Rubber Reinforcement Cord Twist Configuration
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Solution Overview
Problem
Conventional cords for rubber reinforcement suffer from inadequate bending fatigue resistance due to cracks in the adhesive layer, which leads to stress concentration and eventual destruction, while increasing final twists compromises dimensional stability and tensile strength.
Innovation Solution
A cord design featuring a core strand with a higher number of primary twists and a peripheral strand with a greater number of final twists, where the direction of final twist matches the primary twist, and alternating S and Z directions for the peripheral strands, reduces shear force on the adhesive layer, enhancing bending fatigue resistance without compromising dimensional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of final twists is increased to reduce shear force on the adhesive layer, then bending fatigue resistance is improved, but dimensional stability deteriorates and tensile strength decreases
Solution Approach 1:
The patent applies different twist characteristics to different parts of the cord structure. The core strand has a specific number of twists while the peripheral strands have a different number of twists. This local differentiation allows the core to provide structural stability while the peripheral strands reduce shear force through optimized twist direction matching, resolving the contradiction between bending fatigue resistance and dimensional stability.
Solution Approach 2:
The patent introduces asymmetry in the twist directions between core and peripheral strands. The peripheral strands are configured with twist directions that match their primary twist directions, creating an asymmetric twist pattern that differs from conventional symmetric designs. This asymmetric configuration optimizes stress distribution during bending while maintaining overall cord stability.
2Reliability
If the number of final twists is increased to reduce shear force on the adhesive layer, then bending fatigue resistance is improved, but tensile strength decreases
Solution Approach 1:
The patent applies different twist characteristics to different parts of the cord structure. The core strand has a specific number of twists while the peripheral strands have a different number of twists. This local differentiation allows the core to provide structural stability while the peripheral strands reduce shear force through optimized twist direction matching, resolving the contradiction between bending fatigue resistance and dimensional stability.
3Ease of manufacture
If the number of primary twists and final twists is limited in conventional cords, then manufacturing is simplified, but bending fatigue resistance is insufficient due to crack propagation in the adhesive layer
Solution Approach 1:
The patent changes the twist direction parameter of the peripheral strands to match their primary twist directions, rather than using conventional limited twist configurations. This parameter change optimizes the stress state during bending, preventing crack propagation in the adhesive layer while maintaining manufacturing feasibility through standardized twisting processes.
Data Source
AI summary
A cord for rubber reinforcement of the present invention includes a core strand including a plurality of strands (A), and a plurality of strands (B) disposed around the core strand. In the core strand, the plurality of strands (A) are finally twisted, and each of the plurality of strands (A) is formed of a plurality of reinforcing fibers (A) that are primarily twisted. Each of the plurality of strands (B) is formed of a plurality of reinforcing fibers (B) that are primarily twisted, and the plurality of strands (B) are finally twisted to be disposed around the core strand. The direction of final twist of the plurality of strands (B) is the same as the direction of primary twist in at least one strand (B) selected from the plurality of strands (B). The number of primary twists in the strand (B) is greater than the number of primary twists in the strand (A), and/or the number of final twists of the strands (B) is greater than the number of final twists of the strands (A).