Squirrel-Cage Rotor Bar-to-Disc Joining by Hot-Formed Alloying

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Solution Overview

Problem

Existing methods for producing squirrel-cage rotors of asynchronous machines are costly, inefficient, and prone to quality variability due to high material and tool wear, and the connection of conductor bars to short-circuiting rings is laborious and costly, especially in high-power applications.

Innovation Solution

A method involving the insertion of conductor bars into a magnetically conductive body, coating them with a thin layer of material like tin, and using hot-forming to create a material-fit connection with a short-circuiting disc, eliminating the need for pressure diecasting and welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If pressure diecasting techniques are used to produce squirrel-cage rotors, then production efficiency is improved, but manufacturing cost increases and quality variability worsens

Engineering Contradiction:

Improveproduction efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent replaces the pressure diecasting mechanical system with a welding-based assembly system. Conductor bars are individually welded to short-circuiting rings instead of being cast together, eliminating the need for expensive and wear-prone diecasting tools while maintaining production efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent segments the rotor production process into separate components (conductor bars, short-circuiting rings, and magnetically conductive body) that are manufactured independently and then assembled through welding. This allows each component to be optimized separately and reduces the complexity and cost of tooling.

Inventive Principle:

Principle #1Segmentation

2Productivity

If pressure diecasting techniques are used to produce squirrel-cage rotors, then production efficiency is improved, but quality consistency worsens

Engineering Contradiction:

Improveproduction efficiencyVSAvoidquality consistency

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If soldering is used to connect conductor bars to short-circuiting rings, then electrical connection is improved, but production cost increases

Engineering Contradiction:

Improveelectrical connection qualityVSAvoidproduction cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the connection parameter from soldering (which requires silver-containing solder and complete filling of circumferential solder tanks) to welding, which uses less expensive materials and processes. The welding process creates reliable electrical connections without the high material costs associated with silver-based solders.

Inventive Principle:

Principle #35Parameter changes

4Productivity

If resistance welding is used to connect conductor bars to short-circuiting rings, then production speed is improved, but energy consumption increases

Engineering Contradiction:

Improveproduction speedVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent employs periodic action by welding conductor bars in sequential batches rather than attempting to weld all bars simultaneously. The short-circuiting ring is divided into multiple welding zones, and welding proceeds in stages, allowing current to be applied periodically to different sections. This reduces the total current required at any one time while maintaining production speed.

Inventive Principle:

Principle #19Periodic action

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 method produces a highly conductive and mechanically stable connection between conductor bars and short-circuiting discs, reducing production costs and improving efficiency and rotational speed capabilities of the squirrel-cage rotor.

Implementation Method 1

subsequently heating, in particular hot-forming, the axially pushed-on short-circuiting disc, while an almost simultaneous contacting of the conductor bars with at least one short-circuiting disc is effected

Methodology Applied

Scientific EffectHot-forming: Heating

Data Source

PatentUS12395049B2Method for producing a squirrel-cage rotor of an asynchronous machine

Publication Date: 2025.08.19 INNOMOTICS GMBH

AI summary

In a method for producing a squirrel-cage rotor of an asynchronous machine, conductor bars of a first conductive material are inserted into slots of a magnetically conductive body such as to project out of at least one end side to form a projection. A short-circuiting disc of a second conductive material is positioned under pressure on the projection with a clearance fit of approximately 0.1 mm relative to a radially outwardly open recess of the short-circuiting disc. The short-circuiting disc is heated while the conductor bars virtually contact the short-circuiting disc. At least the projection of the conductor bars is coated with a third material at a layer thickness to form an alloy with the first and second materials after heating so that the third material is fully dispersed in the first and second materials as a result of the third material being diffused into the first and second materials.