Variable Guide Vane Repair via Laser Cladding
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Solution Overview
Problem
Existing methods for repairing variable guide vanes in gas turbines, such as high-velocity oxy-fuel spraying and plasma spraying, result in reduced wear resistance and increased frequency of repair due to high heat input and incomplete bonding, leading to rapid wear and distortion.
Innovation Solution
Laser build-up welding is used to repair variable guide vanes with a focus on minimal heat input and targeted application of wear-resistant materials like stellite, nitrides, and carbides, allowing for localized repair without machining or roughening, and simultaneous processing of multiple vanes to reduce heat input and process time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high-velocity oxygen fuel (HVOF) spraying or plasma spraying is used to repair variable guide vanes, then the repair process is simple and can be applied to damaged areas, but the wear resistance of the repaired areas is reduced and they wear out even faster
Solution Approach 1:
The patent changes the fundamental parameters of the repair process by switching from thermal spray methods (HVOF, plasma) to laser beam cladding. This involves changing the energy source, heating mechanism, and material deposition method. The laser process parameters (power, speed, focus) are optimized to achieve complete metallurgical bonding without the drawbacks of spray methods, thereby improving wear resistance while maintaining repair feasibility
Solution Approach 2:
The patent replaces the mechanical spray deposition process with a laser-based melting and fusion process. Instead of mechanically projecting particles onto the surface, the laser beam melts both the base material and filler material to create a metallurgically bonded cladding layer. This substitution of the fundamental repair mechanism eliminates the poor bonding and rapid wear associated with spray methods
2Area of stationary object
If the entire outer platform or pin notch area is rebuilt using plasma spray over the full circumference, then complete coverage is achieved, but the bond strength between sprayed layer and base material is low and machining/roughening is required
Solution Approach 1:
The patent changes the bonding mechanism parameter from mechanical adhesion (spray) to metallurgical fusion (laser cladding). By controlling laser power, travel speed, and material feed rate, the process achieves complete fusion between filler and base material, creating a homogeneous structure with superior bond strength that eliminates the need for extensive surface preparation
Solution Approach 2:
The patent substitutes the mechanical spray deposition system with a laser beam cladding system that melts and fuses materials. This replacement transforms the bonding mechanism from weak mechanical adhesion to strong metallurgical fusion, achieving complete coverage with superior bond strength without requiring machining or roughening of the base surface
3Quantity of substance
If laser beam cladding is used with high heat input, then material can be deposited effectively, but the variable vane experiences distortion and warpage
Solution Approach 1:
The patent employs periodic or pulsed laser action with controlled duty cycles to deposit material in multiple passes. By using lower power settings with intermittent heating and allowing cooling intervals between passes, the process accumulates material deposition over time while minimizing thermal distortion. This periodic action enables effective cladding without excessive heat input that would cause warpage
Solution Approach 2:
The patent segments the material deposition process into multiple thin layers deposited in sequential passes rather than attempting to deposit large amounts of material in a single pass. Each layer is deposited with controlled, lower heat input, and the cumulative effect achieves the required material quantity while minimizing thermal distortion at each stage. This segmentation of the deposition process prevents excessive heat accumulation
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
The method enhances wear resistance and service life of variable guide vanes by providing a strong metallurgical bond and reducing warpage, making the repair process more economical and less frequent, while maintaining high-quality machining standards.
Implementation Method 1
the area affected by wear is rebuilt by laser beam cladding with filler material
Implementation Method 2
a metallurgical bond is formed between the variable guide vane and the filler material
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a method for repairing a variable guide vane (1) for a gas turbine, wherein, in the course of the method, additional material is applied to the variable guide vane (1) by material application, wherein the material application takes place by laser beam build-up welding.