Patch Ring Repair for Turbomachine Rabbet Joint Wear
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Solution Overview
Problem
Turbomachine shafts, particularly compressor and turbine shafts, experience wear and tear leading to damage and reduced operational life, with existing repair methods like post-operational machining affecting the contact interference between rabbet joints, necessitating improved methods for repairing rabbet joints.
Innovation Solution
A patch ring is mounted between the rabbet joints of the compressor and turbine shafts, featuring a main body with radially extending arms that provide contact surfaces and alignment, reducing axial movement and accommodating thermal expansion, thereby maintaining design-intended interference and extending shaft life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If post-operational machining is performed on the rabbet joint contact surfaces, then wear damage is removed and shafts can be reused, but the design-specified interference between shafts deteriorates and shaft life is reduced
Solution Approach 1:
A removable patch ring is introduced as an intermediary component between the compressor shaft and turbine shaft rabbet joints. The patch ring includes a body portion that fits into the rabbet joint cavity and contact surfaces that interface with both shafts, serving as a mediator that restores the designed interference fit without requiring precision machining of the original shaft surfaces.
Solution Approach 2:
The repair solution segments the rabbet joint contact surface into two parts: the original shaft surface and the added patch ring surface. This segmentation allows the patch ring to be independently manufactured and installed to restore the precise interference fit, while the original shafts can be reused without requiring high-precision re-machining.
2Ease of repair
If the rabbet joint is machined multiple times over service intervals, then wear is repeatedly removed, but the contact interference continuously deteriorates
Solution Approach 1:
The patch ring serves as a replaceable intermediary that absorbs the wear and dimensional changes that would otherwise accumulate in the shaft rabbet joints. By installing a new or refurbished patch ring, the original shafts are protected from further machining, preserving their original dimensions and ensuring reliable contact interference throughout multiple service intervals.
Solution Approach 2:
The patch ring is designed as a consumable component with a limited service life. Instead of repeatedly machining the expensive and critical shaft components, the relatively inexpensive patch ring can be replaced when worn, ensuring the permanent preservation of shaft dimensions and contact interference reliability.
3Duration of action of stationary object
If the shaft components are designed for long operational life, then durability is improved, but wear at sensitive locations accelerates and limits actual service life
Solution Approach 1:
The wear-prone contact surfaces are extracted from the permanent shaft components and transferred to the removable patch ring. This allows the shafts to maintain their long design life while the patch ring absorbs the wear damage at the rabbet joint contact surfaces, which can be replaced when worn.
Solution Approach 2:
The patch ring is designed to be discarded after a certain service life when wear accumulates. By discarding the worn patch ring and installing a new one, the valuable shaft components are recovered and protected from wear, allowing them to continue serving for their full design life or beyond.
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 patch ring effectively maintains the required interference between the compressor and turbine shafts, reducing wear and extending the operational life of turbomachine components by stabilizing the rabbet joints and allowing for thermal expansion during operation.
Implementation Method 1
allowing for thermal expansion during operation
Data Source
AI summary
Shaft assemblies, turbomachines, and methods of servicing a turbomachine are provided. A shaft assembly includes a first shaft having a first rabbet annularly defined therein. The first rabbet includes a first axially extending face and a first radially extending face. A second shaft coupled to the first shaft. The second shaft includes a second rabbet annularly defined therein and positioned opposite the first rabbet. The second rabbet includes a second axially extending face and a second radially extending face. A patch ring is mounted between the first rabbet and the second rabbet. The patch ring includes a main body positioned between and in contact with the first axially extending face and the second axially extending face. A first arm extends radially outward from the main body, and a second arm extends radially inward from the main body.