Composite Bicycle Rim Spoke Seats With Continuous Fiber Reinforcement
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Solution Overview
Problem
Existing composite bicycle wheel rims suffer from structural weakening due to areas with only polymeric material and air bubbles around perforated spoke-attachment seats, and the fibers are not fully stretched, leading to delayed response to mechanical stresses during use.
Innovation Solution
The rim design features areas with both continuous and cut structural fibers around each perforated seat, ensuring proper fiber distribution and alignment before molding, which enhances the rim's ability to withstand mechanical stresses by maintaining fiber continuity and preventing polymeric material deficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a not-cutting pointed tool is used to displace structural fibers before molding, then the fibers are not cut and continuity is maintained, but areas with only polymeric material and air bubbles are formed around perforated seats, causing structural weakening
Solution Approach 1:
The tool is segmented into two distinct functional parts: a conical cutting tip for initial hole formation and a cylindrical non-cutting portion for fiber displacement. This segmentation allows the tool to perform both cutting and displacement functions in sequence, resolving the contradiction between maintaining fiber continuity and avoiding polymeric material deficiencies.
Solution Approach 2:
The conical cutting tip performs preliminary action by creating an initial hole and displacing fibers before the molding process. This preliminary cutting action prevents the formation of areas with only polymeric material, while the subsequent non-cutting portion maintains fiber continuity during displacement, thereby resolving the structural weakening issue.
2Manufacturing precision
If structural fibers are displaced before molding, then perforated seats are formed in desired positions, but the fibers are not fully stretched, leading to delayed response to mechanical stresses
Solution Approach 1:
The tool parameters are optimized to achieve both precise positioning and fiber stretching. The conical tip geometry and insertion depth are controlled to displace fibers to the exact position needed for spoke attachment while simultaneously stretching them sufficiently to ensure immediate stress response, resolving the contradiction between positioning accuracy and stress response reliability.
3Ease of manufacture
If a cutting tool is used to create perforated seats, then holes are formed in the composite material, but structural fibers are cut or sheared, creating areas with only polymeric material
Solution Approach 1:
The tool is segmented into a cutting tip for hole formation and a non-cutting cylindrical portion for displacement. This segmentation allows easy hole formation through the cutting action while preventing excessive fiber cutting that would create polymeric material deficiencies, thereby resolving the contradiction between manufacturing ease and rim strength.
Data Source
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AI summary
The invention relates to a bicycle wheel rim, comprising a wall made of composite material having a plurality of perforated spoke-attachment seats (58), wherein each perforated seat (58) is delimited by at least one first area (62) comprising an amassment of continuous structural fibers (60) and at least one second area (64) circumferentially spaced apart from said first area (62) and comprising cut structural fibers (60). The invention also relates to a process for manufacturing the aforementioned rim.