Tyre Bead Core Partial Vulcanization for Stability
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Solution Overview
Problem
The existing tyre bead structures, particularly those using bare metal wires, face challenges in maintaining geometrical stability and resistance to local deformations during manufacturing and use, leading to disalignments and reduced resistance to rupture, while also requiring flexibility for mounting and dismounting on wheel rims.
Innovation Solution
A process involving the application of a crosslinkable elastomeric material around metal wire coils, with partial vulcanization to achieve a specific sulfur content, ensuring geometrical stability, adhesion, and preventing overcuring, is implemented to enhance the structural strength and flexibility of the tyre bead structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rubberized wires are used for bead cores, then the bead core becomes rigid and compact after vulcanization, but flexibility is lost making mounting and dismounting difficult
Solution Approach 1:
The bead core is divided into two functional segments: an inner core made of bare wires that maintains rigidity and strength, and an outer covering made of crosslinkable elastomeric material that provides flexibility. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
The bead core uses a composite structure combining bare metal wires (for structural strength) with crosslinkable elastomeric material (for flexibility and adhesion). This composite approach resolves the contradiction by integrating materials with complementary properties.
2Ease of operation
If bare wires are used for bead cores, then flexibility for mounting and dismounting is improved, but geometrical stability and torsional strength are insufficient
Solution Approach 1:
The bead core is divided into two functional segments: an inner core made of bare wires that maintains rigidity and strength, and an outer covering made of crosslinkable elastomeric material that provides flexibility. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
The bead core uses a composite structure combining bare metal wires (for structural strength) with crosslinkable elastomeric material (for flexibility and adhesion). This composite approach resolves the contradiction by integrating materials with complementary properties.
3Strength
If full vulcanization is applied to the bead core, then structural strength is maximized, but reversion phenomena occur affecting road-holding
Solution Approach 1:
Instead of applying full vulcanization to the entire bead core, the invention applies partial vulcanization only to the elastomeric material covering. This partial action achieves sufficient adhesion and flexibility while avoiding the excessive crosslinking that causes reversion phenomena in the metal wire structure.
Solution Approach 2:
The vulcanization treatment is applied selectively to different parts of the bead core with different intensities. The elastomeric material receives full vulcanization for optimal adhesion, while the metal wire core receives no vulcanization to prevent reversion, creating local quality differences that resolve the contradiction.
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 improved geometrical stability and resistance to local deformations during manufacturing and use, while maintaining flexibility for easy mounting and dismounting, and preventing reversion phenomena that could affect road-holding.
Implementation Method 1
applying at least one layer of a crosslinkable elastomeric material around a plurality of coils of metal wires... subsequently subjected to a partial vulcanization in such a way that, after said partial vulcanization, said elastomeric material has an amount of free sulfur
Implementation Method 2
ensuring geometrical stability, adhesion, and preventing overcuring
Data Source
AI summary
Process for manufacturing a tyre, includes the following steps: (a) winding at least one metal wire so as to form a plurality of coils, the coils being radially superimposed and axially arranged side-by-side with respect to one another, so as to obtain a bead core; (b) applying at least one layer of a crosslinkable elastomeric material to the bead core obtained in step (a), so as to obtain a coated bead core; (c) partially crosslinking the at least one layer of crosslinkable elastomeric material, so as to obtain an amount of free sulfur of 30% by weight to 70% by weight, preferably of 40% by weight to 65% by weight, more preferably of 50% by weight to 60% by weight, with respect to the total weight of the sulfur present in the crosslinkable elastomeric material; and (d) applying a bead filler to the radial outer surface of the bead core obtained in step (c), so as to obtain a bead structure for a green tyre.