Eddy Current Probe Cross Coil Permanent Magnet Noise Reduction
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Solution Overview
Problem
Eddy current testing in magnetic materials is hindered by noise caused by variations in permeability, leading to reduced detection precision, especially in detecting minute defects.
Innovation Solution
An eddy current probe design featuring a cross coil with an intersecting electric current direction and magnetic field generated by a permanent magnet, where the angle between these directions ranges from 30 to 60 degrees, preferably 45 degrees, to reduce noise from permeability variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If eddy current testing is performed on magnetic materials, then defect detection capability is achieved, but noise from permeability variations increases and detection precision deteriorates
Solution Approach 1:
A permanent magnet is introduced as an intermediary component to generate a magnetic field that saturates the magnetic material in the detection area. This intermediary magnetic field eliminates the influence of permeability variations by maintaining constant magnetic saturation, thereby reducing noise and improving defect detection precision
Solution Approach 2:
The magnetic field strength parameter is changed by introducing a permanent magnet to achieve magnetic saturation in the detection area. This parameter change transforms the magnetic material's permeability from variable to constant, eliminating noise caused by permeability variations and improving detection precision
2Measurement precision
If permanent magnet for magnetic saturation is added to ECT coil, then influence from permeability variations is eliminated, but device complexity increases
Solution Approach 1:
The permanent magnet is merged with the ECT coil assembly to form an integrated probe structure. The magnet is positioned adjacent to the coil, combining the magnetic field generation and eddy current detection functions into a single compact device, thereby minimizing structural complexity while achieving noise reduction
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
Significantly reduces noise signal voltage, enhancing defect detection precision by minimizing noise interference from permeability variations, allowing for more reliable detection of minute defects.
Implementation Method 1
a permanent magnet that generates a magnetic field in a predetermined direction
Implementation Method 2
a magnetic flux generated by an ECT coil to which an excitation current is applied generates an eddy current in a member to be measured
Implementation Method 3
a detection signal representing the magnetic flux generated by the eddy current is obtained as an output signal of the ECT coil
Implementation Method 4
the direction of an electric current flowing through the excited cross coil and the direction of a magnetic field generated by the permanent magnet intersect with each other
Data Source
AI summary
An eddy current probe 1 in accordance with the present invention has a structure in which a cross coil 7 is placed in a predetermined direction relative to permanent magnets 3 and 5 in the following manner. When the probe 1 is erected, the coil 7 is placed between the magnets 3 and 5 so that a direction CD in which the opposing portion 9a (9c) of the first coil 9 is extended intersects with a direction MD in which the magnets 3 and 5 are extended. In the same manner, when the probe 1 is erected, the coil 7 is placed between the magnets 3 and 5 so that a direction CD in which the opposing portion 11a (11c) of the second coil 11 is extended intersects with the direction MD in which the magnets 3 and 5 are extended.