Modular Rotor Circumference Machining for In-Situ Turbine Repair
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Solution Overview
Problem
Existing machining apparatuses for gas turbine rotors are large, bulky, and costly, requiring extensive downtime and transportation challenges when attempting to machine the outer circumference, leading to high operational costs and inefficiencies.
Innovation Solution
A modular machining apparatus comprising separate carriages connected by a lashing strap with a tensioning device, equipped with floating wheels and a tool carrier, allowing flexible arrangement and tensioning around the rotor for in-situ machining, with adjustable tension and tool exchange capabilities, and featuring low weight and compact transport dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional machining apparatus is used to machine the rotor outer circumference, then the machining can be performed, but the apparatus is large and bulky requiring extensive transportation and assembly time with high costs
Solution Approach 1:
The machining apparatus is divided into multiple separate carriages (at least three carriages) that can be independently transported and assembled around the rotor. Each carriage contains necessary machining components, allowing the system to be broken down into manageable units that are easier to transport and assemble compared to a single large apparatus.
Solution Approach 2:
The carriages are designed with universal functionality to perform machining operations on rotors of different diameters. The modular design allows the same carriage components to be used across various rotor sizes, reducing the need for multiple specialized apparatuses and simplifying transportation requirements.
2Productivity
If the rotor is uninstalled from the turbine for machining, then the machining can be performed, but the gas turbine experiences long downtime entailing high costs
Solution Approach 1:
The machining apparatus is pre-assembled around the rotor while the rotor is still installed in the turbine. The carriages are positioned and secured to the rotor surface before machining operations begin, eliminating the need to uninstall the rotor for setup. This preliminary positioning allows machining to start immediately without turbine shutdown delays.
Solution Approach 2:
The machining system is designed to be self-contained and self-supported during operation. The carriages are self-propelled or motor-driven along the rotor surface, and the machining tools are automatically controlled, allowing the system to perform machining operations independently without requiring rotor removal or extensive external support infrastructure.
3Loss of time
If a transportable machining apparatus is brought to the installation site, then downtime can be shortened, but very high transportation and assembly costs are involved
Solution Approach 1:
By segmenting the apparatus into multiple carriages, each carriage can be transported separately using standard equipment rather than requiring specialized heavy-lift transportation. The carriages are assembled around the rotor at the installation site, reducing transportation costs while maintaining the ability to perform machining without rotor removal.
Solution Approach 2:
The lashing strap system uses flexible tensioning elements to secure the carriages to the rotor surface. This flexible connection method allows the apparatus to adapt to the rotor's curvature and size variations without requiring rigid, heavy structural components, thereby reducing overall apparatus weight and transportation costs.
4Adaptability or versatility
If the number of carriages is increased to adapt to larger rotor diameters, then the adaptability improves, but the apparatus weight increases
Solution Approach 1:
The apparatus uses multiple lightweight carriages instead of a single heavy structure. Each carriage is independently sized and weighted, allowing the total number of carriages to be adjusted based on rotor diameter requirements. This segmentation enables scaling to larger rotors by simply adding more carriages rather than increasing the weight of individual components.
Solution Approach 2:
The system allows dynamic adjustment of the number of carriages and their spacing based on the rotor diameter being machined. For larger rotors, more carriages are used with increased spacing, while for smaller rotors, fewer carriages are used with closer spacing. This parameter adjustment maintains adaptability across different rotor sizes without permanently increasing apparatus weight.
Data Source
AI summary
A machining apparatus which is designed for machining the outer circumference of a rotor, in particular of a gas-turbine or steam-turbine rotor, includes a plurality of separate carriages, at least one tensioning strap, wherein the carriages can be connected to one another to create an annular arrangement, and also having a tensioning device, in particular in the form of a pressure ratchet, which is designed for tensioning the tensioning strap. The carriages are each provided with preferably floating-mounted wheels, which are oriented in a direction of travel, and wherein at least one carriage has a tool carrier for accommodating a machining tool and driving it by motor. A method for machining the outer circumference of a rotor by using such a machining apparatus is provided.