Bearing Ring Heat Treatment for Uniform Tempering of Variable Thickness
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Solution Overview
Problem
The existing heat treatment methods for bearing rings, particularly those with varying thickness in the axial direction, face challenges in achieving uniform heating, which can lead to uneven heating and reduced rolling fatigue life, especially in larger diameter bearings.
Innovation Solution
A heat treatment method involving a quenching process followed by a tempering process where the work is divided into blocks based on thickness, with inductive heating and cooling in a liquid bath, ensuring the internal temperature exceeds the surface temperature, and using an injection nozzle to concentrate cooling liquid on the raceway surface for enhanced cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quenching process followed by conventional inductive heating is applied to a bearing ring with varying thickness, then the bearing ring can be heat treated, but uneven heating occurs due to thickness variation, leading to insufficient improvement in rolling fatigue life
Solution Approach 1:
The bearing ring is divided into multiple heating zones along the axial direction, with each zone corresponding to a different thickness region. Each zone is equipped with independent heating control that adjusts heating parameters according to the local thickness, ensuring uniform heating across the entire bearing ring despite thickness variations.
Solution Approach 2:
Different heating conditions are applied to different axial positions of the bearing ring based on local thickness. Thinner sections receive lower heating power or shorter heating times, while thicker sections receive higher power or longer heating times, achieving uniform temperature distribution throughout the workpiece.
2Reliability
If the raceway surface is hardened to improve rolling life, then the bearing performance is enhanced, but the heat treatment cost increases due to the lengthy carbonitriding process required
Solution Approach 1:
The conventional carbonitriding process is replaced with a quenching process followed by inductive heating. This substitution eliminates the lengthy carbonitriding step while achieving the desired hardening effect through rapid cooling and controlled reheating, significantly reducing total heat treatment time.
Solution Approach 2:
The bearing ring undergoes phase transition during quenching, where rapid cooling transforms the microstructure to martensite, providing hardening. Subsequent inductive heating controls the phase transformation to achieve the desired surface hardness and internal stress distribution, replacing the time-consuming carbonitriding process.
3Temperature
If inductive heating is applied to thick-section bearing rings, then heating can be achieved, but the variation in thickness causes uneven heating that prevents full improvement of rolling fatigue life
Solution Approach 1:
The heating system employs dynamic control where heating parameters (power, frequency, duration) are continuously adjusted based on real-time feedback from temperature sensors positioned at different axial locations. This dynamic adjustment compensates for thickness variations and maintains uniform temperature distribution throughout the heating process.
Solution Approach 2:
Temperature sensors monitor the actual temperature at various axial positions during inductive heating, and this feedback information is used to automatically adjust heating parameters. The control system increases heating power to thinner sections and reduces power to thicker sections, ensuring uniform heating despite geometric variations.
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 method ensures even heating and high compression residual stress on the raceway surface, significantly improving the rolling fatigue life of the bearing ring while maintaining cost-effectiveness.
Implementation Method 1
a tempering process to the work which is quenched to entirely soak the work in cooling liquid and inductively heat the work in a state that the work is soaked in the cooling liquid
Implementation Method 2
under a state that a flow of the cooling liquid is generated so as to collect the cooling liquid to a part in which a first raceway surface of the work is formed
Data Source
AI summary
In a heat treatment method for obtaining a bearing ring for an annular roller bearing whose thickness changes in an axial direction, the heat treatment method includes (A) applying a quenching process to a work which is annular, made of high carbon chromium bearing steel, and having a thickness changing in an axial direction, (B) applying a tempering process to the work which is quenched to entirely soak the work in cooling liquid and inductively heat the work in a state that the work is soaked in the cooling liquid, and (C) applying a finishing process to the work which is tempered.