转子瞬时转速信号中含有丰富的碰摩特征信息,而且基本不受不对中、不平衡等常见故障的影响,可望用于转子碰摩故障的诊断,据此利用仿真和实验手段研究早期碰摩故障时转子的瞬时转速变化规律.建立了考虑转子瞬时转速变化的碰摩动力学模型,通过一阶共振转速范围内的计算求解,发现随着转速的升高,依次会发生不碰摩-单点碰摩-局部碰摩现象,且转速波动幅度会依次增大；单点碰摩和局部碰摩时的瞬时转速波动频谱均以转频为主要分量,但单点碰摩时包含较多的高阶倍频分量,局部碰摩时高阶倍频分量较弱.然后,搭建转子碰摩实验平台,分别进行了不碰摩、单点碰摩和两种不同程度的局部早期碰摩故障的模拟,实测的瞬时转速波动和频谱分析结果与仿真结果相一致,证明了转子瞬时转速波动信号可以指示碰摩故障的发生和严重程度,可为转子碰摩故障提供新的诊断思路和途径.%The rotor transient speed fluctuation signal contains so much rub-impact information which is hardly influenced by faults such as imbalance, so it can be used to diagnose early-stage rub-impact faults between the rotor and the stator. The rotor transient speed fluctuation rules were studied in simulation and experimentation. Firstly, the simulation model of rub-impact is established for speed fluctuation. Secondly, the model was used to find solution under the first order sympathetic rotating speed. It is found that the phenomena of one-point rub-impact, local rub-impact happen in turn with an increase in speed and the rotor transient speed fluctuation amplitude rises in turn. The main component in frequency spectrum is the rotating frequency in one-point rub-impact or local rub-impact. But the amplitude of high order multiple frequency with one-point rub-impact is stronger than that with local rub-impact. Finally, experiments on normal status, one-point rub-impact and two different degrees of local rub-impact were carried out respectively. The results reveal that the actually-measured rotor rotating speed fluctuation signals and their frequency spectrum analysis outcome are consistent with the results obtained in simulation. So the rotor rotating speed fluctuation signals can indicate rub-impact faults and the degree to which faults occur so as to offer a new diagnosis approach to rub-impact fault.
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