Outer Ring Relief Surface for Bearing Creep and Breakage
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Solution Overview
Problem
Existing rolling bearings with relief surfaces on the outer ring are prone to breakage due to stress concentration and insufficient creep reduction, especially when fitted to a fixed member with a clearance fit, particularly when the fixed member is made of a light metal with low rigidity.
Innovation Solution
The outer ring is designed with a relief surface on its outer periphery, machined to a roughness of Ra 5.0 µm or less, and formed with a suitable relief surface angle (0.7θ ≤ α ≤ θ) to reduce creep and prevent breakage, while ensuring a radial gap and using a bearing steel with a hardness of HRC 60 to 65.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a relief surface is formed on the outer ring to reduce creep, then creep is reduced, but the outer ring becomes more prone to breakage due to stress concentration
Solution Approach 1:
The relief surface is designed with specific local characteristics (roughness Ra 5.0 µm or less, specific angle range 0.7θ ≤ α ≤ θ) to create optimal stress distribution. The surface is machined with controlled roughness and specific geometric parameters to reduce creep while minimizing stress concentration, applying local quality modifications rather than uniform changes throughout the outer ring structure.
Solution Approach 2:
The invention changes critical parameters of the relief surface including roughness (Ra 5.0 µm or less), angle (0.7θ ≤ α ≤ θ), and radial gap dimensions. By optimizing these parameters, the relief surface effectively reduces creep while the controlled roughness and geometric constraints prevent excessive stress concentration that would lead to breakage.
2Ease of operation
If the outer ring is fitted to the housing with a clearance fit for easy mounting, then ease of mounting is improved, but creep occurs causing circumferential displacement
Solution Approach 1:
The relief surface is pre-formed on the outer ring with specific geometric characteristics before the bearing is installed. This preliminary structural modification ensures that when the bearing is mounted with clearance fit, the relief surface is already positioned to counteract creep forces from the outset, preventing circumferential displacement during operation.
Solution Approach 2:
The relief surface creates a localized structural feature on the outer ring that specifically addresses creep in the load application region. This local quality modification allows the majority of the outer ring to maintain clearance fit for easy mounting, while the specific region with the relief surface provides enhanced stability against circumferential displacement.
3Stability of the object's composition
If the relief surface angle is increased to improve creep reduction, then creep reduction is improved, but the outer ring becomes more thin-walled and weaker
Solution Approach 1:
The invention optimizes the relief surface angle within a specific range (0.7θ ≤ α ≤ θ) to achieve the best balance between creep reduction and structural strength. This parameter optimization ensures the relief surface is sufficiently aggressive to reduce creep while maintaining adequate wall thickness and structural integrity of the outer ring.
Solution Approach 2:
The relief surface geometry is designed with specific copied dimensions and angles that have been optimized through analysis. The angle copying from theoretical optimal values (within the range 0.7θ ≤ α ≤ θ) ensures effective creep reduction while maintaining strength, replicating the optimal geometric configuration across the relief surface.
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 solution effectively reduces creep and prevents breakage of the outer ring, even when fitted to a fixed member made of a light metal, by distributing load evenly and maintaining structural integrity.
Implementation Method 1
the mechanism of the creep of the bearing rings (outer ring and inner ring) of the rolling bearing, it has been known that traveling waves generated on the surfaces of the bearing rings move the bearing rings
Implementation Method 2
an unbalanced load on the shaft under load or during high-speed rotation may cause creep, so that the outer ring is circumferentially displaced with respect to the housing
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A rolling bearing (1) is provided in which an outer ring (2) has, on its outer periphery, a fitting surface (2b) fitted to a housing (10) as a fixed member, and a relief surface (2c) separating the fitting surface (2b) over the entire width of the fitting surface (2b), and opposed to the inner peripheral surface (10a) of the housing (10) with a radial gap larger than the radial gap between the fitting surface (2b) and the inner peripheral surface (10a). The relief surface (2c) is machined to have a roughness of Ra 5.0 µm or less.