Eddy-Current Flaw Detection Probe With Segmented Magnetic Element Rows
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Solution Overview
Problem
Conventional eddy-current flaw detection probes face challenges in maintaining spatial resolution and signal reproducibility due to positional shifts and circuit complexity, leading to increased crosstalk and interference.
Innovation Solution
The proposed eddy-current flaw detection method and device utilize magnetic element groups evenly spaced in circumferential rows around a column-shaped casing, with distinct switching circuits for each row, allowing for sequential selection of magnetic elements for excitation and detection, reducing positional shifts and circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If coils are jointly used as magnetic field excitation coils and magnetic field detection coils with multiplexers for switching, then the device complexity is reduced, but crosstalk and interference signals increase
Solution Approach 1:
The patent divides the magnetic field coils into separate excitation coils and detection coils. The excitation coils (first and second rows) are dedicated to generating magnetic fields, while the detection coils (third row) are dedicated to detecting magnetic fields. This segmentation eliminates crosstalk and interference signals by preventing the detection coils from picking up excitation signals, while still achieving simplified circuit construction through dedicated switching circuits for each function.
2Device complexity
If there is a positional shift in the axial direction between output channels, then the circuit construction becomes simpler, but spatial resolution and signal reproducibility drop
Solution Approach 1:
The patent applies local quality by positioning detection coils at specific locations relative to excitation coils. The third row detection coils are positioned to detect magnetic fields generated by the first and second row excitation coils at precise axial positions. This localized positioning ensures high spatial resolution and signal reproducibility while maintaining simplified circuit construction through dedicated switching circuits.
3Measurement precision
If coils are arranged in multiple rows with different circumferential positions, then detection coverage is improved, but the positional relationship maintenance becomes more difficult
Solution Approach 1:
The patent uses asymmetric arrangement where the third row detection coils are positioned at different circumferential locations relative to the first and second row excitation coils. Specifically, detection coils are positioned to detect magnetic fields at offset angles, creating an asymmetric pattern that improves detection coverage while the fixed structural relationships simplify positional maintenance.
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
This approach enhances spatial resolution and signal reproducibility while minimizing crosstalk, resulting in improved flaw detection performance with a simplified circuit construction.
Implementation Method 1
eddy-current flaw detection testing that applies a magnetic field that changes over time (AC current or the like) to a conductor
Implementation Method 2
detects when an eddy current, which occurs in the conductor, changes due to flaws
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
An eddy-current flaw detection device is provided that improves spatial resolution of flaw detection signals and signal reproducibility during redetection of flaws, and reduces interference signals with simple circuit construction. The eddy-current flaw detection device comprises a magnetic element group of which a specified number of magnetic elements are evenly spaced in each of at least two rows that are formed around the surface of a column shaped casing that is formed such that it can be inserted into a conductive pipe (not shown in the figures), with one row 11 to 18 being located at a position that differs from the other row 21 to 28 by 1/2 the even spacing in the row direction, and switching circuits for switching the magnetic elements in the respective row of the magnetic element group at time-division. The magnetic elements 11 to 18 of one row function as magnetic field excitation elements that excite a magnetic field by being switched at time-division, the magnetic elements 21 to 28 of the other row function as magnetic field detection elements that detect a magnetic field by being switched at time-division, and the eddy-current flaw detection device performs eddy-current flaw detection of the conductive pipe by detecting each magnetic field that is excited by each magnetic field excitation element 11 to 18 by two magnetic field detection elements 21 to 28 that are each located at positions that differs from the magnetic field excitation elements 11 to 18 by 3/2 the even spacing in the row direction.