Solid-Lubrication Rolling Bearing with Amorphous Carbon Skeleton

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Solution Overview

Problem

The existing solid-lubrication rolling bearings with graphite-based solid lubricants suffer from low material strength, hardness, impact resistance, and wear resistance, leading to shortened life and instability at elevated temperatures.

Innovation Solution

A solid-lubrication rolling bearing is developed using a solid lubricant composed of amorphous and self-sintering carbon material powder, graphite powder, and a binder, with a preferred weight ratio of 50-60% carbon material powder to 25-40% graphite powder, and optionally including W, Mo, MoS2, carbon fiber, or carbon nanotubes to enhance strength and wear resistance, along with a unique separator design to prevent uneven distribution and rotational locking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If graphite powder and binder are used as solid lubricant, then lubrication performance at elevated temperatures is improved, but material strength and hardness are reduced

Engineering Contradiction:
Improveelevated temperature lubrication performanceVSAvoidmaterial strength and hardness
Core Design Contradiction:
TemperatureVSStrength

Solution Approach 1:

The patent uses a composite material consisting of graphite powder (20-40 wt%), amorphous carbon powder (40-60 wt%), and binder (10-30 wt%). The amorphous carbon forms a sintered skeleton structure that provides strength and hardness, while graphite particles embedded in this skeleton provide lubrication at elevated temperatures. This composite structure resolves the contradiction by combining materials with complementary properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention creates different local structures within the solid lubricant: the amorphous carbon forms a sintered skeleton structure in certain regions providing mechanical strength, while graphite particles are distributed in other regions providing lubrication. This local differentiation of material properties allows simultaneous achievement of strength and lubrication performance.

Inventive Principle:
Principle #3Local quality

2Temperature

If graphite-based solid lubricant is used, then lubrication at elevated temperatures is achieved, but wear resistance and impact resistance are reduced

Engineering Contradiction:
Improveelevated temperature operationVSAvoidwear resistance and impact resistance
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The composite structure combines amorphous carbon with sintered skeleton properties for wear and impact resistance, and graphite particles for lubrication. The binder holds graphite particles firmly in the sintered skeleton, preventing particle loss during wear and impact. This composite approach simultaneously achieves elevated temperature lubrication and improved reliability.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The amorphous carbon sintered skeleton acts as an intermediary structure that provides mechanical support and holds graphite particles in place. This skeleton structure transfers and distributes mechanical stresses, protecting the graphite particles from direct impact and wear, thereby improving overall reliability while maintaining lubrication function.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If separator size is reduced to increase rolling element density, then basic rated load is improved, but uneven distribution and rotational locking may occur

Engineering Contradiction:
Improvebasic rated loadVSAvoidrolling element distribution stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The restricting members are pre-installed in the separator to define specific movement ranges for rolling elements before operation begins. These restricting members create predetermined pathways and stop positions that guide rolling element distribution, preventing uneven clustering and rotational locking while allowing sufficient density for high basic rated load.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The restricting members allow controlled dynamic movement of rolling elements within defined ranges rather than complete freedom of movement. This dynamic constraint system enables rolling elements to adjust positions during operation while maintaining overall uniform distribution, preventing both excessive density and rotational locking.

Inventive Principle:
Principle #15Dynamics

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 new solid lubricant achieves high material strength, hardness, and wear resistance, extending the life of the bearing and preventing unintended disassembly, while the separator design ensures stable operation and increased basic rated load without the need for connecting members.

Implementation Method 1

amorphous and self-sintering carbon material powder... forms a skeleton structure in which adjacent carbon material particles are combined with each other after firing due to the self-sintering property

Methodology Applied
Scientific EffectSelf-sintering: Sintering

Implementation Method 2

The graphite particles are held by the skeleton structure and thus, are hard to fall off. This can increase material strength and improve impact resistance and wear resistance

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3048162B1Solid-lubrication rolling bearing
Publication Date: 2020.12.30 NTN CORP
  • EP3048162B1 patent drawingFigure 1~3
  • EP3048162B1 patent drawingFigure 4~5
  • EP3048162B1 patent drawingFigure 6~7

AI summary

A solid lubricant 11 is formed by molding and firing powder that includes amorphous and self-sintering carbon material powder 12, graphite powder 13, and a binder 14. The solid lubricant has high material strength and hardness, and also excellent impact resistance and wear resistance.