Bearing Raceway Surface Texture Profile for Lubrication
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Solution Overview
Problem
The surface texture of bearing raceways can enhance lubrication but may also cause near-surface stress concentrations, detrimental to durability, and existing designs struggle to balance these effects effectively.
Innovation Solution
A bearing assembly with a central region and recessed side regions, where the central region is smoother than the side regions, created through a two-stage finishing process, enhances lubricant retention and availability, reducing stress concentrations and improving lubrication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surface texture is applied within the contact zone between rolling elements and raceways, then lubricant retention is improved, but near-surface stress concentrations increase which deteriorates surface durability
Solution Approach 1:
The patent applies different surface roughness characteristics to different zones of the raceway: the central contact zone maintains a first roughness profile optimized for lubricant retention, while the side regions have a second roughness profile with different characteristics. This local differentiation allows each zone to serve its specific function without the negative effects of uniform texturing across the entire surface.
Solution Approach 2:
The raceway surface is segmented into distinct zones (central contact zone and side regions) with different surface texture characteristics. This segmentation allows the central zone to provide lubricant retention while the side zones can be optimized for stress distribution, thereby resolving the contradiction between lubrication performance and surface durability.
2Reliability
If surface texture is applied to retain lubricant, then lubrication performance improves, but surface durability may be compromised due to stress concentrations
Solution Approach 1:
Different surface roughness profiles are applied to different locations on the raceway surface. The central contact zone has a roughness profile optimized for lubricant retention, while the side regions have a different profile that reduces stress concentrations. This local quality approach ensures that lubrication performance is improved without compromising overall surface durability.
3Reliability
If a two-stage finishing process is used to create different roughness profiles, then lubrication performance and surface durability are optimized, but manufacturing complexity increases
Solution Approach 1:
The first roughness profile is created during an initial finishing operation, establishing the base surface texture for lubricant retention. Then, a second finishing operation selectively modifies the side regions to create the second roughness profile. This sequential approach builds upon the previous operation rather than requiring complete re-processing, thereby managing manufacturing complexity while achieving the desired dual-roughness configuration.
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 described surface texture profile increases the hydrodynamic lubricant film thickness, reduces side leakage, and enhances lubrication performance without compromising surface durability, leading to improved bearing service life.
Implementation Method 1
The described surface texture profile increases the hydrodynamic lubricant film thickness, reduces side leakage, and enhances lubrication performance
Data Source
AI summary
A bearing assembly having an inner race ring (14) that defines an inner raceway and an outer race ring that defines an outer raceway on which the plurality of rolling elements (22) roll. The bearing raceways are machined using surface finishing operations to create preferred surface profiles and textures for improving lubrication performance. The profile of the raceway is initially created using a first grinding process to form a rough surface profile including a rough central band (34) and rough recessed side bands (38). A second grinding process is used to smooth the central band. This raceway surface profile increases lubrication performance.