Flanged Bearing Ring with Sealed Bimetallic Interface
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Solution Overview
Problem
Conventional flanged bearing rings with different material interfaces, such as steel and lightweight metals, face issues like differential thermal expansion, galvanic corrosion, and fretting due to material mismatch, leading to potential failure under load and thermal stress.
Innovation Solution
A flanged bearing ring design incorporating a radially inner steel core and a radially outer lightweight body with an annular gasket in a groove to create a hermetic seal, preventing material separation and corrosion, using semi-solid casting or other forming processes to interlock the components and enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a flanged bearing ring is made with a steel core and lightweight outer body joined together, then weight reduction is achieved, but the interface between materials becomes weak and prone to separation
Solution Approach 1:
The groove for receiving the sealing element is formed in advance during the casting process, before the bearing ring is put into service. This preliminary formation of the sealing groove ensures proper fit and sealing capability from the start, preventing interface separation before it can occur during operation.
Solution Approach 2:
A sealing element (intermediary component) is introduced between the steel core and lightweight outer body to prevent direct contact and separation at the material interface. This sealing element fills the groove and creates a hermetic seal that maintains the integrity of the bimetallic structure under thermal and mechanical stresses.
2Weight of moving object
If different materials (steel and lightweight metal) are used in the bearing ring, then weight is reduced, but differential thermal expansion causes micro-cracks and corrosion
Solution Approach 1:
The sealing element acts as an intermediary that isolates the interface between steel and lightweight metal from contaminants. By creating a hermetic seal in the groove, it prevents water, salt, and dust from penetrating the interface, thereby preventing galvanic corrosion and allowing the different materials to expand differently without causing micro-cracks.
Solution Approach 2:
The sealing element creates a protected, inert environment at the material interface by excluding moisture and contaminants. This inert barrier prevents electrochemical reactions between the dissimilar metals, eliminating galvanic corrosion despite the considerable difference in electrochemical potential between steel and lightweight alloy.
3Ease of manufacture
If the interface between steel core and lightweight body is left open, then manufacturing is simpler, but contaminants cause fretting and failure
Solution Approach 1:
A flexible sealing element (thin film structure) is placed in the groove to create a hermetic seal at the interface. This sealing film is simple to install and effectively blocks contaminants from reaching the material interface, preventing fretting and corrosion while maintaining manufacturing simplicity.
Solution Approach 2:
The sealing element serves as an intermediary barrier that protects the interface from contaminants. By introducing this single sealing component, the design achieves both manufacturing simplicity and high reliability, as the seal prevents water, salt, and dust from causing fretting and corrosion at the steel-lightweight metal interface.
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 provides a reliable, long-lasting, and watertight connection between the steel core and lightweight outer body, reducing the risk of fretting and failure by sealing the interface and minimizing thermal expansion differences, thus ensuring enhanced durability and safety.
Implementation Method 1
an annular gasket in a groove to create a hermetic seal, preventing material separation and corrosion
Implementation Method 2
The second material is joined to the first material by a semi-solid casting process
Implementation Method 3
repeated cycles of thermal stresses cause a differential thermal expansion between the outer body made of aluminium and the steel core, which has a coefficient of thermal expansion lesser than that of aluminium alloys
Implementation Method 4
there is a risk that the coupling between the outer body of light alloy and steel core deteriorates, resulting in fretting (sliding) and possibly failure of the flanged ring
Data Source
AI summary
A flanged bearing ring (10) for the wheel of a motor vehicle includes two different materials joined as a single piece: a tubular core (15) and an outer body (16) around the core. The outer body forms a radial flange (17) and is made of a lighter material than that of the core. At the axially outer end of the ring, at the side where the flange (17) is provided, the interface surfaces between the outer body (16) and the core (15) terminate in a groove (21) formed partly in the outer body and partly in the core. The groove (21) accommodates a sealing ring (22) made of rubber-like or elastomeric material which presses against both the outer body (16) and the core (15) so as to seal continuously, along an entire circumference around the axis (x), a separation line (23) between the core (15) and the outer body (16).