Method for producing a pneumatic tyre
Patent Information
- Application Number
- EP2024705349
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-02-17
- Filing Date
- 2024-01-17
- Publication Date
- 2025-12-24
AI Technical Summary
Existing methods for producing pneumatic tires with high uniformity requirements, especially when using carcass plies with high stiffness, result in increased waste and complexity, leading to longer cycle times and reduced economic efficiency due to significant length differences between the inner layer and carcass ply at the bead cores.
A method involving an expandable tire building drum with radially movable core fixations that move to a larger radius to detach the inner layer and carcass ply from bellows, followed by expansion to form shoulders, ensuring minimal length differences and uniform tension between bead cores, facilitated by a computer program product and device.
This approach enables the reliable production of pneumatic tires with reduced cycle time and enhanced uniformity by minimizing length differences and achieving uniform mechanical tension between bead cores, thereby improving economic efficiency and reducing waste.
Smart Images
Figure DE2024035004_22082024_PF_FP
Abstract
Description
[0001] Description
[0002] Method for producing a pneumatic tire
[0003] The invention relates to a method for producing a pneumatic tire comprising an inner layer, a carcass ply, a bead core, a tire belt, and a tread. Furthermore, the invention relates to an apparatus for producing a pneumatic tire comprising an expandable tire building drum and dimensionally stable core fixations arranged axially to the tire building drum, and to a computer program product.
[0004] In the two-stage tire manufacturing process, after winding an inner layer and a carcass ply, a shoulder is formed during tire construction, for example, by expanding the carcass drum. A bead core is inserted before the ply turn-up.
[0005] For tire uniformity, it is important that the inner layer and the carcass ply exhibit small length differences and uniform mechanical stress across the circumference between the bead cores. Uniformity requirements for tires are increasing, with the length differences between the inner layer and the carcass ply increasing due to carcass plies with higher stiffness, even with consistent processes. Therefore, existing processes and devices with high tire uniformity requirements, especially when using carcass plies with high stiffness, result in increased rejects or are particularly complex, which increases cycle times and reduces the cost-effectiveness of the process.
[0006] Against this background, the invention is based on the object of designing a method and a device as well as a computer program product in such a way that pneumatic tires with an inner layer and a carcass ply can be produced in a process-reliable manner without or at least with only a slight increase in cycle time, which have particularly small length differences between the bead cores over the circumference in order to reliably meet high uniformity requirements for pneumatic tires.
[0007] This object is achieved by a method according to the features of patent claim 1 as well as a device and a
[0008] Computer program product according to the independent claims. The dependent claims relate to particularly useful developments of the invention.
[0009] According to the invention, a method for producing a pneumatic tire with an inner layer, a carcass ply, a bead core, a tire belt, and a tread is provided, comprising the following steps: a) Placing the inner layer and the carcass ply on a tire building drum and on a support ring with a bellows, b) Radially moving the core fixations to a larger radius, wherein the radius to which the core fixations are moved is larger than the unexpanded radius of the tire building drum, c) Radially moving the core fixations to a smaller radius, wherein the radius to which the core fixation is moved is not larger than the unexpanded radius of the tire building drum, d) Forming tire shoulders by expanding the tire building drum, e) Placing a bead core on the carcass ply at the drum shoulder, f) Fixing the bead core with the radially movable core fixation,g) Folding the carcass ply and the inner layer around the bead core by filling a bladder, h) Completion of the green tire with further steps.,
[0010] By radially moving the core fixations to a radius that is larger than the unexpanded radius of the tire building drum, the inner layer and the carcass ply are moved around the circumference in the area of the core fixations to a larger radius. This causes the inner layer and the carcass to detach from the bladders to which they were previously adhered, particularly by rolling. During subsequent expansion of the tire building drum, the non-contacting areas of the inner layer and the carcass, as well as the reduced adhesion of the inner layer and the carcass to the bladders in areas where the inner layer rests on the bladders, lead to smaller differences in the length of the inner layer and the carcass ply between the bead cores. Furthermore, a particularly uniform tension in the inner layer and the carcass ply between the bead cores is achieved.
[0011] A preferred embodiment provides that immediately after step a), the carcass ply is rolled onto the inner layer. Rolling the carcass ply onto the inner layer improves the adhesion between the carcass ply and the inner layer, thereby reducing relative movement between these layers and thus making it possible to produce a particularly uniform pneumatic tire.
[0012] A further preferred embodiment provides that, after step d), the rollers are moved to a smaller radius to apply the inner layer and the carcass ply to the drum shoulder. The movement of the rollers and the application of the inner layer and the carcass ply lead to a further equalization of the length of the inner layer and the carcass ply between the bead cores.
[0013] A further preferred embodiment provides that in step b), the core fixations are moved to a radius to create regions of the inner layer that do not rest on the bellows, wherein the radius is selected such that the region of the inner layer that does not rest on the bellows has an extension in the axial direction of the tire building drum that is no greater than the region of the inner layer that forms the tire shoulder. By forming a region of the inner layer that does not rest on the bellows and that is smaller than the region required to form the tire shoulder, bumps and irregularities of the inner layer are avoided in the formed tire shoulder.
[0014] A further preferred embodiment provides for steps c) and d) to be performed simultaneously. Simultaneous execution of steps c) and d) reduces the process time. Furthermore, the time the inner layer is in contact with the bellows after the relative movement has been performed and before the tire shoulder is formed, which can lead to increased adhesion, is minimized.
[0015] According to the invention, a device for producing a pneumatic tire is provided with an expandable tire building drum and dimensionally stable core fixations arranged axially to the tire building drum, wherein the device is designed to carry out the method according to the invention.
[0016] Such a device makes it possible to carry out the method according to the invention and thus to produce pneumatic tires with an inner layer and a carcass ply which have particularly small length differences between the bead cores over the circumference.
[0017] According to the invention, a computer program product is provided for operating a device for producing a pneumatic tire, comprising instructions which, when the program is executed by at least one processor unit, cause the processor unit to carry out the method according to the invention.
[0018] The invention is susceptible of numerous embodiments. To further clarify its basic principle, one of these is illustrated in the drawings and will be described below.
[0019] Fig. 1 an expandable tire building drum with an inner layer and a carcass ply;
[0020] Fig. 2 shows the expandable tire building drum during the core fixation process; Fig. 3 shows the tire building drum in the expanded state.
[0021] Figure 1 shows an expandable tire building drum 1 onto which an inner layer 2 and a carcass ply 3 of a pneumatic tire have already been applied. The tire building drum 1 is in a non-expanded state. Bellows 4 and core fixations 5 are arranged to the right and left of the tire building drum 1 in the axial direction of the tire building drum 1. The core fixations 5 are arranged in the radial direction of the tire building drum 1 such that the bellows 4 are located on a radius that is smaller than the radius of the surface of the tire building drum 1. Rollers 6 roll the carcass ply 3 onto the inner layer 2.
[0022] An expansion of the tire building drum 1 can lead to a circumferential variance with regard to the mechanical stress in the inner layer 2 and the carcass ply 3 due to the adhesion of the inner layer 2 and the carcass ply 3 to a bellows 4.
[0023] In order to reduce this variance, as shown in the top of Figure 2, the core fixations 5 of the device 7 known from Figure 1 are moved radially outwards so that the bellows 4 and the inner layer 2 resting thereon as well as the carcass ply 3 are moved radially outwards on the circumference of the core fixation 5. As a result, the axially outer ends of the inner layer 2 and the carcass ply 3 are moved towards one another, and sticking is overcome. Subsequently, as shown in the bottom of Figure 2, the core fixations 5 are moved back to their starting position, with the bellows 4 following the core fixations 5. Due to their rigidity and their adhesion to one another and to the bellows 4, the inner layer 2 and the carcass ply 3 remain in their position; they do not follow the core fixations 5.
[0024] Figure 3 shows the device 7 known from Figure 1 with the tire building drum 1 in the expanded state. The inner layer 2 and the carcass ply 3 rest geometrically uniformly and with uniform tension on the drum shoulder 8, since they were already detached from the bellows 4 before the tire building drum 1 expanded. As shown in the bottom of Figure 3, after the tire building drum 1 has expanded, the rollers 6 move along the drum shoulder 8 to the bellows 4 and increase the uniformity with which the inner layer 2 and the carcass ply 3 rest on the drum shoulder 8.
[0025] Next, bead cores are placed on the carcass ply 3. The bead cores are secured with the core fixations 5 before the bellows 4 are filled for a carcass turn-up. Reference symbols Tire building drum Inner layer Carcass ply Bellows Core fixation Roller device Drum shoulder
Claims
Patent claims 1. A method for producing a pneumatic tire with an inner layer (2), a carcass ply (3), a bead core, a tire belt, and a tread, comprising the following steps: a) Placing the inner layer (2) and the carcass ply (3) on a tire building drum (1) and on a support ring with bellows (4), b) Radially moving core fixings (5) to a larger radius, wherein the radius to which the core fixings (5) are moved is larger than the unexpanded radius of the tire building drum (1), c) Radially moving the core fixings (5) to a smaller radius, wherein the radius to which the core fixings (5) are moved is not larger than the unexpanded radius of the tire building drum (1), d) Forming tire shoulders by expanding the tire building drum, e) Setting a bead core on the carcass ply (3) on the drum shoulder (8), f) Fixing of the bead core with the radially movable core fixation (5),g) wrapping the carcass ply (3) and the inner layer (2) around the bead core by filling a bellows (4), h) completing the green tire with further steps., 2. Method according to claim 1, characterized in that immediately after step a) the carcass ply (3) is rolled onto the inner layer (2).
3. Method according to claims 1 or 2, characterized in that after step d) rollers (6) are moved to a smaller radius in order to apply the inner layer (2) and the carcass ply (3) to the drum shoulder (8).
4. Method according to one of the preceding claims, characterized in that in step b) the core fixings (5) are moved to a radius in order to produce regions of the inner layer (2) which do not rest on the bellows (4), wherein the radius is selected such that the regions of the inner layer (2) which do not rest on the bellows (4) are in the axial direction of the Tire building drum (1) has an extension which is not greater than the area of the inner layer (2) forming the tire shoulder.
5. Method according to one of the preceding claims, characterized in that steps c) and d) are carried out simultaneously.
6. Device (7) for producing a pneumatic tire with an expandable tire building drum (1) and dimensionally stable core fixings (5) arranged axially to the tire building drum (1), characterized in that the device (7) is designed to carry out a method according to one of the preceding claims.
7. Computer program product for operating a device (7) for producing a pneumatic tire, comprising instructions which, when the program is executed by at least one processor unit, cause the latter to carry out the method according to one of claims 1 to 5.