Ball Screw Abnormality Detection Using Motor Current Frequency Analysis
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Solution Overview
Problem
Existing methods fail to accurately detect abnormalities in ball screws of injection molding machines using instantaneous current and voltage monitoring of motors.
Innovation Solution
An abnormality detection apparatus and method utilizing frequency analysis of the alternating current of the motor driving the ball screw, combined with vibration analysis, to identify abnormalities through distribution of frequency components and comparison with normal operation data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If instantaneous current and voltage monitoring of motors is used, then the monitoring system is simple, but the abnormality detection precision is insufficient
Solution Approach 1:
The patent segments the motor current signal into different frequency components through spectral analysis. By dividing the current signal into frequency bands and analyzing each component separately, the system can identify specific frequency patterns associated with ball screw abnormalities, thereby improving detection precision while maintaining relatively simple monitoring hardware.
Solution Approach 2:
Instead of analyzing the entire current signal as a whole, the patent applies partial action by focusing on specific frequency components that are most indicative of ball screw abnormalities. The system performs spectral analysis to extract relevant frequency information from the current signal, concentrating computational resources on the most diagnostic portions of the signal.
2Measurement precision
If frequency analysis of motor current is performed, then the abnormality detection precision is improved, but the computational complexity increases
Solution Approach 1:
The patent segments the frequency analysis into discrete spectral components that can be individually evaluated. By organizing the frequency spectrum into distinct bands and analyzing each component separately, the computational task becomes more manageable while maintaining high detection precision through systematic evaluation of each frequency component.
Solution Approach 2:
The system performs partial spectral analysis by focusing computational effort on specific frequency ranges that are most relevant to ball screw fault detection. Rather than processing the entire frequency spectrum with equal detail, the method concentrates analysis on the frequency components that provide the most diagnostic value.
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
Accurately detects abnormalities in ball screws by analyzing frequency components of motor current and vibration, enhancing detection precision and enabling timely maintenance.
Implementation Method 1
a current sensor configured to detect an alternating current of a motor
Implementation Method 2
information related to a distribution of frequency components obtained by frequency analysis of an alternating current
Data Source
AI summary
An abnormality detection apparatus for detecting an abnormality of a ball screw provided in an injection molding machine includes a current sensor configured to detect an alternating current of a motor for applying a driving force to the ball screw; and a computation unit configured to detect an abnormality of the ball screw based on information related to a distribution of frequency components obtained by frequency analysis of an alternating current detected by the current sensor, and information related to a distribution of frequency components obtained by frequency analysis of an alternating current detected when the ball screw, which is normal, operates.