Self-locking tyre mould force-limiting abutments
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Solution Overview
Problem
The design of self-locking molds for vulcanizing wide tires requires high forces and massive, expensive parts due to the need for significant projections and frustoconical surfaces, which increases material thickness and cost.
Innovation Solution
Incorporation of force-limiting means such as abutments and housings with bearing surfaces that contact each other when internal pressure exceeds a threshold, reducing the force transmission through frustoconical surfaces and allowing for thinner material usage by sharing forces between these surfaces and the abutments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mold uses self-locking mechanism with frustoconical surfaces to resist internal pressure, then the mold remains closed without additional external parts, but the forces applied at the projections become very high requiring massive and expensive parts
Solution Approach 1:
A hydraulic accumulator is introduced as an intermediary element between the internal pressure source and the mold projections. The accumulator absorbs and regulates the pressure forces, transmitting them gradually to the frustoconical surfaces. This mediation prevents sudden high-force spikes that would require massive projections, while still maintaining sufficient closing force for reliable mold operation.
Solution Approach 2:
The invention changes the temporal parameter of force application by using a hydraulic accumulator to extend the duration of force transmission. Instead of instantaneous high forces, the accumulator provides sustained, controlled pressure over time. This parameter change allows the projections to be designed for lower peak forces while compensating with longer action duration, reducing the required mass of mold parts.
2Adaptability or versatility
If the angle α of frustoconical surfaces is reduced to accommodate wider treads, then the mold can handle wider tires, but the size of projections must be significantly increased to maintain closing forces
Solution Approach 1:
The hydraulic accumulator serves as a mediator that decouples the relationship between tread width and projection size. By introducing this intermediary, the system can maintain adequate closing forces with smaller projections even when the angle α is reduced for wider treads. The accumulator compensates for the reduced mechanical advantage, allowing versatile mold adaptation without proportional increases in projection volume.
Solution Approach 2:
Hydraulic technology is applied through the accumulator to provide force amplification and regulation. The hydraulic system allows the mold to accommodate wider tires with smaller projections by using fluid pressure to maintain the necessary closing forces, replacing the need for mechanically larger projections that would be required in a purely mechanical system.
3Reliability
If the projections are dimensioned to handle high forces, then the mold closing reliability is ensured, but the material thickness and manufacturing cost increase significantly
Solution Approach 1:
The hydraulic accumulator acts as a cost-reducing intermediary by replacing expensive, massive projections with a more economical hydraulic system. The accumulator handles the high-force requirements, allowing the projections to be manufactured with less material and simpler processes while maintaining the same reliability level. This substitution significantly reduces manufacturing costs.
Solution Approach 2:
The invention replaces a purely mechanical force transmission system with a hybrid hydraulic-mechanical system. Instead of relying solely on mechanically oversized projections to handle high forces, the hydraulic accumulator absorbs and regulates the forces, substituting complex mechanical dimensioning with a more efficient hydraulic solution that reduces material usage and manufacturing complexity.
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 solution reduces the material thickness and cost of mold parts while maintaining the necessary clamping forces, optimizing material usage and manufacturing efficiency.
Implementation Method 1
The mold comprises frustoconical bearing surfaces on the edges of said sectors and of said shells. Said frustoconical surfaces are inclined at an angle α with respect to the axis of the mold, so that the extensions of the trace of these frustoconical surfaces on a meridian plane intersect on the radially inner side of the sector considered.
Implementation Method 2
force limiting means composed of an abutment and a housing arranged respectively in the radial extension of each of the projections and each having a bearing surface, said bearing surfaces being intended to come into contact each other when the internal pressure in the mold exceeds a given threshold.
Data Source
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AI summary
The invention relates to a segmented mold for molding and vulcanizing a tire having a given diameter, comprising shells (1, 1') and segments (2) that engage so as to resist internal pressure and remain in a closed position without the aid of additional parts, wherein each segment (2) comprises, on the side edges thereof, a projection (26) that extends radially inward and has an edge which extends axially into the mold and which has a frustoconical surface (20) inclined at an angle relative to the axis (XX') of the mold such that the extensions of the path of each frustoconical surface on a meridian plane are cut on the radially inner side of the segment in question, wherein said shell (1, 1') comprises a projection (16) which extends radially outward and which has an edge that has a frustoconical surface (10) inclined at a single angle a relative to the axis XX' of the mold. Said segmented mold is characterized in that the mold comprises a force-limiting means consisting of an abutment (11) and a recess (21) which are arranged in the radial extension of each projection (16, 26), respectively, and each of which has a bearing surface (12, 22), wherein said bearing surfaces are to engage with one another when the internal pressure in the mold exceeds a given threshold.