Machine Tool Vibration Diagnosis Using Bidirectional Frequency Sweeps
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Solution Overview
Problem
Existing machine tool vibration diagnosis methods struggle to determine if detected resonance frequencies indicate machine tool abnormalities, such as loose bolts, due to the difficulty in distinguishing between normal and abnormal vibrations.
Innovation Solution
A machine tool system that sends oscillation signals with increasing and decreasing frequencies to measure physical quantities, calculating corresponding frequency characteristics to identify abnormalities by comparing the differences between these characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency characteristics are measured using a single oscillation signal, then the measurement process is simple, but it is impossible to determine whether detected resonance frequencies indicate machine tool abnormalities
Solution Approach 1:
The patent segments the measurement process into two distinct parts: measuring frequency characteristics with an oscillation signal whose frequency increases over time, and measuring frequency characteristics with an oscillation signal whose frequency decreases over time. By comparing results from these two separate measurements, the system can determine whether detected resonance frequencies indicate machine tool abnormalities, thus resolving the contradiction between measurement precision and process complexity.
Solution Approach 2:
The patent changes the frequency parameter of the oscillation signal over time in two different directions (increasing and decreasing). By measuring frequency characteristics under these different frequency variation conditions and comparing them, the system can identify abnormal vibrations with higher precision without requiring overly complex measurement equipment.
2Measurement precision
If multiple oscillation signals are used to measure frequency characteristics, then vibration abnormality detection accuracy is improved, but the measurement time increases
Solution Approach 1:
The patent employs continuous oscillation signals whose frequency varies continuously over time (increasing or decreasing) rather than using discrete frequency steps. This continuous measurement approach allows for efficient data collection that improves vibration abnormality detection accuracy while minimizing the total measurement time required.
3Measurement precision
If frequency characteristics are measured with oscillation signals of varying frequency, then it becomes possible to identify abnormal vibrations, but the complexity of signal processing increases
Solution Approach 1:
The patent creates a mirrored measurement process by using both frequency-increasing and frequency-decreasing oscillation signals. The comparison between these two copied measurements provides a reference framework that simplifies the identification of abnormal vibrations, as true abnormalities will manifest consistently across both measurement directions while normal variations will not.
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 effective detection of machine tool abnormalities by highlighting deviations in resonance points between frequency characteristics, facilitating intuitive identification of vibration-related issues.
Implementation Method 1
a first oscillation signal, the first oscillation signal being configured to cause the drive shaft of the servo motor to swing periodically
Implementation Method 2
calculate a first frequency characteristic based on a measurement signal of the physical quantity measured by the measurement unit when the drive shaft swings in accordance with the first oscillation signal
Data Source
AI summary
A machine tool includes: a first calculator configured to calculate a first frequency characteristic based on a first oscillation signal and a measurement signal of a physical quantity measured by a measurement unit when the drive shaft of a servo motor swings in accordance with the first oscillation signal; and a second calculator configured to calculate a second frequency characteristic based on a second oscillation signal and a measurement signal of the physical quantity measured by the measurement unit when the drive shaft of the servo motor swings in accordance with the second oscillation signal.