Two-Piece Ball Bearing Cage for High-Speed Wear Stability
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Solution Overview
Problem
Deep groove ball bearings with snap cages face issues at high speeds due to centrifugal force causing axial web bending, reduced dynamic stability, and increased wear, especially when compared to solid cages which are guided on two rims rather than one.
Innovation Solution
A two-piece cage design where one part is a snap-in cage with axial webs forming ball pockets, and the second part provides stability, joined by ultrasonic or laser welding, ensuring the cage is closed on both axial ends and maintains ball retention with defined clearance, enhancing wear resistance and stability at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a snap cage with axial webs is used to retain balls in deep groove ball bearings, then the cage can be inserted axially and balls are held positively with defined clearance, but at high speeds the free ends of axial webs bend outwards due to centrifugal force causing increased wear and impaired running behavior
Solution Approach 1:
The cage is divided into two separate cage parts that are joined together. The first cage part includes axial webs for ball retention, while the second cage part provides structural support and guidance. This segmentation allows each part to be optimized for its specific function, preventing the bending issue while maintaining ease of insertion.
Solution Approach 2:
The two cage parts are joined together to form a combined structure that merges the ball-retaining function of the first cage part with the guidance and stability function of the second cage part. This merging creates a unified cage structure that performs multiple functions simultaneously, resolving the contradiction between ease of insertion and high-speed reliability.
2Manufacturing precision
If a crown cage or snap cage is used that is closed on both sides in the axial direction, then balls are retained positively with defined clearance, but the cage is guided on only one rim leading to lower dynamic stability and reduced structural mechanical stability compared to solid cages
Solution Approach 1:
The cage is segmented into two functional parts: the first cage part provides precise ball retention through axial webs, while the second cage part provides structural stability and guidance on both rims. This segmentation allows each part to specialize in one aspect, resolving the contradiction between precision retention and dynamic stability.
Solution Approach 2:
The combined cage structure achieves multi-functionality by integrating ball retention, radial guidance on both rims, and structural stability into a single unified component. The first cage part handles ball retention while the second cage part provides guidance and stability, together creating a universally functional cage that resolves the contradiction.
3Reliability
If two cage parts are joined by ultrasonic welding as proposed in DE 10 2019 206 954 A1, then the cage is closed on both sides and can be used in deep groove ball bearings, but the parting lines positioned in the axial center of ball pockets favor wear since ball pockets wear most in the circumferential direction
Solution Approach 1:
The joining arrangement creates an asymmetric structure where the second cage part is offset relative to the first cage part in the axial direction. This asymmetry positions the parting line away from the axial center of the ball pockets, reducing wear at critical locations while maintaining the beneficial cage closure.
Solution Approach 2:
The joining arrangement is designed so that the parting line between cage parts is positioned in a location that minimizes its impact on ball pocket wear. By placing the parting line away from the axial center where wear is most severe, the local quality of wear resistance is improved at the most critical locations.
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 two-piece cage design improves wear resistance and dynamic stability at high speeds by maintaining ball retention and guiding, reducing wear and distortion, while allowing precise centering and radial guidance, thus enhancing the overall performance of deep groove ball bearings.
Implementation Method 1
The first cage part and the second cage part are joined together in a materially bonded manner by welding, in particular ultrasonic welding
Implementation Method 2
The second cage part is guided on a rim of the bearing outer ring in the radial direction
Data Source
AI summary
There is provided a ball bearing having a cage and balls held in the cage, the balls arranged one behind the other at a distance from one another in a circumferential direction about an axis of rotation of the ball bearing. The cage assembled from at least two cage parts joined to one another in a bonded manner and completely enclose the balls in a circumferential surface extending around the axis of rotation. A first cage part designed as a snap cage having axial webs projecting in the direction of the axis of rotation from a closed base ring and form ball pockets therebetween them, the first cage part encloses the balls along their outer circumference by more than 180°, holds the balls positively while forming an undercut and limits displacement of the balls within the circumferential surface in the direction of the at least one other second cage part.