Zigzag Tire Sipe Structure for Ice Grip and Load Durability
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Solution Overview
Problem
Winter tires with numerous sipes face issues of reduced loading durability due to sipe bottom distortion under load and poor mold releasability during vulcanization molding.
Innovation Solution
The tire design incorporates zigzag sipes with tie bars that divide the sipe into wide portions, featuring varying groove widths and curvatures to enhance rigidity and prevent collapse, while ensuring mold release by maintaining sipe integrity during vulcanization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of sipes are provided in land portions to improve on-ice performance, then on-ice performance is improved, but the sipe bottom is likely to be distorted by load causing reduced loading durability
Solution Approach 1:
The sipe is segmented into multiple sections by dividing it into a first sipe portion, second sipe portion, and third sipe portion along its length. Each portion can independently deform under load, preventing concentrated stress at the sipe bottom and improving loading durability while maintaining the large number of sipes for on-ice performance
Solution Approach 2:
Different portions of the sipe are given different structural characteristics. The first, second, and third portions have varying widths and depths, creating local variations in flexibility and strength. This allows each portion to optimally respond to local stress conditions while collectively maintaining overall sipe functionality for ice grip
2Reliability
If a large number of sipes are provided in land portions to improve on-ice performance, then on-ice performance is improved, but cracks starting from the sipe bottom are likely to occur reducing durability
Solution Approach 1:
Dividing the sipe into multiple portions prevents crack propagation across the entire sipe length. If a crack initiates in one portion, the segmentation limits its spread, thereby extending sipe durability while maintaining the numerous sipes needed for on-ice performance
Solution Approach 2:
The varied widths and depths of different sipe portions create inherent stress distribution patterns that cushion against crack initiation. The structural variations act as pre-designed stress relief zones, preventing concentration of forces that would otherwise lead to crack formation
3Reliability
If numerous sipes are provided to improve on-ice performance, then on-ice performance is improved, but mold releasability during vulcanization molding deteriorates
Solution Approach 1:
The segmented sipe structure with varying widths creates natural release planes during vulcanization molding. The narrower portions allow mold release while the overall sipe configuration maintains ice performance, resolving the contradiction between numerous sipes and mold releasability
Data Source
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AI summary
A tire comprises a tread portion 2 provided with a first block 13 provided with a first sipe 15 which extends zigzag in a cross section orthogonal to the sipe length direction, and extends zigzag in a cross section parallel to the ground contacting top surface of the first block 13. The first sipe 15 is divided into a first portion 16 and a second portion 17 by a tie bar 18. The sipe bottom 16d in the first portion 16 communicates with a first wide portion 21. The sipe bottom 17d in the second portion 17 communicates with a second wide portion 22. The first wide portion 21 comprises an outer portion 31 and an inner portion 32. The outer portion 31 is formed by a pair of first arcuate groove wall portions 31a. The inner portion 32 is formed by a pair of second arcuate groove wall portions 32a. The first wide portion 21 and the second wide portion 22 do not communicate with each other.