アンダーサンプリングによって1kHz程度以下の安価な加速度センサーで実現したベアリングの損傷検知

抄録

It is experts’ common knowledge that vibration measurements in the high-frequency band of several kHz to 10 kHz are necessary for precise diagnosis in CBM to detect the damages of rotating elements such as ball or roller bearings. Some cheaper digital output MEMS accelerometers with relatively low maximum sampling frequency may have insufficient anti-alias filtering effects and generate alias noise. However, there is a possibility to utilize the data with alias noise to detect the damage of bearing by frequency analysis from the envelope of the vibration waveform obtained by “under sampling”. If this is true, precision diagnosis of bearings by using inexpensive sensor system can be realized. To confirm this, vibrations in three axial directions were measured at the same timing by digital output MEMS accelerometers （wireless 3D sensor） with a maximum sampling frequency of 3.2kHz, and frequency analysis was performed on the composite waveform. The experimental results show that abnormalities （wound on the raceway of bearings） could be detected with sufficient sensitivity. Furthermore, by using the 3D envelope FFT, the measurement can be performed without concern for the mounting direction of the vibration sensor. This may greatly reduce man-hours and costs for equipment maintenance and enlarge the application of CBM.