Vulcanisation Mould Undulated Junction Line for Stress Distribution
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Solution Overview
Problem
The existing moulding and vulcanisation process for tyres, especially those designed for loose terrain, often results in surface and structural defects due to excessive stress during mould opening, which causes deformations and material removal issues, particularly at the radially inner ends of tread ribs.
Innovation Solution
A mould with an undulated profile junction line between its half-parts, where the crests intersect the axially inner terminal portions of the slots, allowing for a more even distribution of stresses and reducing concentration at the rib cusps, thereby facilitating easier tyre removal with reduced deformation and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a two half-parts mould is used for vulcanising tyres with complex tread designs, then the tyre can be properly formed and removed, but surface and structural defects occur on the ribs due to stress concentration during mould opening
Solution Approach 1:
The junction line between the two half-parts of the mould is designed with an undulated profile instead of a straight line. This curved configuration distributes the stress more evenly during mould opening, preventing stress concentration at specific points that would cause defects on the rib surfaces.
2Productivity
If the mould half-parts are forced apart to remove the tyre, then the tyre can be extracted, but excessive stress is transmitted to the ribs causing deformations and material removal
Solution Approach 1:
The undulated junction line configuration allows the mould half-parts to separate more gradually and evenly, reducing the peak stress transmitted to the tyre ribs during the extraction process.
3Device complexity
If the junction line between mould half-parts is a straight line, then the mould structure is simple, but stress concentrates at the axially inner terminal portions of slots causing rib defects
Solution Approach 1:
The undulated profile of the junction line introduces a curved geometry that naturally distributes stress away from concentrated points. While this increases mould complexity slightly, it dramatically improves rib surface quality by preventing stress concentration at the axially inner terminal portions of the slots.
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 significantly reduces defects in the tread design by evenly distributing stresses during mould opening, ensuring improved quality and reducing mechanical stress on the mould and vulcanisation press components.
Implementation Method 1
the administration of heat in order to determine the chemical cross-linking of the elastomeric material and the consequent structural stabilization of the moulded tyre
Implementation Method 2
the elastic deformability of the vulcanised tyre is exploited, such tyre still hot due to the vulcanisation, in order to allow the forced moving apart of the half-parts
Data Source
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AI summary
A mould comprising a first and a second half-part (15a, 15b) that are mutually side-by-side along a geometric centring axis (X) in order to define a moulding cavity (16). An internal wall (16a) of the moulding cavity (16) has a first and a second series of slots (17a, 17b) having the respective axially outer terminal portions (19a) respectively in the first and in the second half-part (15a, 15b). The slots (17a, 17b) respectively belonging to the first and second series are circumferentially offset from each other and have respective axially inner terminal portion (20a, 20b) in proximity to an intermediate reference plane (P). A junction line (22) between the first half- part (15a) and the second half-part (15b) has an undulating progression astride the intermediate reference plane (P), to form alternatively arranged crests (23), each intersecting the axially inner terminal portion (20a, 20b) of one of the slots (17a, 17b).