Eddy Current Probe With Articulated Arm For Non-Circular Holes
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Solution Overview
Problem
Conventional eddy current inspection methods for non-straight or non-circular holes in conductive parts, such as those in turbomachine rotor discs, lack sensitivity and precision due to inadequate contact between probes and the internal surfaces, especially when the holes have varying sections and local curvature.
Innovation Solution
A device with a handle and articulated arms, each carrying an eddy current sensor, is designed to engage the hole without rotation, featuring a curved outer side face and elastic means to ensure contact with the inner surface, and includes guide pieces matching the hole's section for precise scanning by moving sensors along narrow parallel bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional eddy current inspection methods are used with multiple probes broaching the hole surface, then the inspection can cover the hole surface, but the contact between probes and hole surface is insufficient leading to poor sensitivity and precision
Solution Approach 1:
The probe incorporates an articulated arm with elastic means (spring) that allows dynamic adjustment of the probe's position and contact pressure. This enables the probe to adapt to varying hole geometries and maintain reliable contact despite curvature variations, directly resolving the contradiction between coverage and contact reliability
Solution Approach 2:
The elastic means changes the mechanical parameter of contact pressure dynamically, allowing the probe to apply appropriate force to maintain contact with the hole surface while accommodating geometric variations. This parameter adjustment ensures both reliable contact and sufficient inspection coverage
2Area of stationary object
If the probe surface is made large to cover more area during broaching, then scanning coverage increases, but contact precision at the optimum point deteriorates
Solution Approach 1:
The inspection system divides the hole surface into multiple narrow parallel bands, each scanned by a dedicated probe. This segmentation allows each probe to maintain precise contact with a specific region while collectively covering the entire hole surface, resolving the contradiction between coverage area and contact precision
Solution Approach 2:
The system transitions from a single large-area probe to multiple probes arranged in specific spatial dimensions, each responsible for a narrow band. This dimensional arrangement enables simultaneous coverage of large areas while maintaining precise contact at each probe's optimal position
3Reliability
If the handle is made curved to match the hole geometry, then contact consistency improves, but device complexity increases
Solution Approach 1:
The handle is designed with local curvature matching the specific hole geometry being inspected. This localized adaptation ensures consistent contact while keeping the overall device structure relatively simple, resolving the contradiction between contact consistency and device complexity
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 solution enhances the sensitivity and precision of non-destructive testing by maintaining consistent contact and accurately scanning the internal surface of complex hole geometries, effectively identifying anomalies and defects.
Implementation Method 1
Device for non-destructive testing, by eddy currents, of a hole made in a conductive part
Data Source
Figure 1~2
Figure 3~5
AI summary
Eddy current control of a hole that may be non-straight and/or have a non-circular cross-section. The control device comprises a handle shaped and dimensioned to be able to be inserted into said hole, at least one arm (15A) articulated to a support (19) fixed to one end of the handle, an eddy current sensor (23) embedded in this arm and an elastic means (24) for applying external force to the arm against the inner surface of the hole.