Method for cutting the edge of a reinforced tablecloth
The method addresses industrial inconsistencies in cutting reinforced sheets by averaging cross-sectional profiles and adjusting cutting tools to achieve consistent thread spacing, ensuring precise and reliable cutting.
Patent Information
- Application Number
- FR2023013770
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-12-07
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2043-12-07
Smart Images
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Abstract
Description
Title of the invention: Method for cutting the edge of a reinforced tablecloth
[0001] The present invention relates to cutting the edges of a reinforced web outside the last reinforcing thread present in each edge. More specifically, the invention concerns controlling the distance between the cut edge of an edge of the reinforced web and the position of the last reinforcing thread present in that edge.
[0002] In the context of tire manufacturing, different layers of rubbery material that 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 contains a plurality of reinforcing yarns 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 selvedges of the reinforced ply are irregular. Therefore, to be used in the manufacture of a tire blank, the selvedges must be cut so that the distance between the cut edge of a selvage and the last reinforcing yarn present in that selvage is constant.
[0004] Reinforced plies with longitudinal reinforcing threads can be used directly in the manufacture of a tire blank. However, more generally, these plies reinforced with longitudinal reinforcing threads are intermediate products that must be further processed before being used in the manufacture of a tire blank.
[0005] Indeed, when making a prototype tire, 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 wires at an angle (with respect to the longitudinal direction of the reinforced sheet), a reinforced sheet with longitudinal reinforcing wires is cut into sections and these sections are butted together along their longitudinal edges so that the reinforcing wires of the different butted sections are parallel to each other.
[0007] Also, in order to maintain a constant spacing between the angled reinforcing wires along the entire length of the reinforced sheet thus obtained, it is essential that the longitudinal edges tubulars of butted sections, and therefore the edges of the selvedges of the sheets reinforced with longitudinal reinforcing wires, are regular, with a constant distance between the cut edge of this selvage and the last reinforcing wire present in this selvage.
[0008] Document EP2990168 proposes a method for determining, after cutting the irregular edges of a reinforced sheet with longitudinal reinforcing wires, the distance between the last reinforcing wire and the cut edge for each of the two edges of the reinforced sheet.
[0009] To this end, the process described in document EP2990168 provides for: - to generate data in wave form by capturing an image of the cross-sectional profile of the reinforced layer using an imaging device, and - to detect the positions of peaks of maximum height and troughs of minimum height in waveform data.
[0010] Next, for each edge of the reinforced layer, the process described in document EP2990168 provides: - to detect, based on wave data, the position of the highest peak 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 layer, - to detect the distance Xm in the transverse direction between the highest peak closest to the cut edge of the reinforced sheet and the terminal hollow located beyond the last highest peak, - to measure the width of the selvage 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 maximum height ridge closest to the cut edge of the reinforced sheet, and - to move a cutting device of an edge of the reinforced sheet so as to reduce the width of said edge beyond the last reinforcement when this width exceeds the predetermined distance Ym,Yn from the reference position Y, or to move a cutting device of an edge of the reinforced sheet so as to increase the width of said edge 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 selvage beyond the last reinforcement described in document EP2990168 is not suitable for industrial use.
[0012] Indeed, reinforced sheets manufactured by calendering are not perfect and exhibit, in random places, asperities (hollow shapes) and protrusions berances (raised shapes) which can be interpreted, depending on their position, as peaks of maximum height and terminal hollows in the process described in document EP2990168. These random asperities and protrusions can therefore lead to inconsistent results and poor corrections of the cutting tool position.
[0013] Therefore, by working profile by profile and directly from the waveform data corresponding to each cross-sectional profile of the reinforced sheet, the determination method described in document EP2990168 can only be operational with a reinforced sheet of almost perfect shape and exhibiting relatively similar consecutive cross-sectional profiles.
[0014] According to another drawback, in order 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 provide a method for cutting the edges of a reinforced sheet with a determination of the distance between the cut edge of an edge and the last reinforcement present in this edge 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 for cutting an edge of a reinforced sheet comprising reinforcing threads arranged parallel to each other along its length.
[0017] According to the invention, the cutting process comprises the following consecutive steps: a) capture at a time tl using an imaging device of a plurality of successive cross-sectional profiles of the reinforced sheet which passes continuously under the imaging device after cutting its edges, the plurality of successive cross-sectional profiles being captured in a portion PI of predetermined length Lp of the reinforced sheet, and each cross-sectional profile taking the form of wave-form data, b) calculation of an average profile of the reinforced sheet over said portion PI of predetermined length Lp from the plurality of transverse profiles captured at time tl, c) application of a derivative function to this average profile of the reinforced sheet 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 strip of the reinforced layer and of the average position of the last reinforcing wire present in this strip 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 selvage of the reinforced layer and the average position of the last reinforcing wire present in this selvage at time tl and on said portion PI of predetermined length Lp, f) comparison of this distance with a desired value and calculation, if necessary, of the necessary displacement of the cutting tool so that this distance is equal to the desired value.
[0018] By calculating an average profile of the reinforced sheet over a predetermined length from a plurality of cross-sectional profiles, the cutting process according to the invention is not affected by any asperities or protrusions that may randomly appear on certain cross-sectional profiles. Furthermore, the use of the derivative of the average profile makes it easier and more reliable to detect inflection points (changes in slope) and therefore to detect the position of the cut edge of a strip of the reinforced sheet and the position of the last reinforcing wire present in that strip.
[0019] Advantageously but not necessarily, the invention may 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 mat, - the different successive instants (t1, t2, t3,...) are sufficiently spaced in time so that two successive portions (P1, P2, P3,...) of predetermined length Lp have no cross-sectional 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 cross-sectional profiles (PT1, PT2, PT3,...) in common, - two successive sections (P1, P2, P3, ...) have between 3% and 10% of their cross-sectional profiles (PT1, PT2, PT3, ...) in common, - during step a) and in view of 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 layer in which the plurality of successive cross-sectional profiles (PT1,PT2,PT3,...) are captured is between 15 and 25 cm, preferably between 18 and 22 cm, - a low-pass filter is applied to the derived mean profile obtained in step c) before its use in step d), - the width of a selvage between its cut edge and the last reinforcing thread present in this selvage is between 150 and 250 pm, - the reinforced sheet passes 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 features and advantages of the invention will become apparent in the following description. This description, given by way of example and not limitation, refers to the attached drawings in which: - [Fig. 1] schematically represents a top view of an installation for cutting the edges of a reinforced sheet in which the cutting process 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 process according to the invention, which consists of calculating an average profile of a reinforced sheet over a determined length from a plurality of transverse profiles of a reinforced sheet, - [Fig.4] illustrates a third step of the cutting process 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 process according to the invention, which consists of determining the position of the cut edge of a selvage of the reinforced fabric and the position of the last reinforcing thread present in this selvage, - [Fig.6] represents a fifth step of the cutting process according to the invention which consists of calculating the distance between the position of the cut edge of the selvage of the reinforced sheet and the position of the last reinforcing wire present in this selvage.
[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 web 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 web, for example, have substantially the same diameter. For example, the reinforcing threads 14 have a diameter of between 0.3 and 7 mm. For example, a reinforced web 12 has a thickness E12 of between 0.4 and 10 mm. For example, a reinforced web 12 has a width W12 of between 1 and 145 cm.
[0023] The invention proposes a method for cutting an edge of a reinforced sheet which can be implemented in a cutting installation 10 such as that schematically illustrated in [Fig.1].
[0024] The cutting installation 10 is located, for example, at the exit of the calender 20 which The reinforced web 12 is manufactured, and its edges are to be cut. In such a cutting installation 10, the reinforced web flows continuously as long as the calender 20 is not stopped. For example, the reinforced web 12 is moved in translation in a direction of travel DD corresponding to its exit direction from the calender. For example, the reinforced web 12 is moved on a belt conveyor (not shown in [Fig. 1]). Preferably, the reinforced web 12 is moved in translation in a horizontal plane.
[0025] The cutting installation 10 includes two cutting devices, right 22D and left 22G, for precisely cutting the right 18D and left 18G edges of the reinforced web. These two cutting devices, right 22D and left 22G, are located on either side of the width W12 of the reinforced web. For example, these two cutting devices, right 22D and left 22G, are located above the reinforced web. Each cutting device 22D, 22G includes a cutting tool, such as a blade or knife, the position of which is adjustable in a transverse direction DT perpendicular to the direction of travel DD of the reinforced web. Preferably, the position of the cutting tool of each cutting device is automatically adjustable via an actuator (not shown).
[0026] To verify the quality of the cutting of the right edge 18D and left edge 18G of the reinforced sheet, the cutting installation 10 includes an imaging device 24 located downstream of the cutting devices 22D, 22G in the direction of travel DD. This imaging device 24 captures cross-sectional profiles PT1, PT2,... of the reinforced sheet after its edges have been cut. Ideally, the imaging device 24 captures cross-sectional profiles PT1, PT2,... of the reinforced sheet across its entire width W12, thus including both edges of the reinforced sheet with their respective cut edges. Preferably, the imaging device 24 is located above the reinforced sheet.
[0027] The two cutting devices, right 22D and left 22G, and the imaging device 24 are connected to a control unit 26 of the cutting installation. This control unit 26 manages the position of the cutting tools of the cutting devices 22D, 22G in the transverse direction DT according to the information transmitted by the imaging device 24 concerning the position of the cut edge of each selvage relative to the last reinforcement present in that selvage.
[0028] The last reinforcement present in a selvage is the last reinforcement present in the reinforced layer when moving in the transverse direction DT corresponding to the width of the reinforced layer and from the center of the reinforced layer towards the longitudinal edge formed by this selvage.
[0029] Preferably, the imaging device 24 is a linear laser beam profilometer, for example from 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 beneath it.
[0030] To enable the implementation of the cutting process according to the invention, the reinforcing wires 14 of a reinforced web 12 must form undulations on the upper surface 18 of the reinforced web, as shown in [Fig. 2]. Indeed, the cutting process according to the invention uses the variations in thickness of the reinforced web measured by the imaging device 24 to deduce the position of the last reinforcement present in an edge of the reinforced web and the position of the cut edge of this edge.
[0031] In the cutting process according to the invention and in the cutting installation illustrated in [Fig.1], 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 process involves capturing, at time t1, using the imaging device 24, a plurality of successive cross-sectional profiles PT1, PT2, PT3, PT4,... of the reinforced sheet 12, which passes continuously under the imaging device after its edges have been cut. More specifically, during this first step, the successive cross-sectional profiles PT1, PT2, PT3, PT4,... are captured in a portion PI of predetermined length Lp of the reinforced sheet. In this first step and in preparation for the next step, the imaging device 24 captures, between 1000 and 1800, preferably between 1300 and 1500, cross-sectional 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 aquifer in which the plurality of successive cross-sectional profiles PT1, PT2, PT3,... are capturedis between 15 and 25 cm, preferably between 18 and 22 cm.
[0033] Each cross-sectional profile PT1, PT2, PT3, PT4,... captured by the imaging device 24 takes the form of wave-like data. More precisely, and as can be seen in [Fig. 3], each cross-sectional profile PT1, PT2, PT3, PT4,... takes, for example, the form of a curve C. Each cross-sectional profile PT1, PT2, PT3, PT4,... represents the variations in thickness of the reinforced sheet 12 across its width. In [Fig. 3], the thickness E12 of the reinforced sheet is shown on the ordinate axis, and its position across the width of the reinforced sheet is shown on the abscissa axis. Preferably, each cross-sectional profile PT1, PT2, PT3, PT4,... represents the variations in thickness E12 of the reinforced sheet across its entire width W12, and therefore for both its right edge 18D and left edge 18G.
[0034] In a second step illustrated by [Fig. 3], the cutting process involves calculating an average profile PM of the reinforced layer 12 on said portion PI of The predetermined length Lp is derived 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 across the width of the reinforced sheet, 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, irregularities in the reinforced sheet do not destabilize the measurements subsequently performed by the cutting process according to the invention. The average profile PM obtained during this second step provides a stable and representative image of the actual profile of the reinforced sheet without its irregularities.
[0035] In a third step illustrated in [Fig. 4], and in order to facilitate the detection of changes in the slope of the mean profile PM due to the presence of the reinforcements 14 in the layer 12 and the cut edges of the layer's margins, the cutting process involves applying a derivative function to the mean profile PM of the reinforced layer at time t1 and over said portion PI of predetermined length Lp. More precisely, the cutting process involves calculating the derivative of the thickness of the reinforced layer with respect to its position across the width of the reinforced layer. The derived mean profile PMD thus obtained represents the magnitude of the variations in the thickness of the reinforced layer as a function of its position across its width.
[0036] In a fourth step illustrated in [Fig. 5], the cutting process involves determining, from the changes in slope of the derived mean profile PMD, the average position Ya of the cut edge of a selvage of the reinforced web and the average position Yb of the last reinforcing wire present in this selvage at time t1 and on said portion PI of predetermined length Lp. More precisely, the derived mean profile PMD makes it possible to identify the average position Yb of the central axis, or neutral fiber, of the last reinforcement in each selvage of the reinforced web. The average position Ya of the cut edge of each selvage corresponds to the inflection point located furthest out in that selvage. The average position Yb of the central axis of the last reinforcing wire in each selvage corresponds to the inflection point located before the two outermost inflection points in that selvage.For example, the inflection points corresponding to the average position Ya of the cut edge of a selvage and the average position Yb of the central axis of the last reinforcing wire in a selvage are identified from predefined amplitude thresholds which allow to ignore inflection points of lower amplitude, such as those which are due for example to noise of the processed signal or to a localized deformation of the reinforced pad.
[0037] In a fifth step illustrated in [Fig. 6], the cutting process involves calculating the distance D between the average position Ya of the cut edge of the reinforced web's selvage and the average position Yb of the last reinforcing wire present in this edge at time tl and on said portion PI of predetermined length Lp. Knowing the diameter D14 of a reinforcement 14, this calculation allows us to determine the length L of the edge using the following formula: L = D - (D14 / 2).
[0038] Then, in a sixth step, the cutting process compares this distance D with a desired value and calculates, if necessary, the required displacement of the cutting tool so that this distance D equals the desired value, and the selvage has the required width L. For example, the width L of a selvage between its cut edge and the last reinforcing thread in that selvage is between 150 and 250 µm.
[0039] Advantageously, the cutting process may provide that a low-pass filter is applied to the derived PMD mean profile obtained in the third step and before its use in the fourth step. This low-pass filter makes it possible to eliminate the last errors (noise) due to irregularities in the reinforced sheet.
[0040] As the reinforced sheet 12 passes continuously under the imaging device 24, the cutting process 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 selvage of the reinforced sheet and the average position of the last reinforcing wire present in that selvage. In a first embodiment of the cutting process 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 embodiment of the cutting process according to the invention, the different successive times t1, t2, t3,...are sufficiently close in time so that two successive portions P1, P2, P3,... of predetermined length Lp have a plurality of cross-sectional profiles PT1, PT2, PT3,... in common. For example, in this second variant, two successive portions P1, P2, P3,... have between 3% and 10% of their cross-sectional profiles PT1, PT2, PT3,... in common. For the application targeted by the cutting process according to the invention, it is not necessary for two successive portions P1, P2, P3,... to have more than 10% of their cross-sectional profiles PT1, PT2, PT3,... in common. Moreover, this limits the use of resources in the imaging device 24 and the control unit 26 of the cutting installation.
[0041] As previously stated, the imaging device 24 makes it possible to capture transverse profiles PT1, PT2,... of the reinforced sheet over its entire width W12, and thus incorporating the two edges of the reinforced sheet with their respective cut edges. Consequently, the cutting process 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 layer 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 process according to the invention may comprise the following consecutive steps: - determination, from the changes in slope of this derived mean profile (PMD), of the average position of the cut edge of each of the two edges of the reinforced layer and of the average position of the last reinforcing wire present in each of these two edges 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 edges of the reinforced layer and the average position of the last reinforcing wire present in each of these two edges 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 displacement 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 process 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 web 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,...) and on different successive portions (P1, P2, P3,...) of predetermined length Lp of the reinforced web, the steps described above.
Claims
Demands
1. A method for cutting an edge of a reinforced web, the reinforced web comprising reinforcing wires arranged parallel to each other along its length, the cutting method comprising the following consecutive steps: a) capturing at time tl, using an imaging device, a plurality of successive cross-sectional profiles (PT1, PT2, PT3, ...) of the reinforced web as it passes continuously under the imaging device after its edges have been cut, the plurality of successive cross-sectional profiles (PT1, PT2, PT3, ...) being captured in a portion PI of predetermined length Lp of the reinforced web, and each cross-sectional profile (PT1, PT2, PT3, ...) taking the form of wave-like data, b) calculating an average profile (PM) of the reinforced web over said portion PI of predetermined length Lp from the plurality of cross-sectional profiles (PT1, PT2, PT3, ...) captured at time tl, c) application of a derivative function to this average profile (PM) of the reinforced sheet at time tl and on said portion PI of predetermined length Lp, d) determination, from the changes in slope of this derived average profile (PMD), of the average position of the cut edge of a selvage of the reinforced sheet and of the average position of the last reinforcing wire present in this selvage 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 selvage of the reinforced sheet and the average position of the last reinforcing wire present in this selvage at time tl and on said portion PI of predetermined length Lp, f) comparison of this distance with a desired value and calculation, if necessary, 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, wherein 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. A cutting method according to claim 2, wherein the various successive instants (t1, t2, t3,...) are sufficiently spaced in time so that two successive portions (P1, P2, P3,...) of predetermined length finished Lp have no cross-sectional profile (PT1,PT2,PT3,...) in common, or in which the different successive instants (t1,t2,t3,...) are sufficiently close in time that two successive portions (P1,P2,P3,...) of predetermined length Lp have a plurality of cross-sectional profiles (PT1,PT2,PT3,...) in common.
4. Cutting method according to claim 3, wherein two successive portions (P1,P2,P3,...) have between 3% and 10% of cross profiles (PT1,PT2,PT3,...) in common.
5. Cutting method according to any one of the preceding claims, wherein, during step a) and for the purpose of carrying out step b), the imaging device captures between 1000 and 1800, preferably between 1300 and 1500, cross profiles (PT1,PT2,PT3,...) in a portion (P1,P2,P3,...) of predetermined length Lp.
6. Cutting method according to any one of the preceding claims, wherein the predetermined length Lp of a portion (P1,P2,P3,...) of the reinforced sheet in which the plurality of successive cross profiles (PT1,PT2,PT3,...) is captured is between 15 and 25 cm, preferably between 18 and 22 cm.
7. A cutting method according to any one of the preceding claims, wherein 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 any one of the preceding claims, wherein the width of a selvage between its cut edge and the last reinforcing wire present in this selvage is between 150 and 250 pm.
9. A cutting method according to any one of the preceding claims, wherein the reinforced sheet passes continuously under the imaging device at a speed greater than 50 m / min, and for example greater than 100 m / min.
10. 111111. Cutting method according to any one of the preceding claims, wherein the imaging device used in step a) is a profilometer with a resolution of at least 10 pm and a field length of less than or equal to 40 mm.