Wave Sipe Tread Structure for Tire Block Rigidity and Mold Release
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Solution Overview
Problem
Pneumatic tires with sipes face challenges in maintaining rigidity against collapse-deformation and shear deformation, leading to increased wear and reduced steering stability on dry surfaces, while existing wave-like sipe designs complicate mold release during vulcanization molding.
Innovation Solution
The tire features asymmetric tread patterns with sipes that undulate like waves, providing constant ridge heights and varying recess depths along the sipe depth direction, enhancing rigidity against collapse-deformation and improving mold release by allowing easier removal of sipe blades during manufacturing.
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 the rigidity of the blocks is reduced leading to collapse or shear deformation
Solution Approach 1:
The patent applies local quality by providing recesses and protrusions only at specific locations (both end portions) of the sipes rather than uniformly across the entire sipe structure. This localized modification allows the sipe wall surfaces to engage and bear each other where needed, maintaining block rigidity against collapse and shear deformation while preserving the braking performance benefits of the sipes on wet and icy surfaces.
2Strength
If sipes are shaped like waves in sipe depth direction to suppress deformation of blocks, then rigidity of blocks is increased, but removal of sipe blades during vulcanization molding is hindered
Solution Approach 1:
The patent uses local quality by implementing wave-like recesses and protrusions only at the end portions of the sipes rather than along the entire sipe length. This localized wave structure provides sufficient rigidity to suppress block deformation while maintaining ease of mold releasing, as the sipe blades can still be removed without excessive resistance compared to fully wave-shaped sipes.
3Ease of manufacture
If amplitude of recesses and protrusions is reduced to improve mold releasing, then mold releasing is improved, but bearing capability against collapse deformation is insufficient
Solution Approach 1:
The patent resolves this contradiction by concentrating the recesses and protrusions with adequate amplitude at the end portions of the sipes, while reducing or eliminating them in the central portion. This localized concentration provides sufficient bearing capability against collapse deformation at the ends where the sipe wall surfaces need to engage, while the reduced amplitude in the center portion facilitates easier mold releasing.
Solution Approach 2:
The patent applies partial action by providing recesses and protrusions at only the end portions of the sipes rather than uniformly across the entire sipe. This partial implementation is sufficient to achieve the desired rigidity against collapse and shear deformation, while avoiding the excessive resistance to mold releasing that would result from full-wave sipe structures.
4Ease of manufacture
If few recesses and protrusions are formed along sipe depth direction, then mold releasing is easier, but rigidity against shear deformation is low
Solution Approach 1:
The patent applies local quality by concentrating recesses and protrusions at the end portions of the sipes where they are most effective for preventing shear deformation. This localized placement provides sufficient rigidity against shear deformation while minimizing the overall number of recesses and protrusions, thereby facilitating easier mold releasing during vulcanization molding.
Data Source
AI summary
Each sipe wall surface of a sipe in a tread portion of a pneumatic tire includes, along a sipe depth direction, multiple ridge portions and at least one valley portion bending like waves. Where viewed along the sipe depth direction, a recess depth of the valley portion with respect to the ridge portion on one wall surface varies depending on a position in the extension direction, the valley portion extends from a position at which the recess depth is maximized toward a position at which the recess depth is minimized, and the recess depth decreases as the valley portion extends from the side of the maximum-depth valley portion toward the maximum ridge portion. The sipe is provided in at least one of a first half-tread region on a first side or a second half-tread region on a second side in a tire width direction.