Segmented Turbomachine Exhaust Casing Assembly for Geometric Quality
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Solution Overview
Problem
Current manufacturing methods for large diameter turbomachine exhaust casings are complex, expensive, and prone to geometric quality issues due to the difficulty of producing a single cast hub, especially for diameters around 1.5 meters.
Innovation Solution
The method involves producing sectored casing components, including hub and ferrule sectors linked by arms, which are assembled and welded circumferentially to form a casing, eliminating the need for welding arms directly to a large hub and reducing geometric defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single cast hub is produced for large diameter casings, then the casing can be manufactured as a complete structure, but the manufacturing process becomes complex and expensive with increased risk of geometric defects
Solution Approach 1:
The hub is divided into multiple hub sectors that are cast separately and then assembled around a mandrel. This segmentation allows each sector to be manufactured with simpler processes and lower risk of geometric defects, while the final assembled structure achieves the required large diameter and geometric quality through precise welding of the sectors together.
2Reliability
If arms are welded directly to a large hub, then the casing structure is completed, but the welding process becomes long and laborious with increased risk of welding defects
Solution Approach 1:
The arms are pre-attached to the hub sectors during the casting process itself, creating integrated hub-sector-arm assemblies before the final circumferential welding. This preliminary action eliminates the need for separate, time-consuming welding operations to attach arms to the completed hub, significantly reducing total welding time and the risk of welding defects.
3Ease of manufacture
If a large diameter hub is produced as one piece, then the casing can be manufactured, but the cost and complexity of production increase significantly
Solution Approach 1:
The hub is segmented into multiple smaller hub sectors that can be manufactured using standard casting processes available for smaller components. These sectors are then assembled circumferentially around a mandrel and welded together, achieving the large diameter requirement without requiring complex single-piece casting equipment or processes.
Solution Approach 2:
A mandrel is used as an intermediary tool to support and position the hub sectors during assembly and welding. The mandrel provides a reference surface for positioning the sectors and ensures proper geometric relationships, enabling the complex assembly process to be executed with standard manufacturing capabilities.
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 approach simplifies the manufacturing process, reduces labor and risk of welding errors, and allows for the production of larger diameter casings with improved geometric quality.
Implementation Method 1
The longitudinal edges facing the hub sectors are then welded, preferably by electron beam (EB).
Data Source
AI summary
A method for manufacturing a casing, for example, an exhaust casing, for a turbomachine. The method generally includes: (a) producing casing sectors, each casing sector having a hub sector, a ferrule sector, and at least one arm linking the hub and ferrule sectors, (b) arranging the casing sectors adjacently and circumferentially, such that each hub sector has longitudinal edges facing longitudinal edges of adjacent hub sectors, (c) welding the longitudinal edges facing the hub sectors, and (d) adding and welding at least a second part of the ferrule to the casing sectors.