Double-blade machining facility and method for recovering rubber from tyres

Abstract

The present invention relates to a machining method that aims to recover the constituent material of the outer layer (4) of a tyre (1) that has a wall (3) comprising, on the one hand, at least one outer layer (4) made of elastomer that is shaped to have tread pattern blocks (60) separated by grooves (61) and, on the other hand, at least one reinforcing ply (5) located beneath the outer layer (4) and containing a plurality of reinforcing wires (6), the tyre (1), during which machining method, is rotated (R20) about itself around the main axis (Z20) in a chosen direction of rotation (R20+, R20-), and a first cutting tool (2) and a second cutting tool (2'), during which machining method, are simultaneously engaged, preferably one in each hemisphere (H1, H2) of the tyre, in order to remove material from one or more regions of the outer layer (4) to a depth located between the bottom (61B) of the grooves (61) and the reinforcing ply (5).

Description

Installation and method for a double-knife machining process for the recovery of rubber from bandages

[0001] The present invention relates to the field of bandage recycling, in particular pneumatic bandages.

[0002] More specifically, the invention aims to recover, particularly from a tire which has definitively reached the end of its life and whose casing can therefore no longer be repaired or reused, the largest possible quantity of the rubber-based material which constitutes the outer layer covering the casing, and in particular the largest possible quantity of the material constituting the tread.

[0003] To reconcile the imperatives of industrial efficiency and respect for the environment, however, we want to have a process and an installation that allows us to quickly and easily collect a significant part of the potentially recoverable material on each bandage, while incurring the lowest possible energy expenditure.

[0004] The objects assigned to the invention therefore aim to provide an installation and a machining process which allows for the efficient removal of a maximum amount of rubber-based material from bandages while remaining energy-efficient.

[0005] The objects assigned to the invention are achieved by means of a process for machining a bandage, said bandage having a wall which comprises, on the one hand, at least one outer layer based on elastomer, which has been shaped to present blocks of sculpture separated by grooves, and on the other hand, at least one reinforcing layer which is located under said outer layer and which contains a plurality of reinforcing threads, said process comprising a material removal step during which: - by means of a rotating support having an axis of rotation called the "main axis", the tire is rotated on itself, around said main axis, in a chosen direction of rotation, and - while the bandage is rotating in the chosen direction, at least two cutting tools are used simultaneously, acting against the outer layer to remove material, namely at least one first cutting tool which is carried by a first positioning system allowing the positioning and movement of said first cutting tool relative to the main axis, so as to make the first cutting tool follow a first cutting path, and at least a second cutting tool which is carried by a second positioning system allowing the positioning and movement of said second cutting tool relative to the main axis, so as to make the second cutting tool follow a second cutting path distinct from the first cutting path, said first and second cutting paths being defined so that they allow material to be removed, in one or more areas of the outer layer, to a depth which is located between the bottom of the grooves and the reinforcing layer.

[0006] Advantageously, the multiplication of cutting tools, and the fact that the cutting tools intervene simultaneously, in a time at least partially masked or even totally masked from each other, makes it possible to machine the band quickly, removing material from the outer layer simultaneously in several working areas, which reduces the cycle time.

[0007] Furthermore, because the cutting tools are arranged so that they can all operate in the same direction of rotation of the band, the entire material removal process is carried out without needing to stop the band's rotation or reverse its direction. This minimizes the number and duration of transient acceleration and braking phases of the support and the band, and therefore reduces the corresponding time and energy losses, particularly those related to inertial phenomena.

[0008] Finally, the independence of the positioning systems advantageously allows the trajectory of each cutting tool to be adapted to the area of ​​the bandage covered by said cutting tool, and in particular to differentiate the second cutting trajectory from the first cutting trajectory according to the reinforcement wire layout specific to each bandage. Thus, when each of the first and second cutting tools is assigned to machining a hemisphere of the bandage distinct from the hemisphere assigned to the other cutting tool, each cutting tool can be brought as close as possible to the reinforcement layer within the hemisphere of the bandage covered by said cutting tool, taking into account the direction of the bandage and the orientation of the reinforcement wires in the hemisphere concerned, without risking snagging or tearing the reinforcement wires, and therefore without risking... block the operation of the installation or damage one or both of the cutting tools.

[0009] Other objects, features and advantages of the invention will become apparent in more detail from the following description, as well as from the accompanying drawings, which are provided for illustrative purposes only and are not intended to be limiting, including:

[0010] Figure 1 illustrates, in perspective view, an example of an installation for implementing a process according to the invention, here more particularly an installation comprising two robotic arms carrying respectively a first cutting tool and a second cutting tool which are here arranged on either side of the rotating support which carries the band to be machined.

[0011] Figure 2 is a front view of the installation in Figure 1, in a plane normal to the main axis.

[0012] Figure 3 illustrates, according to a schematic cutaway perspective view, a bandage that can be treated by the process according to the invention, said bandage having a first arrangement scheme of its reinforcing wires, comprising in this case a first reinforcement layer, radially the outermost, which has a first set of reinforcing wires arranged parallel to each other, according to a first oblique orientation with respect to the circumferential equatorial direction of the bandage, and a second reinforcement layer, radially more internal than the first reinforcement layer, which is partially covered by the first reinforcement layer and which extends axially beyond the axial limits of the first reinforcement layer, and which comprises a second set of reinforcing wires, arranged parallel to each other, and having a second oblique orientation of the same sign as the first orientation of the reinforcing wires of the first reinforcement layer.

[0013] Figure 4 is a cross-sectional view, in a radial plane containing the main axis, and before any material removal operation, of a bandage that can be treated by the process according to the invention, preferably a bandage that has a first implantation scheme according to Figure 3.

[0014] Figures 5A and 5B illustrate, in schematic perspective and radial cross-section views respectively, the banding of Figures 3 and 4 during a preliminary trenching stage, in which a trench is dug circumferential in the equatorial zone of the bandage using the first cutting tool, before proceeding to the material removal step which involves simultaneously the first cutting tool and the second cutting tool.

[0015] Figures 6A, 6B, and 6C illustrate, respectively in a schematic partial top view, a perspective view, and a schematic radial cross-section, the principle of implementing the first cutting path of the first cutting tool within the bandage shown in Figures 3, 4, 5A, and 5B. This path allows the removal of the outer layer present in the first hemisphere of the bandage by axially moving the first cutting tool, flush with the first reinforcement layer, from the equatorial trench towards a first axial end of the bandage, over a first axial cutting area that covers one hemisphere of the bandage. For clarity, the second cutting tool and the second cutting path are not shown in these figures.

[0016] Figures 7A and 7B illustrate, respectively in a schematic partial top view and a schematic cross-sectional view in a radial plane, the bandage of Figures 3, 4, 5A and 5B, during the simultaneous use of the first and second cutting tools. While the bandage is rotating in the same direction, the first cutting tool executes the first cutting path detailed in Figures 6A, 6B, 6C to remove the outer layer in the first hemisphere, here by sliding in contact with the reinforcing wires, while the second cutting tool simultaneously executes the second cutting path to remove the outer layer in the second hemisphere of the bandage, moving axially towards the second axial end of the bandage, but with a centrifugal radial offset of the second cutting path relative to the first cutting path, which allows the second cutting tool to be maintained.at least in a part of the second hemisphere, at a radial distance from the main Taxe which is strictly greater than that used for the first cutting tool in the first hemisphere of the bandage, in order to retain in at least part or even all of the second hemisphere, for safety, a residual thickness of outer layer which protects the reinforcing threads of the second hemisphere from tearing, in particular at the corresponding edges of the reinforcing layers.

[0017] Figure 8 illustrates, in a cutaway perspective view including an enlarged inset section, another type of bandage that can be treated by the process according to The invention. This tire features a second arrangement, which in this case comprises a first radially external reinforcing layer having a first set of reinforcing threads arranged parallel to each other and substantially, or even exactly, parallel to the equatorial circumferential direction of the tire. This first reinforcing layer, also called the "band," thus forms a ring that preferably covers the entire axial width of the top of the tire. Such a first reinforcing layer can be obtained, in particular, by winding around the main axis, in several consecutive contiguous turns, a continuous strip formed of a matrix, for example, a rubber matrix, in which parallel and continuous reinforcing threads are embedded.This second arrangement scheme further provides for a second reinforcement layer, which is located under the first reinforcement layer and which includes a second set of reinforcing wires, preferably arranged obliquely with respect to the equatorial circumferential direction, and whose axial ends are located in retreat from the corresponding axial ends of the first reinforcement layer, so that the first reinforcement layer extends axially beyond the second reinforcement layer and completely covers said second reinforcement layer.

[0018] Figure 9 is a cross-sectional view, in a radial plane containing the main axis, and before any material removal operation, of a bandage which has a second implantation scheme according to Figure 8.

[0019] Figures 10A and 10B illustrate, respectively in a schematic partial top view and a schematic cross-sectional view in a radial plane, the bandage of Figure 9 during a preliminary trenching stage, during which a circumferential trench is dug in the equatorial zone of the bandage using the first cutting tool, before proceeding to the material removal stage which involves simultaneously the first cutting tool and the second cutting tool.

[0020] Figures 11A and 11B illustrate, respectively in a schematic partial top view and a schematic cross-sectional view in a radial plane, the bandage of Figures 9 and 10A and 10B during a material removal step according to the invention, in which the outer layer in the first hemisphere of the bandage is removed by means of a first cutting tool which is advanced axially in contact with the first reinforcing layer, from the equatorial trench to the first axial end of the bandage, and the outer layer in the second hemisphere of the bandage by means of a second cutting tool which is advanced axially in contact with the first reinforcement layer, from the equatorial trench to the second axial end of the bandage.

[0021] Figure 12 illustrates, in a detailed perspective view, the end of a robotic arm of the installation of Figures 1 and 2 which carries a cutting tool formed by a rotating cylindrical knife as well as the sharpening system for maintaining the circular edge of said knife.

[0022] Figure 13 illustrates, in a schematic radial view, the principle of a material removal step, applicable in particular to a tire with the first layout mentioned above. During this step, a first cutting path and a second cutting path are executed, allowing the first and second cutting tools to be moved axially at a radial distance from the main axis. This radial distance is precisely the distance between the bottom of the grooves and the outermost radial surface of the reinforcing layer. Such cutting paths can be defined based on knowledge of the radial position of the bottom of one or more grooves and can, depending on the case, either follow the curvature of the tire, which corresponds to the imaginary line passing through the bottoms of the grooves, or be straight and parallel to the main axis.

[0023] Figure 14 illustrates, in a schematic view in a radial plane, the principle by which, to ensure that the cutting tool comes into contact with the reinforcing layer and then slides along the layer while remaining in contact with the reinforcing wires, in order to remove as much thickness as possible from the outer layer, the cutting tool is brought to a starting position, here in the equatorial plane, which is radially closer to the principal axis by a value called the "nominal deflection value," than the reinforcing layer, whose outermost face, in the absence of a cutting tool, is located at a radial distance from the principal axis called the "radial envelope distance." Thus, the cutting tool is advantageously pre-stressed against the reinforcing layer by locally creating a slight centripetal radial deformation of the reinforcing wires through elastic bending.

[0024] The present invention relates to a method for machining a tire 1.

[0025] The machining process according to the invention can be used for example for the stripping of a tire 1, that is to say for removing from the tire the remains of a used tread, with a view to retreading said tire, when the carcass of said tire 1 is reusable.

[0026] However, preferably, the machining process according to the invention will be part of a process for recycling a rubber-based material present on the tire 1, preferably a process for recycling the rubber-based material constituting the tread, and will therefore aim to recover the largest possible quantity of said material relative to the total quantity of said material that is present on said tire 1.

[0027] Such a recycling process will be particularly applicable to end-of-life bandages, whose casing can no longer be repaired or reused, and which must therefore be dismantled to recover the raw materials.

[0028] As can be seen in particular in Figures 4, 9, 13 and 14, bandage 1 has a wall 3 which includes on the one hand at least one outer layer 4 based on elastomer, which has been shaped to present blocks of sculpture 60 separated by grooves 61, and on the other hand at least one reinforcing layer 5 which is located under said outer layer 4 and which contains a plurality of reinforcing threads 6.

[0029] Of course, since the sculpture blocks 60 and the grooves 61 are initially shaped on the new or freshly retreaded tire 1, the process according to the invention can be applied indifferently to worn tires 1, on which there will remain remains of sculpture blocks 60 and grooves 61 which will depend on the degree of wear of the tire 1, or to new or almost new tires, discarded for quality reasons, and presenting intact sculpture blocks 60 and grooves 61.

[0030] Preferably, the grooves 61 taken into consideration for the purposes of the invention are circumferential grooves, which form the deepest hollows on the surface of the wall 3.

[0031] We will denote E4 the thickness of the outer layer 4, and in particular the residual thickness of said outer layer, which separates the outer surface of the wall 3 from the surface of the reinforcement layer 5, 5' closest to said outer surface of the wall 3.

[0032] As is known, the reinforcing layer 5, 5' is preferably formed by a thin layer of a matrix-forming material extending in two principal directions which define the surface of the reinforcing layer, and in the thickness of which the reinforcing wires 6, 6' are embedded.

[0033] In particular, we may have a reinforcement layer 5, 5' whose matrix is ​​formed on the basis of elastomer, preferably on the basis of rubber, and containing reinforcing wires 6 metallic, or possibly in polymer such as aramid.

[0034] Alternatively, the reinforcement layer 5, 5' may have a resin matrix reinforced by fiberglass reinforcing threads 6, 6'.

[0035] Within the same reinforcement layer 5, 5', the reinforcement wires 6, 6' will preferably be arranged side by side, parallel to each other, although other arrangements are conceivable without going out of the scope of the invention.

[0036] The said reinforcing wires 6, 6' are arranged according to an implantation scheme, which is specific to bandage 1.

[0037] The layout diagram defines the path of the reinforcing wires 6, 6' within the reinforcing layer 5, 5', and therefore in particular the orientation A6, A6' of said reinforcing wires 6, 6', or the spacing between neighboring reinforcing wires 6, 6'.

[0038] As an example, we may consider a first arrangement scheme, as illustrated in Figures 3, 4, and 7A, which in this case comprises a first reinforcement layer 5, radially the outermost, which has a first set of reinforcing wires 6, called the "first reinforcing wires 6," arranged parallel to each other, according to a first orientation A6 oblique to the equatorial circumferential direction of the bandage 1, and a second reinforcement layer 5', radially more internal than the first reinforcement layer 5, which is partially covered by the first reinforcement layer 5 and which extends axially beyond the axial limits, or "edges" 51, 52, of the first reinforcement layer 5, and which comprises a second set of reinforcing wires 6', called the "second reinforcing wires 6'," arranged parallel to each other, and having a second oblique orientation A6', forming here an angle Aô' ang on figure 6A,second orientation A6' which has the same sign as the first orientation A6 of the reinforcing wires 6 of the first reinforcing layer 5.,

[0039] Such an initial layout scheme may be frequently found within a tire 1 intended for heavy goods vehicles.

[0040] The first reinforcing wires 6 of the first reinforcing layer 5, installed according to this first layout, will preferably be metallic. Similarly, the second reinforcing wires 6' of the second reinforcing layer 5', installed according to this first layout, will preferably be metallic.

[0041] According to another example, a second reinforcement scheme, as illustrated in Figures 8 and 9, can be considered. This scheme comprises a first radially external reinforcing layer 5, which has a first set of reinforcing threads 6 arranged parallel to each other and substantially, or even exactly, parallel to the equatorial circumferential direction of the tire. This first reinforcing layer, also called the "band," thus forms a ring that preferably covers the entire axial width of the tire's apex. Such a first reinforcing layer 5 can be obtained, in particular, by winding a continuous band of rubber matrix, in which parallel and continuous reinforcing threads 6 are embedded, onto several consecutive, contiguous turns around the central axis of the tire.This second arrangement scheme further provides for a second reinforcing layer 5', which is located under the first reinforcing layer 5 and which includes a second set of reinforcing wires 6', preferably arranged obliquely with respect to the equatorial circumferential direction, and whose axial ends are located in retreat from the corresponding axial ends of the first reinforcing layer 5, so that the first reinforcing layer 5 extends axially beyond the second reinforcing layer 5' and completely covers said second reinforcing layer 5'.

[0042] The first reinforcing wires 6 used in the first reinforcing layer 5 according to this second implantation scheme, radially the outermost, may be made of a metallic material, for example steel, of a composite material comprising glass fibers embedded in a resin, or even of a polymer textile material such as polyamide (“Nylon”) or aramid.

[0043] The second installation scheme described above can be implemented in particular, but not exclusively, within tires intended to equip passenger vehicles.

[0044] For ease of description, when it is not necessary to specifically distinguish between the first reinforcing layer 5 and the second reinforcing layer 5', respectively between the first reinforcing wires 6 and the second reinforcing wires 6', and in particular where characteristics can apply indifferently to a bandage 1 in which a single reinforcement layer would be concerned by the machining operation or to a bandage in which several reinforcement layers would be concerned by the machining operation, one can refer generically to a "reinforcement layer 5, 5'" or to a "reinforcement layer 5", and respectively to "reinforcement wires 6, 6'" or "reinforcement wires 6".

[0045] Furthermore, it should be noted that the invention is applicable to a wide variety of tire types, including toroidal tires for vehicle wheels, such as pneumatic tires or airless tires suspended by flexible spokes, as well as tires forming tracks for construction equipment, agricultural machinery, or snowmobiles, and even tires forming reinforced belts such as transmission belts or conveyor belts. The support 20, intended to receive the tire 1 for machining operations, can of course be adapted according to the type of tire 1 being processed.

[0046] Preferably, the process can be applied to tires 1 intended for heavy goods vehicles, typically vehicles whose total authorized weight exceeds 3.5 tonnes, said tires being sized to be mounted on rims with dimensions between 16.5 inches and 24 inches.

[0047] The process can also be applied to tires 1 intended for passenger vehicles, and therefore adapted to rims with a diameter between 13 inches and 24 inches.

[0048] The method according to the invention can of course be applied without restriction to tires of very varied dimensions, including very large tires, for example civil engineering tires intended to be mounted on rims up to 63 inches.

[0049] Preferably, in a manner known per se, and as can be seen in particular in figures 1, 2, 4, 9, 13 and 14, the bandage 1 has a first annular heel 7 and a second annular heel 8, provided respectively with a first and a second rod (not shown), and the wall 3 of the bandage forms a radially external apex 10, thus that a first flank 11 which connects said summit 10 to the first heel 7 and a second flank 12 which connects the summit 10 to the second heel 8.

[0050] As is known in itself, the first and second heels 7, 8 allow the mounting of the tire onto a rim.

[0051] The outer layer 4 will preferentially correspond to the tread of the tire 1, which extends over the top 10 of said tire 1.

[0052] Preferably, the wall 3 of the bandage has a toroidal shape of revolution, bulging outwards, and may more preferably delimit in this way, in the case where the bandage 1 is a pneumatic bandage, a cavity which allows to contain the inflation gas of said pneumatic bandage.

[0053] According to the invention, the process comprises a material removal step during which: - by means of a rotating support 20 having a rotation axis called the "main axis" Z20, the tire 1 is driven in rotation R20 on itself, around said main axis Z20, in a chosen direction of rotation R20+, R20-, and - while the bandage 1 is in rotation R20 in the chosen direction of rotation R20+, R20-, at least two cutting tools 2, 2' are used which act simultaneously against the outer layer 4 to remove material from it, namely at least a first cutting tool 2 which is carried by a first positioning system 42 allowing the positioning and movement of said first cutting tool 2 relative to the main axis Z20, so as to make the first cutting tool 2 follow a first cutting path T2_l, and at least a second cutting tool 2' which is carried by a second positioning system 42' allowing the positioning and movement of said second cutting tool 2' relative to the main axis Z20, so as to make the second cutting tool 2' follow a second cutting path T2_2 distinct from the first cutting path T2_l, said first and second cutting paths T2_l,T2_2 being defined so that they allow material to be removed, in one or more areas of the outer layer 4, to a depth which is located between the bottom 61B of the grooves 61 and the reinforcing layer 5.

[0054] Advantageously, the process according to the invention makes it possible to remove material from the outer layer 4 to a significant depth, close to the reinforcing layer 5, 5' or even which coincides with the implantation depth of the reinforcing layer 5, 5', thus maximizing the amount of material recovered, while avoiding tearing the reinforcing threads 6, 6'. It is therefore advantageous to selectively recover a maximum of recyclable material from the outer layer 4.

[0055] The simultaneous use of several cutting tools 2, 2', here two cutting tools 2, 2', makes it possible to simultaneously cover more volume of the outer layer 4, and more particularly more axial surface of outer layer 4, and therefore to improve the efficiency of the process by reducing the cycle time required.

[0056] Furthermore, since the entire material removal operation takes place while maintaining the bandage 1 in a single direction of rotation, here a direction of rotation R20- which is negative by convention on figures 2, 5A, 6A, 7A, 10A, 11A, the transient phases of braking, stopping and acceleration which would otherwise be necessary to reverse the direction of rotation of the support 20 are saved; thus, energy consumption and cycle time are limited.

[0057] In practice, the main axis Z20 will coincide with the central axis of the tire 1, around which the tire 1 forms a toroidal ring, and which therefore corresponds to the axis around which the tire rotates when said tire 1 is in service on a vehicle wheel and rolls on the ground.

[0058] By convention, we will designate as "axial" a direction parallel to the axis considered, here more particularly a direction parallel to the axis of rotation Z20, and as "radial" a direction perpendicular to said axis.

[0059] We will designate by "circumferential" direction a direction of the bandage which is orthoradial with respect to the central axis of the bandage, here therefore orthoradial with respect to the principal axis Z20, that is to say a direction which is contained in a plane normal to the central axis of the bandage and which is, at a point considered of the bandage, perpendicular to the radius which joins the central axis of the bandage to said point considered, or in other words, a direction which, at a point considered of the bandage, is normal to the radial plane which contains the central axis of the bandage and which passes through said point considered.

[0060] The term "radial plane" or "meridian plane" refers to a plane that contains the central axis of the bandage, in this case the principal axis Z20, and which therefore extends on the one hand along the central axis of the bandage, and on the other hand along a radius of the bandage, perpendicular to the central axis.

[0061] By analogy with the Earth, we will conventionally designate as "equatorial plane" P_EQ the plane normal to the central axis of the bandage, here therefore normal to the principal axis Z20, which passes through the middle of the axial range W1 occupied by the bandage 1, and which thus divides said bandage into a first hemisphere H1 and a second hemisphere H2, said second hemisphere H2 being located opposite the first hemisphere H1 with respect to said equatorial plane P_EQ.

[0062] The axial width W1 of the band corresponds to the distance that separates two fictitious gauge planes which are normal to the central axis of the band, here the principal axis Z20, and which are each tangent to the wall 3, respectively at a first axially outermost point of the wall 3, generally located on the outer surface of the first flank 11, and forming a first axial end 11 of the band, and at a second axially outermost point of the wall 3, located axially opposite the first point, and generally located on the surface of the second flank 12, and forming a second axial end 12 of the band 1. The axial range occupied by the band 1, which we can also denote "W1" for convenience, will correspond to the portion of the space delimited axially by, and therefore included between, the two aforementioned fictitious gauge planes.

[0063] By convention, we will designate by "equatorial zone" an axial area of ​​bandage 1 which on the one hand represents less than 35% of the axial area W1 covered by bandage 1, preferably less than 30% of the axial area W1 covered by bandage 1, more preferably less than 25% of the axial area W1 covered by bandage 1, or even less than 20%, less than 15% or even less than 10% of the axial area W1 covered by bandage 1, and which on the other hand contains the equatorial plane P_EQ of the bandage.

[0064] By convention, the direction of rotation R20- will be considered negative when it corresponds to a clockwise direction in figures 1 and 2, and is therefore oriented from bottom to top in figures 6 A, 7 A, 10A and 11 A.

[0065] Conversely, the direction of rotation R20+ would by convention be positive if it corresponded to a counter-clockwise, or "trigonometric," direction of rotation in Figures 1 and 2. However, the installation 40 enabling the implementation of the process, as illustrated in figures 1 and 2, and more particularly the cutting tools 2, 2', are configured here specifically to work with a negative R20- rotation direction, so that only such a negative R20- rotation direction will be considered in what follows.

[0066] Preferably, the rotating support 20 is arranged to hold the bandage 1, preferably uninflated, by the first heel 7 and second heel 8, while leaving the top 10 free.

[0067] The inventors have indeed found that it was thus possible to hold the bandage 1 by the heels 7, 8, while maintaining sufficient firmness of said bandage 1 for the machining operation, without it being necessary to inflate said bandage 1 or to support said bandage 1 by tiles which would come to be placed under the top 10 of said bandage 1.

[0068] It is therefore advantageous to machine bandages 1 which are no longer waterproof, because they have perforations or lacerations, which is common on bandages that have reached the end of their life.

[0069] Preferably, the process, and more particularly the material removal step, will therefore be carried out on an uninflated bandage 1, that is to say a bandage 1 whose radially internal face of the wall 3 is at ambient atmospheric pressure, without overpressure relative to said ambient atmospheric pressure which bathes the support 20 and more generally the workshop in which the installation 40 which allows the process to be carried out is located.

[0070] In addition, the support by the heels 7, 8 allows the same support 20 to easily adapt to bandages 1 of very varied dimensions, and in particular to bandages 1 with very different internal diameters from one bandage 1 to another.

[0071] In this respect, it should be noted that, as illustrated in Figures 1 and 2, the rotary drive support 20 can, for example, be formed by a radially expanding drum 21, having jaws 22 which are able to alternately expand radially centrifugally to engage with the heels 7, 8, thus adopting a diameter corresponding to the internal diameter of the band 1, and retract radially centripetally to release the band 1 after the machining operation.

[0072] As a guide, the rotation speed of the support 20, and therefore of the band 1, during the material removal operations may be between 1 rpm and 5 rpm, for example, equal to 3 rpm. Higher rotational speeds could, of course, be considered, for example, on the order of 10 rpm. However, the aforementioned speeds offer a favorable compromise between the power required for accelerating and braking the support 20, the reliability of process control, and cycle time.

[0073] Preferably, in order to facilitate the evacuation of the material removed from the outer layer 4, and in order to avoid interference of the second cutting tool 2' with the first cutting tool 2, or more generally interference of the second positioning system 42' with the first positioning system 42, and in particular in the equatorial zone of the band 1, the first cutting tool 2 and the second cutting tool 2' shall be offset in azimuth from each other around the main axis Z20, so as to each occupy a distinct angular sector around the main axis Z20.

[0074] The first cutting tool 2 and the second cutting tool 2', and more particularly their respective points of contact with the wall 3 of the bandage 1, may thus preferably be separated from each other in azimuth by at least 30 degrees, preferably by at least 90 degrees, or even by at least 120 degrees, and for example by 180 degrees + / - 20 degrees.

[0075] A positioning at 180 degrees + / - 20 degrees will allow the first and second cutting tools 2, 2' to be substantially diametrically opposed, as illustrated in figures 1 and 2.

[0076] Preferably, as can be seen in figures 1, 2, 12 and 14, the first cutting tool 2 and the second cutting tool 2' are formed respectively by a first cylindrical knife 25 and a second cylindrical knife 25', whose respective circular edges 25 A, 25' A form the cutting edges and are oriented so as to engage the wall 3 in opposition to the chosen direction of rotation R20+, R20-.

[0077] Such cylindrical knives 25, 25' advantageously provide a precise, clean and regular cut, which allows the constituent material of the outer layer 4 to be removed in the form of chips or strips, potentially right up to the reinforcing wires 6.

[0078] The generating axis Z25, Z25', around which each cylindrical knife 25, 25' is considered, rotates at a R25 rotation on itself while the band 1 is itself driven in rotation R20 by its support 20, is advantageously oriented so that said cylindrical knife 25, 25', and more particularly its edge 25A, 25'A, is presented in a substantially tangent manner to the apparent, moving surface of the wall 3, and more preferably slightly oblique with respect to said apparent surface.

[0079] Thus, more preferably, in order to promote the penetration of the edge 25A, 25'A of the cylindrical knife 25, 25' into the wall 3 and to clear the space necessary for the corresponding positioning system 42, 42', the generating axis Z25, Z25' of the cylindrical knife will have, in a plane normal to the main axis Z20, and more particularly in a plane normal to the main axis Z20 passing through the point of the edge 25 A, 25'A which is in contact with the wall 3 and closest to the main axis Z20, an angle of inclination with respect to the tangent to the perimeter of the wall 3, for example an angle of inclination of the order of 15 degrees, as can be seen in the figure 2.

[0080] In order to be able to work simultaneously in consideration of a single direction of rotation R20-, the first and second cylindrical knives 25, 25' each point in the same circumferential direction, so that, here, in figures 1 and 2, the first cylindrical knife 25, located to the right of the main axis Z20, points upwards, against the direction of rotation R20- negative, while the second cylindrical knife 25', diametrically opposite, located to the left of the main axis Z20, points downwards.

[0081] Furthermore, each of the first and second cylindrical knives 25, 25' will preferably be equipped with a sharpening system 45, 45', including for example a sharpening wheel, which will allow the cutting edge to be sharpened automatically during or after the cutting operation.

[0082] The edge 25 A, 25'A forming the cutting edge will preferably be smooth, appearing as a continuous wall, without indentations, as illustrated in figures 1, 2 and 12. Such a smooth edge 25A, 25'A will have in particular the advantage of not having any roughness likely to accidentally catch a reinforcing wire 6.

[0083] Preferably, the cylindrical knife 25, 25' will have a diameter between 100 mm and 300 mm.

[0084] Each of the first and second cylindrical knives 25, 25' can also be associated with a chip evacuation chute 46, 46', as illustrated in Figures 1 and 12, which chute 46, 46' will guide the material removed from the band 1 towards a recovery system, including for example an evacuation conveyor which may itself open directly above a recovery bin into which said conveyor will pour the material extracted from the outer layer 4 of the band 1.

[0085] The first cutting trajectory T2_l causes the first cutting tool 2 to travel, opposite the bandage, a first predetermined axial range W2_l along the main axis Z20, called the "first axial cutting range" W2_l.

[0086] We denote Kl the starting point of the first cutting trajectory T2_l, and Ml the arrival point.

[0087] The second cutting trajectory T2_2 causes the second cutting tool 2' to travel, opposite the bandage, a second predetermined axial range W2_2 along the main axis Z20, called the "second axial cutting range" W2_2.

[0088] We denote K2 as the starting point of the second cutting trajectory, and M2 as the corresponding ending point.

[0089] The "axial path direction" S2_l, S2_2 designates the direction in which the cutting tool 2, 2' considered travels, preferably monotonically, the axial range W2_l, W2_2 during the material removal step, in abscissa along the main axis Z20, and therefore moves over the width of the band, transversely to the circumferential direction of the band 1, starting from a starting axial abscissa, which corresponds to the end of the axial cutting range where the cutting path begins, to arrive at an ending axial abscissa, which corresponds to the other end of the axial cutting range, where the cutting path ends.

[0090] By convention, we can consider that the axial path direction S2_l is positive, and therefore that the cutting tool moves along the increasing abscissas along the main axis Z20, when the cutting tool moves from the second flank 12 to the first flank 11, which corresponds to a direction of movement from the background to the foreground in figures 1 and 2. For convenience, we can denote Z20+ the positive direction of the increasing abscissas of the main axis Z20.

[0091] In theory, one could consider using the first cutting tool 2 to make a first pass, at a given initial depth, and that the second tool cutting tool 2' is used to fit in the wake of the first cutting tool 2' in order to make a second pass, at a second depth greater than the first depth; the second axial cutting range W2_2 would then be superimposed on the first axial cutting range W2_l.

[0092] However, in a particularly preferential way, the first axial cutting range W2_l and the second axial cutting range W2_2 will not be superimposed, but at most partially overlapping axially, and therefore not totally overlapping axially, or even not overlapping axially.

[0093] In a particularly preferential way, the second axial cutting range W2_2 is complementary to the said first axial cutting range W2_l so that the said first and second axial cutting ranges together cover the entire axial range W 1 occupied by the band 1. Thus, it will be possible to cover the entire axial width of the band, during the same material removal step, by the summation of the axial cutting ranges assigned respectively to the first cutting tool 2 and the second cutting tool 2'.

[0094] Preferably, bandage 1 being divided axially into a first hemisphere H1 and a second hemisphere H2 located each on a different side of the equatorial plane P_EQ of the bandage which is normal to Main Tax Z20 and passes through the middle of the axial range W1 occupied by bandage 1, the first cutting tool 2 is assigned to the removal of material in the first hemisphere H1 of bandage 1 while the second cutting tool 2' is assigned to the removal of material in the second hemisphere H2 of bandage 1.

[0095] The machining work is thus advantageously distributed in a substantially equal manner between the two cutting tools 2, 2'.

[0096] This allows, in particular, for balancing the wear of the cutting tools 2, 2'.

[0097] Above all, this optimizes the overall cycle time since each of the first and second cutting tools 2, 2' operates on an individual cycle time which is substantially equal to the individual cycle time of the other cutting tool 2', 2, so that the two cutting tools 2, 2' can work in totally masked time, or almost totally masked time, with respect to each other.

[0098] The first cutting tool 2 and the second cutting tool 2' will preferably work respectively along a first axial path S2_l and a second axial path S2_2 which are of opposite signs, preferably in mirror with respect to the equatorial plane P_EQ, and more preferably each in an axial path which goes from the equatorial plane P_EQ towards the pole of the hemisphere Hl, H2 covered by the cutting tool 2, 2' considered.

[0099] As an example, the first cutting tool 2 follows a first axial path direction S2_l positive, here going from left to right, on figures 6A, 7B, 11 A and 13, while the second cutting tool 2' follows a second axial path direction S2_2 negative, going from right to left on figures 7B, 11 A and 13.

[0100] Preferably, the starting points K1, K2 of the cutting trajectories T2_1, T2_2 will be located axially in the equatorial plane P_EQ, or at least in the vicinity of the equatorial plane, for example in the equatorial zone which, as explained above, contains the axial abscissa of the equatorial plane P_EQ and whose axial width is less than 35%, 30%, 25%, 20%, 15%, or even 10% of the axial range W1 occupied by bandage 1. Thus, preferably, the first cutting trajectory T2_1, and respectively the second cutting trajectory T2_2, cover at least a part of the equatorial zone; that is, the first axial range of cutting W2_1 overlaps axially at least a part of the equatorial zone, and respectively the second axial range of cutting W2_2 overlaps axially at least a part of the zone equatorial.

[0101] According to a preferred implementation possibility, called "machining in contact with the reinforcement layer", the first cutting path T2_l is executed by bringing the first cutting tool 2 into contact with the reinforcement layer 5 and then axially moving the first cutting tool 2 so as to slide the first cutting tool 2 in contact with the reinforcement layer 5, or successive reinforcement layers 5, 5', along the reinforcement wires 6, 6', in at least a part or even all of a chosen hemisphere, here in at least a part or even all of the first hemisphere H1 in figures 6A, 6B, 6C, 7B and 11A.

[0102] Thus, advantageously, in at least a part of this chosen hemisphere, and preferably in the whole of said hemisphere, the entire thickness E4 of the outer layer 4 will be removed, and the maximum amount of available material will therefore be recovered.

[0103] Of course, in order not to tear the reinforcing threads 6, the first cutting tool 2 must traverse the chosen hemisphere in the correct direction, taking into account the orientation A6, A6' of the reinforcing threads. This means that the tool must move in the direction that tends to press the points formed by the ends of said reinforcing threads 6, 6' against the reinforcing layer 5, 5' and the bandage carcass, at the level of the edge(s) 51, 5'1 of the reinforcing layer(s) 5, 5' in question. This must occur when the cutting tool 2 crosses said edge(s) 51, 5'1 within the selected axial cutting range W2_l, here in our example in the first hemisphere Hl. This must be done in such a way that the first cutting tool 2 does not cut the reinforcing threads 6, 6' against the grain and thus does not tear them. the reinforcing wires 6, 6', in particular at the ends of the reinforcing wires which form the selvage(s) 5 1, 5' 1 of the reinforcing layer(s) 5, respectively,5' that the cutting tool 2 successively crosses by traversing axially the hemisphere in question.

[0104] Therefore, the method according to the invention will preferably include a step of identifying the orientation of the reinforcing wires 6, 6', during which the orientation A6, A6' of said reinforcing wires 6, 6' is identified with respect to a reference direction called "circumferential equatorial line" L_EQ which corresponds to the intersection of the radially external surface of the reinforcing layer 5 with the fictitious "equatorial plane" P_EQ which, as indicated above, is normal to the principal axis Z20, and therefore to the central axis of rotation of the bandage, and passes through the middle of the axial range W 1 occupied by said bandage 1.

[0105] More specifically, the orientation A6 may correspond to the angle called "sheet angle" A6_ang which, with respect to the equatorial circumferential line L_EQ, are formed by the reinforcing wires 6 of a reinforcing sheet 5 located in the apex 10 of the bandage 1, that is to say the angle according to which each reinforcing wire 6 is oriented in a loop around a fictitious radial line which is perpendicular to the main axis Z20 and which passes through the intersection of said reinforcing wire 6 with the equatorial circumferential line, as illustrated in Figure 6A.

[0106] The orientation A6, A6' of the reinforcing wires 6, 6' can typically be defined by means of two parameters, namely the sign of the sheet angle A6_ang, Aô' ang and the value of said sheet angle A6_ang, Aô' ang, taking, for example, the equatorial circumferential line L_EQ as a reference, whose orientation is considered to be zero degrees. By convention, the sheet angle Aô ang, Aô' ang can be considered to be negative when, as is the case in figure 6A, it deflects the reinforcing wire 6, 6' at an acute angle to the left, and therefore in the trigonometric, counter-clockwise, loop direction, relative to the equatorial circumferential line L_EQ, and the sheet angle A6_ang, Aô' ang is on the other hand positive when it deflects the reinforcing wire 6 at an acute angle to the right, therefore in the clockwise loop direction.

[0107] The identification of the A6, A6' orientation of the reinforcing wires can be carried out for each bandage 1 by any appropriate means, for example by querying a database pre-established by the bandage manufacturer and which contains information on the structure of the bandage 1 associated with an identifier of the bandage or the batch of manufacture of the bandage, or by carrying out an X-ray radiography of the bandage, or by carrying out a sounding in which the bandage 1 is locally excavated, preferably in the equatorial zone, for example by digging an annular trench using one of the cutting tools 2, 2', until the reinforcing wires 6 are made visible, the orientation of which A6 can then be identified, for example, using a laser profilometer or a camera associated with an image analysis system.

[0108] The cutting tool 2 is considered to travel along the reinforcing wires 6 "in the correct direction" when the relative displacement of the cutting tool 2 with respect to the reinforcing layer 5, which can be conveniently represented as a velocity vector V2 in Figure 6A, has: - on the one hand, a circumferential displacement component V2_circ, induced by the rotation R20 of the bandage 1, which has the same sign as the circumferential component Aô circ of the orientation A6 of the reinforcing wires 6, considered when traversing said reinforcing wires 6 from the equatorial plane P_EQ towards the pole of the hemisphere considered, here, therefore, in the case of the first hemisphere Hl, towards the first axial end 5 1 of the reinforcing layer 5, and more generally towards the first axial end 1 1 of the bandage 1, - and on the other hand, an axial displacement component V2_ax, which corresponds to the chosen axial path direction S2_l, which axial displacement component V2_ax has the same sign as the axial component A6_ax of the orientation A6 of the reinforcing wires 6, considered when traversing said reinforcing wires 6 from the equatorial plane P_EQ towards the pole of the hemisphere considered, here, therefore, in the case of the first hemisphere Hl, towards the first axial end 5 1 of the reinforcement layer 5, and therefore more generally towards the first axial end 1 1 of the bandage 1.

[0109] Thus, if we consider at a given instant, in a plane frame whose origin corresponds to the point of contact of the cutting tool 2, and more particularly of the cutting edge of the cutting tool 2, with the reinforcing sheet 5, and more particularly with a reinforcing wire 6, at the instant considered, and whose base is defined by an axial vector, parallel to the principal axis Z20, and a circumferential vector, perpendicular to the axial vector, then the velocity vector V2 of the cutting tool 2 which characterizes, at the point of contact between the cutting tool 2 and the reinforcing sheet 5, the displacement of the cutting tool 2 with respect to the surface of the reinforcing sheet 5, is located in the same quadrant of said frame as the direction vector tangent to the reinforcing wire 6 passing through the origin of the frame at the instant considered, for example in the Southeast quadrant in Figure 6A, and points in the same direction as said direction vector tangent to the reinforcing wire 6,for example, to the right and downwards in figure 6A.

[0110] More particularly, the invention will allow, by a judicious choice of cutting parameters, and more particularly by a judicious selection of the hemisphere and therefore of the axial path direction S2_l, taking into account on the one hand the direction of rotation R20-, which direction of rotation R20- is generally imposed, and on the other hand the identified orientation A6 of the reinforcing wires 6, to ensure that the circumferential components V2_circ and respectively axial components V2_ax of the velocity vector V2 representing the displacement of the cutting tool 2 with respect to the reinforcing layer 5 are, at the moment when said cutting tool 2 axially crosses the axial end 51 of the reinforcing layer 5 located in the hemisphere considered, and therefore crosses the free ends of the reinforcing wires 6, of the same signs as the circumferential components A0_circ, respectively axial components A6_ax, of the direction vector, tangent to the reinforcing wires 6,which characterizes the A6 orientation of said reinforcing wires at the axial end 5 1 of said reinforcing layer 5.,

[0111] In the part of the description that follows and which concerns the implementation of machining in contact with the reinforcement layer, it will be considered, for convenience of description, that the machining in contact with the reinforcement layer is carried out by the first cutting tool 2 in the first hemisphere Hl, here located on the right in figures 6A, 6B, 6C, 7B and 11A.

[0112] It will be understood that when the reinforcing wires 6 have an oblique A6 orientation and are presented in the correct direction in the first hemisphere Hl, here for example at at the level of the first selvedge 5 1 of the first reinforcement layer 5, taking into account the direction of rotation R20- chosen, here a negative direction of rotation R20-, then, these same reinforcing wires 6 will be presented in the wrong direction in the opposite second hemisphere H2, here for example at the level of the second selvedge 5 2 of said first reinforcement layer, with regard to said direction of rotation R20- chosen.

[0113] Therefore, it will be necessary to avoid sliding the second cutting tool 2' into contact with the reinforcement layer 5 in the second hemisphere H2, at least in the axial range which contains the second edge 5 2 of said reinforcement layer 5.

[0114] For this purpose, the second cutting trajectory T2_2 preferably presents, at least on a part of the second hemisphere H2, a radial centrifugal shift Delta_T2 with respect to the first cutting trajectory T2_l, so as to preserve a certain residual overthickness Delta_4 of outer layer 4 in the second hemisphere H2 with respect to the first hemisphere Hl, as can be seen in figures 7A and 7B.

[0115] Advantageously, a residual safety thickness can thus be preserved in the second axial cutting range W2_2, and therefore more particularly here in the second hemisphere H2, where the second cutting tool 2' will travel along the reinforcing wires 6, 6' against the grain, so that the cutting tool 2' remains at a distance from said reinforcing wires 6, 6' in the area or areas at risk, in particular when crossing the axial position of the ends of said reinforcing wires 6, 6', while, conversely, the first cutting tool 2 will be able to slide in contact with the reinforcing wires 6, 6' in the other axial cutting range, here the first axial cutting range W2_l, and therefore in the first hemisphere Hl, where said reinforcing wires 6, 6' are oriented in the correct direction taking into account the direction of rotation R20- and the direction of axial travel S2_l.

[0116] In other words, to maintain the benefit of time and energy savings from machining using a single direction of rotation, more precautions can be taken in the H2 hemisphere where the reinforcing wires 6, 6' are run against the grain than in the Hl hemisphere where the reinforcing wires 6, 6' are run in the right direction, by machining the outer layer 4 less deeply in the second H2 hemisphere than in the first Hl hemisphere.

[0117] This may result in exposing the reinforcing layer 5, and more particularly the reinforcing wires 6, in the first hemisphere H1, and maintaining a slight residual thickness E4 of outer layer 4 which covers the reinforcing layer 5 over at least part or even all of the portion of the reinforcing layer 5 which extends into the second hemisphere H2, as can be seen in figures 7A and 7B.

[0118] As a guideline, the radial centrifugal shift Delta_T2 will preferably be between 1 mm and 3 mm.

[0119] It is possible to implement an evolving, and more preferably progressive, radial centrifugal offset Delta_T2, for example which will be zero at the abscissa of the equatorial plane P_EQ, at the starting point K2 of the second cutting trajectory T2_2, and which will become positive from a certain axial distance from the equatorial plane P_EQ, which in this case precedes the axial position of the second edge 5 2 of the reinforcement layer 5 in the second direction of axial path S2_2, so that the second cutting tool 2' will move away from the reinforcement wires 6, in order to create the overthickness Delta_4, and thus leave a residual thickness of outer layer 4, only when the second cutting tool 2' approaches the second edge 5 2 of the reinforcement layer 5 located in the second hemisphere H2 and passes over said second edge 5_2.

[0120] Preferably, the first positioning system 42 forms a master positioning system which executes a first cutting path T2_l according to which said first positioning system 42 axially displaces the first cutting tool 2 from the equatorial plane P_EQ by sliding said first cutting tool 2 in contact with the reinforcing layer 5, along the reinforcing wires 6, while the second positioning system 42' forms a slave positioning system in which the execution of the second cutting path T2_2 is deferred in time, according to which said second positioning system 42' axially displaces the second cutting tool 2' from the equatorial plane P_EQ, relative to the execution of the first cutting path T2_l.

[0121] Thus, although the first and second cutting trajectories T2_l, T2_2 take place essentially simultaneously, over the same period of time, the first cutting trajectory T2_l preferentially benefits from a slight lead, which notably allows the first cutting tool 2 to reveal any remarkable features present in the first hemisphere Hl, such as the first edges 5 1, 5' 1 of reinforcing layers 5, 5', before the second cutting tool 2', in turn reaches analogous remarkable elements, such as second edges 5 2, 5' 2, which are found in the second hemisphere H2, mirroring the remarkable elements of the first hemisphere H1 with respect to the equatorial plane P_EQ.

[0122] When the bandage 1, and more specifically the outermost reinforcing layer 5, exhibits symmetrical arrangement with respect to the equatorial plane P_EQ, as is frequently the case in practice, such a precaution makes it possible to anticipate the crossing, in the second hemisphere H2, of potential obstacles, such as edges or ridges in the reinforcing layer 5, at which point the reinforcing wires 6, due to their orientation A6, present, in said second hemisphere H2, increased vulnerability to tearing compared to the same reinforcing wires 6 considered in the first hemisphere H1. The invention therefore makes it possible to take, in a timely manner, the necessary measures to adapt the second cutting trajectory T2_2 in order to prevent tearing of the reinforcing wires 6 in the second hemisphere H2.

[0123] Thus, preferably, we detect a crossing by the first cutting tool 2 of a first edge 5 1 of the reinforcement layer 5 in the first hemisphere H1, and we control the second positioning system 42' so as to introduce into the second cutting trajectory T2_2 a centrifugal radial offset Delta_T2 which allows the second cutting tool 2' to pass radially at a distance from the reinforcement layer 5 when said second cutting tool 2' passes, in the second hemisphere H2, through an abscissa which is the mirror image, with respect to the equatorial plane P_EQ, of the abscissa of the first edge 5 1 crossed by the first cutting tool 2.

[0124] In this way, the second cutting path T2_2 can keep the second cutting tool 2' as close as possible to the reinforcement layer 5. The second positioning system 42' initially adopts a follower behavior, reproducing a mirror image of the first cutting path T2_1 and thus sliding the second cutting tool 2' into contact with the reinforcement layer 5. It then adopts an adjusted behavior, deviating from the mirror image of the first cutting path T2_1 by slightly retracting the cutting tool by the chosen value of the centrifugal radial offset Delta_T2, relative to the mirror image of the first cutting path T2_1, when crossing the second edge 52 located in the second hemisphere H2, in order to move the second cutting tool 2' away from the reinforcement layer 5 to a necessary and sufficient extent to maintain an excess thickness of protective material Delta_4 and thus not catch the reinforcement wires 6.

[0125] The centrifugal radial shift Delta_T2 can be introduced in the form of a step or several successive steps, at a given axial abscissa or respectively successive axial abscissas, or in a progressive form, for example by means of a ramp which extends over a given axial range.

[0126] The second positioning system 42' will advantageously control the second cutting tool 2' in radial position, from the radial positions identified along the first cutting path T2_l, where appropriate corrected for the applicable centrifugal offset value Delta_T2.

[0127] Any appropriate means may be used to delay the start of the execution of the second cutting trajectory T2_2 relative to the start of the execution of the first cutting trajectory T2_1.

[0128] For example, this can be used to trigger the axial displacement of the second cutting tool 2' in the second hemisphere H2 along the second cutting trajectory T2_2: - when the first cutting tool 2 crosses, in the first hemisphere Hl, a predetermined axial abscissa threshold in distance from the equatorial plane P_EQ, - or at the end of a predetermined delay from the triggering of the axial movement of the first cutting tool 2 along the first cutting trajectory T2_l.

[0129] The detection of the crossing of a notable element, here of a 5 1, 5' 1 edge of reinforcement layer 5, 5' in the first hemisphere Hl during the passage of the first cutting tool 2 at the axial abscissa of said notable element, or just after the passage of said cutting tool 2 at the axial abscissa of said notable element, may be carried out by any appropriate means, in particular by an optical detection device 50 such as a laser rangefinder which measures the distance of the wall 3 with respect to the main axis Z20, a profilometer or a camera associated with an image analysis tool.

[0130] Preferably, the first cutting trajectory T2_l is executed by bringing the first cutting tool 2 into contact with the reinforcement layer 5 and then applying radial force to the first cutting tool 2 while axially moving the first cutting tool 2, so as to slide the first cutting tool 2 into contact with the reinforcing layer 5, along the reinforcing wires 6, in the first hemisphere Hl.

[0131] Such radial force control allows the first cutting tool 2 to remain permanently in contact with the wall 3, and in compression against said wall 3, and more particularly in contact with the reinforcement layer 5, during the rotation R20 of the tire 1, even in the event of irregularities in curvature or centering causing out-of-roundness, and also allows the first cutting tool 2 to automatically accommodate, by dynamically adapting its radial position, the variations in the surface of the reinforcement layer 5, in particular the possible curvature of said reinforcement layer 5 as well as the bumps formed by the edge(s) 51, 5'1 of the reinforcement layer(s) 5 traversed by the first cutting tool 2.

[0132] For example, the first cutting tool 2 can be controlled by radial force so that the first cutting tool 2 exerts against the wall 3, and more particularly against the reinforcement layer 5, 5', a centripetal radial force of constant intensity, while said first cutting tool moves along the main axis Z20.

[0133] To achieve radial force control, a pneumatic cylinder can be used, for example, to radially press the first cutting tool 2 against the wall. 3, and more specifically against the reinforcing layer 5, 5', with the desired radial force intensity. A pneumatic cylinder ensures both good control of the force intensity and a flexible, floating pneumatic suspension of the first cutting tool 2, which allows the latter to remain constantly in contact with the wall 3, and more specifically with the reinforcing layer 5, 5'.

[0134] The radial positions adopted by the first cutting tool 2 along the first cutting trajectory T2_l controlled by radial force, when said first cutting tool 2 follows the surface of the reinforcement layer 5 and moves axially, can advantageously serve as a reference to determine the corresponding radial positions of the second cutting tool 2', and thus construct a second adapted cutting trajectory T2_2, from the first effective cutting trajectory T2_l, integrating, if necessary, the corrections provided by the applicable centrifugal radial offsets Delta_T2, to control the second cutting tool 2' in radial position.

[0135] In this respect, preferably, during the execution of the first cutting trajectory T2_l, radial positions are measured which are successively adopted by the first cutting tool 2 controlled in radial force, along the first cutting trajectory T2_l in contact with the reinforcement layer 5, and the second cutting tool 2' is controlled in radial position, from the measured radial positions of the first cutting tool 2, so as to be able to introduce a centrifugal radial offset Delta_T2 in the second cutting trajectory T2_2 if a radial position variation of the first cutting tool 2 is detected in the first hemisphere Hl which is representative of the axial crossing, by the first cutting tool 2, of an edge 5 1 of the reinforcement layer 5.

[0136] Thus, it is the first cutting tool 2 itself that will be used to detect the crossing by the first cutting tool 2 of a first edge 5 1, 5' 1 of a reinforcement layer 5, 5' in the first hemisphere Hl, acting like a probe whose radial position is monitored in order to detect the variations in radial position induced by the arrangement of the reinforcement layer(s) 5, 5'.

[0137] The correction of the second cutting trajectory T2_2 will then be triggered in response to the detection of a 5 1 edge in the first hemisphere H1 to preserve the integrity of the reinforcement layer 5, and of the second cutting tool 2', when crossing the equivalent 5 2 edge in the second hemisphere H2.

[0138] Furthermore, the method according to the invention preferably includes a preliminary step of analyzing the bandage during which the radial distance known as the "radial envelope distance" D0_ply is evaluated, at which, with respect to the main axis Z20, in the absence of radial stress exerted on the wall 3 by the cutting tools 2, 2', the radially external limit of the reinforcing wires 6 of the reinforcing layer 5 located immediately under the outer layer 4 is situated, then a cutting trajectory definition step during which the first cutting trajectory T2_l, and preferably also the second cutting trajectory T2_2, are defined from the radial envelope distance D0_ply, by fixing the radial position of the starting point Kl of the first cutting trajectory T2_l, and preferably also the radial position of the starting point K2 of the second cutting trajectory T2_2,at a radial distance from the main axis Z20 which is less than the radial envelope distance D0_ply of a non-zero value called the "nominal bend value" D bend, as illustrated in Figure 14.

[0139] The said nominal value of deflection D bend is preferably between 1 mm and 5 mm, more preferably between 2 mm and 5 mm, for example equal to 3 mm.

[0140] As illustrated in Figure 14, the application of a nominal value of deflection D bend allows the cutting tool 2, 2' to cause a radial indentation of the wall 3 by elastic deformation in centripetal radial bending of the reinforcing wires 6, 6', and thus creates a radial compression prestress of the cutting tool 2 against the outer layer 4 supported by the reinforcing wires 6, 6', which allows the outer layer 4 to be scraped as close as possible to the reinforcing wires 6, 6', and more preferably in contact with said reinforcing wires 6, 6', taking into account where appropriate the degree of sharpness of the cylindrical knife 25, 25' forming the cutting tool 2, 2'.

[0141] Such pre-stress also makes it possible to compensate for any defects in centering or roundness of the band 1, and therefore allows the cutting tool 2, 2' to reach the reinforcement layer 5 over the entire circumference of said band 1.

[0142] Preferably, the starting points Kl, K2 of the cutting trajectories are located in the equatorial zone of the bandage 1, preferably at the axial abscissa of the equatorial plane P_EQ, so that the nominal value of bend D applies in practice to the radially outermost crest line of the reinforcement layer 5 and the reinforcing wires 6.

[0143] In view of the above, if Ton opts for the implementation option known as "machining in contact with the reinforcement layer", one can consider one or the other of the four scenarios below, designated respectively as "scenario 1", "scenario 2", "scenario 3", and "scenario 4".

[0144] SCENARIO 1

[0145] The starting point Kl of the first cutting trajectory T2_l is fixed at an axial position contained in the equatorial zone, preferably in the equatorial plane P_EQ, and at a radial distance from the main Taxe Z20 which, as illustrated in Figure 14, is less than the radial distance of the envelope D0_ply, of a value called the "nominal deflection value" D bend chosen which is between 2 mm and 5 mm, for example equal to 3 mm, so that the first cutting tool 2 causes a radial indentation of the wall 3 by elastic deformation in bending of the reinforcing wires 6 and is thus radially prestressed against the outer layer 4 supported by the reinforcing wires 6.

[0146] We then opt for a first straight cutting trajectory T2_l, the path of which forms, from the starting point Kl, a straight line parallel to the main axis Z20. Thus, the first cutting tool 2 evolves axially while remaining at a constant radial distance from the main axis Z20.

[0147] Advantageously, when the wall has a curved shape and the reinforcement layer 5, 5' tends to be folded back towards the main axis Z20 at the shoulders of the bandage 1, such a scenario allows to recover a maximum of material in the equatorial zone, while passing the first cutting tool 2 at a radial distance from the edge of the reinforcement layer 5, 5', in particular at the shoulders.

[0148] Preferably, the second cutting path T2_2 is also rectilinear and parallel to the principal axis Z20, a mirror image of the first cutting path T2_l with respect to the equatorial plane P_EQ, starting from a starting point K2 located radially at a distance from the principal axis that is either, preferably, identical to that of the starting point Kl of the first cutting path or, possibly, offset by a centrifugal radial offset value Delta_T2. The second cutting tool 2' is radially servo-controlled.

[0149] The second T2_2 cutting trajectory therefore has, in the second hemisphere H2, the same effects and the same consequences as the first T2_l cutting trajectory in the first hemisphere H1.

[0150] Such a scenario 1 is particularly suited to the machining of a band which has the first implantation scheme mentioned above and illustrated in figures 3, 4, and 6A.

[0151] Such a scenario 1 would also be well suited to machining a bandage that has a (third) weave pattern in which, unlike the weave pattern, the second reinforcing wires 6' of the second reinforcing layer 5' have an orientation A6' opposite to the orientation A6 of the first reinforcing wires 6, so that, in the first hemisphere, the first edge 5' of the first reinforcing layer 5 would be correctly oriented towards the first cutting tool 2, while the first edge 5' of the second reinforcing layer 5' would be oriented in the wrong direction. Indeed, a straight path, executed opposite a wall 3 whose apex 10 is radially more salient than its shoulders, allows the first cutting tool 2 to come into contact with the selvedge 5 1 of the first reinforcement layer 5, in the right direction, and at a slight radial distance from the selvedge 5' 1 of the second reinforcement layer 5', avoiding catching the second reinforcement threads 6'.

[0152] SCENARIO 2

[0153] Identical to scenario 1, except that the first cutting trajectory T2_l is curved, according to a predetermined curvature, the first cutting tool 2 being servo-controlled in radial position.

[0154] The second cutting tool 2' is also servo-controlled in radial position according to a second cutting trajectory T2_2 also curved, and which integrates, if necessary, with respect to the first cutting trajectory, a centrifugal offset value Delta_T2.

[0155] SCENARIO 3

[0156] As in scenario 1, the starting point Kl of the first cutting trajectory T2_l is fixed at an axial position contained in the equatorial zone, preferably in the equatorial plane P_EQ, and at a radial distance from the main axis Z20 which is less than the radial envelope distance, of a value called "nominal deflection value" D chosen which is between 2 mm and 5 mm, for example equal to 3 mm, so that the first cutting tool 2 causes a radial indentation of the wall 3 by elastic deformation in bending of the reinforcing wires 6 and is thus prestressed radially against the reinforcing layer 5.

[0157] On the other hand, this time we opt for a first cutting trajectory T2_l which, unlike scenario 1, implements a servo control of the first cutting tool 2 in radial force, and no longer in radial position, while the first cutting tool moves axially.

[0158] Thus, the first cutting tool 2 slides into contact with the reinforcement layer 5, and more particularly into contact successively with the first reinforcement layer 5 and then with the second underlying reinforcement layer 5', in the first hemisphere Hl, as illustrated in figures 6 A, 6B and 6C.

[0159] This maximizes material recovery by exposing the 5, 5' reinforcement layer and the 6, 6' reinforcement wires.

[0160] The second cutting tool 2' is radially servo-controlled and executes a second cutting path T2_2, which is calculated, and preferably mirrored, from the first cutting path T2_l, specifically from the radial positions of the first cutting path T2_l. This path is adjusted when necessary by introducing a centrifugal radial offset Delta_T2 over all or part of the second hemisphere H2, as illustrated in Figures 7A and 7B. In practice, such a centrifugal radial offset Delta_T2 is introduced at least at the abscissas corresponding to edge crossings 5_2, 5'_2 in the second hemisphere H2.

[0161] Thus, we also recover a maximum of available material in the second hemisphere H2, while avoiding taking the corresponding 5 2, 5' 2 edges against the grain.

[0162] Such a scenario 3 is particularly well suited to the machining of a tire 1 presenting the first layout scheme of figures 3, 4 and 6A, since it allows in particular the first cutting tool 2 to slide successively in contact with the first reinforcement layer 5 then with the second reinforcement layer 5', and to cross successively the edge 5 1 of the first reinforcement layer then the edge 5' 1 of the second reinforcement layer, since these edges 5 1, 5' 1 are both in the right direction.

[0163] SCENARIO 4

[0164] This is a variant of scenario 3, applied to a bandage with the second implantation scheme described above with reference to figures 8 and 9, a variant in which the radial centrifugal offset Delta_T2 is added simply towards the end of the second cutting trajectory T2_2, just to allow the second cutting tool 2' to cross the second end 5 2 of the first reinforcement layer 5, leaving, as indicated in dotted lines on figure 1 IB, a very slight overthickness Delta_4 of outer layer material 4 which covers the axial end, and therefore the second edge 5 2, of the first reinforcement layer 5.Thus, the second cutting tool 2 does not risk peeling the reinforcing wires 6 at the end of the continuous spirally wound strip, and therefore at the second selvage 5 2, where said continuous strip, although the angle A6_ang of the reinforcing wires 6 is small or even substantially zero, is, in absolute terms, taken in the wrong direction due to the negative direction of rotation R20-.

[0165] The first cutting tool 2, approaching the first reinforcement layer 5 in the correct direction, is able to remain in contact with said first reinforcement layer 5 throughout the first hemisphere H1, and to cross without damage the first edge 51 of said first reinforcement layer 5.

[0166] According to a preferred implementation possibility, called "machining under the bottoms of the grooves", the cutting trajectories T2_l, T2_2 will be defined in such a way that the cutting tools 2, 2' reach, in the outer layer 4, intermediate depths, closer to the main axis Z20 than are the bottoms 61B of the grooves 61, but in centrifugal radial retreat from the reinforcement layer(s) 5, 5', and in particular from the first radially outermost reinforcement layer 5, in order to avoid any contact between the cutting tool 2, 2' and the reinforcing wires 6, 6', as illustrated in Figure 13.

[0167] Such an implementation is particularly suited to situations in which it is desired to machine a bandage 1 having a first reinforcing layer 5 which is relatively fragile, because it is relatively thin and / or has reinforcing threads 6 made of polymer material, or in situations in which the architecture of the bandage 1, and in particular of the reinforcing layer 5, is not known, or is poorly identified, so that there remains a doubt about how to machine the bandage 1 without risk to the installation 40.

[0168] Thus, such an implementation may be particularly interesting for machining certain tires used by passenger vehicles and whose reinforcement layer 5 forms a textile ridge that we wish to avoid cutting or perforating.

[0169] Such machining under the bottoms of the grooves can use as a reference, to fix the cutting trajectories T2_l, T2_2, the radial distance of envelope D0_ply, provided that this can be determined without damaging the reinforcement layer 5. The cutting tools 2, 2' can then be positioned in centrifugal radial retreat from the radial distance of envelope D0_ply, for example from 1 mm to 3 mm in centrifugal radial retreat from the radial distance of envelope D0_ply.

[0170] However, preferably, the depth of the bottoms of the 61B grooves will be taken as a reference, since the 61 grooves and their bottoms 61B are advantageously visible directly on the apparent surface of the wall 3, and therefore their characteristics can be measured without it being necessary to dig the outer layer 4.

[0171] Preferably, the process includes a preliminary step of analyzing the band during which the radial distance, called the "radial reference groove bottom" DO groove, is evaluated, at which, with respect to the main axis Z20, in the absence of radial stress exerted on the wall 3 by the cutting tools 2, 2', the bottom 61B of at least one of the grooves 61 is located, then a cutting trajectory definition step, during which the first cutting trajectory T2_1 is defined, and preferably also the second cutting trajectory T2_2, from the radial reference groove bottom DO groove.

[0172] More specifically, we can fix the cutting trajectories T2_l, T2_2, and more specifically their respective starting points Kl, K2, at a radial distance from the main axis Z20 which is less than the radial reference of the groove bottom DO groove, by a chosen offset value D_in.

[0173] The said offset value D_in is, in absolute value, non-zero, to force the cutting tool 2, 2' to penetrate the outer layer 4 under the groove bottoms 61B, and strictly less than the gap between the groove bottom reference DO groove and the radial envelope distance D0_ply, so that the cutting tool 2, 2' cannot reach the reinforcing layer 5, and therefore leaves a slight thickness E4 of protective outer layer on the reinforcing layer 5.

[0174] The offset value D_in can, for example, be between 1 mm and 3 mm.

[0175] The radial reference of the DO groove can be measured by any suitable device, in particular an optical detection device 50, such as a profilometer, a laser rangefinder, etc., which scans the wall 3 and whose position relative to the main axis Z20 is known.

[0176] More specifically, to implement machining under the bottom of the grooves, one can choose one of the three scenarios below, respectively noted "scenario 5", "scenario 6", and "scenario 7".

[0177] SCENARIO 5

[0178] The starting point Kl of the first cutting trajectory T2_l is fixed, preferably at an axial position within the equatorial zone, more preferably in the equatorial plane P_EQ, at a radial distance from the principal axis Z20 that is less to the radial reference of the bottom of the groove DO groove, of a chosen offset value D_in which is non-zero, offset value D_in which can be for example between 1 mm and 3 mm, and we opt for a first straight cutting trajectory T2_l, whose trace forms, from the starting point Kl, a straight line parallel to the main axis Z20.

[0179] The first cutting tool 2 thus travels the first hemisphere at a constant distance, here equal to DO groove - D_in, from the main axis Z20.

[0180] The second cutting trajectory T2_2 is then preferably also straight and parallel to the main axis Z20, and is preferably carried out at the same radial distance from said main axis Z20 as the first cutting trajectory T2_l.

[0181] SCENARIO 6

[0182] As with scenario 5, the starting point Kl of the first cutting trajectory T2_l is fixed, preferably at an axial position contained in the equatorial zone, more preferably in the equatorial plane P_EQ, at a radial distance from the main axis Z20 which is less than the radial reference of the groove bottom DO groove, by a chosen offset value D_in which is non-zero, offset value D_in which can for example be between 1 mm and 3 mm.

[0183] On the other hand, this time we opt for a first curved cutting trajectory T2_l presenting a predetermined curved path which, in a radial plane containing the main axis Z20, presents a concave shape with respect to the main axis Z20.

[0184] This scenario 6 allows for improved material recovery at the shoulders, while maintaining, compared to reinforcement layers 5, 5', a safety thickness E4 at every point across the width of the bandage.

[0185] The same applies to the second cutting trajectory T2_2, which is the mirror image of the first cutting trajectory T2_l with respect to the equatorial plane P_EQ.

[0186] SCENARIO 7

[0187] According to a preferred feature which may constitute an invention in its own right, a fictitious curved interpolation line is determined which passes through the respective bottoms 61B of several grooves 61, preferably through the bottoms of all the grooves distributed axially in the area of ​​the external layer 4 concerned by the cutting trajectory T2_l, T2_2 considered, and we opt for a first curved cutting trajectory T2_l which is parallel to the fictitious interpolation curve line, and closer to the main axis Z20 than said fictitious interpolation curve by a chosen offset value D_in which is non-zero, offset value D_in which can be for example between 1 mm and 3 mm.

[0188] The cutting trajectories T2_l, T2_2 thus faithfully follow the actual trace of the groove bottoms 61B of the band 1 concerned, while passing just below the groove bottoms 61B, in the solid part of the outer layer 4, and remaining radially at a safe distance from the reinforcement layers 5, 5'.

[0189] In this way, the amount of material recovered is optimized on a case-by-case basis for each bandage, while guaranteeing the absence of interference between the reinforcing threads 6, 6' and the tools, and therefore the preservation of the integrity of the reinforcing layers 5, 5' and the cutting tools 2, 2'.

[0190] Preferably, whether one opts for the implementation option in which at least one of the cutting tools 2, 2', or even each of the first and second cutting tools 2, 2', slides in contact with the reinforcing layer 5, or for the implementation option in which each of the cutting tools 2, 2' is held back, at a radial distance from the reinforcing layer 5, the process includes, prior to the material removal step during which the first and second cutting tools 2, 2' act simultaneously, a trenching step, during which the first cutting tool 2 is axially positioned at an axial abscissa within an axial range that, on the one hand, represents less than 35% of the axial range W1 covered by the band 1, preferably less than 30% of the axial range W1 covered by the band 1, or even less than 25%, less than 20%, less than 15%, or even less than 10% of the axial W1 range covered by bandage 1,and which on the other hand contains the equatorial plane P_EQ of the bandage 1, that is to say that the first cutting tool 2, and more particularly the central axis Z25 of the first knife 25, is positioned in the equatorial zone, more preferably the first cutting tool 2 is positioned axially at the axial abscissa of the equatorial plane P_EQ, then, while the bandage 1 is driven in rotation R20 around the principal axis Z20, here in this case in the direction of rotation R20- negative, the first cutting tool 2 is engaged in the internal layer 4, according to a centripetal radial penetration movement, so as to dig a circumferential trench 27 located at the chosen axial abscissa.

[0191] Advantageously, the starting point Kl of the first cutting path T2_l followed by the first cutting tool 2 and the starting point K2 of the second cutting path T2_2 followed by the second cutting tool 2' are then preferably both located inside said trench 27.

[0192] Advantageously, the material extracted from the outer layer 4 during the digging of the trench 27 can be advantageously recovered, in the same way as the material which will then be taken during the execution of the first and second cutting trajectories T2_1, T2_2, and can even represent up to 30% or even 35% of the total material recovered by the process according to the invention.

[0193] Furthermore, by fixing the starting points Kl, K2 in the trench 27, and therefore in the equatorial zone, we allow the cutting tools 2, 2' to be pre-positioned from the outset at the appropriate axial abscissa, and at the appropriate depth of cut, and to effectively attack the outer layer 4, during their respective axial movements in the hemispheres Hl, H2.

[0194] In addition, it is advantageous to dig the trench 27 until the first cutting tool 2 reaches the reinforcing layer 5, and thus make the reinforcing wires 6 visible.

[0195] In this case, it will be advantageous to detect the orientation A6 of the reinforcing wires 6 by observing the apparent surface of the reinforcing layer 5, which forms the bottom of the exploration trench 27, for example by means of an optical detection device 50.

[0196] Similarly, we can thus determine the radial distance of envelope D0_ply.

[0197] Furthermore, preferably, during braking phases aimed at slowing down the rotational speed of the support 20, energy is recovered by means of a converter, such as an alternator, coupled to said support 20.

[0198] More specifically, for simplicity of design, during braking phases the electric motor which is intended to drive the support 20 in rotation R20 can be used in generator mode.

[0199] This will advantageously allow for energy savings, by converting the kinetic energy of the support 20 and the bandage 1 into electrical energy.

[0200] Of course, the invention also relates to an installation 40 enabling the implementation of a process as described above.

[0201] The installation 40 thus includes, as can be seen in figures 1 and 2, a rotating support 20 which is arranged to receive the tire 1, which rotating support 20 is mounted in rotation on a frame 30 around a main axis Z20, here horizontal, and associated with a drive system 41, preferably including an electric motor, which allows to drive said rotating support 20, and therefore the tire 1, in rotation R20 on itself around said main axis Z20, according to a determined direction of rotation R20+, R20-, here by convention a negative direction of rotation R20-.

[0202] The installation 40 also includes a first cutting tool 2, preferably formed by a first cylindrical knife 25, and a second cutting tool 2', separate from the first cutting tool 2, and preferably formed by a second cylindrical knife 25'.

[0203] The installation 40 further includes a first positioning system 42 which carries the first cutting tool 2, preferably at the end of a first robotic arm 44, and which allows the positioning and movement of said first cutting tool 2 relative to the frame 30, and more particularly relative to the main axis Z20, so as to make the first cutting tool 2 follow a first cutting path T2_l while the support 20 drives the band 1 in rotation R20, so as to remove material from the outer layer 4 of the band 1.

[0204] Similarly, the installation 40 includes a second positioning system 42' which carries the second cutting tool 2', preferably at the end of a second robotic arm 44', and which allows the second cutting tool 2' to be positioned and moved relative to the frame 30, and more particularly relative to the main axis Z20, so as to make the second cutting tool 2' follow a second cutting path T2_2, distinct from the first cutting path T2_1, while the support 20 drives the band 1 in rotation R20, so as to remove material from the outer layer 4 of the band 1.

[0205] As mentioned above, the first and / or second positioning system 42, 42', and more particularly one and / or the other of the first and second robotic arms 44, 44', may include a pneumatic cylinder to radially clamp the cutting tool 2, 2' corresponding against wall 3 of bandage 1, and where appropriate to servo said cutting tool in radial force.

[0206] Each positioning system 42, 42' will preferably be provided with a sharpening system 45 to sharpen the cutting edge of the cylindrical knife 25, 25' mounted on the robotic arm 44, 44', as well as a chute 46, 46' to guide and facilitate the evacuation of chips or strips of material which are detached from the outer layer of the bandage 4 by the corresponding cutting tool 2, 2'.

[0207] Installation 40 also includes a control unit 51 allowing for the automatic control of installation 40.

[0208] Said control unit 51 includes a pilot unit 52 arranged to pilot the drive system 41 in order to implement the rotation R20 of the support 20 and to pilot and coordinate the first and second positioning systems 42, 42' in order to execute the first and second cutting trajectories T2_l, T2_2.

[0209] Advantageously, the control unit 52 allows the two cutting tools 2, 2' to be implemented simultaneously, and therefore the two cutting trajectories T2_l, T2_2 to be executed at least in part, or even in full, in time masked from each other, with, where appropriate, a slight advance given to the first cutting trajectory T2_l, as explained above.

[0210] The control unit 51 also includes a bandage analysis system 53 which makes it possible to identify, for example by means of an optical detection device 50 which may include a profilometer, a laser rangefinder, and / or a camera associated with image processing, the radial envelope distance D0_ply, the radial groove bottom reference DO groove, and / or the orientation A6 of the reinforcing wires, as explained above.

[0211] The control unit 51 further includes a cutting trajectory adaptation unit 54, which is arranged to define the first cutting trajectory T2_l and the second cutting trajectory T2_2, and in particular to ensure that the combination of said cutting trajectories, and more preferably each of said cutting trajectories T2_l, T2_2, makes it possible to remove material, in one or more zones of the outer layer 4, here more particularly each in the hemisphere Hl, H2 which is assigned to it, up to a depth which is located between the bottom 61B of the grooves 61 and the reinforcing layer 5.

[0212] In particular, the cutting path adaptation unit 54 is capable of defining a first and / or a second cutting path T2_l which presses the corresponding cutting tool 2, 2' against the reinforcing layer 5, 5', to slide said cutting tool 2, 2' into contact with the reinforcing wires 6, 6', and to include, if necessary, a centrifugal radial offset Delta_T2 to radially retract the cutting tool 2, 2' concerned in the portions of one and / or the other of the first and second cutting paths T2_l, T2_2 in which the reinforcing wires 6, 6' are in the opposite direction to the action of the cutting tool 2, 2', and more particularly in which the circumferential component Aô circ of the direction vector along which the reinforcing wires 6, 6' extend is of opposite sign to the circumferential component V2_circ of the velocity vector V2 along which the cutting tool 2, 2' moves relative to the wall 3 of the bandage,and therefore, in particular, in relation to the corresponding reinforcement layer 5, 5'.

[0213] The control unit 52, the bandage analysis system 53 and the cutting sequence adaptation unit 54 will preferably be electronic or computer-based, and will allow for the automatic execution of the bandage analysis, cutting trajectory adaptation, and coordinated execution of the cutting trajectories steps.

[0214] The control unit 52, the band analysis system 53 and the cutting sequence adaptation unit 54 can advantageously be grouped within the control unit 51, which is for example formed by a computer or an industrial programmable logic controller.

[0215] Of course, the invention is by no means limited to the variant embodiments described above, the person skilled in the art being able in particular to isolate or freely combine one or the other of the aforementioned characteristics, or to substitute equivalents for them.

[0216] In particular, the provisions applicable to machining under groove bottoms 61B, and more specifically with the use of a dummy interpolation line as described in scenario 7, could potentially be applied to machining of the band 1 that would employ a single cutting tool 2 rather than two cutting tools 2, 2', which single cutting tool 2 would process the entire width of said band 1, either in one pass covering both hemispheres H1, H2, or in two successive passes, each covering, from preference from trench 27 dug in the equatorial zone, a distinct hemisphere H1, H2.

Claims

CLAIMS 1. Method for machining a tire (1), said tire (1) having a wall (3) which comprises on the one hand at least one outer layer (4) based on elastomer, which has been shaped to have sculpture blocks (60) separated by grooves (61), and on the other hand at least one reinforcing ply (5) which is located under said outer layer (4) and which contains a plurality of reinforcing threads (6), said method comprising a step of removing material during which: - by means of a rotating support (20) having an axis of rotation called the “main axis” (Z20), the bandage (1) is driven in rotation (R20) on itself, around said main axis (Z20), in a chosen direction of rotation (R20+, R20-), and - while the bandage (1) is rotating (R20) in the chosen direction of rotation (R20+, R20-), at least two cutting tools (2, 2') are used which act simultaneously against the outer layer (4) to remove material therefrom, namely at least one first cutting tool (2) which is carried by a first positioning system (42) making it possible to position and move said first cutting tool (2) relative to the main axis (Z20), so as to make the first cutting tool (2) follow a first cutting path (T2_l), and at least one second cutting tool (2') which is carried by a second positioning system (42') making it possible to position and move said second cutting tool (2') relative to the main axis (Z20), so as to make the second cutting tool (2') follow a second cutting path (T2_2) distinct from the first cutting path (T2_l), said first and second cutting paths (T2_l,T2_2) being defined so that they allow material to be removed, in one or more areas of the external layer (4), up to a depth which is located between the bottom (61B) of the grooves (61) and the reinforcing ply (5)., 2. Method according to claim 1 characterized in that, the bandage (1) being axially divided into a first hemisphere (Hl) and a second hemisphere (H2) each located on a different side of the equatorial plane (P_EQ) of the bandage which is normal to the main axis (Z20) and passes through the middle of the axial range (Wl) occupied by the bandage (1), the first cutting tool (2) is assigned to the removal of material in the first hemisphere (Hl) of the bandage (1) while the second cutting tool (2') is assigned to the removal of material in the second hemisphere (H2) of the bandage (1).

3. Method according to claim 2 characterized in that the first cutting path (T2_l) is executed by bringing the first cutting tool (2) into contact with the reinforcing ply (5) then axially moving the first cutting tool (2) so as to slide the first cutting tool (2) into contact with the reinforcing ply (5) along the reinforcing wires (6), in at least a part or even the whole of the first hemisphere (Hl), and in that the second cutting path (T2_2) has, at least on a part of the second hemisphere (H2), a centrifugal radial offset (Delta_T2) relative to the first cutting path (T2_l), so as to preserve a certain residual excess thickness (Delta_4) of external layer (4) in the second hemisphere (H2) relative to the first hemisphere (Hl).

4. Method according to claim 2 or 3 characterized in that the first positioning system (42) forms a master positioning system which executes a first cutting trajectory (T2_l) according to which it axially moves the first cutting tool (2) from the equatorial plane (P_EQ) by sliding said first cutting tool (2) in contact with the reinforcing ply (5), along the reinforcing wires (6), in that the second positioning system (42') forms a slave positioning system within which the execution of the second cutting trajectory (T2_2) is delayed in time, according to which said second positioning system (42') axially moves the second cutting tool (2') from the equatorial plane (P_EQ), relative to the execution of the first cutting trajectory (T2_l), in that a crossing by the first cutting tool (2) of a first edge (5 1) of the reinforcing ply (5) in the first hemisphere is detected (Hl),and in that the second positioning system (42') is controlled so as to introduce into the second cutting path (T2_2) a centrifugal radial offset (Delta_T2) allowing the second cutting tool (2') to pass radially away from the reinforcing ply (5) when said second cutting tool (2') passes, in the second hemisphere (H2), through an abscissa which is the mirror image, relative to the equatorial plane (P_EQ), of the abscissa of the first edge (5 1) crossed by the first cutting tool (2)., 5. Method according to claim 4 characterized in that the axial movement of the second cutting tool (2') is triggered in the second hemisphere (H2) along the second cutting path (T2_2) when the first cutting tool (2) crosses, in the first hemisphere (Hl), a predetermined axial abscissa threshold away from the equatorial plane (P_EQ), or at the end of a predetermined time delay from the triggering of the axial movement of the first cutting tool (2) along the first cutting path (T2_l).

6. Method according to one of claims 2 to 5, characterized in that the first cutting path (T2_l) is executed by bringing the first cutting tool (2) into contact with the reinforcing ply (5) and then controlling the first cutting tool (2) in radial force while the first cutting tool (2) is moved axially, so as to slide the first cutting tool (2) into contact with the reinforcing ply (5), along the reinforcing wires (6), in the first hemisphere (Hl).

7. Method according to claim 6 and one of claims 4 or 5, characterized in that, during the execution of the first cutting path (T2_l), radial positions are measured which are successively adopted by the first cutting tool (2) controlled by radial force, along the first cutting path (T2_l) in contact with the reinforcing ply (5), and the second cutting tool (2') is controlled in radial position, from the measured radial positions of the first cutting tool (2), so as to be able to introduce a centrifugal radial offset (Delta_T2) in the second cutting path (T2_2) if, in the first hemisphere (Hl), a variation in the radial position of the first cutting tool (2) is detected which is representative of the axial crossing, by the first cutting tool (2), of an edge (5 1) of the reinforcing ply (5).

8. Method according to one of claims 2 to 7, characterized in that it comprises a preliminary step of analyzing the bandage during which the radial distance called "envelope radial distance" (D0_ply) is evaluated at which the radially external limit of the reinforcing threads (6) of the reinforcing ply (5) which is located immediately under the external layer (4) is located, relative to the main axis (Z20), in the absence of radial stress exerted on the wall (3) by the cutting tools (2, 2'), then a step of defining the trajectory cutting during which the first cutting path (T2_l), and preferably also the second cutting path (T2_2), is defined from the radial envelope distance, by fixing the radial position of the starting point (Kl) of the first cutting path (T2_l), and preferably also the radial position of the starting point (K2) of the second cutting path (T2_2), at a radial distance from the main axis (Z20) which is less than the radial envelope distance (D0_ply) by a non-zero value called "nominal deflection value" (D bend), said nominal deflection value (D bend) preferably being between 1 mm and 5 mm, more preferably between 2 mm and 5 mm, for example equal to 3 mm.

9. Method according to one of claims 1 or 2, characterized in that it comprises a preliminary step of analyzing the bandage during which the radial distance, called the "radial groove bottom reference" (DO groove), at which the bottom (61B) of at least one of the grooves (61) is located relative to the main axis (Z20), in the absence of radial stress exerted on the wall (3) by the cutting tools (2, 2'), is evaluated, then a step of defining the cutting trajectory, during which the first cutting trajectory (T2_l), and preferably also the second cutting trajectory (T2_2), is defined from the radial groove bottom reference (DO groove), by choosing a scenario from: - “scenario 5”: the starting point Kl of the first cutting path T2_l is fixed at a radial distance from the main axis Z20 which is less than the radial reference of the groove bottom (DO groove), by a chosen offset value (D_in) which is non-zero, an offset value which can be for example between 1 mm and 3 mm, and a first straight cutting path (T2_l) is opted for, the path of which forms, from the starting point (Kl), a straight line parallel to the main axis (Z20); - “scenario 6”: the starting point (Kl) of the first cutting path (T2_l) is fixed at a radial distance from the main axis (Z20) which is less than the radial groove bottom reference (DO groove), by a chosen offset value (D_in) which is non-zero, an offset value which can be for example between 1 mm and 3 mm, and a first curved cutting path (T2_l) is opted for, having a predetermined curved path which, in a radial plane containing the main axis (Z20), has a concave shape relative to the main axis (Z20); - “scenario 7”: we determine a fictitious curved interpolation line which passes through the funds (61B) respective of several grooves (61), preferably by the bottoms (61B) of all the grooves distributed axially in the zone of the external layer (4) concerned by the cutting path (T2_l, T2_2) considered, and one opts for a first curved cutting path (T2_l) which is parallel to the fictitious interpolation curved line, and closer to the main axis (Z20) than said fictitious interpolation curve by a chosen offset value (D_in) which is non-zero, an offset value which can be for example between 1 mm and 3 mm.

10. Method according to one of the preceding claims, characterized in that the first cutting tool (2) and the second cutting tool (2') are distant from each other, in azimuth around the main axis (Z20), by at least 30 degrees, preferably by at least 90 degrees, or even by at least 120 degrees, and for example by 180 degrees + / - 20 degrees.

11. Method according to one of the preceding claims, characterized in that the first cutting tool (2) and the second cutting tool (2') are formed respectively by a first cylindrical knife (25) and a second cylindrical knife (25'), the circular edges (25 A, 25' A) of which form the cutting edges and are oriented so as to engage the wall (3) in opposition to the direction of rotation (R20+, R20-) chosen.

12. Method according to one of the preceding claims, characterized in that it comprises, prior to the material removal step during which the first and second cutting tools (2, 2') act simultaneously, a trench digging step, during which the first cutting tool (2) is axially positioned at an axial abscissa included in an axial range which, on the one hand, represents less than 35% of the axial range (W1) covered by the bandage (1), preferably less than 30% of the axial range (W1) covered by the bandage (1), or even less than 25%, less than 20%, less than 15% or even less than 10% of the axial range (W1) covered by the bandage (1), and which, on the other hand, contains the equatorial plane (P_EQ) of the bandage (1), more preferably the first cutting tool (2) is axially positioned at the axial abscissa of the equatorial plane (P_EQ), then, while the bandage (1) is rotated (R20) around the main axis (Z20),the first cutting tool (2) is engaged in the internal layer (4), according to a centripetal radial penetration movement, so as to dig a circumferential trench (27) located at the abscissa, chosen axial, and in that the starting point (Kl) of the first cutting path (T2_l) followed by the first cutting tool (2) and the starting point (K2) of the second cutting path (T2_2) followed by the second cutting tool (2') are both located inside said trench (27).

13. Method according to one of the preceding claims, characterized in that, during the braking phases aimed at slowing the rotation speed of the support (20), energy is recovered by means of a converter, such as an alternator, coupled to said support (20).

14. Installation (40) for machining a bandage (1), said bandage (1) having a wall (3) which comprises on the one hand at least one external layer (4) based on elastomer, which has been shaped to present sculpture blocks (60) separated by grooves (61), and on the other hand at least one reinforcing ply (5) which is located under said external layer (4) and which contains a plurality of reinforcing threads (6), said installation comprising: - a rotary support (20) which is arranged to receive the bandage (1), which rotary support (20) is mounted in rotation on a frame (30) around a main axis (Z20), and associated with a drive system (41) which makes it possible to drive said rotary support (20), and therefore the bandage (1), in rotation (R20) on itself around said main axis (Z20), in a determined direction of rotation (R20+, R20-), - a first cutting tool (2), preferably formed by a first cylindrical knife (25), - a second cutting tool (2'), distinct from the first cutting tool (2), preferably formed by a second cylindrical knife (25'), - a first positioning system (42) which carries the first cutting tool (2) and which makes it possible to position and move said first cutting tool (2) relative to the frame (30) and relative to the main axis (Z20), so as to make the first cutting tool (2) follow a first cutting path (T2_l) while the support (20) drives the bandage (1) in rotation (R20), so as to remove material from the external layer (4) of the bandage (1), - a second positioning system (42') which carries the second cutting tool (2') and which makes it possible to position and move said second cutting tool (2') relative to the frame (30) and relative to the main axis (Z20), so as to make the second cutting tool (2') follow a second cutting path (T2_2), distinct from the first cutting path (T2_l), while the support (20) drives the bandage (1) in rotation (R20), so as to remove material from the external layer (4) of the bandage (1), - a control unit (51) for automatically controlling the installation (40), said control unit (51) comprising: - a control unit (52) arranged to control the drive system (41) in order to implement the rotation (R20) of the support (20) and to control and coordinate the first and second positioning systems (42, 42'), said control unit (52) making it possible to simultaneously implement the two cutting tools (2, 2'), and thus to execute the two cutting trajectories (T2_l, T2_2) at least partly in masked time with respect to each other, as well as: - a unit (54) for adapting the cutting paths, which is arranged to define the first cutting path (T2_l) and the second cutting path (T2_2), ensuring that the combination of said cutting paths (T2_l, T2_2), and more preferably each of said cutting paths (T2_l, T2_2), makes it possible to remove material, in one or more zones of the external layer (4), up to a depth which is located between the bottom (61B) of the grooves (61) and the reinforcing ply (5).

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