Variable-Tow Braided Covers for Propeller Blade Core Fit
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Solution Overview
Problem
Existing braiding processes for propeller blades face challenges in applying a braided cover that closely follows the shape of a variable perimeter core, particularly at the tip region, leading to excess material and discontinuities that affect strength and integrity while increasing costs.
Innovation Solution
The method involves varying properties of the tow, such as fiber composition, diameter, and linear weight along the length of the core, using bobbins configured to adapt the braided cover to the core's shape, and employing techniques like thermal bonding, knotting, or winding to join tow sections with varying properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a uniform tow configuration is used in braiding, then the braiding process is simple and efficient, but the braided cover cannot closely follow the shape of the variable perimeter core at the tip region
Solution Approach 1:
The patent applies local quality by varying the tow configuration (number of fibres, tow diameter, or linear weight) in different sections along the length of the tow. Specifically, the tow has a first configuration with higher fibre count/diameter/weight for the root region and a second configuration with lower fibre count/diameter/weight for the tip region, allowing the braided cover to closely follow the variable perimeter of the core at different locations.
Solution Approach 2:
The tow is segmented into different sections with distinct configurations. The tow comprises a first section with a first tow configuration and a second section with a second tow configuration, where the properties differ between sections. This segmentation allows different parts of the same tow to serve different functional requirements along the core length.
2Manufacturing precision
If excess braid material is used to ensure coverage, then adequate coverage of the cover is achieved, but material waste increases and cutting operations are required
Solution Approach 1:
The patent reduces material waste by applying local quality - the tow configuration is optimized for each region. By having more fibres/diameter in the root region and fewer fibres/smaller diameter in the tip region, the braided cover precisely matches the core perimeter at each location, eliminating the need for excessive material and subsequent cutting operations.
Solution Approach 2:
The patent changes the parameters of the tow (number of fibres, tow diameter, or linear weight) along its length to match the varying core perimeter. This parameter variation ensures that the braided cover fits the core shape accurately without requiring excess material that would need to be trimmed away.
3Manufacturing precision
If the tow properties are varied along the length, then the braided cover fits the core shape better, but the braiding process complexity increases
Solution Approach 1:
The complex requirement of varying tow properties is simplified through segmentation - the tow is divided into distinct sections (first section and second section) with defined configurations. This segmentation makes the manufacturing process more manageable by breaking down the continuous variation into discrete, controllable segments that can be produced using standard braiding equipment.
Data Source
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AI summary
A method of applying a braided cover (12) to a core (10) comprises braiding a plurality of tows (8) around the core (10) from a plurality of bobbins (6). One or more properties of the tow (8) on a respective bobbin (6) vary along the length of the tow (8).