Tire-construction machine

Abstract

The invention relates to a tire-construction machine comprising a construction drum (1), a central region of which has a cylindrical casing (10) that can be expanded radially relative to the axial ends (11) of the construction drum (1), wherein at least one inner layer (2) and a textile layer (3) of a tire blank can be applied onto the construction drum (1) during the course of the construction of the vehicle tires. The tire-construction machine also comprises a rolling device with two rolling discs (4) which rotate in opposite directions, can be moved parallel to the casing (10), can be pressed radially against the casing (10), and can be advanced radially inwards relative to the casing (10) in the region of the axial ends (11). An additional roller (40) is provided on each of the rolling disc (4) inner faces facing each other, said additional roller being rotatably mounted independently of the rolling disc (4) and being radially pressable against the casing (10) when the rolling discs (4) are advanced radially inwards relative to the casing (10).

Description

[0001] Tire building machine

[0002] Description:

[0003] The invention relates to a tire building machine with a building drum which has a cylindrical shell in a central region which can be expanded radially relative to the axial ends of the building drum, wherein at least one inner layer and one fabric layer of a green tire can be applied to the building drum during the production of pneumatic vehicle tires, and with a rolling device with two rolling discs which can be moved in opposite directions and parallel to the shell, can be pressed radially against the shell and can be fed radially inwards relative to the shell in the region of the axial ends.

[0004] Such tire building machines are known and are used to first build up a green tire during the production of a pneumatic vehicle tire by adding the tire components layer by layer and connecting them on the building drum, in order to ultimately form the finished green tire into the desired pneumatic vehicle tire by vulcanization in subsequent production steps.

[0005] An embodiment of such a tire building machine is described by way of example in DE 60306376 T2.

[0006] A typical manufacturing step involves first applying the future inner layer of the pneumatic vehicle tire to the building drum, followed by at least one fabric layer serving as the carcass ply. The core packages are then applied to the resulting composite before further tire components are added.

[0007] Due to the design of the tire building machine with a radially expandable building drum, the contact point between the core and the carcass ply is uncertain. If the rolling device is used to radially inwardly advance the axial ends of the building drum relative to the casing, a process known as edge stitching is achieved. This optimizes this unsystematic behavior and, ideally, can eliminate it completely. The radially inwardly advanced rolling disk ensures a defined path of the inner layer and the fabric ply around the expanded casing. However, this only applies to carcass materials, i.e., fabric plies with a thread path of approximately 90° to the building drum.

[0008] As tire performance improves, fabric plies are increasingly being used whose thread path deviates significantly from 90° to the build drum. As a result, the previously discussed edge stitching technology is only partially applicable, as the rolling discs on both sides of the casing encounter different threads in the fabric ply. This can lead to systematic shifting of the fabric ply over the shoulder of the build drum.

[0009] DE 2019989A1 discloses a rolling device for tire building machines that, in addition to the pair of rolling discs, also features additional pressure rollers that are pivotally mounted to the drum axis via a hydraulic or pneumatic drive. This is mechanically very complex and is not suitable for preventing shifts in the fabric layer when the thread path deviates from 90° to the building drum.

[0010] The object of the invention is to propose a tire building machine of the type mentioned at the outset which can be modified in a simple and easy manner to overcome the disadvantages of the prior art.

[0011] To achieve the stated object, the invention proposes the design of a tire building machine according to the features of patent claim 1.

[0012] Advantageous embodiments and further developments of the invention are the subject of the dependent claims.

[0013] The solution according to the invention provides that an additional roller is provided on each of the mutually facing inner sides of the rolling discs, which additional roller is rotatably mounted independently of the rolling disc and can be pressed radially against the casing when the rolling discs are positioned radially inwards relative to the casing.

[0014] The additional roller provided according to the invention and located on the facing inner sides of the rolling discs ensures that, during the rolling of the inner layer and the fabric layer around the shoulder area, i.e., the transition area between the radially expanded shell and the axial ends of the building drum, the fabric layer is clamped in its position relative to the inner layer and the surface of the shell by the additional roller and prevented from shifting. This makes it possible to apply the so-called edge stitching technology even to fabric layers whose thread path deviates significantly from 90° to the building drum, thus achieving improvements in quality, performance, and production stability.

[0015] According to a proposal of the invention, the rolling discs are each mounted with the associated additional roller on a common axis so as to be independently rotatable, but can be uniformly pressed radially in the direction of the casing or fed beyond it via a corresponding drive.

[0016] According to a further proposal of the invention, the additional rollers are made of hard rubber, with Shore hardness A of 70-100 being considered suitable.

[0017] According to a further proposal of the invention, the additional rollers can either be cylindrical or provided with a radius which causes the diameter of the additional roller to increase in the direction of the associated roller disc.

[0018] According to a further proposal of the invention, the diameter of the additional rollers is dimensioned such that, when pressed against the casing, the associated adjacent rolling disk is at a distance of 1.5 to 5 mm, preferably about 3 mm, from the circumference of the axial end of the building drum. This has the effect that, at the time the additional roller is placed on the expanded casing, the associated rolling disk is positioned at a corresponding distance of 1.5 to 5 mm, preferably 3 mm, above the respective axial end of the building drum, thereby preventing the inner layer and the fabric layer on top from being rolled up by the rolling disk with the axial end of the building drum. The inner layer and the fabric layer on top can therefore continue to slide on the axial end and follow the deformation accordingly.

[0019] The rolling discs modified with additional rollers according to the invention can also be used for all subsequent processing steps in the production of a green tire in a conventional manner and without restrictions. In this respect, the invention is also suitable for simple retrofitting to existing tire building machines.

[0020] Further embodiments and details of the invention are explained below with reference to the drawings illustrating an exemplary embodiment. They show:

[0021] Figure 1 is a schematic representation of a first embodiment of the invention;

[0022] Figure 2 is a schematic representation of a second embodiment of the invention;

[0023] Figure 3 is a schematic representation of a tire building machine;

[0024] Figure 4 is a schematic representation of the edge stitching technology according to the state of the art on a tire building machine according to Figure 3;

[0025] Figure 5 shows another representation of a tire building machine according to the prior art.

[0026] Figures 3 to 5 show a highly simplified representation of a tire building machine used in the production of a green tire for a pneumatic vehicle tire. As can be seen particularly in Figure 5, the tire building machine comprises a substantially cylindrical building drum that is rotationally driven about a central axis R and has, in its central region, a cylindrical shell 10 and two axial ends 11 spaced apart from one another by the cylindrical shell 10. The cylindrical shell 10 is typically made of a rubber material and can be expanded radially relative to the axial ends 11 by application of compressed air, as shown.

[0027] To produce the first layers of a green tire, as shown in Figure 3, the cylindrical shell 10 is initially not pressurized with compressed air while the building drum rotates around the central axis R, so that it is aligned with the axial ends 11. In this state, the future inner layer 2 is fed and wound onto the surface of the building drum, followed by a fabric layer 3, which forms the future carcass ply.

[0028] Before the core packages (not shown here) are subsequently applied to the edge regions of the inner layer 2 and fabric layer 3 in the region of the axial ends 11, the jacket 10 is pressurized with compressed air and radially expanded so that it assumes a larger diameter than the axial ends 11. In the region of the shoulder of the jacket 10, where it transitions into the axial ends 11, an undefined angular profile of the inner layer 2 and the fabric layer 3 occurs, with the angle of departure from the jacket 10 being represented by a in Figure 4.If the fabric layer 3 has a thread path that is essentially aligned at an angle of 90° to the building drum, the inner layer 2 and the fabric layer 3 can be applied to the radially expanded end region of the casing 10 in each region of the shoulder of the casing 10 using a rolling device on the tire building machine with two rolling discs 4 that can be moved in opposite directions parallel to the casing 10 and pressed radially against the casing 10, and the angle α can be minimized or ideally completely eliminated, which is referred to as edge stitching technology. However, if the fabric layer 3 has a thread path that deviates significantly from the angle of 90° to the building drum, as is the case with modern performance tires, the rolling disc 4 engages various threads of the fabric layer 3 and this can lead to a systematic displacement of the fabric insert 3 over the drum shoulder.

[0029] In order to counteract this problem, the rolling disc 4 is modified in a first embodiment shown in Figure 1 in such a way that an additional roller 40 is provided on each of the mutually facing inner sides of the rolling discs 4, which additional roller is arranged on a common axis with the rolling disc 4, but wherein the rolling disc 4 and the additional roller 40 are rotatably mounted independently of one another.

[0030] The positioning and dimensioning of the additional roller 40 for the respective rolling disk 4 is selected such that when the rolling disk 4 is fed radially inwards towards the axial end 11 relative to the casing 10, the additional roller 40 rests circumferentially on the shoulder region of the casing 10 and can be pressed there, so that the fabric layer 3 resting on the casing 10 and optionally also the inner layer 2 are clamped and held between the additional roller 40 and the casing 10 and are prevented from shifting relative to one another.

[0031] In addition, the diameter of the additional roller 40 is dimensioned such that, when pressed against the casing 10, it serves as a stop, and the adjacent roller disc 4 has a circumferential distance X of preferably approximately 3 mm from the axial end 11 of the building drum. This prevents the inner layer 2 and the fabric layer 3 from being connected to the axial end 11 of the building drum by the roller disc 4, allowing them to continue to slide on the surface of the axial end 11 in accordance with the material flow.

[0032] The additional roller is preferably made of hard rubber with a Shore A hardness of approximately 70-100 and, in the illustrated embodiment according to Figure 1, can have a radius such that the diameter increases in the direction of the associated rolling disc 4 in accordance with the course of the inner layer 2 and the fabric layer 3 in the shoulder region of the casing 10.

[0033] Alternatively, as shown in Figure 2, it can also be provided that the additional roller 40 is cylindrical.

[0034] List of reference symbols:

[0035] 1 : Building drum

[0036] 2: Inner layer 3: Fabric layer

[0037] 4: Rolling disc

[0038] 10: Coat

[0039] 11 : axial end R: central axis

[0040] X: Distance

Claims

Patent claims:

1. Tire building machine with a building drum (1) which has a cylindrical casing (10) in a central region which can be expanded radially relative to the axial ends (11) of the building drum (1), wherein at least one inner layer (2) and one fabric layer (3) of a green tire can be applied to the building drum (1) during the production of pneumatic vehicle tires, and with a rolling device with two rolling discs (4) which can be moved in opposite directions and parallel to the casing (10), can be pressed radially against the casing (10) and can be fed radially inwards relative to the casing (10) in the region of the axial ends (11), characterized in that on each of the mutually facing inner sides of the rolling discs (4) an additional roller (40) is provided which is rotatably mounted independently of the rolling disc (4) and, when the rolling discs are fed radially inwards relative to the casing (10), (4) can be pressed radially onto the casing (10).

2. Tire building machine according to claim 1, characterized in that the rolling discs (4) are each rotatably mounted with the associated additional roller (40) on a common axis independently of one another.

3. Tire building machine according to claim 1 or 2, characterized in that the additional rollers (40) are made of hard rubber with a Shore A hardness of 70 to 100.

4. Tire building machine according to one of claims 1 to 3, characterized in that the additional rollers (40) are cylindrical or with a diameter increasing in the direction of the associated rolling disc (4).

5. Tire building machine according to one of claims 1 to 4, characterized in that the diameter of the additional rollers (40) is dimensioned such that, when pressed against the casing (10), the associated rolling disc (4) has a distance of 1.5 to 5 mm from the circumference of the axial end (11) of the building drum (1).

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