Multi-strand cable with two layers of multi-strands

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=3 or 4 multi-strands M1 of diameter DM1 comprising K=2, 3 or 4 strands (T1) wound in a helix around an axis (B), each strand (T1) having at least two layers (C1, C3); - 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=2, 3 or 4 strands (T2) wound helically around an axis (A'), each strand (T2) being at least two-layered (C1'; C3') with the multi-strands of the inner layer (M1) and the outer layer (M2) being wound helically around a main axis (A). The cable (50) has a structural elongation As such that As ≥ 1.0% and with a saturation ratio π x (2 x ReM1 + DM1+DM2) / ( Y x DM2) greater than or equal to 1.11. Figure for abstract: Fig 4

Description

Title of the invention: Multi-strand cable with two layers of multi-strands

[0001] The invention relates to cables and a tire comprising these cables.

[0002] Known from the state of the art are cables having a (1+6)x(3+8) structure as described in document FR2969181 letter B. These cables comprise 6 strands wound helically around a strand at a pitch of 60 mm. Each strand comprises, on the one hand, an inner layer of 3 inner wires wound helically at a pitch of 7.7 mm and an outer layer of 8 outer wires wound helically around the inner layer at a pitch of 15.4 mm. The structural elongation of the cable is less than 2% and the breaking force is 19,600 N.

[0003] 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.

[0004] Today, a need is emerging for the development of new cables for crown ply applications, in particular plies with laying angles of less than 10° such as the 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.

[0005] The invention aims to provide a cable having a good compromise in rigidity: flexible enough to reduce the rigidity of the crown block with a breaking force sufficient to withstand extension stresses.

[0006] For this purpose, the invention relates to a multi-strand cable with two layers of multi-strands, in which the cable comprises: - an internal layer of the cable consisting of X=3 or 4 multi-strands Ml of diameter DM1 comprising K=2, 3 or 4 strands wound in a helix around an axis at pitch pi, each strand being at least two layers comprising: - an inner layer consisting of Q internal metal wire(s) of diameter dl, and - an outer layer consisting of Q3 external metal wires of diameter d3 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=2, 3 or 4 strands wound helically around an axis, each strand being at least two-layered comprising: - an internal layer consisting of Ql' internal metal wire(s) of diameter dl', And - an outer layer consisting of Q3' external metal wires of diameter d3' wound around the inner layer, with the multi-strands of the inner layer and the outer layer being wound helically around a 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 ir x (2 x ReMl + DMl+DM2) / ( Y x DM2) greater than or equal to 1.11 with ReMl being the winding radius of the inner layer of the multi-strand Ml determined by

[0007] 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 the shears in the polymer matrix, the flexibility and the resistance of the crown block and thus improve the compromise of aggression and cleavage performance.

[0008] 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 metal wires. The plastic part corresponds to the plastic elongation resulting from the plasticity (irreversible deformation beyond the elastic limit) of the metal wires.

[0009] 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.

[0010] 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.

[0011] In one embodiment, the internal multi-strands of the cable are surrounded by a polymeric composition and then by the external layer.

[0012] Advantageously, each strand has cylindrical layers.

[0013] 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.

[0014] 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 much lower penetrability.

[0015] 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.

[0016] Preferably, the strands do not undergo pre-forming.

[0017] 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.

[0018] By definition, the diameter of the strands of the inner layer DTI or outer layer DT2 is the diameter of the smallest circle in which the strand is circumscribed.

[0019] The diameter DM1 of the multi-strand Ml is calculated as follows: First we calculate the diameter of the strand Tl: DTI = 2 x Rel + dl + 2 x d2 + 2 x d3 with Rel 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: Rel=0: ; - Otherwise, with pl the pitch of the inner layer in the strand Tl DM1 = 2xReTl + DT1 with ReTl is the winding radius of the strand, with Pl is the assembly pitch of the multi-strand Ml.

[0020] The diameter DM2 of the multi-strand M2 is calculated in the same way: We first calculate the diameter of the strand T2: DT2 = 2 x Rel' + dl' + 2 x d2' + 2 x d3' with Rel' 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: Rel'=0 - Otherwise, with pl' the pitch of the inner layer in the strand T2 DM2 = 2 x ReT2 + DT2 with ReT2 is the winding radius of the strand, with P2 is the assembly pitch of the multi-strand M2.

[0021] 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.

[0022] It is calculated as follows: ir x (2 x ReMl + DM1+DM2) / ( Y x DM2) with ReMl being the winding radius of the inner layer of the multi-strand Ml determined by

[0023] 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.

[0024] Advantageously, the cable as defined above is bare, that is to say devoid of any polymeric composition, in particular the cable is devoid of any elastomeric composition.

[0025] 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 metallic material, for example carbon steel. The metal wire may advantageously comprise a layer of a metallic coating covering the core, the metallic 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.

[0026] The values ​​of the characteristics described in the present 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 polymeric matrix, in particular an elastomeric one.

[0027] In the present application, any interval of values ​​designated by the expression "between a and b" represents the range of values ​​going from more than a to less than b (i.e. bounds a and b excluded) while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​going from the bound "a" to the bound "b" i.e. including the strict bounds "a" and "b".

[0028] Advantageously, As > 1.5% and preferably As > 2.0%.

[0029] 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=3 or 4 multi-strands Ml of diameter DM1 comprising K=2, 3 or 4 strands wound in a helix around a main axis at pitch pi, each strand being at least two layers comprising: - an inner layer consisting of Q internal metal wire(s) of diameter dl, and - an outer layer consisting of Q3 external metal wires of diameter d3 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=2, 3 or 4 strands wound helically around an axis, each strand being at least two-layered comprising: - an internal layer consisting of Ql' internal metal wire(s) of diameter dl', and - an outer layer made up of Q3' external metal wires of diameter d3' wound around the inner layer, with the multi-strands of the inner layer and outer layer being wound helically around a 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; and with a saturation ratio ir x (2 x ReMl + DMl+DM2) / ( Y x DM2) greater than or equal to 1.11 with ReMl being the winding radius of the inner layer of the multi-strand Ml determined by

[0030] Preferably, the polymeric matrix is ​​an elastomeric matrix.

[0031] The polymeric matrix, preferably elastomeric, is based on a polymeric composition, preferably elastomeric.

[0032] By polymeric matrix is ​​meant a matrix comprising at least one polymer. The polymeric matrix is ​​thus based on a polymeric composition.

[0033] By elastomeric matrix is ​​meant a matrix comprising at least one elastomer. The preferred elastomeric matrix is ​​thus based on the elastomeric composition.

[0034] 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 the totally or partially crosslinked state or in the non-crosslinked state.

[0035] 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.

[0036] 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 which can be used for these plies are conventional compositions for calendering reinforcing filamentary 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.

[0037] The values ​​of the characteristics described in the present application for the extracted cable are measured on or determined from cables extracted from a polymeric matrix, in particular an elastomeric one, 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 polymeric 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 the polymer matrix locally attached to the cable and taking care not to damage the surface of the metal wires.

[0038] The advantageous characteristics described below apply equally to the cable as defined above and to the extracted cable.

[0039] Preferably, the cable has a cable diameter such that the diameter D of the cable ranges from 4 mm to 10 mm, preferably from 5 mm to 8 mm.

[0040] By definition, the diameter of a strand is the diameter of the smallest circle in which the strand is circumscribed.

[0041] 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.

[0042] 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.

[0043] Advantageously, Y is equal to 5, 6, 7, 8, 9 or 10, preferably Y=8 or 9.

[0044] Advantageously, K= 2, 3 or 4, preferably K=3 or 4.

[0045] Advantageously, L = 2, 3 or 4 and preferably L = 3 or 4.

[0046] In a first embodiment, each strand of the inner layer is two-layered.

[0047] Advantageously, each strand of the outer layer has two layers.

[0048] Advantageously, in this first embodiment, in a preferred variant, each strand of the internal and external layers has two layers.

[0049] 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.

[0050] 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 intermediate layer.

[0051] Advantageously, in this second embodiment, in a preferred variant, each strand of the internal and external layers has three layers.

[0052] 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 the wires of the different layers and is free of polymeric composition, in particular elastomeric composition.

[0053] Strands of the internal multi-strands Ml of the cable according to the invention

[0054] Advantageously, Ql=1, 2, 3 or 4, preferably Q1=1, 2 or 3 and more preferably Ql=1 or 3.

[0055] Advantageously, Q3=5, 6, 7, 8, 9 or 10, preferably Q3=6, 7, 8 or 9 and more preferably Q3 = 6 or 8.

[0056] In one embodiment, Ql=l.

[0057] Advantageously, Q3 = 5, 6 or 7 and preferably Q3 = 6.

[0058] In another preferred embodiment, Ql> 1, preferably Ql=2, 3 or 4.

[0059] Advantageously, Q3 = 7, 8, 9 or 10 and preferably Q3 = 7, 8 or 9.

[0060] In a first variant, Q 1=2 and Q3=7 or 8, preferably Ql=2, Q3=7.

[0061] In a second variant, Ql=3 and Q3=7, 8 or 9, preferably Ql=3, Q3=8.

[0062] In a third variant, Ql=4 and Q3=7, 8, 9 or 10, preferably Ql=4, Q3=9.

[0063] Strands of the external multi-strands M2 of the cable according to the invention

[0064] Advantageously, Ql'=1, 2, 3 or 4, preferably Ql'=1, 2 or 3 and more preferably Ql'= 1 or 3.

[0065] Advantageously, Q3'=5, 6, 7, 8, 9 or 10, preferably Q3'= 6, 7, 8 or 9 and more preferably Q3' = 6 or 8.

[0066] In one embodiment, Ql'=l.

[0067] Advantageously, Q3' = 5, 6 or 7 and preferably Q3'=6.

[0068] In another preferred embodiment, Q1 '>1, preferably Ql'=2, 3 or 4.

[0069] Advantageously, Q3' =7, 8, 9 or 10 and preferably Q3'=7, 8 or 9.

[0070] In a first variant, Ql'=2 and Q3'=7 or 8, preferably Ql'=2, Q3'=7.

[0071] In a second variant, Ql'=3 and Q3'=7, 8 or 9, preferably Ql'=3, Q3'=8.

[0072] In a third variant, Ql'=4 and Q3'=7, 8, 9 or 10, preferably Ql'=4, Q3'=9.

[0073] Advantageously, Ql=1 and Q3=6, Ql'= 1 and Q3'=6.

[0074] REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0075] Another object of the invention is a reinforced product comprising a polymer matrix and at least one cable or extracted cable as defined above.

[0076] 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.

[0077] PNEUMATIC ACCORDING TO THE INVENTION

[0078] Another object of the invention is a tire comprising at least one cable extract or a reinforced product as defined above.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] The cable is particularly intended for industrial vehicles chosen 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.

[0083] Preferably, the tire is for a civil engineering type vehicle. 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.

[0084] 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.

[0085] The invention will be better understood by reading the examples which follow, given solely as non-limiting examples and made with reference to the drawings in which: - [Fig.l] is a sectional view perpendicular to the circumferential direction of a tire according to the invention; - [Fig.2] is a detailed view of zone II of [Fig.l]; - [Fig.3] is a sectional view of a reinforced product according to the invention; - [Fig.4] is a schematic sectional view perpendicular to the axis of the cable (assumed to be rectilinear and at rest) of a cable (50) according to a first embodiment of the invention; and - [Fig.5] is a schematic sectional view perpendicular to the axis of the cable (assumed to be rectilinear and at rest) of an extracted cable (50') according to a first embodiment of the invention.

[0086] EXAMPLE OF A TIRE ACCORDING TO THE INVENTION

[0087] In Figures 1 and 2, a reference X, Y, Z is shown corresponding to the usual axial (X), radial (Y) and circumferential (Z) orientations of a tire.

[0088] 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.

[0089] Figures 1 and 2 show a tire according to the invention and designated by the general reference 10.

[0090] The tire 10 is for a heavy vehicle of the civil engineering type, for example of the “dumper” type. Thus, the tire 10 has a dimension of the 53 / 80R63 type.

[0091] 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.

[0092] 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).

[0093] The tire 10 also comprises a sealing ply 32 made of an elastomer (commonly called inner rubber) which defines the radially inner 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.

[0094] The crown reinforcement 14 comprises, radially from the outside towards 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 ra- dially interposed between the tread 22 and the working reinforcement 38. The working reinforcement 38 is radially interposed between the protective reinforcement 36 and the additional reinforcement 40.

[0095] The protective reinforcement 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.

[0096] The working frame 38 comprises first and second working plies 46, 48, the first ply 46 being arranged radially inside the second ply 48.

[0097] 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 at most equal to 10°, preferably ranging from 5° to 10° with the circumferential direction Z of the tire 10.

[0098] EXAMPLE OF REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0099] [Fig. 3] shows 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.

[0100] In [Fig. 3], the polymer matrix 102 is shown, the cables 50 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. In [Fig. 3], 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.

[0101] Here, the polymeric matrix 102 is an elastomeric matrix based on an elastomeric composition.

[0102] CABLE ACCORDING TO A FIRST EMBODIMENT OF THE INVENTION

[0103] [Fig.4] shows the cable 50 according to a first embodiment of the invention.

[0104] With reference to [Fig.5], 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.

[0105] The cable 50 and the extracted cable 50' are metallic and of the multi-strand type of multi- two-layer cylindrical strands. Thus, we understand that the layers of multi-strands constituting the 50 or 50' cable are two in number, no more, no less.

[0106] 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 having a composition in accordance with standard NF EN 10020 of September 2000 and a carbon content C = 0.86%.

[0107] 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 grade, for example NT (“Normal Tensile”) or HT (“High Tensile”) grade, as well as wires of higher grade, for example UT (“Ultra Tensile”) or MT (“Mega Tensile”) grade.

[0108] METHOD FOR MANUFACTURING THE CABLE ACCORDING TO THE INVENTION

[0109] We will now describe an example of a method for manufacturing the multi-strand cable 50.

[0110] Each internal strand T1 previously described is manufactured according to known processes comprising the following steps, preferably carried out in line and continuously:

[0111] - first of all, a first assembly step by wiring or twisting the 6 wires external F3 around the internal wire Fl of the internal layer Cl at step p3 and in the direction S to form the external layer C3 at a first assembly point;

[0112] - preferably a final torsion balancing step.

[0113] 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 wiring or twisting the 6 external wires F3' around the internal wire Fl' of the internal layer Cl' at step p3' and in the direction S to form the external layer C3' at a first assembly point; - preferably a final torsion balancing step.

[0114] 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.

[0115] After this final twist balancing step, the manufacture of the strand 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.

[0116] 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.

[0117] In a step of manufacturing a multi-strand Ml, the K=3 internal strands Tl are assembled by wiring at pitch PI and in direction S to form a multi-strand Ml of the internal layer CI at a first assembly point.

[0118] In a step of manufacturing the internal layer CI, the X=3 multi-strands Ml are assembled by wiring at pitch pi and in the Z direction to form the internal layer CI at a first assembly point.

[0119] In a step of manufacturing the multi-strands M2 of the outer layer CE, the L=3 outer strands T2 are assembled by cabling at pitch P2 and in direction S to form the multi-strands M2 of the outer layer CE at a first assembly point.

[0120] Then, in a subsequent manufacturing step, the Y=9 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 previously obtained assembly.

[0121] 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).

[0122] The composite fabrics reinforced by these cables comprise a matrix of elastomeric composition formed of two thin layers of elastomeric composition which are superimposed on either side of the cables and which respectively have a thickness ranging from 1 and 4 mm. The calendering pitch (no laying of the cables in the fabric of elastomeric composition) ranges from 4 mm to 8 mm.

[0123] 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.

[0124] CABLE ACCORDING TO A SECOND EMBODIMENT OF THE INVENTION

[0125] Unlike the first embodiment described previously, the cable 60 according to the second embodiment is such that Y=8 dl= 0.26 and d3=0.23, dl'=0.30 and d3'=0.26.

[0126] The characteristics for the different 50, 50' and 60 cables are summarized in Table 1 below.

[0127] 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 90% to take into account the loss of assembly efficiency.

[0128] [Tableauxl] Cables 50 50' 60 C2 / p2 pitch (mm) - - - direction C3 / p3 pitch (mm) S / 13.7 S / 13.7 S / 13.7 Direction Tl / Pl (mm) S / 7.5 S / 7.5 S / 7.5 Y 9 9 8 M 2 T2 L 3 3 3 Q17Q27Q3' 1 / 76 1 / 76 1 / 76 dl' / d27d3' 0.26 / 70.23 0.26 / 70.23 0.30 / 70.26 direction C17step pl' (mm) S / inf S / inf S / inf direction C27step p2' (mm - - - direction C37step p3' (mm) S / 13.7 S / 13.7 S / 13.7 Direction T2 / P2 (mm) S / 7.5 S / 7.5 S / 7.5 Direction of cable / pi / pe ZZ / 50 / 80 ZZ / 50 / 80 ZZ / 50 / 80 DM1 (mm) 1.84 1.84 1.63 DM2 (mm) 1.63 1.63 1.84 Saturation ratio 1.20 1.20 1.14 As (%) 2 - 2 As'(%) - 0.5 - At (%) 3.6 - 4 D (mm) 7.2 7.2 7.2 Breaking force (daN) 24546 23319 23877

[0129] And we have summarized in table 2 below the characteristics for the cable of the state of the art described in document FR2969181 letter B.

[0130] [Tables2] EDT cable (l+6) / cable direction (l+6) / S strand direction S Q1 3 Q3 8 pl (mm) 7.7 p2 (mm) 15.4 Pi (mm) inf Pe (mm) 60 At% 2 As % 0.1 DM1 (mm) 1.44 DM2(mm) 1.44 Saturation ratio 1.05 Breaking force (daN) 19600

[0131] It is noted that the cables 50, 50' and 60 according to the invention make it possible to obtain a cable with sufficient breaking strength compared to the cable of the state of the art in order to obtain a cable with a good compromise of rigidity: flexible enough to reduce the rigidity of the crown block with sufficient breaking strength 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.

[0132] The invention is not limited to the embodiments previously described.

Claims

Claims

1. A 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=3 or 4 multi-strands Ml of diameter DM1 comprising K=2, 3 or 4 strands (Tl) wound in a helix around an axis (B) at pitch pi, each strand (Tl) having at least two layers (Cl, C3) comprising: - an internal layer (Cl) made up of Ql internal metal wire(s) (Fl) of diameter dl, and - an outer layer (C3) consisting of Q3 external metal wires (F3) of diameter d3 wound around the inner layer (Cl); 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=2, 3 or 4 strands (T2) wound helically around an axis (A'), each strand (T2) being at least two-layered (Cl'; C3') comprising: - an internal layer (Cl') consisting of Ql' internal metal wire(s) (Fl') of diameter dl', and - an outer layer (C3') consisting of Q3' external metal wires (F3') of diameter d3' wound around the inner layer (Cl'), with the multi-strands of the inner layer (Ml) and of the outer layer (M2) being wound helically around a main axis (A), the cable (50) has a structural elongation As such that As > 1.0%, the structural elongation As being determined according to the ASTM D2969-04 standard 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 elongations of the force-elongation curve; and with a saturation ratio ir x (2 x ReMl + DMl+DM2) / ( Y x DM2) greater than or equal to 1.11 with ReMl being the winding radius of the inner layer of the multi-strand Ml determined by

2. Cable (50) according to the preceding claim, in which As > 1.5% and preferably As > 2.0%.

3. 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 inner layer (CI) of the cable consisting of X=3 or 4 multi-strands Ml of diameter DM1 comprising K=2, 3 or 4 strands (Tl) wound helically around a main axis (B) at pitch pi, each strand (Tl) being at least two layers (Cl, C3) comprising: - an inner layer (Cl) consisting of Ql internal metal wire(s) (Fl) of diameter dl, and - an outer layer (C3) consisting of Q3 external metal wires (F3) of diameter d3 wound around the inner layer (Cl); 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=2, 3 or 4 strands (T2) wound in a helix around an axis (A'), each strand (T2) having at least two layers (Cl';C3') comprising: - an inner layer (Cl') consisting of Ql' inner metal wire(s) (Fl') of diameter dl', and - an outer layer (C3') consisting of Q3' outer metal wires (F3') of diameter d3' wound around the inner layer (Cl'), with the multi-strands of the inner layer (Ml) and of the outer layer (M2) being wound helically around a 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 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 ir x (2 x ReMl + DMl+DM2) / ( Y x DM2) greater than or equal to 1.11 with ReMl being the winding radius of the inner layer of the multi-strand Ml determined by; z 1 / 2 ; I / DM1;2 / \ / /

4. Cable (50; 50') according to any one of the preceding claims, wherein the diameter D of the cable ranges from 4 mm to 10 mm, preferably from 5 mm to 8 mm.

5. 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.

6. Cable (50,50') according to any one of the preceding claims, wherein Y is equal to 5, 6, 7, 8, 9 or 10, preferably Y=8 or 9.

7. Cable (50,50') according to any one of the preceding claims, in which K=3 or 4.

8. Cable (50,50') according to any one of the preceding claims, wherein L = 3 or 4.

9. Cable (50; 50') according to any one of claims 1 to 8, wherein each strand (T1) of the inner layer (CI) is two-layer (Cl, C3).

10. Cable (50; 50') according to any one of claims 1 to 8, wherein each strand (T2) of the outer layer (CE) is two-layer (C1', C3').

11. A cable (60) according to any one of claims 1 to 8, wherein each strand (T1) of the inner layer (C1) 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 outer metal wires (F3) wound around the intermediate layer (C2).

12. Cable (60) according to any one of claims 1 to 8, wherein each strand (T2) of the outer layer (CE) is three-layered (CE, C2', C3') and comprises: an intermediate layer (C2') consisting of Q2' intermediate metal wires (F2') wound around the inner layer (Cl'), and an outer layer (C3') consisting of Q3' external metal wires (F3') wound around the intermediate layer (C2').

13. Cable (50; 50') according to any one of claims 1 to 10, wherein each strand (T1; T2) of the inner and outer layers (CI; CE) is two-layer (Cl, C3, Cl', C3').

14. Reinforced product (100), characterized in that it comprises a polymer matrix (Ma) and at least one 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.

15. Tire (10), characterized in that it comprises at least one cable (50') such that the properties of this cable, measured after extraction from 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.

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