Roller Bearing End Profile for Non-Elliptical Flange Contact

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Solution Overview

Problem

Radial cylindrical bearings face challenges in managing both radial and axial loads effectively, as existing designs with elliptical contact footprints can lead to undesirable edge stresses and suboptimal contact stress management, especially at light loads.

Innovation Solution

The roller bearing features a profile with a principal segment and adjacent segments, where the principal segment has a greater curvature radius than the others, and is tangentially blended with them, allowing for a non-elliptical contact footprint that adjusts with load, preventing edge stress and optimizing contact attributes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If elliptical contact footprint is used to manage contact stress, then contact stress management is improved, but edge stresses increase due to interaction with flange face edges

Engineering Contradiction:
Improvecontact stressVSAvoidedge stresses
Core Design Contradiction:
Stress or pressureVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by using a non-elliptical contact footprint shape (such as rectangular or square) instead of the conventional elliptical shape. This asymmetric design allows the contact area to be positioned optimally on the flange face, avoiding edge interaction and the resulting edge stresses while maintaining effective contact stress management throughout the contact region.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by designing the contact footprint with non-uniform stress distribution characteristics. The contact area is optimized to concentrate stress in the central region away from edges, creating different stress qualities in different zones of the contact area - high contact stress in the center for load bearing, and zero or minimal stress near edges to prevent edge stresses.

Inventive Principle:
Principle #3Local quality

2Stress or pressure

If contact ellipse size increases with contact load, then contact stress management is improved, but contact footprint interacts with flange face edges at higher loads

Engineering Contradiction:
Improvecontact stressVSAvoidcontact footprint shape
Core Design Contradiction:
Stress or pressureVSShape

Solution Approach 1:

The patent uses a non-elliptical contact footprint shape that maintains its geometric form across varying loads. Unlike elliptical footprints that expand and may interact with edges, the asymmetric design (such as rectangular) allows for controlled expansion that preserves the optimal shape characteristics throughout the load range, preventing edge interaction even at higher loads.

Inventive Principle:
Principle #4Asymmetry

3Stress or pressure

If roller end profile is designed for optimal contact at light loads, then contact stress management is improved, but edge stress prevention may be compromised

Engineering Contradiction:
Improvecontact stressVSAvoidedge stresses
Core Design Contradiction:
Stress or pressureVSObject-affected harmful factors

Solution Approach 1:

The patent applies universality by designing a roller end profile that serves multiple functions across different load conditions. The non-elliptical contact footprint design enables the same profile to optimize contact stress at light loads while simultaneously preventing edge stress interaction at heavy loads, eliminating the need for load-specific profile adjustments and providing universal performance across the entire operating range.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3615821B1Non-elliptical contact profile for roller bearing
Publication Date: 2022.07.27 THE TIMKEN CO(US)
  • EP3615821B1 patent drawingFigure 1~2
  • EP3615821B1 patent drawingFigure 3~4
  • EP3615821B1 patent drawingFigure 5~6

AI summary

A roller bearing includes an inner race ring, an outer race ring, and a roller arranged between and in contact with the inner and outer rings. The bearing has a flange (31,131) on the inner race ring at one axial end, and a flange (21,121) on the outer race ring at an opposite axial end. One of the flanges, and/or an end of the roller, includes at least one principal segment (53,153) intermediate two additional segments (52,152;54,154). The principle segment is tangentially blended with the two additional segments, and the principle segment has a first curvature that is different from the respective curvatures of the two additional segments. A non-elliptical contact footprint can be obtained by composite profiles at the contact location between the roller end and the mating flange face.