Stepped Mating Surface Rigid Tire Core
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Solution Overview
Problem
Conventional rigid tire cores experience rubber intrusion and deterioration of roundness during vulcanization due to flat mating surfaces and thermal expansion, leading to uneven pressure and deformation.
Innovation Solution
The rigid core features stepped mating surfaces with a bordering surface region extending along the outer circumferential edge and a recessed surface region, allowing only the bordering surface to contact, which reduces flatness effects and absorbs thermal expansion deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If planar mating surfaces are used for core segments, then ease of manufacture is improved, but rubber intrusion occurs and roundness deteriorates during vulcanization
Solution Approach 1:
The mating surface is designed with non-uniform geometry featuring a recessed portion that creates a protruding contact region. This local variation in surface geometry concentrates contact pressure at specific locations (the protruding portions) rather than distributing it uniformly, which prevents rubber intrusion into gaps while maintaining manufacturability through simple recess formation.
Solution Approach 2:
The recessed portion introduces curvature variation to the otherwise planar mating surface. By creating a concave recess, the contact surface becomes curved rather than flat, which allows the protruding portions to make point or line contact with adjacent segments. This curved geometry better accommodates thermal expansion and maintains roundness during vulcanization.
2Device complexity
If planar mating surfaces are used for core segments, then device complexity is reduced, but gap formation occurs and rubber intrusion increases during vulcanization
Solution Approach 1:
Instead of making the entire mating surface complex, only a localized recessed portion is created. This simple local modification creates protruding contact regions that reliably prevent gap formation and rubber intrusion without significantly increasing overall device complexity. The recessed portion acts as a localized feature that solves the gap problem efficiently.
3Stress or pressure
If entire mating surfaces contact during vulcanization, then pressing force distribution is improved, but thermal expansion deformation causes uneven pressure and roundness deterioration
Solution Approach 1:
The contact pressure is concentrated at the protruding portions created by the recessed geometry. Rather than distributing pressure uniformly across the entire mating surface, the design creates localized high-pressure contact zones. This concentrated pressure distribution effectively prevents gap formation and rubber intrusion while the recessed geometry accommodates thermal expansion, maintaining roundness.
Solution Approach 2:
The curved surface created by the recessed portion allows for better adaptation to thermal expansion deformations. The curvature enables the contact surface to maintain pressure contact at the protruding regions even when the core segments expand unevenly due to temperature gradients during vulcanization, thereby preserving roundness.
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 configuration effectively suppresses rubber intrusion and maintains core roundness by improving surface matching and distributing thermal expansion stress, enhancing the core's durability and resistance to deformation.
Implementation Method 1
the core body (a) is subjected to a temperature rise from a normal temperature state during the formation of the green tire (approximately 15 to 50 degrees C.) to a high temperature state during the vulcanization molding (100 degrees C. or above)... a tread side is subject to a large amount of thermal expansion, and a bead side is subject to a small amount of thermal expansion
Data Source
AI summary
Provided is a rigid core for forming a tire, configured so that the intrusion of rubber into a gap between core segments is prevented and so that the lowering of roundness of a core body s prevented. The core body comprises a plurality of circumferentially divided core segments. Both circumferential end surfaces of each of the core segments are used as mating surfaces, and the mating surfaces adjacent to each other in the circumferential direction are abutted against each other to form the core body. At least one of the mating surfaces adjacent to each other in the circumferential direction is formed as a stepped mating surface comprising a bordering surface region extending along an outer circumferential edge of the mating surface, and a recessed surface region surrounded by the bordering surface region and recessed in a step shape from the bordering surface region so that only the bordering surface region contacts with the adjacent mating surface.