Tire Building Drum Axial Hub Control for Residual Stress Reduction
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Solution Overview
Problem
The existing tire building processes create inherent residual stresses in the tire carcass due to high 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, each with a bead receiving mechanism featuring bead segments with pockets, allowing for controlled axial movement and low-pressure clamping, enabling the tire to be shaped into a catenary structure with minimal strain, using low-pressure, high-volume air inflation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high pressure, low volume shaping air is utilized to bring beads together rapidly, then shaping speed is improved, but residual stresses increase causing tire non-uniformity and poor handling
Solution Approach 1:
The patent employs dynamic control of bead position through movable hubs that can translate axially at controlled velocities. This allows the bead receiving mechanisms to adapt their position during the shaping process, enabling rapid shaping while maintaining uniform strain distribution and minimizing residual stresses through continuous adjustment rather than fixed high-pressure compression
Solution Approach 2:
The patent changes the parameter of bead clamping force from high pressure to low pressure, and controls the axial translation velocity of hubs to achieve shaping. By using low-pressure clamping forces and controlling the velocity of hub movement, the system achieves effective shaping without creating the high compression forces that lead to residual stresses and tire non-uniformity
2Shape
If high compression forces are applied to force components into toroidal shape, then shaping effectiveness is improved, but inherent residual stresses increase
Solution Approach 1:
Instead of applying external high compression forces to force the tire into shape, the patent allows the tire to assume its natural toroidal shape through low-pressure inflation and controlled hub movement. The bead receiving mechanisms guide the beads into proper position without high compression, and the tire components self-organize into the desired toroidal configuration, effectively inverting the conventional approach of forcing shape versus allowing natural shape formation
Solution Approach 2:
The patent uses low-pressure inflation pneumatic systems instead of high-pressure mechanical compression. By utilizing controlled low-pressure air inflation combined with axial hub movement, the system achieves effective shaping without the high compression forces that create residual stresses, demonstrating a pneumatic-based alternative to mechanical compression
3Productivity
If rapid bead convergence is achieved through high pressure shaping, then productivity is improved, but tire handling performance deteriorates
Solution Approach 1:
The movable hubs with controlled axial translation provide dynamic adjustment capability that maintains tire uniformity and handling performance while achieving rapid shaping. The system can quickly reposition bead receiving mechanisms to accelerate the shaping process without compromising the uniform strain distribution needed for good handling performance
Solution Approach 2:
By changing from high-pressure static compression to low-pressure dynamic control with controlled hub velocity, the system achieves both high productivity and good handling performance. The controlled velocity of hub movement allows rapid shaping while maintaining uniform strain distribution, effectively decoupling productivity improvement from handling performance degradation
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
The process reduces residual stresses, resulting in a tire with uniform strain distribution, improved handling, and enhanced rolling resistance by maintaining ply cords in tension and preventing cord unraveling.
Implementation Method 1
the inner sleeve has an inner surface that is threadedly engaged with an internal screw positioned within the inner sleeve for axial translation
Implementation Method 2
utilizing low pressure, high volume shaping air to inflate the green tire carcass into a catenary shaped green tire
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'). Each hub is mounted on a central shaft (110) of the second stage tire building drum (100) and each hub (120, 120') is mounted on an inner sleeve (139). The inner sleeve (139) has an inner surface that is threadedly engaged with an internal screw (114) positioned within the inner sleeve (139) for axial translation; or the inner sleeve (139) is freely axially slidable on the central shaft (110). Each hub (120, 120') has a bead receiving mechanism, wherein said bead receiving mechanism includes one or more bead segments (210), and wherein each bead segment has a pocket (212). Also, a method of forming a tire having a first and second bead on a tire building drum (100) is disclosed. The method comprising the steps of: applying a green tire carcass (610) onto the tire building drum (100), said tire building drum (100) having a left and right hub (120, 120'), said first or left hub (120) having a first bead pocket (212), and said second or right hub (120') having a second bead pocket (212); placing the first and second bead onto a first and second respective bead pocket (212) of the tire building drum (100); and inflating the carcass (610) into engagement with a belt and tread package (650) while (i) moving at least one of the left and right hubs (120, 120') in the axial direction at a controlled velocity towards the other respective hub or (ii) allowing at least one of the first and second bead pockets (212) to freely move in the axial direction.