Turbine Rotor Weight Entry Port With Rounded Crack-Resistant Geometry
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Solution Overview
Problem
The existing method of forming balancing weight entry ports in turbine rotors through milling can result in damage such as cracking due to the creation of circumferentially extending peaks and sharp corners, which are difficult to repair without further damaging the rotor.
Innovation Solution
A tool and method involving motorized machining with a clamp system and radial positioning system to create a balancing weight entry port with rounded corners, extending farther into the rotor body than the slot, to prevent damage and facilitate the introduction of balancing weights while avoiding sharp edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If milling is used to form the balancing weight entry port, then the port can be created to allow weight introduction, but circumferentially extending peaks and sharp corners are left that can initiate cracking
Solution Approach 1:
The patent applies curvature by forming rounded corners and circumferentially extending surfaces at the bottom of the entry port sidewalls instead of leaving sharp corners. This is achieved through specialized milling tools or multi-step machining processes that round the corners and create smooth transitions, eliminating stress concentration points that would initiate cracks while maintaining the port's functionality for weight introduction.
2Ease of operation
If retaining members are removed to form the entry port, then weights can be introduced circumferentially, but the structural integrity is compromised and damage can occur
Solution Approach 1:
The patent applies preliminary action by pre-forming the entry port with rounded corners and smooth surfaces during the initial machining process, rather than attempting to repair damage later. This preventive approach ensures that the port is created in a damage-free state with optimized geometry that prevents future cracking, eliminating the need for subsequent repair operations that would compromise structural integrity.
3Productivity
If sharp corners are present at the port sidewalls, then manufacturing is simpler, but damage initiation and cracking are more likely
Solution Approach 1:
The patent applies curvature by replacing sharp corners with rounded surfaces at the bottom of the entry port sidewalls. This design modification eliminates stress concentration points that serve as crack initiation sites, thereby preventing damage while maintaining manufacturing efficiency through optimized tooling paths and specialized milling tools designed for corner rounding.
Data Source
AI summary
A turbine rotor includes a rotor body and a balancing weight slot defined in an exterior circumference of the body. The balancing weight slot has a first axial width and a first radially outward facing surface at a first radial distance from a rotor axis. The rotor also includes a balancing weight entry port defined in a portion of the exterior circumference of the rotor body and aligned with the balancing weight slot. The balancing weight entry port has a second axial width greater than the first axial width and a second radially outward facing surface at a second radial distance from the axis of the rotor body that is smaller than the first radial distance. A method may include machining the entry port into the rotor with a tool. The method may be applied to a new rotor, or to remove cracks initiating from a previous entry port.