Laser Drilling Backlighting Inspection for Gas Turbine Components
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Solution Overview
Problem
Current methods for inspecting laser drilled holes in gas turbine engine components are inefficient as they require offline visual inspection, leading to increased productivity costs, scrap rates, and light source degradation due to dross and dust accumulation and direct laser beam exposure.
Innovation Solution
An apparatus and method that positions a light source in the path of the laser beam, with a camera having a line of sight view of the light source through the machined shape, using a fluid flow to protect the light source from debris and heat, allowing for in-process inspection and real-time correction of hole parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If backlighting is used to illuminate the component for accurate edge detection, then measurement precision is improved, but the light source degrades quickly due to dross and dust accumulation and direct laser beam exposure
Solution Approach 1:
A transparent shield is introduced as an intermediary between the light source and the harmful environment (laser beam path, dross, dust). The shield protects the light source from direct exposure to the laser beam and debris accumulation while remaining transparent to allow the light to pass through for backlighting the hole. This resolves the contradiction by mediating between the need for accurate illumination and the need to protect the light source.
Solution Approach 2:
The harmful laser beam and debris are converted into beneficial protective elements. The laser beam path itself becomes the protective barrier when the transparent shield is in place - the shield protects the light source from the very environment (laser plasma, dross, dust) that would otherwise damage it. The system uses the existing harmful environment to its advantage by positioning the shield to leverage the laser path as a protective zone.
2Measurement precision
If offline inspection is performed after hole drilling, then measurement accuracy is improved, but productivity decreases due to process stopping and re-drilling requirements
Solution Approach 1:
The inspection process is made continuous by implementing online inspection during the laser drilling process itself. The light source and camera system operates throughout the drilling process, allowing real-time monitoring of hole parameters without interrupting the manufacturing process. This eliminates the need to stop the drilling process for inspection and prevents scrap and re-drilling, thereby maintaining both measurement accuracy and productivity.
Solution Approach 2:
A feedback loop is established where the camera continuously monitors hole parameters during drilling, and this information is used to adjust the drilling process in real-time. The system provides feedback on hole quality during the process, enabling corrective actions to be taken immediately rather than after the fact, thus preventing defective holes and improving overall productivity while maintaining inspection accuracy.
3Measurement precision
If the light source is positioned in the direct path of the laser beam for backlighting, then edge detection accuracy is improved, but the light source heats up and fails due to direct laser exposure
Solution Approach 1:
The transparent shield serves as a thermal and radiative barrier between the laser beam and the light source. It allows optical transmission for backlighting while blocking the harmful thermal effects of the laser beam, thus protecting the light source from overheating while maintaining measurement precision.
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 continuous, accurate inspection and correction of laser drilled holes during the machining process, maintaining consistent lighting and extending light source lifespan by preventing debris accumulation and heat damage.
Implementation Method 1
a device is arranged to provide a flow of fluid over the surface of the light source
Implementation Method 2
the present disclosure relates to an apparatus and a method of laser drilling a hole through a gas turbine engine component
Implementation Method 3
laser drilling a hole through a gas turbine engine component
Data Source
Figure 1
Figure 2
Figure 3~9
AI summary
A method of laser drilling a hole comprising providing a laser source (106) at a first side of a component (42) to laser drill a hole (54A) though the component (42). A light source (108) is positioned in the path of the laser beam (L) at the opposite side of the component (42). A camera (114) is provided at the first side of the component (42). The camera (114) is positioned such that it has a line of sight view of the light source (108) through the laser drilled hole (54A). The laser drilled hole (54A) in the component (42) is viewed using the light provided by the light source (108) at the opposite side of the component (42). The parameters of the laser drilled hole (54A) are measured using the view of the laser drilled hole (54A) provided by the camera (114) and a flow of gas (A) is provided over the surface of the light source (108) to protect the light source (108).