Gas Turbine Rotor Shaft Cap Machining Precision
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Solution Overview
Problem
Conventional gas turbine rotor shaft manufacturing processes face challenges in accurately machining curvic teeth due to the rotor shaft's physical dimensions, leading to potential inaccuracies and increased costs, with existing solutions not adequately addressing the need for improved balancing and reduced vibrations.
Innovation Solution
A rotor shaft assembly comprising a separately-formed rotor shaft cap with a disk-shaped body and annular jaws, allowing for precise machining and assembly with a rotor shaft, utilizing apertures and pins for secure fitting, and potentially heat-treated for enhanced durability, which can be shrink-fitted to ensure accurate rotational coupling and reduced runout values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If curvic teeth are machined into the rotor shaft towards the end of the manufacturing process, then the rotor shaft can be assembled, but the machining accuracy of the curvic teeth deteriorates due to the rotor shaft's physical dimensions and previous manufacturing stages
Solution Approach 1:
The rotor shaft is divided into two separate components: the main rotor shaft body and a separate cap assembly. The cap assembly, which contains the curvic teeth, is manufactured independently with high precision, then attached to the rotor shaft. This segmentation allows the curvic teeth to be machined at a smaller scale with better accuracy, avoiding the dimensional constraints of the full rotor shaft.
Solution Approach 2:
The cap assembly is manufactured and prepared in advance as a separate component with pre-machined curvic teeth. This preliminary creation of the cap assembly allows for optimized machining processes specific to the smaller component, improving tooth accuracy before final assembly with the rotor shaft.
2Manufacturing precision
If the rotor shaft undergoes numerous earlier manufacturing stages to achieve its general final shape, then the rotor shaft reaches its required dimensions, but the physical dimensions make it difficult to machine the curvic teeth at the desired accuracy
Solution Approach 1:
By separating the rotor shaft into a main body and a cap assembly, the invention isolates the curvic teeth machining to a smaller component. The cap assembly's smaller dimensions allow for precise machining that would be difficult on the full-length rotor shaft, while the main shaft retains its required overall dimensions.
3Ease of repair
If any mistake occurs when machining the curvic teeth, then the curvic teeth can be re-machined, but the expended work and cost are lost
Solution Approach 1:
The separation of the cap assembly from the main rotor shaft allows the cap to be removed and re-machined independently if errors occur. This modular approach enables rework of the curvic teeth without affecting the entire rotor shaft, reducing the scope of potential losses.
Solution Approach 2:
The cap assembly is prepared as a separate, removable component with the curvic teeth machined in advance. This preliminary preparation allows for easier inspection and rework if mistakes are found, as the cap can be detached and re-machined without compromising the main shaft.
4Manufacturing precision
If the rotor shaft is machined to a high degree of precision for accurate balancing, then the rotor operates satisfactorily, but the curvic teeth machining becomes more difficult due to the high precision requirements
Solution Approach 1:
The invention segments the high-precision balancing requirements from the curvic teeth machining. The main rotor shaft is machined to high precision for balancing, while the cap assembly with curvic teeth is a separate component that can be machined with appropriate precision for its function, avoiding the conflict between overall balancing precision and teeth machining ease.
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 higher accuracy in machining the annular jaw, reduces manufacturing costs, and improves balancing and rotational coupling, achieving axial and radial runout values of 25µm or less, thereby enhancing the operational efficiency and reducing vibrations in gas turbines.
Implementation Method 1
the rotor shaft cap (300) is shrink-fitted to the rotor shaft (200)
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A rotor shaft cap (300) for a gas turbine, comprising: a disk-shaped body (310) defining: a first axial face (312), a second axial face (314), and an outer radial face (316), the disk-shaped body (310) comprising: a first annular jaw (330) provided on the first axial face (312), the first annular jaw (330) comprising a plurality of teeth (332) projecting from the first axial face (312); a plurality of apertures (340) defined by the disk-shaped body (310), each aperture (342, 344, 346) of the plurality of apertures (340) extending through the disk-shaped body (310) along an axial direction (30).