Coextruded Tire Tread Interface for Grip and Rolling Resistance
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Solution Overview
Problem
Existing tire treads face a challenge in achieving a balance between grip and rolling resistance, with current coextrusion processes not fully optimizing the performance of tread pattern blocks and reinforcing wedges.
Innovation Solution
A coextrusion process that incorporates a decoupling interface between tread pattern blocks and reinforcing wedges, using separate elastomer compounds with varying stiffness properties, allowing independent operation and reducing lateral deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single elastomer compound is used for both tread pattern blocks and reinforcing wedges, then the manufacturing process is simpler, but the performance compromise between grip and rolling resistance cannot be optimized
Solution Approach 1:
The tread is segmented into distinct functional zones: tread pattern blocks made from a first elastomer compound optimized for grip, and reinforcing wedges made from a second elastomer compound optimized for structural support and rolling resistance. This segmentation allows each component to be independently optimized for its specific function without compromising the other.
Solution Approach 2:
Different elastomer compounds with specific local properties are assigned to different regions of the tread. The tread pattern blocks use a compound with higher hysteresis for better grip, while the reinforcing wedges use a compound with lower hysteresis for reduced rolling resistance. Each region's material properties are locally optimized for its intended function.
2Strength
If tread pattern blocks and reinforcing wedges are joined directly, then structural integrity is maximized, but lateral deformation and instability occur during drift deformation
Solution Approach 1:
A third elastomer compound serving as an intermediary or decoupling layer is introduced between the tread pattern blocks and reinforcing wedges. This intermediate layer allows controlled relative movement and deformation between the stiffer wedges and softer tread blocks during lateral drift, preventing stress concentration and instability while maintaining overall structural integrity.
Solution Approach 2:
The mechanical properties of the interface between tread pattern blocks and reinforcing wedges are modified by introducing the third elastomer compound with intermediate stiffness characteristics. This changes the deformation parameters and stress distribution at the interface, allowing the system to accommodate lateral deformations without losing stability.
3Force
If reinforcing wedges are made stiffer to support tread pattern blocks during drift deformation, then lateral support is improved, but rolling resistance increases
Solution Approach 1:
The reinforcing function is segmented and assigned specifically to the wedges made from the second elastomer compound, while the tread pattern blocks made from the first compound focus on grip. This functional segmentation allows the wedges to be optimized for lateral support without requiring the entire tread structure to be stiff, thereby reducing overall rolling resistance.
Solution Approach 2:
The second elastomer compound used for reinforcing wedges has specifically tailored local mechanical properties - stiffer than the tread pattern block material but with controlled hysteresis characteristics. This local optimization provides necessary lateral support at the wedge locations while minimizing energy loss during rolling.
4Force
If tread pattern blocks are made softer to improve grip, then roadholding is enhanced, but lateral stability during drift deformation deteriorates
Solution Approach 1:
The third elastomer compound acts as a mediator that transfers and distributes lateral forces between the soft tread pattern blocks and the stiffer reinforcing wedges. This intermediate layer prevents direct stress transmission that would cause instability in the softer tread blocks during drift, while still allowing them to maintain their grip-optimizing softness.
Solution Approach 2:
The tread employs a composite structure with three different elastomer compounds, each contributing specific properties: the first compound provides grip through optimized tread block softness, the second compound provides structural stability through stiffer wedge material, and the third compound mediates between them. This composite approach allows the system to exhibit both softness for grip and stiffness for stability simultaneously.
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 decoupling interface enhances lateral grip and reduces rolling resistance by allowing each structure to operate independently, improving tire performance without degrading the other's functionality.
Implementation Method 1
a profiled element is formed by jointly extruding, in a common direction of flow, a plurality of elastomer compounds through a gap which is delimited on the one hand by an extrusion head and on the other hand by a receiving surface
Implementation Method 2
said third elastomer compound is placed between, and forms a joint with, the first elastomer compound emerging from the shaping channel and the second elastomer compound emerging from the flow channel, by covering the lateral wall of the wedge so as to form an interface layer called the 'decoupling interface' which isolates said lateral wall of the wedge from the tread pattern block while enabling said tread pattern block to come to bear laterally against said lateral wall of the wedge indirectly via said decoupling interface
Data Source
AI summary
The present disclosure relates to a coextrusion process for manufacturing a profiled element intended to form a tread for a pneumatic tire. The process includes coextruding a first elastomer compound forming an underlayer and reinforcing wedges, a second elastomer compound forming tread pattern blocks supported laterally by the wedges, and a third elastomer compound. The third elastomer compound is different from the first and second elastomer compounds and is interposed between the lateral wall of each wedge and the corresponding tread pattern block so as to form a decoupling interface for separating the mechanical behavior of the wedge from that of the tread pattern block.