Cavity-Back Titanium Fan Blade Welding for Low Residual Stress

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Solution Overview

Problem

The production of hollow titanium fan blades for gas turbine engines is time-consuming, complex, and expensive, requiring costly protective environments and equipment, while existing welding methods can introduce residual stress and distortion.

Innovation Solution

High energy beam welding, such as laser or electron beam welding, is used to attach a cover to the ribs of a twisted cavity-back fan blade, minimizing weld depth and heat input, reducing residual stress and distortion, and incorporating braze material or grooves to lower stress concentrations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional welding methods are used to attach cover to ribs, then structural integrity is achieved, but residual stress and distortion increase

Engineering Contradiction:
Improvestructural integrityVSAvoidresidual stress
Core Design Contradiction:
StrengthVSStress or pressure

Solution Approach 1:

The patent applies high energy beam welding (laser or electron beam) which fundamentally changes the welding parameters compared to traditional methods. This includes using concentrated energy beams with precise control over heat input, weld depth, and processing speed, thereby achieving structural integrity while minimizing residual stress and distortion through optimized energy distribution and reduced thermal affect zone

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If hollow titanium fan blade production uses protective environment and equipment, then manufacturing precision is maintained, but production costs increase

Engineering Contradiction:
Improvemanufacturing precisionVSAvoidproduction costs
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent utilizes the inherent capability of high energy beam welding to perform in controlled environments, where the concentrated beam creates a protective atmosphere around the weld zone, reducing the need for extensive external protective equipment and expensive facility requirements while maintaining manufacturing precision through the beam's natural shielding effect

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The patent replaces traditional mechanical welding systems with high energy beam welding, substituting mechanical contact and protection methods with energy field-based welding that requires minimal physical protective infrastructure, thereby reducing equipment costs and simplifying manufacturing processes while maintaining precision

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Stress or pressure

If high energy beam welding is used to minimize weld depth and heat input, then residual stress and distortion are reduced, but welding process complexity increases

Engineering Contradiction:
ImprovedistortionVSAvoidwelding process complexity
Core Design Contradiction:
Stress or pressureVSDevice complexity

Solution Approach 1:

The patent leverages the versatility of high energy beam welding technology that can be applied to various titanium fan blade configurations and geometries using the same fundamental process, reducing the need for multiple specialized welding systems and simplifying overall process complexity while maintaining minimal distortion across different applications

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 method increases structural integrity and fatigue life, reduces production costs and environmental constraints, and enhances manufacturing consistency and efficiency.

Implementation Method 1

High energy beam welding, such as laser or electron beam welding, is used to attach a cover to the ribs

Methodology Applied
Scientific EffectLaser beam welding: Laser Beam Welding

Implementation Method 2

High energy beam welding, such as laser or electron beam welding, is used to attach a cover to the ribs

Methodology Applied
Scientific EffectElectron beam welding: Welding

Implementation Method 3

incorporating braze material or grooves to lower stress concentrations

Methodology Applied
Scientific EffectBrazing: Brazing

Data Source

PatentEP4170131B1Power beam welded cavity-back titanium hollow fan blade
Publication Date: 2024.06.05 RTX CORP
  • EP4170131B1 patent drawingFigure 1
  • EP4170131B1 patent drawingFigure 2A
  • EP4170131B1 patent drawingFigure 2B

AI summary

An airfoil including an airfoil body (112), a recessed portion (124) of a first depth in a first side (118) of the airfoil body (112), the recessed portion (124) including a plurality of pockets (126) of a second depth located within the recessed portion (124) and ribs (128) of the first depth located between the pockets (126), a cover configured to fit into the recessed portion (124) such that an interior surface of the cover engages the ribs (128) and an exterior surface of the cover is about flush with an exterior surface (122) of the first side (118) of the airfoil body (112), and a high energy beam weld configuration extending through the cover and into the ribs (128) and positioned to attach the cover to the ribs (128).