Composite Bicycle Rim Braking Surface via Selective Matrix Removal
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Solution Overview
Problem
Bicycle wheel components made of composite materials face challenges in achieving good dry-weather and wet-weather braking performance while minimizing processing costs and complexity, and existing machining methods can damage the reinforcing fibers, leading to weakened rims and increased weight.
Innovation Solution
A process involving post-molding machining of bicycle wheel components, where only the polymeric material is removed from the braking area without damaging the structural fibers, using techniques like pyrolysis with a laser beam to create a surface with a reduced polymeric material layer and strategically placed grooves to enhance friction and water evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional machining methods are used to create braking surfaces on composite material rims, then braking performance is improved, but the reinforcing fibers are damaged leading to weakened rims
Solution Approach 1:
The patent replaces conventional mechanical machining methods (milling, grinding, abrasion) with a chemical etching process using concentrated nitric acid. This chemical substitution allows the polymeric matrix to be selectively removed to expose reinforcing fibers for braking contact, while the acid does not damage the fiber structure itself, thus maintaining rim strength while achieving functional braking surfaces
Solution Approach 2:
The patent changes the chemical parameters of the etching process by using concentrated nitric acid with specific concentration ranges (65-70% or 80-85%) and controlling etching time and temperature. These parameter adjustments enable selective removal of the polymeric matrix without compromising the reinforcing fibers, resolving the contradiction between creating braking surfaces and maintaining structural integrity
2Reliability
If conventional machining methods are used to create braking surfaces, then braking performance is improved, but processing costs and complexity increase
Solution Approach 1:
The patent replaces complex mechanical machining systems (milling machines, grinders, abrasion equipment) with a simple chemical etching process. This substitution dramatically reduces processing complexity and equipment requirements while achieving the same functional result of exposing reinforcing fibers for braking contact
Solution Approach 2:
The patent simplifies the manufacturing process by changing from multiple mechanical machining steps to a single chemical etching step with controllable parameters (acid concentration, time, temperature). This parameter-based approach reduces processing complexity while maintaining consistent braking surface quality
3Strength
If the polymeric material layer is thick, then structural integrity is maintained, but braking performance deteriorates
Solution Approach 1:
The patent applies local quality by selectively removing the polymeric matrix only in the braking surface regions through chemical etching, while leaving the bulk polymeric structure intact. This creates a localized braking surface with exposed reinforcing fibers for friction contact, while the rest of the rim maintains its original structural integrity with the full polymeric matrix
Solution Approach 2:
The chemical etching process enables precise local modification of the rim surface by selectively attacking the polymeric matrix in contact with the acid, exposing fibers only where needed for braking. This selective chemical action achieves local quality changes without compromising overall structural integrity
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 process results in improved braking performance in both dry and wet conditions with reduced noise and maintains the strength of the composite material, while keeping costs and complexity low, by optimizing the surface roughness and fiber exposure.
Implementation Method 1
using techniques like pyrolysis with a laser beam to create a surface with a reduced polymeric material layer
Data Source
AI summary
A process for manufacturing a bicycle wheel component, comprising the steps of providing a component having at least one braking area that cooperates with a braking body made by molding of composite material having structural fibers in a polymeric material, and post-molding machining of at least one region of the braking area by removing only polymeric material, without removal of the structural fiber, from the entire region so that the structural fiber outcrops at least in part from the polymeric material, and removing the structural fiber and possibly the polymeric material according to at least one groove within the region. A bicycle wheel component having a braking area of composite material, wherein in a region of the braking area, the structural fiber outcrops at least from the polymeric material, and the region comprises a groove through the structural fiber and possibly the polymeric material of the composite material.