Angular Contact Bearing Cage Frustoconical Bridge Design
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Solution Overview
Problem
Angular contact ball bearings with thermoplastic cages face issues of bridge breakage due to misalignment and high friction, leading to stress and premature wear, and existing solutions either increase cost or fail to adequately retain balls.
Innovation Solution
A cage design with frustoconical bridges and hemispherical cells that provide a circumferential clearance, allowing balls to move freely and reducing stress on bridges, while maintaining them in place without deformation, using a thermoplastic material with refined bridge thickness and cylindrical or toroidal tubular casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the radius of the cells is increased to reduce friction between balls and cage faces, then friction is reduced, but the cage thickness must be increased to maintain rim spacing smaller than ball diameter, which raises cost, mass, and moment of inertia
Solution Approach 1:
The invention applies different geometric characteristics to different parts of the cage structure. The bridges have a frustoconical shape with specific angle ranges (30-60 degrees for inner face, 10-30 degrees for outer face), while the cells have spherical facets with specific radius relationships. This localized optimization allows friction reduction without requiring uniform thickening of the entire cage structure.
Solution Approach 2:
The invention changes the geometric parameters of the cage structure, specifically the bridge angles and cell facet radii, to optimize performance. By controlling the frustoconical bridge angles and the relationship between facet radius and ball radius, the design achieves reduced friction while maintaining appropriate rim spacing without increasing overall cage thickness.
2Strength
If the bridges are made thicker to maintain structural integrity, then strength is improved, but adjacent balls become wedged on either side of the bridges, increasing stress and leading to premature breakage
Solution Approach 1:
The invention uses spherical facets for the ball retention recesses and frustoconical shapes for the bridges. The curved surfaces allow balls to be properly positioned and retained without creating stress concentration points. The spherical geometry distributes loads more evenly, preventing the wedging effect that occurs with flat or angular bridge designs.
Solution Approach 2:
The bridges have asymmetric frustoconical geometry with different angles for the inner face (30-60 degrees) and outer face (10-30 degrees). This asymmetric design optimizes the stress distribution and ball positioning, allowing the bridges to maintain structural integrity while preventing ball wedging that would lead to breakage.
3Ease of manufacture
If the cage is made with standard spherical cells, then manufacturing is simplified, but balls cannot move freely to accommodate misalignment, causing high friction and stress on bridges
Solution Approach 1:
The invention creates a dynamic system where balls can move freely within the spherical facets of the cage cells. This movement capability allows the bearing to accommodate misalignment between inner and outer rings dynamically, reducing friction and stress. The frustoconical bridges provide the necessary guidance while allowing the required degrees of freedom.
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 design significantly reduces the risk of bridge breakage and friction, enhancing the longevity of the cage by allowing balls to move circumferentially and maintain position, thus addressing the issues of misalignment and wear.
Implementation Method 1
The edges of these facets form openings whose dimensions, dictated by the cage thickness, are slightly smaller than the diameter of the balls. This allows the balls to be pressed into the recesses, whose edges deform elastically during insertion, and then held securely within the recesses.
Data Source
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AI summary
An angular-contact ball-bearing cage of annular overall shape comprises a plurality of pockets (28) each intended to accommodate a ball (16) of given radius and separated by bridges (26), the pockets (28) being shaped so that they hold the balls (16) in the pockets (28). The cage (10) has a height H measured parallel to the reference axis (100), and the bridges (26) each have an interior radial face facing towards the reference axis (100), tangential to an interior frustoconical envelope and of height Hi measured parallel to the reference axis, greater than or equal to 2/3 of the height of the cage H.