Angular Ball Bearing Cage Pocket Design for Slip Prevention

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Solution Overview

Problem

Angular ball bearings with ball guide type cages experience revolution slip and wear when subjected to large axial loads due to contact between the ball and the cage pocket edge, leading to impaired rotation and potential slip between the inner ring and ball, which existing technologies fail to prevent effectively.

Innovation Solution

A cage design for angular ball bearings featuring a large-diameter and small-diameter circular parts with specific pocket dimensions, including a cylindrical hole and conical hole configuration, where the inside diameters and lengths are optimized to prevent edge contact between the ball and the cage, with A/Dw ≤ 0.94, C/B ≤ 0.35, and D/Dw ≥ 0.04, ensuring the ball is not restricted excessively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a ball guide type cage is used in an angular ball bearing under large axial load, then the bearing can support the load, but the rolling element load on the anti-load side becomes very small causing the ball to contact the pocket edge and impair cage revolution

Engineering Contradiction:
Improveaxial load capacityVSAvoidcage revolution stability
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The pocket structure is designed with different zones: a cylindrical hole portion with constant diameter and a conical hole portion with reducing diameter. This local differentiation in geometry ensures that the ball is properly guided and positioned, preventing edge contact while maintaining load support capability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Specific dimensional parameters are established to prevent ball-pocket edge contact: the ratio A/Dw ≤ 0.94 (conical hole diameter to ball diameter), C/B ≤ 0.35 (cylindrical hole length to diameter), and D/Dw ≥ 0.04 (clearance between cage and ball). These parameter constraints ensure reliable cage revolution under varying load conditions.

Inventive Principle:
Principle #35Parameter changes

2Force

If the rolling element load is reduced on the anti-load side, then the drive force from the ball to the cage decreases, but this causes the ball to contact the pocket edge and promotes revolution slip between the inner ring and ball

Engineering Contradiction:
Improverolling element loadVSAvoidcage revolution smoothness
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The conical hole portion creates a gradual transition zone that guides the ball smoothly into the cylindrical hole portion. This localized geometric feature ensures continuous ball-cage contact without edge impact, maintaining smooth cage revolution even when drive force varies with load conditions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The conical hole provides a curved transition surface that facilitates smooth ball movement into the cylindrical pocket. This curvature eliminates sharp edges that would cause contact and revolution slip, ensuring continuous and smooth cage rotation under varying operational loads.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Reliability

If the ball is prevented from contacting the pocket edge, then cage wear is reduced, but the pocket geometry must be precisely controlled within specific dimensional ratios

Engineering Contradiction:
Improvecage wear resistanceVSAvoidpocket dimensional accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention establishes specific dimensional parameter ranges (A/Dw ≤ 0.94, C/B ≤ 0.35, D/Dw ≥ 0.04) that, when satisfied, guarantee prevention of ball-pocket edge contact. These parameter constraints provide clear manufacturing targets that ensure both wear resistance and manufacturability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The pocket is divided into two distinct portions: a cylindrical hole portion and a conical hole portion. This segmentation allows each portion to be optimized independently for its specific function while maintaining overall manufacturability within the specified parameter ranges.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2988010B1Angular ball bearing cage
Publication Date: 2019.09.04 NSK LTD
  • EP2988010B1 patent drawingFigure 1
  • EP2988010B1 patent drawingFigure 2
  • EP2988010B1 patent drawingFigure 3

AI summary

Each pocket (55) of the cage (50) of the angular ball bearing (10) has a cylindrical hole (56) that opens on the outer circumferential surface (50a) of the cage and a conical hole (58) that opens on the inner circumferential surface (50b) of the cage. (A)/(Dw) < 0.94, wherein (A) is the internal diameter of the conical hole (58) at the inner circumferential surface (50b) of the cage and (Dw) is the diameter of the ball (40). (C)/(B) ≤ 0.35, wherein (C) is the distance over which the internal diameter of the cylindrical hole (56) is constant and (B) is the internal diameter of the cylindrical hole (56). (D)/(Dw) ≥ 0.04, wherein (D) is the minimum difference between the PCD of the ball (40) and the external diameter of the cage (50) and (Dw) is the ball diameter.