Pneumatic Tyre Cord Combining Cellulose and Nylon Fibers
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Solution Overview
Problem
Cellulose fibers used in tire carcass plies, such as rayon and lyocell, exhibit inferior fatigue resistance, leading to fatigue fractures and reduced durability, particularly when used at angles of 80° to 90° with respect to the tire circumferential direction.
Innovation Solution
A cord combining highly rigid cellulose fibers with fatigue-resistant nylon fibers, where the ply twist number of cellulose is set to be greater than that of nylon, ensuring that the nylon fibers absorb the majority of compressive strain, thereby enhancing the fatigue resistance of the cord.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly rigid cellulose fiber is used in the cord, then steering stability is improved, but fatigue resistance deteriorates
Solution Approach 1:
The patent applies composite materials by combining cellulose fiber and nylon fiber in a single cord. The cellulose fiber provides high rigidity for steering stability, while the nylon fiber contributes excellent fatigue resistance. This composite structure allows the cord to simultaneously achieve both high rigidity and high fatigue resistance, resolving the technical contradiction between these two properties.
2Reliability
If the carcass is placed at an angle of 80° to 90° with respect to the tire circumferential direction to reduce fretting wear, then fatigue resistance is improved, but compressive strain on cords increases leading to lower durability
Solution Approach 1:
The composite cord structure enables the tire to use steeper carcass angles (80°-90°) without durability loss. The nylon fiber component absorbs compressive strain through its elastic properties, protecting the cellulose fiber from damage while maintaining high fatigue resistance. This resolves the contradiction by allowing the beneficial angle configuration without the harmful compressive strain effects.
Solution Approach 2:
The patent changes the material parameters of the cord by incorporating nylon fiber with different mechanical properties (higher elasticity and fatigue resistance) compared to pure cellulose fiber. This parameter change allows the cord to withstand compressive strain at steep angles, enabling the optimization of carcass angle for fatigue resistance without sacrificing durability.
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 combined cord achieves improved fatigue resistance and durability while maintaining high rigidity, allowing the tire carcass to be positioned at angles between 60° and 90° with respect to the tire circumferential direction, resulting in enhanced steering stability and durability.
Implementation Method 1
nylon fiber having excellent fatigue resistance mixed in with highly rigid cellulose fiber... the nylon fibers absorb the majority of compressive strain, thereby enhancing the fatigue resistance of the cord
Data Source
Figure 1~2
Figure 3
AI summary
A cord for reinforcing rubber articles according to the present invention is formed by a thread with ply-twisted cellulose fiber twisted with a thread of ply-twisted nylon fiber. The ply twist number of the nylon fiber is less than the ply twist number of the cellulose fiber. A pneumatic tire according to the present invention uses the cord for reinforcing rubber articles according to the present invention in a ply cord of the carcass.