Ball Screw Vibration Diagnosis Using Peak-Hold FFT Signals
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Solution Overview
Problem
Existing methods for diagnosing damage or wear in a ball screw shaft using FFT-based vibration analysis fail to detect abnormalities due to signal attenuation from arithmetic mean processing when data is acquired at different positions, making it difficult to identify issues in specific parts of the shaft.
Innovation Solution
An abnormality diagnosis device and method that includes a vibration sensor, filter processing, envelope processing, fast Fourier transform, peak hold averaging, and abnormality determination to detect maximum signal intensity at specific frequencies, allowing for precise detection of damage or wear in the ball screw shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If arithmetic mean processing is applied to FFT data from multiple periods to improve SN ratio, then signal-to-noise ratio is improved, but characteristic frequency components are attenuated when data is acquired at different positions
Solution Approach 1:
Instead of applying arithmetic mean processing to improve SN ratio (conventional approach), the patent inverts the approach by using peak hold processing that preserves maximum amplitude values. This inversion allows detection of abnormalities even when vibration data is acquired at different positions along the screw shaft, as the peak hold method retains the strongest signal components rather than averaging them out.
Solution Approach 2:
The patent changes the processing parameter from arithmetic mean to peak hold operation. By modifying how the frequency domain data is aggregated (from averaging to maximum value retention), the system maintains characteristic frequency components while still achieving reliable abnormality detection across multiple sampling periods.
2Reliability
If vibration analysis using FFT is applied to detect screw shaft abnormalities, then bearing and nut damage can be detected, but abnormalities in specific parts of the screw shaft cannot be detected due to signal attenuation
Solution Approach 1:
The patent inverts the conventional signal processing approach by replacing arithmetic mean with peak hold processing. This inversion prevents the attenuation of characteristic frequency components that occurs when averaging data from different screw shaft positions, thereby preserving information about localized abnormalities while maintaining reliable detection capability.
3Area of stationary object
If the nut is moved over the entire region of the screw shaft to detect abnormalities, then coverage is improved, but data from different positions causes signal attenuation when processed by arithmetic mean
Solution Approach 1:
The patent inverts the signal aggregation method from arithmetic mean to peak hold processing. This allows the system to maintain high detection coverage across the entire screw shaft region while preserving signal intensity from different positions, as peak hold retains the maximum amplitude values rather than averaging them down.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate detection of damage or wear in the ball screw shaft by utilizing peak hold averaging to maintain signal intensity, ensuring reliable abnormality determination even when data is acquired at varying positions along the shaft.
Implementation Method 1
a vibration sensor that detects vibration during an operation of the ball screw
Implementation Method 2
a filter processing unit that executes, on a vibration signal acquired by the vibration sensor, filtering processing for extracting a frequency band including at least a characteristic frequency corresponding to a specific frequency of the ball screw
Implementation Method 3
an envelope processing unit that executes envelope processing for the vibration signal after the filtering processing
Implementation Method 4
a frequency analysis processing unit that executes fast Fourier transform processing on a time domain signal after the envelope processing
Implementation Method 5
a peak hold averaging processing unit that executes peak hold averaging processing for frequency domain data for each sampling period in the fast Fourier transform processing
Data Source
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AI summary
To provide an abnormality diagnosis device and an abnormality diagnosis method for a ball screw that can detect an abnormality such as damage or wear that has occurred in a screw shaft. An abnormality diagnosis device for a ball screw includes a vibration sensor (21) that detects vibration during an operation of the ball screw, a filter processing unit (23) that executes, on a vibration signal acquired by the vibration sensor (21), filtering processing for extracting a frequency band including at least a characteristic frequency corresponding to a specific frequency of the ball screw, an envelope processing unit (241) that executes envelope processing for a vibration signal after the filtering processing, a frequency analysis processing unit (242) that executes fast Fourier transform processing on a time domain signal after the envelope processing, a peak hold averaging processing unit (243) that executes peak hold averaging processing for frequency domain data for each sampling period in the fast Fourier transform processing, and an abnormality determination unit (25) that performs abnormality determination for the ball screw based on the frequency domain data after the peak hold averaging processing.