Cavity-Back Airfoil Diffusion Bonding for Hollow Titanium Fan Blades
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Solution Overview
Problem
The manufacturing of hollow titanium fan blades for gas turbine engines is challenging due to equipment investment, limited throughput, and yield, with fusion welding causing degradation of ductility and fatigue strength, which are critical for withstanding bird impacts and extended service life.
Innovation Solution
A fixture assembly with a sub-fixture and actuators, including heating elements and sensors, is used to selectively move and bond a cover to a blade body, employing diffusion bonding with controlled temperature and pressure to enhance bonding quality and prevent distortion, reducing the need for complex equipment and processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fusion welding is used to join the cover to the blade body, then the bonding strength is improved, but the ductility and fatigue strength are degraded
Solution Approach 1:
The patent changes the bonding parameters by using diffusion bonding instead of fusion welding, controlling temperature (1000-1600°F), pressure (400-2000 psi), and time (1-24 hours) to achieve strong bonds while preserving the ductility and fatigue strength of the titanium alloy materials
Solution Approach 2:
The patent replaces the mechanical fusion welding system with a thermal-diffusion system, using controlled heat and pressure to enable atomic diffusion across the bond interface, which creates a stronger and more reliable joint without the harmful effects of welding
2Manufacturing precision
If complex diffusion bonding equipment is used to manufacture hollow titanium fan blades, then the bonding quality is improved, but the equipment investment and device complexity increase
Solution Approach 1:
The patent segments the bonding process into controlled stages using a fixture assembly with multiple independent actuators, each controlling a separate bonding zone. This allows precise local control of temperature and pressure without requiring a single complex monolithic bonding chamber
Solution Approach 2:
The fixture assembly serves multiple functions: it positions the cover and blade body, applies localized pressure through actuators, provides heating elements for temperature control, and maintains alignment throughout the bonding process, replacing what would otherwise require multiple separate equipment systems
3Ease of manufacture
If traditional manufacturing processes are used for hollow titanium fan blades, then the equipment investment is reduced, but the production throughput and yield are limited
Solution Approach 1:
The patent performs preliminary actions by pre-positioning the cover and blade body in the fixture assembly before bonding, pre-heating the bonding zones, and pre-adjusting the actuators to the correct pressures. This preparation work is done outside the actual bonding cycle, enabling faster production cycles and higher throughput
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 results in a cost-effective, efficient, and environmentally friendly production of hollow titanium fan blades with improved mechanical properties, reducing surface contamination and capital expenses while increasing production efficiency and bird-strike resistance.
Implementation Method 1
diffusion bonding the periphery of a cavity-back airfoil
Implementation Method 2
heating a sub-fixture located at least partially within the first fixture portion
Implementation Method 3
a multiple of actuators to selectively move the sub-fixture toward the second fixture portion
Data Source
AI summary
A fixture assembly includes a first fixture portion, a second fixture portion that interfaces with the first fixture portion, and a sub-fixture movably mounted to the first fixture portion. A multiple of actuators selectively move the sub-fixture toward the second fixture portion. A method of manufacturing a fan blade includes deploying the sub-fixture from the first fixture portion to effectuate a peripheral diffusion bond to join the blade body and the cover of the fan blade.