Flow-Formed Aluminum Wheel Rim for Stronger Lightweight Wheels
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Solution Overview
Problem
Existing methods for producing aluminum alloy wheels, particularly using gravity casting, face challenges in enhancing the mechanical properties of the rim, such as slow solidification and potential defects.
Innovation Solution
A method involving gravity casting followed by a flow forming process and subsequent heat treatment (T6 process) to improve the mechanical properties of the rim, including a specific wall thickness ratio and composition of aluminum alloy with optimal silicon, magnesium, and other elements, to enhance tensile strength, proof stress, and elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If gravity casting technique is used to produce aluminum alloy wheels, then it is easy to form a hollow structure and reduce weight, but the solidification is slow and defects are likely to remain
Solution Approach 1:
The patent applies preliminary action by performing flow forming (plastic deformation) on the precursory rim before final solidification completes. This pre-deformation creates controlled stress that accelerates solidification and refines the grain structure, preventing defects while maintaining the hollow structure benefit of gravity casting
2Shape
If the precursory rim is drawn in first direction and second direction during flow forming, then the wing portions are reduced in thickness to form a thinner and wider rim portion, but the mechanical properties of the rim need to be adequately improved
Solution Approach 1:
The patent applies parameter changes by precisely controlling the wall thickness ratio (t1/t2) between 132-433% and specifying exact aluminum alloy compositions (Si: 5.0-7.5%, Mg: 0.40-0.90%). These parameter optimizations ensure that the rim achieves the desired thinner and wider shape while maintaining adequate mechanical properties through controlled plastic deformation and material composition
3Loss of substance
If wall thickness ratio t1/t2 is controlled within specific range, then material efficiency is optimized, but manufacturing precision is required
Solution Approach 1:
The patent applies parameter changes by establishing specific ranges for wall thickness ratio (t1/t2: 132-433%) and alloy composition (Si: 5.0-7.5%, Mg: 0.40-0.90%). These defined parameters provide clear manufacturing targets that optimize material efficiency while guiding precision control during the flow forming process
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 method effectively improves the mechanical properties of the wheel rim, achieving desirable tensile strength, proof stress, and elongation while optimizing material efficiency and reducing the likelihood of defects.
Implementation Method 1
step A of forming an intermediate product from an aluminum alloy by using a casting technique
Implementation Method 2
step B of performing a shear-forming operation as a flow forming process for the precursory rim of the intermediate product
Implementation Method 3
subsequent heat treatment (T6 process) to improve the mechanical properties of the rim
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method of producing a wheel for straddled vehicles (100) according to an embodiment of the present invention includes: step (A) of forming an intermediate product (110') including a precursory hub (110'), a precursory rim (120'), and plurality of precursory spokes (130') by using a gravity casting technique; step (B) of performing a flow forming process for the precursory rim of the intermediate product in which, while the intermediate product is rotated, at least a portion of the precursory rim is drawn in a first direction (D1) and a second direction (D2), the first direction (D1) being one direction that extends from a center on an axial direction, and the second direction (D2) being an opposite direction that extends from the center of the intermediate product on the axial direction; and step (C) of, after step (B), performing a cutting process for the intermediate product to at least complete the rim (120). A ratio of a wall thickness (t1) of the precursory rim after step (B) and before step (C) to a wall thickness (t2) of the rim after step (C) is not less than 132% and not more than 433%.