Motorcycle Wheel Rim Flow Forming Without Clamp Scars
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Solution Overview
Problem
Existing methods for producing wheels for straddled vehicles, such as motorcycles, leave clamp scars due to the flow forming process, which compromises the aesthetic value of both sides of the wheel.
Innovation Solution
A method involving a flow forming process that uses a flow forming apparatus with mandrels and a roller to deform the precursory rim, where the inner peripheral surface of the rim includes stepped portions that allow for clamping without relying on the hub or spokes, ensuring no clamp scars are left on the final product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flow forming process is performed for the intermediate product to reduce weight and improve material strength, then the weight of the wheel is reduced and material strength is improved, but clamp scars are left on the wheel compromising its aesthetic value
Solution Approach 1:
The patent divides the clamping function into two separate locations: the precursory rim and the precursory hub. By forming stepped portions on the inner peripheral surface of the precursory rim, the clamping force is applied at multiple locations rather than solely through the hub or spokes, preventing clamp scars on the design surfaces while still enabling the flow forming process to improve material strength
Solution Approach 2:
The stepped portions on the precursory rim act as an intermediary clamping surface between the mandrels and the intermediate product. This intermediary structure allows the flow forming apparatus to apply clamping force without directly contacting the hub or spokes that would otherwise be visible on the finished wheel, thus preventing clamp scars while maintaining the aesthetic value
2Ease of manufacture
If the precursory rim is clamped during flow forming to enable the process, then the flow forming can be performed, but clamp scars are left on the hub or spokes
Solution Approach 1:
The stepped portions are formed on the precursory rim before the flow forming process begins. This preliminary action creates dedicated clamping surfaces that are specifically designed to receive the mandrels during flow forming, enabling the manufacturing process while preventing damage to the aesthetic surfaces of the hub and spokes
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 produces a wheel for straddled vehicles without clamp scars, maintaining aesthetic integrity while enhancing mechanical properties like tensile strength and proof stress through a combination of gravity casting and flow forming, with specific aluminum alloy compositions.
Implementation Method 1
a gravity casting step of casting an intermediate work that includes a precursory disc and a precursory rim by gravity casting
Implementation Method 2
a plastic processing step of performing a plastic processing (which also involves thinning) for the precursory rim of the intermediate work to form a rim
Implementation Method 3
Specifically, as the plastic processing at the plastic processing step, a flow forming process is performed
Data Source
Figure 1~2
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AI summary
A method of producing a wheel for straddled vehicles (100) according to an embodiment of the present invention includes: step (A) of providing an intermediate product (100') including a precursory hub (110), an annular precursory rim (120), and a plurality of precursory spokes (130), the intermediate product (100') being made of a metal material; and step (B) of performing a flow forming process for the precursory rim of the intermediate product by using a flow forming apparatus (10). The flow forming apparatus (10) includes: a first mandrel (21); a second mandrel (22); a rotating mechanism (31) to rotate the first and second mandrels; and a roller (41) to be pressed against an outer peripheral surface (120b') of the precursory rim. The inner peripheral surface of the precursory rim of the intermediate product includes a first region (R1) that abuts with a first abutting surface (21a) of the first mandrel and a second region (R2) that abuts with a second abutting surface (22a) of the second mandrel. Each of the first and second regions includes at least one stepped portion (121) protruding inwardly along a radial direction of the intermediate product.