Strain-Hardened Plain Bearing for Gas Turbine Diffuser Wear

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Solution Overview

Problem

Variable-setting diffuser mechanisms in gas turbines experience significant wear due to operating conditions, leading to reduced functionality and life expectancy of contact surfaces in plain bearing systems, particularly in non-lubricated environments.

Innovation Solution

The use of strain-hardened surface layers on austenitic steel bearing elements in contact with martensitic steel sleeve elements, combined with graphite varnish for improved running-in, enhances wear resistance and extends the life of these components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional materials are used for bearing surfaces in non-lubricated environments, then the system can operate without lubrication, but the contact surfaces experience significant wear leading to reduced functionality and life expectancy

Engineering Contradiction:

Improvewear resistanceVSAvoidlife expectancy of contact surfaces

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention applies strain hardening to the first bearing element, fundamentally changing its surface properties. This cold plastic deformation process increases surface hardness and strength, creating a more wear-resistant surface that can withstand the harsh non-lubricated operating conditions while extending the life expectancy of the bearing contact surfaces

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite structure by combining the strain-hardened first bearing element with the second bearing element. The strain-hardened surface layer acts as a wear-resistant composite material that complements the base material, providing enhanced protection against wear in the non-lubricated environment

Inventive Principle:

Principle #40Composite materials

2Strength

If austenitic steel is used for the first bearing element, then good ductility and toughness are achieved, but the surface hardness is insufficient for non-lubricated bearing applications

Engineering Contradiction:

Improvesurface hardnessVSAvoidcomplexity of strain hardening process

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The strain hardening process is applied as a preliminary treatment to the austenitic steel bearing element before assembly. This pre-treatment prepares the surface with enhanced hardness and wear resistance, allowing the component to be manufactured from ductile austenitic steel while achieving the required surface properties for non-lubricated operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical state of the austenitic steel surface through strain hardening, transforming it from a soft, ductile material to a hard, wear-resistant surface layer. This parameter change enables the use of austenitic steel while achieving the necessary surface hardness for bearing applications

Inventive Principle:

Principle #35Parameter changes

3Reliability

If martensitic steel is used for the second bearing element, then high surface hardness is achieved, but the material is more difficult to manufacture and machine

Engineering Contradiction:

Improvewear resistanceVSAvoidmanufacturability of martensitic steel

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Instead of making the entire second bearing element from martensitic steel, the invention inverts the approach by applying strain hardening to the first bearing element. This allows the use of austenitic steel (easier to manufacture) for the first element while still achieving the required wear resistance, effectively swapping the manufacturing complexity between the two elements

Inventive Principle:

Principle #13The other way round (Inversion)

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

The strain-hardening process significantly increases the surface hardness of austenitic steel, matching or exceeding that of martensitic steel, thereby reducing wear and extending the operational life of diffuser mechanisms, preventing premature failure and maintaining aerodynamic efficiency.

Implementation Method 1

the first bearing element has a strain-hardened surface layer. A strain-hardenable material is a material whose mechanical properties are enhanced by cold plastic deformation

Methodology Applied

Scientific EffectStrain hardening: Cold-forming

Implementation Method 2

a varnish such as a graphite varnish is applied to one or other of the contact surfaces to facilitate their running-in

Methodology Applied

Scientific EffectLubrication: Lubrication

Data Source

PatentUS7625176B2Plain bearing between two parts which are movable with respect to each other

Publication Date: 2009.12.01 SAFRAN AIRCRAFT ENGINES SAS

AI summary

The present invention relates to a plain bearing between two parts movable with respect to each other, the first part having a first bearing element made from a first metal and the second part having a second bearing element made from a second metal of higher hardness. The first bearing element has a surface layer hardened by strain hardening. As a result of the invention, the wear between the parts can be reduced and their life can be substantially lengthened. The invention can be advantageously applied to cases in which the first part is a variable-setting diffuser blade and the second part is a gas turbine casing.