Wheel Bearing Outer Member Weight Reduction via Forged Ribs
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Solution Overview
Problem
Conventional automobile wheel bearing devices face challenges in reducing weight without compromising strength and stiffness, and are costly due to complex manufacturing processes, with increased stress at critical areas under moment loads.
Innovation Solution
The wheel bearing device features an outer member with a vehicle-body-mounting flange having discontinuous ears in the circumferential direction, tapered outer surface, and ribs formed by forging, which reduces weight without altering tapped hole lengths or contact area, and decreases stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the outer member uses a conventional solid structure, then strength and stiffness are maintained, but weight increases
Solution Approach 1:
The outer member employs a hollow cylindrical structure with an inner circumferential surface that forms a cavity. This hollow configuration reduces the amount of material required, thereby decreasing weight while preserving the structural strength and stiffness needed to support wheel loads and resist deformation during operation.
Solution Approach 2:
The outer member is divided into functional zones: a reinforced outer shell for strength, an inner hollow cavity for weight reduction, and strategically positioned ribs on the inner circumferential surface for localized stiffness enhancement. This segmentation allows optimization of each zone for its specific function while achieving overall weight reduction.
2Weight of moving object
If complex manufacturing processes are used to reduce weight, then weight decreases, but manufacturing cost increases
Solution Approach 1:
The hollow cavity and rib structures are formed during the initial forging or casting process of the outer member, rather than requiring subsequent machining or assembly operations. This preliminary formation of weight-reducing features integrates multiple functions into a single manufacturing step, reducing both weight and manufacturing cost.
Solution Approach 2:
The design combines the outer shell, inner cavity, and reinforcing ribs into a single integrated forged or cast component. This merging of multiple structural elements into one manufacturing operation eliminates the need for separate machining, welding, or assembly steps, thereby reducing manufacturing complexity and cost while achieving weight reduction.
3Weight of moving object
If material is removed to reduce weight, then weight decreases, but stress concentration increases at critical areas
Solution Approach 1:
The inner circumferential surface features ribs that are strategically positioned at locations subject to high stress concentrations during moment loading. These localized reinforcements provide additional structural support precisely where needed, allowing material to be removed from less critical areas for weight reduction while maintaining strength at stress-critical zones.
Solution Approach 2:
The ribs on the inner circumferential surface are designed with curved or rounded transitions rather than sharp corners, distributing stress more evenly across critical areas. This curvature eliminates stress concentration points that would otherwise occur at abrupt geometric changes, allowing aggressive weight reduction without compromising structural integrity under moment loads.
Data Source
AI summary
A wheel bearing device has a vehicle-body-mounting flange 5b with a plurality of ears 10 discontinuously formed in a circumferential direction on an outer circumferential surface of the outer member 5. An outer circumferential surface 11 on the outer side of the outer member is tapered and formed such that a diameter of the outer member gradually decreases in a direction to an outer side. Ridges 16 protrude from a fitting surface 12 toward the outside in a radial direction. The ridges 16 are formed between the plurality of ears 10. The ridges 16 are forged to smoothly connect to the outer circumferential surfaces of the plurality of ears 10. Ribs 15 are forged on inner-side outer circumferential surfaces of the plurality of ears 10.