Blade Tip Grinding Fixture for Gas Turbine Rotor Positioning
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Solution Overview
Problem
Existing methods for machining compressor or turbine blade tips in gas turbine engines face challenges in accurately controlling radial forces and simulating centrifugal forces, leading to unsatisfactory results due to loose-fitting dovetail joints and high-speed rotor rotation, which is unsafe, inconvenient, and costly.
Innovation Solution
A fixture assembly with disc springs and clamping members that apply balanced axial compressive forces to convert into radial expansion forces, positioning blades relative to the rotor, simulating centrifugal forces without high-speed rotation, using toggle joint devices and resilient materials to ensure accurate and even force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If radial expansion of resilient materials under axial compression forces is used to simulate centrifugal force, then blades can be positioned during machining, but accurate control of quantity, acting points, and even distribution of radial forces becomes difficult
Solution Approach 1:
The fixture tool is divided into multiple independent wedge-shaped elements, each capable of applying radial force to individual blades. This segmentation allows precise control of force acting points and distribution, as each wedge can be independently positioned and adjusted to apply force at specific locations on the blade platforms.
Solution Approach 2:
Each wedge-shaped element is designed with specific geometric properties (angle, width, height) that can be locally adjusted to control the magnitude and distribution of radial forces. The local quality of each wedge element is optimized to apply uniform radial expansion forces across multiple blades, improving force distribution control.
2Manufacturing precision
If rotor assembly is rotated at high speed to create centrifugal force for blade positioning, then blades are positioned within slots, but safety concerns, convenience issues, and manufacturing cost increase
Solution Approach 1:
Instead of rotating the rotor at high speed to generate centrifugal force, the invention inverts the approach by using stationary wedge-shaped elements that apply radial expansion forces directly to the blades. This eliminates the need for high-speed rotation while achieving the same blade positioning effect, thereby removing safety hazards associated with rotating heavy rotor assemblies.
Solution Approach 2:
The invention replaces the dynamic mechanical system of high-speed rotor rotation with a static mechanical system using wedge-shaped elements. The wedges convert axial compression forces into radial expansion forces, substituting the centrifugal force generation method and eliminating the need for high-speed rotation, thus improving safety and reducing manufacturing complexity.
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 solution enables precise radial positioning and machining of blade tips, improving manufacturing accuracy and safety by simulating centrifugal forces without the need for high-speed rotor rotation, thus enhancing the manufacturing process efficiency and reducing costs.
Implementation Method 1
disc springs and clamping members that apply balanced axial compressive forces to convert into radial expansion forces
Implementation Method 2
The first and second positioning members are adapted to transmit a pair of radial forces on the respective first and second portions of each of the blade platforms for radially positioning the blades outwardly against the rotor, thereby simulating a centrifugal force resulting from rotor rotation
Data Source
AI summary
A fixture assembly for securely positioning a plurality of blades loosely assembled on to a rotor of a gas turbine engine in which axial clamping forces are translated to apply radial expansion forces on the blades to simulate a centrifugal force on the blades during engine operation.