Bias Tire Reinforcement Layer Prevents Ply Joint Cracks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Bias tires often experience joint cracks at the overlap of the innermost ply due to the trapping of mold release agents between the ends of the ply, which is exacerbated by the angle change of the cords during tire expansion.
Innovation Solution
A reinforcement layer made of multiple cords is applied to the innermost ply's circumferential edge, covering a significant portion of the tire's inner surface, to prevent the mold release agent from being trapped and to maintain the cord's angle separation from the tire equator, thereby avoiding joint cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mold release agent is applied to the innermost ply before vulcanization, then the green tire achieves good releasability from the vulcanization bladder, but the mold release agent becomes trapped between the ends of the innermost ply causing joint cracks
Solution Approach 1:
The patent introduces a specific cord arrangement as an intermediary structure between the mold release agent and the trapped space. The cords are arranged to incline toward each other at the joint, creating a geometric configuration that prevents the mold release agent from being trapped, while still allowing the green tire to be released from the vulcanization bladder.
Solution Approach 2:
The patent changes the geometric parameters of the cord arrangement at the joint area. Specifically, the cords are arranged to incline toward each other rather than running parallel, and this inclination angle is controlled to be within a specific range (0° to 45°). This parameter change prevents trap formation while maintaining releasability.
2Stability of the object's composition
If the cord angle of the ply is less than 90° relative to the tire equator, then the bias tire structure is maintained, but the cord angle changes during green tire expansion causing the mold release agent to be trapped between the ply ends
Solution Approach 1:
The patent controls the cord inclination angle parameter within a specific range (0° to 45°) to prevent excessive angle changes during expansion. By limiting the inclination angle, the relative positional change between cord ends during expansion is reduced, preventing mold release agent entrapment while maintaining the bias tire structure.
Solution Approach 2:
The patent applies a local quality approach by specifically arranging cords with controlled inclination angles at the joint area, while other parts of the ply can have different cord arrangements. This localized control of cord geometry at the critical joint region prevents trapping without affecting the overall bias tire structure.
Data Source
AI summary
Provided is a bias tire includes a carcass extending between a pair of bead portions, a pair of sidewall portions, a tread, and a reinforcement layer (5), formed by cords (5Cb), disposed so as to cover at least a portion of a tire circumferential edge (BEi) on the inner side, in the tire radial direction, of the innermost ply (2Bi) of the carcass in a tire half portion (HFa) on a side where, as a cord (Cb) of a tire circumferential end on the inner side, in the tire radial direction, of the innermost ply (2Bi) approaches the tire circumferential edge on the inner side, in the tire radial direction, of the innermost ply (2Bi) along the tire circumferential direction, the cord (Cb) is inclined so as to separate from the tire equator (CL).