Metallic Tire Reinforcing Cord With Elastomer-Penetrating Twist

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing metallic reinforcing cords for vehicle wheels lack adequate adhesion to elastomeric materials and do not allow sufficient penetration of elastomeric material between wires, leading to potential corrosion and fretting issues, while textile and hybrid cords require adhesive coatings for adhesion and do not provide adequate rigidity.

Innovation Solution

Developed metallic reinforcing cords with a part load elongation greater than or equal to 1% by twisting metallic wires with a predetermined twisting pitch, allowing elastomeric material to penetrate and adhere without the need for coatings, achieving a 'double modulus' mechanical behavior similar to hybrid cords.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If metallic wires are twisted together with small spacing, then rigidity and strength are improved, but adhesion to elastomeric material deteriorates due to insufficient penetration space

Engineering Contradiction:
ImproverigidityVSAvoidadhesion
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The metallic reinforcing cord is segmented into multiple individual metallic wires twisted together, creating discrete spaces between each wire. This segmentation allows elastomeric material to penetrate between the wires, establishing adhesion while maintaining the overall rigidity of the cord structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different local qualities by creating zones of varying wire spacing within the cord. The twisting geometry creates local regions where wires are closer together (providing rigidity) and regions where gaps exist (allowing elastomeric penetration and adhesion).

Inventive Principle:
Principle #3Local quality

2Reliability

If metallic wires are twisted with large spacing, then adhesion and elastomeric penetration are improved, but rigidity and strength deteriorate

Engineering Contradiction:
ImproveadhesionVSAvoidrigidity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The twisting geometry creates a dynamic balance where the cord exhibits different mechanical properties at different scales. At the macro level, the twisted structure provides rigidity; at the micro level between wires, the spacing allows elastomeric penetration. The part load elongation capability dynamically adjusts to accommodate both requirements.

Inventive Principle:
Principle #15Dynamics

3Reliability

If adhesive coatings are applied to textile or hybrid cords, then adhesion is improved, but device complexity and manufacturing steps increase

Engineering Contradiction:
ImproveadhesionVSAvoidcoating process
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the adhesion function from a separate coating layer and integrates it directly into the metallic cord structure itself. The metallic wires' inherent surface properties and geometric configuration provide adhesion through elastomeric penetration, eliminating the need for additional adhesive coatings or complex surface treatment processes.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The metallic reinforcing cord structure is self-sufficient for adhesion. The twisting geometry and surface characteristics of the metallic wires inherently provide the adhesion mechanism through elastomeric material penetration, without requiring external adhesive agents or additional processing steps.

Inventive Principle:
Principle #25Self-service

4Ease of manufacture

If metallic wires are used without elastomeric penetration, then manufacturing simplicity is maintained, but corrosion and fretting resistance deteriorate

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcorrosion resistance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The elastomeric material serves a protective function by penetrating and coating the metallic wires. This self-protecting mechanism is integrated into the cord structure, where the elastomeric matrix naturally fills the spaces between wires during manufacturing, providing corrosion and fretting protection without requiring separate protective coating processes.

Inventive Principle:
Principle #25Self-service

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 provides enhanced adhesion, rigidity, and fatigue resistance, with improved thermodynamic homogeneity and reduced risk of corrosion, suitable for various tire components.

Implementation Method 1

a metallic reinforcing cord having a part load elongation greater than or equal to 1%... by twisting together a plurality of metallic wires with a predetermined twisting pitch

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4077797B1Metallic reinforcing cord for tyres for vehicle wheels
Publication Date: 2025.10.08 PIRELLI TYRE SPA
  • EP4077797B1 patent drawingFigure 1
  • EP4077797B1 patent drawingFigure 2
  • EP4077797B1 patent drawingFigure 3~3a

AI summary

The invention relates to a metallic reinforcing cord (10) for tyres for vehicle wheels, comprising: - a) a plurality of metallic wires (11) twisted to one another with a single twisting pitch (P), or - b) a single metallic wire twisted with at least one second metallic wire with a single twisting pitch, or - c) a plurality of first metallic wires twisted to one another with a first twisting pitch to define a first strand of metallic wires and at least one second metallic wire twisted with said first strand of metallic wires with a second twisting pitch equal to or different from the first twisting pitch. The metallic reinforcing cord (10) has a part load elongation greater than or equal to 1%.