Replaceable Centering Assembly for Eddy Current Probe
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Solution Overview
Problem
Existing eddy current probes used for non-destructive testing of steam tubes in steam generators face issues with probe wobble and loss of centering due to wear on the centering feet, leading to lift-off errors and erratic movement.
Innovation Solution
A replaceable one-piece centering assembly with resilient cantilevered legs and hinged halves is designed to maintain the probe centered within the steam tube, allowing for easy replacement of worn components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional centering feet are used to maintain probe centering, then the probe can be centered in the tube, but the centering feet wear down after thousands of feet of sliding friction wear, causing the sensor to drift out of center
Solution Approach 1:
The patent applies the disposable principle by making the centering feet replaceable components. After the centering feet wear down from sliding friction contact with the tube wall, they can be easily replaced without replacing the entire probe assembly. This resolves the contradiction by accepting that the centering feet have limited service life but maintaining reliability through easy replacement.
Solution Approach 2:
The patent applies segmentation by separating the centering feet from the main probe body, allowing them to be independent replaceable components. The centering feet are attached to the probe body but can be removed and replaced separately, enabling maintenance of centering functionality without discarding the entire probe.
2Force
If the centering feet are made resilient to maintain contact with the tube wall, then centering force is maintained, but the resilient material wears down faster due to continuous friction
Solution Approach 1:
The resilient centering feet are designed as disposable replaceable components that can withstand a certain amount of wear before replacement is needed. This resolves the contradiction by accepting material loss through wear but maintaining force application capability throughout the service life of each centering foot set.
3Duration of action of moving object
If the probe is designed with replaceable centering assemblies, then worn components can be easily replaced extending operational life, but the device structure becomes more complex
Solution Approach 1:
The probe is segmented into modular components including the probe body, centering assemblies, and centering feet. This segmentation enables easy replacement of worn centering feet while maintaining the overall probe structure, resolving the contradiction by organizing complexity into manageable replaceable modules rather than a monolithic design.
Solution Approach 2:
The centering assemblies are designed as universal replaceable components that can be used with different probe configurations. The standardized centering assembly design allows the same component to serve multiple purposes and be interchangeable across different probe types, reducing overall system complexity despite the replaceable nature.
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
The solution effectively maintains signal quality by keeping the probe centered, reducing wear-related issues, and extending the probe's operational life by allowing for easy replacement of abraded centering assemblies.
Implementation Method 1
The resilient portions are radially biased away from the shaft
Implementation Method 2
Eddy current probes operate by coils alternating an electromagnet field onto a conduit as it travels within the conduit
Data Source
AI summary
A centering assembly for an eddy current probe having a shaft comprises a one-piece centering assembly comprising a first half and a second half joined by a hinge. Each of the first half and the second half comprise a plurality of cantilevered legs projecting radially about a central aperture. The centering assembly further includes at least one securement mechanism for securing the one-piece centering assembly about the shaft.