Ball Bearing Cage with Selective Soft Plating for High Speed Generators
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Solution Overview
Problem
Existing ball bearings face reduced efficiency due to the balls catching or being impeded from rotation, which is exacerbated by the reduced integrity of the riveted cage assembly when both halves are plated, and uniform clearance between the cage and races is not maintained, leading to undesirable results.
Innovation Solution
The bearing design features bearing cage halves made of a hard material with selective soft plating on surfaces, excluding rivet and contact areas, and optimized clearance ratios between the cage and races to prevent plating on rivet surfaces and contact points, ensuring the rivets extend through uncoated apertures and sit in uncoated ditches, maintaining the structural integrity and reducing plating on the rivet heads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire cage is plated with soft material, then the bearing surfaces are improved, but the structural integrity of the riveted assembly is reduced
Solution Approach 1:
The soft plating is applied selectively only to the ball contact surfaces and pocket surfaces of the cage, while leaving the rivet surfaces and mating surfaces unplated. This local differentiation allows the bearing surfaces to have the desired softness for reduced friction and wear, while the unplated rivet surfaces maintain their structural integrity and bonding strength.
2Ease of manufacture
If uniform clearance is maintained between cage and races, then assembly is simplified, but ball rotation is impeded causing reduced efficiency
Solution Approach 1:
Different clearance values are specified for different locations: a first clearance between the cage outer periphery and outer race inner periphery, and a second clearance between the ball pocket and ball outer periphery. This local differentiation ensures proper ball rotation efficiency while maintaining manufacturability through defined tolerance ranges.
3Ease of operation
If soft plating is applied to all surfaces, then friction is reduced, but rivet bonding is compromised
Solution Approach 1:
The soft plating material (such as silver, copper, or brass) is applied exclusively to surfaces that require low friction for ball rotation, specifically the ball contact surfaces and pocket surfaces. The rivet surfaces, aperture inner surfaces, and ditch surfaces are deliberately left unplated to maintain adequate bonding strength and structural integrity for the riveted assembly.
Data Source
AI summary
A ball bearing has an outer race and an inner race A plurality of ball members are supported radially between the inner and outer races. A pair of bearing cage halves are placed at axial ends of the balls. The bearing cage halves are formed of a first relatively hard material, and have a plating of a softer material on some surfaces The bearing cage halves have pockets facing the balls and with the soft plating The bearing cage halves are riveted together along a contact surface, not including the soft plating. The rivets extend through an aperture in each of the bearing cage halves, not provided with the soft plating. The rivets have heads extending into a ditch, not provided with the soft plating. A rotor sub-assembly, a generator, and a method of maintaining a generator are also disclosed.