Helical Tennis Racket String Core with Natural Filaments
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Solution Overview
Problem
Existing methods for incorporating natural silk filaments into tennis racket strings are difficult to industrialize and result in cores that lack the necessary characteristics for effective use as racket strings, with existing thermoplastic polymer matrices either damaging the filaments at high temperatures or failing to provide adequate impregnation at lower temperatures.
Innovation Solution
A core for a tennis racket string featuring a thermoplastic matrix with a viscosity suitable for extrusion at temperatures below 130°C, where the matrix is helically twisted and comprises natural origin filaments twisted in opposite directions, allowing for the use of polyamide or polyurethane materials and a pretreatment process with a solvent to ensure impregnation without damaging the filaments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thermoplastic polymer matrix is used to encapsulate silk filaments, then the core gains structural integrity and cohesion, but the high temperature required for processing damages the natural silk filaments
Solution Approach 1:
The patent changes the temperature parameter of the thermoplastic matrix to below 130°C, which is below the damage threshold of silk filaments. This allows the matrix to be processed at temperatures that preserve the integrity of the natural filaments while still achieving adequate viscosity for impregnation and encapsulation.
Solution Approach 2:
The patent creates a composite structure where thermoplastic matrix material encapsulates natural silk filaments. The matrix provides structural integrity and cohesion to the core, while the natural filaments provide strength and elasticity. The composite achieves both structural requirements without thermal damage to the sensitive natural components.
2Manufacturing precision
If the thermoplastic matrix viscosity is reduced for better impregnation of filaments, then the matrix can penetrate the filaments more effectively, but the material becomes too fluid to maintain structural integrity
Solution Approach 1:
The patent optimizes the viscosity parameter of the thermoplastic matrix to a specific range that allows adequate impregnation of filaments while maintaining sufficient structural integrity. The viscosity is controlled to be low enough for penetration but high enough to preserve core strength and cohesion.
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 solution enables the production of a racket string core with enhanced mechanical strength and cohesion, suitable for industrial-scale manufacturing while preserving the natural properties of the silk filaments, ensuring the filaments are not damaged during processing and achieving effective impregnation.
Implementation Method 1
a thermoplastic material with a melting temperature lower than the deterioration temperature of the threads
Implementation Method 2
the viscosity allows a satisfactory impregnation of the threads
Data Source
AI summary
This core (2) for a racket string, in particular for a tennis racket string, includes a thermoplastic matrix (24) in which filaments (22) are embedded, at least one of these filaments being of natural origin and the thermoplastic matrix (24) being made of a material which, at a temperature lower than a threshold temperature, at which the filaments (22) are not substantially damaged, has a viscosity making it suitable for an extrusion process. The matrix (24) includes a plurality of strands that are helically twisted in a first direction, each of the strands including a plurality of filaments (22) of natural origin that are helically twisted in a second direction, which is or is not opposite to the first direction.