Rolling Bearing Vibration Diagnosis Across Variable Rotation Speeds
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Solution Overview
Problem
Existing methods for diagnosing rolling bearing abnormalities in machine tools are inaccurate due to the irreversible mixing of frequency information during envelope processing, which fails to account for varying transfer functions and rotation speeds, leading to inconsistent threshold determination and difficulty in calculating absolute evaluation indices.
Innovation Solution
A method that measures vibrations, performs frequency analysis, and calculates a vibration value by removing the effect of rotation speed using a base and exponent proportional to the angular velocity, followed by determining an evaluation index to accurately diagnose abnormalities, with options for using a vibration sensor, transfer function, and weighted average calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If envelope processing is performed to capture vibrations of multiple frequencies, then vibration information can be collectively obtained, but frequency information is irreversibly mixed and transfer function effects cannot be removed
Solution Approach 1:
The patent segments the vibration signal processing into distinct steps: first performing frequency analysis to obtain frequency components, then selectively applying envelope processing only to characteristic frequency components rather than all frequencies. This segmentation preserves frequency information while still capturing modulation effects, resolving the contradiction between information loss and measurement precision.
Solution Approach 2:
The patent extracts only the characteristic frequency components from the full vibration spectrum before applying envelope processing. By taking out and isolating these specific frequency components, the method avoids irreversible mixing of all frequency information while still capturing the modulation effects needed for bearing defect detection, thus maintaining both information integrity and measurement precision.
2Measurement precision
If threshold is determined by transfer function and rotation speed effect on vibration magnitude, then diagnostic accuracy may improve, but threshold cannot be rationally determined and determination result changes with rotation speed
Solution Approach 1:
The patent changes the parameter used for threshold determination from raw vibration magnitude to vibration magnitude normalized by the transfer function and rotation speed effects. By applying this parameter transformation, the threshold becomes independent of operating conditions, allowing rational determination that maintains diagnostic accuracy across different rotation speeds and improves adaptability.
3Reliability
If vibration magnitude is measured to diagnose bearing abnormalities, then diagnostic information can be obtained, but measurement varies with transfer function and rotation speed making quantitative comparison difficult
Solution Approach 1:
The patent introduces transfer function and rotation speed as intermediary factors that mediate between the raw vibration measurement and the final diagnostic evaluation. By using these intermediaries to normalize the measurement, the method maintains reliable diagnostic capability while achieving accurate quantitative comparison across different operating conditions.
Data Source
AI summary
A method for diagnosing an abnormality of rolling bearing includes: measuring a vibration of a rotator; performing a frequency analysis on the vibration to calculate a magnitude of a vibration at each frequency; calculating a characteristic frequency as a frequency of a vibration from a specification of the rolling bearing and a rotation speed of the rotator at a vibration measurement in the measuring; calculating a vibration value from which an effect of the rotation speed is removed by dividing a magnitude of a vibration at the characteristic frequency by a value including a base and an exponent, the base being a predetermined physical quantity in a proportional relation with an angular velocity of the rotator at the vibration measurement in the measuring, the exponent being a positive number; calculating an evaluation index based on the vibration value; and determining an existence of an abnormality based on the evaluation index.