Method and system for cleaning the inner surface of a tire

Abstract

A method and system (1) for cleaning an inner surface (2) of a tire (3) includes the steps of: emitting a laser beam (9) directed toward the inner surface (2) with an emitter device (8), applying a first surface energy density to at least a first annular zone (A) of the inner surface (2) with the laser beam (9) for deeper cleaning, and applying a second surface energy density, lower than the first surface energy density, to at least a second annular zone (B) of the inner surface (2) with the laser beam (9) for less thorough cleaning.

Description

[Technical field]

[0001] The present invention relates to a method and system for cleaning the inner surface of a tire. [Background technology]

[0002] In recent years, tire development has been directed towards tires with inner linings manufactured with a sealant intended to seal punctures. The sealant usually has a high level of viscosity to ensure both a sealing action against the hole and its stability inside the lumen whatever the conditions of the tire. The sealant is applied to the inner surface of the tire before vulcanization (i.e. above the inner liner) in the areas of the tire that come into contact with the road (i.e. areas of the tire where punctures can potentially occur). In particular, the sealant is applied to the tread and partially to the sidewalls.

[0003] In recent years, tire development has also been directed towards tires with an internal sound-absorbing material (generally a sponge) for reducing the noise generated by the tire rolling on the road surface. The sound-absorbing material is applied to the inner surface of the already vulcanized tire (i.e. above the inner liner) and is bonded to the inner surface of the tire, especially in the tread (i.e. the area of ​​the tire that comes into contact with the road), and possibly also in part of the sidewalls.

[0004] Before applying the sealant or sound absorbing material to the inner surface (consisting of the inner liner) of the tire, the inner surface must be cleaned to remove dirt and processing residues (e.g. residues from a release agent applied to the inner wall of the vulcanization mold) to ensure optimal adhesion of the sealant or sound absorbing material to the inner surface.

[0005] Patent applications WO2017082162A1 and EP3281810A1 describe a system for cleaning the inner surface of a tire, in which a laser emitter is inserted into an already vulcanized tire and emits a laser beam that is directed toward the inner surface of the tire while the tire rotates at a constant speed. The laser emitter is gradually moved axially (i.e. along the central axis of the tire's rotation) so that the laser beam progresses through a spiral that sweeps the entire inner surface of the tire from start to finish.

[0006] Patent applications WO2017082162A1 and EP3281810A1 describe cleaning the entire inner surface of a tire completely and in the same way. However, in this way the cleaning cycles are rather long. In order to have an hourly productivity suitable to the requirements of the manufacturing plant, it is therefore necessary to provide a large number of cleaning stations, all of which work in parallel, with an associated increase in cost and size. To solve this problem (i.e. to make the cleaning cycles faster), patent applications EP3175974A1 and EP3175975A1 describe generating a laser beam that cleans the inner surface of the tire in strips, i.e. alternating between uniformly cleaned strips and completely uncleaned strips, following a non-continuous, non-linear (i.e. wavy) path. However, this solution has the disadvantage that optimal adhesion of the sealant or sound-absorbing material to the inner surface is not always obtained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] WO2017082162A1 [Patent Document 2] EP3281810A1 [Patent Document 3] EP3175974A1 [Patent Document 4] EP3175975A1 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a method and a system for cleaning the inner surface of a tire, which does not have the above-mentioned drawbacks and in particular allows for rapid cleaning cycles and at the same time ensures optimal adhesion of the sealing agent or sound-absorbing material to the inner surface under all conditions. [Means for solving the problem]

[0009] According to the present invention there is provided a method and system for cleaning the inner surface of a tire as defined in the appended claims.

[0010] The claims describe preferred embodiments of the invention and form an integral part of this specification.

[0011] The present invention will now be described with reference to the accompanying drawings which show exemplary, non-limiting embodiments. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic side view, with parts removed for clarity, of a cleaning system made in accordance with the present invention; [Diagram 2] FIG. 2 is a schematic front view, with parts removed for clarity, of the cleaning system of FIG. 1; [Diagram 3] 2 is a schematic cross-sectional view of a portion of a tire highlighting the differentiated cleaning areas created by the cleaning system of FIG. 1; [Figure 4] A variation of the schematic diagram of FIG. 3 is shown. [Diagram 5] A variation of the schematic diagram of FIG. 3 is shown. [Figure 6] A variation of the schematic diagram of FIG. 3 is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In Figures 1 and 2, in their entirety, the numeral 1 denotes a cleaning system 1 for cleaning (at least) a part of an inner surface 2 (consisting of an inner liner) of a tire 3, before the application of a sealant or sound absorbing material. In other words, the tire 3 has a toroidal shape bounded by an outer surface and by an inner surface 2 opposite the outer surface, the sealant or sound absorbing material being applied to (at least) a part of the inner surface 2. Before the sealant or sound absorbing material can be applied to the inner surface 2 of the tire 3, the inner surface 2 needs to be cleaned to remove dirt and processing residues (for example residues from a release agent applied to the inner wall of the vulcanization mold).

[0014] The cleaning system 1 comprises a support device 4 suitable for supporting a tire 3 arranged in a vertical position and also suitable for rotating the tire 3 about a rotation axis 5 coinciding with a central axis of symmetry. According to a preferred embodiment, the support device 4 comprises an extending gripper rotatably mounted and suitable for internally gripping the tire 3. Alternatively (as shown in the accompanying drawings), the support device 4 comprises side rails (not shown) for stably holding the tire 3 in a vertical position and motorized rollers (schematically illustrated). The tire 3 rests on and is driven by the motorized rollers. According to a further embodiment, the support device 4 is of a different shape and is suitable for supporting a tire 3 arranged not in a vertical position but instead in a horizontal position.

[0015] The cleaning system 1 comprises a position sensor 6 suitable for determining the angular position of the tire 3 about its axis of rotation 5. The position sensor 6 may for example be an angle encoder coupled to one of the motorized rollers of the support device 4. Alternatively, the position sensor 6 may read out the displacement of the tire 3 directly.

[0016] The cleaning system 1 may comprise a camera 7, which faces the outer surface of the sidewall of the tire 3 and is suitable for reading a graphical identification code (typically a barcode or similar) affixed to the same sidewall. In the case of the tire 4, the graphical identification code is always affixed in the same position (also in the same angular position). Thus, when the camera 7 detects the presence of a graphical identification code, the corresponding angular position of the tire 3 around the axis of rotation 5 is determined accordingly, in order to obtain an absolute angular reference for the angular position of the tire 3 around the axis of rotation 5. The support device 4 comprises an angular position sensor (usually an encoder) which detects the angular position of the tire 2 while it is rotating.

[0017] The cleaning system 1 comprises an emitter device 8 capable of emitting a laser beam 9 powerful enough to sublimate (vaporize) at least a part of foreign matter present on the inner surface 2 (consisting of the inner liner) of the tire 3. Such foreign matter may include release agents (applied inside the vulcanization mold) that may inhibit the subsequent manufacturing process. By appropriately modulating the laser beam 9, any damage to the inner surface 2 (consisting of the inner liner) of the tire 3 can be avoided. The laser beam 9 can thus clean the inner surface 2 of the tire 3 without running the risk of damaging it.

[0018] Furthermore, the cleaning system 1 comprises a handling device 10, which performs the relative movement between the emitter device 8 and the tire 2 carried by the support device 4 (moving the support device 4 carrying the tire 2 and keeping the emitter device 8 stationary, or else moving the emitter device 8 and keeping the support device 4 carrying the tire 2 stationary). At the start and end of a cleaning cycle, the handling device 10 positions the emitter device 8 on the inside and outside of the tire 3, respectively. Meanwhile, during a cleaning cycle, the movement device 10 moves the emitter device 8 axially (i.e. parallel to the rotation axis 5) with respect to the tire 2 from one side of the tire 3 to the other side of the tire 3, allowing the laser beam 9 emitted by the emitter device 8 to clean the entire inner surface 2 of the tire 3.

[0019] According to what is shown in Fig. 2, the handling device 10 may comprise a support arm 11 supporting the emitter device 8 at one end, and an actuator 12. The actuator 12 translates the support arm 11 axially (i.e. parallel to the axis of rotation 5). According to alternative embodiments, the handling device 10 may comprise a robotic arm with more degrees of freedom, if required, for the initial insertion of the emitter device 8 into the tire and the subsequent removal of the emitter device 8 from the tire.

[0020] According to a possible embodiment, the handling device 10 holds the emitter device 8 stationary while cleaning a circular strip (obviously having a width equal to the width, i.e. to the axial dimension of the laser beam 9) of the inner surface 2, and moves the emitter device 8 axially (in one step) only between the end of the cleaning of a circular strip of the inner surface 2 and the start of the cleaning of the next adjacent circular strip of the inner surface 2. In other words, a plurality of circular strips of the inner surface 2 are cleaned independently between them, arranged next to each other (generally with a certain mutual overlap, i.e. with a new circular strip more or less overlapping the adjacent one). According to an alternative embodiment, the moving device 10 moves the emitter device 8 axially and continuously in order to clean a single continuous strip of the inner surface 2 having a spiral shape (i.e. without seams) (also in this case each loop of the spiral is more or less overlapping the previous spiral).

[0021] The cleaning system 1 comprises a control unit 13 which supervises the operation of the same cleaning system 1 and, among other things, controls the activation and deactivation of the emitter device 8, regulates the rotational speed imparted by the support device 4 and controls the axial translational movement imparted by the displacement device 10.

[0022] In use, once a new tire 3 to be cleaned is mounted on the support device 4, the handling device 10 is operated to insert the emitter device 8 inside the tire 3 to be cleaned (or to position the tire 3 to be cleaned around the emitter device 8). At this point, the support device 4 rotates the tire 3 about its rotation axis 5, and the emitter device 8 is then operated to emit a laser beam 9 that is directed towards the inner surface 2 of the tire 3. At the same time, the handling device 10 is operated to create a relatively slow axial translation between the emitter device 8 and the tire 2, such that the laser beam 9 can clean the entire inner surface 2 of the tire 3, from one end to the other. At the end of the cleaning cycle, the emitter device 8 is stopped and the handling device 10 is then operated to pull the emitter device 8 out of the tire 3 (or to remove the tire 3 from the emitter device 8). Thus, the clean tire 3 can be removed from the supporting device 4 and a new tire 3 to be cleaned can be mounted on the supporting device 4, thereby starting a new cleaning cycle.

[0023] With respect to that shown in FIG. 3, deeper cleaning is performed within (at least) annular zone A (consisting of a series of circular strips or spirals of constant width, adjacent and partially overlapping between them) of the inner surface 2, by applying a laser beam 9 (typically 1000 joules / cm 2 Further, less thorough cleaning is performed within (at least) annular zone B (which also consists of a series of circular strips or spirals of constant width, adjacent and partially overlapping between them) of the inner surface 2 by applying, with the laser beam 9, a second surface energy density lower than the first surface energy density to the annular zone B. By way of example, the second surface energy density (applied to zone B) is between 35% and 50% of the first surface energy density (applied to zone A).

[0024] As shown in the accompanying drawings, the annular zone A is disposed adjacent to the sidewall (i.e., the outer edge of the tire 3) of the tire 3 so as to be disposed at both ends of the annular zone B. (i.e., the annular zone B is disposed inside the annular zone A, i.e., the annular zone B is surrounded on the left and right by the annular zone A.)

[0025] In the embodiment shown in Figure 3, the annular zone B is located in the center of the tire 3, i.e. it occupies the entire center of the tire 3 without interruption. In the alternative embodiment shown in Figure 4, the annular zone A is located both near the sidewall and in the center of the tire 3. Thus, zone B is located inside two semi-central bands on either side of the centrally located annular zone A.

[0026] In an alternative embodiment shown in Figures 5 and 6, an intermediate cleaning cycle is performed inside annular zone C (consisting of a series of circular strips or spirals of constant width, adjacent and partially overlapping between them) of the inner surface 2, applying with the laser beam 9 inside the annular zone C a third surface energy density lower than the first surface energy density (applied inside zone A) and higher than the second surface energy density (applied inside zone B). By way of example, the second surface energy density (applied inside zone C) is between 60% and 80% of the first surface energy density (applied inside zone A). The annular zone C is interposed between annular zone A and annular zone B.

[0027] In the embodiments shown in the accompanying drawings, two or three zones A, B, and C are provided, each having a different cleaning degree (i.e. a different surface energy density applied by the laser beam 9). According to other embodiments, not shown, more than three (e.g. four, five, six, etc.) zones A, B, and C may be provided, each having a different cleaning degree (i.e. a different surface energy density applied by the laser beam 9).

[0028] According to a preferred embodiment, the intensity of the laser beam 9 emitted by the emitter device 8 is always kept constant (i.e. the emitter device 8 always operates at its rated power, i.e. maximum possible power, so as to always utilize all the potential of the emitter device 8). Thus, in order to increase or decrease the surface energy density applied by the laser beam 9 to the inner surface 2, the rotational speed of the tire 3 is decreased or increased about the axis of rotation 5.

[0029] Indeed, for the same intensity of the laser beam 9 emitted by the emitter device 8, the faster the tire 3 rotates about its axis of rotation 5, the greater the amount of energy (i.e., typically Joules / cm2) that is radiated onto the surface area. 2 The surface energy density (measured in micrometers) is reduced.

[0030] According to a possible embodiment, one pass (circular strip or spiral) of the laser beam 9 is partially overlapped on a subsequent pass (circular strip or spiral) of the laser beam 9, so that the laser beam 9 passes (at least partially) where the previous one passed. In this case, it is possible to vary the degree of overlap between the various zones A, B and C. In particular, the annular zone A has a first degree of overlap that is greater than the second degree of overlap of the annular zone B. On the other hand, the annular zone C has a third degree of overlap between the first degree of overlap of the annular zone A and the second degree of overlap of the annular zone B. By way of example, the first degree of overlap of the annular zone A is between 45% and 75%, the second degree of overlap of the annular zone B is between 15% and 35% and the third degree of overlap of the annular zone C is between 30% and 50%. (An overlap of 0% corresponds to no overlap, while an overlap of 100% corresponds to total overlap.) These values ​​are merely examples and can be different.

[0031] It is important to emphasize that there are no uncleaned portions of the inner surface 2 inside the axial annular zone A, i.e. the uncleaned portions of the inner surface 2 are only found outside the axial annular zone A. In other words, cleaning of the inner surface 2 involves cleaning in a differentiated manner (i.e. in the cleaner portions, zone A, and the less clean portions, zone B) of the entire inner surface 2 affected by the cleaning cycle. However, in both cases the entire area is cleaned without leaving any unclean "holes".

[0032] According to a preferred embodiment, the emitter device 8 is operated to continuously emit the laser beam 9, in order to achieve continuous cleaning, i.e. along the circular band, without interruption. According to an alternative embodiment, the emitter device 8 is operated to intermittently emit the laser beam 9, in order to perform intermittent cleaning ("checkerboard"), i.e. alternating clean and unclean areas along the circular band.

[0033] The embodiments described herein can be combined among themselves without departing from the scope of protection of the present invention.

[0034] The cleaning system 1 described above has many advantages.

[0035] First, the above-described cleaning system 1 can very quickly clean the inner surface 2 of the tire 3. Several experimental tests have shown that the above-described cleaning system 1 can be up to 50-60% faster than similar known cleaning systems.

[0036] Furthermore, the above-described cleaning system 1 ensures optimal adhesion of the sealing agent or sound absorbing material to the inner surface 2 .

[0037] Finally, the above-described cleaning system 1 is essentially simple and inexpensive to implement when compared to similar known cleaning systems, in that it requires no hardware changes (or at least only minor hardware changes) and only software updates. [Explanation of symbols]

[0038] 1. Cleaning System 2. Inner Surface 3 Tires 4 Support device 5 Rotation axis 6 Position Sensors 7. Camera 8 Emitter device 9 Laser Beam 10 Handling Equipment 11 Support arm 12 Actuator 13. Control Unit A Circular Zone B Circular Zone C Circular Zone

Claims

1. A method for cleaning an inner surface (2) of a tire (3), comprising the steps of emitting a laser beam (9) directed towards said inner surface (2) using an emitter device (8), The method for cleaning comprises: a further step of applying a first surface energy density to said first annular zone (A) of said inner surface (2) with said laser beam (9) to perform deeper cleaning at least within said first annular zone (A); and the further step of applying, within at least a second annular zone (B) of said inner surface (2), with said laser beam (9) to said second annular zone (B) a second surface energy density which is different from zero and lower than said first surface energy density to effect a less thorough cleaning.

2. 2. The method for cleaning of claim 1, wherein the second surface energy density is between 35% and 50% of the first surface energy density.

3. 3. A method for cleaning according to claim 1 or 2, characterized in that said first annular zone (A) is arranged adjacent to the sidewall of said tire (3) so as to be located at both ends of said second annular zone (B).

4. 3. A method for cleaning according to claim 1 or 2, wherein said second annular zone (B) is arranged in the centre of said tyre (3).

5. 3. A method for cleaning according to claim 1 or 2, wherein said first annular zone (A) is located both near the sidewall of said tire (3) and in the center of said tire (3).

6. 3. The method for cleaning according to claim 1 or 2, comprising the further step of applying a third surface energy density within at least a third annular zone (C) of the inner surface (2) with the laser beam (9) to said third annular zone (C), the third surface energy density being lower than the first surface energy density and higher than the second surface energy density to perform intermediate cleaning.

7. 7. A method for cleaning according to claim 6, wherein said third annular zone (C) is interposed between said first annular zone (A) and said second annular zone (B).

8. 7. The method for cleaning of claim 6, wherein the third surface energy density is between 60% and 80% of the first surface energy density.

9. a further step of rotating said tire (3) about an axis of rotation (5) using a support device (4); the further step of constantly keeping constant the intensity of the laser beam (9) emitted by the emitter device (8); A method for cleaning according to claim 1 or 2, comprising the further step of increasing or decreasing the surface energy density applied by the laser beam (9) to the inner surface (2) when decreasing or increasing the rotational speed of the tyre (3).

10. 3. A method for cleaning according to claim 1 or 2, wherein there are no uncleaned parts of the inner surface (2) within the first annular zone (A) in the axial direction, i.e. uncleaned parts of the inner surface 2 are found only outside the first annular zone (A) in the axial direction.

11. 3. The method for cleaning according to claim 1 or 2, comprising the further step of emitting said laser beam (9) continuously, without interruption, to achieve continuous cleaning, i.e. along a circular band.

12. 3. The method for cleaning according to claim 1 or 2, comprising the further step of emitting the laser beam (9) intermittently to perform intermittent cleaning, i.e. alternating clean and unclean areas along a circular band.

13. the further step of partially overlapping one pass of said laser beam (9) with a next pass of said laser beam (9); 3. A method for cleaning according to claim 1 or 2, comprising the further step of varying a degree of overlap between said first annular zone (A) and said second annular zone (B).

14. 14. The method for cleaning according to claim 13, wherein the first annular zone (A) has a first degree of overlap that is higher than a second degree of overlap of the second annular zone (B).

15. A system (1) for cleaning an inner surface (2) of a tire (3), comprising: an emitter device (8) configured to emit a laser beam (9) directed towards said inner surface (2); and a control unit (13), The control unit (13) applying a first surface energy density to said first annular zone (A) of said inner surface (2) with said laser beam (9) to perform deeper cleaning within at least said first annular zone (A); 1. A system (1) for cleaning, characterized in that, within at least a second annular zone (B) of the inner surface (2), the system is configured to apply, by means of the laser beam (9), a second surface energy density to the second annular zone (B) that is not zero and is lower than the first surface energy density, to perform a less thorough cleaning.

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