Toroidal Forming Drum with Radially Movable Sectors for Tyre Bead Stability
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Solution Overview
Problem
The existing systems for building tyres face challenges in maintaining stable positioning of beads during the shaping process, leading to instability and difficulties in applying further components, especially in radially inner and axially outer zones due to the geometry of the expandable forming drum.
Innovation Solution
A process and plant that utilize a toroidal forming drum with radially movable sectors to provide a stable support for the beads, allowing for precise deposition of tyre components by ensuring axial abutment of bead cores against the drum's circumferential axially outer portions, which stabilizes the carcass structure and opposes thrust actions during coiling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an expandable forming drum with radially movable sectors is used to shape the carcass sleeve, then the drum can be compacted radially to allow easy insertion and removal, but this creates empty portions in the abutment surface that cause instability of beads and difficulties in applying components
Solution Approach 1:
The forming drum is divided into circumferentially consecutive sectors that can move radially independently. Each sector includes solid portions that contact the carcass sleeve and empty portions that facilitate drum compaction. This segmentation allows the drum to maintain stability during operation while enabling easy insertion and removal through radial compaction.
Solution Approach 2:
The forming drum transitions between a radially expanded state during tyre building (providing stable support) and a radially contracted state for insertion and removal. The sectors move radially between these states, dynamically adapting the drum's configuration to different operational phases to resolve the contradiction between stability and ease of operation.
2Manufacturing precision
If the forming drum is radially expanded to provide stable support for the carcass sleeve, then precise deposition of components is enabled, but this prevents easy insertion and removal of the drum
Solution Approach 1:
The drum is segmented into multiple independent sectors that can move radially. This segmentation enables the complex radial movement function to be achieved through simpler individual sector mechanisms rather than a monolithic complex structure, reducing overall device complexity while maintaining manufacturing precision.
Solution Approach 2:
The forming drum serves multiple functions: it provides stable support for precise component deposition when expanded, and enables easy insertion and removal when contracted. The same radial movable sector mechanism accomplishes both functions, reducing the need for separate systems and lowering overall device complexity.
3Area of stationary object
If radially inner circumferential edges of the abutment surface have large diameter, then the drum provides sufficient support area, but this causes instability in radially inner and axially outer zones where empty portions are larger
Solution Approach 1:
The abutment surface is designed with varying properties across different zones. Solid portions are strategically positioned to provide concentrated support in radially inner and axially outer zones where stability is most needed, rather than uniform distribution. This local quality optimization ensures adequate support area while maintaining stability in critical regions despite the presence of empty portions.
Data Source
AI summary
In a shaping station (13), a toroidal forming drum (23) is positioned within a carcass sleeve (12) comprising at least one carcass ply (3) associated with a pair of beads (6) in radially inner position. The carcass sleeve (12) is toroidally shaped by radial expansion of the forming drum (23). The forming drum (23) carrying the shaped carcass sleeve (12) is removed from the shaping station (13). Tyre components (7, 8, 9) are applied externally on the shaped carcass sleeve (12), carried by the forming drum (23). At the end of the shaping and during the application of the tyre components (7, 8, 9), axially inner sides of said beads (6) are arranged axially against respective circumferential axially outer portions (S1) of an abutment surface (S) carried by the expanded forming drum (23), having shape corresponding to an inner shape of the shaped carcass sleeve (12).