Eddy Current Probe Phase Angle Flaw Detection
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Solution Overview
Problem
Eddy current testing devices face challenges in accurately detecting changes in characteristics of target objects, especially when the changes are small, due to signal interference from lift-off or surface conditions, making it difficult to confirm the presence and location of flaws like cracks.
Innovation Solution
An eddy current testing device that generates image data based on phase angles, plotted in coordinates with position and time, using multiple coils to differentiate between signal components and remove noise, allowing for clearer identification of flaw signals regardless of their magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplitude-based display (C scope) is used to detect changes in target object characteristics, then large changes can be clearly detected, but small changes are hidden by noise from lift-off or surface conditions
Solution Approach 1:
The patent transforms the detection parameter from amplitude to phase angle. By displaying the phase angle of the detected signal instead of its amplitude, the system can distinguish flaw signals from noise based on phase characteristics rather than magnitude, thereby improving detection accuracy for small changes while filtering out lift-off and surface condition interference.
2Reliability
If conventional amplitude display is used, then the inspection process is simple, but the position and presence of small flaws cannot be confirmed
Solution Approach 1:
The system changes the display parameter from amplitude to phase angle, which requires additional signal processing to extract phase information. This increases processing complexity but significantly improves flaw detection reliability, as phase angle display can reliably indicate both the presence and position of small flaws that are invisible in amplitude-based displays.
3Measurement precision
If multiple coils are used to improve detection capability, then signal differentiation is enhanced, but device complexity increases
Solution Approach 1:
The patent divides the detection function into multiple coils arranged in specific patterns (e.g., differential coil configurations). Each coil contributes to detecting different aspects of the eddy current response, enabling the system to differentiate flaw signals from noise through comparative analysis of multiple coil outputs, thereby enhancing measurement precision while managing device complexity through systematic arrangement.
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 accurate detection and specification of changes in target object characteristics by visualizing phase angles and signal relationships, effectively distinguishing between flaw signals and noise, even for small changes, thereby improving the reliability of inspections.
Implementation Method 1
supply an alternating current (exciting current) to a coil provided in an eddy current probe, cause the coil to generate an alternating magnetic flux
Implementation Method 2
cause the eddy current probe to approach the metal body and generate an eddy current, and detect a signal indicating turbulence of the eddy current. The eddy current varies depending on conductivity, permeability and the like of the target object
Data Source
AI summary
An eddy current testing device which confirms that a change in characteristics of a target object is detected regardless of the magnitude of the change and specifying the position of a portion from which the change is detected. The device uses an eddy current probe to inspect a bent portion of a metal body, and has an inspection controller and a display unit. The inspection controller calculates a phase angle of a signal detected by the eddy current probe and generates flaw identification image data that indicates an area (or an area of the signal detected and determined to correspond to a flaw signal, based on the phase angle of the detected signal) of a flaw signal in coordinates in which the position of the portion of the target object is plotted along a coordinate axis. The display unit displays the flaw identification image data.