Application of the vibro-acoustic signal to evaluate wear in the spindle bearings of machining centres. In-service diagnostics in the automotive industry

The correct, undisturbed operation of machines and their components is one of the essential manifestations of an efficient production process. Continuous observation of a machine behaviour is essential to ensure correct and safe operation. The authors of current research focused on evaluation of the using a vibro-acoustic signal to diagnose the wear of spindle bearings of numeric machine tools applied in the automotive industry. More precisely, the effects of using the roll bearings vibrations for the operational diagnostics of spindles in numerical machining centres were investigated. The following parameters were used for analyzing such signals: the acceleration of vibration, the acceleration envelope and the velocity of the vibration. The first part of the research focused on determining the warning thresholds for the observed parameters. In the next stage of the research, the trends of the measured parameters were observed until the warning thresholds were exceeded and the alarm states occurred. An attempt was made to find the reasons for the observed alarm states by analyzing the frequency spectra of the recorded signals at the points where these states occurred. In addition, the diagnosed machine parts (machine tool spindle) were dismantled and inspected in order to link the damage found with the symptoms observed during the recording of diagnostic signals. The relationship between both the signal values and the condition of the diagnosed components as well as between the measured parameters was clearly demonstrated. In the presented article, the authors describe an experiment during which it was possible to register both the normal and emergency state of the object, which is extremely important in industrial diagnostics because one of its limitations is the lack of data from emergency states. In the final conclusions, the authors confirmed the validity of the assumed thesis that the vibroacoustic signal received from the spindle bearings of machines used in mass production in the automotive industry can be used to diagnose the spindles themselves and detect the symptoms of their wear. What can have a significant impact on the quality of manufactured products. This article summarizes the experimental research to date.