Molten Metal Rotor-Shaft Locking Structure for Breakage Prevention
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Solution Overview
Problem
Existing molten metal pumps face issues with rotor shaft breakage at the coupling location due to applied driving force, leading to erratic rotor movement and difficulty in removing the rotor shaft, often requiring both components to be replaced.
Innovation Solution
A rotor shaft with outwardly-extending projections that fit into a cavity of the rotor, allowing the projections to be retained under the rotor's upper surface and pressed against an abutment to transmit driving force, preventing separation and facilitating secure connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a traditional coupling connects the rotor shaft to the motor shaft, then the driving force can be transmitted, but the rotor shaft breaks at the coupling location due to applied driving force
Solution Approach 1:
The rotor shaft is segmented into multiple sections: a motor shaft section, a coupling section with keyway, and a rotor shaft section. This segmentation allows the driving force to be distributed across different structural elements (keyway, coupling interface) rather than concentrated at a single weak point, preventing breakage while maintaining power transmission capability.
2Reliability
If the rotor shaft breaks at the coupling location, then the driving force transmission fails, but removing the rotor shaft becomes difficult and both components must be replaced
Solution Approach 1:
The coupling is designed with a keyway and key configuration that creates a preliminary mechanical interlock between the motor shaft and rotor shaft. This preliminary action ensures that the components remain securely connected during operation, preventing erratic rotor movement, while also facilitating easier removal when maintenance is needed by providing defined separation interfaces.
3Ease of operation
If a threaded connection is used to attach the rotor shaft to the rotor, then the connection can be secured, but the threads fail over time causing erratic rotor movement
Solution Approach 1:
The threaded mechanical connection is replaced with a keyway-based mechanical interlock system. The key fits into the keyway on the rotor shaft, creating a positive mechanical connection that transmits torque without relying on threads. This substitution eliminates thread failure over time while maintaining secure connection and preventing erratic rotor movement.
Data Source
AI summary
A molten metal rotor receives and retains an end of a molten metal rotor shaft. The rotor shaft has one or more projections at the end received in the rotor. The rotor has an inner cavity, a top surface with an opening leading to the inner cavity, and at least one abutment. The opening includes one or more portions for allowing each projection to pass through the opening and into the inner cavity. The rotor and/or shaft are then rotated so at least one of the outwardly-extending projections is under the top surface of the rotor and is against an abutment. A molten metal pump, rotary degasser scrap melter or other device used in molten metal may utilize a rotor/shaft combination as disclosed herein.