Aircraft Turbine Blade Tip Welding With Squeezed Edge Stops
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Solution Overview
Problem
The existing methods for repair welding of one-piece bladed discs in aircraft turbine engines, specifically using Laser Metal Deposition (LMD), face issues with defects such as lack of bonding and collapse at the beginning and end zones of the bead due to the geometry and thickness of the blade tips, leading to unacceptable radiographic indications and thermal or dimensional affects.
Innovation Solution
A method where stops are secured solely by mechanical squeezing on the leading and trailing edges, eliminating the need for pointing and maintaining the stops through mechanical means, allowing for consistent power deposition and avoiding thermal and dimensional issues during the repair welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stops are attached by penetrated welding to ensure they remain in place during repair welding, then the attachment strength is sufficient, but the blade develops Thermally Affected Zones and Deformation Zones that affect the final part metallurgically and dimensionally
Solution Approach 1:
The patent replaces the thermal welding attachment method with a mechanical friction-based attachment method. The stop is pressed against the blade surface with sufficient normal force to create friction that holds the stop in place during repair welding, eliminating the need for penetrated welding and avoiding Thermally Affected Zones while maintaining adequate attachment strength
2Strength
If the power at the beginning and end of the bead is increased to avoid lack of bonding, then bonding is improved, but the blade edges experience excessive penetration and collapse
Solution Approach 1:
The patent introduces a stop as a mechanical intermediary element that physically supports the blade edge at the beginning and end of the repair welding bead. This stop prevents excessive penetration and collapse during welding, allowing consistent power deposition throughout the bead without needing to increase power at the ends, thereby maintaining both bonding strength and blade edge geometry
Solution Approach 2:
The patent changes the welding parameter approach by maintaining constant power throughout the entire bead deposition process rather than dynamically adjusting power at the beginning and end. The mechanical support from the stop enables this parameter simplification while preventing the defects that would normally occur with constant power deposition
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 effectively prevents the collapse of blade edges and excessive penetration, reducing the generation of Thermally Affected Zones and ensuring a strong, high-strength repair weld with minimal deformation, thereby improving the quality and reliability of the repair welding process.
Implementation Method 1
a repair welding of this tip by an additive manufacturing method by powder deposition and fusion, also known as the LMD-p method (acronym of 'Laser Metal Deposition-powder')
Implementation Method 2
powder deposition and fusion
Implementation Method 3
The stops, also known as pointing stops, used so far are based on standard stop geometries... the first and second stops are secured solely by squeezing the first and second stops on the leading and trailing edges
Data Source
AI summary
A method repairs welding of an aircraft turbine engine blade that has a lower surface and an upper surface connected by a leading edge and a trailing edge. The blade further includes a free end referred to as the tip. The method includes the repair welding of the tip and including the steps of: securing a first stop to the leading edge at the tip and a second stop to the trailing edge at the tip, depositing a repair weld bead on the tip, from the first stop to the second stop, and removing the first and second stops. The first and second stops are secured solely by squeezing same on the leading and trailing edges.