Steam Turbine Rotor Blade Axial Fixation via Segmented Key
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Solution Overview
Problem
Existing steam turbine rotor blade fixation methods, such as those using plastic deformation of keys, are cumbersome and may not provide sufficient fixation, leading to potential axial movement of rotor blades due to steam pressure.
Innovation Solution
A rotor blade fixation system where a key is inserted into a circumferential groove and key accommodating groove, with a platform and blade body configuration that allows for secure attachment without the need for plastic deformation, ensuring reliable restraint against axial movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a key is plastically deformed to fix the rotor blade, then the rotor blade can be restrained in the axial direction, but the attachment process becomes troublesome and complex
Solution Approach 1:
The key is divided into two functional parts: a insertion portion that fits into the axial groove for positioning, and a protruding portion that extends radially outward to be engaged by the rotor blade's platform groove. This segmentation eliminates the need for plastic deformation while maintaining reliable axial restraint.
Solution Approach 2:
The key acts as an intermediary component between the rotor disk and the rotor blade platform. By providing a simple insertion-engagement mechanism through the axial and radial grooves, it mediates the connection without requiring complex deformation processes.
2Reliability
If a key is plastically deformed to fix the rotor blade, then axial movement can be restrained, but sufficient fixation may not be achieved
Solution Approach 1:
The key's divided structure with insertion and protruding portions ensures precise positioning through the axial groove and reliable engagement through the radial groove, achieving sufficient fixation without depending on the precision of plastic deformation.
Solution Approach 2:
The key automatically achieves proper positioning and fixation through its geometric design. The insertion portion self-aligns in the axial groove, and the protruding portion self-engages with the platform groove, eliminating the need for controlled plastic deformation processes.
3Ease of manufacture
If a key insertion method without plastic deformation is used, then the attachment process becomes easier, but the rotor blade may not be sufficiently restrained
Solution Approach 1:
The key's two-part structure provides both ease of insertion and reliable restraint. The simple insertion portion facilitates easy attachment, while the engaged protruding portion ensures sufficient axial restraint through the groove geometry.
Solution Approach 2:
The key is pre-configured with the protruding portion designed to engage the platform groove. This preliminary design ensures that upon insertion, the engagement occurs automatically, providing both ease of attachment and reliable restraint without requiring post-insertion deformation.
Data Source
AI summary
A rotor of a steam turbine includes a plurality of rotor blades attached to a disk portion and a key configured to restrict movement of each of the plurality of rotor blades in an axial direction. The disk portion includes a blade embedding groove and a circumferential groove. The plurality of rotor blades include a first rotor blade and a second rotor blade adjacent to the first rotor blade on one side in a circumferential direction. A platform of the first rotor blade includes an access groove communicating with the circumferential groove, and a platform of the second rotor blade includes a second side surface facing a first side surface in the circumferential direction and a key accommodating groove communicating with the access groove in the circumferential direction. A key is arranged in the circumferential groove and the key accommodating groove.