基于平稳随机信号的青贮玉米收获机台架振动测试与分析方法*

青贮玉米收获机作为复杂农田作业环境下的多激励源振动系统,其振动机理难以完全用理论描述,为探究适合研究其振动特性的分析方法,本文搭建了青贮玉米收获机试验台。利用24位INV3062-C1(S)通用型动态测试采集仪器,测试不同转速下揉搓辊、定刀和机架位置的振动。分析该试验台振动幅值的均值、方差、有效值,可近似认为该振动信号符合平稳随机振动特征,获得不同工况下的振动时域特征和振动频率分布规律。结果表明,随着电机转速增加,整机振动强度随之增大,其中,揉搓辊位置的振动幅度最大,机架次之,定刀最小;秸秆喂入工况下,随着转速升高,机架振幅的提升速率高于揉搓辊和定刀,机架对电机转速变化最敏感;玉米秸秆的喂入对试验台振动的影响在低速(900 r/min)和中速(2 000~4 000 r/min)较大,高速(4 500 r/min)时影响较小;试验台振动频率集中在166.7~185 Hz、250.7~269.6 Hz、527~559 Hz、746.8~776.2 Hz、872.9~904.8 Hz区间,主要是电机转动频率的倍频成分;在中、高速,电机的振动对试验台振动影响较大,在低速状态下影响较小。在设计青贮玉米收获机时,可考虑在机架位置布置加强筋、在青贮收获机机架与发动机之间增加隔振,减小振动对青贮玉米收获机的影响。研究结果可为改善青贮玉米收获机整机振动,为复杂农田作业环境下收获机械的设计与优化提供参考。

Vibration test and analysis method of silage corn harvesting machine based on smooth random signal

As a multi-excitation source vibration system in a complex farming environment, the vibration mechanism of the silage corn harvester is difficult to be thoroughly described theoretically. To investigate the analysis methods suitable for studying its vibration characteristics, a silage corn harvester test bench was built in this paper. A 24-bit INV3062-C1(S) general-purpose dynamic test and acquisition instrument was used to test the vibrations of the kneading roll, the fixed knife, and the frame position at different speeds. The mean, variance, and RMS values of the vibration amplitude of the test bench were analyzed. The vibration signal could be approximated as conforming to the characteristics of smooth random vibration. The time-domain characteristics and vibration frequency distribution law of the vibration under different working conditions were obtained. The results show that with the increase of motor speed, the vibration intensity of the whole machine increases, among which the vibration amplitude of the kneading roller position is the largest, the frame is the second, and the fixed knife is the smallest. Under the straw feeding condition, with the increase of speed, the rate of the frame amplitude is higher than that of the kneading roller and fixed knife, and the frame is the most sensitive to the change of motor speed. The influence of corn straw feeding on the vibration of the test bench is larger at low speed (900 r/min) and medium speed (2 000-4 000 r/min), and less at high speed (4 500 r/min). The vibration frequency of the test stand is concentrated in the range of 166.7-185 Hz, 250.7-269.6 Hz, 527-559 Hz, 746.8-776.2 Hz, and 872.9-904.8 Hz, which is mainly the multi-frequency component of the motor rotation frequency. At medium and high speed, the vibration of the motor has a greater impact on the vibration of the test stand and has less impact in the low-speed state. In the design of silage harvester, consideration can be given to arranging reinforcement bars at the frame position and adding vibration isolation between the silage harvester frame and the engine to reduce the impact of vibration on the silage corn harvester. The study results can provide a reference for reducing the vibration of the whole machine of the silage harvester and for the design and optimization of the harvesting machine in the complex farming environment.