Hard-Rolled Bearing Raceway for Higher Static Load Capacity
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Solution Overview
Problem
Existing methods for increasing the load capacity of surface-hardened rolling bearing raceways either compromise the dynamic load capacity or fail to effectively enhance the static load capacity, leading to reduced service life.
Innovation Solution
A method involving hard rolling with rolls of specific diameters (8 to 25 times the surface hardening depth) and controlled surface pressures (2000 MPa to 3300 MPa) to reduce residual tensile stresses in the core region, combined with machining to remove surface structure changes, which minimizes plastic deformations and maintains material integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high surface pressure (3500-5500 MPa) is used during rolling to increase static load capacity, then the residual tensile stress maximum is reduced and static load capacity increases, but the dynamic continuous load capacity decreases and service life is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface pressure within the range of 2000-3300 MPa during rolling, and by selecting roll diameters in the range of 8 to 25 times the surface hardening depth. This optimized parameter combination reduces residual tensile stresses in the core region while minimizing plastic deformations in the hardened outer layer, thereby increasing static load capacity without compromising dynamic load capacity and service life
2Manufacturing precision
If the roll diameter is small to achieve high surface pressure, then the hardened outer layer is effectively treated, but excessive plastic deformations occur in the core region reducing service life
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing an optimal relationship between roll diameter and surface hardening depth. By specifying that the roll diameter should be 8 to 25 times the surface hardening depth, the process achieves effective surface treatment while distributing the plastic deformations over a larger volume, preventing excessive localized deformations in the core region that would compromise service life
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 enhances the static load capacity while preserving the dynamic load capacity and service life of the rolling bearing raceways by carefully managing residual stresses and plastic deformations.
Implementation Method 1
a surface pressure prevailing in the rolling contact between the roll and the rolling bearing raceway during the hard rolling being set in the range between 2000 MPa and 3300 MPa
Implementation Method 2
load stresses brought about in the unhardened core region are at most 0.9 to 2 times, preferably 1.2 to 1.5 times, the yield strength S of the unhardened core region K
Data Source
AI summary
A rotor bearing having a rolling bearing raceway in an unhardened core region of a rolling bearing ring element that further includes an outer layer hardened to a surface hardening depth wherein the rolling bearing raceway is formed by a roll, wherein a diameter of the roll is 8 to 25 times the surface hardening depth.