针对联合收割机的振动问题,该文以4L-0.2微型联合收割机为研究对象,利用最小幅值点法,通过优化割台与整机的连接点,减小振动能量的传递.首先,对比割台有限元仿真模态和试验模态,验证仿真模型和试验数据的正确性,为后续分析确定模态分析的阶次.其次,利用电机驱动割刀模拟工作工况,发现5、10和15 Hz 3个频率的频谱幅值较大,对整机的振动影响明显.而后,利用激振器作激励源,测量单频激励时分布在拟挂接区域内选定点的振动幅值,以这些点的坐标和振幅为采样,拟合二次曲线,(拟合度取值范围0.879~0.975),得到单频极小振动幅值点.最后,以频谱幅值比例和人体对不同方向振动的敏感度作为影响系数,求出3个频率极小振动幅值点的加权重心,作为连接点的优化解.为了验证优化解的正确性,试验测量该点在工作工况下的振幅,结果表明振幅小于拟挂接区其他各点,为该区域平均加权幅值29.707 m/s2的89.29%,最大振幅点幅值35.044 m/s2的74.92%,达到优化要求.%This paper was aimed to reduce the vibration energy transitivity form the cutting table of the combine harvester to combine. In this paper, the 4 L-0.2 micro combine harvester was chosen as the object, the structure of the machine and the characteristics of the header were analyzed, and the minimum vibration amplitude point of the cutting table was found by using the minimum amplitude point method. Then the finite element modal analysis of the cutting table was carried out by using the modal analysis software Workbench, and the first four order modal frequencies and shapes were obtained, which were also acquired through the modal experiment of the cutting table. The experiment result was proved to be believable by comparison with the finite element modal analysis result. Three different experiments were performed, which included the preliminary experiment, the single-frequency excitation experiment and the verification experiment. In the preliminary experiment, the motor was used to provide the power which was used to drive the cutter installed on the cutting table to reciprocate; the preliminary experiment was done under the condition of low frequency, and 3 different frequencies, which had significant influence on the vibration amplitude of the points, were obtained, which were 5, 10 and 15 Hz respectively. The single- frequency experiments were done on the base of these 3 frequencies. In the single-frequency experiment, a small area that contained the positions of the first four order modal node of the experiment mode was divided out from the experimental area on the cutting table. Some points were randomly chosen in the small area, and the exciter was used to force the cutting table to vibrate. The values of vibration amplitude of the points chosen were obtained, and they were imported into the MATLAB together with the coordinate values of the points. The least square method was used to obtain the fitting curve, which illustrated the relationship between the coordinate value and the value of vibration amplitude of the points. The points that had the minimum value of vibration amplitude were found at each frequency. According to the vibration theory, it could be seen that the value of the vibration amplitude in the time domain was the superimposition of the value of amplitude of each frequency. The weighting factors corresponding to the 3 frequencies were obtained, which were 0.54, 0.3 and 0.16 respectively according to the relationship between the 3 different frequencies obtained from the preliminary experiment. The positions of the points that had the minimum vibration amplitude could be calculated with this set of weighting factors. In the verification experiment, the motor was used to provide the power for driving the cutter installed on the cutting table to reciprocate. The experimental data were calculated and the experimental result was consistent with that of the finite element analysis, and the positions of the points that had the minimum value of the vibration amplitude were obtained, which weighted average magnitude for the region (29.707 m/s2) 89.29%, the maximum amplitude point amplitude (35.044 m/s2) 74.92%. At the end, the optimization scheme which provided the best position for the installation of the cutting table was put forward according to the result.After changing the connection point, the cutting table's structure was analyzed, and the results showed that the structural strength of the cutting table met the requirements.
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