Tire Building Drum with Axially Moving Hubs
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Solution Overview
Problem
The existing tire building processes create inherent residual stresses in the tire carcass, particularly in the apex, bead area, and sidewall due to compression forces, leading to tire non-uniformity, poor handling, and reduced rolling resistance.
Innovation Solution
A second stage tire building drum with a central shaft and two hubs, where at least one hub is configured for unconstrained axial movement, featuring a bead receiving mechanism with curved pockets, allows for the formation of a catenary shape with minimal bead locking force, enabling the tire to be shaped with reduced cord tension and strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If compression forces and compound strain are applied to transform components into toroidal shape, then the desired tire shape is achieved, but inherent residual stresses are created in the apex, bead area and sidewall
Solution Approach 1:
The patent applies dynamics by making the hubs rotatable on the central shaft, allowing the tire to be shaped through rotational movement rather than static compression. The hubs can rotate independently to apply shaping forces dynamically, reducing residual stresses while achieving the desired toroidal shape.
Solution Approach 2:
The patent replaces the traditional mechanical compression system with an inflation-based system. Air is introduced into the tire carcass to inflate it into the belt and tread package, substituting mechanical compression with pneumatic pressure to achieve shaping, thereby reducing residual stresses.
2Stability of the object's composition
If bead locking force is applied to secure beads, then bead position is maintained, but cord tension and strain increase
Solution Approach 1:
The patent replaces mechanical bead locking force with pneumatic pressure. Air inflation provides the necessary force to secure beads in position without requiring mechanical clamping, thereby reducing cord tension and strain while maintaining bead stability.
Solution Approach 2:
The patent uses pneumatic pressure from air inflation to maintain bead position and secure the tire structure. This pneumatic system replaces mechanical bead locking mechanisms, reducing the forces applied to cord elements while achieving the same stabilizing effect.
3Shape
If high compression forces are applied during shaping, then tire shape is formed, but handling characteristics deteriorate
Solution Approach 1:
The patent replaces high compression forces with pneumatic inflation pressure to achieve shaping. This substitution allows the tire to be formed with more uniform stress distribution, improving handling characteristics while maintaining the desired tire shape.
Solution Approach 2:
The patent changes the physical parameter from mechanical compression force to pneumatic pressure. This parameter change allows for more controlled and uniform application of shaping forces, resulting in better tire uniformity and improved handling characteristics.
4Stability of the object's composition
If mechanical bead locking is used to secure beads, then bead position is fixed, but uniformity of strain distribution decreases
Solution Approach 1:
The patent replaces mechanical bead locking with pneumatic inflation, which applies pressure uniformly across the tire structure. This results in more uniform strain distribution while maintaining bead position stability, improving manufacturing precision.
Solution Approach 2:
The patent achieves homogeneity in strain distribution by using pneumatic pressure that acts uniformly throughout the tire carcass. This homogeneous pressure distribution replaces the non-uniform stress concentration caused by mechanical bead locking, improving strain uniformity.
Data Source
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AI summary
A second stage tire building drum is disclosed. The drum (100) comprises a first and second hub (120, 120'), wherein each hub is mounted on a central shaft (110) of the second stage tire building drum (100); wherein at least one of said hubs (120, 120') is configured for unconstrained axial movement on the central shaft (110); and wherein each hub (120, 120') has a bead receiving mechanism mounted on each hub. Also, a method of forming a tire on a tire building drum (100) from a green tire carcass (600) is disclosed. The method comprises the steps of (i) applying a green tire carcass (600) onto the tire building drum (100) by placing a first and second bead onto a first and second respective bead receiving member of the tire building drum, wherein no bead locking force is utilized or (ii) applying a green tire carcass (600) onto the tire building drum (100) by placing a first and second bead onto a first and second respective bead pocket (212) of the tire building drum (100), wherein preferably a relatively low bead locking force is utilized and wherein at least one of the first and second respective bead pockets (212) are configured for unconstrained sliding in the axial direction. The method further comprises the step of inflating the carcass (600) into engagement with a belt and tread package (650) while at least one of the beads is free to move axially inward.