Method for regrooving a tyre tread
The regrooving process and machine facilitate precise alignment of grooves to the existing tread pattern, addressing the inefficiencies of manual methods and improving tire performance through pattern alignment.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MICHELIN & CO (CIE GEN DES ESTAB MICHELIN)
- Filing Date
- 2025-11-06
- Publication Date
- 2026-05-21
Smart Images
Figure EP2025082085_21052026_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] Tire tread regrooving process
[0003] technical field
[0004] The invention belongs to the field of tires, and more specifically relates to a method of regrooving a tire tread, and the corresponding regrooving machine.
[0005] Technological background
[0006] A tire has a tread pattern consisting of raised sections in the rubber, such as grooves and peaks, which gives the tire desired properties, such as water evacuation or road grip. Tire use causes abrasion of the tread rubber, which gradually leads to erosion of the tread pattern. The peaks become shallower and the grooves shallower. The tire's properties, conferred by the tread pattern, are progressively altered until they are no longer satisfactory. To monitor the acceptable level of tire wear, wear indicators are present in depressions such as grooves, generally taking the form of localized raised sections at the bottom of the tread.The condition of the tire tread is considered unsatisfactory when the distance between the top of the tread and the wear indicator becomes too small.
[0007] A tire with excessively worn tread can no longer be used to power a vehicle. As a cost-saving measure, and to allow for reuse, the practice of regrooving the tread pattern has been implemented. Even though part of the tread corresponding to the crests of the tread pattern has disappeared, the remaining tread still retains sufficient thickness to create grooves that recreate a tread pattern, restoring the tire's properties and allowing its reuse. Tire regrooving, therefore, is an operation that involves removing rubber from the existing tread block to restore tread depth, following a specific pattern that may replicate the previous one or be different.
[0008] This regrooving operation is usually performed manually, using a regrooving tool operated by a person, as described, for example, in patent document EP 2025 501 A1. The regrooving tool comprises a holder with a gripping portion by which the operator holds the tool. The holder carries a U-shaped blade, heated by the flow of an electric current, protruding from a bearing surface on the holder. The operator presses the regrooving tool against the surface of the tire tread, driving the blade into the tread rubber until the bearing surface is in contact with the tread surface. By moving the tool with the bearing surface against the tread surface, the operator cuts a groove or channel into the tread rubber.The depth of the resulting grooves corresponds to the protrusion of the blade beyond the contact surface. A sculpted pattern is thus recreated on the tread.
[0009] Such manual regrooving is a tedious and physically demanding task. A regrooving machine has already been proposed for regrooving a profile with at least one groove in a tire tread, comprising a tire housing to hold a tire on a drive axle, which is coaxial with an axis of rotation of the tire, drive means for rotating a tire received by the tire housing around the axis of rotation during a cutting operation, a cutting device which includes a cutting head with a blade and a support device to press the cutting head during a cutting operation on the tread of the tire received by the tire housing, so that a blade is in the groove of the tread.
[0010] To achieve the expected performance from a regrooved tire, the grooves created during the regrooving process must follow the pattern dictated by the regrooving design. Manual regrooving only allows for very simple patterns, which do not allow for optimal performance. Using a regrooving machine allows for more complex regrooving patterns, thus resulting in better performance for the regrooved tire.
[0011] The grooves are most effective when they are located in the right places on the tread, and when the regrooving pattern they follow is correctly positioned relative to the tire's tread. However, tire positioning is not always precise, and the tire's shape can vary, particularly because wear results in a reduction of rubber thickness. Therefore, it is not always easy to regroove the grooves in the right place. Furthermore, a tire requiring regrooving usually has some residual tread pattern, resulting from the more or less pronounced wear of the original tread pattern. It can be advantageous to align the regrooving grooves with any remaining depressions in the tread pattern.If the re-grooving grooves do not take into account the sculpture residue, the re-grooved sculpture may then include unwanted superfluous reliefs compared to the desired re-grooving pattern.
[0012] Presentation of the invention
[0013] The invention aims to provide a regrooving process enabling the regrooving of a tread pattern on a tire with grooves whose positions correspond best to the expected regrooving pattern, allowing alignment between the tread pattern residue and the regrooving pattern.
[0014] To this end, the invention proposes a method for regrooving the tread of a tire, the tire having a tread residue, the method comprising:
[0015] - a display of a representation of a re-grooving pattern;
[0016] - a modification of the positioning of the representation of the re-carving pattern relative to the sculpture residue, reducing an overlap between the representation of the re-carving pattern and the sculpture residue; then
[0017] - a regrooving of the tire by creating grooves at positions affected by the positioning of the representation of the regrooving pattern.
[0018] The process according to the invention is advantageously and optionally complemented by the following various features taken alone or according to any of their various technically possible combinations:
[0019] - Modifying the positioning of the re-grooving pattern representation includes moving the re-grooving pattern representation and / or deforming the re-grooving pattern representation.
[0020] - The representation of the re-grooving pattern is an image in which geometric elements correspond to the grooves to be cut.
[0021] - The representation of the regrooving pattern is displayed on a screen simultaneously with a visualization of a tire tread.
[0022] - The representation of the regrooving pattern is projected onto the tread of the tire.
[0023] - The sculpture residue includes re-excavation pits, the re-excavation pattern includes re-excavation pit markings, and the modification of the positioning of the representation of the re-excavation pattern includes a reduction of an overlap offset between the re-excavation pits of the sculpture residue, and the corresponding markings of the representation of the re-excavation pattern.
[0024] - Modifying the positioning of the regrooving pattern representation involves moving the tire.
[0025] The invention also proposes a regrooving machine comprising a rotating axis carrying the tire, a regrooving blade configured to make grooves in a tread surface of the tire, means for displaying a representation of a regrooving pattern, means for modifying the positioning of the representation of the regrooving pattern relative to a tread residue on the tread surface of the tire, and means for controlling regrooving taking into account the positioning of the representation of the regrooving pattern, the regrooving machine being configured to implement the process as previously described.
[0026] The regrooving machine according to the invention is advantageously and optionally supplemented by the following various features, taken alone or according to any of their technically possible combinations:
[0027] - The means for displaying a representation of a regrooving pattern include a camera configured to acquire a visualization of the tire tread, and a screen configured to simultaneously display the representation of the regrooving pattern with the visualization of the tire tread.
[0028] - The means for displaying a representation of a regrooving pattern include a projector configured to project the representation of the regrooving pattern onto the tread of the tire.
[0029] Presentation of the figures
[0030] Other features, purposes and advantages of the invention will become apparent from the detailed description below, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings, given by way of non-limiting examples and on which:
[0031] - Figure 1 schematically shows an example of a re-grooving machine, according to one possible embodiment of the invention;
[0032] - Figure 2 schematically shows an example of a visualization of a tire tread, according to a possible embodiment of the invention; - Figure 3 schematically shows a representation of the regrooving pattern showing an overlap offset with the tread residue;
[0033] - Figure 4 schematically shows the representation of the re-carving pattern superimposed with the sculpture residue.
[0034] Across all figures, similar elements bear identical references.
[0035] Detailed description
[0036] In the accompanying figures, the various geometric orientations are defined in an XYZ coordinate system, defined by a longitudinal or circumferential direction X, tangent to the circumference of the tire along its direction of travel, a transverse or axial direction Y, parallel to the axis of rotation of the tire, and a radial direction Z, perpendicular to the axis of rotation of the tire. A radial plane is defined as a plane containing the axis of rotation of the tire and extending along a radial direction Z and a transverse direction Y. A radial half-plane is defined as a plane bounded by the axis of rotation of the tire and extending along the transverse direction Y and a radial direction Z from the axis of rotation of the tire.
[0037] The method uses a regrooving machine, as in the example illustrated in Figure 1. Such a regrooving machine 100 comprises a rotating shaft 102 carrying the tire 1 along its axis of rotation extending in the transverse direction Y, and a tool holder 104 capable of accommodating and moving a measuring instrument and / or a regrooving blade facing the tread 2 of the tire 1. The tool holder 104 is preferably aligned with the rotating shaft 102 in a radial direction Z, and is movable in the radial direction Z towards the rotating shaft 102, and is preferably movable in the transverse direction Y in order to move the instrument or the blade across the width of the tire 1. The rotating shaft 102 carrying the tire 1 is preferably movable at least in the vertical radial direction Z, and is configured to drive the tire 1 in rotation.
[0038] To perform the regrooving, the regrooving machine 100 carries a regrooving blade 106 whose position relative to the tire's axis is determined by the height mapping. The tire 1 is rotated around the rotating axis 102 that supports it, and the regrooving blade 106, for example U-shaped, is positioned so that its tip cuts the rubber on the surface of the tread 2. A groove is then formed. If the regrooving blade 106 is held fixed, the groove is circumferential around the tire 1. The regrooving blade 106 can also be moved during regrooving, particularly in the transverse Y direction, to create a groove with a transverse component.To move from one groove to another, it is sufficient to raise the regrooving blade 106 in the radial direction Z, then to change the relative position between the tire 1 and the regrooving blade 106, for example by transverse translation of the tool holder 104 carrying the regrooving blade 106, by rotation of the regrooving blade 106, and / or rotation of the tire 1, to make a new groove on the surface of the tread 2.
[0039] The regrooving machine 100 also includes means 108 for displaying a representation of a regrooving pattern. The display means 108 for a representation of a regrooving pattern may include a camera configured to acquire a visualization of the tread 2 of the tire 1, typically a camera acquiring a video stream. The display means 108 may also include a screen configured to simultaneously display the representation of the regrooving pattern with the visualization of the tread 2 of the tire 1. The display means 108 for a representation of a regrooving pattern may include a projector configured to project the representation of the regrooving pattern directly onto the tread 2 of the tire 1.
[0040] Figure 2 shows an example of a tread 2 of a tire 1 whose tread pattern has been worn by tire rolling. The use of a tire 1 results in progressive wear and material loss in the areas in contact with the rolling surface, typically the road. Due to the tread pattern, it is the crests 10 of the tread, i.e., the areas between the grooves 8, that wear down and progressively lose height. Conversely, the tread bases, i.e., the bottoms of the grooves 8, are not normally in contact with the rolling surface and therefore wear much less. The distance between the crests 10 and the bottoms of the grooves 8 is thus reduced, and the grooves 8 become shallower. It frequently happens that the wear is not uniform across the tire, and therefore some areas of the tread 2 exhibit a more pronounced reduction in the depth of the grooves 8 compared to other areas.
[0041] The process aims to regroove the tread of the tire 1 to create grooves that allow the tread to reach depths of 8 suitable for giving the tire 1 properties that enable its reuse. The regrooving pattern is chosen according to the tire 1, in particular its type. The regrooving pattern defines at least the grooves to be made in the tread. The regrooving pattern can also define the paths of the regrooving blade 106, including when the regrooving blade 106 does not cut into the rubber of the tire 1. The tire 1 is mounted on the regrooving machine 100 in the regrooving position, on the rotating axis 102. A representation 10 of a regrooving pattern is then displayed.Representation 10 of the regrooving pattern is an image in which geometric elements correspond to the grooves to be cut to create the regrooving pattern on the tread 2. Representation 10 of a regrooving pattern is displayed in a configuration which allows simultaneous and in the same place visualization of the carving residue.
[0042] Figure 3 shows an example of the display of representation 10 of the regrooving pattern. Preferably, representation 10 of the regrooving pattern comprises a set of lines, here representing the grooves to be cut and thus the paths of the regrooving blade 106. The regrooving pattern comprises a repetition of an elementary motif in the circumferential direction X. In this example, the regrooving pattern defines the paths of the regrooving blade, including when the regrooving blade 106 is not cutting into the tire rubber. Thus, the regrooving pattern may have transverse ends 12 outside the tread, which can correspond to the path of the regrooving blade 106 when it moves relative to the tread 2 without cutting.The regrooving pattern may also include positioning markings that do not correspond to the grooves to be cut or the paths of the regrooving blade 106, but rather serve to correctly position the representation 10 of the regrooving pattern. Typically, a positioning marking is a visual indication related to a location on the tire 1, which allows for the estimation of an overlap offset. For example, the tread residue may include regrooving holes, and the regrooving pattern may include regrooving hole markings. In a zero-offset overlap, the regrooving hole markings cover the regrooving holes. The gap between the regrooving hole markings and the regrooving holes indicates the overlap offset. Other positioning markings may be used, provided that these positioning markings allow for the estimation of an overlap offset.
[0043] The display as illustrated in Figure 3 can be performed on a display screen viewed by the operator. In this case, a camera forming part of the display means 108 acquires a visualization such as an image or a video stream of the tread 2 of the tire 1. The screen simultaneously displays the representation 10 of the regrooving pattern with the visualization of the tread 2 of the tire 1, preferably in superposition. Typically, the representation 10 of the regrooving pattern has gaps in the fill, so that it is possible to distinguish the visualization of the tread 2 through the representation 10 of the regrooving pattern, which is placed over the visualization of the tread 2.It is also possible to foresee that the upper layer in representation 10 of the regrooving pattern and the visualization of the tread 2 of the tire 1 may have a transparency allowing the lower layer to be seen.
[0044] Alternatively, the display as illustrated in Figure 3 can result from projecting the representation 10 of the regrooving pattern directly onto the tread 2. In this case, a projector forming part of the display means 108 projects the representation 10 of the regrooving pattern. There is then a superimposition between the representation 10 of the regrooving pattern and the visualization of the tread 2 of the tire 1 which serves as a support.
[0045] Because of the typically very dark character of a tread 2, the representation 10 of the regrooving pattern preferably features very light or bright shades.
[0046] In the example of Figure 3, a 16-fold overlap is observed between the representation 10 of the regrooving pattern and the remaining tread pattern 2. This 16-fold overlap is all the more noticeable when the spatial organization of the representation 10 of the regrooving pattern presents similarities with the original tread pattern, similarities that are also found in the remaining tread pattern. Thus, the 16-fold overlap can be observed between all corresponding characteristic points (or minutiae) of the representation 10 of the regrooving pattern and the remaining tread pattern 2, such as, for example, the end of a groove in the remaining pattern and the end of a line in the representation 10, or an angle formed by a groove and a line in the representation 10. Advantageously, a positioning mark corresponding to a location on the tire 1 makes it easy to observe the 16-fold overlap.
[0047] The overlap 16 does not need to be precisely estimated or evaluated; it is sufficient to note its existence and that it is of a sufficient magnitude to be observed. The overlap 16 may not be homogeneous, for example, when the representation 10 of the recarving pattern is distorted relative to the sculpted residue, or vice versa.
[0048] The positioning of the representation 10 of the regrooving pattern relative to the sculpted residue is then modified, reducing the overlap 16 between the representation 10 of the regrooving pattern and the sculpted residue. Typically, the operator modifies a positioning parameter, resulting in a change in the positioning of the representation 10 of the regrooving pattern relative to the sculpted residue. This could involve moving or rotating the tire 1, or moving only the representation 10 of the regrooving pattern or the visualization of the sculpted residue. Alternatively, a display parameter affecting the display of the representation 10 of the regrooving pattern or the visualization of the sculpted residue could be modified, such as a magnification or zoom value, or a distortion.
[0049] For example, when the operator observes an overlap offset 16, the operator can interact with a human-machine interface, such as a touchscreen or button, to modify the positioning of the representation 10 of the recut pattern relative to the carving residue. Preferably, the display of the representation 10 of a recut pattern is updated during or after the positioning modification, allowing the operator to make a further positioning adjustment to reduce the overlap offset 16 even further.
[0050] Preferably, the positioning of the representation 10 of the regrooving pattern is modified until the overlap offset 16 is no longer observed, i.e., until the representation 10 of the regrooving pattern is sufficiently superimposed with the tread residue. For example, the operator interacts with the human-machine interface, observes the resulting change in the positioning of the representation 10 of the regrooving pattern via its display, and stops interacting with the human-machine interface when they consider the superposition satisfactory, for example, when the lines of the representation 10 of the regrooving pattern are superimposed on the grooves of the residue or when the regrooving pit markings appearing in the representation 10 of the regrooving pattern cover the regrooving pits of the tread 2.
[0051] Figure 4 shows an example of satisfactory superposition between the representation 10 of the re-carving pattern and the carving residue: if the superposition offset 16 is not totally zero everywhere, it can be considered that it is small enough to ensure that some grooves will re-carve the hollows of the carving residue.
[0052] It is also possible to automate the observation of the overlap 16 and / or the modification of the positioning of the representation 10 of the re-excavation pattern in relation to the sculpture residue, for example by using shape recognition algorithms.
[0053] Once the alignment is deemed satisfactory, positioning parameters are determined, such as coordinates in the XYZ coordinate system, and / or a rotation of the tire 1 typically expressed in degrees, which allows for a correspondence between the position of the tire on the grooving machine 100 and the positioning of the grooving pattern. The tire 1 is then regrooved by creating grooves at positions determined by the positioning of the representation 10 of the grooving pattern. As mentioned above, the grooving machine 100 carries a grooving blade 106 whose position relative to the tread 2 of the tire 1 is dictated by the grooving pattern.Typically, in order to present the entire tread 2 to the regrooving blade 106, the tire 1 is rotated around the rotating axle 102 which carries it, and the regrooving blade 106, for example in the shape of a U, is positioned so that its end cuts the rubber on the surface of the tread 2 following the regrooving pattern, the regrooving blade 106 can also be moved during regrooving, in particular in the transverse direction Y, in order to make a groove having a transverse component.
[0054] Once all the grooves of the regrooving pattern have been cut into the tire 1, the tire 1 can be removed from the regrooving machine, and can be mounted on a vehicle axle.
[0055] The invention is not limited to the embodiments and variants described and shown in the accompanying figures. Modifications remain possible, particularly with regard to the constitution of the various technical features or by substitution of technical equivalents, without departing from the scope of protection of the invention.
Claims
DEMANDS 1. A method for regrooving the tread of a tire (1), the tire (1) having a tread residue, the method comprising: - a display of a representation (10) of a re-grooving pattern; - a modification of the positioning of the representation (10) of the re-carving pattern relative to the sculpture residue, reducing a misalignment (16) between the representation (10) of the re-carving pattern and the sculpture residue; then - a regrooving of the tire (1) by making grooves at positions affected by the positioning of the representation (10) of the regrooving pattern.
2. Method according to claim 1, wherein the modification of the positioning of the representation (10) of the re-grooving pattern includes a displacement of the representation (10) of the re-grooving pattern and / or a deformation of the representation (10) of the re-grooving pattern.
3. Method according to claim 1 or 2, wherein the representation (10) of the re-grooving pattern is an image in which geometric elements correspond to the grooves to be cut.
4. A method according to any one of claims 1 to 3, wherein the representation (10) of the regrooving pattern is displayed on a screen simultaneously with a visualization of a tread (2) of the tire (1).
5. Method according to any one of claims 1 to 4, wherein the representation (10) of the regrooving pattern is projected onto the tread (2) of the tire (1).
6. A method according to any one of claims 1 to 5, wherein the carving residue comprises re-boring wells, the re-boring pattern comprises re-boring well markings, and the modification of the positioning of the representation (10) of the re-boring pattern comprises a reduction of an offset (16) of overlap between the re-boring wells of the carving residue, and the corresponding markings of the representation (10) of the re-boring pattern.
7. Method according to any one of claims 1 to 6, wherein the modification of the positioning of the representation (10) of the regrooving pattern includes a displacement of the tire (1).
8. Regrooving machine (100) comprising a rotating shaft (102) carrying the tire (1), a regrooving blade (106) configured to make grooves in a tread surface of the tire (1), means for displaying (108) a representation (10) of a regrooving pattern, means for modifying the positioning of the representation (10) of the regrooving pattern relative to a tread residue on the tread surface of the tire (1), and means for controlling regrooving taking into account the positioning of the representation (10) of the regrooving pattern, the regrooving machine (100) being configured to implement the method according to any one of claims 1 to 7.
9. Regrooving machine (100) according to claim 8, wherein the means for displaying (108) a representation (10) of a regrooving pattern comprise a camera configured to acquire a visualization of the tread (2) of the tire (1), and a screen configured to simultaneously display the representation (10) of the regrooving pattern with the visualization of the tread (2) of the tire (1).
10. Regrooving machine (100) according to claim 8, wherein the means for displaying (108) a representation (10) of a regrooving pattern include a projector configured to project the representation (10) of the regrooving pattern onto the tread (2) of the tire (1).