Turbine Rotor Blade Fixing Structure With Mechanical Latch
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Solution Overview
Problem
Conventional fixing structures for turbine rotor blades in steam turbines require complex welding and chipping processes, making assembly and disassembly cumbersome due to the need for preheating and continuous welded portions, which complicates the process and increases working time.
Innovation Solution
A fixing structure that includes a T-shaped fixing groove with inner and outer peripheral latches and a center latch, where the inner peripheral latch has a bent portion to secure the blade implantation portion without welding, facilitating assembly and disassembly by eliminating the need for continuous welded portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding is used to fix the latch member in the fixing groove, then the strength and reliability of the connection is improved, but the complexity of the manufacturing process and the time required for assembly and disassembly increases
Solution Approach 1:
The patent replaces the welding process (thermal/chemical connection) with a mechanical interlocking system. The latch member includes engagement protrusions that fit into engagement grooves on the rotor blade, creating a secure mechanical connection without requiring welding. This substitution eliminates the complex welding and chipping processes while maintaining connection reliability through precise mechanical fitting.
2Strength
If continuous welded portions are used to secure the locking blade, then the structural integrity is improved, but the working time and operational efficiency deteriorate due to preheating and chipping requirements
Solution Approach 1:
The latch member is divided into multiple independent engagement protrusions distributed along its length, rather than using continuous welded portions. Each engagement protrusion independently secures a corresponding engagement groove, providing distributed structural integrity. This segmentation allows for faster assembly and disassembly operations while maintaining the overall strength of the connection through multiple discrete attachment points.
Solution Approach 2:
The engagement protrusions are designed with elastic deformation capability, allowing them to flex during assembly and disassembly operations. This dynamic characteristic enables the protrusions to be inserted and engaged without excessive force, and to be removed when needed, significantly reducing the working time compared to rigid welded connections that require preheating and chipping.
3Ease of operation
If the latch member uses a simple insertion structure, then the ease of assembly is improved, but the reliability of securing the rotor blade against centrifugal force deteriorates
Solution Approach 1:
The engagement protrusions and grooves are designed with asymmetric geometries that provide directional insertion ease while ensuring secure retention. The protrusions have tapered leading edges that facilitate insertion in the assembly direction, while the engagement grooves have corresponding asymmetric profiles that lock the protrusions in place once inserted. This asymmetric design maintains simple assembly operations while preventing reverse extraction, thereby ensuring blade securing reliability under centrifugal force.
Solution Approach 2:
The engagement surfaces of the protrusions and grooves incorporate curved and rounded features rather than sharp angles. These curved surfaces distribute contact stresses more evenly during insertion and engagement, facilitating easier assembly while maintaining secure mechanical interlocking. The curvature also helps in stress distribution under centrifugal loading, enhancing the reliability of the blade securing without complicating the assembly process.
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 solution simplifies the assembly process by eliminating the need for welding and reduces disassembly complexity by allowing easy removal of the locking blade through chipping or unbending the bent portion, thereby reducing working time and improving operational efficiency.
Implementation Method 1
a bent portion provided at an end portion on a downstream side in the axial direction in the inner peripheral latch or the outer peripheral latch, the bent portion being bent to the center latch side to fix the blade implantation portion of the locking blade in the blade groove
Data Source
AI summary
A fixing structure for a rotor blade of an embodiment includes: a fixing groove penetrating blade implantation portions and a rotor wheel in a circumferential direction; a locking blade lastly fitted into a blade groove; and a latch member inserted from an axial direction into the fixing groove formed in the blade implantation portion of the locking blade and the rotor wheel forming the blade groove into which the blade implantation portion of the locking blade is fitted. The latch member includes: an inner peripheral latch disposed on a radially inner side; an outer peripheral latch disposed on a radially outer side; a center latch fitted between the inner peripheral latch and the outer peripheral latch, and a bent portion provided at an end portion on a downstream side in the axial direction of the inner peripheral latch, the bent portion being bent to fix the locking blade.