Segmented Forming Drum for Tire Building
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Solution Overview
Problem
Existing forming drums struggle to efficiently support carcass structures during the building of tires with high differences between fitting diameter and rolling diameter, leading to inadequate support and potential defects such as wrinkles due to radial thrusts and non-continuous annular surfaces.
Innovation Solution
A forming drum design featuring radially mobile first and second sectors with kinematic mechanisms that allow for synchronous expansion and contraction, creating a substantially continuous annular surface in the expanded condition, while minimizing radial bulk in the contracted condition, thus providing effective support for tires with high diameter differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the forming drum uses a simple rigid structure, then the device complexity is low, but it cannot provide adequate support for tires with high diameter differences between fitting and rolling diameter
Solution Approach 1:
The forming drum is divided into multiple radially mobile sectors (first sectors and second sectors) that can independently move between contracted and expanded conditions. This segmentation allows the drum to adapt its radial dimensions to match different tire sizes while maintaining a relatively simple overall structure when collapsed.
Solution Approach 2:
The forming drum transitions from a static rigid structure to a dynamic configurable structure. The sectors are equipped with radial movement devices and kinematic mechanisms that enable synchronous expansion and contraction, allowing the drum to adapt its geometry to different tire diameters during the building process.
2Adaptability or versatility
If the forming drum expands radially to support high diameter differences, then the support capability improves, but the radial bulk increases
Solution Approach 1:
By segmenting the drum into multiple sectors with projections and cavities, the design allows compact nesting when collapsed. The projections of one sector fit into the cavities of adjacent sectors, minimizing the radial bulk when the drum is in the contracted condition while enabling full expansion when needed.
Solution Approach 2:
The sectors are designed with nested projections and cavities that allow them to pack efficiently when in the contracted condition. The projections of first sectors insert into the cavities of second sectors and vice versa, creating a compact nested arrangement that minimizes radial bulk while maintaining the ability to expand fully when required.
3Reliability
If the forming drum has non-continuous annular surface, then the device complexity is reduced, but wrinkles and defects occur during tire building
Solution Approach 1:
The annular surface is segmented into multiple sectors with projections and cavities. When in the expanded condition, the projections of one sector align with the cavities of adjacent sectors to form a substantially continuous annular surface, eliminating wrinkles and defects while maintaining a modular segmented structure.
Solution Approach 2:
The projections and cavities of adjacent sectors are designed to interlock and align, merging the individual sector surfaces into a substantially continuous annular surface when in the expanded condition. This merging eliminates gaps and discontinuities that would cause wrinkles, while each sector remains an independent manageable unit.
4Adaptability or versatility
If the forming drum uses fixed sectors, then the manufacturing precision is maintained, but the adaptability to different tire sizes is limited
Solution Approach 1:
The sectors are designed with radial movement devices and kinematic mechanisms that maintain geometric accuracy during movement. The kinematic mechanisms ensure synchronous expansion and contraction of all sectors, preserving the circular geometry and manufacturing precision while enabling adaptability to different tire sizes.
Solution Approach 2:
The kinematic mechanisms provide feedback control to ensure that all sectors expand and contract synchronously. This feedback maintains the circular geometry and geometric accuracy of the forming drum while allowing it to adapt to different tire diameters, preventing distortion or loss of precision.
Data Source
Figure 1
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AI summary
A forming drum (1) for building a tyre for vehicle wheels comprises a central shaft (2), first sectors (3) radially mobile between a contracted condition in which they are brought towards the central shaft (2) and an expanded condition in which they are radially moved away from the central shaft (2), second sectors (18) radially mobile between a contracted condition in which they are brought towards the central shaft (2) and an expanded condition in which they are radially moved away from the central shaft (2), radial movement devices (11) active between the central shaft (2) and the first sectors (3) to move the first sectors (3) between the contracted condition and the expanded condition and vice-versa. Kinematic mechanisms (27) are active between the first sectors (3) and the second sectors (18) and kinematically connect them to radially move the second sectors (18) between the contracted condition and the expanded condition and vice- versa when the first sectors (3) move radially between the contracted condition and the expanded condition and vice-versa. The first sectors (3) and the second sectors (18) are circumferentially aligned when they are in the respective expanded conditions to define a substantially continuous annular surface (la), the second sectors (18) are radially inner with respect to the first sectors (3) when the first sectors (3) and the second sectors (18) are in the respective contracted conditions.