Bearing Rolling Component Surface Treatment for Inclusion Cracks
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Solution Overview
Problem
Non-metallic inclusions on the surface of rolling components can lead to premature failure of bearings due to gaps forming between the inclusions and the base material, which act as open cracks, especially when the fiber flow and raceway surface form a large angle.
Innovation Solution
The rolling component's surface is polished and then plastically worked to achieve an Ra of 0.1 μm or less, an Rsk<0, and a compressive residual stress of 700 MPa or more, with the fiber flow forming an angle of 15° or more, thereby reducing the gap between the non-metallic inclusion and the base material, preventing the gap from acting as an open crack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fiber flow and raceway surface form a large angle to accommodate product shape requirements, then the adaptability to product shape is improved, but the non-metallic inclusion is more likely to be exposed at the raceway surface causing premature failure
Solution Approach 1:
The patent changes the surface roughness parameter (Ra to 0.1 μm or less) and introduces compressive residual stress (700 MPa or more) through plastic working. These parameter changes suppress the exposure of non-metallic inclusions and prevent gap formation, allowing the fiber flow to form a larger angle (15° or more) with the raceway surface while maintaining bearing reliability.
2Manufacturing precision
If the surface is highly polished to reduce roughness, then the surface finish is improved, but the gap between non-metallic inclusion and base material remains and acts as an open crack
Solution Approach 1:
The patent applies plastic working (such as roller burnishing) after polishing to preliminarily compress the surface layer and fill gaps between non-metallic inclusions and the base material. This preliminary action creates compressive residual stress that prevents the gaps from acting as open cracks during bearing operation, thereby maintaining reliability while achieving high surface finish.
3Reliability
If steel making methods are used to eliminate non-metallic inclusions, then the purity of the steel material is improved, but the cost increases and the material is not readily available
Solution Approach 1:
The patent converts the harmful presence of non-metallic inclusions into a beneficial outcome by using plastic working to compress the surface layer and fill gaps around inclusions. The inclusions themselves remain, but their harmful effect is neutralized by the compressive residual stress that prevents gap formation and crack initiation, thereby maintaining reliability without requiring expensive ultra-clean steel.
4Manufacturing precision
If roller burnishing is applied to pulverize non-metallic inclusions, then the grain size of inclusions is reduced, but the inclusions are not completely eliminated and gaps may still form
Solution Approach 1:
The patent applies plastic working with controlled parameters (compressive residual stress of 700 MPa or more, surface Ra of 0.1 μm or less) to fundamentally change the surface state. This approach doesn't just reduce inclusion size but prevents gap formation through compressive stress, providing a more reliable solution than merely pulverizing inclusions while maintaining their presence.
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 approach effectively fills the gap between the non-metallic inclusion and the base material, suppressing the extension of cracks and enhancing the rolling fatigue life of the bearing, even when the angle between the fiber flow and raceway surface is 15° or more, thus increasing the bearing's durability and lifespan.
Implementation Method 1
the surface is plastically worked to achieve an Ra of 0.1 μm or less, an Rsk<0, and a compressive residual stress of 700 MPa or more
Data Source
AI summary
A rolling component has a surface. The rolling component includes a fiber flow. The surface has an Ra of 0.1 μm or less, an Rsk<0, and a compressive residual stress of 700 MPa or more. The surface and the fiber flow form an angle of 15° or more.