Rotor Corrosion Protection via Hot Isostatic Pressing

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Solution Overview

Problem

Industrial electric motors used for compressing chemically aggressive process gases face long-term impairment due to corrosion of copper parts, existing anti-corrosion methods being either costly or inefficient.

Innovation Solution

A method involving hot isostatic pressing to apply a metallic anti-corrosion layer around the metal core and conductors, using a metallic intermediate layer that diffuses into the core and layer for a strong, uniform connection, and a high-alloy stainless steel or nickel-based alloy like Inconel 625 for enhanced corrosion resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metallic anti-corrosion layer is applied by explosive welding to protect copper conductors, then corrosion resistance is improved, but manufacturing cost and process complexity increase

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A metallic intermediate layer is introduced between the metal core and the anti-corrosion layer. This intermediate layer serves as a mediator that facilitates material diffusion during hot isostatic pressing, enabling strong bonding while avoiding the complexity of explosive welding. The intermediate layer composition is selected to promote diffusion bonding with both the metal core and the anti-corrosion layer.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies hot isostatic pressing with controlled temperature and pressure parameters to achieve diffusion bonding. By changing the thermal and pressure parameters during the process, the metal core, intermediate layer, and anti-corrosion layer are bonded together uniformly. This approach replaces explosive welding with a more controllable and less complex thermal-mechanical process.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If a solid anti-corrosion layer is applied around the metal core, then manufacturing cost is reduced and production is simplified, but connection strength and uniformity may be compromised

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidconnection strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

Hot isostatic pressing with optimized temperature and pressure parameters is applied to the solid anti-corrosion layer. The thermal and pressure parameters are carefully controlled to enable diffusion bonding between the metal core, intermediate layer, and anti-corrosion layer. This ensures strong and uniform connections while maintaining the simplicity of applying a solid protective layer.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The metallic intermediate layer acts as a mediator that enhances the bonding interface between the metal core and the solid anti-corrosion layer. During hot isostatic pressing, material diffusion occurs through this intermediate layer, creating strong metallurgical bonds. This resolves the concern about connection strength while preserving the manufacturing simplicity of using a solid protective layer.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If hot isostatic pressing is used to attach the anti-corrosion layer, then connection uniformity and strength are improved, but process temperature and time requirements increase

Engineering Contradiction:
Improveconnection uniformityVSAvoidprocess time
Core Design Contradiction:
StrengthVSLoss of time

Solution Approach 1:

The hot isostatic pressing parameters (temperature, pressure, and time) are optimized to achieve the desired connection quality in the shortest time. By adjusting these parameters, uniform diffusion bonding is achieved between the metal core, intermediate layer, and anti-corrosion layer. The process is designed to balance connection quality with production efficiency, avoiding excessive processing times.

Inventive Principle:
Principle #35Parameter changes

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 provides a cost-effective, reliable, and mechanically strong anti-corrosion solution that effectively protects the rotor from chemically hostile environments, maintaining motor efficiency even at high speeds and revolutions.

Implementation Method 1

a metallic intermediate layer is applied, from which the material diffuses into the metal core and the anti-corrosion layer by hot isostatic pressing and holds them together

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

the fastening takes place by hot isostatic pressing, the anti-corrosion layer is at least part of a hot-press encapsulation for isostatically pressing the conductors in the metal core

Methodology Applied
Scientific EffectHot isostatic pressing: Hot Isostatic Pressing

Data Source

PatentEP2404368B1Rotor for an electric motor and a process for producing said rotor
Publication Date: 2018.06.06 SIEMENS AG
  • EP2404368B1 patent drawingFigure 1~2
  • EP2404368B1 patent drawingFigure 3~6

AI summary

The invention relates to a rotor (2) for an electric motor, comprising a metal core (6), electrical conductors (12) arranged thereon, and a metallic corrosion protection layer (38, 44) enveloping the metal core (6) and the conductors (12). It is proposed that the corrosion protection layer (38, 44) be laid around the metal core (6) and the conductors (12) as a solid body and fastened at least to the metal core (6). The rotor (2), which is suitable for a high-speed electric motor for the industrial sector, can be produced at low cost and can be used reliably to compress chemically aggressive industrial process gases.