滑剪组合式甘蔗根切装置的设计与试验

    Design and test of sliding shear combined sugarcane basecutter

    • 摘要: 针对甘蔗切割过程中存在的宿根破头率高的问题,该研究通过分析甘蔗茎秆与刀具之间的相互作用关系,设计了一种基于“滑切+剪切”相组合的甘蔗根切装置,旨在提高根切作业质量。首先,通过分析传统圆盘式根切器的无支撑切割与滑剪组合式根切器的有支撑切割的作用原理,表明有支撑切割可以有效降低茎秆的弯曲阻力和惯性力,因此一定程度上阻止了茎秆产生较大的变形,有效保证了茎秆的切割质量,而滑切可有效降低切割阻力。并通过建立茎秆的根切受力模型,对根切器关键零部件的参数进行确定,采用等滑切角式刀片曲线进行滑切作业,滑切角和刀片刃口角分别为40°和45°。基于 ANSYS/ Workbench对根切器进行了静力学分析及模态分析,得到刀具的屈服强度为450~650 MPa,大于刀具所受最大应力102 MPa,最大变形量为4.94×10−5 m,满足使用性能要求。切割电机和喂入电机对应的激振频率分别为 0~6.667 Hz 和 0~11.667 Hz,模态分析结果表明两电机的激振频率远小于根切器的一阶固有频率(60.89 Hz),因此不会引起共振现象,能够保障室内试验的顺利进行。搭建了可调刀盘转速、喂入速度及切割倾角的根切试验台,台架单因素试验结果表明当切割倾角、刀盘转速和喂入速度分别在10°~15°、140~220 r/min、1.1~1.7 m/s时,综合评价值较小,切割质量较优。正交试验方差分析结果表明各因素对综合评价值y均有显著影响;正交试验极差分析表明当切割倾角为15°,刀盘转速180r/min,喂入速度为1.4m/s时为最佳试验水平。经试验验证,此时综合评价值为0.256和0.298,切割质量较优。参考DG/T 117-2021 甘蔗收获机械试验方法对甘蔗破头率进行检验,剪切合格率高达90.4%,破头率降低至10%以下,滑剪组合式甘蔗根切器作业质量满足行业要求。该研究可为新型甘蔗根切器的设计与研制提供理论参考。

       

      Abstract: In response to the problem of high stubble damage rate during sugarcane harvesting, the interaction between sugarcane stalks and basecutter was analyzed, and a sugarcane stubble basecutting device was designed based on the combination of "sliding cutting and shearing cutting" to improve the cutting quality. The principle of unsupported cutting of traditional disc basecutters and supported cutting of sliding shear combination basecutters was analyzed. The result was shown that supported cutting could effectively reduce the bending resistance and inertia force of stems, thus preventing significant deformation of stems to a certain extent, effectively ensuring the cutting quality of stems, and sliding cutting can effectively reduce cutting resistance. The parameters of the key components of the basecutter were determined by establishing the force model of the stem. The sliding cutting operation is carried out using an equal sliding angle blade curve, and the sliding cutting angles and blade bevel angles were 40 ° and 45 °, respectively. The statics and modal analysis of the basecutter were conducted to prevent insufficient tool strength and resonance between the basecutter and the motor during shearing using ANSYS/Workbench. An optimal combination was achieved to fully meet the performance requirements, in terms of structural strength, where the yield strength of the basecutter was 450-650 MPa, while the maximum stress on the basecutter was 102 MPa, and the maximum displacement was 4.94×10-5m. The excitation frequencies of the cutting and the feeding motors were 0-6.667 and 0-11.667 Hz, respectively. The modal analysis results show that the excitation frequencies of the two motors were much smaller than the first-order natural frequency of the basecutter (60.89 Hz). Therefore, the smooth operation of indoor experiments was obtained without any resonance. A basecutting test bench was built with adjustable cutting disc rotational speed, feeding speed, and cutting angle. The results of the single-factor test showed that when the cutting angle, cutting disc rotational speed, and feeding speed were 10 °-15 °, 140-220 r/min, and 1.1-1.7 m/s, respectively, the comprehensive evaluation value y was small and the cutting quality was better. The results of orthogonal experiment analysis of variance showed that each factor had a significant impact on the comprehensive evaluation value y. The range analysis of orthogonal experiments shows that the optimal experimental level is the cutting angle was 15 °, the cutting disc rotational speed was 180r/min, and the feeding speed is 1.4m/s. After experimental verification, the comprehensive evaluation values y were 0.256 and 0.298 at this time, indicated the cutting quality was better. Referring to the DG/T 117-2021 sugarcane harvesting machinery test method, the sugarcane stubble damage rate was inspected. The shear qualification rate was as high as 90.4%, and the stubble damage rate was reduced to below 10%. The operation quality of the sliding shear combined sugarcane basecutter met industry requirements.

       

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