Горные науки и технологии (Dec 2024)
Vibration metrics for informational support in assessing the technical condition of ball mills
Abstract
The technical condition of ball mills, employed in the fine grinding of minerals, ores, coal, cement clinker, and other materials, is dictated by both the operational load and the actual physical state of the equipment. Vibration metrics serve as the most versatile diagnostic parameter for developing an informational profile of equipment in active use. The distinct operational environments of high-powered ball mills with frequency-controlled drive systems – one with an induction motor (FC-IM) and the other with a synchronous motor (FC-SM) – necessitate the development of universal approaches to assessing vibration loading that consider each mill's unique design features and operational modes. This study presents the first analysis of the key interrelated technical characteristics of industrial ball mills, including drum volume, diameter, rotational speed, ball load, total weight, and drive power, enabling a more substantiated approach to selecting technical parameters and operational modes. The installation of a permanent vibration control system on ball mills used for grinding mineral raw materials required the individual determination of technical condition category thresholds for the motor, gear-shaft, and drum. The category thresholds were determined individually for each shaft using statistical classification, under the assumption that coupled components are in a state influenced by the energy potential of damage during staged progression. Standard 'reference' ratios of vibration values across three mutually perpendicular directions were established. Characteristic patterns and sequences of damage progression were identified based on the direct spectra of vibration velocity and acceleration. During the analysis of vibration signal time series, a beat frequency mode was detected, indicating potential damage development within gear elements. Effective informational support for the operational condition of ball mills is achieved through the analysis of overall vibration levels, direct trends in vibration velocity and acceleration, time series of the vibration signal, and both long-term and short-term trend analyses. Vibration velocity trends provide insights into technical condition by assessing operational stability, startup frequency, and maintenance intervals.
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