Composite Bicycle Rim Cavity Structure for Automated Strength
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Solution Overview
Problem
Existing methods for manufacturing fibre composite bicycle rims face challenges such as limited stability and strength due to short fibre pieces, increased weight with thicker walls, high costs, and manual labor in prepreg methods, and inefficiencies in automated production.
Innovation Solution
A method involving the use of a fibre structure supported by a carrier layer, where fibre bundles are guided and attached by a machine to form a targeted fibre structure, reducing manual effort and parts, and using a filling unit to create a cavity within the rim body, which is then infused with matrix material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If short fibres are used for reinforcement in automated production, then mechanical and automated production with consistent manufacturing quality is achieved, but the stability and strength of the bicycle rims is limited
Solution Approach 1:
The fibre structure is segmented into a carrier layer and separately laid fibre bundles. The carrier layer provides a base structure while the fibre bundles are placed in specific patterns to optimize strength without requiring thick walls, resolving the contradiction between automated production and structural strength.
Solution Approach 2:
The invention uses a composite structure combining a carrier layer (which may be made of different materials) with fibre bundles arranged in specific patterns. This composite approach allows automated placement while achieving the structural integrity needed to avoid increasing wall thickness.
2Strength
If wall thickness is increased to improve stability and strength, then the structural integrity is improved, but the total weight of the bicycle rim increases
Solution Approach 1:
The fibre bundles are arranged with varying density and orientation in different regions of the rim structure. High-strength areas receive more concentrated fibre placement while lower-stress areas use fewer fibres, achieving overall structural integrity without uniformly increasing wall thickness and weight.
Solution Approach 2:
Instead of increasing strength by adding material in the thickness dimension, the invention distributes fibre bundles in two-dimensional patterns on the carrier layer surface, creating strength through geometric arrangement rather than volumetric increase, thus avoiding weight penalty.
3Manufacturing precision
If prepregs are used to achieve suitable local wall thickness and high quality, then manufacturing quality and resilience are improved, but the cost increases and manual effort is required
Solution Approach 1:
The carrier layer serves multiple functions: it provides a base structure, acts as a template for fibre bundle placement, and can remain as part of the final composite structure. This self-service approach eliminates the need for separate draping operations and reduces manual labor while maintaining manufacturing precision.
Solution Approach 2:
The manual draping process is replaced by a machine-guided system that automatically places fibre bundles onto the carrier layer according to predetermined patterns. This mechanical substitution eliminates manual effort while maintaining or improving manufacturing precision and reduces material costs compared to expensive prepregs.
Data Source
AI summary
A method for making a bicycle rim, having a rim body with at least one integrated cavity . The cavity is enclosed by a component wall. The rim body extends in a rim plane over 360° transverse to its rotational axis.The cavity forms a chamber in the rim body. A plurality of component walls have two lateral rim flanks, a radial inner rim base and a radial outer rim well, which limit the chamber. A rim body support structure is formed by a fibre structure. A fibre bundle is attached to a carrier layer and passed reciprocally on the carrier layer to form a basic fibre layer of the fibre structure. The fibre structure is draped in a tool mould. A filling unit is placed in the tool mould so that the filling unit keeps the volume free for the cavity and the cavity is surrounded by the component wall.