Method of cutting a selvage of a reinforced sheet

Abstract

The invention relates to a method for cutting a selvedge of a reinforced ply, the reinforced ply comprising reinforcing threads arranged parallel to each other along its length, the cutting method comprising the following consecutive steps: a) capturing at a time t1 and in a portion P1 of predetermined length Lp of the reinforced ply using an imaging device a plurality of successive transverse profiles (PT1, PT2, PT3, etc.) of the reinforced ply moving continuously, b) calculating an average profile of the reinforced ply over said portion P1 of predetermined length Lp from the plurality of transverse profiles (PT1, PT2, PT3, etc.) captured at time t1, c) applying a derived function to this average profile of the reinforced ply, d) determining, from the changes in slope of this derived average profile,of the average position of the cut edge of a selvedge of the reinforced ply and the average position of the last reinforcing thread present in this selvedge,e) calculation of the distance between the average position of the cut edge of the selvedge of the reinforced ply and the average position of the last reinforcing thread present in this selvedge,f) comparison of this distance with a desired value and calculation, where appropriate, of the necessary movement of the cutting tool so that this distance is equal to the desired value. Abstract figure: none,

Description

Title of the invention: Method for cutting a selvage of a reinforced sheet

[0001] The present invention relates to the cutting of the selvedges of a reinforced sheet outside the last reinforcing thread present in each selvedge. More specifically, the invention relates to the control of the distance present between the cut edge of a selvedge of the reinforced sheet and the position of the last reinforcing thread present in this selvedge.

[0002] In the context of tire manufacturing, different layers of rubber material which can contain different types of reinforcing threads are used to make the tire blanks before their curing stage.

[0003] A reinforced ply is generally manufactured by calendering, and it contains a plurality of reinforcing threads arranged parallel to each other along its length and enclosed in a rubbery material. A rubbery material is a material made from natural and / or synthetic rubber and may contain other components such as silica, carbon black, oils, resins and crosslinking agents. Following the calendering step, the edges of the reinforced ply are irregular. In order to be used in the manufacture of a tire blank, the edges must therefore be cut so that the distance between the cut edge of a edge and the last reinforcing thread present in this edge is constant.

[0004] The plies reinforced with longitudinal reinforcing threads can be used directly in the manufacture of a tire blank. But, more generally, these plies reinforced with longitudinal reinforcing threads are intermediate products which must still be transformed before being used in the manufacture of a tire blank.

[0005] Indeed, when making a tire blank, reinforced plies are also used, the reinforcing threads of which can have an angle with the longitudinal direction of the reinforced ply of up to 90°.

[0006] To manufacture these reinforced sheets with reinforcing threads at an angle (with respect to the longitudinal direction of the reinforced sheet), a reinforced sheet with longitudinal reinforcing threads is cut into sections and these sections are butted together along their longitudinal edges so that the reinforcing threads of the different butted sections are parallel to each other.

[0007] Also, to maintain a constant pitch between the angled reinforcing wires along the entire length of the reinforced sheet thus obtained, it is essential that the long edges longitudinal edges of the butted sections, and therefore the edges of the selvedges of the layers reinforced with longitudinal reinforcing threads, are regular, with a constant distance between the cut edge of this selvedge and the last reinforcing thread present in this selvedge.

[0008] Document EP2990168 proposes a method for determining, after cutting the irregular selvedges of a reinforced sheet with longitudinal reinforcing threads, the distance between the last reinforcing thread and the cut edge for each of the two selvedges of the reinforced sheet.

[0009] For this purpose, the method described in document EP2990168 provides: - to generate waveform data by capturing an image of the cross-sectional profile of the reinforced web using an imaging device, and - to detect the positions of peaks of maximum height and troughs of minimum height in the waveform data.

[0010] Then, for each edge of the reinforced sheet, the method described in document EP2990168 provides: - to detect, on the basis of the waveform data, the position of a peak of maximum height closest to the cut edge of the reinforced sheet, - to detect the position of a terminal hollow located beyond the last peak of maximum height and corresponding to the position of the cut edge of the reinforced sheet, - to detect the distance Xm in the transverse direction between the peak of maximum height closest to the cut edge of the reinforced sheet and the terminal hollow located beyond the last peak of maximum height, - to measure the width of the selvedge beyond the last reinforcement based on the detected distance Xm, - to calculate a reference position Y which is a reference point at a predetermined distance Ym,Yn in the transverse direction relative to the position of the peak of maximum height closest to the cut edge of the reinforced ply, and - to move a device for cutting a selvedge of the reinforced sheet so as to reduce the width of said selvedge beyond the last reinforcement when this width exceeds the predetermined distance Ym,Yn from the reference position Y, or to move a device for cutting a selvedge of the reinforced sheet so as to increase the width of said selvedge beyond the last reinforcement when this width does not reach the predetermined distance Ym,Yn from the reference position Y.

[0011] According to a first drawback, the method for determining the width of a selvedge beyond the last reinforcement described in document EP2990168 is not suitable for industrial use.

[0012] Indeed, the reinforced sheets manufactured by calendering are not perfect and they present, in random places, asperities (hollow shapes) and protrusions. berances (relief shapes) which can be interpreted, depending on their position, as peaks of maximum height and terminal troughs in the method described in document EP2990168. These random asperities and protuberances can therefore lead to inconsistent results and poor corrections of the position of the cutting tool.

[0013] Therefore, by working profile by profile and directly from the waveform data corresponding to each cross-sectional profile of the reinforced ply, the determination method described in document EP2990168 can only be operational with a reinforced ply of almost perfect shape and having relatively similar consecutive cross-sectional profiles.

[0014] According to another drawback, to allow the detection of the different peaks of maximum height and troughs of minimum height directly and quickly from the data in wave form, the imaging device used with the method described in document EP2990168 must be perfectly calibrated and very precise.

[0015] The present invention aims to propose a method for cutting the edges of a reinforced sheet with a determination of the distance between the cut edge of a sheet and the last reinforcement present in this sheet which is applicable to reinforced sheets which are not perfect and which may have asperities (hollow shapes) and protuberances (raised shapes).

[0016] To this end, the invention relates to a method of cutting a selvedge of a reinforced sheet comprising reinforcing threads arranged parallel to each other along its length.

[0017] According to the invention, the cutting method comprises the following consecutive steps: a) capturing at a time tl using an imaging device a plurality of successive transverse profiles of the reinforced sheet which passes continuously under the imaging device after cutting its edges, the plurality of successive transverse profiles being captured in a portion PI of predetermined length Lp of the reinforced sheet, and each transverse profile taking the form of data in wave form, b) calculating an average profile of the reinforced ply over said portion PI of predetermined length Lp from the plurality of transverse profiles captured at time tl, c) applying a derived function to this average profile of the reinforced ply at time tl and over said portion PI of predetermined length Lp, d) determination, from the changes in slope of this derived average profile, of the average position of the cut edge of a selvedge of the reinforced ply and of the average position of the last reinforcing thread present in this selvedge at time tl and on said portion PI of predetermined length Lp, e) calculation of the distance between the average position of the cut edge of the selvedge of the reinforced sheet and the average position of the last reinforcing thread present in this selvedge at time tl and on said portion PI of predetermined length Lp, f) comparison of this distance with a desired value and calculation, where appropriate, of the necessary movement of the cutting tool so that this distance is equal to the desired value.

[0018] By calculating an average profile of the reinforced ply over a portion of predetermined length from a plurality of transverse profiles, the cutting method according to the invention is not disturbed by any roughness or protrusions that may appear randomly on certain transverse profiles. In addition, the use of the derivative of the average profile makes it possible to facilitate and make more reliable the detection of inflection points (changes in slope) and therefore the detection of the position of the cut edge of a selvedge of the reinforced ply and the detection of the position of the last reinforcing thread present in this selvedge.

[0019] Advantageously but not necessarily, the invention can also provide that: - steps a) to f) are repeated regularly at different successive times (t1, t2, t3,...) and on different successive portions (P1, P2, P3,...) of predetermined length Lp of the reinforced sheet, - the different successive instants (tl, t2, t3,...) are sufficiently spaced in time so that two successive portions (P1, P2, P3,...) of predetermined length Lp have no transverse profile (PT1, PT2, PT3,...) in common, or that the different successive instants (t1, t2, t3,...) are sufficiently close in time so that two successive portions (P1, P2, P3,...) of predetermined length Lp have a plurality of transverse profiles (PT1, PT2, PT3,...) in common, - two successive portions (P1, P2, P3,...) have between 3% and 10% of transverse profiles (PT1, PT2, PT3,...) in common, - during step a) and with a view to carrying out step b), the imaging device captures between 1000 and 1800, preferably between 1300 and 1500, transverse profiles (PT1, PT2, PT3,...) in a portion (P1, P2, P3,...) of predetermined length Lp, - the predetermined length Lp of a portion (P1, P2, P3,...) of the reinforced sheet in which the plurality of successive transverse profiles (PT1, PT2, PT3,...) is captured is between 15 and 25 cm, preferably between 18 and 22 cm, - a low-pass filter is applied to the derived average profile obtained in step c) before its use in step d), - the width of a selvedge between its cut edge and the last reinforcing thread present in this selvedge is between 150 and 250 pm, - the reinforced sheet moves continuously under the imaging device at a speed greater than 50 m / min, and for example greater than 100 m / min, - the imaging device used in step a) is a profilometer with a resolution at least equal to 10 pm and a field length less than or equal to 40 mm.

[0020] Other characteristics and advantages of the invention will appear in the description which follows. This description, given by way of example and not as a limitation, refers to the attached drawings in which: - [Fig.l] schematically represents a top view of an installation for cutting the edges of a reinforced sheet in which the cutting method according to the invention can be implemented, - [Fig.2] illustrates a first step of the cutting process according to the invention which consists of capturing different transverse profiles of a reinforced sheet, - [Fig.3] illustrates a second step of the cutting method according to the invention which consists of calculating an average profile of a reinforced ply over a determined length from a plurality of transverse profiles of a reinforced ply, - [Fig.4] illustrates a third step of the cutting method according to the invention which consists of applying a derived function to an average profile of a reinforced sheet over a predetermined length, - [Fig.5] illustrates a fourth step of the cutting method according to the invention which consists of determining the position of the cut edge of a selvedge of the reinforced sheet and the position of the last reinforcing thread present in this selvedge, - [Fig.6] represents a fifth step of the cutting method according to the invention which consists of calculating the distance between the position of the cut edge of the selvedge of the reinforced sheet and the position of the last reinforcing thread present in this selvedge.

[0021] The invention relates to the cutting of the edges of a reinforced sheet, and more particularly to the precise cutting of the edges of a reinforced sheet with longitudinal reinforcements.

[0022] For example, a reinforced ply 12 comprises between 100 and 2500 reinforcing threads 14 arranged parallel to each other along its length L12. For example, the reinforcing threads 14 are coated in a rubbery material 16. A rubbery material is a material made from natural and / or synthetic rubber and may contain other components such as silica, carbon black and oils. The reinforcing threads may be metallic or textile. The reinforcing threads of a reinforced ply have, for example, substantially the same diameter. For example, the reinforcing threads 14 have a diameter of between 0.3 and 7 mm. For example, a reinforced ply 12 has a thickness E12 of between 0.4 and 10 mm. For example, a reinforced ply 12 has a width W12 of between 1 and 145 cm.

[0023] The invention proposes a method for cutting a selvedge of a reinforced sheet which can be implemented in a cutting installation 10 such as that illustrated schematically in [Fig.l].

[0024] The cutting installation 10 is located for example at the exit of the calender 20 which manufactures the reinforced web 12 whose edges are to be cut. In such a cutting installation 10, the reinforced web advances continuously as long as the calender 20 is not stopped. For example, the reinforced web 12 is moved in translation in a direction of advance DD corresponding to its direction of exit from the calender. For example, the reinforced web 12 is moved on a belt conveyor (not shown in [Fig.l]). Preferably, the reinforced web 12 is moved in translation in a horizontal plane.

[0025] The cutting installation 10 comprises two right 22D and left 22G cutting devices for precisely cutting the right 18D and left 18G selvedges of the reinforced ply. These two right 22D and left 22G cutting devices are located on either side of the width W12 of the reinforced ply. For example, these two right 22D and left 22G cutting devices are located above the reinforced ply. Each cutting device 22D, 22G comprises a cutting tool, such as a blade or a knife, the position of which is adjustable in a transverse direction DT perpendicular to the direction of travel DD of the reinforced ply. Preferably, the position of the cutting tool of each cutting device is adjustable automatically via an actuator (not shown).

[0026] In order to check the quality of the cutting of the right 18D and left 18G selvedges of the reinforced ply, the cutting installation 10 comprises an imaging device 24 located downstream of the cutting devices 22D, 22G in the running direction DD. This imaging device 24 makes it possible to capture transverse profiles PT1, PT2,... of the reinforced ply after cutting its selvedges. Ideally, the imaging device 24 makes it possible to capture transverse profiles PT1, PT2,... of the reinforced ply over its entire width W12, and therefore integrating the two selvedges of the reinforced ply with their respective cut edge. Preferably, the imaging device 24 is located above the reinforced ply.

[0027] The two right 22D and left 22G cutting devices and the imaging device 24 are connected to a control unit 26 of the cutting installation. This control unit 26 makes it possible to manage the position of the cutting tools of the cutting devices 22D, 22G in the transverse direction DT as a function of the information transmitted by the imaging device 24 concerning the position of the cut edge of each selvedge relative to the last reinforcement present in this selvedge.

[0028] The last reinforcement present in a selvedge is the last reinforcement present in the reinforced ply when moving in the transverse direction DT corresponding to the width of the reinforced ply and from the center of the reinforced ply towards the longitudinal edge formed by this selvedge.

[0029] Preferably, the imaging device 24 is a linear laser beam profilometer, for example of the Keyence® brand. For example, this profilometer offers a resolution at least equal to 10 pm and a field length less than or equal to 40 mm. For example, the profilometer is positioned between 50 and 90 mm above the reinforced sheet 12 which passes below it.

[0030] To enable the implementation of the cutting method according to the invention, the reinforcing threads 14 of a reinforced ply 12 must form undulations on the upper surface 18 of the reinforced ply, as shown in [Fig.2]. Indeed, the cutting method according to the invention uses the variations in thickness of the reinforced ply measured by the imaging device 24 to deduce therefrom the position of the last reinforcement present in a selvedge of the reinforced ply and the position of the cut edge of this selvedge.

[0031] In the cutting method according to the invention and in the cutting installation illustrated in [Fig.l], the reinforced sheet 12 passes continuously under the imaging device 24 at a speed greater than 50 m / min, and for example greater than 100 m / min.

[0032] According to the invention, in a first step illustrated by [Fig.2], the cutting method provides for capturing at a time t1 using the imaging device 24 a plurality of successive transverse profiles PT1, PT2, PT3, PT4,... of the reinforced ply 12 which passes continuously under the imaging device after cutting its edges. In more detail, during this first step, the successive transverse profiles PT1, PT2, PT3, PT4,... are captured in a portion PI of predetermined length Lp of the reinforced ply. In this first step and with a view to the next step, the imaging device 24 captures between 1000 and 1800, preferably between 1300 and 1500, transverse profiles PT1, PT2, PT3,... in a portion PI of predetermined length Lp. For example, the predetermined length Lp of a portion PI of the reinforced sheet in which the plurality of successive transverse profiles PT1, PT2, PT3,... is captured.is between 15 and 25 cm, preferably between 18 and 22 cm.

[0033] Each transverse profile PT1, PT2, PT3, PT4,... captured by the imaging device 24 takes the form of data in wave form. More precisely and as can be seen in [Fig. 3], each transverse profile PT1, PT2, PT3, PT4,... takes for example the form of a curve C. Each transverse profile PT1, PT2, PT3, PT4,... represents the variations in thickness of the reinforced ply 12 in its width. In [Fig. 3], the thickness E12 of the reinforced ply is indicated on the ordinate and the position in the width of the reinforced ply is indicated on the abscissa. Preferably, each transverse profile PT1, PT2, PT3, PT4,... represents the variations in thickness E12 of the reinforced ply in its entire width W12, and therefore for its two right 18D and left 18G edges.

[0034] In a second step illustrated by [Fig.3], the cutting method provides for calculating an average profile PM of the reinforced sheet 12 on said portion PI of predetermined length Lp from the plurality of transverse profiles PT1, PT2, PT3, PT4,... captured at time tl by the imaging device 24. For example, this average profile PM is obtained by calculating from a multitude of positions taken regularly in the width of the reinforced ply the average thickness of the different transverse profiles PT1, PT2, PT3, PT4,... for each of these different positions. Thanks to the calculation of this average profile PM, the irregularities of the reinforced ply do not destabilize the measurements carried out subsequently by the cutting method according to the invention. The average profile PM obtained during this second step makes it possible to give a stable image representative of the real profile of the reinforced ply without its irregularities.

[0035] In a third step illustrated in [Fig.4], and in order to facilitate the detection of changes in slope of the average profile PM due to the presence of the reinforcements 14 in the ply 12 and to the cut edges of the selvedges of the ply, the cutting method provides for applying a derivative function to the average profile PM of the reinforced ply at time t1 and on said portion PI of predetermined length Lp. More precisely, the cutting method provides for calculating the derivative of the thickness of the reinforced ply with respect to the position in the width of the reinforced ply. The derived average profile PMD thus obtained represents the amplitude of the variations in thickness of the reinforced ply as a function of the position in the width of the reinforced ply.

[0036] In a fourth step illustrated in [Fig.5], the cutting method provides for determining, from the changes in slope of the derived mean profile PMD, the mean position Ya of the cut edge of a selvedge of the reinforced ply and the mean position Yb of the last reinforcing yarn present in this selvedge at time tl and over said portion PI of predetermined length Lp. More precisely, the derived mean profile PMD makes it possible to identify the mean position Yb of the central axis, or neutral fiber, of the last reinforcement in each selvedge of the reinforced ply. The mean position Ya of the cut edge of each selvedge corresponds to the inflection point which is located furthest to the outside in this selvedge. The mean position Yb of the central axis of the last reinforcing yarn in each selvedge corresponds to the inflection point which is located before the two outermost inflection points in this selvedge.For example, the inflection points corresponding to the average position Ya of the cut edge of a selvedge and the average position Yb of the central axis of the last reinforcement yarn in a selvedge are identified from predefined amplitude thresholds which make it possible to ignore the lower amplitude inflection points, such as those which are for example due to noise in the processed signal or to a localized deformation of the reinforced sheet.

[0037] In a fifth step illustrated in [Fig.6], the cutting method provides for calculating the distance D between the average position Ya of the cut edge of the selvedge of the reinforced ply and the average position Yb of the last reinforcing thread present in this selvedge at time tl and on said portion PI of predetermined length Lp. Knowing the diameter D14 of a reinforcement 14, this calculation makes it possible to determine the length L of the selvedge using the following formula: L = D - (D14 / 2).

[0038] Then, in a sixth step, the cutting method provides for comparing this distance D with a desired value and calculating, if necessary, the necessary movement of the cutting tool so that this distance D is equal to the desired value, and so that the selvedge has the desired width L. For example, the width L of a selvedge between its cut edge and the last reinforcing thread present in this selvedge is between 150 and 250 μm.

[0039] Advantageously, the cutting method may provide that a low-pass filter is applied to the derived mean profile PMD obtained during the third step and before its use in the fourth step. This low-pass filter makes it possible to remove the last errors (noise) due to the irregularities of the reinforced sheet.

[0040] As the reinforced sheet 12 passes continuously under the imaging device 24, the cutting method provides that the different steps are repeated regularly at different successive times t1, t2, t3, ... and on different successive portions P1, P2, P3, ... of predetermined length Lp of the reinforced sheet in order to continuously measure the distance between the average position of the cut edge of a selvedge of the reinforced sheet and the average position of the last reinforcing thread present in this selvedge. In a first variant of implementation of the cutting method according to the invention, the different successive times t1, t2, t3, ... are sufficiently spaced in time so that two successive portions P1, P2, P3, ... of predetermined length Lp have no transverse profile PT1, PT2, PT3, ... in common. In a second variant of implementation of the cutting method according to the invention, the different successive times 11, t2, t3, ...are sufficiently close together in time so that two successive portions P1, P2, P3,... of predetermined length Lp have a plurality of transverse profiles PT1, PT2, PT3,... in common. For example, in this second variant, two successive portions P1, P2, P3,... have between 3% and 10% of transverse profiles PT1, PT2, PT3,... in common. For the application targeted by the cutting method according to the invention, it is not useful for two successive portions P1, P2, P3,... to have more than 10% of transverse profiles PT1, PT2, PT3,... in common. In addition, this makes it possible to limit the use of the resources of the imaging device 24 and of the control unit 26 of the cutting installation.

[0041] As indicated previously, the imaging device 24 makes it possible to capture transverse profiles PT1, PT2,... of the reinforced ply over its entire width W12, and therefore integrating the two edges of the reinforced ply with their respective cut edge. Consequently, the cutting method according to the invention also provides for measuring the distance between the average position of the cut edge of each of the two edges of the reinforced sheet and the average position of the last reinforcing thread present in each of these two selvedges. In more detail, and after the implementation of the first three steps, the cutting method according to the invention may comprise the following consecutive steps: - determination, from the changes in slope of this derived mean profile (DMP), of the average position of the cut edge of each of the two selvedges of the reinforced ply and of the average position of the last reinforcing thread present in each of these two selvedges at time tl and on said portion PI of predetermined length Lp, - calculation of the distance between the average position of the cut edge of each of the two selvedges of the reinforced ply and the average position of the last reinforcing thread present in each of these two selvedges at time tl and on said portion PI of predetermined length Lp, - comparison of this distance with a desired value and calculation, if necessary, of the necessary movement of the cutting tool corresponding to each of these two edges so that this distance is equal to the desired value.

[0042] Preferably, the cutting method according to the invention also provides for continuously measuring the distance between the average position of the cut edge of each of the two selvedges of the reinforced ply and the average position of the last reinforcing thread present in each of these two selvedges. To this end, it provides for regularly repeating at different successive times (t1, t2, t3, etc.) and on different successive portions (P1, P2, P3, etc.) of predetermined length Lp of the reinforced ply the steps described above.

Claims

Claims

1. Method for cutting a selvedge of a reinforced ply, the reinforced ply comprising reinforcing threads arranged parallel to each other along its length, the cutting method comprising the following consecutive steps: a) capturing at a time tl using an imaging device a plurality of successive transverse profiles (PT1, PT2, PT3,...) of the reinforced ply which passes continuously under the imaging device after cutting its selvedge, the plurality of successive transverse profiles (PT1, PT2, PT3,...) being captured in a portion PI of predetermined length Lp of the reinforced ply, and each transverse profile (PT1, PT2, PT3,...) taking the form of data in wave form, b) calculating an average profile (PM) of the reinforced ply over said portion PI of predetermined length Lp from the plurality of transverse profiles (PT1, PT2, PT3,...) captured at time tl, c) application of a derivative function to this mean profile (PM) of the reinforced ply at time tl and on said portion PI of predetermined length Lp, d) determination, from the changes in slope of this derived mean profile (PMD), of the mean position of the cut edge of a selvedge of the reinforced ply and the mean position of the last reinforcing wire present in this selvedge at time tl and on said portion PI of predetermined length Lp, e) calculation of the distance between the mean position of the cut edge of the selvedge of the reinforced ply and the mean position of the last reinforcing wire present in this selvedge at time tl and on said portion PI of predetermined length Lp, f) comparison of this distance with a desired value and calculation, where appropriate, of the necessary displacement of the cutting tool so that this distance is equal to the desired value.

2. Cutting method according to claim 1, in which steps a) to f) are repeated regularly at different successive times (t1, t2, t3,...) and on different successive portions (P1, P2, P3,...) of predetermined length Lp of the reinforced sheet.

3. Cutting method according to claim 2, in which the different successive instants (t1, t2, t3,...) are sufficiently spaced in time so that two successive portions (P1, P2, P3,...) of predetermined length completed Lp have no transverse profile (PT1, PT2, PT3,...) in common, or in which the different successive instants (tl, t2, t3,...) are sufficiently close in time so that two successive portions (P1, P2, P3,...) of predetermined length Lp have a plurality of transverse profiles (PT1, PT2, PT3,...) in common.

4. Cutting method according to claim 3, in which two successive portions (P1, P2, P3,...) have between 3% and 10% of transverse profiles (PT1, PT2, PT3,...) in common.

5. Cutting method according to one of the preceding claims, in which, during step a) and with a view to carrying out step b), the imaging device captures between 1000 and 1800, preferably between 1300 and 1500, transverse profiles (PT1, PT2, PT3,...) in a portion (P1, P2, P3,...) of predetermined length Lp.

6. Cutting method according to one of the preceding claims, in which the predetermined length Lp of a portion (P1, P2, P3,...) of the reinforced sheet in which the plurality of successive transverse profiles (PT1, PT2, PT3,...) is captured is between 15 and 25 cm, preferably between 18 and 22 cm.

7. Cutting method according to one of the preceding claims, in which a low-pass filter is applied to the derived mean profile (DMP) obtained in step c) before its use in step d).

8. Cutting method according to one of the preceding claims, in which the width of a selvedge between its cut edge and the last reinforcing thread present in this selvedge is between 150 and 250 pm.

9. Cutting method according to one of the preceding claims, in which the reinforced sheet moves continuously under the imaging device at a speed greater than 50 m / min, and for example greater than 100 m / m 1 n

10. 111111. Cutting method according to one of the preceding claims, in which the imaging device used in step a) is a profilometer with a resolution at least equal to 10 pm and a field length less than or equal to 40 mm.

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