Eddy Current Calibration Device for Thickness Measurement Precision
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Solution Overview
Problem
Conventional eddy-current flaw detection devices experience decreased measurement precision due to temperature changes and variations in test object thickness, especially when the distance between the test object and an adjacent body changes.
Innovation Solution
A calibration device for a non-destructive inspection system that uses an excitation coil and a detection coil to apply sinusoidal signals or combined signals of different frequencies, with a calibration processing unit that enters amplitudes and phase differences of the output voltage into simultaneous equations to calibrate detection results at multiple calibration points, accounting for various conditions such as temperature, thickness, and spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional eddy-current flaw detection devices are used, then the measurement process is simple, but the measurement precision decreases when temperature changes or thickness varies
Solution Approach 1:
The patent applies parameter changes by using multiple sinusoidal signals with different frequencies to excite the test object at multiple calibration points with known thicknesses. By measuring the output voltages at these different frequencies and thicknesses, the system establishes a comprehensive calibration model that adapts to various temperature and thickness conditions, thereby maintaining high measurement precision across diverse operating parameters.
Solution Approach 2:
The patent introduces an additional dimension by incorporating frequency as a variable parameter. Instead of using a single frequency, the system measures output voltages at multiple frequencies (e.g., 100 Hz, 200 Hz, 300 Hz) across multiple calibration points. This multi-dimensional approach (combining frequency, position, and known thickness) creates a more robust calibration dataset that accounts for temperature and thickness variations.
2Measurement precision
If multiple calibration points with known thickness are used, then measurement precision improves, but the calibration process becomes more complex
Solution Approach 1:
The patent manages calibration complexity by systematically varying parameters (frequency and position) according to a predefined pattern. Multiple sinusoidal signals at different frequencies are applied sequentially at each calibration point, and the system automatically records the output voltages. This structured parameter variation approach, while comprehensive, follows a clear procedure that balances precision requirements with operational feasibility.
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
Maintains high measurement precision despite changes in temperature, thickness, and spacing between the test object and adjacent bodies by performing calibrations using multiple conditions, ensuring accurate thickness measurements across a wide range.
Implementation Method 1
devices that are calibrated by analysis circuits or the like provided with a sine wave generator, a drive circuit for driving an excitation coil, a sensor comprising an excitation coil and a detection coil
Implementation Method 2
a detection coil that is provided so as to face the test object body and that outputs a voltage in accordance with a magnetic field change generated in the test object body
Data Source
AI summary
A calibration device for a non-destructive inspection/measurement system is provided, including an excitation coil; a detection coil; and a computer that applies a sinusoidal signal or a combined signal including multiple sinusoids having mutually different frequencies to the excitation coil in order to excite a pipe body, and that detects changes in the output voltage of the detection coil. The calibration device calibrates the detection results in the computer by entering, as variables in simultaneous equations, the amplitudes and phase differences of the output voltage of the detection coil at multiple calibration points of known thickness on the pipe body. The calibration device performs calibrations by using multiple different calibration conditions at each of the calibration points, and entering, into the simultaneous equations, the amplitudes and phase differences of the output voltage of the detection coil for each of the calibration conditions.