Tire Building Drum Catenary Shaping Process
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Solution Overview
Problem
The manufacture of pneumatic tires often results in inherent residual stresses in the tire carcass, particularly in the apex, bead area, and sidewall, leading to tire non-uniformity, poor handling, and reduced rolling resistance due to compression forces and compound strain during the tire building process.
Innovation Solution
A method of building tires using a catenary shaping process on a tire building drum, where tire components are applied and shaped into a catenary structure with minimal strain, involving the application of beads, wedge components, and inflation under low pressure to maintain ply cords in tension, reducing residual stresses and preventing cord unraveling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional tire building methods are used with high compression forces and compound strain to transform components into toroidal shape, then the tire carcass can be formed, but inherent residual stresses are created in the apex, bead area and sidewall causing tire non-uniformity, poor handling and lower rolling resistance
Solution Approach 1:
The invention divides the tire building process into two distinct stages: a first stage drum for initial component assembly and a second stage drum for final shaping. This segmentation allows each stage to be optimized for its specific function, reducing the need for high compression forces in a single stage process and thereby minimizing residual stresses in the finished tire.
Solution Approach 2:
The first stage drum performs preliminary assembly of tire components into a cylindrical green carcass before the final shaping operation. By preparing the carcass structure in advance with proper component placement and initial forming, the second stage requires less aggressive compression and strain to achieve the final toroidal shape, thus reducing residual stresses.
2Shape
If high compression forces are applied to transform tire components into desired toroidal shape, then the tire carcass can be formed, but inherent residual stresses are created causing poor handling
Solution Approach 1:
The two-stage drum process segments the shaping operation, with the first stage creating a preliminary cylindrical form and the second stage completing the toroidal shape. This division allows gradual formation of the complex toroidal geometry without applying excessive compression forces in a single operation, thereby improving handling characteristics.
3Shape
If high compression forces and compound strain are applied to transform components into toroidal shape, then the tire carcass can be formed, but rolling resistance is reduced
Solution Approach 1:
The first stage drum performs preliminary formation of the cylindrical carcass with proper component alignment and initial tensioning. This preliminary action ensures that the second stage requires minimal compression to achieve the final toroidal shape, preserving the natural tension state of ply cords and reducing energy loss to rolling resistance.
Solution Approach 2:
The invention changes the physical parameters of the forming process by using low compression forces and maintaining ply cord tension throughout both stages. This parameter change from high-compression single-stage to low-compression two-stage forming reduces the compound strain applied to the carcass, thereby minimizing residual stresses and improving rolling resistance characteristics.
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 catenary method reduces residual stresses, improves tire uniformity, handling, and rolling resistance by maintaining ply cords in tension, preventing cord unraveling, and achieving a more efficient shaping process that minimizes material usage and distortion.
Implementation Method 1
inflating the carcass under a pressure of less than 400 mbar into engagement with a belt and tread package
Implementation Method 2
The carcass is inflated with airflow having a flow coefficient Cv of 5 to 10
Data Source
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AI summary
A method of building a tire carcass on a tire building drum (100) is disclosed. The method comprises the steps of: applying one or more tire building components (120, 130, 140, 150, 170, 180) onto a tire building drum (100) forming a cylindrically shaped tire carcass; placing a first and second bead (160) onto the tire carcass so that the lateral ends of the tire carcass extend axially outwardly of the respective bead (160); radially expanding a first and second bead lock mechanism (110, 112) into engagement with a respective first and second bead (160); inflating the carcass under a relatively low pressure into engagement with a belt and tread package (250) while moving the beads (160) axially inward; and continuing to move the beads (160) axially inwardly and then turning up the outer lateral ends of the cylindrically shaped tire carcass about the respective first and second bead (160).