Multi-strand cable with two layers, sheathed inner layer, and improved penetration.

Description

[0001] The invention relates to multi-strand cables usable in particular for the reinforcement of tires, especially tires for heavy industrial vehicles.

[0002] A radially reinforced tire comprises a tread, two inextensible beads, two sidewalls connecting the beads to the tread, and a crown belt, or crown reinforcement, arranged circumferentially between the carcass reinforcement and the tread. This crown reinforcement comprises several layers of elastomeric composition, possibly reinforced by reinforcing elements such as cables or monofilaments, of metallic or textile type.

[0003] The crown reinforcement generally comprises at least two superimposed crown layers, sometimes called working layers or crossed layers, whose reinforcing elements, generally metallic, are arranged practically parallel to each other within a layer, but crossed from one layer to the other, that is to say inclined, symmetrically or not, with respect to the median circumferential plane, at an angle that is generally between 10° and 45°. The working layers generally include reinforcing elements with very low elongation in order to ensure their function of guiding the tire.

[0004] The top reinforcement may also include various other auxiliary layers or sheets of elastomeric composition, of varying widths depending on the application, with or without reinforcing elements. Examples include protective layers designed to protect the rest of the belt from external damage and perforations, and reinforcing layers with reinforcing elements oriented approximately along the circumferential direction (so-called zero-degree layers), whether radially external or internal to the working layers. Protective layers generally include reinforcing elements with high elongation so as to deform under the stress exerted by an indenter, such as a rock.

[0005] A prior art reinforcement element for a working web comprising a two-layer, multi-strand wire rope as disclosed in examples WO2016051669 is known. This rope comprises an inner layer consisting of one inner strand and an outer layer consisting of seven outer strands wound helically around the inner layer. The inner strand comprises an inner layer of two inner wires and an outer layer of nine outer wires. Each outer strand comprises an inner layer of three inner wires and an outer layer of eight outer wires.

[0006] We also know the state of the art, the US2004045652 application.

[0007] Document WO2019122720 A1 discloses a two-layer multi-strand cable, in which the outer layers of the inner and outer strands are desaturated.

[0008] Heavy-duty industrial vehicle tires, particularly those used in construction, are subjected to numerous stresses. Indeed, these types of tires typically operate on rough surfaces, sometimes leading to tread perforations. These perforations allow corrosive agents, such as air and water, to enter, oxidizing the metallic reinforcement elements of the crown reinforcement, especially the crown plies, and significantly reducing the tire's lifespan.

[0009] One solution for increasing tire lifespan is to combat the spread of corrosive agents. This can be achieved by coating each metal wire with an elastomeric compound during cable manufacturing. In this process, the elastomeric compound penetrates the capillaries between each layer of each strand, thus preventing the spread of corrosive agents. Such cables, generally called in-situ gummed cables, are well-known in the prior art, as described in US8863490.

[0010] Another solution for increasing tire lifespan is to increase the cable's breaking strength. Generally, breaking strength is increased by increasing the diameter of the wires constituting the cable and / or the number of wires and / or the unit strength of each wire. However, further increasing the wire diameter, for example beyond 0.45 mm as in application WO2016051669, necessarily leads to a decrease in cable flexibility, which is undesirable. Increasing the number of wires usually results in a decrease in the strand penetration due to the elastomer composition. Finally, increasing the unit strength of each wire requires significant investment in wire manufacturing facilities.

[0011] The invention aims at a cable exhibiting improved penetrability of its external strands and better accessibility of the internal strand by the elastomer composition compared to the cable of application WO2016051669, thus reducing the entry and propagation of corrosive agents in and along the cable without degrading the breaking strength of the cable. CABLE ACCORDING TO THE INVENTION

[0012] For this purpose, the invention relates to a two-layer multi-strand cable according to claim 1.

[0013] Any range of values ​​designated by the expression "between a and b" represents the range of values ​​from more than a to less than b (i.e., excluding bounds a and b) while any range of values ​​designated by the expression "from a to b" means the range of values ​​from the bound "a" to the bound "b", i.e., including the strict bounds "a" and "b".

[0014] By definition, the helix radius R2 of the outer layer of the cable is the radius of the theoretical circle passing through the centers of the outer strands of the outer layer in a plane perpendicular to the axis of the cable.

[0015] By definition, the diameter of a strand is the diameter of the smallest circle in which the strand is circumscribed.

[0016] By definition, a desaturated layer of wires is one in which there is sufficient space between the metal wires to allow the passage of a non-crosslinked elastomer composition. According to the invention, the outer layer of each strand is desaturated, meaning that the metal wires of the outer layer do not touch and that there is sufficient space between two adjacent outer metal wires to allow the passage of an elastomer composition; that is, such that the sum of the inter-wire distances is greater than or equal to the wire diameter. The inter-wire distance of a layer is defined, on a section of the cable perpendicular to the main axis of the cable, as the shortest average distance between two adjacent wires in the layer. Thus, the inter-wire distance is calculated by dividing the sum of the inter-wire distances by the number of spaces separating the wires in the layer.In other words, a layer can be desaturated when the inter-wire distance is greater than or equal to 5 µm.

[0017] Preferably, the inter-wire distance I3 of the outer layer of the inner strand or strand is greater than or equal to 15 µm, more preferably greater than or equal to 35 µm, even more preferably greater than or equal to 50 µm and very preferably greater than or equal to 60 µm.

[0018] Preferably, the inter-wire distance I3' of the outer layer of each outer strand is greater than or equal to 15 µm, more preferably greater than or equal to 35 µm, even more preferably greater than or equal to 50 µm and very preferably greater than or equal to 60 µm.

[0019] Preferably, the inter-wire distance of the outer layer of each strand is less than or equal to 100 µm.

[0020] In contrast, a saturated layer of wires is such that there is not enough space between the metal wires to allow the passage of an elastomer composition, i.e. such that the sum of the inter-wire distances is strictly less than the wire diameter.

[0021] In the invention, the cable has two layers of strands, that is to say, it comprises an assembly consisting of two layers of strands, no more and no less, that is to say, the assembly has two layers of strands, not one, not three, but only two.

[0022] By directly in contact with the theoretical outer layer, we mean that no sheath is arranged between the inner layer and the theoretical outer layer.

[0023] By elastomeric composition or elastomeric composition, we mean that the composition includes at least one elastomer or rubber (the two terms being synonymous) and at least one other component.

[0024] The inner layer of the cable is surrounded by an elastomeric composition with a thickness G and then it is surrounded by an outer layer.

[0025] The cable according to the invention exhibits improved penetrability compared to a cable of the examples in WO2011000963, which is not penetrated due to the absence of elastomeric composition between the inner and outer layers. The inventors of the invention hypothesize that this initial R2 / Rt ratio, ranging from 1.02 to 1.25, provides sufficient thickness of elastomeric composition to infiltrate the inner strand and fill the gaps. Furthermore, the desaturation of the outer layers allows the elastomeric composition to penetrate, on the one hand, between the outer strands and, on the other hand, between the outer strands and the inner strand(s), thus pushing the elastomeric composition from the sheath into the inner strand(s) to penetrate the central capillary.Thus, by using a final step that brings the outer strands closer to the inner layer, the diameter of the cable can be reduced while making it very well penetrated.

[0026] Advantageously, the internal strand or strands are cylindrically layered.

[0027] Advantageously, each outer strand has cylindrical layers.

[0028] Advantageously, each inner and outer strand has cylindrical layers. Recall that such cylindrical layers are obtained when the different layers of a strand are wound at different pitches and / or when the winding directions of these layers differ from one layer to another. A strand with cylindrical layers is highly penetrable, unlike a strand with tightly packed layers, in which the pitch of all layers is equal and the winding directions of all layers are identical, which exhibits much lower penetrability.

[0029] It is well known that the pitch of a strand represents the length of that strand, measured parallel to the axis of the cable, at the end of which the strand with that pitch makes one complete turn around said axis of the cable. Similarly, the pitch of a wire represents the length of that wire, measured parallel to the axis of the strand in which it is located, at the end of which the wire with that pitch makes one complete turn around said axis of the strand.

[0030] The winding direction of a layer of strands or wires refers to the direction formed by the strands or wires relative to the axis of the cable or strand. The winding direction is commonly designated by the letter either Z or S.

[0031] The pitch, winding direction and diameters of the wires and strands are determined in accordance with ASTM D2969-04 of 2014.

[0032] Preferably, the strands do not undergo pre-formation.

[0033] Advantageously, the cable is metallic. By definition, a metallic cable is a cable made of wires consisting primarily (i.e., more than 50% of the wires) or entirely (100% of the wires) of a metallic material. Such a metallic cable is preferably made of steel, more preferably of pearlitic (or ferritic-pearlitic) carbon steel, hereinafter referred to as "carbon steel," or of stainless steel (by definition, steel containing at least 11% chromium and at least 50% iron). However, it is of course possible to use other steels or alloys.

[0034] When carbon steel is advantageously used, its carbon content (% by weight of steel) is preferably between 0.05% and 1.2%, especially between 0.4% and 1.1%; these contents represent a good compromise between the mechanical properties required for pneumatics and the feasibility of the wires.

[0035] The metal or steel used, whether carbon steel or stainless steel, may itself be coated with a metallic layer that improves, for example, the handling properties of the wire rope and / or its constituent elements, or the performance properties of the rope and / or the tire itself, such as adhesion, corrosion resistance, or resistance to aging. In a preferred embodiment, the steel used is coated with a layer of brass (a zinc-copper alloy) or zinc.

[0036] Preferably, the wires in the same layer of a predetermined strand (inner or outer) all have substantially the same diameter. Advantageously, the outer strands all have substantially the same diameter. By "substantially the same diameter," we mean that the wires or strands have the same diameter within industry tolerances.

[0037] Advantageously, the outer strands are wound helically around the inner strand with a pitch ranging from 40 mm to 100 mm and preferably from 50 mm to 90 mm.

[0038] In a first embodiment according to the invention, the outer layer of the cable is saturated.

[0039] By definition, a saturated cable layer is one in which the inter-strand spacing of the outermost strands is strictly less than 20 µm. The inter-strand spacing of the outermost layer of outermost strands is defined, on a cable section perpendicular to the main cable axis, as the shortest average distance between the circular envelopes in which two adjacent outermost strands are embedded. This cable construction ensures good architectural stability of the outermost layer, and the saturation of the outermost layer ensures that it comprises a relatively high number of outermost strands and therefore exhibits a relatively high breaking strength.

[0040] In contrast, a desaturated cable layer is such that the inter-strand distance of the outer strands is greater than or equal to 20 µm.

[0041] In a second embodiment according to the invention, L is less than or equal to the maximum number of external strands Lmax that can be arranged on the theoretical external layer having a helix radius Rt and L is such that the external layer is incompletely unsaturated.

[0042] By definition, an incompletely unsaturated layer is one in which there is insufficient space to add at least one (P+1)th strand of the same diameter as the P strands in the layer. In this case, there is insufficient space in the outer layer to add at least one (L+1)th outer strand of the same diameter as the L outer strands of the outer layer. Thus, this cable construction ensures good architectural stability of the outer layer, and the incomplete unsaturation of the outer layer ensures that it contains a relatively high number of outer strands and therefore exhibits a relatively high breaking strength.

[0043] A completely unsaturated layer, as opposed to an incompletely unsaturated layer, is one in which there is enough space to add at least one (P+1)th strand of the same diameter as the P strands of the layer, with several strands potentially in contact with each other. In this case, there is enough space in the outer layer to add at least one (L+1)th strand of the same diameter as the L outer strands of the outer layer.

[0044] Preferably, L is equal to the maximum number of outer strands Lmax that can be arranged on the theoretical outer layer having a helix radius Rt, and L is such that the outer layer is incompletely unsaturated. The outer layer comprises a high number of outer strands and therefore exhibits a relatively high breaking strength.

[0045] According to the invention, the thickness G of the elastomeric composition sheath is strictly greater than 0 mm and preferably greater than or equal to 0.01 mm. The greater the thickness G of the elastomeric composition, the better the penetrability into the inner layer.

[0046] Advantageously, the thickness G of the elastomeric sheath is less than or equal to 0.80 mm, preferably less than or equal to 0.60 mm, and more preferably less than or equal to 0.52 mm. This thickness optimizes the penetrability of the inner layer while limiting the outer diameter of the cable.

[0047] Advantageously, the elastomeric composition comprises an elastomer selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

[0048] Preferably, the elastomeric composition comprises an elastomer selected from the group consisting of natural rubber, synthetic polyisoprenes, isoprene copolymers, and mixtures of these elastomers.

[0049] Preferably, the elastomer composition also includes a vulcanization system and a filler. More preferably, the elastomer is diene.

[0050] Preferably, the elastomeric composition includes carbon black as a reinforcing filler.

[0051] Advantageously, K=1, 2, 3 or 4, preferably K=1, 2 or 3 and more preferably K=1 or 3.

[0052] Advantageously, L=6, 7, 8, 9 or 10, preferably L=6, 7, 8 or 9, and more preferably L=6 or 9.

[0053] In the first variant, K=1 and L=6. In the cable where K=1, the most severe transverse forces are those exerted by the outer strands on the inner strand. Here, the presence of the elastomeric composition will relieve the contact pressures on the inner strand while ensuring good penetration of the latter.

[0054] In a second variant, K=2 and L=7 or 8, and preferably K=2 and L=8.

[0055] In a third variant, K=3 and L=7, 8 or 9, preferably K=3, L=9.

[0056] In a fourth variant, K=4 and L=7, 8, 9 or 10, preferably K=4, L=9 or 10.

[0057] In embodiments not conforming to the invention, particularly those where K=3 or 4, there is a risk of very high propagation of corrosive agents between the K=3 or 4 internal strands that define a central capillary highly conducive to their propagation along the cable, when the cable is insufficiently penetrated. This drawback can be overcome by the sheath around the K internal strands, which makes them penetrable through the elastomer composition. This sheath prevents corrosive agents from accessing the central capillary, which is itself penetrated, and thus prevents the propagation of these corrosive agents along the cable.

[0058] In cables where K > 1, the most severe transverse forces acting on the cable when it is under tension are the transverse forces acting between the inner strands. In the prior art, cables with an architecture where K > 1 and a number of outer strands are known, such that the outer layer of the cable is saturated to maximize the breaking strength by adding the maximum number of outer strands. Here, thanks to the desaturation of the outer layers of the strands, the cable exhibits, on the one hand, spaces between the outer strands allowing the passage of the elastomer composition and thus making the cable less susceptible to corrosion.Furthermore, although the number of outer strands is reduced, the desaturation of the outer layer of the strands allows the elastomeric compound to penetrate, on the one hand, between the outer strands and, on the other hand, to push the elastomeric compound of the sheath between the inner strands, thus forming a cushion of elastomeric compound that at least partially absorbs the transverse forces exerted between the inner strands. Therefore, compared to a similar cable with a saturated outer layer, improved corrosion resistance is achieved. Internal strand of the cable according to the invention

[0059] In a preferred embodiment, Q > 1, preferably Q = 2, 3, or 4. If Q were equal to 1, there would be a risk that, under repeated compressive stresses applied to the cable, the inner wire of the inner strand would radially pull out of the inner strand and even out of the cable. This risk is reduced by the presence of multiple wires in the inner layer of the inner strand (Q > 1), as the compressive stresses are then distributed over the plurality of wires in the inner layer.

[0060] Advantageously, N = 7, 8, 9 or 10.

[0061] In a first variant, Q=2 and N=7 or 8, preferably Q=2, N=7.

[0062] In a second variant, Q=3 and N=7, 8 or 9, preferably Q=3, N=8.

[0063] In a third variant, Q=4 and N=7, 8, 9 or 10, preferably Q=4, N=9.

[0064] Advantageously, each internal wire of the inner strand has a diameter d1 equal to the diameter d3 of each external wire of the inner strand. Thus, the same wire diameter is preferentially used on the inner and outer layers of the inner strand, which limits the number of different wires to be managed during cable manufacturing. External strands of the cable according to the invention

[0065] Advantageously, N' = 7, 8, 9 or 10.

[0066] In a first variant, Q'=2 and N'=7 or 8, preferably Q'=2, N'=7.

[0067] In a second variant, Q'=3 and N'=7, 8 or 9, preferably Q'=3, N'=8.

[0068] In a third variant, Q'=4 and N'=7, 8, 9 or 10, preferably Q'=4, N'=9.

[0069] Advantageously, each inner wire of the outer strand has a diameter d1' equal to the diameter d3' of each outer wire of the outer strand. Thus, the same wire diameter is preferentially used on the inner and outer layers of the outer strand, which limits the number of different wires to be managed during cable manufacturing.

[0070] Advantageously, Q=3 and N=8, each internal metal wire of each internal strand has a diameter d1 equal to the diameter d3 of each external wire of each internal strand, Q'= 3 and N'=8, each internal metal wire of each external strand has a diameter d1' equal to the diameter d3' of each external wire of each external strand, and d1=d3=d1'=d3'.

[0071] Advantageously, each metal wire has respectively a diameter d1, d1', d3, d3' ranging from 0.10 mm to 0.60 mm, preferably from 0.12 mm to 0.50 mm and more preferably from 0.15 mm to 0.42 mm. METHOD FOR MANUFACTURING THE CABLE ACCORDING TO THE INVENTION

[0072] Another object of the invention is a method for manufacturing a two-layer multi-strand cable according to claim 11.

[0073] Advantageously, the helical assembly steps of the K≥1 internal strands and the L>1 external strands around the internal layer of the cable are done by wiring.

[0074] Advantageously, the means used to bring the outer layer of the cable closer to the circle in which the inner layer of the cable is circumscribed are, for example, made up of two rows of rollers mounted opposite each other but offset and between which the cable is passed.

[0075] In one embodiment, one of the rows is mobile and can be brought closer to the fixed row so that the cable undergoes a succession of bending.

[0076] In another embodiment, the rows of rollers are mobile around the axis of the cable. REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0077] Another object of the invention is a reinforced product comprising an elastomeric matrix and at least one cable as defined above.

[0078] Advantageously, the reinforced product comprises one or more cables according to the invention embedded in the elastomeric matrix, and in the case of several cables, the cables are arranged side by side along a main direction. PNEUMATIC ACCORDING TO THE INVENTION

[0079] Another object of the invention is a pneumatic tire comprising at least one cable or reinforced product as defined above.

[0080] Preferably, the tire comprises a carcass reinforcement anchored in two beads and radially surmounted 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 cord as defined above.

[0081] In a preferred embodiment, the top 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.

[0082] The cable is particularly intended for industrial vehicles chosen from among 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 construction equipment type vehicles. Thus, the tire has a dimension in which the diameter, in inches, of the rim seat on which the tire is intended to be mounted is greater than or equal to 40 inches.

[0084] The invention will be better understood upon reading the following examples, given solely as non-limiting examples and made with reference to the drawings in which: there figure 1 is a cross-sectional view perpendicular to the circumferential direction of a tire according to the invention; the figure 2 is a detailed view of zone II of the figure 1 ; there figure 3 is a cross-sectional view of a reinforced product according to the invention; the figure 4 is a schematic cross-sectional view perpendicular to the cable axis (assumed to be straight and at rest) of a cable (50) according to a first embodiment of the invention; the figure 5 is a view analogous to that of the figure 4 of a cable (60) according to a second embodiment of the invention; the figure 6 is a view analogous to that of the figure 4 of a cable (70) according to a third embodiment of the invention; the figure 7 is a view analogous to that of the figure 4of a cable (80) according to a fourth embodiment of the invention; the figures 8 And 9 are schematic representations of a cable manufacturing installation (50) according to a first embodiment of the invention; the Figure 10 is a schematic representation of step 400 of bringing the outer layer towards the inner layer of a cable (50) according to a first embodiment of the invention; and the figure 11 is a photograph of a test cable (T1) and a cable (50) according to a first embodiment of the invention. EXAMPLE OF A PNEUMATIC TIRE ACCORDING TO THE INVENTION

[0085] In the Figures 1 And 2 , we have represented a coordinate system X, Y, Z corresponding to the usual orientations respectively axial (X), radial (Y) and circumferential (Z) of a tire.

[0086] The "circumferential median plane" M of the tire is the plane that is normal to the axis of rotation of the tire and that is equidistant from the annular reinforcement structures of each bead.

[0087] We have represented on the Figures 1 And 2 a tire according to the invention and designated by the general reference 10.

[0088] Tire 10 is for heavy-duty vehicles such as construction equipment, for example, dump trucks. Tire 10 has a size of 53 / 80R63.

[0089] The tire 10 comprises a crown 12 reinforced by a crown reinforcement 14, two sidewalls 16, and two bead 18, each bead 18 being reinforced with an annular structure, here a bead 20. The crown reinforcement 14 is radially surmounted by a tread 22 and joined to the bead 18 by the sidewalls 16. A carcass reinforcement 24 is anchored in the two bead 18 and is here wrapped around the two beads 20. It includes a gusset 26 facing outwards from the tire 20, which is shown here mounted on a rim 28. The carcass reinforcement 24 is radially surmounted by the crown reinforcement 14.

[0090] The carcass reinforcement 24 comprises at least one carcass layer 30 reinforced by radial carcass cables (not shown). The carcass cables are arranged substantially parallel to each other and extend from one bead 18 to the other so as to form an angle 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 bead 18 and passes through the middle of the apex reinforcement 14).

[0091] The tire 10 also includes a sealing layer 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 layer 30 from air diffusion from the space inside the tire 10.

[0092] 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 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.

[0093] The protective frame 36 comprises first and second protective layers 42, 44 comprising protective metal cables, the first layer 42 being arranged radially inside the second layer 44. Optionally, the protective metal cables make an angle of at least 10°, preferably from 10° to 35° and preferably from 15° to 30° with the circumferential direction Z of the tire.

[0094] The working frame 38 comprises first and second working layers 46, 48, the first layer 46 being arranged radially inside the second layer 48. Each layer 46, 48 comprises at least one cable 50. Optionally, the working wire cables 50 are crossed from one working layer to the other and make an angle of no more than 60°, preferably from 15° to 40° with the circumferential direction Z of the tire.

[0095] The additional reinforcement 40, also called the limiting block, whose function is to partially take over the mechanical stresses of inflation, includes, for example and in a way known per se, additional metallic reinforcement elements, for example such as described in FR 2 419 181 or FR 2 419 182 making an angle of at most equal to 10°, preferably going from 5° to 10° with the circumferential direction Z of the tire 10. EXAMPLE OF A REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0096] We have represented on the figure 3 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 elastomeric matrix 102.

[0097] On the figure 3 The elastomeric matrix 102 and the cables 50 were represented in an X, Y, Z coordinate system in which the Y direction is the radial direction and the X and Z directions are the axial and circumferential directions. On the figure 3 , the reinforced product 100 comprises several cables 50 arranged side by side along the main direction X and extending parallel to each other within the reinforced product 100 and collectively embedded in the elastomeric matrix 102. CABLE ACCORDING TO A FIRST EMBODIMENT OF THE INVENTION

[0098] We have represented on the figure 4 The cable 50 according to a first embodiment of the invention. The cable 50 is shown before step 400 of bringing the outer layer CE of the cable closer to the circle in which the inner layer CI of the cable is circumscribed.

[0099] Cable 50 is metallic and is of the multi-strand, two-layer cylindrical type. Therefore, it is understood that the layers of strands constituting cable 50 are two in number, no more, no less.

[0100] Cable 50 comprises an inner layer CI consisting of K≥1 inner strand(s) TI. In this case, K=1, 2, 3, or 4, preferably K=1, 2, or 3, and more preferably K=1 or 3, here K=3. The inner layer CI is surrounded by an elastomeric composition of thickness G, thus forming the sheathed inner layer CIG. The outer layer CE consists of L>1 outer strands TE wound around the sheathed inner layer CIG of the cable, having a helix radius R2. In this case, L=6, 7, 8, 9, or 10, preferably L=6, 7, 8, or 9, and more preferably L=6 or 9, and in this case L=9. R2 is here equal to 2.50 mm.

[0101] The thickness G of the elastomeric composition is such that the ratio R2 / Rt ranges from 1.02 to 1.25, where Rt is the helix radius of the theoretical outer layer CET obtained when the inner layer CI is in direct contact with the theoretical outer layer CET. Here, R2 = 2.40 and R2 / Rt = 2.40 / 2.28 = 1.05.

[0102] The cable 50 is finally obtained by a process comprising a step 500 to bring the outer layer CE of the cable closer to the circle in which the inner layer CI of the cable is circumscribed such that the ratio R2 / Rt goes from 1.00 to 1.10. Here R2=2.32 and R2 / Rt=2.33 / 2.28=1.02.

[0103] Cable 50 also includes an unshown F fret made of a single fret wire. Internal strands TI of cable 50

[0104] Each internal strand TI is two-layered and comprises an inner layer C1 consisting of Q= 2, 3 or 4 internal metal wires F1 and an outer layer C3 consisting of N external metal wires F3 wound around the inner layer C1.

[0105] Here Q=3.

[0106] N = 7, 8, 9 or 10, here N = 8.

[0107] The outer layer C3 of each inner strand TI is desaturated and incompletely unsaturated. Being desaturated, the inter-wire spacing of the outer layer of each inner strand is greater than or equal to 15 µm, more preferably greater than or equal to 35 µm, even more preferably greater than or equal to 50 µm, and very preferably greater than or equal to 60 µm, and here equal to 66 µm. The sum SI3 of the inter-wire spacings I3 of the outer layer of each inner strand is greater than or equal to the diameter d3 of the outer wires of the outer layer of each inner strand. Here, the sum SI3 = 0.53 mm, a value greater than d3 = 0.35 mm.

[0108] Each inner and outer wire of each internal strand TI has a diameter d1 and d3 respectively. The diameter of the inner wire d1 and outer wire d3 of each internal strand TI ranges from 0.10 mm to 0.60 mm, preferably from 0.12 mm to 0.50 mm, and more preferably from 0.14 mm to 0.42 mm. Here d1 = d3 = 0.35 mm. External strands TE of cable 50

[0109] Each external strand TE is two-layered and includes an inner layer C1' consisting of Q'= 2, 3 or 4 internal metal wires F1' and an outer layer C3' consisting of N' external metal wires F3' wound around the inner layer C1'.

[0110] Here Q'=3.

[0111] N' = 7, 8, 9 or 10, here N' = 8.

[0112] The outer layer C3' of each outer strand TE is desaturated. Being desaturated, the inter-wire spacing I3' of the outer layer C3' separating the N' outer wires on average is greater than or equal to 15 µm, more preferably greater than or equal to 35 µm, even more preferably greater than or equal to 50 µm, and very preferably greater than or equal to 60 µm, and here equal to 66 µm. The sum SI3' of the inter-wire spacings I3' of the outer layer of each outer strand is greater than or equal to the diameter d3 of the outer wires of the outer layer of each outer strand. Here, the sum SI3' = 0.53 mm, a value greater than d3' = 0.35 mm.

[0113] Each inner and outer wire of each external strand TE has a diameter d1' and d3' respectively. The diameter of each inner wire d1' and outer wire d3' of each external strand TE ranges from 0.10 mm to 0.60 mm, preferably from 0.12 mm to 0.50 mm, and more preferably from 0.14 mm to 0.42 mm. Here d1' = d3' = 0.35 mm.

[0114] Cable 50 is such that Q=3 and N=8, each internal metal wire F1 of each internal strand TI has a diameter d1 equal to the diameter d3 of each external wire F3 of each internal strand TI; Q'=3 and N'=8, each internal metal wire of each external strand TE has a diameter d1' equal to the diameter d3' of each external wire of each external strand TE; and d1=d3=d1'=d3'. Here d1=d3=d1'=d3'=0.35 mm.

[0115] The outer CE layer of the cable is desaturated. The average inter-strand distance E between two adjacent outer strands TE is therefore greater than or equal to 20 µm. Preferably, the average inter-strand distance E between two adjacent outer strands TE is greater than or equal to 40 µm, and more preferably to 50 µm. Here, the inter-strand distance E is equal to 125 µm.

[0116] Each wire has a tensile strength, denoted Rm, such that 2500 ≤ Rm ≤ 3100 MPa. The steel used for these wires is said to be SHT grade ("Super High Tensile"). Other wires can be used, for example, lower grade wires, such as NT grade ("Normal Tensile") or HT grade ("High Tensile"), as well as higher grade wires, such as UT grade ("Ultra Tensile") or MT grade ("Mega Tensile"). METHOD FOR MANUFACTURING THE CABLE ACCORDING TO THE INVENTION

[0117] We will now describe an example of a manufacturing process for 50-strand multi-strand cable with reference to figures 8 And 9 .

[0118] Each internal strand described above is manufactured using known processes comprising the following steps, preferably carried out in-line and continuously: firstly, a first assembly step by wiring the Q=2, 3 or 4 internal wires F1 of the internal layer C1 at pitch p1 and in the Z direction to form the internal layer C1 at a first assembly point; followed by a second assembly step by wiring or twisting the N external wires F3 around the Q internal wires F1 of the internal layer C1 at pitch p3 and in the Z direction to form the external layer C3 at a second assembly point; preferably a final balancing step of the twists.

[0119] In step 100, internal strands TI are assembled in a helix K≥1 by wiring to form an internal layer CI of the cable.

[0120] In a step 200, the inner layer CI is surrounded by an elastomeric composition having a thickness G to form an inner sheathed layer CIG, the thickness G of elastomeric composition being such that the ratio R2 / Rt goes from 1.02 to 1.25 with Rt being the helix radius of the theoretical outer layer CET obtained when the inner layer CI is directly in contact with the theoretical outer layer CET.

[0121] Each outer strand described above is manufactured using known processes comprising the following steps, preferably carried out in-line and continuously: firstly, a first assembly step by wiring the Q'= 2, 3 or 4 internal wires F1' of the internal layer C1' at the pitch p1' and in the Z direction to form the internal layer C1' at a first assembly point; followed by a second assembly step by wiring or twisting the N' external wires F3' around the Q' internal wires F1' of the internal layer C1' at the pitch p3' and in the Z direction to form the external layer C3' at a second assembly point; preferably a final balancing step of the twists.

[0122] By "torsional balancing", we mean here, in a way well known to those skilled in the art, the cancellation of residual torsional couples (or elastic torsional return) acting on each wire of the strand, in the intermediate layer as well as in the outer layer.

[0123] After this final twist balancing stage, the strand manufacturing process is complete. Each strand is wound onto one or more receiving reels for storage, prior to the subsequent assembly operation of wiring the individual strands to obtain the multi-strand cable.

[0124] In step 300, external strands TE are assembled in a helix L>1 by wiring around the internal layer CI of the cable. In step 400, means 500 are used to bring the external layer CE of the cable closer to the circle in which the internal layer CI of the cable is circumscribed such that the ratio R2 / Rt goes from 1.00 to 1.10.

[0125] This step 400 is described with reference to the Figure 10 .

[0126] The means used to bring the outer layer CE of the cable closer to the circle in which the inner layer CI of the cable is circumscribed consist, for example, of two rows of rollers mounted opposite each other but offset, between which the cable is passed. Each row contains between 6 and 8 rollers. One of the rows is movable and can be brought closer to the fixed row so that the cable undergoes a series of bends. These rows of rollers can be fixed or movable around the axis of the cable.

[0127] Thus, the cable undergoes a series of bends that reduce its diameter, as illustrated in Figure 10 .

[0128] L is equal to the maximum number of outer strands (OT) Lmax that can be arranged on the theoretical outer layer (OT) having a helix radius Rt, and L is such that the outer layer (OT) is incompletely unsaturated. Here Lmax = 9 and L = Lmax = 9.

[0129] The thickness G of the elastomeric sheath is strictly greater than 0 mm and preferably greater than or equal to 0.01 mm, and the thickness G is less than or equal to 0.80 mm, preferably less than or equal to 0.60 mm and more preferably less than or equal to 0.52 mm. Here, G = 0.05 mm.

[0130] The elastomeric composition includes a vulcanization system, a filler, and a diene elastomer.

[0131] The elastomeric composition used is a conventional diene elastomer(s) composition for tires, based on natural (peptized) rubber and N330 carbon black (65 pc), also containing the following usual additives: sulfur (7 pc), sulfenamide accelerator (1 pc), ZnO (8 pc), stearic acid (0.7 pc), antioxidant (1.5 pc), cobalt naphthenate (1.5 pc) (pc meaning parts by weight per hundred parts of elastomer); the E10 modulus of the elastomeric coating composition is approximately 10 MPa.

[0132] Optionally, in a final assembly step, the fret F is wound with a pitch of pf in the direction S around the assembly previously obtained.

[0133] The cable is then incorporated by calendering into composite fabrics made of a known composition based on natural rubber and carbon black as a reinforcing filler, conventionally used for manufacturing the 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 expanding oil, cobalt naphthenate as an adhesion promoter, and finally a vulcanization system (sulfur, accelerator, ZnO).

[0134] The composite fabrics reinforced by these cables have an elastomeric matrix composed of two thin layers of elastomeric material superimposed on either side of the cables, with thicknesses ranging from 1 mm to 4 mm respectively. The calendering pitch (the spacing of the cables within the elastomeric fabric) ranges from 4 mm to 8 mm.

[0135] These composite fabrics are then used as a working layer in the crown reinforcement during the tire manufacturing process, the steps of which are otherwise known to those skilled in the art. CABLE ACCORDING TO A SECOND EMBODIMENT OF THE INVENTION

[0136] We have represented on the figure 5A cable 60 according to a second embodiment of the invention. The cable 60 is shown before step 400, which brings the outer layer CE of the cable closer to the circle in which the inner layer CI of the cable is circumscribed. Elements analogous to the first embodiment are designated by identical reference numerals.

[0137] Unlike the first embodiment described above, cable 60 according to the second embodiment is such that K=1 and L=6. CABLE ACCORDING TO A THIRD IMPLEMENTATION OF THE INVENTION

[0138] We have represented on the figure 6 a cable 70 according to a third embodiment of the invention after step 400 of bringing the outer layer CE of the cable closer to the circle in which the inner layer CI of the cable is circumscribed.

[0139] Unlike the first embodiment of cable 50 described previously, cable 70 according to the third embodiment is such that K=2 and L=9. CABLE ACCORDING TO A FOURTH IMPLEMENTATION OF THE INVENTION

[0140] We have represented on the figure 7 a cable 80 according to a fourth embodiment of the invention after step 400 of bringing the outer layer CE of the cable closer to the circle in which the inner layer CI of the cable is circumscribed.

[0141] Unlike the first embodiment of cable 50 described previously, cable 80 according to the fourth embodiment is such that K=4 and L=10.

[0142] Table 1 below summarizes the characteristics for the different cables 50, 51, 60, 70 and 80. Table 1 Cables 50 60 70 80 51 TI Q / N 3 / 8 3 / 8 3 / 8 3 / 8 3 / 8 d1 / d3 0,35 / 0,35 0,35 / 0,35 0,35 / 0,35 0,35 / 0,35 0,35 / 0,35 direction C1 / step p1 (mm) Z / 7,7 Z / 7,7 Z / 7,7 Z / 7,7 Z / 7,7 direction C3 / not p3 (mm) Z / 15.4 Z / 15.4 Z / 15.4 Z / 15.4 Z / 15.4 I3(µm) / SI3(mm) 66 / 0,53 66 / 0,53 66 / 0,53 66 / 0,53 66 / 0,53 Sheath G (mm) 0,05 0,11 0,06 0,08 0,01 YOU Q' / N' 3 / 8 3 / 8 3 / 8 3 / 8 3 / 8 d1' / d3' 0,35 / 0,35 0,35 / 0,35 0,35 / 0,35 0,35 / 0,35 0,35 / 0,35 direction C1' / not p1' (mm) Z / 7,7 Z / 7,7 Z / 7,7 Z / 7,7 Z / 7,7 direction C3' / not p3' (mm) Z / 15.4 Z / 15.4 Z / 15.4 Z / 15.4 Z / 15.4 I3'(µm) / SI3'(mm) 66 / 0,53 66 / 0,53 66 / 0,53 66 / 0,53 66 / 0,53 Cable direction / pi / pe S / S 40 / 80 S / inf / 60 S / S 40 / 80 S / S 40 / 80 S / S 40 / 80 K 3 1 2 4 3 L 9 6 9 10 9 Lmax 9 6 9 10 9 D (mm) 6,11 4,59 5,91 6,57 6,04 E (µm) 125 112 58 59 98 R2 before step 400 2,40 1,59 2,23 2,48 2,40 R2 after step 400 2,33 1,57 2,23 2,48 2,30 RT 2,28 1,46 2,17 2,48 2,28 R2 / Rt before step 400 1,05 1,09 1,03 1,03 1,05 R2 / Rt after step 400 1,02 1,08 1,03 1,03 1,00 COMPARATIVE TESTS AIRTIGHTNESS TEST

[0143] This test determines the longitudinal air permeability of the cables being tested by measuring the volume of air passing through a test specimen under constant pressure over a given time. The principle of such a test, well known to those skilled in the art, is to demonstrate the effectiveness of a cable treatment to make it airtight; it has been described, for example, in ASTM D2692-98.

[0144] This test is performed on cables fresh from manufacturing and not aged. The raw cables are first coated externally with an elastomeric composition known as the coating. For this, a series of 10 cables arranged parallel to each other (inter-cable distance: 20 mm) is placed between two layers or "skims" (two 80 x 200 mm rectangles) of a raw diene elastomeric composition, each skim being 5 mm thick; the whole assembly is then secured in a mold, each cable being held under sufficient tension (for example, 3 daN) to guarantee its straightness during placement in the mold, using clamping modules; then vulcanization (curing) takes place for approximately 10 to 12 hours at a temperature of about 120°C and under a pressure of 15 bar (rectangular piston of 80 x 200 mm).After which, the whole thing is removed from the mold and 10 test specimens of the coated cables are cut, in the form of parallelepipeds with dimensions of 7x7x60 mm, for characterization.

[0145] A conventional diene elastomer composition for tires, based on natural (peptized) rubber and N330 carbon black (65 parts per cent), is used as the elastomeric coating composition, in addition to the following usual additives: sulfur (7 parts per cent), sulfenamide accelerator (1 part per cent), ZnO (8 parts per cent), stearic acid (0.7 parts per cent), antioxidant (1.5 parts per cent), cobalt naphthenate (1.5 parts per cent) (parts per cent meaning parts by weight per hundred parts of elastomer); the E10 modulus of the elastomeric coating composition is approximately 10 MPa.

[0146] The test is performed on a 6 cm length of cable, coated by its surrounding elastomeric composition (or coating elastomeric composition) in its cured state, as follows: air is introduced into the cable inlet under a pressure of 1 bar, and the volume of air exiting is measured using a flow meter (calibrated, for example, from 0 to 500 cm³ / min). During the measurement, the cable sample is held in a compressed airtight seal (for example, a dense foam or rubber seal) such that only the quantity of air passing through the cable from one end to the other, along its longitudinal axis, is taken into account by the measurement; the airtightness of the seal itself is checked beforehand using a solid elastomeric composition test specimen, i.e., without cable.

[0147] The average measured airflow (average over the 10 test specimens) is lower the higher the longitudinal impermeability of the cable. Since the measurement is made with an accuracy of ± 0.2 cm³ / min, measured values ​​less than or equal to 0.2 cm³ / min are considered zero; they correspond to a cable that can be described as airtight (completely airtight) along its axis (i.e., in its longitudinal direction).

[0148] Table 2 summarizes the characteristics of the T1 and T2 test cables and the EDT state-of-the-art cable (example 3 of WO2016051669). Table 2 Cables T1 T2 EDT TI Q / N 3 / 8 3 / 8 2 / 9 d1 / d3 0,35 / 0,35 0,35 / 0,35 0,48 / 0,48 direction C1 / step p1 (mm) Z / 7,7 Z / 7,7 Z / 7,7 direction C3 / not p3 (mm) Z / 15.4 Z / 15.4 Z / 15.4 13(µm) / SI3(mm) 66 / 0,53 66 / 0,53 0 Sheath G (mm) 0 0 0 YOU Q' / N' 3 / 8 3 / 8 3 / 8 d1' / d3' 0,35 / 0,35 0,35 / 0,35 0,28 / 0,37 direction C1' / not p1' (mm) Z / 7,7 Z / 7,7 Z / 7,7 direction C3' / not p3' (mm) Z / 15.4 Z / 15.4 Z / 15.4 I3'(µm) / SI3'(mm) 66 / 0,53 66 / 0,53 0 K 3 4 1 L 9 10 6 Lmax 9 10 6 D (mm) 6,02 6,40 4,60 E (µm) 95 59 70 R2 2,28 2,48 1,64 RT 2,28 2,48 1,64 R2 / Rt 1,00 1,00 1,00

[0149] Tables 3 to 5 below summarize the permeability test results for the different test cables T1 and T2, the prior art cable EDT, and the cables according to the invention 50, 60 and 80. The results of these tests are given on a scale of 100. Thus, a result of 100 in any of these tests means that the tested cable has maximum penetrability, i.e. that the cable is totally airtight. Table 3 Cables 50 50-1 50-2 50-3 K / L 3 / 9 3 / 9 3 / 9 3 / 9 3 / 9 Q / N / Q' / N' 3 / 8 / 3 / 8 3 / 8 / 3 / 8 3 / 8 / 3 / 8 3 / 8 / 3 / 8 3 / 8 / 3 / 8 R2 before step 400 (mm) 2,28 2,40 2,45 2,57 2,62 R2 after step 400 (mm) - 2,32 2,35 2,47 2,42 Rt (mm) 2,28 2,28 2,28 2,28 2,28 R2 / Rt before step 400 1 1,05 1,07 1,13 1,15 R2 / Rt after step 400 1 1,02 1,03 1,08 1,06 G (mm) 0 0,04 0,07 0,19 0,14 Penetration (base 100, cable 100% penetrated) 0 96 97 97 97 Table 4 Cables EDT 60 K / L 1 / 6 1 / 6 Q / N / Q' / N' 2 / 9 / 3 / 8 3 / 8 / 3 / 8 R2 before step 400 (mm) 1,64 1,59 R2 after step 400 (mm) - 1,57 Rt (mm) 1,64 1,46 R2 / Rt before step 400 1 1,09 R2 / Rt after step 400 - 1,08 G (mm) 0 0,11 Penetration (base 100, cable 100% penetrated) 95 98 Table 5 Cables T2 80 80-1 K / L 4 / 10 4 / 10 4 / 10 Q / N / Q' / N' 3 / 8 / 3 / 8 3 / 8 / 3 / 8 3 / 8 / 3 / 8 R2 before step 400 (mm) 2,48 2,56 2,63 R2 after step 400 (mm) - 2,56 2,63 Rt (mm) 2,48 2,48 2,48 R2 / Rt before step 400 1 1,03 1,06 R2 / Rt after step 400 - 1,03 1,06 G (mm) 0 0,08 0,15 Penetration (base 100, cable 100% penetrated) 0 91 95

[0150] It is noted that cable 50 according to the invention exhibits significantly greater penetration than the control cable T1, and therefore a penetration close to 100%, solely due to the R2 / Rt ratio conforming to the invention. This is also evident on the figure 11 , that the central capillary is totally penetrated for cable 50 while that of T1 is not, the arrows indicating the areas where there is a lack of elastomeric composition.

[0151] Similarly, cable 60 according to the invention exhibits superior penetrability compared to the prior art cable EDT.

[0152] Similarly, cable 80 according to the invention exhibits a significantly higher penetration capability than that of the T2 test cable.

[0153] Tables 3 to 5 show that, for various cable constructions, the penetration of the elastomeric composition into the cable, and therefore the accessibility of the internal strand by this elastomeric composition, is significantly improved for an R2 / Rt ratio according to the invention thanks to the presence of the sheath of thickness G compared to the control cables for which R2 / Rt=1.

[0154] Of course, the invention is not limited to the embodiments described above.

[0155] For reasons of industrial feasibility, cost and overall performance, it is preferable to implement the invention with linear wires, i.e. straight, and with a conventional circular cross-section.

[0156] It will also be possible to combine the characteristics of the different embodiments described or envisaged above, provided that they are compatible with each other.

Claims

1. Two-layer multi-strand cord (50), characterized in that it comprises: - an internal layer (CI) of the cord made up of K≥1 internal strand(s) (TI), the or each internal strand (TI) being a two-layer (C1, C3) strand and comprising: • an internal layer (C1) made up of Q= 2, 3 or 4 internal metallic threads (F1), and • an external layer (C3) made up of N external metallic threads (F3) of diameter d3 wound around the internal layer (C1), - an external layer (CE) of the cord made up of L>1 external strands (TE) wound around the internal layer (CI) of the cord, having a helix radius R2, each external strand (TE) being a two-layer (C1', C3') strand and comprising: • an internal layer (C1') made up of Q'=2, 3 or 4 internal metallic threads (F1'), and • an external layer (C3') made up of N' external metallic threads (F3') of diameter d3' wound around the internal layer (C1'), wherein: - the external layer (C3) of the or of each internal strand (TI) is desaturated so that the sum SI3 of the inter-thread distances I3 of the external layer of the or of each internal strand (TI) is greater than or equal to the diameter d3; - the external layer (C3') of each external strand (TE) is desaturated so that the sum SI3' of the inter-thread distances I3' of the external layer (C3') of each external strand (TE) is greater than or equal to the diameter d3'; - the cord (50) is obtained by a method comprising: - a step of manufacturing the sheathed internal layer (CIG) in which step the internal layer (CI) is surrounded with an elastomer composition having a thickness G and then by an external layer (CE), the thickness G of the elastomer composition being such that the ratio R2 / Rt ranges from 1.02 to 1.25, where Rt is the helix radius of the theoretical external layer (CET) obtained when the internal layer (CI) is directly in contact with the theoretical external layer (CET); and - a step (400) for bringing the external layer (CE) of the cord closer to the circle in which the internal layer (CI) of the cord is circumscribed so that the ratio R2 / Rt ranges from 1.00 to 1.10; wherein the sheath of elastomer composition is greater than or equal to 0.01 mm.

2. Cord (50) according to Claim 1, wherein the external layer (CE) of the cord is saturated so that the inter-strand distance of the external strands, defined, on a cross section of the cord perpendicular to the main axis of the cord (50), as being the shortest distance separating, on average, the circular envelopes in which two adjacent external strands (TE) are inscribed, is strictly less than 20 µm.

3. Cord (50) according to Claim 1, wherein L is equal to the maximum number of external strands (TE) Lmax that can be laid on the theoretical external layer (CET) having a helix radius Rt and L is such that the external layer (CE) is incompletely unsaturated.

4. Cord (50) according to any one of the preceding claims, wherein the thickness G of the sheath of elastomer composition is less than or equal to 0.80 mm, preferably less than or equal to 0.60 mm, and more preferably less than or equal to 0.52 mm.

5. Cord (50) according to any one of the preceding claims, wherein the elastomer composition comprises an elastomer selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and mixtures of these elastomers.

6. Cord (50) according to any one of the preceding claims, wherein K=1, 2, 3 or 4, and preferably K=1, 2 or 3 and more preferably K=1 or 3.

7. Cord (50) according to any one of the preceding claims, wherein L=6, 7, 8, 9 or 10 and preferably L=6, 7, 8 or 9 and more preferably L=6 or 9.

8. Cord (50) according to any one of the preceding claims, wherein N=7, 8, 9 or 10.

9. Cord (50) according to any one of the preceding claims, wherein N'=7, 8, 9 or 10.

10. Method of manufacturing a two-layer multi-strand cord (50), characterized in that: - in a step (100), K≥1 internal strand(s) (TI), are assembled by cabling or twisting into a helix to form an internal layer (CI) of the cord; the or each internal strand (TI) being a two-layer (C1, C3) strand and comprising: an internal layer (C1) made up of Q= 2, 3 or 4 internal metallic threads (F1), and an external layer (C3) made up of N external metallic threads (F3) of diameter d3 wound around the internal layer (C1), so that the sum SI3 of the inter-thread distances I3 of the external layer of the or of each internal strand (TI) is greater than or equal to the diameter d3; - in a step (200), the internal layer (CI) is surrounded with an elastomer composition having a thickness G, to form a sheathed internal layer (CIG), the thickness G of the elastomer composition being such that the ratio R2 / Rt ranges from 1.02 to 1.25, where Rt is the helix radius of the theoretical external layer (CET) obtained when the internal layer (CI) is directly in contact with the theoretical external layer (CET); - in a step (300), L>1 external strands (TE) are assembled by cabling or twisting into a helix around the internal layer (CI) of the cord, each external strand (TE) being a two-layer (C1', C3') strand and comprising: an internal layer (C1') made up of Q'=2, 3 or 4 internal metallic threads (F1'), and an external layer (C3') made up of N' external metallic threads (F3') of diameter d3' wound around the internal layer (C1'), so that the sum SI3' of the inter-thread distances I3' of the external layer (C3') of each external strand (TE) is greater than or equal to the diameter d3'; - in a step (400), means (500) are used for bringing the external layer (CE) of the cord closer to the circle in which the internal layer (CI) of the cord is circumscribed so that the ratio R2 / Rt ranges from 1.00 to 1.10; with the sheath of elastomer composition is greater than or equal to 0.01 mm.

11. Reinforced product (100), characterized in that it comprises an elastomer matrix (102) and at least one cord (50) according to any one of Claims 1 to 9.

12. Tyre (10), characterized in that it comprises at least one cord (50) according to any one of Claims 1 to 9 or a reinforced product according to Claim 11.