Multi-Compound Tire Tread Extrusion and Injection for Wet Grip

Solution Overview

Problem

Existing pneumatic tire tread compounds face a challenge in reconciling low rolling resistance with good wet grip performance, as compounds with low hysteresis loss are required for low rolling resistance but those with higher hysteresis loss are needed for good wet grip, making it difficult to achieve optimal dynamic responses simultaneously.

Innovation Solution

A process and plant are developed to manufacture a multicompound tread where blocks are composed of different portions with varying hysteresis losses, using a softer first compound for the main tread and a stiffer second compound for specific areas, allowing for a synergistic effect that improves wet grip without adversely affecting rolling resistance, with the process involving continuous extrusion and discontinuous injection, and a plant with an interconnection station for intermittent injection of the second compound into the preliminary tread band.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a single compound with low hysteresis loss is used for the tread, then rolling resistance is reduced, but wet grip performance deteriorates

Engineering Contradiction:

Improverolling resistanceVSAvoidwet grip performance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The tread is divided into multiple blocks, where each block can be composed of different rubber compounds with different hysteresis characteristics. This allows the tread to have low rolling resistance in some areas and good wet grip in others, resolving the contradiction between these two performance requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the tread are assigned different compound properties: some blocks use compounds optimized for low rolling resistance while others use compounds optimized for wet grip. This local differentiation allows each area to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #3Local quality

2Reliability

If a single compound with high hysteresis loss is used for the tread, then wet grip performance is improved, but rolling resistance increases

Engineering Contradiction:

Improvewet grip performanceVSAvoidrolling resistance

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The tread is divided into multiple blocks, where each block can be composed of different rubber compounds with different hysteresis characteristics. This allows the tread to have low rolling resistance in some areas and good wet grip in others, resolving the contradiction between these two performance requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the tread are assigned different compound properties: some blocks use compounds optimized for low rolling resistance while others use compounds optimized for wet grip. This local differentiation allows each area to perform its specific function optimally without compromising the other.

Inventive Principle:

Principle #3Local quality

3Productivity

If continuous extrusion and discontinuous injection are used in the manufacturing process, then productivity is improved, but process complexity increases

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The preliminary tread band is continuously extruded first, and then the second compound is injected into specific blocks during subsequent processing. This preliminary action allows the base structure to be created efficiently while enabling later customization of specific blocks without reworking the entire tread.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The manufacturing process is segmented into continuous extrusion of the base tread band and discontinuous injection of the second compound into specific blocks. This segmentation allows each stage to be optimized independently, maintaining high productivity while managing complexity.

Inventive Principle:

Principle #1Segmentation

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

This approach results in a tread with significant improvements in wet grip performance while maintaining favorable rolling resistance, suitable for winter/all-season applications, by strategically incorporating stiffer compound elements as studs on icy and snowy roads.

Implementation Method 1

an extrusion station (2), having a hopper (6) into which a first rubber compound is loaded, and an extruder (7) capable of producing, with the first rubber compound, a preliminary tread band (8)

Methodology Applied

Scientific EffectExtrusion: Extrusion

Implementation Method 2

an injection station (4) capable of introducing, into blocks of the preliminary tread band (8), the second rubber compound

Methodology Applied

Scientific EffectInjection molding:

Data Source

PatentEP4051493B1Procedure for producing a multi-compound tread for road vehicle tyres

Publication Date: 2023.10.18 BRIDGESTONE EURO NV SA

AI summary

A process for the manufacture of a tread band, wherein the blocks thereof comprise different portions having differing hysteresis losses. The process comprises a step for the extrusion of a preliminary tread band consisting of a first rubber compound and an injection step, wherein the preliminary tread band, once extruded, is subjected to the action of at least one injector arranged such as to penetrate into the layer of the preliminary tread band and to release a second rubber compound, which is distributed within the layer consisting of said first compound, maintaining exposed a surface that is suitable for defining a portion of the ground-contacting surface of the resulting tread band.