Pneumatic Tire Sipe Wall Wave-Like Profile for Rigidity and Demolding
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Solution Overview
Problem
Pneumatic tires with sipes face degradation in rigidity and steering stability on dry roads due to flexed blocks, and demolding issues during vulcanization molding, as existing techniques fail to balance sipe rigidity and ease of mold removal effectively.
Innovation Solution
The tire features sipe wall surfaces with wave-like portions forming surface recesses and protrusions along the sipe depth direction, where the recess depth reduces gradually towards the center, allowing the sipe walls to support each other and improve demolding by reducing the likelihood of the sipe cutting edge coming off during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sipes are provided in blocks of tread portion to improve braking performance on wet and icy road surfaces, then braking performance is improved, but rigidity of the blocks is degraded
Solution Approach 1:
The sipe wall surfaces are designed with wave-like portions that create curved recesses and protrusions instead of straight configurations. This curvature allows the sipe walls to interlock and support each other when flexed, maintaining block rigidity while preserving the braking performance benefits of the sipes on wet and icy surfaces.
Solution Approach 2:
The wave-like portions are specifically positioned at the sipe wall surfaces rather than uniformly throughout the entire sipe structure. This localized modification provides structural support exactly where needed (at the walls) while maintaining the open sipe configuration necessary for water and ice chip evacuation, thus resolving the contradiction between braking performance and block rigidity.
2Strength
If sipes are formed in a wave shape to enhance block rigidity, then rigidity is improved, but demolding of the tire becomes difficult
Solution Approach 1:
The wave-like portions are positioned only at the sipe wall surfaces, leaving the central sipe opening relatively open and accessible. This localized application provides rigidity enhancement without creating excessive complexity in the sipe structure that would hinder mold removal, thus balancing block rigidity improvement with ease of demolding.
Solution Approach 2:
Instead of making the entire sipe structure wave-like (which would overly complicate demolding), the wave portions are applied partially only to the sipe walls. This partial application is sufficient to provide the needed rigidity support while avoiding excessive complexity that would prevent successful demolding of the tire.
3Ease of manufacture
If the width of recesses/protrusions of bent portions is reduced to improve demolding, then demolding is improved, but rigidity of blocks is not sufficiently improved
Solution Approach 1:
The wave-like portions are positioned specifically at the sipe wall surfaces where they can provide structural support for rigidity enhancement. By concentrating the wave structure at the walls rather than reducing recess/protrusion width throughout the entire sipe, the design achieves both improved demolding and sufficient block rigidity.
Data Source
AI summary
In a tread portion of a pneumatic tire, a first sipe wall surface of a sipe includes at least two first peak portions and at least one first valley portion at each position of the sipe extension direction, which are bent in a wave-like shape to form surface recesses and protrusions along a sipe depth direction. The first valley portion is sandwiched between the two first peak portions in the sipe depth direction, and extends from one end of the sipe in the extension direction to the other end of the sipe in the extension direction. A recess depth of the first valley portion with respect to the two first peak portions gradually reduces. A position of at least one of the two first peak portions in the sipe depth direction and a position of the first valley portion in the sipe depth direction become gradually closer.