Electrode for Cooling Channel Diffusion Portion
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Solution Overview
Problem
Existing methods for forming cooling channels in turbomachine blades are lengthy and expensive, particularly due to the complexity and cost of electroerosion techniques used for both hole and diffusion portion creation.
Innovation Solution
A method involving two distinct steps: laser piercing for the hole and electroerosion for the diffusion portion, using simpler and less expensive electrodes, with a cone-shaped electrode for the diffusion portion to avoid sharp angles and ensure effective air diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electroerosion is used to form both the hole and diffusion portion in a single step, then the cooling channel can be formed in one operation, but the process is lengthy and expensive due to the complexity of the electrode required
Solution Approach 1:
The cooling channel formation process is divided into two distinct steps: first forming the hole, then forming the diffusion portion. This segmentation allows each step to use a simpler electrode geometry (cylindrical for hole, conical for diffusion portion) rather than requiring a single complex electrode with both hole and diffusion portion geometries, thereby reducing electrode manufacturing complexity and cost while improving overall productivity
Solution Approach 2:
A cylindrical electrode is used as an intermediary tool to first create the hole, which then serves as the starting point for the second electrode (conical) to form the diffusion portion. This intermediary approach allows the use of simpler, standardized electrode geometries rather than requiring a single complex-shaped electrode, resolving the contradiction between process efficiency and electrode complexity
2Ease of manufacture
If a sharp angle is created at the bottom of the diffusion portion, then the electrode can be simpler in shape, but sharp angles constitute starter zones for cracks reducing reliability
Solution Approach 1:
The electrode tip is designed with a conical geometry that presents a flat surface, creating a rounded or flattened bottom at the diffusion portion rather than a sharp angle. This curvature principle eliminates stress concentration points that would initiate cracks, maintaining reliability while keeping the electrode geometry relatively simple through the use of standard conical shapes with modified tips
3Productivity
If laser piercing is used instead of electroerosion for the hole, then the process is much faster and less expensive, but the diffusion portion still requires electroerosion
Solution Approach 1:
Different manufacturing processes are applied to different portions of the cooling channel: laser piercing is used locally for the hole formation where speed and cost-effectiveness are critical, while electroerosion is used locally for the diffusion portion where precise geometric control and rounded bottom formation are required. This localized application of appropriate processes optimizes both productivity and quality without requiring the entire process to use a single method
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 significantly reduces the time and cost of forming cooling channels while preventing crack formation and ensuring efficient air guidance and spreading for effective cooling of the outside surface.
Implementation Method 1
to pierce the wall by laser, generally only a few tenths of a second are required
Implementation Method 2
if it is desired to perform the piercing and the diffusion portion by electroerosion
Data Source
AI summary
A wall in which there is formed at least one cooling channel, said wall being cooled by cool air flowing in the channel, the channel comprising a hole and a diffusion portion, the hole opening out at one end into the inside surface of the wall, and at its other end into the diffusion portion where it forms an orifice, the diffusion portion flaring around said orifice and opening out into the outside surface of the wall, the diffusion portion having a bottom whose front end is substantially plane, sloping, and extending in front of the orifice, and also having a margin extending behind, round the sides, and in front of the orifice, said margin joining the sides of the front end. A method and an electrode for making such a cooling channel. A turbomachine blade presenting such a wall.