Railway Roller Bearing Inner Ring Design for Axle Scar Prevention
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Solution Overview
Problem
Conventional roller bearings for railway car axles experience axle scars due to interference between the inner ring and the shaft, leading to fretting and abrasion, which is not effectively prevented by existing methods that reduce surface pressure or groove formation, resulting in potential accidents.
Innovation Solution
A roller bearing design with an inner ring featuring a thin-wall part and a thick-wall part, where the axial direction width of the thin-wall part is greater than the distance to the ridge line part, reducing surface pressure and preventing axle scars without forming grooves on the shaft, and incorporating a peripheral groove and notch for lubricant supply to prevent fretting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner ring is designed with a conventional uniform thickness, then the bearing has sufficient structural strength, but the ridge line part interferes with the axle when bending is generated, causing axle scars
Solution Approach 1:
The inner ring is designed with non-uniform thickness: a thin-wall part with smaller diameter direction thickness at the end face side and a thick-wall part with larger diameter direction thickness at the center side. This local variation in thickness allows the ridge line part to have reduced surface pressure and prevent axle scars, while the thick-wall part maintains sufficient bearing strength.
2Reliability
If a groove is formed in the outer peripheral surface of the axle to prevent interference, then the inner peripheral surface end can be protected from interference, but the processing cost of the axle increases
Solution Approach 1:
Instead of modifying the axle by forming grooves to prevent interference, the invention inverts the approach by modifying the inner ring structure itself. The thin-wall part design changes the contact characteristics at the ridge line part, reducing surface pressure and preventing interference without requiring any modifications to the axle, thus avoiding additional processing costs.
3Reliability
If the surface pressure of the ridge line part is reduced by cutting the shoulder part, then some protection against interference is provided, but the surface pressure reducing effect is small and scar generation is not satisfactorily prevented
Solution Approach 1:
The inner ring employs local quality variation with distinct thin-wall and thick-wall parts. The thin-wall part specifically positioned at the end face side creates a pronounced reduction in surface pressure at the ridge line part, providing effective protection against scar generation. This structured approach with clear geometric definitions offers superior surface pressure reduction compared to conventional shoulder part cutting methods.
Data Source
AI summary
A flange part of an inner ring member (11) used in a roller bearing has a thin-wall part (13) having a relatively small diameter direction thickness on its end face side, and a thick-wall part (14) having a relatively large diameter direction thickness on its center side, and an inner diameter surface has a contact part (15) fitted to a shaft at its center part, a non-contact part (16) apart from the shaft in a diameter direction at its outer edge, and a ridge line part (17) positioned on the boundary between the contact part (15) and the non-contact part (16). The axial direction width L1 of the thin-wall part (13) from an end face (12) of the inner ring member (11) and the axial direction distance L2 between the end face (12) and a ridge line part (17) of the inner ring member (11) have a relation of L1>L2.