FR3150820A1 - Multi-strand cable with two layers of multi-strands - Google Patents

Abstract

The invention relates to a multi-strand cable (50) with two layers of multi-strands, the cable (50) comprising: - an internal layer (CI) of the cable consisting of X=1 multi-strands M1 of diameter DM1 comprising K>1 strands (T1) wound in a helix around a main axis (A), each strand (T1) having at least two layers (C1, C3) with the strands (T1) being wound in a helix around an axis (B); - an outer layer (CE) of the cable consisting of Y>1 multi-strands M2 of diameter DM2 wound around the inner layer (CI) of the cable, each multi-strand M2 comprising L>1 strands (T2) wound helically around a main axis (A’), each strand (T2) being at least two-layered (C1’; C3’) with the multi-strands (T2) being wound helically around the main axis (A). The cable (50) has a structural elongation As such that As ≥ 1.0% and with a saturation ratio π x (DM1+DM2)/(Y x DM2) greater than or equal to 1.11. Figure for abstract: Fig 4

Description

Multi-strand cable with two layers of multi-strands

The invention relates to cables and a tire comprising these cables.

The state of the art is known of cables having a (1+6)x(3+8) structure as described in document FR2969181 letter B. These cables comprise 6 strands wound in a helix around a strand at a pitch of 60 mm. Each strand comprises, on the one hand, an inner layer of 3 inner wires wound in a helix at a pitch of 7.7 mm and an outer layer of 8 outer wires wound in a helix around the inner layer at a pitch of 15.4 mm. The structural elongation of the cable is less than 0.2% and the breaking force is 19,600 N.

These cables are rigid cables, they have the advantage of relieving tension on the working plies but of very substantially increasing the circumferential rigidity of the structure, leading to increased sensitivity of the crown block to attacks at the center of the tread when they are placed at the level of the additional reinforcement.

Today, there is a need to develop new cables for applications in crown plies, in particular plies with laying angles of less than 10° such as additional reinforcement. This reinforcement aims to relieve tension in the working plies, to increase the endurance performance of the tire, especially the resistance to cleavage.

The invention aims to provide a cable with a good compromise in rigidity: flexible enough to reduce the rigidity of the crown block with a breaking force sufficient to withstand extension stresses.

For this purpose, the invention relates to a multi-strand with two layers of multi-strands, in which the cable comprises:
- an internal layer of the cable consisting of X=1 multi-strands M1 of diameter DM1 comprising K>1 strands wound in a helix around a main axis, each strand having at least two layers comprising:
- an internal layer consisting of Q1 internal metal wire(s), and
- an outer layer consisting of Q3 external metal wires wound around the inner layer, and
- an outer layer of the cable consisting of Y>1 multi-strands M2 of diameter DM2 wound around the inner layer of the cable, each multi-strand M2 comprising L>1 strands wound helically around an axis, each strand having at least two layers comprising:
- an internal layer consisting of Q1' internal metal wire(s), and
- an outer layer made of Q3' external metal wires wound around the inner layer,
with the multi-strands being wound helically around the main axis,
the cable has a structural elongation As such that As ≥ 1.0%, the structural elongation As being determined according to ASTM D2969-04 of 2014 for the cable so as to obtain a force-elongation curve, the structural elongation As being equal to the elongation, in %, corresponding to the intersection between the tangent to the elastic part of the force-elongation curve at any point on its elastic part and the axis of elongations of the force-elongation curve; and
with a saturation ratio π x (DM1+DM2)/(Y x DM2) greater than or equal to 1.11.

Thanks to this multi-strand cable configuration with two layers of desaturated multi-strands, the cable according to the invention makes it possible to obtain a cable with sufficient structural elongation providing flexibility in extension and sufficient metal mass, while keeping fine wires for flexibility in bending, to improve the compromise between shear in the polymer matrix, flexibility and resistance of the crown block and thus improve the compromise of aggression and cleavage performance.

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 intersection between the tangent to the elastic part of the force-elongation curve and the axis of the elongations 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 a structural elongation of the cable resulting from the bringing together of the different strands and metal wires 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 metal wires. The plastic part corresponds to the plastic elongation resulting from the plasticity (irreversible deformation beyond the elastic limit) of the metal wires.

In the invention, the cable comprises two layers of multi-strands, that is to say it comprises an assembly consisting of a layer of Y>1 multi-strands wound around a single layer of multi-strands, no more and no less, that is to say the assembly has two layers of multi-strands, not one, not three, but only two.

In the invention, the multi-strand is a single-strand layer, i.e. it comprises an assembly consisting of one layer of strand, no more and no less, i.e. the assembly has one layer of strand, not zero, not two, but only one.

In one embodiment, the inner multi-strand of the cable is surrounded by a polymeric composition and then the outer layer.

Advantageously, each strand has cylindrical layers.

Advantageously, each strand in the multi-strand is two-layer, that is, it comprises an assembly consisting of two layers of metal wires, no more and no less, that is, the assembly has two layers of metal wires, not one, not three, but only two. The outer layer of each strand is wound around the inner layer of that strand in contact with the inner layer of that strand.

Very advantageously, each strand of the inner layer and each strand of the outer layer are cylindrical layers. It is recalled that such cylindrical layers are obtained when the different layers of strands are wound at different pitches and/or when the winding directions of these layers are distinct from one layer to another. A strand with cylindrical layers is very highly penetrable unlike a strand with compact layers in which the pitches of all the layers are equal and the winding directions of all the layers are identical which has a much lower penetrability.

Advantageously, each strand of the inner layer and each strand of the outer layer are desaturated, that is to say that there is a space between the outer layer wires, allowing the elastomeric composition to impregnate each strand.

Preferably, the strands do not undergo pre-forming.

By definition, the diameter of the multi-strands of the inner layer DM1 or outer layer DM2 is the diameter of the smallest circle in which the multi-strand is circumscribed.

By definition, the diameter of the strands of the inner layer DT1 or outer layer DT2 is the diameter of the smallest circle in which the strand is circumscribed.

The DM1 diameter of the M1 multi-strand is calculated as follows:
We first calculate the diameter of the strand T1: DT1 = 2 x Re1 + d1 + 2 x d2 + 2*d3
with Re1 is the winding radius of the inner layer of the inner strand, with
- if the inner layer of the outer strand contains only 1 inner metal wire: Re1=0: ;
- Otherwise,

with p1 the pitch of the inner layer in the strand T1
DM1 = 2 x ReT1 + DT1
with ReT1 is the winding radius of the strand,

with P1 is the assembly pitch of the multi-strand M1.

The DM2 diameter of the M2 multi-strand is calculated in the same way:
We first calculate the diameter of the strand T2: DT2 = 2 x Re1' + d1' + 2 x d2' + 2*d3'
with Re1' is the winding radius of the inner layer of the outer strand, with
- if the inner layer of the outer strand contains only 1 inner metal wire: Re1'=0
- Otherwise,

with p1' the pitch of the inner layer in strand T2
DM2 = 2 x ReT2 + DT2
with ReT2 is the winding radius of the strand,

with P2 is the assembly pitch of the multistrand M2.

The saturation ratio is defined by the perimeter formed by the center of the multi-strands of the outer layer divided by the sum of the diameters of the multi-strands of the outer layer.

It is calculated as follows: π x (DM1+DM2) / (Y x DM2).

This saturation ratio greater than or equal to 1.11 makes it possible to desaturate the multi-strands to guarantee penetration of the polymer matrix to the internal layers of the cable to improve the corrosion and endurance performance of the tire.

The cable as defined above and according to the invention is bare, that is to say devoid of any polymeric composition, in particular the cable is devoid of any elastomeric composition.

By metal wire is meant a metal monofilament comprising a core consisting mainly (i.e. for more than 50% of its mass) or entirely (for 100% of its mass) of a metal material, for example carbon steel. The metal wire may advantageously comprise a layer of a metal coating covering the core, the metal coating being chosen from zinc, copper, tin and alloys of these metals, for example brass. Each wire is preferably made of pearlitic or ferrito-pearlitic carbon steel.

The values of the characteristics described in this application for the bare cable are measured on or determined from the cables directly after manufacture, that is to say before any step of embedding in a polymer matrix, in particular an elastomeric one.

In the present application, any interval of values designated by the expression "between a and b" represents the domain of values from more than a to less than b (i.e. excluding limits a and b) while any interval of values designated by the expression "from a to b" means the domain of values from the limit "a" to the limit "b" i.e. including the strict limits "a" and "b".

Advantageously, As ≥ 1.5% and preferably As ≥ 2.0%.

The invention also relates to a cable extracted from a polymer matrix in which the extracted cable comprises:
- an internal layer of the cable consisting of X=1 multi-strands M1 of diameter DM1 comprising K>1 strands (T1) wound in a helix around a main axis, each strand having at least two layers comprising:
- an internal layer consisting of Q1 internal metal wire(s), and
- an outer layer consisting of Q3 external metal wires wrapped around the inner layer, and
- an outer layer of the cable consisting of Y>1 multi-strands M2 of diameter DM2 wound around the inner layer of the cable, each multi-strand M2 comprising L>1 strands wound helically around an axis, each strand having at least two layers comprising:
- an internal layer consisting of Q1' internal metal wire(s), and
- an outer layer made of Q3' external metal wires wound around the inner layer,
with the multi-strands being wound helically around the main axis,
the cable has a structural elongation As' such that As' ≥ 0.3%, the structural elongation As' being determined according to ASTM D2969-04 of 2014 for the cable so as to obtain a force-elongation curve, the structural elongation As' being equal to the elongation, in %, corresponding to the intersection between the tangent to the elastic part of the force-elongation curve at any point on its elastic part and the axis of elongations of the force-elongation curve;
with a saturation ratio π x (DM1+DM2)/(Y x DM2) greater than or equal to 1.11.

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, it 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.

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

Preferably, the cable has a cable diameter such that the diameter D of the cable ranges from 3 mm to 9.5 mm, preferably from 4 mm to 7.5 mm. The diameter D is measured on the cable according to ASTM D2969-04.

By definition, the diameter of a strand is the diameter of the smallest circle in which the strand is circumscribed.

By definition, the cable diameter is the diameter of the smallest circle in which the cable is circumscribed without the hoop.

Preferably, the diameters of the metal wires range, independently of each other, from 0.15 mm to 0.50 mm, preferably from 0.18 mm to 0.35 mm and more preferably from 0.20 mm to 0.30 mm.

Preferably, the wires of the same layer of a predetermined strand all have substantially the same diameter. Advantageously, the outer strands all have substantially the same diameter. By “substantially the same diameter” is meant that the wires or strands have the same diameter to within industrial tolerances.

Advantageously, Y is equal to 6, 7, 8, 9 or 10, preferably Y=6, 7 or 8 and more preferably Y=6.

Advantageously, K = 2, 3 or 4, preferably K = 3 or 4.

Advantageously, L = 2, 3 or 4 and preferably L = 3 or 4.

In a first embodiment, each strand of the inner layer is two-layered.

Advantageously, each strand of the outer layer is two-layered.

Advantageously, in this first embodiment, in a preferred variant, each strand of the internal and external layers has two layers.

In a second embodiment, each strand of the inner layer is three-layered and comprises:
an intermediate layer consisting of Q2 intermediate metal wires wound around the inner layer, and
an outer layer consisting of Q3 external metal wires wrapped around the middle layer.

Advantageously, each strand of the outer layer is three-layered and comprises:
an intermediate layer consisting of Q2' intermediate metal wires wound around the inner layer, and
an outer layer consisting of Q3' external metal wires wrapped around the middle layer.

Advantageously, in this second embodiment, in a preferred variant, each strand of the internal and external layers has three layers.

Advantageously, each strand is of the type not gummed in situ. By not gummed in situ, it is meant that before assembling the strands together, each strand is made up of wires from the different layers and is free of polymeric composition, in particular elastomeric composition.

Strands of m ulti-strands internal s M1 of the cable according to the invention

Advantageously, Q1=1, 2, 3 or 4, preferably Q1=1, 2 or 3 and more preferably Q1=1 or 3.

Advantageously, Q3=5, 6, 7,8, 9 or 10, preferably Q3=6, 7, 8 or 9 and more preferably Q3=6 or 8.

In one embodiment, Q1=1.

Advantageously, Q3 = 5, 6 or 7 and preferably Q3 = 6.

In another preferred embodiment, Q1>1, preferably Q1=2, 3 or 4.

Advantageously, Q3 = 7, 8, 9 or 10 and preferably Q3 = 7, 8 or 9.

In a first variant, Q1=2 and Q3=7 or 8, preferably Q1=2, Q3=7.

In a second variant, Q1=3 and Q3=7, 8 or 9, preferably Q1=3, Q3=8.

In a third variant, Q1=4 and Q3=7, 8, 9 or 10, preferably Q1=4, Q3=9.

Strands of multi-strands external M2 of the cable according to the invention

Advantageously, Q1’=1, 2, 3 or 4, preferably Q1’=1, 2 or 3 and more preferably Q1’=1 or 3.

Advantageously, Q3’=5, 6, 7, 8, 9 or 10, preferably Q3’=6, 7, 8 or 9 and more preferably Q3’ = 6 or 8.

In one embodiment, Q1’=1.

Advantageously, Q3’ =5, 6 or 7 and preferably Q3’=6.

In another preferred embodiment, Q1’>1, preferably Q1’=2, 3 or 4.

Advantageously, Q3’ =7, 8, 9 or 10 and preferably Q3’=7, 8 or 9.

In a first variant, Q1’=2 and Q3’=7 or 8, preferably Q1’=2, Q3’=7.

In a second variant, Q1’=3 and Q3’=7, 8 or 9, preferably Q1’=3, Q3’=8.

In a third variant, Q1’=4 and Q3’=7, 8, 9 or 10, preferably Q1’=4, Q3’=9.

Advantageously, Q1=1 and Q3=6, Q1’= 1 and Q3’=6.

REINFORCED PRODUCT ACCORDING TO THE INVENTION

Another object of the invention is a reinforced product comprising a polymer matrix and at least one cable or 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

Another object of the invention is a tire comprising at least one extracted cable or a reinforced product as defined above.

By tire comprising an extracted cable, we mean a tire comprising a cable whose properties, measured after extraction of the tire, are those of the extracted cable, this cable being, prior to its incorporation into the tire, a cable such as the cable described 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, a working reinforcement and an additional reinforcement, the additional reinforcement comprising at least one cable as defined above, the additional reinforcement making an angle at most equal to 10°, preferably ranging from 5° to 10° with the circumferential direction Z of the tire and being radially interposed between the working reinforcement and the carcass 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 40 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.

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 is a sectional view perpendicular to the circumferential direction of a tire according to the invention;
- there is a detailed view of zone II of the ;
- there is a sectional view of a reinforced product according to the invention;
- there 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; and
- there is a schematic sectional view perpendicular to the axis of the cable (assumed to be straight and at rest) of an extracted cable (50') according to a first embodiment of the invention.

EXAMPLE OF A TIRE ACCORDING TO THE INVENTION

In figures 1 and 2, an X, Y, Z reference point is shown corresponding to the usual axial (X), radial (Y) and circumferential (Z) orientations 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.

Figures 1 and 2 show a tire according to the invention and designated by the general reference 10.

The 10 tire is for heavy civil engineering type vehicles, for example of the “dumper” type. Thus, the 10 tire has a dimension of type 53/80R63.

The tire 10 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 10 also comprises a sealing ply 32 made of an elastomer (commonly called inner rubber) which defines the radially internal face 34 of the tire 10 and which is intended to protect the carcass ply 30 from the diffusion of air coming from the space inside the tire 10.

The crown reinforcement 14 comprises, radially from the outside to the inside of the tire 10, 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 35° with the circumferential direction Z of the tire.

The working frame 38 comprises first and second working plies 46, 48, the first ply 46 being arranged radially inside the second ply 48.

The additional reinforcement 40, also called a limiter block, one function of which is to partially absorb the mechanical inflation stresses, comprises at least one cable 50 and the additional reinforcement makes an angle of at most 10°, preferably ranging from 5° to 10° with the circumferential direction Z of the tire 10.

EXAMPLE OF A REINFORCED PRODUCT ACCORDING TO THE INVENTION

It was represented on the a reinforced product according to the invention and designated by the general reference 100. The reinforced product 100 comprises at least one cable 50, in this case several cables 50, embedded in the polymer matrix 102.

On the , the polymer matrix 102 and the cables 50 are represented in a reference frame X, Y, Z in which the Y direction is the radial direction and the X and Z directions are the axial and circumferential directions. On the , the reinforced product 100 comprises several cables 50 arranged side by side in the main direction X and extending parallel to each other within the reinforced product 100 and collectively embedded in the polymer matrix 102.

Here, the polymer matrix 102 is an elastomeric matrix based on an elastomeric composition.

CABLE ACCORDING TO A FIRST EMBODIMENT OF THE INVENTION

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

In reference to the , each reinforcing element of the additional reinforcement 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 working ply.

The 50 cable and the 50’ extracted cable are metallic and of the multi-strand type of multi-strands with two cylindrical layers. Thus, it is understood that the layers of multi-strands constituting the 50 or 50’ cable are two in number, no more, no less.

At least 50% of the metal wires, preferably at least 60%, more preferably at least 70% of the metal wires, and very preferably each metal wire of the cable comprises a steel core having a composition in accordance with standard NF EN 10020 of September 2000 and a carbon content C > 0.80% and preferably C ≥ 0.82% and at least 50% of the metal wires, preferably at least 60%, more preferably at least 70% of the metal wires, and very preferably each metal wire of the cable comprises a steel core having a composition in accordance with standard NF EN 10020 of September 2000 and a carbon content C ≤ 1.20% and preferably C ≤ 1.10%. Here, each metal wire comprises a steel core with a composition conforming to standard NF EN 10020 of September 2000 and a carbon content C = 0.86%.

Each wire has a breaking strength, denoted Rm, such that 2500 ≤ Rm ≤ 3100 MPa. The steel of these wires is said to be of SHT (“Super High Tensile”) grade. Other wires may be used, for example wires of lower grades, for example NT (“Normal Tensile”) or HT (“High Tensile”) grades, as well as wires of higher grades, for example UT (“Ultra Tensile”) or MT (“Mega Tensile”) grades.

METHOD FOR MANUFACTURING THE CABLE ACCORDING TO THE INVENTION

We will now describe an example of a manufacturing process for the multi-strand cable of multi-strand 50.

Each internal strand T1 previously described is manufactured according to known processes comprising the following steps, preferably carried out in line and continuously:

- first of all, a first assembly step by cabling or twisting the N= 6 external wires F3 around the internal wire F1 of the internal layer C1 at pitch p3 and in direction S to form the external layer C3 at a first assembly point;

- preferably a final torsion balancing step.

Each external strand T2 previously described is manufactured according to known processes comprising the following steps, preferably carried out in line and continuously:
- first of all, a first assembly step by cabling or twisting the N'= 6 external wires F3' around the internal wire F1' of the internal layer C1' at pitch p3' and in the direction S to form the external layer C3' at a first assembly point;
- preferably a final torsion balancing step.

By “torsion balancing” is meant here, in a manner well known to those skilled in the art, the cancellation of residual torsional torques (or elastic torsional return) exerted on each wire of the strand, in the outer layer.

After this final twist balancing step, the strand manufacturing is complete. Each strand is wound onto one or more receiving reels for storage, before the subsequent assembly operation by twisting the elementary strands to obtain the multi-strand cable.

For the manufacture of the multi-strands of the invention, the procedure is well known to those skilled in the art, by twisting the strands previously obtained, using twisting machines sized to assemble strands.

In a manufacturing step of the multi-strand M1 of the internal layer CI, the K=3 internal strands T1 are assembled by twisting at pitch P1 and in direction S to form the multi-strand M1 of the internal layer CI at a first assembly point.

In a manufacturing step of the multi-strands M2 of the outer layer CE, the L=3 outer strands T2 are assembled by twisting at pitch P2 and in direction S to form the multi-strands M2 of the outer layer CE at a first assembly point.

Then, in a subsequent manufacturing step, the Y=6 external multi-strands M2 are assembled by wiring around the internal layer CI at pitch pe and in the Z direction to form the assembly of the layers CI and CE. Optionally, in a final assembly step, the hoop F is wound at pitch pf in the S direction around the assembly previously obtained.

The cable 50 is then incorporated by calendering into composite fabrics formed from a known composition based on natural rubber and carbon black as a reinforcing filler, conventionally used for the manufacture of crown reinforcements of radial tires. This composition essentially comprises, in addition to the elastomer and the reinforcing filler (carbon black), an antioxidant, stearic acid, an extender oil, cobalt naphthenate as an adhesion promoter, and finally a vulcanization system (sulfur, accelerator, ZnO).

The composite fabrics reinforced by these cables comprise an elastomeric composition matrix formed by two thin layers of elastomeric composition which are superimposed on either side of the cables and which have a thickness of 1 and 4 mm respectively. The calendering pitch (cable laying pitch in the elastomeric composition fabric) ranges from 4 mm to 8 mm.

These composite fabrics are then used as a working ply in the crown reinforcement during the tire manufacturing process, the steps of which are also known to those skilled in the art.

CABLE 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 Y=5 d1= 0.26 and d3=0.23, d1’=0.30 and d3’=0.26.

Table 1 below summarizes the characteristics for the different 50, 50’ and 60 cables.

To determine the breaking force of a cable, one cable is extracted, then the multi-strands M1 and M2 are extracted and each of the multi-strands is pulled independently. The breaking force of all the multi-strands is added together and multiplied by a corrective coefficient of 95% to take into account the loss of efficiency during assembly.

Cables 50 50’ 60 M1 X=1 K 3 3 3

T1

Q1/ Q2/ Q3 1/-/6 1/-/6 1/-/6 d1/d2/d3 0.30/-/0.26 0.30/-/0.26 0.26/-/0.23 direction C1/p1 pitch (mm) S/inf S/inf S/inf direction C2/p2 pitch (mm) - - - direction C3/p3 pitch (mm) S/13.7 S/13.7 S/13.7 Direction T1 / P1 (mm) S/7.5 S/7.5 S/7.5 Y 6 6 5 M2
T2 L 3 3 3 Q1’/Q2’/Q3’ 1/-/6 1/-/6 1/-/6 d1’/d2’/ d3’ 0.26/-/0.23 0.26/-/0.23 0.30/-/0.26 direction C1’/step p1’ (mm) S/inf S/inf S/inf direction C2’/step p2’ (mm - - - direction C3’/step p3’ (mm) S/13.7 S/13.7 S/13.7 Direction T2 / P2 (mm) S/7.5 S/7.5 S/7.5 Cable/pi/pe direction Z/inf/70 Z/inf/70 Z/inf /70 DM1 (mm) 1.84 1.84 1.63 DM2 (mm) 1.63 1.63 1.84 Saturation report 1.12 1.12 1.18 As (%) 2 - 2 As’(%) - 0.5 - At (%) 3.6 - 4 D (mm) 5.1 5.1 5.3 Breaking force (N) 14907 14161 13923

And we have summarized in table 2 below the characteristics for the state-of-the-art cable described in document FR2969181 letter B.

Cable EDT (1+6)/cable direction (1+6)/S strands direction S Q1 3 Q3 8 p1 (mm) 7.7 p2 (mm) 15.4 Pi (mm) inf Pe (mm) 60 At % 2 As % 0.1 D (mm) 4.6 DM1 (mm) 1.44 DM2(mm) 1.44 Saturation report 1.05 Breaking force (N) 19600

It is noted that the cables 50, 50' and 60 according to the invention make it possible to obtain a cable with a sufficient breaking force compared to the cable of the state of the art in order to obtain a cable with a good compromise in rigidity: flexible enough to reduce the rigidity of the crown block with a sufficient breaking force to withstand the stresses in extension while having a saturation ratio greater than or equal to 1.11 which makes it possible to desaturate the multi-strands to guarantee penetration of the polymer matrix to the internal layers of the cable to improve the corrosion and endurance performance.

The invention is not limited to the embodiments previously described.

Claims (15)

Multi-strand cable (50) with two layers of multi-strands, characterized in that the cable (50) comprises:
- an internal layer (CI) of the cable consisting of X=1 multi-strands M1 of diameter DM1 comprising K>1 strands (T1) wound in a helix around a main axis (A), each strand (T1) having at least two layers (C1, C3) comprising:
- an internal layer (C1) consisting of Q1 internal metal wire(s) (F1), and
- an outer layer (C3) made up of Q3 external metal wires (F3) wound around the inner layer (C1), and
- an outer layer (CE) of the cable consisting of Y>1 multi-strands M2 of diameter DM2 wound around the inner layer (CI) of the cable, each multi-strand M2 comprising L>1 strands (T2) wound helically around an axis (A'), each strand (T2) having at least two layers (C1';C3') comprising:
- an internal layer (C1') consisting of Q1' internal metal wire(s) (F1'), and
- an outer layer (C3') made up of Q3' external metal wires (F3') wound around the inner layer (C1'),
with the multi-strands (M2) being wound helically around the main axis (A),
the cable (50) has a structural elongation As such that As ≥ 1.0%, the structural elongation As being determined according to ASTM D2969-04 of 2014 to the cable (50) so as to obtain a force-elongation curve, the structural elongation As being equal to the elongation, in %, corresponding to the intersection between the tangent to the elastic part of the force-elongation curve at any point of its elastic part and the axis of the elongations of the force-elongation curve; and
with a saturation ratio π x (DM1+DM2)/(Y x DM2) greater than or equal to 1.11. Cable (50) according to the preceding claim, in which As ≥ 1.5% and preferably As ≥ 2.0%. Multi-strand cable (50') with two layers of multi-strands extracted from a polymer matrix (102), characterized in that the extracted cable (50') comprises:
- an internal layer (CI) of the cable consisting of X=1 multi-strands M1 of diameter DM1 comprising K>1 strands (T1) wound in a helix around a main axis (A), each strand (T1) having at least two layers (C1, C3) comprising:
- an internal layer (C1) consisting of Q1 internal metal wire(s) (F1), and
- an outer layer (C3) made up of Q3 external metal wires (F3) wound around the inner layer (C1), and
- an outer layer (CE) of the cable consisting of Y>1 multi-strands M2 of diameter DM2 wound around the inner layer (CI) of the cable, each multi-strand M2 comprising L>1 strands (T2) wound helically around an axis (A'), each strand (T2) having at least two layers (C1';C3') comprising:
- an internal layer (C1') consisting of Q1' internal metal wire(s) (F1'), and
- an outer layer (C3') made up of Q3' external metal wires (F3') wound around the inner layer (C1'),
with the multi-strands (M2) being wound helically around the main axis (A),
the cable (50') has a structural elongation As' such that As' ≥ 0.3%, the structural elongation As' being determined according to ASTM D2969-04 of 2014 for the cable (50') so as to obtain a force-elongation curve, the structural elongation As' being equal to the elongation, in %, corresponding to the intersection between the tangent to the elastic part of the force-elongation curve at any point on its elastic part and the axis of elongations of the force-elongation curve; and
with a saturation ratio π x (DM1+DM2)/(Y x DM2) greater than or equal to 1.11. Cable (50,50') according to any one of the preceding claims, in which the diameter D of the cable ranges from 3 mm to 9.5 mm, preferably from 4 mm to 7.5 mm. Cable (50,50') according to any one of the preceding claims, in which the diameters of the metal wires (F1; F3; F1'; F3') range independently of each other from 0.15 mm to 0.50 mm, preferably from 0.18 mm to 0.35 mm and more preferably from 0.20 mm to 0.30 mm. Cable (50,50’) according to any one of the preceding claims, in which Y is equal to 5, 6, 7, 8, 9 or 10, preferably Y=6, 7 or 8 and more preferably Y=6. Cable (50,50') according to any one of the preceding claims, in which K= 2, 3 or 4, preferably K=3 or 4. Cable (50,50’) according to any one of the preceding claims, in which L = 2,3 or 4 and preferably L =3 or 4. Cable (50,50') according to any one of the preceding claims, in which each strand (T1) of the inner layer (CI) is two-layer (C1, C3). Cable (50,50') according to any one of claims 1 to 8, in which each strand (T2) of the outer layer (CE) has two layers (C1', C3'). Cable (60) according to any one of claims 1 to 8, in which each strand (T1) of the inner layer (CI) is three-layered (C1, C2, C3) and comprises:
an intermediate layer (C2) consisting of Q2 intermediate metal wires (F2) wound around the inner layer (C1), and
an outer layer (C3) consisting of Q3 external metal wires (F3) wound around the intermediate layer (C2). Cable (60) according to any one of claims 1 to 8, in which each strand (T2) of the outer layer (CE) is three-layered (C1', C2', C3') and comprises:
an intermediate layer (C2') consisting of Q2' intermediate metal wires (F2') wound around the inner layer (C1'), and
an outer layer (C3') consisting of Q3' external metal wires (F3') wound around the intermediate layer (C2'). Cable (50,50') according to any one of claims 1 to 10, in which each strand (T1; T2) of the inner and outer layers (CI; CE) is two-layer (C1, C3, C1', C2'). Reinforced product (100), characterized in that it comprises a polymer matrix (102) and at least one extracted cable (50') such that the properties of this cable, measured after extraction, are those of the extracted cable (50') according to any one of claims 3 to 13. Tire (10), characterized in that it comprises at least one extracted cable (50') such that the properties of this cable, measured after extraction of the tire, are those of the extracted cable (50') according to any one of claims 3 to 13 or a reinforced product according to claim 14.