Abstract
Unbalanced vibrations of axial threshing cylinders on a combine harvester were coupled to each other through a frame. The intensified unbalanced vibration will shorten the working life of the axial threshing cylinder. In this paper, the theoretical modes of the axial threshing cylinder were carried out by using finite element analysis software ANSYS. The axis trajectory and speed fluctuation of the axial threshing cylinder under no‐load state and threshing state were tested and analyzed. According to the amplitude and axis trajectory of the transmission shaft, as well as the variation law of the axial threshing cylinder speed, the influence of rice straw on the vibration under the threshing state was revealed. The rotation speeds of cylinder I and cylinder III were adjusted, and the amplitude of cylinder II transmission shaft was analyzed when cylinder II was under stable condition. Then the disturbance and coupling relationships among the unbalanced vibration of axial threshing cylinders were compared. Test results showed that the rotational frequency of the axial threshing cylinder was not in its resonance interval at rated speed. When the axial threshing cylinder was threshing, the horizontal amplitude increased by 0.366 mm. The vertical amplitude increased by 0.697 mm. The speed decreased from 763 rpm to about 750 rpm. The rotational frequency of the axial threshing cylinder would not cause the resonance. With the feeding of rice, the amplitude of the axial threshing cylinder increased slightly and the operating speed was lower than the rated speed. The unbalanced vibration of the axial threshing cylinder transmitted along the frame and coupled with each other, causing the vibration of the axial threshing cylinder to be intensified.
Highlights
During the rice threshing process, an axial threshing cylinder was wound and restrained by the rice straw, which caused a deviation between the center of mass and the centroid of the axial threshing cylinder
E axial threshing cylinder often exhibited speed fluctuation and unstable load during the threshing process. It could produce nonstationary vibration signals. e vibration signals could provide abundant system dynamics information for monitoring and diagnosing the state of the rotating machine [1]. ere were many rotating mechanisms in a rice combine harvester, but the internal structures were not easy to observe. e vibration characteristics could be analyzed by vibration signals
According to the amplitude and axis trajectory of the transmission shaft, as well as the speed fluctuation law of the axial threshing cylinder, the influence law of vibration caused by rice straw entanglement under the threshing state is revealed. en by analyzing the bearing housing amplitude variation and the change of the transmission shaft axis trajectory, the mutual interference and coupling characteristics among the vibration of the co-frame multicylinder were revealed
Summary
During the rice threshing process, an axial threshing cylinder was wound and restrained by the rice straw, which caused a deviation between the center of mass and the centroid of the axial threshing cylinder. When the axial threshing cylinder rotated, it produced unbalanced vibration and reduced its life. E unbalanced vibration among axial threshing cylinders disturbed and coupled with each other and caused the structural resonance and even the working failure of the axial threshing cylinder. E axial threshing cylinder often exhibited speed fluctuation and unstable load during the threshing process According to the amplitude and axis trajectory of the transmission shaft, as well as the speed fluctuation law of the axial threshing cylinder, the influence law of vibration caused by rice straw entanglement under the threshing state is revealed. En by analyzing the bearing housing amplitude variation and the change of the transmission shaft axis trajectory, the mutual interference and coupling characteristics among the vibration of the co-frame multicylinder were revealed According to the amplitude and axis trajectory of the transmission shaft, as well as the speed fluctuation law of the axial threshing cylinder, the influence law of vibration caused by rice straw entanglement under the threshing state is revealed. en by analyzing the bearing housing amplitude variation and the change of the transmission shaft axis trajectory, the mutual interference and coupling characteristics among the vibration of the co-frame multicylinder were revealed
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