Hard-Rolled Bearing Raceway for Higher Static Load Capacity
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Solution Overview
Problem
Existing methods for increasing the load-bearing capacity of surface-hardened rolling bearing raceways either reduce the dynamic long-term load capacity or fail to effectively enhance the static load-bearing capacity, leading to a shorter service life.
Innovation Solution
A method involving hard rolling of the rolling bearing raceway with a roller diameter between 8 to 25 times the edge hardening depth, using surface pressures between 2000 MPa and 3300 MPa, followed by machining to remove surface structure changes, which minimizes plastic deformations and reduces internal tensile stresses, thereby increasing the static load-bearing capacity while maintaining dynamic load capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high surface pressure (3500-5500 MPa) is used during hard rolling, then static load-bearing capacity increases, but dynamic fatigue load capacity decreases
Solution Approach 1:
The patent applies parameter changes by optimizing the surface pressure range to 2000-3300 MPa (specifically 2300-2800 MPa) and selecting roller diameters 8-25 times the surface hardening depth. This parameter optimization achieves deep penetration of compressive residual stresses to reduce core tensile stresses while minimizing excessive plastic deformation that would harm dynamic fatigue performance
Solution Approach 2:
The patent employs multiple rolling passes (1-100 passes, particularly 2-10 passes) to gradually build up compressive residual stresses. This dynamic, incremental approach allows the material to adapt progressively, achieving deep stress penetration without causing excessive localized plastic deformation that would reduce dynamic load capacity
2Strength
If deep plasticization is induced in the core area, then maximum residual tensile stress is reduced, but microcracks occur earlier under dynamic loading
Solution Approach 1:
The patent optimizes surface pressure (2000-3300 MPa) and roller diameter (8-25 times hardening depth) to achieve deep penetration of compressive stresses into the core area, effectively reducing maximum tensile stresses without causing excessive plastic deformation that would lead to microcrack formation
Solution Approach 2:
The patent applies partial plasticization through controlled rolling passes (1-100 passes) that generate sufficient compressive residual stresses to reduce core tensile stresses, but stops before excessive plastic deformation occurs. This partial action achieves the necessary stress redistribution while preserving material integrity and preventing premature microcrack initiation
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 method effectively increases the static load-bearing capacity and service life of the rolling bearing raceway by reducing internal tensile stresses and minimizing plastic deformations, while maintaining the dynamic load capacity, thus providing a compromise between material processing and stress reduction.
Implementation Method 1
the plasticization in the core area of the rolling bearing ring element caused by the known surface pressures in the range of 3,500 to 5,500 MPa contributes particularly effectively to a reduction of the maximum residual tensile stress
Implementation Method 2
a surface pressure prevailing in the rolling contact between the roller and the rolling bearing raceway during hard rolling is set in the range between 2000 MPa and 3300 MPa
Data Source
Figure 1~2
Figure 3~4c
Figure 5a~6
AI summary
The invention relates to a method for increasing the load-bearing capacity of a surface-hardened rolling-bearing raceway of a rolling-bearing ring element, comprising - providing a rolling-bearing ring element which has an unhardened core region (K) and, at least in certain portions, a surface layer (Ra) hardened to a surface-hardening depth (Rht), wherein a rolling-bearing raceway is formed in the region of the hardened surface layer (Ra), - hard rolling the rolling-bearing raceway using a roller, wherein the diameter of the roller is chosen in the range of 8 to 25 times the surface-hardening depth (Rht), - a level of surface pressing that prevails in the rolling contact between the roller and the rolling-bearing raceway during the hard rolling process is set in the range between 2000 MPa and 3300 MPa and - after being hard rolled, the rolling-bearing raceway is machined, and the invention also relates to a rolling device for hard rolling a surface-hardened rolling-bearing raceway of a rolling-bearing ring element.