Variable-Thickness Wheel Rim for Lower Mass and Stress
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Solution Overview
Problem
Conventional vehicle wheel rims made by flow forming lack optimization in material usage, resulting in higher mass and increased stress levels due to uniform thickness across the rim, which is not necessary for all structural areas.
Innovation Solution
The rim is designed with a well portion featuring multiple transition portions of varying thickness cross-sectional profiles, formed through a combination of flow forming and rolling processes, to reduce material usage and stress levels by varying thicknesses across the rim's length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a uniform thickness profile is used across the rim, then the rim has sufficient structural rigidity, but the overall mass of the wheel increases and material usage is not optimized
Solution Approach 1:
The rim is designed with non-uniform thickness distribution, where the well portion has reduced thickness compared to other areas. This local variation in geometry allows mass reduction in areas where full thickness is not required, while maintaining sufficient structural rigidity in critical regions through the optimized thickness profile that includes multiple transition portions.
Solution Approach 2:
The well portion of the rim is divided into multiple segments including a first well portion, second well portion, third well portion, and fourth well portion, each with different thickness characteristics. This segmentation allows for optimized material distribution across different functional zones of the rim, reducing overall mass while maintaining structural integrity through carefully designed transition zones between segments.
2Ease of manufacture
If uniform thickness is maintained across the rim, then manufacturing is simpler, but stress levels increase and material usage is inefficient
Solution Approach 1:
The rim incorporates localized thickness variations with multiple transition portions that gradually change the cross-sectional profile. This local quality variation reduces stress concentrations by avoiding abrupt thickness changes, while the progressive transition design maintains manufacturing feasibility through controlled geometric changes that can be achieved through standard forming processes.
3Weight of moving object
If the well portion is thinned to reduce mass, then material usage is optimized, but structural rigidity may be compromised
Solution Approach 1:
The well portion is segmented into four distinct sections (first, second, third, and fourth well portions) with progressively varying thicknesses. This segmentation allows mass reduction in non-critical areas while maintaining sufficient rigidity in regions where structural support is needed, with transition portions connecting these segments to ensure smooth stress distribution.
Solution Approach 2:
The rim thickness variation is implemented in the radial dimension, creating a multi-dimensional thickness profile rather than a uniform single-dimension design. The transition portions use curved geometries that smoothly vary thickness in the radial direction, optimizing the balance between mass reduction and structural rigidity by distributing material where it provides maximum structural benefit.
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 design reduces the overall weight of the wheel while maintaining structural rigidity by strategically thinning areas where reduced mass and stress are acceptable, improving the rim's efficiency and performance.
Implementation Method 1
Flow forming is basically a metal-forming technique in which a metallic workpiece is formed over a mandrel by one or more rollers using pressure along the axial direction. The roller deforms the workpiece, forcing it against the mandrel, both axially lengthening and radially thinning it.
Data Source
AI summary
A vehicle wheel includes an annular rim defining an axis and inboard and outboard sides. The rim includes an outboard bead seat, an inboard bead seat, an outboard well flank connected to the outboard bead seat and extending radially inwardly and towards the inboard side of the rim, and an inboard well flank connected to the inboard bead seat and extending radially inwardly and towards the outboard side of the rim. The rim further includes a well portion defined between the outboard and inboard well flanks, wherein the well portion is formed by a plurality of curved and straight portions linked together. The well portion has at least three transition portions having varying thickness cross-sectional profiles. A wheel disc is secured to the rim. The wheel disc includes a hub located centrally within the wheel disc and has a plurality of bolt holes formed therein.