Laser Drilling Breakthrough Detection for Airfoils
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Solution Overview
Problem
Conventional laser drilling methods for creating cooling passages in turbine airfoils are inaccurate and require heavy processing due to the reliance on limited data points for determining breakthrough, leading to potential damage and inefficiency.
Innovation Solution
A method and system that utilize a sensor to sense process conditions indicative of breakthrough, collecting additional data subsequent to a sensed change in excess of a predefined threshold, allowing for more accurate determination of laser breakthrough through the airfoil without requiring processing at the pulse frequency of the laser drill, and incorporating a back strike protection mechanism to prevent damage to the cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high speed camera with shutter speed of 110 μs or more is used to monitor the laser drill and determine breakthrough, then the drilling status can be monitored, but heavy processing is required to process the large number of frames per second and quickly determine the status
Solution Approach 1:
The patent extracts only the essential breakthrough detection function from the complete high-speed camera system. Instead of processing all camera frames, the system uses a simplified sensor that detects only the specific moment of breakthrough, eliminating the need for heavy frame-by-frame processing while maintaining detection accuracy.
Solution Approach 2:
The patent creates a simplified sensing model that copies only the critical breakthrough detection capability from complex high-speed camera monitoring. The sensor system replicates the essential function of detecting light changes at breakthrough without inheriting the computational burden of processing complete video frames.
2Reliability
If the first frame indicating a decrease in light emanating from the drill triggers the drill to cease operation, then the risk of damaging the airfoil is minimized, but the measurement accuracy decreases due to noise and limited data points
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the sensing signal and compares it against threshold criteria. The system uses feedback loops to verify breakthrough conditions before triggering the stop signal, ensuring that noise or transient fluctuations do not cause premature termination while still providing reliable protection against over-drilling.
Solution Approach 2:
The patent prepares the sensing system in advance to recognize the specific signature of breakthrough conditions. By pre-configuring detection thresholds and criteria based on expected breakthrough characteristics, the system can accurately identify the true breakthrough moment without being triggered by noise, while still maintaining rapid response capability.
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 enhances the accuracy of determining laser breakthrough and reduces processing requirements, minimizing the risk of airfoil damage and improving the efficiency of the drilling process.
Implementation Method 1
sensing a process condition and sensing a change in the process condition in excess of a predefined threshold, the sensed change indicative of a breakthrough of the laser through the near wall of the airfoil
Implementation Method 2
A laser drill utilizing a focused laser beam may also be used to create the cooling passages through the airfoil
Implementation Method 3
The laser drill may utilize a pulsed laser operating at, for example, 5,000 Hz or more
Data Source
AI summary
A method for detecting drilling progress in laser drilling is provided. The method includes sensing a process condition during the drilling of an airfoil, and sensing a change in the process condition indicative of a breakthrough of a laser from the laser drill through a near wall of the airfoil. The method additionally includes continuing to sense the process condition subsequent to the sensed change in the process condition to improve the accuracy of the breakthrough detection.