WO2023083987A1

WO2023083987A1 - Method for cutting a three-dimensional fabric comprising two sheets of fabric connected to one another by stays

Info

Publication number: WO2023083987A1
Application number: PCT/EP2022/081530
Authority: WO
Inventors: Clément NAGODE; Thomas SIMONELLI; Magaly BROUSSEAU
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2021-11-15
Filing date: 2022-11-10
Publication date: 2023-05-19
Also published as: FR3129158A1; FR3129158B1

Abstract

The invention relates to a method for cutting a "three-dimensional" fabric (1) comprising a lower sheet (2) and an upper sheet (3) connected to one another by stays (4), the method implementing a cutting tool (10) that first comprises a penetrating tip (13) which separates the sheets (2, 3) from one another while passing between the stays (4) and then a stabilizing spacer (14) which keeps the sheets (2, 3) separated, and the stays (4) under tension, while a cutting blade (15) cuts at least one of the sheets (2, 3).

Description

METHOD FOR CUTTING A THREE-DIMENSIONAL FABRIC COMPRISING TWO LAYERS OF FABRIC CONNECTED TO EACH OTHER BY STAYS

The present invention relates to the field of tissue cutting.

[0002] It is known, in particular from patent FR-3,088,238 filed by the applicant, to implement a so-called "three-dimensional" fabric which comprises, superposed in a direction called "stack direction", a first ply of fabric forming a lower ply, a second ply of fabric forming an upper ply which extends parallel to said lower ply, and a network of reinforcing threads called "stays" which are interposed between the lower ply and the upper ply and which each connect the lower ply to the upper ply in order to allow the upper ply and the lower ply to move away from each other in the stacking direction, within the limit of a distance of maximum spacing which is determined by the length of the stays, and while remaining captive to each other.

[0003] Such a three-dimensional fabric can in particular be used for the manufacture of pneumatic tires for vehicle wheels, or else in various other applications.

[0004] However, a difficulty lies in the cutting of such a three-dimensional fabric. Indeed, when the three-dimensional fabric is flat, the stays are crushed in relative disorder between the lower and upper layers, so that it is not possible to make a cut line in the thickness of the three-dimensional fabric without randomly cut one or more stay cables.

[0005] One solution may consist in manually separating the lower and upper plies to carefully make a cut using a cutting tool, avoiding cutting a stay. However, such a manual operation remains relatively delicate, and is hardly suited to industrial-scale exploitation of the three-dimensional fabric.

[0006] The objects assigned to the invention therefore aim to remedy the aforementioned drawbacks and to propose a new cutting process which guarantees precise, reliable and efficient cutting of a three-dimensional fabric. The objects assigned to the invention are achieved by means of a process for cutting a fabric called "three-dimensional fabric" which comprises, superposed in a direction called "stack direction", i) a first ply of fabric, called "lower ply", which extends in length along a first direction called "warp direction" which is perpendicular to the stacking direction, and in width along a direction called "weft direction" which is perpendicular in the warp direction and in the stacking direction, ii) a second ply of fabric, called "upper ply", which is distinct from the lower ply and which extends parallel to said lower ply, and iii) a network wires called "stays" which are interposed in the space called "connection space" between the lower ply and the upper ply, and which each connect the lower ply to the upper ply in order to allow the upper ply and the lower ply to deviate at a distance from each other in the stacking direction, within the limit of a maximum separation distance which is determined by the length of the stays, while remaining captive to one of the other, said method being characterized in that it comprises:

- a step (a) of opening, during which a cutting tool is introduced into the connecting space, between two neighboring stays, and in a direction called the "direction of introduction" which is perpendicular to the direction d stack, said cutting tool comprising a first sole, called "lower sole", intended to slide in contact with the face of the lower ply which is oriented on the side of the connecting space as well as a second sole, called sole "upper", intended to slide in contact with the face of the upper ply which is oriented on the side of the connecting space, said lower and upper flanges forming as a whole, successively along the direction of introduction, while first i) a penetration tip, along which the height which separates the bottom flange from the top flange, considered according to the stacking direction, increases progressively, so that said penetration tip can progressively move apart, as as the cutting tool progresses in the direction of insertion, the upper ply and the lower ply one from the other, according to the direction of stacking, until placing said lower and upper ply in a configuration called "fully open configuration" which corresponds to the maximum spacing distance authorized by the stays, then ii) a stabilizing spacer whose height corresponds to the maximum spacing distance authorized by the stays, in order to maintain the three-dimensional fabric in fully open configuration,

- a step (b) of cutting, during which at least one of the lower and upper layers is cut, without cutting stays, by means of a cutting blade which is associated with the corresponding sole, at the level of the stabilization strut.

[0008] Advantageously, the method according to the invention makes it possible to position, in a reproducible manner, the cutting tool between two rows of stays, to gradually change the three-dimensional fabric from a loose or even flattened configuration to a fully open configuration, simply because of the relative movement of the penetration tip with respect to the three-dimensional fabric along the direction of insertion, which will make it possible to tension the stays to align said stays all substantially perpendicular to the lower and upper plies, and to maintain said stays in tension, before the passage of the cutting blade and until after the passage of the cutting blade, so that the trajectory of the cutting blade never crosses the route of a stay, and that the cutting operation therefore preserves the integrity of said stays.

[0009] Other objects, characteristics and advantages of the invention will appear in more detail on reading the following description, as well as with the aid of the appended drawings, provided for purely illustrative and non-limiting purposes, among which :

[0010] Figure 1 illustrates, in a perspective view, a piece of three-dimensional fabric according to the invention, in fully open configuration.

Figure 2 is a side view of the three-dimensional fabric of Figure 1, in a projection plane containing the stack direction and the warp direction.

[0012] Figures 3 A and 3B illustrate, respectively in a perspective view and a front projection view in a plane normal to the direction of insertion, a cutting tool according to the invention, designed to make a cut of the top layer only.

Figures 4A, 4B, 4C and 4D are perspective views of the successive phases of a transverse cutting operation of the three-dimensional fabric of Figures 1 and 2 by the tool of Figures 3A and 3B, in a direction of introduction which is transverse, here perpendicular, to the warp direction, and therefore parallel to the weft direction. [0014] Figures 5 A and 5B illustrate, respectively in a perspective view and a front projection view in a plane normal to the direction of insertion, a variant of the cutting tool of Figures 3 A, 3B which has a bulge to widen the bearing surface of the upper sole, in the part forming the stabilizing spacer.

Figures 6A and 6B illustrate, respectively in a perspective view and a front projection view in a plane normal to the direction of insertion, another variant of the cutting tool of Figures 3A, 3B whose section widens progressively from the lower flange to the upper flange so that the upper flange is wider than the lower flange in the part forming the stabilizing spacer.

[0016] Figure 7 illustrates, in a perspective view, a variant of three-dimensional fabric which has, in its width, empty spaces of stays called "longitudinal corridors" which allow the insertion of cutting tools to make a cut longitudinally, in a direction of introduction which this time is parallel to the warp direction.

[0017] Figures 8A and 8B illustrate, respectively in a side view in a plane containing the insertion direction and the stacking direction and in a front projection view in a plane normal to the insertion direction, a variant of a cutting tool according to the invention which makes it possible to carry out a simultaneous cutting of the lower ply and of the upper ply, more particularly a longitudinal cut according to an insertion direction parallel to the warp direction, for example when said cutting tool is inserted in a longitudinal corridor of the three-dimensional fabric of Figure 7.

Figures 9A and 9B illustrate, respectively in a side view in a plane containing the insertion direction and the stacking direction and in a top projection view in a plane normal to the stacking direction, a variant of the cutting tool of FIGS. 8A and 8B, the flanges of which have a flattened shape, and therefore a low grip in height, to facilitate the path of the penetration tip between the roots of the stays, as close as possible to the lower layers and upper of the three-dimensional fabric.

The present invention relates to a method for cutting a fabric 1 called "three-dimensional fabric" 1. As can be seen in particular in FIGS. 1, 2 and 7, such a three-dimensional fabric 1 comprises, superposed in a direction called the “stack direction” DZ: i) a first layer 2 of fabric, called the “ lower ply" 2, which extends in length along a first direction called the "warp direction" DX which is perpendicular to the stacking direction, and in width along a direction called the "weft direction" DY which is perpendicular to the warp direction DX and stacking direction DZ, ii) a second ply 3 of fabric, called the "upper ply" 3, which is separate from the lower ply 2 and which extends parallel to said lower ply 2, and iii) a network of wires 4 called "stays" 4 which are interposed in the space called "connection space" 5 between the lower ply 2 and the upper ply 3 and which each connect the lower ply 2 to the upper ply 3 in order to allow the upper ply 3 and the lower ply 2 to deviate at a distance Tune from each other in the stacking direction DZ, within the limit of a maximum separation distance H5_max which is determined by the length of the shrouds 4, and while remaining captive Tune each other.

The lower 2 and upper 3 sheets are preferably each made of a woven fabric, the warp yarns of which are oriented in the warp direction DX and the weft yarns are oriented in the weft direction DY.

The stays 4, which keep the lower ply 2 and the upper ply 3 attached Tune to each other, are made of a flexible but substantially inextensible material, in order to allow the three-dimensional fabric 1 to alternately adopt a flattened configuration, in which the upper ply 3 is close to the lower ply 2, and the stays 4 sandwiched and laid between said layers 2, 3, and an open configuration, in which the stays are deployed and stretched to accompany the upper ply 3 which moves away from the lower ply 2 in the stacking direction DZ until reaching the planned maximum separation distance H5_max, at which said stays 4 stop the separation of the layers 2, 3 and oppose any mutual separation additional said lower 2 and upper 3 plies in the stacking direction DZ. For information, the stays 4 may be made of polyamide, polyester, elastane, aramid, or a mixture of these materials.

[0024] The length of the stays 4, and consequently the maximum spacing distance H5_max may be between 40 mm and 70 mm, more preferably between 45 mm and 65 mm, or even between 55 mm and 65 mm.

[0025] Preferably, the lower ply 2 and the upper ply 3 overlap exactly, in projection in a plane normal to the stacking direction DZ, and for this purpose both have the same length in the chain direction DX on the one hand, and the same width along the frame direction DY on the other hand.

According to the invention, the method firstly comprises a step (a) of opening, which corresponds for example to FIGS. 4A and 4B, during which a cutting tool 10 is introduced into the space of link 5, between two neighboring stays 4, and in a direction called the "insertion direction" D10 which is perpendicular to the stacking direction DZ, said cutting tool 10 comprising a first flange 11, called the "lower flange" 11, intended to slide in contact with the face of the lower ply 2 which is oriented on the side of the connecting space 5 as well as a second sole 12, called "upper" sole 12, intended to slide in contact with the face of the upper ply 3 which is oriented on the side of the connecting space 5.

As can be seen in particular in FIGS. 3A, 5A, 6A, 8A and 9A, said lower 11 and upper 12 flanges form as a whole, successively along the insertion direction D10, first of all i ) a penetration tip 13, along which the height H13 which separates the lower flange 11 from the upper flange 12, considered in the stacking direction DZ, increases progressively, so that said penetration tip 13 can spread progressively, as the cutting tool 10 progresses in the insertion direction D10, the upper ply 3 and the lower ply 2 move apart, in the stacking direction DZ, as illustrated in FIG. 4B, until said lower 2 and upper 3 layers are placed in a so-called “fully open configuration” configuration which corresponds to the maximum separation distance H5_max authorized by the stays 4, then ii) a stabilization spacer 14 whose height H14 corresponds to the maximum separation distance H5_max authorized by the stays 4, in order to maintain the three-dimensional fabric 1 in the fully open configuration, as is the case in FIG. 4C.

[0028] Step (a) of opening thus comprises a separation phase, during which the cutting tool 10 spreads the plies 2, 3 in order to put the stays 4 under tension, then a stabilization phase during which the spacer 14 keeps the layers 2, 3 apart and the stays 4 in tension.

[0029] At the level of the stabilizing spacer 14, the lower 11 and upper 12 flanges preferably form flat surfaces parallel to each other, normal to the stacking direction DZ. Said soles 11, 12 are therefore capable of maintaining, at least locally, the layers 2, 3 parallel to each other, at a distance from each other which is equal to the maximum spacing distance H5_max , and each of said plies 2, 3 substantially in a plane normal to the stacking direction DZ.

It will be noted that, for simple convenience of representation and for better readability, the views 4A and 4B intentionally show the three-dimensional fabric 1 in a fully open configuration, whereas, in practice, said three-dimensional fabric 1 is, as long as it has not been moved aside by the penetration tip 13 and that it is not effectively supported and tensioned by the cutting tool 10, in a loose state, the stays 4 being more or less collapsed.

[0031] Advantageously, the opening effect provided by the insertion of the cutting tool 10 between the lower 2 and upper 3 plies allows said plies 2, 3 to exert traction on the stays 4, and therefore to straightening and tensioning the stays 4, according to the direction of longitudinal extension of the said stays 4, then to maintain the said stays 4 in tension as long as the stabilization spacer 14 prevents the said lower 2 and upper 3 plies from approaching the one from the other under the tensile force exerted on said plies 2, 3, in reaction, by the stays 4.

The three-dimensional fabric 1 is thus advantageously opened by wedge effect, thanks to the penetration tip 13 which rests on the lower ply 2, by means of the lower sole 11, to separate the lower ply 2 from the upper ply 3, against which the upper flange 12 simultaneously bears to push back said upper ply 3. At the end of this opening phase, said three-dimensional fabric 1 is stabilized in a fully open configuration, which is stiffened by the stabilization spacer 14 that includes the cutting tool 10.

[0033] The three-dimensional fabric 1 being thus stretched in the direction of stacking DZ and stiffened, and the stays 4 being consequently freed from the path of the cutting tool 10 and ordered, here substantially aligned in rows with each other. compared to the others, it is possible to easily cut the layer(s) 2, 3 referred to, without risking accidentally cutting a stay 4.

According to the invention, the method therefore then comprises, after step (a) of opening, a step (b) of cutting, during which at least one of the lower layers 2 and upper 3, without cutting stays 4, by means of a cutting blade 15 which is associated with the corresponding sole 11, 12, at the level of the stabilizing spacer 14, as illustrated for example in FIG. 4C.

[0035] Advantageously, it suffices for this to continue the movement of the cutting tool 10 with respect to the three-dimensional fabric 1 along the direction of introduction D10, which thus defines the orientation of the cutting line LC2, LC3 according to which the sheet 2, 3 concerned is cut (FIGS. 4C, 4D), or if necessary the two cutting lines LC2, LC3 along which each of the two sheets 2, 3 is respectively cut (FIG. 7).

By preserving the stays 4, on each side of the cut line LC2, LC3, the mechanical properties and the homogeneity of the structure of the three-dimensional fabric 1 are advantageously preserved.

The cutting blade 15 may have any suitable shape. Preferably, said cutting blade 15 may have a concave curved shape, like a sickle, as can be seen in particular in FIGS. 3A, 5A, 6A, 8A and 9A. According to a particularly simple and compact arrangement, said cutting blade 15 can be fixed directly on the sole 11, 12 concerned.

[0038] In practice, the stacking direction DZ will preferably be vertical, so that the sheets 2, 3 will form horizontal surfaces when they are subjected to the cutting action, this cutting action which will take place itself. even following an insertion direction D10 horizontal. In accordance with the chosen naming convention, the lower layer 2 will then preferably be positioned below the upper layer 3, that is to say at an altitude lower than that of the upper layer 3.

[0039] Preferably, as is particularly visible in Figures 3A, 5A, 6A, 8A and 8B, 9A and 9B, the penetration tip 13 of the cutting tool 10 has, in projection in a plane normal to the stacking direction DZ, a first bevel 16 allowing the cutting tool 10 to clear a passage between two neighboring stays 4, and, in projection in a plane containing the direction of introduction D10 and the direction of stack DZ, a second bevel 17 which allows the penetration tip 13 to separate the lower 2 and upper 3 layers from each other until reaching the fully open configuration.

[0040] Advantageously, the same penetration tip 13 thus ensures the clearance of the passage for the cutting tool 10 in the two directions transverse to the direction of penetration D10, namely in the width of the cutting tool 10 thanks to the first bevel 16, and in the height of the cutting tool 10 thanks to the second bevel 17.

The bevels 16, 17 may, without departing from the scope of the invention, form rectilinear ramps, and therefore appear in projection in the form of straight line segments arranged in broken lines, or else may form curved ramps, which follow curved lines.

The first and the second bevels 16, 17 can join and coexist at the front end of the flange(s) 11, 12 considered, to form a point, for example a point in the shape of a polyhedron as is the case in Figures 3A, 5A, 6A, or a rounded tip, as is the case in Figures 9A and 9B.

[0043] In all cases, the penetration tip 13 advantageously forms a stem which precedes the stabilization spacer 14 to separate the layers 2, 3 and the shrouds 4.

The variation in the height H13 of the penetration tip which is induced by the second bevel 17 will preferably represent at least 5%, preferably at least 10%, or even at least 30%, and optionally up to 100% (Case of Figures 3A, 5A, 6A) of the height H14 of the stabilizing spacer 14, and therefore of the maximum separation distance H5_max. Thus, the gradual increase in height provided by the penetration tip 13 will be sufficient to allow the penetration tip 13 to engage tissue. three-dimensional 1 unstretched then to bring said three-dimensional fabric 1, and more particularly the stays 4, under tension in the stacking direction DZ.

In the variants illustrated in Figures 3A, 5A and 6A, the variation in height of the penetration tip induced by the second bevel 17 is equal to the influence in height H12 of the upper flange 12, since said second bevel 17 is here carried exclusively by said upper flange 12.

In the variants illustrated in Figures 8A, 8B and 9A and 9B, the variation in height of the penetration tip induced by the second bevel is equal to the sum of the respective height grips H1, H12 of the lower flange 11 and the upper sole 12, since the second bevel 17 is distributed between these two soles 11, 12.

If one chooses to create a small variation in the height H13 of the penetration tip 13, for example representing 5% to 10% of the maximum spacing distance H14, soles 11 can be used for this purpose. , 12 relatively flat, that is to say having a small influence in height H1 1, H12 in the stacking direction DZ, as illustrated in Figures 9A and 9B.

[0048] Such relatively flat flanges 11, 12 will be particularly suitable for engaging said flanges 11, 12 as close as possible to the "roots" of the stays 4, that is to say closest to the place where said stays 4 emerge from the lower 2 and upper 3 layers respectively, in the connecting space 5, in the stacking direction DZ. This can be advantageous in order to be able to engage the cutting tool 10 between two rows of stays 4 which have a great length, and which thus tend, when they are not yet stretched, to be disorderly and to intersect in the central portion of the connecting space 5.

[0049] Indeed, to prevent such shrouds 4 from passing on the "wrong" side of the first bevel 16 and of the sole 11, 12, and therefore so that the penetration tip 13 does not become trapped and hindered by said stays 4 and does not destroy said stays 4 during its progression in the direction of introduction D10, it is desirable to position and keep the tips of the soles 11, 12 in the immediate vicinity of the layers 2, 3 and therefore of the roots of the stays 4, at a distance from the central part of the connecting space 5 (considered along the stacking direction DZ), limiting the influence in height H1 1, H12 of each flange 11, 12.

Preferably, as is clearly visible in Figures 1 and 2, the three-dimensional fabric 1 comprises a plurality of continuous reinforcing threads 20 which are oriented in the warp direction DX and arranged side by side, parallel to each other. to the others, according to a predetermined repetition pitch P20 in the frame direction DY.

[0051] Preferably, each reinforcing thread 20 then forms, along the warp direction DX, and as illustrated in FIG. 2, a slotted wave which comprises a succession of periods which each comprise a first segment 21 called "upper segment" 21, where the reinforcing thread 20 is interwoven with the upper ply 3, then a second segment 22 forming a so-called "descending" stay 4 which connects said upper segment 21, and therefore the upper ply 3, to the lower ply 2, then a third segment 23 called "lower segment" 23, where the reinforcing thread 20 is interwoven with the lower ply 2, then a fourth segment 24 forming a stay 4 called "upward" which connects said lower segment 23 , and therefore the lower layer 2, to the upper layer 3.

And so on, the fourth segment 24 forming the ascending stay 4 connects the lower segment 23 of the period concerned to the first segment, namely the upper segment 21, of the following period, etc.

Advantageously, the use of such reinforcing threads 20 which are uninterrupted over the entire length of the three-dimensional fabric 1, and which each pass alternately from the upper sheet 3 to the lower sheet 2 and then vice versa, simplifies the manufacture of the three-dimensional fabric , and guarantees a solid anchorage, and therefore great sturdiness, of the stays 4.

Preferably, the segments 21, 22, 23, 24, and therefore more particularly the corresponding guy wires 4, of the various reinforcing threads 20 which follow one another along the frame direction DY, are aligned in rows in said direction. of frame DY, so as to delimit within the connecting space 5, between each row of stays 4, transverse corridors 25 empty of stays and oriented in said direction of frame DY. According to a first possibility of implementation, which corresponds to Figures 4A to 4D, and which will be called "transverse cut", the direction of introduction D10 is transverse to the direction of chain DX, and more preferably perpendicular to the warp direction DX and therefore parallel to the weft direction DY.

The penetration tip 13 of the cutting tool 10 is then engaged in the space called "transverse corridor" 25 which is between on the one hand a row of descending stays 4, 22 distributed along the direction of frame DY and which correspond to the plurality of reinforcing threads 20, and on the other hand the row of ascending guys 4, 24 immediately following, as can be seen in FIG. 4B.

According to this first possibility of implementation, the lower flange 11 has no cutting blade 15 and is arranged so as to slide over the row of lower segments 23 which are integrated into the lower ply 2 plumb with the corridor transverse 25, without cutting said lower segments 23, while the upper flange 12 is provided with a cutting blade 15 which cuts the upper ply 3, in the space comprised between two successive rows of upper segments 21, and consequently without cut the reinforcing threads 20, as shown in Figures 4C and 4D.

[0058] Advantageously, the lower sole 11 is used here to retain the lower ply 2, and the lower segments 23 of the reinforcing threads 20, which form the floor of the transverse corridor 25, against the tensile stress exerted in the stacking direction DZ by tensioning the stays 4 and by the cutting operation, while the upper flange 12 stretches the upper ply 3 and cuts the latter in an interval where said upper ply 3 is devoid of reinforcement 20, and which here corresponds to the ceiling of the transverse corridor 25. This avoids any damage to the three-dimensional fabric 1, and in particular any tearing of the stay 4, during the cutting operation.

Preferably, the lower flange 11 will rest, in the stacking direction DZ, on the lower ply 2, and therefore on the corresponding lower segments 23, while the lower ply 2 and the lower segments 23 will rest themselves on an underlying rigid support, such as an anvil or table. The lower ply 2, and more generally the three-dimensional fabric 1, will thus be guided in a particularly precise and fluid, between the lower flange 11 and the underlying support, during the cutting operation.

Advantageously, the fact of making cuts in only one of the two sheets 2, 3 makes it possible to keep the three-dimensional fabric 1 in one piece, thanks to the sheet 2 intact, not cut, while increasing the capacity of said three-dimensional fabric 1 to conform to fit a curved surface, since the cut lines LC3 allow the different portions of the sheet 3 cut to move away freely from each other in order to accommodate an increase in length induced by the curvature of said surface.

According to a preferred possibility of arrangement of the cutting tool 10, the width W12 of the upper sole 12, considered perpendicular to the direction of insertion D10, is greater than the width W11 of the lower sole 11, as seen in Figures 5B and 6B.

[0062] Such an arrangement makes it possible to take into consideration the fact that the guys 4 are generally, even when they are placed under tension in the fully open configuration, not strictly perpendicular to the layers 2, 3, in particular because of the transitions between segments 21, 23 integrated into said plies 2, 3 and emerging segments 22, 24 forming the stays 4, so that said segments 21, 22, 23, 24 of the same reinforcing wire 20 do not exactly form an undulation in rectangular slots , but rather follow, along the warp direction DX, an undulation in trapezoidal crenellations, the small bases of which correspond to the segments 21, 23 integrated into the layers 2, 3, and the large bases correspond to the intervals, empty of reinforcing threads 20, which separate within the same ply 2, 3, and along the same reinforcing thread 20, two successive segments of the same nature integrated into said ply 2, 3 (that is to say two segments successive upper 21 of the same reinforcing thread 20, or respectively two successive lower segments 23 of the same reinforcing thread).

[0063] Indeed, the increased width W12 of the upper flange 12 thus makes it possible to maximize the bearing surface of the laying tool 10 which supports the upper ply 3 during the cutting operation, at the level of the large base. of the trapezium, that is to say, in the example used here, between two successive upper segments 21, at the level of the corridor ceiling transverse 25. This stabilizes the upper ply 3 even more effectively during the cutting operation.

[0064] The additional width W 12 of the upper flange 12 can be obtained by any suitable arrangement, for example by providing a local bulge or an added part 26 in extra thickness of the cutting tool 10 in the zone of the spacer stabilizer 14, as shown in Figures 5A and 5B, or even by providing a cutting tool 10 whose section is, in the area of the stabilizing spacer 14, flared so as to widen continuously , according to a predetermined opening angle A14, between the lower flange 11 and the upper flange 12, as can be seen in FIG. 6B.

According to a second possibility of implementation, which will be called “longitudinal cutting”, the direction of introduction D10 is, this time, parallel to the direction of the chain DX.

The penetration tip 13 of the cutting tool 10 is then engaged in the space called "longitudinal corridor" 27 which is between two immediately adjacent parallel reinforcing threads 20.

Preferably, according to this second possibility of implementation, the lower flange 11 and the upper flange 12 are each provided with a cutting blade 15, as shown in Figures 8A, 8B and 9A, in order to to simultaneously cut the lower ply 2 and the upper ply 3 along the warp direction DX, between the two reinforcing threads 20, as shown schematically by the cutting lines LC2, LC3 which appear in dotted lines in the figure 7.

[0068] Such a possibility of implementation will in particular make it possible to precisely debit a desired width of three-dimensional fabric 1.

The lines of cuts LC2, LC3 may possibly be located substantially at the center of the longitudinal corridor 27 along the frame direction DY, but not necessarily. Preferably, the cut lines LC2, LC3 will be located at a distance of between 2 mm and 4 mm from the last stay 4 belonging to the strip of three-dimensional fabric 1 that it is desired to keep, and this so that one can achieve cutting as close as possible to the stay 4 but while preserving a few warp threads intact between said stay 4 and the cutting line LC2, LC3, and therefore between said stay 4 and the edge of the strip thus cut, so as to prevent said stay 4, which is found closest to said edge of the strip, from separating from said strip when implementation of said band.

It will be noted that a widened longitudinal corridor 27 can be provided, by locally increasing the distance which separates, in the weft direction DY, the immediately neighboring reinforcing threads 20 which laterally delimit said longitudinal corridor 27, with respect to the distance which separates the other reinforcing threads 20 from each other, that is to say that it will be possible to increase locally, at the iteration of implantation of the reinforcing threads 20 which corresponds to the longitudinal corridor 27, the pitch P20 of distribution between the reinforcing threads 20, with respect to the "normal" pitch P20 of distribution which is used outside the longitudinal corridor 27, as can be seen in Figure 7.

[0071] A widened longitudinal corridor 27 will in fact facilitate the introduction and then the progression of the cutting tool 10 with respect to the three-dimensional fabric 1, and will considerably limit the risks of a stay 4 catching or a stay 4 by a sole 11, 12. It will also allow the use of relatively wide soles 11, 12, which will offer a large bearing surface to the layers 2, 3, and will thus ensure a particularly stable maintenance of the layers 2, 3 , especially during the cutting operation.

[0072] However, with a suitable cutting tool 10, in particular a cutting tool 10 whose soles 11, 12 have a small grip in height H11, H12 as described above, the three-dimensional fabric 1 can be cut along a “narrow” longitudinal corridor 27, that is to say the width of which corresponds for example to the “normal” distribution pitch P20, which is constant, of the stays 4 in the frame direction DY.

According to a particularly preferred variant of the second possibility of implementing the aforementioned method, two cutting tools 10 are simultaneously engaged in two separate parallel longitudinal corridors 27, so that the simultaneous cutting operation of the lower plies 2 and upper 3 in each of the two longitudinal corridors 27 makes it possible to subdivide the three-dimensional fabric 1 into a central strip 28, between the two longitudinal corridors 27, and two lateral strips 29, 30, as shown in Figure 7. Such a method, which simultaneously involves four soles 11, 12 and four corresponding cutting blades 15, makes it possible in particular to produce a central strip 28 of suitable width, for example adapted to the dimensions of the tire that said central strip 28 will equip, and eliminate the edges corresponding to the side bands 29, 30, in order to achieve a precise, clean and flawless delimitation of the central band 28.

Such a process can in particular be implemented downstream of a manufacturing station where a three-dimensional fabric 1 is produced continuously, over very long lengths, greater than a hundred meters or even a thousand meters. , in order to make a longitudinal cut, and therefore an adaptation in width of the three-dimensional fabric 1, on the fly, as said three-dimensional fabric comes out, in its raw state, from the manufacturing station.

According to one possibility of implementation, one could of course provide a three-dimensional raw fabric 1 of wide width, and simultaneously produce, continuously, several parallel central strips 28, distributed side by side in the width of the three-dimensional fabric

1 raw, by means of several cutting tools 10 acting in parallel with each other to cut the three-dimensional fabric 1 on the fly along as many cutting lines LC2, LC3 parallel to each other.

An example of cutting tool 10 particularly suitable for longitudinal cutting is shown schematically in Figures 8A and 8B.

According to this preferred example, the lower sole 11 and the upper sole 12 each have the shape of a ski provided with a curved spatula 31, and are abutted mirror-like by their respective spatulas 31 to form the penetration tip 13.

The presence of spatulas 31 arranged substantially symmetrically with respect to a plane of symmetry normal to the stacking direction DZ can in particular allow, if the influence in height H11, H12 of said spatulas, and therefore of the soles, is large enough, to place the top of the penetration tip 13 substantially at mid-height of the connecting space 5, and allows the two sheets 2, 3 to be distributed and to flow in a substantially symmetrical and homogeneous manner the along the cutting tool 10, each on a different side of the plane of symmetry, which avoids cutting irregularities between the lower ply

2 and the top layer 3. [0080] As such, the cutting tool 10 will preferably be mounted in height and in a fixed position, so that the lower 2 and upper 3 plies which scroll in contact with the soles 11, 12 are floating, i.e. that is to say that are not pressed by the cutting tool 10 against any support such as a table or an anvil, and that their trajectory is not constrained by such a support which would be placed opposite the soles 11, 12. Said layers 2, 3 therefore circulate freely on each of the opposite faces of said cutting tool 10, such that these faces are materialized by a sole 11, 12.

The spatulas 31 can advantageously form the double bevel 16, 17 mentioned above. In addition, the curved profile of the spatulas 31 will facilitate gentle introduction and progression of the penetration tip 3, and more generally of the cutting tool 10, within the three-dimensional tissue 1.

The alternative embodiment illustrated in FIGS. 9A and 9B presents a cutting tool 10 whose soles 11, 12 have “quasi-flat” spatulas 31 and which therefore advantageously have a small grip in height H11, H12. Such a variant will be particularly suitable for cutting a three-dimensional fabric 1 whose stays have a great length, typically of the order of 55 mm to 65 mm, and whose longitudinal corridors 27 have a small width (considered at the root guy wires 4 formed by two neighboring reinforcing threads 20), typically between 15 mm and 25 mm, in particular of the order of 20 mm.

[0083] Advantageously, the implementation of relatively narrow longitudinal corridors 27 will make it possible to maximize the useful width of the central strip 28, and therefore to reduce the falls represented by the side strips 29, 30.

[0084] Furthermore, preferably, and in particular in the case where a longitudinal cut is made, the cutting movement is generated by moving the three-dimensional fabric 1, along the direction of introduction DI 0, with respect to the cutting tool 10 which is held fixed.

Such an option makes it possible in particular to manage a continuous flow of three-dimensional fabric 1, in the case of a longitudinal cut.

[0086] The three-dimensional fabric 1, and more particularly the central strip 28 and the side strips 29, 30 which come from it, can be towed by motorized reels located downstream of the cutting tool 10 and on which said strips 28, 29, 30 are wound, as they are cut.

Of course, the invention is not limited solely to the variant embodiments described in the foregoing, the person skilled in the art being in particular able to isolate or freely combine one or the other of the aforementioned characteristics or to substitute their equivalents.

Claims

1. A method of cutting a fabric called "three-dimensional fabric" (1) which comprises, superimposed in a direction called "stack direction" (DZ), i) a first sheet (2) of fabric, called "sheet bottom" (2), which extends in length in a first direction called "warp direction" (DX) which is perpendicular to the stacking direction (DZ), and in width in a direction called "weft direction" (DY) which is perpendicular to the warp direction (DX) and to the stacking direction (DZ), ii) a second ply (3) of fabric, called "upper ply" (3), which is distinct from the lower ply (2) and which extends parallel to said lower ply, and iii) a network of wires called "stays" (4) which are interposed in the space called "connection space" (5) between the ply lower layer (2) and the upper layer (3) and which each connect the lower layer (2) to the upper layer (3) in order to allow the upper layer (3) and the lower layer (2) to move apart away from each other in the stacking direction (DZ), within the limit of a maximum spacing distance (H5_max) which is determined by the length of the stays (4), while remaining captive l one from the other, said method being characterized in that it comprises:

- a step (a) of opening, during which a cutting tool (10) is introduced into the connecting space (5), between two neighboring stays (4), and in a direction called the "direction of introduction" (D10) which is perpendicular to the stacking direction (DZ), said cutting tool (10) comprising a first sole (11), called "lower sole" (11), intended to slide in contact with the face of the lower ply (2) which is oriented on the side of the connecting space (5) as well as a second sole (12), called "upper" sole (12), intended to slide in contact with the face of the upper ply (3) which is oriented on the side of the connecting space (5), said lower (11) and upper (12) flanges forming as a whole, successively along the direction of introduction (D10), while first i) a penetration point (13), along which the height (H13) which separates the lower flange (11) from the upper flange (12), considered according to the stacking direction (DZ), increases gradually, so that said penetrating tip (13) can progressively separate, as the cutting tool (10) progresses in the direction of insertion (D10), the upper ply (3) and the ply lower (2) of each other, according to the stacking direction (DZ), until said lower (2) and upper (3) layers are placed in a so-called “fully open configuration” configuration which corresponds to the maximum spacing distance (H5_max) authorized by the stay cables ( 4), then ii) a stabilizing spacer (14) whose height (H14) corresponds to the maximum spacing distance (H5_max) authorized by the stays (4), in order to maintain the three-dimensional fabric

(1) in fully open configuration,

- a step (b) of cutting, during which at least one of the lower layers is cut

(2) and upper (3), without cutting stays (4), by means of a cutting blade (15) which is associated with the corresponding sole (11, 12), at the level of the stabilizing spacer ( 14).

2. Method according to claim 1 characterized in that the penetration tip (13) of the cutting tool (10) has, in projection in a plane normal to the stacking direction (DZ), a first bevel (16 ) allowing the cutting tool (10) to clear a passage between two neighboring stays (4), and, in projection in a plane containing the direction of introduction (D10) and the direction of stacking (DZ), a second bevel (17) which allows the penetration tip (13) to separate the lower (2) and upper (3) layers from each other until reaching the fully open configuration.

3. Method according to claim 1 or 2 characterized in that the three-dimensional fabric (1) comprises a plurality of continuous reinforcing threads (20) which are oriented in the warp direction (DX) and arranged side by side, parallel to each other. to the others, according to a predetermined repetition pitch (P20) in the weft direction (DY), each reinforcing thread (20) forming, along the warp direction (DX), a slotted wave which comprises a succession of periods which each comprise a first segment (21) called "upper segment", where the reinforcing thread (20) is interwoven with the upper ply (3), then a second segment (22) forming a stay (4) called "descending "which connects said upper segment (21), and therefore the upper ply (3), to the lower ply (2), then a third segment (23) called "lower segment", where the reinforcing thread (20) is interlaced with the lower ply (2), then a fourth segment (24) forming a stay (4) called "upward" which connects said lower segment (23), and therefore the lower ply (2), to the upper ply (3) .

4. Method according to claim 3 characterized in that the direction of introduction (D10) is transverse to the warp direction (DX), and more preferably perpendicular to the warp direction (DX) and therefore parallel to the weft direction (DY), in that the tip penetration (13) of the cutting tool (10) is engaged in the so-called "transverse corridor" space (25) which is comprised between on the one hand a row of descending stays (4, 22), distributed along of the weft direction (DY) and which correspond to the plurality of reinforcing threads (20), and on the other hand the row of ascending stays (4, 24) immediately following, and in that the lower flange (11) is devoid of a cutting blade and arranged so as to slide over the row of lower segments (23) which are integrated into the lower ply (2) plumb with the transverse passage (25), without cutting said lower segments (23) , while the upper flange (12) is provided with a cutting blade (15) which cuts the upper ply (2), in the space comprised between two successive rows of upper segments (21), and therefore without cutting the reinforcing threads (20).

5. Method according to claim 4 characterized in that the width (W12) of the upper sole (12), considered perpendicular to the direction of introduction (D10), is greater than the width (W11) of the lower sole ( 11).

6. Method according to claim 3 characterized in that the insertion direction (D10) is parallel to the warp direction (DX), in that the penetration tip (13) of the cutting tool (10) is engaged in the so-called "longitudinal corridor" space (27) which is comprised between two immediately adjacent parallel reinforcing threads (20), and in that the lower flange (11) and the upper flange (12) are each provided with a cutting blade (15) for simultaneously cutting the lower ply (2) and the upper ply (3) along the warp direction (DX), between said two reinforcing threads (20).

7. Method according to claim 6 characterized in that two cutting tools (10) are simultaneously engaged in two separate parallel longitudinal passages (27) so that the simultaneous cutting operation of the lower (2) and upper ( 3) in each of the two longitudinal corridors (27) makes it possible to subdivide the three-dimensional fabric (1) into a central band (28), between the two longitudinal corridors (27), and two side bands (29, 30).

8. Method according to claim 6 or 7, characterized in that the lower sole (11) and the upper sole (12) each have the shape of a ski provided with a curved spatula (31), and are abutted mirrored by their spatulas. (31) respectively to form the penetration tip (13). - 22 -

9. Method according to one of the preceding claims, characterized in that the cutting movement is generated by moving the three-dimensional fabric (1), in the direction of introduction (D10), relative to the cutting tool (10) which is held fixed.