正反转动力式玉米切茬防堵装置设计与试验

    Design and experiments of active anti-blocking device with forward-reverse rotation

    • 摘要: 针对西南地区免耕播种作业存在秸秆覆盖量大、秸秆整杆覆盖和地块较小的问题,该研究基于有支撑切割原理设计了一种正反转动力式切茬防堵装置。通过参数分析设计了仿生切茬圆盘刀,对防堵装置进行力学和运动学分析揭示其防堵机理。基于离散元法建立防堵装置的数值仿真模型,选取机具前进速度、刀盘间距、正转转速和反转转速为试验因素,以粘结键断裂数量和功率为试验指标,进行二次回归正交旋转组合试验,得到防堵装置的最优参数组合为:机具前进速度0.98 m/s、刀盘间距60 mm、正转转速150 r/min、反转转速313 r/min。根据最优参数完成样机试制,并进行田间试验。田间试验结果表明,秸秆覆盖量为1.63 kg/m2时,防堵装置对玉米秸秆的平均切断率为95.72%;机具通过性合格,满足西南地区免耕播种作业要求。该研究可为秸秆覆盖量大和秸秆整杆覆盖条件下免耕播种机的设计与改进提供参考。

       

      Abstract: Conservation tillage has been a widely defined practice to maintain crop residues on at least 30% of the soil surface after tillage activities, in order to increase soil organic carbon and microbial biomass for less soil erosion in sustainable agriculture. However, a furrow opener of sowing can be twined and clogged by surface crop residues, leading to seed exposure and break ridge in fields. Furthermore, the current no-tillage seeder equipped with an anti-blocking device cannot fully meet the large crop residues with the whole straw coverage on the small plot in Southwest China. In this study, an active anti-blocking device with down-cut and up-cut was designed for the maize no-tillage planter using the support cutting principle. The bionic enlightenment of the anti-blocking device design was obtained from the movement mode and morphological structure of Batocera Horsfieldi. The profile curve of Batocera Horsfieldi mouthpart was extracted as the cutter edge of the right and left disc coulter using image processing. The parametric equation of the left and right disc coulter teeth was established using the fitting curves. A solution analysis was used to determine the functional relationship of tooth number and tooth height of the left and right disc coulter, according to the geometrical relation. A mechanical model of cutting straw was established to reveal the anti-blocking mechanism. A kinematic analysis was implemented to obtain the motion trajectory of the blade tip in the left and right disc coulter. The discrete element method (DEM) was selected to simulate the operation process of the anti-blocking device. A Hertz-Mindlin with a bonding contact model was also established for the crushable corn straw under EDEM software. Furthermore, the single-factor experiment demonstrated that the down-cut disc coulter was in the right disc type, and the number of teeth was 9. A quadratic regression rotatable orthogonal experiment was carried out to obtain the optimal parameter combination. Specifically, the forward speed, spacing, down-cut speed, and up-cut speed were taken as experimental factors, whereas, the number of broken bonds and power were as the experimental indexes. The Design-Expert was selected to establish the regression model for the number of broken bonds and power. A variance analysis showed that the forward speed presented an effect (0.01 

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