Tyre Curing Mold Bead Shaping with Inflatable Bladder
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Solution Overview
Problem
Existing methods for moulding and curing tyres, particularly for high-performance tyres, result in geometrical deformations and imperfections at the annular fixing structures due to inadequate shaping and uniformity, leading to defects and rejection, as they fail to ensure precise and uniform bead formation and sufficient 'bead force', causing rolling irregularities and vibrations.
Innovation Solution
A method involving a curing mould with an inflatable bladder and opposing surfaces that apply sequential squeezing pressures to shape the annular fixing structure, ensuring uniformity and high bead force by confining the bead area between the surfaces, allowing precise geometry and material distribution for optimal moulding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional moulding methods are used with simple mould cavities, then the manufacturing process is simple and fast, but the annular fixing structures suffer from geometrical deformations and lack uniformity
Solution Approach 1:
The moulding equipment is divided into multiple functional components: a curing mould with moulding cavity, opposing surfaces that can be moved independently, and an inflatable bladder positioned within the cavity. This segmentation allows each component to perform a specific function - the opposing surfaces provide mechanical confinement while the bladder provides uniform radial pressure, together achieving precise bead formation without requiring the entire mould system to be overly complex
Solution Approach 2:
An inflatable bladder is introduced as an intermediary element between the opposing surfaces and the green tyre bead. The bladder receives pressure from the opposing surfaces and translates it into uniform radial pressure on the bead, mediating the force transmission to achieve uniform annular fixing structures while protecting the direct contact between rigid surfaces and the flexible tyre material
2Productivity
If high pressure is applied to shape the bead quickly, then the moulding speed increases, but the bead area becomes non-uniform and defects occur
Solution Approach 1:
The opposing surfaces are moved toward each other first to establish the correct positioning and initial confinement of the bead area before the curing process begins. This preliminary mechanical confinement ensures the bead is properly shaped and positioned, creating a stable foundation that prevents defects during the subsequent curing when the bladder is inflated
Solution Approach 2:
The moulding process uses periodic action by first moving the opposing surfaces toward each other to establish bead confinement, then inflating the bladder to apply uniform radial pressure, and finally maintaining the pressure during curing. This staged, periodic application of force ensures uniform bead formation while maintaining productivity
3Ease of manufacture
If the bead area is left unconstrained during curing, then the moulding process is simpler, but the annular fixing structures develop geometrical irregularities and lose bead force
Solution Approach 1:
The opposing surfaces are designed to act locally on the bead area, providing confinement and shaping force specifically where needed at the annular fixing structures. This localized action ensures high bead force and uniform geometry at the critical bead regions without requiring the entire mould system to be overly complex or restrictive
Solution Approach 2:
The opposing surfaces are positioned and moved toward each other beforehand to establish the correct confinement of the bead area before curing begins. This preliminary action ensures the bead is properly shaped and positioned, creating the necessary mechanical support to maintain bead force and prevent geometrical irregularities during the curing process
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 ensures uniform annular fixing structures, reducing tyre defects, improving rolling regularity, minimizing vibrations, and enhancing handling performance by maintaining the bead area's confinement and resistance during moulding.
Implementation Method 1
an inflatable bladder positioned inside said curing mould and capable of exerting a pressure against said at least one of said first and said second surface so as to bring said first surface and said second surface closer together in such a way that said radially inner and axially inner surface portion and said radially inner and axially outer surface portion of said annular fixing structure are shaped
Data Source
AI summary
Equipment for molding and curing a green tire includes a curing mold including a first bead molding ring including a first surface for contacting a radially inner and axially inner surface portion of an annular fixing structure of the green tyre and a first sidewall plate including a second surface for contacting a radially inner and axially outer surface portion of the annular fixing structure. The first bead molding ring is radially extendable from a contracted operating position to an expanded operating position so as to delimit a portion of the annular fixing structure between the first sidewall plate and the first bead molding ring, and the first bead molding ring is translatable towards the first sidewall plate for generating a first squeezing pressure on the annular fixing structure. The equipment further includes an inflatable bladder associated for operation with the curing mold.