Two-Stage Welding Process for Large Turbomachine Rotor Assembly
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Solution Overview
Problem
The existing manufacturing processes for large turbomachine rotors are cost-intensive and inflexible, requiring large and expensive facilities, and face technical difficulties when assembling large rotors vertically, especially in achieving high-quality welds and efficient production.
Innovation Solution
A two-stage welding process is used to assemble and weld disc-shaped elements in a horizontal position, followed by tilting and stress-relief annealing, allowing for the production of larger rotors with smaller production facilities, using TIG welding for initial seam formation and submerged arc welding for filling, and local heat treatment to reduce costs and increase flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If large manufacturing facilities are used to assemble and weld large rotors, then the rotor size can be increased, but the capital investment and production costs increase significantly
Solution Approach 1:
The rotor assembly process is segmented into multiple stages: initial stacking in vertical position, pre-welding in vertical position, tilting to horizontal position, and final welding in horizontal position. This segmentation allows each stage to be performed in a compact facility rather than requiring one large facility for the entire process
Solution Approach 2:
The patent utilizes vertical stacking of discs to achieve the required rotor length, then transitions to horizontal positioning for welding. By using the vertical dimension for accumulation and horizontal dimension for welding operations, the facility footprint is minimized while still accommodating large rotor dimensions
2Device complexity
If vertical assembly and welding is used for large rotors, then the rotor can be assembled in a compact facility, but high-quality welds become difficult to achieve and technical difficulties arise
Solution Approach 1:
The welding process is divided into two distinct stages: pre-welding performed in vertical position using TIG welding for root seam formation, and final welding performed in horizontal position using submerged arc welding for groove filling. This segmentation allows each welding stage to be optimized for its specific orientation and quality requirements
Solution Approach 2:
Instead of completing all welding operations in the initial vertical position, the patent inverts the approach by performing final critical welding operations after tilting to horizontal position. This reversal enables the use of horizontal positioning for the most quality-critical welding steps while maintaining compact facility dimensions
3Device complexity
If all welding operations are performed in a common heater, then the process is simplified, but the heating box must be continuously expanded to accommodate increasing rotor length
Solution Approach 1:
The heating requirement is segmented into two phases: initial preheating in vertical position for a limited number of discs, and subsequent heating after tilting to horizontal position. This allows the heating apparatus to be sized for the initial stack only, avoiding the need for continuous expansion
Solution Approach 2:
The necessary preheating and pre-welding operations are completed in advance while the rotor stack is in vertical position, before the rotor is tilted to horizontal position for final welding. This preliminary action ensures that the heating apparatus only needs to accommodate the initial stack dimensions
4Manufacturing precision
If TIG welding is used for root seam formation, then precise seam formation is achieved, but the production speed is limited
Solution Approach 1:
The welding process is segmented into two distinct operations: TIG welding for root seam formation requiring precision but performed on a limited scope, and submerged arc welding for groove filling performed on the remaining larger volume. This segmentation allows each process to be optimized for its specific function
Solution Approach 2:
Instead of using TIG welding for the entire weld volume, the patent applies TIG welding partially only for root seam formation, then uses the faster submerged arc welding process for the remaining groove filling, achieving both precision where needed and speed where possible
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 method enables the production of larger rotors with reduced capital investment and increased labor productivity, allowing for more flexible production and efficient quality control, as smaller production plants can accommodate the process, and local heat treatment minimizes the need for large heating chambers.
Implementation Method 1
the panes being pre-turned in a horizontal position, then stacked one on top of the other in a vertical direction up to a predetermined size, only the first welding process being carried out while a longitudinal axis of the assembled panes is still in vertical storage
Implementation Method 2
CH 595 011 describes the use of the TIG welding process to join one pane to the next in a horizontal direction, and performing a submerged arc welding process to fill up the remaining grooves
Implementation Method 3
Finally, after all disks have been successively welded on, the rotor is subjected to a stress-relief annealing process
Implementation Method 4
and then to an ultrasonic test
Data Source
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Figure 2
Figure 3
AI summary
The invention relates to a method for producing a rotor (2) made by welding together disc and/or drum-shaped elements, particularly discs, wherein said discs are assembled in sequence along a longitudinal axis (A) by means of a device and welded in a two-stage welding process. The discs are stacked axially in the vertical direction during assembly. A first welding process takes place in a vertical orientation of the stacked discs, followed by a second welding process in a horizontal orientation of the stacked discs.