液压剪式柠条平茬机的设计与试验

    Design and test of the hydraulic shear-type Caragana korshinskii Kom. coppicing machine

    • 摘要: 为了提高柠条茎杆的切割截面质量及次年萌发率,并降低柠条平茬过程中的切割功耗,该研究结合柠条的生长环境及簇状丛生的生长特点,设计了一种适用于柠条群体茎杆液压剪式平茬机,系统分析了该设备的结构组成与工作原理,并对切割器进行了理论建模与参数分析,明确了其关键技术参数。为进一步优化切割性能,通过自制液压剪式柠条切割试验台模拟现场切割试验情况,在单因素预试验的基础上,选取液压缸伸缩速度、刀具楔角与切割间隙为试验因素,以峰值切割力、切割功耗和破茬率为目标值进行多因素试验,并建立回归分析模型。通过对回归模型优化分析,得到最优工作参数组合为液压缸伸缩速度为0.09 m/s、刀具楔角为28°、切割间隙为3.0 mm。在此工况下,破茬率为7.1%、峰值切割力为10467.4 N、切割功耗为1640.9 J,试验结果与模型预测值的误差值小于5%,验证了优化模型的有效性与可靠性。最后,通过田间平茬试验测得液压剪式平茬机的破茬率、漏割率和茬高不合格率分别为1.8%、1.5%和3.3%,各项作业性能指标均达到设计要求。该研究对促进沙生灌木机械化收获装备的研制与改进具有重要的理论价值。

       

      Abstract: Caragana korshinskii is one species of the flowering plants in western China. This study aims to improve the cutting surface quality of its stems for the high regrowth rate in the following year. While the cutting force and energy consumption were effectively reduced in the stubble-cutting equipment. A hydraulic shear-type stubble-cutting machine was developed specifically for the clustered growth patterns and arid sandy habitats of Caragana korshinskii populations. A systematic investigation was also made on the structural, working, and mechanical configuration of the machine. Particularly, the theoretical analysis was then carried out to determine the technical parameters for the efficient operation in the field. A hydraulic shear-type cutting test bench was constructed to optimize the cutting performance. An accurate simulation was conducted on the field operations in order to measure the cutting forces and power consumption. A single-factor trial was implemented on the three primary operational factors: hydraulic cylinder extension speed, blade wedge angle, and cutting clearance. Multi-factor experiments were conducted with the peak cutting force, cutting energy consumption, and stubble-breaking rate as the evaluation indicators. A regression analysis model was then established to quantitatively analyze the influence of each factor and their interactions on the cutting performance. The test bench consisted of a cutting assembly, a control measurement, and a hydraulic drive system. In experimental material, the Caragana korshinskii shrubs (aged between three to five years with a consistent growth status and free from pest or disease damage) were bundled, and then cut at 5 cm above ground level. A total of 200 groups were collected, labeled, and immediately tested for data accuracy and reliability. The response surface method was utilized to optimize the regression equation. An optimal combination of the working parameters was determined to be a hydraulic cylinder extension speed of 0.09 m/s, a blade wedge angle of 28°, and a cutting clearance of 3.0 mm. The better performance was achieved, where the stubble-breaking rate reached 7.1%, the peak cutting force was measured at 10 467.4 N, and the cutting energy consumption was 1 640.9 J. The relative error between the experimental and the predicted values remained within 5%, indicating the high accuracy and reliability of the regression model and the optimal parameters. The additional field trials were conducted in the typical sandy land shrub environments, in order to verify the field performance of the equipment. The hydraulic shear-type stubble-cutting machine achieved a stubble-breaking rate of 1.8%, a missed cutting rate of 1.5%, and a stubble height non-conformance rate of 3.3%, fully meeting the expected performance. This finding can provide the theoretical and technical references for the mechanical harvesting of the desert shrubs. Some valuable insights can also be offered to integrate the cutting, collecting, and transporting in the arid and semi-arid ecosystems.

       

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