Threaded Rotor Shaft Coupling for Easier Broken Shaft Removal

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Solution Overview

Problem

Existing rotor shaft couplings in molten metal pumps and degassers tend to break at the point of contact, necessitating difficult removal of the broken end from the coupling opening.

Innovation Solution

A coupling design featuring a collar with a cavity and a protrusion, where the rotor shaft is threaded to align with the protrusion, allowing for easier removal of a broken shaft by unthreading or chiseling, reducing the complexity of repair.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a traditional coupling design is used for the rotor shaft, then the coupling can transmit power effectively, but the coupling and rotor shaft tend to break at the point of contact, requiring difficult removal of the broken end

Engineering Contradiction:

Improvecoupling strengthVSAvoidbroken shaft removal

Core Design Contradiction:

StrengthVSEase of repair

Solution Approach 1:

The coupling is segmented into a body and a separate removable protrusion element. The protrusion can be detached from the coupling body when the rotor shaft breaks, allowing the broken shaft end to be easily removed without damaging the coupling body. This segmentation resolves the contradiction by maintaining structural integrity during operation while enabling easy repair when failure occurs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The protrusion is designed to be extractable from the coupling body. When the rotor shaft breaks at the contact point, the protrusion can be taken out along with the broken shaft end, simplifying the repair process. This extraction capability directly addresses the ease of repair concern while maintaining coupling strength during normal operation.

Inventive Principle:

Principle #2Taking out (Extraction)

2Device complexity

If a traditional fixed coupling design is used, then the structure is simple, but the broken shaft end causes damage to the coupling opening and requires complex removal procedures

Engineering Contradiction:

Improvecoupling structureVSAvoidcoupling opening damage

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

By segmenting the coupling into a body and a removable protrusion, the design protects the coupling body opening from damage during shaft removal. The protrusion absorbs the mechanical stress of removal, preventing damage to the main coupling structure while adding only minimal complexity to the overall design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The removable protrusion allows the broken shaft end to be extracted without causing harmful effects to the coupling opening. The protrusion acts as a sacrificial element that protects the permanent coupling body from damage during the repair process.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12560169B2Coupling and rotor shaft for molten metal devices

Publication Date: 2026.02.24 MOLTEN METAL EQUIP INNOVIATIONS LLC

AI summary

A coupling has an opening and a protrusion extending downward from the opening. The protrusion has threads that are preferably positioned outside of the opening. A rotor shaft that connects to the coupling has an internal bore with threads that receives and retains the protrusion, such as by a threaded connection between the two, so the protrusion applies driving force to the shaft.