Ball Screw Abnormality Detection via Frequency Analysis
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Solution Overview
Problem
Existing methods fail to accurately detect abnormalities in ball screws of injection molding machines due to the complexity of vibration waveforms, and there is a lack of specific methods for analyzing acceleration data to identify issues.
Innovation Solution
An abnormality detection apparatus and method that utilize frequency analysis of vibration intensity and motor current, employing a computation unit to analyze frequency components, calculate center of gravity, and compare with normal operation data to determine abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vibration intensity monitoring is performed on the ball screw, then abnormality detection capability is provided, but detection accuracy is insufficient due to complicated vibration waveform
Solution Approach 1:
The patent segments the vibration waveform analysis by dividing it into frequency components through FFT analysis. Instead of analyzing the complex time-domain waveform as a whole, the vibration signal is decomposed into multiple frequency components, allowing specific abnormality-related frequencies to be identified and analyzed separately, thereby improving detection accuracy
Solution Approach 2:
The patent transforms the vibration analysis from the time domain to the frequency domain by calculating the center of gravity in the frequency domain. This dimensional transformation allows for more effective characterization of vibration patterns and improves the ability to distinguish normal from abnormal operations
2Loss of information
If acceleration data is collected from the ball screw, then vibration information is obtained, but specific abnormality identification method is lacking
Solution Approach 1:
The patent implements a feedback mechanism by comparing the calculated center of gravity with a predetermined threshold value. When the center of gravity exceeds the threshold, the system determines that an abnormality exists and provides appropriate output signals, creating a closed-loop detection system that provides clear feedback on the operational state
Solution Approach 2:
The patent replaces direct mechanical inspection methods with computational analysis. Instead of relying on mechanical measurement techniques or manual inspection, the system uses FFT algorithms and center of gravity calculations to automatically identify abnormalities, substituting mechanical/manual processes with computational ones
Data Source
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AI summary
An abnormality detection apparatus for detecting an abnormality of a ball screw provided in an injection molding machine includes: a vibration sensor configured to detect vibration of 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 a vibration intensity detected by the vibration sensor, and information related to a distribution of frequency components obtained by frequency analysis of a vibration intensity detected when the ball screw, which is normal, operates.