Automated Through-Hole Inspection Using Thermographic Image Masking
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Solution Overview
Problem
Current methods for inspecting through-holes in components, such as turbomachine blades, rely on manual evaluation of thermographic images, which are prone to noise and require subjective interpretation, making them inefficient and labor-intensive, especially for detecting partial blockages in small cooling holes.
Innovation Solution
An automated method that correlates thermographic images with digital images obtained from geometrical data, using a digital image mask to extract through-holes and determine blockages or irregularities, allowing for objective evaluation and reducing the need for manual analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If manual evaluation of thermographic images is used to detect blocked cooling holes, then inspection can be performed, but the process is labor-intensive, subjective, and requires trained personnel
Solution Approach 1:
The patent creates a digital mask based on CAD model data that replicates the expected cooling hole pattern. This digital copy is then overlaid on the thermographic image to automatically identify deviations, replacing manual visual inspection with automated image correlation analysis
Solution Approach 2:
The patent replaces the manual mechanical inspection process with an automated computer-based image processing system that uses algorithmic correlation between thermographic images and digital masks to detect blocked cooling holes objectively and rapidly
2Measurement precision
If standard image processing procedures are used on thermographic images, then analysis can be performed, but high noise components and inhomogeneous illumination due to curvatures make evaluation difficult
Solution Approach 1:
The patent introduces a digital mask derived from CAD data as an intermediary reference layer. This mask serves as a mediator that guides the analysis by highlighting only the relevant cooling hole regions, filtering out noise and illumination variations in the thermographic image that would otherwise interfere with detection
Solution Approach 2:
The patent transforms the inspection approach by changing from direct analysis of raw thermographic image parameters to analysis of temperature deviations from expected patterns defined by the digital mask, thereby converting noise-prone absolute temperature measurements into more reliable relative deviation measurements
3Reliability
If individual contrast adjustments and manual pattern recognition are performed for each thermographic image, then blocked holes can be identified, but the process is time-consuming and subjective
Solution Approach 1:
The patent uses a digital copy of the cooling hole pattern from CAD data to create a reference mask that is consistently applied to all thermographic images, eliminating subjective manual pattern recognition while maintaining reliable detection of blocked holes through automated correlation analysis
Solution Approach 2:
The patent implements an automated feedback loop where the system continuously compares thermographic images against the digital mask, automatically identifies deviations indicating blocked holes, and provides objective results without requiring subjective human judgment, thereby improving both reliability and efficiency
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 enables efficient and accurate automatic inspection of through-holes, reducing testing time and eliminating the need for trained personnel, while improving contrast and sensitivity through the use of heat-up and cool-down cycles in thermographic imaging.
Implementation Method 1
a first and a second thermographic image are generated by passing a heated medium through the through-holes during a heat-up cycle and capturing infra-red radiation emitted from the component during said heat-up cycle, and passing a cooled medium through the through-holes during a cool-down cycle and capturing infra-red radiation emitted from the component during said cool-down cycle
Implementation Method 2
The component is subjected to a heat-up cycle and a cool-down cycle, and a first and a second thermographic image are generated
Data Source
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AI summary
The present invention provides an apparatus and a method for automatic inspection of through-holes of a component. The proposed apparatus (1) includes an imaging module (2), an image processing module (3) and an analysis module (4). The imaging module (2) is adapted for generating a thermographic image (40) of the component (5) by passing a medium through the through-holes (6) and capturing infra-red radiation emitted from the component (5) while the medium is flowing through the through-holes (6). The image processing module (3) is adapted for fitting the thermographic image (40) on a digital image (20, 22) obtained from geometrical data of the component (5). The image processing module (3) is further adapted for masking the fitted thermographic image (40) using a digital image mask (30) to extract regions (41) corresponding to through-holes in the thermographic image (40). The digital image mask (30) is computed based on a determination of positions (21, 23) of through-holes on said digital image (20, 22). The analysis module (4) is adapted for evaluating the masked thermographic image (50) to determine an irregularity or blockage in one or more of said through-holes (6).