Cylindrical Roller Bearing Cage with Variable Holding Angles

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Solution Overview

Problem

Cylindrical roller bearings used in machine tool spindles face issues with squeak noise and wear due to roller skewing and biting into cage columns at high speeds, and insufficient lubrication leading to cage wear, especially under high-speed and negative radial gap conditions.

Innovation Solution

A cylindrical roller bearing design featuring a resin cage with annular and column portions that include roller holding portions with specific geometry to guide rollers on both outer and inner diameters, preventing skewing and biting, and incorporating an inner diameter side protrusion to manage thermal and centrifugal expansion, ensuring reduced contact and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the roller holding angle is made smaller to prevent roller biting into cage columns at high speed, then high-speed performance is improved, but the roller may skew or tilt at low speed causing squeak noise and wear

Engineering Contradiction:

Improvehigh-speed performanceVSAvoidroller skew prevention

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The invention applies different roller holding angles to different regions of the cage. Specifically, the cage has a first roller holding angle in a first region and a second roller holding angle in a second region, where the angles differ. This allows optimization for both low-speed and high-speed conditions by having different geometric characteristics in different locations around the roller path.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention makes the roller holding angle variable rather than constant. By having different angles in different regions, the effective roller holding angle becomes dynamic relative to the roller position, allowing the cage to adapt its geometry to the operating conditions at different speeds and positions.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the outer diameter restraint type cage is used to prevent roller skew at low speed, then squeak noise and wear are suppressed, but the roller holding angle cannot be made smaller than a certain value limiting high-speed performance

Engineering Contradiction:

Improveroller skew suppressionVSAvoidhigh-speed capability

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

3Speed

If the outer ring guide type cage is used for high-speed rotation, then the cage can handle centrifugal forces, but wear occurs between the cage and outer ring when lubrication is insufficient

Engineering Contradiction:

Improvehigh-speed rotation capabilityVSAvoidcage wear resistance

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The invention introduces a resin cage as an intermediary component between the roller and the bearing rings. This resin cage with specifically designed roller holding portions prevents direct metal-to-metal contact and reduces wear, while still allowing the bearing to operate at high speeds. The cage material and geometry act as a mediator that protects the bearing rings from wear.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively suppresses squeak noise and wear at low speeds and prevents roller biting into cage columns at high speeds by guiding rollers on the inner diameter side, maintaining performance and reducing contact with the cage.

Implementation Method 1

a plurality of cylindrical rollers rollably disposed between the outer ring raceway surface and the inner ring raceway surface

Methodology Applied

Scientific EffectRolling contact: Roller

Implementation Method 2

Since a guide gap expands due to centrifugal expansion and thermal expansion during operation

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

Since a guide gap expands due to centrifugal expansion and thermal expansion during operation

Methodology Applied

Scientific EffectCentrifugal expansion: Centrifugal Force

Data Source

PatentUS10605303B2Cylindrical roller bearing

Publication Date: 2020.03.31 NSK LTD

AI summary

The column portions of the cage includes roller holding portions which restrain the cylindrical roller on an outer diameter side and an inner diameter side thereof. The roller holding portions are formed such that a radial movement amount of the cage with respect to the cylindrical roller from a state where a revolution center of the cylindrical roller coincides with an axial center of the cage is configured so that an outer diameter side movement amount<an inner diameter side movement amount, and an outer diameter side opening width of the pocket portion>an inner diameter side opening width of the pocket portion. The column portion includes an inner diameter side protrusion which protrudes to an inner diameter side than inner circumferential surfaces of the annular portions and which configures the roller holding portions.