Steam Turbine Stage Sectors With EDM Hollow Blade Cavities
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Solution Overview
Problem
The existing method for manufacturing a steam turbine stage with hollow blades requires manual welding, leading to increased assembly time and costs due to the need for precise tolerances.
Innovation Solution
A method involving milling a block of material to create sectors with blades, machining openings and cavities using wire electric discharge machining, and assembling these sectors without manual welding, reducing the need for manual intervention and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual welding is used to attach blades to rings with strict tolerances, then manufacturing precision is improved, but assembly time and costs increase
Solution Approach 1:
The turbine stage is divided into modular sectors, each comprising multiple blades integrated with a portion of the ring structure. This segmentation allows parallel machining of multiple blade-ring assemblies simultaneously, reducing overall assembly time while maintaining precision through standardized modular interfaces
Solution Approach 2:
Traditional manual welding operations are replaced with automated machining processes. The sector is machined as an integrated component where blades are directly formed from the ring material through milling operations, eliminating the need for manual welding while achieving tighter tolerances through CNC control
2Manufacturing precision
If manual welding is performed within strict tolerances, then manufacturing precision is improved, but production costs increase
Solution Approach 1:
The blade and ring components are merged into a single integrated sector structure. The blade roots are directly formed as part of the ring material through machining operations, eliminating separate welding operations. This integration reduces both labor costs and material costs associated with welding consumables and post-weld treatment
Solution Approach 2:
Manual welding operations are replaced with automated CNC machining processes. The sector is machined from a blank material using computer-controlled milling operations, which reduce labor costs while achieving superior precision. The automated process eliminates skilled welding labor requirements and reduces overhead costs associated with quality inspection and rework
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 minimizes manual intervention and reduces assembly time and costs by eliminating the need for manual welding, while maintaining the functionality of hollow blades to manage condensation in steam turbines.
Implementation Method 1
The step of machining the cavity is performed by wire electric discharge machining
Data Source
Figure 1
Figure 2~2b
Figure 2c
AI summary
A method for manufacturing a stage (1) of a steam turbine comprising the steps of milling a block of material to define a sector (2) having a plurality of blades (6), each blade (6) having an external surface (7); machining an opening (8) in the external surface (7) of at least one of the blades (6); machining a cavity (9) in fluid communication with the opening (8); the step of machining the cavity (9) being performed by wire electric discharge machining.