Spindle Bearing Layout for Radial Load and Heat Control

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Solution Overview

Problem

In spindle devices with multiple rows of angular contact ball bearings, the inner bearings tend to overheat due to poor heat dissipation, leading to potential seizure, detachment, or creep, and increasing the machine size and maintenance complexity.

Innovation Solution

A spindle device design with a pair of load point side bearing portions having three or more rows of angular contact ball bearings and a pair of counter-load point side bearing portions with two or more rows, strategically positioned to distribute the load and reduce frictional heat, including specific curvature ratios and contact angles to minimize heat generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the number of rows of angular contact ball bearings is increased to improve radial load resistance, then load capacity is improved, but the machine size increases and handling performance during repair work decreases

Engineering Contradiction:
Improveradial load resistanceVSAvoidmachine size
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The bearing arrangement is segmented into multiple rows with different configurations. Specifically, the first and second angular contact ball bearings are arranged in one row, while the third and fourth angular contact ball bearings are arranged in another row, allowing each segment to bear specific loads efficiently without requiring excessive numbers of bearings throughout

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the bearing assembly have different numbers of bearing rows based on local load requirements. The load point side bearing portions have three or more rows to handle concentrated loads, while the counter-load point side bearing portions have two or more rows, creating a non-uniform distribution that optimizes both load capacity and compactness

Inventive Principle:
Principle #3Local quality

2Strength

If the number of rows of angular contact ball bearings is increased to improve radial load resistance, then load capacity is improved, but heat dissipation deteriorates and temperature rise occurs

Engineering Contradiction:
Improveradial load resistanceVSAvoidbearing temperature
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The bearing assembly is segmented into two distinct rows: one row for the first and second angular contact ball bearings, and another row for the third and fourth angular contact ball bearings. This segmentation allows heat generated in each row to dissipate more effectively rather than being concentrated in a single multi-row configuration

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The bearing portions are differentiated by their thermal and load characteristics. The load point side bearing portions (with three or more rows) handle higher loads but are positioned to manage heat generation, while the counter-load point side bearing portions (with two or more rows) provide additional support with better heat dissipation characteristics

Inventive Principle:
Principle #3Local quality

3Strength

If the number of rows of angular contact ball bearings is increased to improve radial load resistance, then load capacity is improved, but the number of components increases leading to more complex maintenance

Engineering Contradiction:
Improveradial load resistanceVSAvoidnumber of bearing rows
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The bearing system is divided into two functional segments: load point side bearing portions and counter-load point side bearing portions. Each segment contains a specific number of rows (three or more and two or more respectively), creating a manageable structure that balances load capacity with maintainability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple angular contact ball bearings are merged into paired configurations where the first and second bearings form one functional unit, and the third and fourth bearings form another unit. This merging reduces the effective number of independent components that need maintenance while maintaining the load capacity of multiple rows

Inventive Principle:
Principle #5Merging (Combining)

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

This design effectively distributes the load, reduces frictional heat, and prevents overheating, thereby enhancing the spindle's durability and handling during maintenance.

Implementation Method 1

a plurality of rolling elements 9 rotatably held by a cage 8 are provided between an inner ring 5 and an outer ring 7 so as to be rotatable at a contact angle α

Methodology Applied
Scientific EffectRolling contact: Ball Bearing

Implementation Method 2

frictional heat is generated due to contact between raceway surfaces of the inner ring 5 and the outer ring 7 and the rolling elements 9

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

the angular contact ball bearings 3B and 3C arranged on an inner side and sandwiched by the angular contact ball bearings 3A and 3D have poor heat dissipation and temperatures of the bearings tend to rise

Methodology Applied
Scientific EffectHeat dissipation: Convection

Implementation Method 4

a temperature of the bearing rises

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3851688B1Spindle device
Publication Date: 2022.10.19 NSK LTD
  • EP3851688B1 patent drawingFigure 1
  • EP3851688B1 patent drawingFigure 2
  • EP3851688B1 patent drawingFigure 3

AI summary

A spindle device, in which a rotating shaft to which a radial load is applied is supported to a housing via a bearing portion, is provided. The bearing portion includes: a pair of load point side bearing portions that are spaced apart from each other in an axial direction, with a load point where the radial load is applied to the rotating shaft serving as a center, and each of which has three or more rows of angular contact ball bearings; and a pair of counter-load point side bearing portions that are spaced apart from each other at an outer side in the axial direction from the pair of load point side bearing portions, and each of which has two or more rows of angular contact ball bearings.