Tire Bead Toe Guard Composition for Mounting Damage Resistance
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Solution Overview
Problem
Pneumatic tire bead components face challenges in withstanding mounting and demounting forces without additional weight and cost, as existing solutions like chafers increase tire weight and rolling resistance.
Innovation Solution
Incorporating a toe guard made from a cross-linkable rubber composition with natural and synthetic rubber, a methylene donor and acceptor reinforcing resin system, and a sulfur curing system, which provides enhanced robustness and protection without the need for additional components like chafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chafer is added to protect the bead area, then the robustness and protection of the tire in the bead area is improved, but the weight and cost of the tire increase
Solution Approach 1:
The toe guard is integrated into the bead portion structure, merging the protective function with the existing bead component rather than adding a separate chafer layer. This combines the bead core, rubber composition, and protective toe guard into a unified structure that provides protection without the additional weight of a separate chafer component.
Solution Approach 2:
The toe guard provides localized reinforcement specifically at the radially-innermost section of the bead portion where mounting and demounting forces are most severe. The rubber composition is strategically applied only where needed for protection, rather than uniformly throughout the entire bead area, optimizing protection while minimizing additional weight.
2Reliability
If a chafer is added to protect the bead area, then the robustness and protection of the tire in the bead area is improved, but the cost of the tire increases
Solution Approach 1:
The toe guard is manufactured as an integrated part of the bead portion using the same cross-linkable rubber composition, eliminating the need for separate manufacturing processes and assembly steps required for a separate chafer. This merging reduces manufacturing complexity and cost.
Solution Approach 2:
The cross-linkable rubber composition serves multiple functions: it provides structural support for the bead portion, enables vulcanization bonding to the carcass ply, and forms the protective toe guard. This multi-functionality eliminates the need for separate materials and components, reducing overall cost.
3Reliability
If additional rubber layers are added to protect the bead area, then the protection and robustness are improved, but the rolling resistance increases
Solution Approach 1:
The protective rubber composition is applied locally only at the radially-innermost section of the bead portion where mounting forces are most severe, rather than as a continuous layer throughout the bead area. This localized application provides necessary protection while minimizing the additional material that would increase rolling resistance.
Solution Approach 2:
The cross-linkable rubber composition is vulcanized to create a highly cross-linked, durable protective layer with optimized mechanical properties. The vulcanization process transforms the rubber from a soft, flexible state to a more rigid, protection-oriented state only where needed, providing robustness without the continuous additional mass that would increase rolling resistance.
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 improves the robustness of the toe guard, reducing the likelihood of damage during mounting and demounting operations while maintaining low strain modulus for normal operation, thus enhancing tire durability and fuel efficiency.
Implementation Method 1
a cross-linkable rubber composition... a sulfur curing system comprising sulfur and one or more accelerators
Implementation Method 2
a methylene donor and a methylene acceptor reinforcing resin system
Data Source
Figure 1
AI summary
A tire having a toe guard formed of a rubber composition having between 40 phr and 70 phr of natural rubber and between 30 phr and 60 phr of a synthetic rubber component. The synthetic rubber component may be selected from the group consisting of a polybutadiene rubber (BR), a styrene butadiene rubber (SBR), a polyisoprene rubber (IR) and combinations thereof but includes an amount of BR that is between 25 wt% and 100 wt% of the total weight of the synthetic rubber component. The rubber composition further includes a reinforcing filler, a methylene donor and a methylene acceptor reinforcing resin system and a sulfur curing system having a ratio by weight of the sulfur to one or more accelerators that is less than 1.