Rolling-element bearing cage bridge cross-section geometry
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Solution Overview
Problem
Conventional rolling-element bearing cages are prone to breakage due to material weakening caused by recesses intended to prevent rubbing between rolling elements and the cage, leading to potential bearing failure under recurring loads.
Innovation Solution
The rolling-element bearing cage features a bridge section with a cross-sectional area that has a greater edge length than a rectangle with the same area, enhancing bending stiffness and moment of resistance, and includes profile reinforcements such as U-profiles or other shapes to increase stiffness in regions prone to failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If recesses are introduced in the bridge region to prevent rubbing between rolling elements and the cage, then rubbing is reduced, but the bridge width and material strength are weakened, leading to increased risk of cage breakage
Solution Approach 1:
The invention applies different geometric properties to different regions of the bridge cross-section. By creating a non-rectangular cross-sectional shape with increased edge length in specific areas, the bridge achieves localized reinforcement at critical stress points while maintaining the necessary recesses for preventing rubbing. This allows the bridge to have varying material distribution optimized for both rubbing prevention and structural strength.
Solution Approach 2:
The invention transitions from a simple rectangular cross-section (two-dimensional geometry) to a complex non-rectangular cross-section with increased edge length. This dimensional complexity allows the bridge to achieve higher bending stiffness and moment of resistance without increasing the overall cross-sectional area, thereby preventing rubbing while maintaining strength.
2Reliability
If shot peening treatment is applied to reduce bridge breakage tendency, then compressive stresses are reduced at bridge surfaces, but the treatment is very expensive and may not be sufficiently effective
Solution Approach 1:
The invention changes the geometric parameters of the bridge cross-section from a standard rectangle to a non-rectangular shape with increased edge length. This parameter change inherently provides structural reinforcement and stress distribution improvements without requiring additional post-processing treatments like shot peening, thereby reducing manufacturing costs while maintaining or improving reliability.
Solution Approach 2:
The bridge structure itself, through its optimized non-rectangular cross-sectional geometry, provides the reinforcement and stress management functionality that would otherwise require expensive external treatments like shot peening. The geometry design inherently creates compressive stress distribution and increased bending stiffness, making the structure self-reinforcing without additional manufacturing steps.
3Strength
If the bridge cross-section is increased to enhance bending stiffness, then the risk of cage breakage is reduced, but the overall cage size and material usage increase
Solution Approach 1:
The invention achieves increased bending stiffness not by simply enlarging the cross-sectional area, but by changing the cross-sectional shape to a non-rectangular configuration with increased edge length. This dimensional optimization allows the bridge to achieve higher moment of resistance and bending stiffness while maintaining or reducing the overall material quantity compared to a larger rectangular section.
Solution Approach 2:
The invention optimizes the geometric parameters of the bridge cross-section by transitioning from a rectangular to a non-rectangular shape with specific edge length characteristics. This parameter optimization enables the bridge to achieve maximum bending stiffness with minimum material usage, as the non-rectangular geometry distributes material more efficiently to resist bending stresses.
Data Source
AI summary
A rolling-element bearing cage or segment configured to guide at least one rolling element includes a first circumferential ring connected to a second circumferential ring by a plurality of axially extending bridges. A first one of the bridges includes a first axial portion that has a cross-section perpendicular to the axial direction and a cross sectional area and a peripheral length. The peripheral length of the cross section of the first axial portion is greater than a peripheral length of a smallest rectangle bounding the cross section.