为评价指标，进行了正交试验，经台架试验验证最优参数为型孔直径3.3mm、吸种负压4.3kPa和排种盘转速30r/min，此时单粒吸种、单-双-单吸种和双粒吸种合格指数、重播指数和漏播指数分别为：94.1%、93.8%和92.4%，5.34%、4.65%和6.01%，0.56%、1.55%和1.59%。在最优参数组合下进行田间试验，结果表明，当作业速度为6km/h时，排种合格指数大于89.3%，漏播指数小于4.42%，重播指数小于6.28%。单粒排种、单-双-单粒排种和双粒排种出苗率和缺苗断垄率分别为78.98%、80.3%和84.66%，19.24%、18.92%和12.08%，双粒及单双交错播种较单粒播种，缺苗断垄率分别降低7.16、0.32个百分点，出苗率分别提高5.68、4.36个百分点，有效提升保苗率，保证了棉花群体建成，利于机械化一播全苗与高产稳产。

Abstract:

In view of the problems in the Yangtze River Basin, such as abundant rainfall during the post-wheat direct seeding period, easy compaction of heavy clay soil due to water evaporation, difficulty in seedling emergence and low emergence rate in conventional single-seed sowing, combined with the agronomic requirement of adjustable number of seeds per hill for cotton precision direct seeding in this region, a pneumatic seed metering device with adjustable seeds per hill was proposed. This device can realize single-seed suction, single-double-single seed suction and double-seed suction by adjusting the overlapping space of dual seed-suction discs to switch different combinations of suction holes. The structure and working principle of the device were elaborated, and the parameter design of key components was carried out. Based on the DEM-CFD coupling method, the influence laws of seed hole diameter, rotation speed of the seed metering disc and seed suction negative pressure on the seed metering performance were analyzed. Taking seed hole diameter, seed suction negative pressure and rotation speed of the seed metering disc as experimental factors, and qualified index, replay index and miss-seeding index as evaluation indicators, orthogonal optimization experiments were conducted. The results showed that under the optimal parameter combination verified by bench tests, i.e., seed hole diameter of 3.3mm, seed suction negative pressure of 4.3kPa and rotation speed of the seed metering disc of 30r/min, the qualified indexes, replay indexes and miss-seeding indexes corresponding to single-seed suction, single-double-single seed suction and double-seed suction were 94.1%, 93.8% and 92.4%;5.34%, 4.65% and 6.01%;0.56%, 1.55% and 1.59%, respectively. Field experiments under the optimal parameter combination showed that when the operating speed was 6km/h, the qualified index of seed metering was greater than 89.3%, the miss-seeding index was less than 4.42%, and the replay index was less than 6.28%. The later seedling emergence results showed that the emergence rates and the rates of missing and broken seedlings for single-seed sowing, single-double-single sowing and double-seed sowing were 78.98%, 80.3% and 84.66%;19.24%, 18.92% and 12.08%, respectively. Compared with single-seed sowing, double-seed sowing and single-double alternating sowing reduced the rate of missing and broken seedlings by 7.16 and 0.32 percentage points respectively, and increased the emergence rate by 5.68 and 4.36 percentage points, respectively. This effectively improved the seedling preservation rate, ensured the establishment of cotton population, which was conducive to mechanized full seedling emergence in one sowing as well as high and stable yield.