玉米高速免耕播种机组合式垄台种带清秸装置研制

    Development of the stalk cleaning device of maize high-speed no-tillage seeder on seeding belts

    • 摘要: 针对东北地区玉米秸秆还田后覆盖量大,免耕播种机高速作业过程中堵塞缠绕严重、秸秆清理能力不足的问题,该研究结合大垄双行种植模式,设计了一种适用于高速免耕播种作业的切拨组合式垄台种带清秸装置。基于动态滑切减阻原理,设计了一种变参数对数螺旋线作为滑切圆盘曲线,并通过动力学分析确定了滑切圆盘结构,滑切圆盘两侧设计了偏置清秸拨齿,对滑切圆盘两侧拨齿进行结构设计及参数选取。构建了“垄台土壤-柔性秸秆-清秸装置”离散元互作模型,分析秸秆定位铺放时的拨齿清秸效果,确定拨齿偏角范围为30°~75°,开展二次回归旋转正交试验,得到最优结构参数为:内侧拨齿偏角45.3°,外侧拨齿偏角75.0°。田间试验结果表明:秸秆中量覆盖时,装置在3.0 m/s作业速度下的种带清秸率为92.2%,作业功率为9.024 kW,符合东北地区高速免耕播种需要。研究结果可为高速作业下玉米免耕播种机秸秆清理装置的设计与改进提供理论与技术参考。

       

      Abstract: Conservation tillage has been one of the most modern agricultural technologies in recent years. Stalk returning and no-tillage seeding have been combined to improve the soil's physical and chemical properties. The soil fertility can also be protected to reduce the soil disturbance for the stalk coverage and crop yield. At the same time, the long-term high-intensity tillage and stalk burning have caused serious erosion with the limited content of soil organic matter in Northeast China. It is highly required for the conservation tillage with the high level of agricultural mechanization. However, the existing anti-blocking device for no-tillage seeders cannot fully meet the high requirement of high-speed no-tillage seeding. In this study, a stalk cleaning device was designed to combine the seeding belts, particularly for high-speed no-tillage seeding. The double-row planting mode of large ridges was also selected in Northeast China. A pair of drive discs and stalk cleaning teeth were composed in the combined device. Among them, the profile of the disc blade was utilized as the normalized curve of variable parameter logarithmic spiral. The dynamic sliding cutting was then realized under the curve operation. The stable angle of the interception curve was achieved at 22.5° during dynamic sliding cutting. The curve number of the blade disc was further determined to be 18 using kinematic analysis. The two sides of each disc were equipped with the stalk cleaning teeth. The stalks were fully cleaned inside or outside the ridge. A systematic analysis was implemented to optimize the structural, spatial, and operation parameters of the stalk cleaning teeth. A series of simulation tests were also carried out to clarify the interaction between the device and the stalk under high-speed operation using the discrete element method. The ridge soil model was established using the Hertz-Mindlin and Bonding models. The flexible body of the maize stalk was designed with lengths of 130, 150, and 170 mm, respectively. The positioning and laying of the stalk were set at different angles. The stalk cleaning performance was evaluated under different declination angles of the device. The range of deflection angles was determined to be 30°-75°. An optimal model of ridge soil was constructed with a stalk covering amount of 1.66 kg/m2. The quadratic rotation-regression-orthogonal experiment was carried out using Design-Expert software. The target variables were taken as the operation speed and inner and outer declination angle. The optimal parameters of the device were obtained: the inner and outer deflection angles of the stalk cleaning teeth were 45.3° and 75.0°, respectively. The average working power was 7.653 kW, and the stalk cleaning rate was 95.00%, where the relative errors were 3.06% and 1.35%, respectively. The performance of the device was also verified under different amounts of stalk covering. The stalk covering amounts of 2.06, 1.59, and 0.87 kg/m2 were selected in the field experiments, corresponding to the small, medium, and large stalk covering. The field experiments showed that the ideal performance of the device was achieved in the stalk covering amount of 0.87 kg/m2 at the operating speed of 3.0 m/s. Specifically, the stalk cleaning rate of the anti-blocking device was 96.1%, and the average operating power was 8.219 kW. Once the stalk covering amounts were 2.06 and 1.59 kg/m2, respectively, the stalk cleaning rates of the anti-blocking device were 86.7% and 92.2%, while the average values of operating power were 10.460 and 9.024 kW, respectively. The optimal device has fully met the needs of no-tillage seeding under different stalk covering rates in Northeast China. The finding can also provide a theoretical and technical reference for the anti-blocking devices under high-speed seeding.

       

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