Laser Drilling Hollow Airfoils Without Internal Wall Back Strikes
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Solution Overview
Problem
Laser drilling of hollow cast components, such as airfoils for gas turbine engines, often results in back striking, which damages internal walls due to the laser energy penetrating the internal cavity, necessitating time-consuming pre-filling and post-processing steps with materials like wax or epoxy.
Innovation Solution
Injecting a fluid into the internal cavity of the hollow component to create a pressure greater than ambient pressure, using a laser beam to drill holes while directing the fluid through the holes to attenuate the laser energy and prevent back striking, with a system comprising a laser generator, fluid source, pump, and collector to manage fluid flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filling materials (wax, epoxy) are used to prevent back striking, then internal walls are protected from laser damage, but the process becomes time-consuming and requires additional filling and post-processing steps
Solution Approach 1:
The patent removes the filling material step entirely from the process. Instead of filling the cavity with wax or epoxy before drilling, the invention uses a fluid (such as water or gas) introduced during the laser drilling process itself to prevent back striking. This extraction of the filling step eliminates the time-consuming pre-filling and post-processing operations while maintaining protection of internal walls through the fluid medium present during drilling.
Solution Approach 2:
The patent introduces a fluid as an intermediary substance between the laser beam and the internal cavity walls. This fluid acts as a mediator that absorbs or scatters the laser energy, preventing direct damage to the internal walls. The fluid can be introduced through the workpiece or into the cavity, creating a protective medium during the drilling operation without requiring permanent filling materials.
2Productivity
If no protective measure is taken, then the drilling process is fast and simple, but the laser energy damages the internal walls of the casting
Solution Approach 1:
The patent converts the potentially harmful laser energy that would otherwise damage internal walls into a beneficial effect. By introducing a fluid medium during drilling, the laser energy is absorbed or scattered by the fluid, preventing damage to internal walls. The same laser energy that could cause harm is thus redirected to accomplish the useful function of drilling through the workpiece while the fluid manages the excess energy.
Solution Approach 2:
The patent employs hydraulic or pneumatic principles by using a fluid (liquid or gas) introduced into or near the internal cavity during laser drilling. This fluid medium, delivered through pressurized systems, serves to attenuate the laser energy and protect internal walls. The use of pressurized fluid delivery systems aligns with pneumatic and hydraulic principles to achieve protection without sacrificing drilling speed.
3Reliability
If filling materials are used to attenuate laser energy, then back striking is prevented, but extra steps of filling and burning/leaching out material are required
Solution Approach 1:
The patent extracts the filling material step from the process sequence. Instead of requiring materials like wax or epoxy to be filled into the cavity before drilling and then removed afterward, the invention uses a fluid introduced during the drilling operation itself. This eliminates both the filling step and the subsequent burning or leaching out step, reducing process complexity while maintaining back strike prevention.
Solution Approach 2:
The patent implements a self-service approach where the protective function is provided by a fluid that is introduced and removed as needed during the drilling process itself. The fluid serves the protective function automatically during drilling, eliminating the need for separate filling and removal operations. The system essentially protects itself during the critical drilling operation without requiring additional preparatory or cleanup steps.
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
Prevents damage to internal walls by attenuating laser energy, allows for faster drilling with reduced temperature increase, and facilitates efficient removal of debris and trapped air, enhancing the drilling process efficiency and component integrity.
Implementation Method 1
directing the fluid from the internal cavity and through the at least one hole so as to exit the hollow component via the at least one hole
Data Source
AI summary
A method for forming a hollow component includes injecting a fluid into an internal cavity of the hollow component to achieve a pressure of the fluid within the internal cavity that is greater than an ambient pressure. The method further includes drilling at least one hole through the hollow component from an external surface of the hollow component to the internal cavity by applying a laser beam to the hollow component with a laser generator. The method further includes directing the fluid from the internal cavity and through the at least one hole so as to exit the hollow component via the at least one hole.