关键词: 故障诊断, 数字微分器, 瞬时转速波动, 振动溯源, 中心差分法

Abstract: The fluctuation analysis of angular speed signal is an effective way to recognize the incipient faults for rotating machinery. In this approach, fluctuation parameter extraction is the key. In current methods, the instantaneous angular speed is estimated by using central difference method. However, there is a significant difference in the magnitude response between central difference method and the differential operation, which will lead to large error in fluctuation magnitude extraction. Under this background, an instantaneous speed estimation method based on digital differentiator is established. The magnitude response of differential operation is approximated by finite impulse response filter in the proposed approach. This method can avoid magnitude attenuation effectively. The magnitude of fluctuation can be obtained with more accuracy for this reason. The effectiveness of proposed method is verified by using some simulations and experiments on a CNC machine tool. The vibration source of the rotary indexing table is identified successfully by using the proposed method.

Key words: Central difference method, Digital differentiator, Error source identification, Fault Diagnosis, Instantaneous angular speed fluctuation