Pneumatic Tyre Core Flap Forming to Reduce Ply-Turn Air Pockets
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Solution Overview
Problem
The existing methods for producing pneumatic tires face issues with weak connections and deformations during the ply turning process, leading to reduced torsional rigidity, steering stability, and driving stability due to air pockets and incomplete bonding between the carcass fabric blank and the core flap.
Innovation Solution
A shaping step is introduced before the ply turning step, using fluid-actuated shaping devices to press the core lug onto the carcass fabric blank, ensuring a homogeneous distribution of forming force in the axial and radial directions, thereby improving the bonding and adaptation to the drum contour.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ply turning step is carried out by expanding a turn-over bladder after the second positioning step, then the turn-up section is guided around the tire core and core flap, but air pockets form between the carcass fabric blank and core flap, leading to weak bonding
Solution Approach 1:
The core flap is pre-shaped onto the drum contour using fluid-actuated bellows before the ply turning step. This preliminary action ensures that the bonding surface is already conforming to the drum contour, eliminating air pockets that would otherwise form during the subsequent ply turning operation, thereby ensuring reliable bonding between the carcass fabric blank and core flap.
Solution Approach 2:
The forming process is divided into two separate stages: first, the core flap is shaped onto the drum contour using fluid-actuated bellows; second, the ply turning is performed. This segmentation allows each step to be optimized independently, ensuring proper bonding conditions are established before the turn-up section is folded over.
2Reliability
If the core flap is pressed onto the carcass fabric blank during ply turning, then bonding is achieved, but the core flap deforms and loses its initial shape
Solution Approach 1:
The core flap is pre-shaped onto the drum contour using fluid-actuated bellows before the ply turning step. This preliminary shaping action establishes the correct geometry and bonding surface conformality, so that when bonding occurs during ply turning, the core flap maintains its intended shape without deformation.
Solution Approach 2:
Fluid pressure is used to control the shaping process, allowing precise control of the forming force applied to the core flap. This enables the core flap to be conformally shaped onto the drum contour while maintaining its structural integrity and intended geometry.
3Stability of the object's composition
If adhesives are used to protect the ply turn-up from deformation, then stability during processing is improved, but the bonding between carcass fabric blank and core flap is compromised due to air pockets
Solution Approach 1:
The core flap is pre-shaped onto the drum contour using fluid-actuated bellows before ply turning. This eliminates air pockets and ensures proper bonding conditions are established beforehand, making additional adhesive applications unnecessary and avoiding the trade-off between stability and bonding quality.
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
This method enhances the bonding between the core flap and carcass fabric blank, reduces air pockets, and ensures precise geometry, resulting in improved torsional rigidity and stability of the tire bead, enhancing driving and steering stability.
Implementation Method 1
a first pressurizable and expandable bellows which, during the shaping step, shapes the core lug onto the carcass fabric blank with a first portion of the shaping force as pressure in the axial direction of the carcass drum, and a second pressurizable and expandable bellows which, during the shaping step, shapes the core lug onto the carcass fabric blank with a second portion of the shaping force as pressure in the radial direction of the carcass drum
Data Source
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AI summary
The invention relates to a method for manufacturing a pneumatic tire with a tire carcass and at least one tire bead having a core flap (20). The method comprises a first positioning step, comprising positioning a carcass fabric blank (10) on a carcass drum (2) having a drum contour (8, 12, 14). Furthermore, the method comprises a second positioning step following the first positioning step, comprising positioning the core flap (20) on the carcass fabric blank (10). The method further comprises a layer-turning step following the second positioning step, comprising turning a layer section (16) of the carcass fabric blank (10) around the core flap (20).After the second positioning step and before the layer changeover step, a forming step is carried out in which the core flap (20) is pressed onto the carcass fabric blank (10) positioned on the carcass drum (2) by means of a forming force and is thereby formed against the drum contour (8, 12, 14). The invention further relates to a tire manufacturing machine (2, 4, 26) for carrying out the method.