Machine and method for regrooving a tread pattern of a tyre

Abstract

The present invention relates to a machine (1) for regrooving a tread pattern of a tyre (3), comprising: - a cutting head (7) supporting two power supply terminals and a regrooving blade, the regrooving blade being capable of regrooving at least one tread pattern groove in a tread of the tyre (3) to a variable regrooving depth, the two power supply terminals being separated from one another in particular by a through-notch, and - a cooling duct (9) comprising an inlet supplied with a cooling fluid and an outlet that opens freely into the through-notch in the direction of the depth of the through-notch, capable of cooling the regrooving blade and the two power supply terminals by means of the cooling fluid. The invention also relates to a method for regrooving a tread pattern of a tyre (3) by means of such a machine (1).

Description

[0001] DESCRIPTION

[0002] Machine and method for regrooving a tire tread

[0003] technical field

[0004] The invention belongs to the field of tires, and more specifically relates to a machine for regrooving a tire tread, as well as a method for regrooving a tire tread using such a machine.

[0005] Technological background

[0006] A tire—also called a tire—has a tread pattern consisting of raised sections in the rubber, such as grooves and / or 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 recesses 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. Regrooving a tire is therefore an operation that consists of removing rubber from the existing tread to restore tread depth, following a specific pattern that may replicate the previous one or be different.This regrooving operation is usually performed manually, using a regrooving tool operated by a person, as described, for example, in patent document EP 2 031 501 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.

[0008] Such a manual grooving tool is typically powered as soon as it makes contact with the tire under the operator's pressure. Furthermore, the blade length is adjusted by the operator for each cut, ensuring the blade is always fully embedded in the tire to achieve the desired cutting depth. The blade's power supply points support the blade and act as a stop, or guide, during the grooving process. Consequently, the entire heated blade remains in constant contact with the material—either the tire rubber or the power supply points—preventing damage to the blade from overheating.

[0009] Such manual regrooving is thus 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 regrooving operation, a cutting device which includes a cutting head with a blade and a support device to press the cutting head during a regrooving operation on the tread of the tire received by the tire housing, so that a blade is in the groove of the tread.As with manual grooving, the entire heated blade remains in contact with the product, namely the tire rubber or the material of the power terminals, thus preventing any damage to the blade due to overheating. The power terminals can, however, be cooled to prevent overheating caused by thermal conduction between the blade, which is heated by the electric current flowing between these power terminals, and the power terminals themselves.

[0010] However, whether this regrooving is done manually or by such a machine, the grooving depth corresponds to the amount the blade extends beyond the contact patch on the tire. This grooving depth is dictated by the desired tread depth, which is determined by adjusting the corresponding blade extension. There is, however, a risk that the grooving will be too deep, leaving insufficient rubber thickness between the bottom of the tread and the top plies. In particular, it frequently happens that rubber wear is not uniform across the tread, and a single grooving depth setting acceptable for the majority of the tread surface may be too deep for the most worn areas.

[0011] If the thickness of the rubber protecting the crown plies is no longer sufficient, the integrity of the crown plies can no longer be guaranteed. The tire can no longer be used despite regrooving, and cannot even be retreaded. This results in a significant economic loss, since not only can the tire no longer be reused, but the regrooving operation was also unnecessary. To avoid this pitfall, one option is to regroove only lightly worn tires with even wear, which excludes many tires that could have been regrooved, or to choose a shallow regrooving depth, which reduces the lifespan of the regrooved tires.

[0012] Therefore, there is a need for a regrooving machine that can regroove a tread pattern on a tire to a variable depth, thus enabling regrooving even for a tire with pronounced and / or uneven wear, and doing so reliably.

[0013] Presentation of the invention

[0014] The invention aims to provide a regrooving machine capable of regrooving a tread pattern on a tire to a variable depth, while improving its reliability. To this end, the invention proposes a tire tread regrooving machine, the machine being notable in that it comprises:

[0015] - a cutting head supporting two power supply terminals and a regrooving blade, the two power supply terminals being suitable for supplying the regrooving blade with electrical current to heat the regrooving blade, the regrooving blade being suitable for regrooving at least one tread groove in a tire tread to a variable regrooving depth, the two power supply terminals being separated from each other, on the one hand by an electrical insulation element interposed between the two power supply terminals, and on the other hand by a through groove opening freely at a first end towards the regrooving blade, and opening freely at a second end opposite the first end, the regrooving blade protruding from the two power supply terminals, and

[0016] - a cooling duct having an inlet supplied by a cooling fluid and an outlet opening freely into the through groove in the direction of the depth of the through groove, the outlet being suitable for cooling the regrooving blade and the two supply terminals by means of the cooling fluid.

[0017] Thus, when regrooving is performed by such a machine, the heated regrooving blade used to cut the tire rubber can be partially exposed to the air without risk of overheating. The cooling fluid exiting through the outlet ensures cooling not only of the two supply terminals but also of the regrooving blade outside the regrooving zone within the tire tread. Indeed, in order to create at least one tread groove at a variable regrooving depth, at certain points the regrooving blade only partially penetrates the tread during regrooving, and a portion of the blade protruding from the tread is cooled by the cooling fluid.

[0018] Consequently, the machine's reliability is improved because the regrooving blade is protected against overheating when regrooving occurs with part of the blade exposed to the air, outside the tire. This type of cooling with a coolant is particularly advantageous when the regrooving blade is not fully immersed, i.e., is only partially inserted into the tire or its tread during the regrooving operation. Cooling with the coolant contributes significantly to the regrooving blade's durability, as it is cooled not only inside the tire by the rubber, but also externally by the coolant.In other words, the regrooving blade, protruding from the power terminals, is not always completely engaged in the tire tread, because it operates at different regrooving depths, in other words at a variable regrooving depth.

[0019] Thus, part of the regrooving blade is exposed to the air, which has a significantly lower heat transfer coefficient with the blade than the tire rubber and the power supply terminals. There is therefore a significant risk of overheating of the regrooving blade, specifically in its exposed section, which can lead to its destruction through localized melting. Furthermore, the temperature increase in this area causes an increase in the regrooving blade's resistance, which, with constant power delivered to the blade, reduces the effective power—that is, the power delivered to the regrooving blade in the tread for regrooving the tread groove.

[0020] Therefore, such a machine offers a simple solution for increasing the heat transfer coefficient between the regrooving blade and the cooling fluid. Indeed, the indirect flow of the cooling fluid, in the direction of the groove depth, keeps the feed points at a low temperature, significantly lower than that of the regrooving blade. Thus, the feed points themselves contribute to cooling the regrooving blade by thermal conduction. The indirect flow of the cooling fluid ensures both a flow of cooling fluid to the exposed portion of the regrooving blade, regardless of the regrooving depth—that is, regardless of the blade's position within the tire rubber—and the cooling of the feed points.Therefore, the cooled portion of the regrooving blade exhibits improved electrical conductivity, ensuring a consistent temperature for the part of the blade embedded in the tire tread. This facilitates regrooving and reduces the risk of blade failure. Indeed, lowering the temperature of the regrooving blade in its exposed portion, outside the tire tread, ensures optimal power transmission from the blade into the tire rubber.

[0021] The machine according to the invention is advantageously and optionally supplemented by the following features, taken individually or in any of their technically feasible combinations: - The machine includes a drive shaft designed to support and rotate the tire around its axis of rotation, such that during a retreading operation, the tire rotates around its axis of rotation and is thus mobile relative to the cutting head so that the retreading blade can recut at least one tread groove in the tire's tread. In this way, the retreading operation is carried out in a particularly simple and reliable manner.

[0022] - The drive shaft is designed to hold the tire while being coaxial with the tire's axis of rotation. Thus, with the tire fixed to the drive shaft and able to rotate around its axis of rotation, the regrooving operation is carried out in a particularly simple and reliable manner.

[0023] - The cutting head is designed to be moved, preferably radially relative to the tire's axis of rotation, to adjust the recutting depth of each tread groove recut by the recutting blade. This allows the tread groove(s) to be recut to varying depths easily.

[0024] - The machine features a movable support for the cutting head and cooling duct. This allows for easy movement of the cutting head without compromising cooling efficiency.

[0025] - The mobile support includes a supply connection linked to the inlet of the cooling duct, which supplies the inlet of the cooling duct with coolant. This makes supplying the cooling duct with coolant particularly simple.

[0026] The machine includes a control system, which is designed to operate the machine to recut at least one carving groove to a variable depth. Thus, the machine allows for automatic recutting based on predetermined data, which defines the recutting depth of the recutting blade to create the carving groove.

[0027] - The control system is specifically designed to control the rotation of the drive shaft. This allows for a particularly simple and reliable operation during the recutting process. In fact, by controlling the rotation of the drive shaft for recutting, the risk of breakage of the recutting blade is reduced.

[0028] - The control system is specifically designed to control the movement of the moving support. This allows the regrooving depth of the regrooving blade to be controlled automatically, in a particularly simple and reliable manner. - The control system is also specifically designed to control the machine to regroove at least one tread groove to a variable depth. This makes it possible to regroove a complete tread profile of the tire, conforming to a predetermined profile.

[0029] - The outlet of the cooling duct is closer to the first end than to the second end, preferably between 2 and 5 times closer to the first end than to the second end. This ensures optimal cooling, as the coolant with the lowest outlet temperature is ejected near the recutting blade, while simultaneously cooling the power terminals with optimal cooling near the recutting blade.

[0030] - The through groove extends longitudinally radially and orthogonally to the axis of rotation of the tire. Thus, the deflection of the cooling fluid flow at the outlet of the cooling channel is omnidirectional, which leads to an equal distribution between a cooling fluid flow directed towards the first end in the direction of the regrooving blade and a cooling fluid flow directed towards the second end, regardless of the regrooving depth.

[0031] - The through groove is wider at the second end than at the first end, preferably between 1.5 and 3 times wider at the second end than at the first end, and more preferably twice as wide at the second end as at the first end. This optimizes the flow of the cooling fluid.

[0032] - The through groove widens regularly from the first end to the second end. This optimizes the flow of cooling fluid.

[0033] - The coolant is gaseous, preferably air, and more preferably compressed air. This eliminates the need for further tire cleaning and provides enhanced cooling due to the expansion of the gaseous coolant as it exits the cooling line.

[0034] - The recutting blade has two branches connected by a central portion, the two branches extending away from each other towards the first end, each branch being fixed to a respective power supply terminal. Thus, the recutting blade is made in a simple manner.

[0035] - The through groove has two edges, preferably both edges being parallel to a respective branch of the recutting blade. - The recutting blade is obtained by folding a flat strip, preferably by a single fold of a flat strip. Thus, the recutting blade is obtained in a particularly simple and inexpensive manner.

[0036] - The recutting blade is metallic, preferably made of steel. This makes it particularly easy to heat the recutting blade locally, in the area effective for recutting, and to cool it locally, in the area exposed to the air.

[0037] - The recutting blade has a U or V cross-section. Thus, the recutting blade has a particularly simple shape while being robust.

[0038] - Each branch is flat.

[0039] - The central portion forms a bend or a curve, preferably in a C shape.

[0040] - The outlet is designed to eject cooling fluid towards the bottom of the through groove. This ensures good distribution of the cooling fluid, due to the deflection of the cooling fluid by the bottom of the through groove.

[0041] - The outlet is designed to cool the two feed terminals and the re-grooving blade using the cooling fluid during a re-grooving operation. Indeed, the cooling fluid ejected from the outlet is indirectly directed towards the elements to be cooled, namely the two feed terminals and the re-grooving blade.

[0042] The two power supply terminals are designed to supply the recutting blade with electric current to cause resistive heating of the recutting blade; in other words, to heat the recutting blade by Joule heating. This allows the recutting blade to be heated in a particularly simple and reliable manner.

[0043] The invention also proposes a method for regrooving a tire tread using a machine as previously described, which comprises the following steps:

[0044] - supply the recutting blade with electrical current via the two power supply terminals to heat the recutting blade, and cool the recutting blade and the two power supply terminals using the cooling fluid exiting through the outlet,

[0045] - regroove the tire tread to a variable regrooving depth by creating at least one tread groove.

[0046] The method according to the invention is advantageously and optionally complemented by the following various steps taken alone or according to any of their various technically possible combinations: - Maintain the pneumatic on the drive shaft coaxially to the drive shaft 5.

[0047] - The step of regrooving the tire tread to a variable regrooving depth by creating at least one tread groove includes the following sub-step: controlling the movement of the cutting head to adjust the regrooving depth of a tread groove.

[0048] - The step of regrooving the tire tread to a variable regrooving depth by creating at least one tread groove includes the following sub-step: rotating the drive shaft so as to rotate the tire around the axis of rotation of the tire.

[0049] Presentation of the figures

[0050] 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:

[0051] - Figure 1 schematically represents a re-grooving machine according to one embodiment;

[0052] - Figure 2 schematically and in perspective represents a detail of the machine shown in Figure 1;

[0053] - Figure 3 schematically represents, in cross-section, a detail of the machine shown in Figure 1;

[0054] - Figure 4 schematically represents in section AA a detail of the machine shown in Figure 3, during a tire regrooving operation;

[0055] - Figure 5 schematically represents the steps of a tire regrooving process according to one embodiment.

[0056] Throughout the figures, similar elements are designated by identical references.

[0057] Detailed description

[0058] In the accompanying figures, the various geometric orientations are defined in an XYZ coordinate system, defined by a longitudinal or circumferential direction X, parallel to a 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.

[0059] Figure 1 schematically represents a regrooving machine 1. Machine 1 is a regrooving machine for the tread of a tire 3.

[0060] Advantageously, the machine 1 includes a drive shaft 5 suitable for supporting and driving the tire 3 in rotation around the axis of rotation of the tire, so that during a regrooving operation, the tire 3 rotates around its axis of rotation.

[0061] Preferably, the drive shaft 5 is designed to hold the tire 3 while being coaxial with the axis of rotation of the tire 3.

[0062] Machine 1 includes a cutting head 7 and a cooling duct 9.

[0063] Preferably, machine 1 includes a movable support 11.

[0064] Advantageously, the mobile support 11 is mobile relative to a fixed frame 13 of the machine 1, preferably is mobile only parallel to the radial plane.

[0065] Preferably, the mobile support 11 supports the cutting head 7 and the cooling duct 9.

[0066] Advantageously, machine 1 includes a control system 14.

[0067] Figure 2 schematically and in perspective represents a detail of machine 1.

[0068] As shown in Figure 2, the cutting head 7 supports two power supply terminals 15a, 15b and a regrooving blade 17. In order to allow good visualization of various elements shown below, the cooling duct 9 is not visible in Figure 2.

[0069] The two power supply terminals 15a, 15b are suitable for supplying the regrooving blade 17 with electric current to heat the regrooving blade 17.

[0070] More specifically, the two power supply terminals 15a, 15b are suitable for supplying the re-grooving blade 17 with electric current to cause resistive heating of the re-grooving blade 17, in other words to cause heating of the re-grooving blade 17 by Joule effect.

[0071] The regrooving blade 17 protrudes from the two power supply terminals 15a, 15b. The two power supply terminals 15a, 15b are separated from each other. More precisely, the two power supply terminals 15a, 15b are separated from each other, on the one hand by an electrical insulation element 19 interposed between the two power supply terminals 15a, 15b, and on the other hand, by a through groove 21.

[0072] Advantageously, the electrical insulation element 19 is also thermally insulating, in that it has a lower heat transfer coefficient than each of the supply terminals 15a, 15b. Preferably, the electrical insulation element 19 is made of bakelite.

[0073] The through groove 21 opens freely at a first end El towards the recutting blade 17, and also opens freely at a second end E2 opposite the first end EL

[0074] Advantageously, the through groove 21 extends longitudinally radially with respect to the axis of rotation of the tire 3. Preferably, the through groove 21 extends longitudinally orthogonally to the axis of rotation of the tire 3. Thus, the through groove 21 extends longitudinally in the radial direction Z, from its first end El to its second end E2.

[0075] Advantageously, the through groove 21 is wider at the second end E2 than at the first end EL. Preferably, the through groove 21 is between 1.5 times and 3 times wider at the second end E2 than at the first end EL. More preferably, the through groove 21 is twice as wide at the second end as at the first end, optionally to within 10%.

[0076] Preferably, the through groove 21 has two edges. Preferably, these edges are opposite each other. By edges of the through groove 21, we mean the lateral walls of the through groove 21, which extend towards the bottom of the through groove 21, and are thus adjacent to the bottom of the through groove 21.

[0077] Advantageously, the through groove 21 widens regularly from the first end El to the second end E2. In other words, the edges of the through groove 21 are preferably planar, and optionally symmetrical with respect to each other.

[0078] Advantageously, the re-grooving blade 17 has two branches 17a, 17b connected by a central portion 17c. The two branches 17a, 17b move away from each other towards the first end EL. Each of the two branches 17a, 17b is fixed to a respective power supply terminal 15a, 15b.

[0079] Preferably, each branch 17a, 17b is flat. Advantageously, the edges of the through groove 21 are each parallel to a respective branch 17a, 17b of the recutting blade 17.

[0080] Preferably, the central portion 17c forms a bend or a curve, preferably in a C shape.

[0081] Advantageously, the regrooving blade 17 is obtained by folding a flat strip, preferably by a single fold of a flat strip.

[0082] Preferably, the re-grooving blade 17 is beveled on at least one longitudinal edge, in order to facilitate re-grooving.

[0083] Advantageously, the re-grooving blade 17 is metallic, preferably made of steel.

[0084] Preferably, the recutting blade 17 has a U or V cross-section. By cross-section, we must understand here a section parallel to the radial plane.

[0085] Figure 3 schematically represents in cross-section a detail of machine 1, more specifically the cutting head 7 and the cooling duct 9, as well as a portion of the moving support 11.

[0086] As shown in Figure 3, the cooling channel 9 has an inlet 9a supplied by a cooling fluid and an outlet 9b opening freely into the through groove 21 in the direction of the depth of the through groove 21. The outlet 9b is suitable for cooling the regrooving blade 17 and the two supply terminals 15a, 15b by means of the cooling fluid.

[0087] Advantageously, the coolant is a gas. Preferably, the coolant is air. More preferably, the coolant is compressed air. If applicable, at inlet 9a, the compressed air is advantageously compressed to between 2 and 15 bar, preferably between 4 and 8 bar, more preferably between 6 and 7 bar, each of these values ​​being optionally within 10% or 20%.

[0088] Preferably, the cooling duct 9 is bent, so that only the outlet 9b is present within the through groove 21. Thus, the flow of cooling fluid exiting through outlet 9b is not affected by the presence of the cooling duct, and the cooling is optimal.

[0089] Figure 4 schematically represents in section AA a detail of machine 1 shown in figure 3, during a regrooving operation of a tire 3.

[0090] As can easily be seen in Figure 4, on which only the ends of the cooling duct 9 are shown, the outlet 9b of the cooling duct 9 is closer to the first end El than to the second end E2 of the through groove 21. Preferably, the outlet 9b of the cooling duct 9 is between 2 and 5 times closer to the first end El than to the second end E2.

[0091] Advantageously, outlet 9b is suitable for ejecting cooling fluid towards the bottom of the through groove 21, preferably towards the electrical insulation element 19.

[0092] Advantageously, outlet 9b is suitable for cooling the two supply terminals 15a, 15b and the re-grooving blade 17 by means of the cooling fluid during a re-grooving operation.

[0093] Preferably, the movable support 11 includes a supply connection 22 connected to the inlet 9a of the cooling duct 9, which supplies the inlet 9a of the cooling duct 9 with cooling fluid. For example, the inlet 9a terminates in a flange 25 forming a sealing cover. Advantageously, the flange 25 is fixed to the movable support 11, preferably by screws 27. The flange 25 is thus provided with a through hole allowing the passage of cooling fluid into the cooling duct 9 from a supply connection 28 of the movable support 11. For example, the supply connection 28 is formed by a bore. To achieve a seal, a peripheral gasket 25a can be housed in a peripheral groove of the flange 25, which is compressed against the supply connection 28.In other words, the mobile support 11 has a supply fitting 28 connected to the inlet 9a of the cooling duct 9, which supplies cooling fluid to the inlet 9a of the cooling duct 9.

[0094] As shown in Figure 4, the regrooving blade 17 is suitable for regrooving at least one tread groove 29 in a tread 31 of a tire 3 to a variable regrooving depth.

[0095] Advantageously, the tire 3 rotates around its axis of rotation and is thus mobile relative to the cutting head 7 so that the regrooving blade 17 regrooves at least one tread groove 29 in the tread 31 of the tire 3.

[0096] Preferably, the cutting head 7 is designed to be moved, preferably radially with respect to the axis of rotation of the tire 3, in order to adjust the depth of recutting of each groove 29 recut by the recutting blade 17.

[0097] If the regrooving blade 17 is held fixed, the tread groove 29 is circumferential around the tire 3, as shown in Figure 4. The regrooving blade 17 can also be moved during the regrooving operation, particularly in the transverse direction Y, to create a tread groove 29 with a transverse component. To switch from one tread groove 29 to another, the regrooving blade 17 is simply raised in the radial direction Z, and then the relative position between the tire 3 and the regrooving blade 17 is changed, for example, by transverse translation of the cutter head 7 carrying the regrooving blade 17 or of the movable support 11, by rotation of the regrooving blade 17, and / or by rotation of the tire 3, to create a new tread groove 29 on the tread 31 of the tire 3.

[0098] Advantageously, the control system 14 is suitable for operating the machine 1 to recut at least one carving groove 29 to a variable recutting depth. In other words, the control system 14 is suitable for operating the machine 1 to recut at least one carving groove 29 to a variable recutting depth.

[0099] Preferably, the control system 14 is designed to control the rotation of the drive shaft 5.

[0100] Preferably, the control system 14 is designed to control the movement of the mobile support 11.

[0101] Figure 5 represents the main steps of a process for regrooving a tread pattern of a tire 3 using a machine 1 as previously described.

[0102] Such a re-excavation process includes the following steps:

[0103] - P20 supply the regrooving blade 17 with electrical current via the two power supply terminals 15a, 15b to heat the regrooving blade 17, and simultaneously cool the regrooving blade 17 and the two power supply terminals 15a, 15b by means of the cooling fluid exiting through outlet 9b,

[0104] - P30 regroove the tread 31 of the tire 3 to a variable regrooving depth by making at least one tread groove 29.

[0105] Preferably, the re-excavation process also includes the following step:

[0106] - P10 maintain the pneumatic 3 on the drive shaft 5 coaxially to the drive shaft 5.

[0107] Advantageously, step P30 of regrooving the tread 31 of the tire 3 to a variable regrooving depth by creating at least one tread groove 29 comprises the following substep:

[0108] - P31 control the movement of the cutting head 7 to adjust the depth of re-grooving a carving groove 29.

[0109] Preferably, step P30 of regrooving the tread 31 of the tire 3 to a variable regrooving depth by making at least one tread groove 29 includes the following substep: - P32 rotate the drive shaft 5 so as to rotate the tire 3 around the axis of rotation of the tire 3.

[0110] Once all the tread grooves 29 have been recut in the tire 3, the tire 3 can be removed from the recutting machine 1, and can be mounted on a vehicle axle for use.

[0111] 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. Machine (1) for regrooving the tread of a tire (3), the machine (1) being characterized in that it comprises: - a cutting head (7) supporting two power supply terminals (15a, 15b) and a regrooving blade (17), the two power supply terminals (15a, 15b) being adapted to supply the regrooving blade (17) with electric current to heat the regrooving blade (17), the regrooving blade (17) being adapted to regroove at least one tread groove (29) in a tread (31) of the tire (3) to a variable regrooving depth, the two power supply terminals (15a, 15b) being separated from each other, on the one hand by an electrical insulation element (19) interposed between the two power supply terminals (15a, 15b), and on the other hand by a through groove (21) opening freely at a first end (11) towards the regrooving blade (17), and opening freely at a second end (E2) opposite the first end (El), the regrooving blade (17) protruding from the two power supply terminals (15a, 15b), and - a cooling conduit (9) having an inlet (9a) supplied by a cooling fluid and an outlet (9b) opening freely into the through groove (21) in the direction of the depth of the through groove (21), the outlet (9b) being suitable for cooling by means of the cooling fluid the regrooving blade (17) and the two supply terminals (15a, 15b).

2. Machine (1) according to claim 1, wherein the outlet (9b) of the cooling duct (9) is closer to the first end (El) than to the second end (E2), preferably between 2 and 5 times closer to the first end (El) than to the second end (E2).

3. Machine (1) according to claim 1 or 2, wherein the through groove (21) has two edges, the two edges each being parallel to a respective branch (17a, 17b) of the regrooving blade (17).

4. Machine (1) according to any one of claims 1 to 3, wherein the through groove (21) widens regularly from the first end (E1) to the second end (E2).

5. Machine (1) according to any one of claims 1 to 4, wherein the electrical insulation element (19) forms at least a part of the bottom of the through groove (21).

6. Machine (1) according to any one of claims 1 to 5, wherein the cooling fluid is gaseous, preferably air.

7. Machine (1) according to any one of claims 1 to 6, which includes a drive shaft (5) adapted to support and drive the tire (3) in rotation around the axis of rotation of the tire (3), such that during a regrooving operation, the tire (3) rotates around its axis of rotation and is thus mobile relative to the cutting head (7) so that the regrooving blade (17) regrooves at least one tread groove (29) in the tread (31) of the tire (3).

8. Machine (1) according to any one of claims 1 to 7, wherein the cutting head (7) is adapted to be moved, preferably radially with respect to the axis of rotation of the pneumatic (3), in order to adjust the depth of regrooving of each carving groove (29) regrooved by the regrooving blade (17).

9. Machine (1) according to any one of claims 1 to 8, which includes a movable support (11) supporting the cutting head (7) and the cooling duct (9).

10. A method for regrooving the tread pattern of a tire (3) using a machine (1) according to any one of claims 1 to 9, which comprises the following steps: - P20 supply the regrooving blade (17) with electrical current through the two power supply terminals (15a, 15b) to heat the regrooving blade (17), and cool the regrooving blade (17) and the two power supply terminals (15a, 15b) by means of the cooling fluid exiting through the outlet (9b), - P30 regroove the tread (31) of the tire (3) to a variable regrooving depth by making at least one tread groove (29).

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