Tire Bead Reinforcement Layout to Suppress Layer Separation
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Solution Overview
Problem
Heavy-duty pneumatic tires face durability issues due to separation of organic fiber reinforced layers at the bead portions, particularly caused by improper rubber flow and stress concentration during the molding process, leading to cracking and reduced lifespan.
Innovation Solution
Incorporating a crack suppression layer with a higher 100% modulus than the sidewall rubber layer, positioned between the organic fiber reinforced layer and the sidewall rubber layer, and an inner rubber reinforcing layer adjacent to the carcass layer, which mitigates stress concentration and improper rubber flow, ensuring the organic fiber reinforced layer is sandwiched between these layers to prevent separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an organic fiber reinforced layer is embedded in the bead portion to improve durability, then the durability of bead portions is improved, but separation of the organic fiber reinforced layer at the end portion occurs due to stress concentration and improper rubber flow
Solution Approach 1:
A crack suppression layer is introduced as an intermediary between the organic fiber reinforced layer and the sidewall rubber layer. This intermediate layer suppresses cracking and prevents separation by distributing stress and controlling rubber flow during vulcanization, thereby resolving the contradiction between improving durability and preventing structural separation.
Solution Approach 2:
The 100% modulus of the crack suppression layer is specifically controlled to be at least 1.5 times that of the sidewall rubber layer. By changing the mechanical parameter (modulus) of the intermediate layer, the patent optimizes stress distribution and rubber flow characteristics to prevent separation while maintaining durability enhancement.
2Ease of manufacture
If the organic fiber reinforced layer is mechanically turned up with the carcass layer during molding, then the manufacturing process is simplified, but the cord inclination angle increases at the end portion causing separation
Solution Approach 1:
The crack suppression layer acts as a mediator between the organic fiber reinforced layer and the mold, controlling rubber flow during the mechanical turning-up process. This prevents excessive cord inclination angle formation at the end portion while maintaining the simplicity of the mechanical turning-up molding method.
Solution Approach 2:
By controlling the modulus parameter of the crack suppression layer to be at least 1.5 times that of the sidewall rubber layer, the patent optimizes the rubber flow characteristics during molding, preventing sharp increases in cord inclination angle while maintaining manufacturing simplicity.
3Productivity
If rubber flows improperly during vulcanization, then the molding process is faster, but rubber banks form and cause cracking during initial traveling stage
Solution Approach 1:
The crack suppression layer serves as an intermediary that controls and regulates rubber flow during vulcanization. It prevents improper rubber flow and rubber bank formation while maintaining efficient vulcanization speed, thereby preventing cracking during the initial traveling stage.
Solution Approach 2:
The specific modulus parameter of the crack suppression layer (at least 1.5 times that of sidewall rubber layer) is optimized to control rubber flow characteristics during vulcanization, preventing rubber bank formation and cracking while maintaining productive vulcanization speed.
Data Source
AI summary
In a pneumatic tire, a bead filler is radially outward of a bead core, a carcass turned up end is radially inward of an outer side end of the bead filler, the turned up end is spaced from a carcass body, a reinforcement layer is laterally outward of the bead filler, a sidewall rubber extends from a sidewall to the bead, an inner rubber reinforcing layer is between the bead filler and the reinforcement layer and adjacent to the turned up end, a crack suppression layer is between the reinforcement layer and the sidewall rubber, the crack suppression layer extends 5 mm or more from where the crack suppression layer overlaps, the reinforcement layer contacts the carcass body radially outwardly of the bead filler, and a 100% modulus KcM100 of the crack suppression layer is at least 1.5 times that of the sidewall rubber.