EP4087970B1 - Single-layer multi-strand cable having improved energy at break and an improved total elongation - Google Patents

Description

The invention relates to cables, a reinforced product and a tire comprising these cables.

We know the state of the art, in particular the document WO2016/131862 a pneumatic tire for civil engineering vehicles with a radial carcass reinforcement comprising a tread, two inextensible beads, two sidewalls connecting the beads to the tread and a crown reinforcement, arranged circumferentially between the carcass reinforcement and the tread. This crown reinforcement comprises several plies reinforced by reinforcing elements such as metal cables, the cables of a ply being embedded in an elastomeric matrix of the ply.

The state of the art of the document is also known EP0376272 relating to cables with a 1 × N structure.

The top reinforcement includes a working reinforcement, a protective reinforcement and possibly other reinforcements, for example a hoop reinforcement.

The protective reinforcement comprises one or more protective plies comprising several protective reinforcing wire elements. Each protective reinforcing wire element is a cable having a 1xN structure. The cable comprises a single layer of N=4 strands wound in a helix at a pitch p3=20 mm. Each strand comprises, on the one hand, an inner layer of M=3 inner wires wound in a helix at a pitch p1=6.7 mm and an outer layer of V=8 outer wires wound in a helix around the inner layer at a pitch p2=10 mm. Each inner and outer wire has a diameter equal to 0.35 mm and the total elongation of the cable is 6%.

On the one hand, when the tire passes over obstacles, for example in the form of stones, these obstacles risk perforating the tire until they reach the crown reinforcement. These perforations allow corrosive agents to enter the crown reinforcement of the tire and reduce its service life.

On the other hand, it has been observed that the cables of the protective layers can present ruptures following deformations and relatively significant forces exerted on the cable, in particular when the tire passes over obstacles.

The invention aims to provide a cable making it possible to reduce, or even eliminate, the number of breakages and the number of perforations.

• le câble présente un allongement total At >8,10 % déterminé par la norme ASTM D2969-04 de 2014 ; et
• l'indicateur d'énergie à rupture Er du câble défini par $\mathit{Er}={\displaystyle {\int }_0^{\mathit{At}}\sigma \left(\mathit{Ai}\right)}\times \mathit{dAi}$
  
  avec σ(Ai) étant la contrainte de traction en MPa mesurée à l'allongement Ai et dAi étant l'allongement tel que Er est strictement supérieur à 52 MJ/m³.

For this purpose, the invention relates to a multi-strand cable having a 1xN structure comprising a single layer of N strands wound in a helix around a main axis (A), each strand having a layer of metal wires and comprising M>1 metal wires wound in a helix around an axis (B), in which:

• the cable has a total elongation At >8.10% determined by ASTM D2969-04 of 2014; and
• the breaking energy indicator Er of the cable defined by $\mathit{Er}={\displaystyle {\int }_0^{\mathit{At}}\sigma \left(\mathit{Have}\right)}\times \mathit{dAi}$
  
  with σ ( Ai ) being the tensile stress in MPa measured at elongation Ai and dAi being the elongation such that Er is strictly greater than 52 MJ/m ³ .

Thanks to the relatively high total elongation and the relatively high breaking energy of the cable, the cable according to the invention makes it possible to reduce perforations and therefore to extend the service life of the tire. Indeed, the inventors behind the invention discovered that a less rigid cable than that of the prior art is more efficient against obstacles. The inventors found that it was more effective to hug the obstacle using a cable having less rigidity rather than trying to stiffen and reinforce the cables as much as possible to oppose the deformations imposed by the obstacles as is generally taught in the prior art. By hugging the obstacles, the force opposing the obstacles is reduced and therefore the risk of puncturing the tire. This effect of reducing rigidity is illustrated in figure 7 where under stress the cable according to the invention exhibits good deformability under low load thanks to the radial play of the wires.

Thanks to the relatively high total elongation, to the relatively high breaking energy of the cable, the cable according to the invention also makes it possible to reduce the number of breakages. Indeed, the inventors at the origin of the invention discovered that the determining criterion for reducing cable breakages was not only the breaking force as is widely taught in the state of the art but the breaking energy indicator represented in the present application by the area under the stress curve as a function of the elongation as illustrated in part on the figure 4 . Indeed, the cables of the prior art have either a relatively high breaking force but a relatively low breaking elongation, or a relatively high breaking elongation but a relatively low breaking force. In both cases, the cables of the prior art break under a relatively low breaking energy indicator. The cable according to the invention, due to its relatively high total elongation, has a necessarily relatively high breaking elongation. Synergistically, the relatively low modulus makes it possible to push back the breaking elongation due to a relatively low slope of the stress-elongation curve in the elastic range. Finally and above all, the inventors have discovered that the increase in the total elongation makes it possible, as demonstrated by the comparative tests below, on the one hand, to push back the breaking elongation and therefore to increase the stress, which makes it possible to increase the breaking energy.

Any interval of values denoted by the expression "between a and b" represents the domain of values from greater than a to less than b (i.e., excluding limits a and b) while that any interval of values designated by the expression "from a to b" means the domain of values extending from the limit "a" to the limit "b" i.e. including the strict limits "a" and "b".

The total elongation At, a quantity well known to those skilled in the art, is determined for example by applying the ASTM D2969-04 standard of 2014 to a cable tested so as to obtain a stress-elongation curve. The At is deduced on the curve obtained as the elongation, in %, corresponding to the projection on the elongation axis of the breaking point of the cable on the stress-elongation curve, i.e. the point at which the load increases to a maximum stress value and then decreases abruptly after rupture. When the decrease in relation to the stress exceeds a certain threshold, this means that the cable has ruptured.

. Cet indicateur d'énergie à rupture représente une densité volumique d'énergie en MJ/m³. La méthode des rectangles est classiquement employée pour atteindre cette aire : la contrainte de traction sigma(Ai) étant exprimée en MPa mesurée à l'allongement Ai exprimé en % sans unité ; pour i=0 : Ai=0 = A0 = 0% d'allongement et pour i=t : Ai=t = At : allongement à rupture totale du câble. L'indicateur d'énergie à rupture Er est ainsi la somme de (1/2( σ(Ai) + σ(Ai+1)) x (Ai+1 - Ai) pour i allant de 0 à t. Pour cette intégration, l'échantillonnage des rectangles est défini de telle sorte que les largeurs définies par (Ai+1 - Ai) sont sensiblement égales à 0.025% soit 4 rectangles pour 0.1% d'allongement tel que représenté sur la figure 4.The breaking energy indicator Er of the cable is determined by calculating the area under the stress-tensile curve as a function of elongation by the relation $\mathit{Er}={\displaystyle {\int }_0^{\mathit{At}}\sigma \left(\mathit{Have}\right)\times \mathit{dAi}}$

. This breaking energy indicator represents a volumetric energy density in MJ/m ³ . The rectangle method is conventionally used to reach this area: the tensile stress sigma(Ai) being expressed in MPa measured at the elongation Ai expressed in % without unit; for i=0: Ai=0 = A0 = 0% elongation and for i=t: Ai=t = At: elongation at total rupture of the cable. The breaking energy indicator Er is thus the sum of (1/2( σ(Ai) + σ(Ai+1)) x (Ai+1 - Ai) for i ranging from 0 to t. For this integration, the sampling of the rectangles is defined such that the widths defined by (Ai+1 - Ai) are substantially equal to 0.025% or 4 rectangles for 0.1% elongation as shown in the figure 4 .

In the invention, the cable comprises a single layer of N strands, that is to say it comprises an assembly consisting of one layer of strands, no more and no less, that is to say the assembly has one layer of strands, not zero, not two, but only one.

Advantageously, the winding direction of each strand is opposite to the winding direction of the cable.

The winding direction of a layer of strands means the direction formed by the strands relative to the axis of the cable. The winding direction is commonly designated by the letter either Z or S.

Strand winding directions are determined in accordance with ASTM D2969-04 of 2014.

The cable according to the invention is single helix. By definition, a single helix cable is a cable in which the axis of each strand of the layer describes a single helix around a main axis, unlike a double helix cable in which the axis of each strand describes a first helix around the axis of the cable and a second helix around a helix described by the axis of the cable. In other words, when the cable extends in a direction substantially straight, the cable comprises a single layer of strands wound together in a helix, each strand of the layer describing a helical trajectory around a main axis substantially parallel to the substantially straight direction such that, in a section plane substantially perpendicular to the main axis, the distance between the center of each strand of the layer and the main axis is substantially constant and equal for all the strands of the layer. In contrast, when a double helix cable extends in a substantially straight direction, the distance between the center of each strand of the layer and the substantially straight direction is different for all the strands of the layer.

In the same way as described above for the cable, each strand according to the invention is single-helix. By definition, a single-helix strand is a strand in which the axis of each metal wire element of the layer describes a single helix, unlike a double-helix strand in which the axis of each metal wire element describes a first helix around the axis of the strand and a second helix around a helix described by the axis of the strand. In other words, when the strand extends in a substantially rectilinear direction, the strand comprises a single layer of metal wire elements wound together in a helix, each metal wire element of the layer describing a helix-shaped trajectory around a main axis substantially parallel to the substantially rectilinear direction such that, in a section plane substantially perpendicular to the main axis, the distance between the center of each metal wire element of the layer and the main axis is substantially constant and equal for all the metal wire elements of the layer. Conversely, when a double helix strand extends in a substantially straight direction, the distance between the center of each wire element in the layer and the substantially straight direction is different for all wire elements in the layer.

The cable according to the invention is devoid of a central metal core. It is also referred to as a 1xN structure cable in which N is the number of strands or even an open-cord cable. In the cable according to the invention defined above, the internal arch is empty and therefore devoid of any filling material, in particular devoid of any elastomeric composition. It is then referred to as a cable devoid of filling material.

By wire element is meant an element extending longitudinally along a main axis and having a section perpendicular to the main axis whose largest dimension G is relatively small compared to the dimension L along the main axis. By relatively small is meant that L/G is greater than or equal to 100, preferably greater than or equal to 1000. This definition covers both wire elements of circular section and wire elements of non-circular section, for example of polygonal or oblong section. Very preferably, each metal wire element has a circular section.

By definition, the term metallic means a wire element consisting mainly (i.e. for more than 50% of its mass) or entirely (for 100% of its mass) of a metallic material. Each metallic wire element is preferably made of steel, more preferably of pearlitic or ferrito-pearlitic carbon steel, commonly called carbon steel by those skilled in the art, or even of stainless steel (by definition, steel containing at least 10.5% chromium).

Preferably, the metal wires and strands do not undergo preforming. In other words, the cable is obtained by a process devoid of individual preforming steps of each of the metal wire elements and each of the strands.

Advantageously, the total elongation At ≥ 8.30% and preferably At ≥ 8.50%.

Advantageously, the total elongation At ≤ 20.00% and preferably At ≤ 16.00%.

Advantageously, the breaking energy indicator Er of the cable (50) is greater than or equal to 55 MJ/m ³ .

Preferably, the breaking energy indicator Er of the cable (50) is less than or equal to 200 MJ/m ³ and preferably less than or equal to 150 MJ/m ³ .

Preferably, the cable has a structural elongation As determined by ASTM D2969-04 of 2014 such that As > 4.30%, preferably As ≥ 4.50% and more preferably As ≥ 4.60%.

Preferably, the cable has a structural elongation As determined by ASTM D2969-04 of 2014 such that As ≤ 10.0% and preferably As ≤ 9.50%.

The structural elongation As, a quantity well known to those skilled in the art, is determined for example by applying the ASTM D2969-04 standard of 2014 to a cable tested so as to obtain a force-elongation curve. The As is deduced on the curve obtained as the elongation, in %, corresponding to the projection on the elongation axis of the intersection between the tangent to the structural part of the force-elongation curve and the tangent to the elastic part of the force-elongation curve. As a reminder, a force-elongation curve comprises, moving towards increasing elongations, a structural part, an elastic part and a plastic part. The structural part corresponds to the structural elongation As resulting from the aeration of the cable, i.e. the vacant space between the different metal strands constituting the cable. The elastic part corresponds to an elastic elongation resulting from the construction of the cable, in particular the angles of the different layers and the diameters of the strands. The plastic part corresponds to the plastic elongation resulting from the plasticity (irreversible deformation beyond the elastic limit) of one or more metallic wire elements of the strands.

Preferably, the cable has a secant modulus E1 ranging from 3.0 to 10.0 GPa and preferably ranging from 3.5 to 8.5 GPa.

The cable according to the invention can thus have significant deformation at low force and a first low rigidity.

The secant modulus E1 is the slope of the line connecting the origin of the stress-elongation curve obtained under the conditions of the ASTM D 885/D 885M - 10a standard of 2014 to the abscissa point 1% of this same curve.

Preferably, the cable has a tangent modulus E2 ranging from 50 to 180 GPa and preferably from 55 to 150 GPa.

Thus, the cable according to the invention has a minimum rigidity to allow the recovery or transmission of force.

The tangent modulus E2 is calculated as follows on the stress-strain curve obtained under the conditions of ASTM D 885/D 885M - 10a of 2014: E2 corresponds to the maximum tangent modulus of the cable on the force-strain curve.

• le câble extrait (50') présente un allongement total At' ≥ 5,00 % déterminé par la norme ASTM D2969-04 de 2014,
• l'indicateur d'énergie à rupture Er' du câble extrait (50') défini par $\mathit{Er}\prime ={\displaystyle {\int }_0^{\mathit{At}\prime }\sigma \left(\mathit{Ai}\right)}\times \mathit{dAi}$
  
  avec σ(Ai) étant la contrainte de traction en MPa mesurée à l'allongement Ai et dAi étant l'allongement tel que Er' est strictement supérieur à 35 MJ/m³.

The invention also relates to a cable extracted from a polymer matrix, the extracted cable having a 1xN structure comprising a single layer of N strands wound in a helix around a main axis (A), each strand having a layer of metal wires and comprising M>1 metal wires wound in a helix around an axis (B), in which:

• the extracted cable (50') has a total elongation At' ≥ 5.00% determined by ASTM D2969-04 of 2014,
• the breaking energy indicator Er' of the extracted cable (50') defined by $\mathit{Er}\prime ={\displaystyle {\int }_0^{\mathit{At}\prime }\sigma \left(\mathit{Have}\right)}\times \mathit{dAi}$
  
  with σ ( Ai ) being the tensile stress in MPa measured at elongation Ai and dAi being the elongation such that Er' is strictly greater than 35 MJ/m ³ .

Preferably, the polymer matrix is an elastomeric matrix.

The polymeric matrix, preferably elastomeric, is based on a polymeric composition, preferably elastomeric.

By polymer matrix is meant a matrix comprising at least one polymer. The polymer matrix is thus based on a polymer composition.

By elastomeric matrix is meant a matrix comprising at least one elastomer. The preferred elastomeric matrix is thus based on the elastomeric composition.

By the expression "based on", it is meant that the composition comprises the mixture and/or the in situ reaction product of the different constituents used, some of these constituents being able to react and/or being intended to react with each other, at least partially, during the different phases of manufacture of the composition; the composition thus being able to be in a totally or partially crosslinked state or in a non-crosslinked state.

By polymeric composition is meant that the composition comprises at least one polymer. Preferably, such a polymer may be a thermoplastic, for example a polyester or a polyamide, a thermosetting polymer, an elastomer, for example natural rubber, a thermoplastic elastomer or a mixture of these polymers

By elastomeric composition is meant that the composition comprises at least one elastomer and at least one other component. Preferably, the composition comprising at least one elastomer and at least one other component comprises an elastomer, a crosslinking system and a filler. The compositions that can be used for these sheets are conventional compositions for calendering reinforcing wire elements and comprise a diene elastomer, for example natural rubber, a reinforcing filler, for example carbon black and/or silica, a crosslinking system, for example a vulcanization system, preferably comprising sulfur, stearic acid and zinc oxide, and optionally a vulcanization accelerator and/or retarder and/or various additives. The adhesion between the metal wires and the matrix in which they are embedded is ensured for example by a metal coating, for example a layer of brass.

The values of the characteristics described in the present application for the extracted cable are measured on or determined from cables extracted from a polymer matrix, in particular an elastomeric matrix, for example from a tire. Thus, for example on a tire, the strip of material is removed radially outside the cable to be extracted so as to see the cable to be extracted radially flush with the polymer matrix. This removal can be done by peeling using pliers and knives or by planing. Then, the end of the cable to be extracted is released using a knife. Then, the cable is pulled so as to extract it from the matrix by applying a relatively small angle so as not to plasticize the cable to be extracted. The extracted cables are then carefully cleaned, for example using a knife, so as to detach the remains of polymer matrix locally attached to the cable and taking care not to damage the surface of the metal wires.

Preferably, the total elongation At' is such that At' ≥ 5.20%.

Preferably, the breaking energy indicator Er' of the cable (50) is greater than or equal to 40 MJ/m ³ .

The advantageous characteristics described below apply equally to the cable as defined above and to the extracted cable.

Advantageously, the cable is such that the strands define an internal arch of the cable of diameter Dv, each strand having a diameter Dt and a helix curvature radius Rt defined by Rt=Pe/(π x Sin(2αe)) with Pe the pitch of each strand expressed in millimeters and αe the helix angle of each strand (54), in which Dv, Dt and Rt being expressed in millimeters: 25 ≤ Rt / Dt ≤ 180 and 0.10 ≤ Dv / Dt ≤ 0.50.

The cable according to the invention has excellent longitudinal compressibility and, all things being equal, a relatively small diameter.

On the one hand, the inventors behind the invention hypothesize that, because of a sufficiently high radius of curvature Rt relative to the diameter Dt of each strand, the cable is sufficiently ventilated, thus reducing the risk of buckling, due to the relatively large distance of each strand from the longitudinal axis of the cable, a distance allowing the strands to accommodate, by their helix, relatively high longitudinal compressive deformations. On the contrary, the radius of curvature Rt of each strand of the cable of the prior art being relatively small relative to the diameter Dt, the metal wire elements are closer to the longitudinal axis of the cable and can accommodate, by their helix, much lower longitudinal compressive deformations than the cable according to the invention.

On the other hand, for a radius of curvature Rt of each strand that is too high, the cable according to the invention would have insufficient longitudinal rigidity in compression to ensure a reinforcement role, for example of tires.

Furthermore, for an internal arch diameter Dv that is too high, the cable would have, relative to the diameter of the strands, a diameter that is too high.

The values of the characteristics Dt, Dv and Rt as well as the other characteristics described below are measured on or determined from the cables either directly after manufacture, i.e. before any step of embedding in an elastomeric matrix, or extracted from an elastomeric matrix, for example from a tire, and having then undergone a cleaning step during which any elastomeric matrix is removed from the cable, in particular any material present inside the cable. To guarantee an original state, the adhesive interface between each metal wire element and the elastomeric matrix must be removed, for example by electrochemical process in a sodium carbonate bath. The effects associated with the shaping step of the tire manufacturing process described below, in particular the elongation of the cables, are cancelled by the extraction of the ply and the cable which, during extraction, substantially regain their characteristics from before the shaping step.

The arch of the cable according to the invention is delimited by the strands and corresponds to the volume delimited by a theoretical circle, on the one hand, radially inside each strand and, on the other hand, tangent to each strand. The diameter of this theoretical circle is equal to the arch diameter Dv.

The helix angle of each strand αe is a quantity well known to those skilled in the art and can be determined by the following calculation: tan αe = 2xπ x Re/Pe, formula in which Pe is the pitch expressed in millimeters in which each strand is wound, Re is the helix radius of each strand expressed in millimeters, and tan denotes the tangent function. αe is expressed in degrees.

The helix diameter De, expressed in millimeters, is calculated according to the relation De=Pe x Tan(αe) / π in which Pe is the pitch expressed in millimeters at which each strand is wound, αe is the helix angle of each strand determined above and Tan the tangent function. The helix diameter De corresponds to the diameter of the theoretical circle passing through the centers of the strands of the layer in a plane perpendicular to the main axis of the cable.

The arch diameter Dv, expressed in millimeters, is calculated according to the relation Dv=De-Dt in which Dt is the diameter of each strand and De the helix diameter, both expressed in millimeters.

The radius of curvature Rt, expressed in millimeters, is calculated according to the relation Rt=Pe/(π x Sin(2αe)) in which Pe is the pitch expressed in millimeters of each strand, αe is the helix angle of each strand and Sin the sine function.

It is recalled that the pitch at which each strand is wound is the length travelled by this wire element, measured parallel to the axis of the cable in which it is located, at the end of which strand having this pitch makes a complete turn around said axis of the cable.

Advantageously, the cable is such that the metal wire elements define an internal arch of the strand of diameter Dvt, each metal wire element having a diameter Df and a helix curvature radius Rf defined by Rf=P/(π x Sin(2α)) with P the pitch of each metal wire element expressed in millimeters and α the helix angle of each metal wire element (F1), Dvt, Df and Rf being expressed in millimeters, the cable satisfying the following relationships: 9 ≤ Rf / Df ≤ 30, and 1.30 ≤ Dvt / Df ≤ 4.50.

The arch of each strand is delimited by the metal wires and corresponds to the volume delimited by a theoretical circle, on the one hand, radially inside each metal wire element and, on the other hand, tangent to each metal wire element. The diameter of this theoretical circle is equal to the arch diameter Dvt.

The helix angle of each wire element α is a quantity well known to those skilled in the art and can be determined by the following calculation: tan α = 2xπ x R/P, formula in which P is the pitch expressed in millimeters in which each strand is wound, R is the helix radius of each strand expressed in millimeters, and tan denotes the tangent function. α is expressed in degrees.

The helix diameter Dh, expressed in millimeters, is calculated according to the relation Dh=P x Tan(α) / π in which P is the pitch expressed in millimeters at which each wire element is wound, α is the helix angle of each wire element determined above and Tan is the tangent function. The helix diameter Dh corresponds to the diameter of the theoretical circle passing through the centers of the wire elements of the layer in a plane perpendicular to the main axis of the cable.

The arch diameter of the strand Dvt, expressed in millimeters, is calculated according to the relation Dvt=Dh-Df in which Df is the diameter of each wire element and Dh the helix diameter, both expressed in millimeters.

The radius of curvature Rf, expressed in millimeters, is calculated according to the relation Rf=P/(π x Sin(2α)) in which P is the pitch expressed in millimeters of each wire element, α is the helix angle of each wire element and Sin the sine function.

It is recalled that the pitch at which each metallic wire element is wound is the length travelled by this wire element, measured parallel to the axis of the cable in which it is located, at the end of which the wire element having this pitch makes a complete turn around said axis of the cable.

The optional features described below may be combined with each other to the extent that such combinations are technically compatible.

In an advantageous embodiment, all the metal wire elements have the same diameter Df.

• une étape de fabrication de N torons par :
  • une étape de fourniture d'un assemblage transitoire comprenant une couche constituée de M'>1 fils métalliques enroulés en hélice autour d'un noyau transitoire ;
  • une étape de séparation de l'assemblage transitoire entre :
    • un premier assemblage fractionné comprenant une couche constituée de M1'≥1 fil(s) métallique(s) enroulé(s) en hélice, le ou les M1' fil(s) métallique(s) étant issu(s) de la couche constituée de M'>1 fils métalliques de l'assemblage transitoire ,
    • un deuxième assemblage fractionné comprenant une couche constituée de M2'>1 fils métalliques enroulés en hélice, les M2' fils métalliques étant issus de la couche constituée de M'>1 fils métalliques de l'assemblage transitoire ,
    • le noyau transitoire ou un ou plusieurs ensembles comprenant le noyau transitoire ,
    • une étape de réassemblage du premier assemblage fractionné avec le deuxième assemblage fractionné pour former un toron à une couche de fils métalliques et comprenant M>1 fils métalliques ;
    • une étape d'assemblage des N torons par câblage pour former le câble.

The invention also relates to a method of manufacturing a cable comprising:

• a manufacturing step of N strands by:
  • a step of providing a transient assembly comprising a layer consisting of M'>1 metal wires wound in a helix around a transient core;
  • a step of separation of the transient assembly between:
    • a first split assembly comprising a layer consisting of M1'≥1 metal wire(s) wound in a helix, the M1' metal wire(s) coming from the layer consisting of M'>1 metal wires of the transitional assembly,
    • a second split assembly comprising a layer consisting of M2'>1 metal wires wound in a helix, the M2' metal wires being derived from the layer consisting of M'>1 metal wires of the transitional assembly,
    • the transient core or one or more sets comprising the transient core,
    • a step of reassembling the first split assembly with the second split assembly to form a single-layer strand of metal wires and comprising M>1 metal wires;
    • a step of assembling the N strands by cabling to form the cable.

Each strand is manufactured in accordance with a process and using an installation described in the documents WO2016083265 And WO2016083267 . Such a method implementing a splitting step is to be distinguished from a conventional wiring method comprising a single assembly step in which the metal wire elements are wound in a helix, the assembly step being preceded by a step of individual preforming of each metal wire element in order in particular to increase the value of the structural elongation. Such methods and installations are described in the documents EP0548539 , EP1000194 , EP0622489 , WO2012055677 , JP2007092259 , WO2007128335 , JPH06346386 or even EP0143767 . In these processes, in order to obtain the highest possible structural elongation, the metal monofilaments are individually preformed. However, this step of individual preforming of the monofilaments metallic, which requires a special installation, on the one hand, makes the process relatively unproductive compared to a process without an individual preforming step without however allowing high structural elongations to be achieved and, on the other hand, alters the metallic monofilaments thus preformed due to friction with the preforming tools. Such alteration creates incipient breaks on the surface of the metallic monofilaments and is therefore detrimental to the endurance of the metallic monofilaments, in particular to their endurance in compression. The absence or presence of such preforming marks can be observed under an electron microscope at the end of the manufacturing process, or more simply, by knowing the manufacturing process of the cable.

Due to the method used, each wire element of the cable is free of pre-forming marks. Such pre-forming marks include, in particular, flats. The pre-forming marks also include cracks extending in cutting planes substantially perpendicular to the main axis along which each wire element extends. Such cracks extend, in a cutting plane substantially perpendicular to the main axis, from a radially external surface of each wire element radially towards the inside of each wire element. As described above, such cracks are initiated by the mechanical pre-forming tools due to bending forces, i.e. perpendicular to the main axis of each wire element, which makes them very detrimental to endurance. Conversely, in the method described in WO2016083265 And WO2016083267 in which the wire elements are collectively and simultaneously preformed on a transient core, the preforming forces are exerted in torsion and therefore not perpendicular to the main axis of each wire element. Any cracks created do not extend radially from the radially external surface of each wire element radially towards the inside of each wire element but along the radially external surface of each wire element which makes them not very detrimental to endurance.

Advantageously, the cable has a diameter D such that D ≤ 6.00 mm and preferably D ≤ 5.00 mm.

The diameter or apparent diameter, noted D, is measured by wedging the cable between two perfectly straight bars of length 200 mm and by measuring the spacing in which the cable is embedded using the comparator described below. We can cite for example the model JD50/25 of the KAEFER brand allowing to reach a precision of 1/100 of a millimeter, equipped with type a touch, and having a contact pressure close to 0.6N. The measurement protocol consists of three repetitions of a series of three measurements (carried out perpendicular to the axis of the cable and under zero tension)

In one embodiment, each wire element comprises a single metal monofilament. Here, each metal wire element is advantageously made of a metal monofilament. In a variant of this embodiment, the metal monofilament is directly coated with a layer of a metal coating comprising copper, zinc, tin, cobalt or an alloy of these metals, for example brass or bronze. In this variant, each metal wire element is then made of the metal monofilament, for example steel, forming a core, directly coated with the layer of metal coating.

In this embodiment, each elementary metal monofilament is, as described above, preferably made of steel, and has a mechanical strength ranging from 1000 MPa to 5000 MPa. Such mechanical strengths correspond to the steel grades commonly encountered in the field of tires, namely, the grades NT (Normal Tensile), HT (High Tensile), ST (Super Tensile), SHT (Super High Tensile), UT (Ultra Tensile), UHT (Ultra High Tensile) and MT (Mega Tensile), the use of high mechanical strengths possibly allowing improved reinforcement of the matrix in which the cable is intended to be embedded and a lightening of the matrix thus reinforced.

Advantageously, the layer is made up of N strands wound in a helix, N ranging from 2 to 6.

The assembly process of the N strands is implemented by cabling. By cabling, we mean that the strands do not undergo torsion around their own axis, due to a synchronous rotation before and after the assembly point. This has the main advantage of increasing the ductility of the cables but also of achieving a greater breaking force than that of opencord strands alone.

In a first embodiment allowing partial reassembly of the M' metallic wire elements, the separation step and the reassembly step are carried out so that M1'+M2'<M'.

In a second embodiment allowing a total reassembly of the M' metallic wire elements, the separation step and the reassembly step are carried out so that M 1'+M2'=M'.

The advantageous characteristics described below apply equally to the method of the first and second modes as defined above.

Preferably, M= M1'+M2' ranges from 3 to 18 and preferably from 4 to 15.

• M1'=1, 2 ou 3 et M2'=1,2 ou 3 dans les cas où M'=4 ou M'=5 et
• M1' ≤ 0,75 x M' dans les cas où M'≥6.
• M2' ≤ 0,75 x M' dans les cas où M'≥6.

Advantageously, in order to facilitate the exit of the transient core in the embodiments in which the transient core is separated into two parts each going with the first and second split assemblies:

• M1'=1, 2 or 3 and M2'=1,2 or 3 in cases where M'=4 or M'=5 and
• M1' ≤ 0.75 x M' in cases where M'≥6.
• M2' ≤ 0.75 x M' in cases where M'≥6.

In order to further facilitate the exit of the transient core in embodiments in which the transient core is separated into two parts each going with the first and second assemblies in cases where M'≥6, M1' ≤ 0.70 x M' and M2' ≤ 0.70 x M'.

Very preferably, the step of providing the transient assembly comprises a step of assembly by twisting the M'>1 metallic wire elements wound in a helix around the transient core.

Advantageously, the step of providing the transient assembly comprises a step of balancing the transient assembly. Thus, the balancing step being carried out on the transient assembly comprising the M'metal wire elements and the transient core, the balancing step is implicitly carried out upstream of the step of separation between the first and second split assemblies. It is avoided to have to manage the residual twist imposed during the step of assembling the transient assembly during the path of the different assemblies downstream of the assembly step, in particular in the guide means, for example the pulleys.

Advantageously, the method comprises a step of balancing the final assembly downstream of the reassembly step.

Advantageously, the method comprises a step of maintaining the rotation of the final assembly around its running direction. This rotation maintenance step is carried out downstream of the step of separating the transient assembly and upstream of the step of balancing the final assembly.

Preferably, the method is free of individual preforming steps for each of the wire elements. In the methods of the prior art using an individual preforming step for each of the wire elements, the latter are given a shape by preforming tools, for example rollers, these tools creating defects on the surface of the wire elements. These defects significantly reduce the endurance of the wire elements and therefore of the final assembly.

Very preferably, the transitional core is a metal wire element. In a preferred embodiment, the transitional core is a metal monofilament. Thus, the diameter of the space between the metal wire elements and therefore the geometric characteristics of the final assembly are very precisely controlled, unlike a transitional core made of a textile material, for example polymeric, the compressibility of which can cause variations in the geometric characteristics of the final assembly.

In other equally advantageous embodiments, the transitional core is a textile filament element. Such a textile filament element comprises at least one multifilament textile strand or, alternatively, is made of a textile monofilament. The filaments textiles that can be used are chosen from polyesters, polyketones, aliphatic or aromatic polyamides and mixtures of textile filaments of these materials. This reduces the risks of breakage of the transitional core caused by friction of the metal wire elements on the transitional core as well as by the twists imposed on the transitional core.

REINFORCED PRODUCT ACCORDING TO THE INVENTION

The invention also relates to a reinforced product comprising a polymer matrix and at least one extracted cable as defined above.

Advantageously, the reinforced product comprises one or more cables according to the invention embedded in the polymer matrix, and in the case of several cables, the cables are arranged side by side in a main direction.

PNEUMATIC ACCORDING TO THE INVENTION

The invention also relates to a tire comprising at least one extracted cable as defined above or a reinforced product as defined above.

Preferably, the tire comprises a carcass reinforcement anchored in two beads and surmounted radially by a crown reinforcement itself surmounted by a tread, the crown reinforcement being joined to said beads by two sidewalls and comprising at least one cable as defined above.

In a preferred embodiment, the crown reinforcement comprises a protective reinforcement and a working reinforcement, the working reinforcement comprising at least one cable as defined above, the protective reinforcement being radially interposed between the tread and the working reinforcement.

The cable is particularly intended for industrial vehicles selected from heavy vehicles such as "Heavy goods vehicles" - i.e., metro, bus, road transport vehicles (trucks, tractors, trailers), off-road vehicles -, agricultural or civil engineering vehicles, other transport or handling vehicles.

Preferably, the tire is for civil engineering type vehicles. Thus, the tire has a dimension in which the diameter, in inches, of the seat of the rim on which the tire is intended to be mounted is greater than or equal to 30 inches.

The invention also relates to a rubber article comprising an assembly according to the invention, or an impregnated assembly according to the invention. By rubber article is meant any type of rubber article such as a ball, a non-pneumatic object such as a non-pneumatic tire, a conveyor belt or a caterpillar.

• la figure 1 est une vue en coupe perpendiculaire à la direction circonférentielle d'un pneumatique selon l'invention ;
• la figure 2 est une vue de détails de la zone II de la figure 1 ;
• la figure 3 est une vue en coupe d'un produit renforcé selon l'invention ;
• la figure 4 illustre une partie de la courbe contrainte-allongement d'un câble (50) selon l'invention ;
• la figure 5 est une vue schématique en coupe perpendiculaire à l'axe du câble (supposé rectiligne et au repos) d'un câble (50) selon un premier mode de réalisation de l'invention ;
• la figure 6 est une vue analogue à celle de la figure 5 d'un câble (60) selon un deuxième mode de réalisation l'invention ;
• la figure 7 est une représentation schématique de l'effet de la déformabilité du câble (50) de la figure 5 sous faible charge de traction grâce au jeu radial des fils ;

et les figures 8 et 9 sont des représentations schématiques du procédé selon l'invention permettant de fabriquer le câble (50) de la figure 5.The invention will be better understood from reading the examples which follow, given solely as non-limiting examples and made with reference to the drawings in which:

• there figure 1 is a sectional view perpendicular to the circumferential direction of a pneumatic according to the invention;
• there figure 2 is a detailed view of zone II of the figure 1 ;
• there figure 3 is a sectional view of a reinforced product according to the invention;
• there figure 4 illustrates a portion of the stress-strain curve of a cable (50) according to the invention;
• there figure 5 is a schematic sectional view perpendicular to the axis of the cable (assumed to be straight and at rest) of a cable (50) according to a first embodiment of the invention;
• there figure 6 is a view similar to that of the figure 5 of a cable (60) according to a second embodiment of the invention;
• there figure 7 is a schematic representation of the effect of the deformability of the cable (50) of the figure 5 under low tensile load thanks to the radial play of the wires;

and the Figures 8 And 9 are schematic representations of the method according to the invention for manufacturing the cable (50) of the figure 5 .

EXAMPLE OF A TIRE ACCORDING TO THE INVENTION

In the Figures 1 and 2 , we have represented a reference X, Y, Z corresponding to the usual orientations respectively axial (X), radial (Y) and circumferential (Z) of a tire.

The “median circumferential plane” M of the tire is the plane which is normal to the axis of rotation of the tire and which is located equidistant from the annular reinforcement structures of each bead.

It has been represented on the Figures 1 and 2 a tire according to the invention and designated by the general reference P.

The P tire is for heavy civil engineering type vehicles, for example “dumper” type. Thus, the P tire has a dimension of type 53/80R63.

The tire P comprises a crown 12 reinforced by a crown reinforcement 14, two sidewalls 16 and two beads 18, each of these beads 18 being reinforced with an annular structure, here a bead wire 20. The crown reinforcement 14 is radially surmounted by a tread 22 and joined to the beads 18 by the sidewalls 16. A carcass reinforcement 24 is anchored in the two beads 18, and is here wound around the two bead wires 20 and comprises a turn-up 26 arranged towards the outside of the tire 20 which is here shown mounted on a rim 28. The carcass reinforcement 24 is radially surmounted by the crown reinforcement 14.

The carcass reinforcement 24 comprises at least one carcass ply 30 reinforced by radial carcass cords (not shown). The carcass cords are arranged substantially parallel to each other and extend from one bead 18 to the other so as to form an angle of between 80° and 90° with the median circumferential plane M (plane perpendicular to the axis of rotation of the tire which is located midway between the two beads 18 and passes through the middle of the crown reinforcement 14).

The tire P also comprises a sealing ply 32 made of an elastomer (commonly called inner rubber) which defines the radially internal face 34 of the tire P and which is intended to protect the carcass ply 30 from the diffusion of air coming from the space inside the tire P.

The crown reinforcement 14 comprises, radially from the outside to the inside of the tire P, a protective reinforcement 36 arranged radially inside the tread 22, a working reinforcement 38 arranged radially inside the protective reinforcement 36 and an additional reinforcement 40 arranged radially inside the working reinforcement 38. The protective reinforcement 36 is thus radially intercalated between the tread 22 and the working reinforcement 38. The working reinforcement 38 is radially intercalated between the protective reinforcement 36 and the additional reinforcement 40.

The protective frame 36 comprises first and second protective plies 42, 44 comprising protective metal cables, the first ply 42 being arranged radially inside the second ply 44. Optionally, the protective metal cables make an angle at least equal to 10°, preferably ranging from 10° to 35° and preferentially from 15° to 30° with the circumferential direction Z of the tire.

The working reinforcement 38 comprises first and second working plies 46, 48, the first ply 46 being arranged radially inside the second ply 48. Each ply 46, 48 comprises at least one cable 50. Optionally, the working metal cables 50 are crossed from one working ply to the other and make an angle at most equal to 60°, preferably ranging from 15° to 40° with the circumferential direction Z of the tire.

The additional frame 40, also called a limiter block, the function of which is to partially absorb the mechanical stresses of inflation, comprises, for example and in a manner known per se, additional metal reinforcement elements, for example as described in FR 2 419 181 Or FR 2 419 182 making an angle of at most 10°, preferably ranging from 5° to 10° with the circumferential direction Z of the tire P.

EXAMPLE OF A REINFORCED PRODUCT ACCORDING TO THE INVENTION

It was represented on the figure 3 a reinforced product according to the invention and designated by the general reference R. The reinforced product R comprises at least one 50' cable, in this case several 50' cables, embedded in the polymer matrix Ma.

On the figure 3 , the polymer matrix Ma, the cables 50' are represented in a reference frame X, Y, Z in which the direction Y is the radial direction and the directions X and Z are the axial and circumferential directions. On the figure 3 , the reinforced product R comprises several cables 50 arranged side by side in the main direction X and extending parallel to each other within the reinforced product R and collectively embedded in the matrix polymeric Ma.
Here, the polymer matrix Ma is an elastomeric matrix based on an elastomeric composition.

CABLE ACCORDING TO A FIRST EMBODIMENT OF THE INVENTION

It was represented on the figure 5 the cable 50 according to a first embodiment of the invention.

Each protective reinforcement element 43, 45 and each hoop reinforcement element 53, 55 is formed, after extraction of the tire 10, by an extracted cable 50' as described below. The cable 50 is obtained by embedding in a polymer matrix, in this case in a polymer matrix respectively forming each polymer matrix of each protective ply 42, 44 and of each hoop layer 52, 54 in which the protective reinforcement elements 43, 45 and hoop elements 53, 55 are respectively embedded.

The 50 cable and the 50' extracted cable are single-layer metallic.

The cable 50 or the cable 50' comprises a 1xN structure layer comprising a single layer 52 of N = 3 strands 54 wound helically around a main axis (A), each strand 54 being at a layer 56 of metal wires F1 and comprising M>1 metal wires wound helically around an axis (B), with here M=5.

As described previously, the At value is determined by plotting a stress-strain curve of the 50 cable using ASTM D2969-04 of 2014.

The cable 50 has a total elongation At > 8.10%, preferably At ≥ 8.30% and more preferably At ≥ 8.50% and the total elongation At ≤ 20.00% and preferably At ≤ 16.00%.here At=13.4%.

As described previously, from this stress-elongation curve, we deduce the area under this curve. We have represented on the figure 4 the rectangle method for determining the breaking energy indicator of cable 50.

qui est sensiblement égal à ${\displaystyle {\sum }_{0\%}^{\mathrm{13,4}\%}1/2\left(\mathrm{\sigma }\left(\mathrm{Ai}\right)+\mathrm{\sigma }\left(\mathrm{Ai}+1\right)\right)}\times \mathrm{0,025}\%=89\mathrm{MJ}/{\mathrm{m}}^3$

qui est strictement supérieur à 52 MJ/m³, de préférence supérieur ou égal à 55 MJ/m³et inférieur ou égal à 200 MJ/m³et de préférence inférieur ou égal à 150 MJ/m³.The breaking energy indicator Er of the cable 50 is such that $=\mathit{Er}={\displaystyle {\int }_0^{\mathit{At}}\sigma \left(\mathit{Have}\right)\times \mathit{dAi}}$

which is substantially equal to ${\displaystyle {\sum }_{0\%}^{13.4\%}1/2\left(\mathrm{\sigma }\left(\mathrm{Have}\right)+\mathrm{\sigma }\left(\mathrm{Have}+1\right)\right)}\times 0.025\%=89\mathrm{MJ}/{\mathrm{m}}^3$

which is strictly greater than 52 MJ/ ^m3 , preferably greater than or equal to 55 MJ/ ^m3 and less than or equal to 200 MJ/ ^m3 and preferably less than or equal to 150 MJ/ ^m3 .

The cable 50 has a structural elongation As such that As > 4.30%, preferably As ≥ 4.50% and more preferably As ≥ 4.60% and such that As ≤ 10.0% and preferably As ≤ 9.50%. Here As = 9.3%.

The cable 50 has a secant modulus E1 ranging from 3.0 to 10.0 GPa and preferably ranging from 3.5 to 8.5 GPa. Here E1 = 4.0 GPa
Cable 50 has a tangent modulus E2 ranging from 50 to 180 GPa and preferably from 55 to 150 GPa. Here E2=73 GPa.

The extracted 50' cable has a total elongation At' > 5.00% and preferably At' ≥ 5.20%. Here At'=10.0%.

qui est sensiblement égal à ${\displaystyle {\sum }_{0\%}^{\mathrm{10,0}\%}1/2\left(\mathrm{\sigma }\left(\mathrm{Ai}\right)+\mathrm{\sigma }\left(\mathrm{Ai}+1\right)\right)\times \mathrm{0,025}\%=82}$

MJ/m³ qui est strictement supérieur à 35 MJ/m³, de préférence supérieur ou égal à 40 MJ/m³.The breaking energy indicator Er' of the extracted cable 50' is such that Er' = ${\displaystyle {\int }_0^{\mathit{At}\prime }\sigma \left(\mathit{Have}\right)\times \mathit{dAi}}$

which is substantially equal to ${\displaystyle {\sum }_{0\%}^{10.0\%}1/2\left(\mathrm{\sigma }\left(\mathrm{Have}\right)+\mathrm{\sigma }\left(\mathrm{Have}+1\right)\right)\times 0.025\%=82}$

MJ/ ^m3 which is strictly greater than 35 MJ/ ^m3 , preferably greater than or equal to 40 MJ/ ^m3 .

$$\mathrm{Dv}/\mathrm{Dt}=\mathrm{0,32}/\mathrm{2,03}=\mathrm{0,16}\le \mathrm{0,50}\mathrm{et}\mathrm{0,16}\ge \mathrm{0,10}.$$

The strands 54 define an internal arch 59 of the cables 50; 50' of diameter Dv, each strand 54 having a diameter Dt and a helix curvature radius Rt defined by Rt=Pe/(π x Sin(2αe))= 80/(π x sin(2 x 5.3 x π /180)= 138 mm. $$\mathrm{Rt}/\mathrm{Dt}=138/2.03=68\le 180\mathrm{And}68\ge 25.$$

$$\mathrm{Dv}/\mathrm{Dt}=0.32/2.03=0.16\le 0.50\mathrm{And}0.16\ge 0.10.$$

$$\mathrm{Dvt}/\mathrm{Df}=\mathrm{1,12}/\mathrm{0,46}=\mathrm{2,46}\le \mathrm{4,50}\mathrm{et}\mathrm{2,46}\ge \mathrm{1,30}.$$

The metallic wire elements F1 of each strand 52 define an internal arch 58 of the strand 52 of diameter Dvt, each metallic wire element F1 has a diameter Df and a helix curvature radius Rf defined by Rf=P/(π x Sin(2α))= 10.4/(π x sin(2 x 25.8 x π /180)= 4.2 mm. $$\mathrm{Rf}/\mathrm{Df}=4.2/0.46=9\le 30.$$

$$\mathrm{Dvt}/\mathrm{Df}=1.12/0.46=2.46\le 4.50\mathrm{And}2.46\ge 1.30.$$

METHOD FOR MANUFACTURING THE CABLE ACCORDING TO THE INVENTION

We will now describe an example of a method of manufacturing the multi-strand cable 50 as shown in the Figures 8 And 9 .

First, the wire elements F1 and the transient core 16 are unwound from the supply means.

Then, the method comprises a step 100 of providing the transient assembly 22 comprising on the one hand a step of assembly by twisting the M' metallic wire elements F1 into a single layer of M' metallic wire elements F1 around the transient core 16 and on the other hand, a step of balancing the transient assembly 22 carried out using a finiister.

The method comprises a step 110 of separating the transient assembly 22 between the first split assembly 25, the second split assembly 27 and the transient core 16 or one or more assemblies comprising the transient core 16, here the transient core 16.

Downstream of the supply means 11, the step 110 of separating the transient assembly 22 between the first split assembly 25, the second split assembly 27 and the transient core 16 comprises a step 120 of separating the transient assembly 22 between the precursor assembly, the second split assembly 27 and finally the transient core 16.

Downstream of the separation step 122, the separation step 120 of the assembly transient between the precursor assembly and the split assembly comprises a step 124 of separating the split assembly between the second split assembly 27 and the transient core 16. Here, the separation step 124 comprises a step of splitting the split assembly into the second split assembly 27, the transient core 16 and the complementary assembly.

Downstream of the supply step 100, the step 110 of separating the transient assembly between the first split assembly 25, the second split assembly 27 and the transient core 16 comprises a step 130 of separating the precursor assembly between the first split assembly 25 and the complementary assembly.

Downstream of the separation steps 110, 120, 124 and 130, the method comprises a step 140 of reassembling the first split assembly 25 with the second split assembly 27 to form the strand 54. In this embodiment, the reassembly step 140 is a step of reassembling the first split assembly 25 with the second split assembly 27 to form the strand 54 and comprising M>1 metal wires F1, with M ranging from 3 to 18 and preferably from 4 to 15, here M=5.

In this embodiment, the supply step 100, the separation step 110 and the reassembly step 140 are carried out so that all the M' metallic wire elements F1 have the same diameter Df, are wound in a helix according to the same pitch P and have the same helix curvature radius Rf described previously.

In this embodiment allowing partial reassembly of the M' metallic wire elements, the separation step 110 and the reassembly step 140 are carried out so that M1'+M2'<M'. Here M1' =1 and M2'=4, M1'+M2'=5<8. Finally, it will be noted that M1' ≤ 0.70 x M' =0.70 x 8= 5.6 and M2' ≤ 0.70 x M' =0.70 x 8= 5.6.

A final balancing step is carried out.

Finally, strand 54 is stored on a storage reel. N strands 54 are manufactured in the same way.

Regarding the transient core 16, the method comprises a step of recycling the transient core 16. During this recycling step, the transient core 16 is recovered downstream of the separation step 110, here downstream of the separation step 124, and the transient core 16 recovered previously is introduced upstream of the assembly step. This recycling step is continuous.

It will be noted that the process thus described is devoid of individual pre-forming steps for each of the metallic wire elements F1.

We carry out a step 300 of assembling the N strands 54 by cabling to form the cable 50. Here N=3.

It will be noted that the method thus described is devoid of steps of individual pre-formation of each of the strands 54.

CABLE ACCORDING TO A SECOND EMBODIMENT OF THE INVENTION

It was represented on the figure 6 the cable 60 according to a second embodiment of the invention.

Unlike the first embodiment described above, the cable 60 according to the second embodiment is such that N = 4.

Tables 1, 2 and 3 below summarize the characteristics for the different cables 50, 50', 60, 60', 51, 52, 53, 53', 54 according to the invention and for the state-of-the-art cables EDT1, EDT1', EDT2 and EDT2'.

COMPARATIVE TESTS Evaluation of total elongation and breaking energy indicator of cables

The stress-strain curves of the cables were plotted by applying the ASTM D2969-04 standard of 2014 and the total elongation and the breaking energy indicator were determined for the different cables 50, 50', 60, 60', 51, 52, 53, 53', 54 according to the invention and for the state-of-the-art cables EDT1, EDT1', EDT2 and EDT2'.

In Table 3, the word “NA” means that the quantity was not measured. [Table 1] Cables 50 50' 60 60' N/ cable direction 3/S 3/S 4/Z 4/Z direction strand 54 S S S S M' 8 8 8 8 M 5 5 5 5 Rf(mm) 4.2 4.2 4.2 4.2 P (mm) 10.4 10.4 10.4 10.4 α (°) 25.8 25.8 25.8 25.8 Df(mm) 0.46 0.46 0.46 0.46 Dvt(mm) 1.12 1.12 1.12 1.12 Rf/Df 9 9 9 9 Dvt/Df 2.46 2.46 2.46 2.46 Rt(mm) 138 138 113 113 Pe (mm) 80 80 80 80 αe (°) 5.3 5.3 6.5 6.5 Dt(mm) 2.03 2.03 2.03 2.03 Dv(mm) 0.32 0.32 0.86 0.86 Rt/Dt 68 68 56 56 Dv/Dt 0.16 0.16 0.42 0.42 E1 (GPa) 4.0 - 3.8 - ML (g/m) 21.3 21.3 28.5 28.5 E2 (GPa) 73 39 59 33 At % 13.4 - 13.8 - At' % - 10.0 - 10.1 Er (MJ/m ³ ) 89 - 88 - Er' (MJ/m ³ ) - 82 - 83 As % 9.3 - 9.4 - D (mm) 4.38 4.38 4.92 4.92 Cables 51 52 53 53' 54 N/cable direction 3/Z 3/Z 3/Z 3/Z 3/Z direction strand 54 S S S S S M' 8 8 8 8 7 M 6 7 8 8 5 Rf(mm) 4.2 4.2 4.2 4.2 4.8 P (mm) 10.4 10.4 10.4 10.4 10.4 α (°) 25.8 25.8 25.8 25.8 21.8 Df(mm) 0.46 0.46 0.46 0.46 0.46 Dvt(mm) 1.12 1.12 1.12 1.12 0.84 Rf/Df 9 9 9 9 10 Dvt/Df 2.46 2.46 2.46 2.46 1.85 Rt(mm) 138 138 138 138 159 Pe (mm) 80 80 80 80 80 αe (°) 5.3 5.3 5.3 5.3 4.6 Dt(mm) 2.03 2.03 2.03 2.03 1.75 Dv(mm) 0.32 0.32 0.32 0.32 0.28 Rt/Dt 68 68 68 68 91 Dv/Dt 0.16 0.16 0.16 0.16 0.16 E1 (GPa) 3.9 4.3 8.0 - 7.1 ML (g/m) 25.5 29.4 33.4 33.4 20.4 E2 (GPa) 85 94 106 53 95 At % 11.9 8.9 8.5 - 9.0 At' % - - - 5.9 - Er (MJ/m ³ ) 82 63 56 - 72 Er' (MJ/m ³ ) - - - 48 - As % 7.8 6.0 4.6 - 5.6 D (mm) 4.38 4.38 4.38 4.38 3.78 Cables EDT1 EDT1' EDT2 EDT2' N/cable direction 4/S 4/S 4/S 4/S strands direction S S S S M' - - - - M 3 3 4 4 V 8 8 9 9 Rf(mm) N / A N / A N / A N / A P1 (mm) 6.7 6.7 5.1 5.1 P2 (mm) 10 10 7.5 7.5 α (°) N / A N / A N / A N / A Df(mm) 0.35 0.35 0.26 0.26 Dvt(mm) N / A N / A N / A N / A Rf/Df N / A N / A N / A N / A Dvt/Df N / A N / A N / A N / A Rt(mm) 9 9 6.3 6.3 Pe (mm) 20 20 15 15 αe (°) 22.5 22.5 24.8 24.8 Dt(mm) 1.48 1.48 1.15 1.15 Dv(mm) 0.84 0.84 0.80 0.80 Rt/Dt 6.1 6.1 5.4 5.4 Dv/Dt 0.57 0.57 0.70 0.70 E1 (GPa) 1.0 - 1.0 - ML (g/m) 35.8 35.8 23.1 23.1 E2 (GPa) 104 81 81 68 At % 6.0 - 8.1 - At' % - 3.4 - 4.7 Er (MJ/m3) 44 - 52 - Er' (MJ/m3) - 30 - 31 As % 2.8 - 4.3 - D (mm) 3.80 3.80 3.10 3.10

Tables 1, 2 and 3 show that the cables 50, 50', 60, 60', 51, 52, 53, 53', 54 according to the invention have both an improved breaking energy indicator and have better deformability compared to the state-of-the-art cables EDT1, EDT1', EDT2 and EDT2'.

Thus, the cables according to the invention make it possible to solve the problems mentioned in the preamble.

The invention is not limited to the embodiments previously described.

Claims (15)

1. Multi-strand cord (50) having a 1xN structure comprising a single layer (52) of N strands (54) wound in a helix about a main axis (A), each strand (54) having one layer (56) of metal filaments (F1) and comprising M>1 metal filaments wound in a helix about an axis (B), in which :

   - the cord (50) has a total elongation At > 8.10% determined by the standard ASTM D2969-04 of 2014; and characterized in that

   - the energy-at-break indicator Er of the cord (50), defined by $\mathit{Er}={\displaystyle {\int }_0^{\mathit{At}}\sigma \left(\mathit{Ai}\right)\times \mathit{dAi}}$

   

   where σ(Ai) is the tensile stress in MPa measured at the elongation Ai and dAi is the elongation such that Er is strictly greater than 52 MJ/m³.
2. Cord (50) according to the preceding claim, wherein the total elongation At ≥ 8.30% and preferably At ≥ 8.50%.
3. Cord (50) according to either one of the preceding claims, wherein the energy-at-break indicator Er of the cord (50) is greater than or equal to 55 MJ/m³.
4. Cord (50) according to any one of the preceding claims, having a structural elongation As determined by the standard ASTM D2969-04 of 2014 such that As > 4.30%, preferably As ≥ 4.50% and more preferentially As ≥ 4.60%.
5. Cord (50) according to any one of the preceding claims, having a secant modulus E1 ranging from 3.0 to 10.0 GPa, and preferably ranging from 3.5 to 8.5 GPa.
6. Cord (50) according to any one of the preceding claims, having a tangent modulus E2 ranging from 50 to 180 GPa, and preferably from 55 to 150 GPa.
7. Cord (50') extracted from a polymer matrix, the extracted cord (50') having a 1xN structure comprising a single layer (52) of N strands (54) wound in a helix about a main axis (A), each strand (54) having one layer (56) of metal filaments (F1) and comprising M>1 metal filaments wound in a helix about an axis (B), in which :

   - the extracted cord (50') has a total elongation At' ≥ 5.00% determined by the standard ASTM D2969-04 of 2014, and characterized in that :

   - the energy-at-break indicator Er' of the extracted cord (50'), defined by Er' = ${\displaystyle {\int }_0^{\mathit{At}\prime }\sigma \left(\mathit{Ai}\right)\times \mathit{dAi}}$

   

   where σ(Ai) is the tensile stress in MPa measured at the elongation Ai and dAi is the elongation such that Er' is strictly greater than 35 MJ/m³.
8. Extracted cord (50') according to the preceding claim, wherein the total elongation At' is such that At' ≥ 5.20%.
9. Extracted cord (50') according to Claim 7 or 8, wherein the energy-at-break indicator Er' of the cord (50) is greater than or equal to 40 MJ/m³.
10. Cord (50) according to any one of claims 1 to 6 or extracted cord (50') to any one of claims 7 to 9, wherein the strands (54) define an internal enclosure (59) of the cord (50) or the extract cord (50') of diameter Dv, each strand (54) having a diameter Dt and a helix radius of curvature Rt defined by Rt=Pe/(π x Sin(2αe)) where Pe is the pitch of each strand expressed in millimetres and αe is the helix angle of each strand (54), Dv, Dt and Rt being expressed in millimetres, the cord (50) or the extract cord (50') satisfying the following relationships: 25 ≤ Rt / Dt ≤ 180 and 0.10 ≤ Dv / Dt ≤ 0.50.
11. Cord (50) according to any one of claims 1 to 6 or extracted cord (50') to any one of claims 7 to 9, wherein the metal filamentary elements (F1) define an internal enclosure (58) of the strand (52) of diameter Dvt, each metal filamentary element (F1) having a diameter Df and having a helix radius of curvature Rf defined by Rf=P/(π x Sin(2α)) where P is the pitch of each metal filamentary element expressed in millimetres and α is the helix angle of each metal filamentary element (F1), Dvt, Df and Rf being expressed in millimetres, the cord (50) or the extracted cord (50') satisfying the following relationships:
    9 ≤ Rf / Df ≤ 30, and 1.30 ≤ Dvt / Df ≤ 4.50.
12. Method for manufacturing a cord (50) according to any one of Claims 1 to 6 and 10 and 11, characterized in that it comprises:

    - a step (200) of manufacturing N strands (54) via:

    - a step (100) of supplying a transitory assembly (22) comprising a layer made up of M'>1 metal filaments (F1) wound in a helix around a transitory core (16);

    - a step (110) of separating the transitory assembly (22) into:

    - a first split assembly (25) comprising a layer (26) made up of M 1 ';::: 1 metal filament(s) (F1) wound in a helix, the M1' metal filament(s) (F1) originating from the layer made up of M'>1 metal filaments (F1) of the transitory assembly (22),

    - a second split assembly (27) comprising a layer (28) made up of M2'>1 metal filament(s) (F1) wound in a helix, the M2' metal filaments (F1) originating from the layer made up of M'>1 metal filaments (F1) of the transitory assembly (22),

    - the transitory core (16) or one or more ensembles (83) comprising the transitory core (16),

    - a step (140) of reassembling the first split assembly (25) with the second split assembly (27) to form a strand (52) having one layer of metal filaments (F1) and comprising M>1 metal filaments (F1);

    - a step (300) of assembling the N strands (54) by cabling to form the cord (50).
13. Method according to the preceding claim, wherein M ranges from 3 to 18 and preferably from 4 to 15.
14. Reinforced product (R), characterized in that it comprises a polymer matrix (Ma) and at least one extracted cord (50') according to any one of Claims 7 to 11.
15. Tyre (P), characterized in that it comprises at least one extracted cord (50') according to any one of Claims 7 to 11 or a reinforced product according to Claim 14.

Images