Online Monitoring of a Shaft Turning Process based on Vibration Signals from On-Rotor Sensor

To realize online monitoring of workpieces in the machining processes with universal lathes, this paper presents a novel vibration method based on a new On-Rotor Sensor (ORS) technology. The dynamic responses of a turning process were firstly examined by finite element analysis (FEA) and impact test analysis to gain a basic understanding of the vibration characteristics measured by ORS when the workpiece is under stationary states with both fixed-pinned and fixed-free boundaries. Experimental evaluations were then conducted under different depths of cut (DOC) for workpieces turning under both the pinned and free conditions. It has been shown that vibration responses are predominated by a low-frequency mode around 500 Hz and a high mode around 1200Hz, which corresponds to the first two lateral modes of the workpiece. The root mean squared (RMS) values filtered in these two bands allow turning processes with different DOCs and workpiece diameters to be differentiated. Besides, unstable turnings can also be detected by the standard deviation of RMS. These results show the proposed method is very promising for online real-time assessment of manufacturing quality, paving fundamentals for intelligent manufacturing.