Pneumatic Tire Inner Liner Bonding Offset
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Solution Overview
Problem
Current methods for molding pneumatic tires face challenges in achieving uniform thickness at joints, preventing air retention, and reducing peeling-off of the inner liner and carcass ply, which can lead to air leakage and tire damage.
Innovation Solution
A method involving bonding the inner liner and unvulcanized rubber sheet with end portions displaced in the width direction, cutting to a constant length, and winding on a drum with the inner liner on the inner surface side, using a composite layer of thermoplastic elastomer and polyamide-based polymers to enhance adhesion and reduce joint thickness differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inner liner film and unvulcanized inner liner rubber are bonded beforehand with aligned end edges and wound on the drum, then the manufacturing process is simple, but the joint thickness becomes large causing air retention and peeling-off
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the end edges of the inner liner film and unvulcanized rubber sheet during bonding. Instead of aligning the ends (symmetric approach), the film end is positioned offset from the rubber sheet end, creating an asymmetric joint configuration that prevents overlapping when wound on the drum, thereby eliminating thick joints and air retention issues
2Weight of moving object
If the inner liner is made thinner to reduce weight, then weight saving is achieved, but air permeation resistance decreases
Solution Approach 1:
The patent uses composite materials by combining the inner liner film (thermoplastic elastomer) with the unvulcanized rubber sheet to form a laminated structure. This composite construction allows the use of thinner film while maintaining air permeation resistance through the layered configuration, achieving weight reduction without sacrificing reliability
3Ease of manufacture
If the joint of the inner liner has weak adhesive strength, then material selection is easier, but peeling-off occurs during driving causing air leakage
Solution Approach 1:
The patent applies preliminary action by bonding the inner liner film to the unvulcanized rubber sheet before the winding and vulcanization process. This pre-bonding ensures strong adhesive strength is established in advance, preventing peeling-off during subsequent driving conditions. The offset end edge configuration further enhances this by eliminating weak overlapping joints
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in improved uniformity, reduced air retention, and enhanced adhesion between the inner liner and carcass ply, leading to better rolling resistance, static air pressure retention, and reduced flex crack growth.
Implementation Method 1
an inner liner which is a laminate of a first layer and a second layer, the first layer being a thermoplastic elastomer composition containing 0.1 to 50 parts by mass of an organic derivative of a clay mineral relative to 100 parts by mass of a thermoplastic elastomer mixture
Data Source
Figure 1~2
Figure 3~4(b)
Figure 5
AI summary
In a method for manufacturing a pneumatic tire, molding of a green tire has (a) an assembly step of bonding an inner liner (2) and an unvulcanized rubber sheet (3) with end portions thereof (2a, 2b; 3a, 3b) in a width direction being displaced from each other by 50 mm to 500 mm in the width direction to manufacture a laminate, (b) cutting the laminate to have a constant length corresponding to a width of a drum (5) to manufacture a cut sheet (4), and (c) a joining step of winding the cut sheet (4) on entire circumference of the drum (5) such that a cut surface thereof extends in a circumferential direction of the drum (5) and the inner liner (2) is disposed on an inner surface side, and joining the end portions (2a, 2b) of the inner liner (2) and joining the end portions (3a, 3b) of the unvulcanized rubber sheet (3) such that positions of the joined end portions are displaced by a constant distance.