Multi-strand cable with two multi-strand layers

Abstract

The present invention relates to a multi-strand cable (50) having two multi-strand layers, the cable (50) comprising an inner layer (CI) of a cable composed of a multi-strand (M1) with X = 1, comprising a plurality of strands (T1) with K > 1 spirally wound around a main axis (A), each strand (T1) being a strand having at least two layers (C1, C3), and each strand (T1) being spirally wound around an axis (B); an outer layer (CE) of the cable composed of a plurality of multi-strands (M2) with Y > 1 wound around the inner layer (CI) of the cable, each multi-strand (M2) comprising a strand (T2) with L > 1 spirally wound around an axis (A'), each strand (T2) being a strand having at least two layers (C1', C3'), and the multi-strand (T2) being spirally wound around the main axis (A). The cable (50) has a structural elongation As such that As ≧ 1.0%.

Description

Technical Field

[0001] The present invention relates to cords and tires provided with these cords.

Background Art

[0002] Cords having a structure of (1+6)×(3+8) are known from the prior art as described in French Patent No. 2969181 (B). These cords comprise six strands helically wound around a single strand with a pitch of 60 mm. Each strand comprises an inner layer containing three inner wires helically wound with a pitch of 7.7 mm for a part thereof, and an outer layer containing eight outer wires helically wound around the inner layer with a pitch of 15.4 mm. The structural elongation of the cord is less than 0.2%, and the breaking force is 19,600 N.

[0003] These cords are hard cords, which have the advantage of relieving the tension acting on the working ply, but significantly increasing the circumferential rigidity of the structure. When arranged in an additional reinforcement, the sensitivity of the crown block to attack at the center of the tread increases.

[0004] Today, there is a need to develop new cords for application to crown plies, especially plies having an attachment angle of less than 10°, such as additional reinforcements. The purpose of this reinforcement is to relieve the tension of the working ply and improve the durability performance of the tire, particularly the fracture resistance.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present invention is a cord having a good compromise between rigidity and flexibility, having sufficient flexibility to reduce the rigidity of the crown block, but having a breaking force sufficient to withstand tensile stress loading.

Means for Solving the Problems

[0007] For this purpose, one subject of the present invention is a multi-strand element comprising a two-layer multi-strand element, and this cord is a cord inner layer composed of a multi-strand element of X = 1 comprising a plurality of strands (T1) of K> 1 spirally wound around a main axis, each strand being an inner layer composed of internal metal wires (plural possible) of Q1, and an outer layer composed of external metal wires of Q3 wound around the inner layer, having at least two layers, a cord inner layer, a cord outer layer composed of a plurality of multi-strand elements of Y> 1 wound around the cord inner layer, each multi-strand element comprising a strand of L> 1 spirally wound around an axis, each strand being an inner layer composed of internal metal wires (plural possible) of Q1', and an outer layer composed of external metal wires of Q3' wound around the inner layer, having at least two layers, a cord outer layer, comprising The multi-strand element is spirally wound around the main axis, The cord has a structural elongation As such that As ≧ 1.0%, and the structural elongation As is determined by applying ASTM standard D2969-04 (2014) to the cord to obtain a force-elongation curve, and is equal to the elongation (unit: %) corresponding to the intersection of the tangent to the elastic part along the elastic part of the force-elongation curve and the elongation axis of the force-elongation curve.

[0008] Thanks to this multi-strand cord configuration with a two-layer multi-strand element, the code according to the present invention provides sufficient structural elongation and sufficient metal mass for tensile flexibility, while at the same time making it possible to obtain a cord with thin wires in an elongated state for bending flexibility, in order to improve the compromise between shear in the polymer matrix, flexibility and the strength of the crown block, and as a result, to improve the compromise between breakage and attack performance.

[0009] The structural elongation As, which is a parameter well-known to those skilled in the art, is determined, for example, by applying ASTM standard D2969-04(2014) to the cord tested to obtain a force-elongation curve. As is derived from the obtained curve as the elongation (in %) corresponding to the intersection point between the tangent of the elastic part of the force-elongation curve and the elongation axis of the force-elongation curve. It should be recalled that the force-elongation curve includes a structural part, an elastic part, and a plastic part in the increasing direction of elongation. The structural part corresponds to the structural elongation of the cord resulting from the different strands and metal wires that make up the cord moving together. The elastic part corresponds to the elastic elongation resulting from the configuration of the cord, particularly the configuration of the angles of the various layers and the configuration of the diameters of the metal wires. The plastic part corresponds to the plastic elongation resulting from the plasticity of the metal wires (irreversible deformation beyond the elastic limit).

[0010] In the present invention, the cord comprises a two-layer multi-strand element, which means that it comprises an assembly composed of a single-layer multi-strand element with Y>1 wound around a single-layer multi-strand element, where the cord has neither more nor less than this. This assembly has a two-layer multi-strand element, meaning it has neither one layer nor three layers, but only two layers.

[0011] In the present invention, the multi-strand element has a single layer of strands, which means that it comprises an assembly having a single layer of strands, where the multi-strand element has neither more nor less than this. This assembly has a single layer of strands, meaning it has neither zero layers nor two layers, but only one layer.

[0012] In one embodiment, the internal multi-strand element of the cord is surrounded by a polymer composition and subsequently surrounded by an outer layer.

[0013] Advantageously, each strand has a cylindrical layer.

[0014] Advantageously, each strand within the multi-strand element has two layers, which means that each strand comprises an assembly composed of two layers of metal wires, neither more nor less, and this assembly has two layers of metal wires, not one layer or three layers, but only two layers. The outer layer of each strand contacts and wraps around the inner layer of that strand.

[0015] Very advantageously, each strand of the inner layer and each strand of the outer layer have a cylindrical layer. It will be recalled that such a cylindrical layer can be obtained when the various layers of the strand are wound at different pitches and / or when the winding directions of these layers are different for each layer. The strand with a cylindrical layer is very different from a strand with a dense layer with a much lower permeability, where the pitch of all layers is the same and the winding direction of all layers is the same, and has a very high permeability.

[0016] Advantageously, each strand of the inner layer and each strand of the outer layer are desaturated, which means that there is sufficient space between the wires of the outer layer for the elastomer compound to penetrate each strand.

[0017] Preferably, the strands do not undergo pre-forming.

[0018] The cord according to the invention as defined above is "bare" in the sense that it does not contain a polymer composition, and in particular the cord does not contain an elastomer composition.

[0019] The metal fine wire is understood to be a single metal fiber having a core mainly (i.e., 50% or more of its weight) or completely (100% of its weight) composed of a metal material, such as carbon steel. The metal fine wire can advantageously have a layer of metal coating covering the core, and the metal coating is selected from zinc, copper, tin, and alloys of these metals, such as brass, etc. Each fine wire is preferably made of pearlitic carbon steel or ferrite-pearlitic carbon steel.

[0020] The characteristic values described in this application regarding the bare cord are measured or determined from the cord as it is immediately after being manufactured, i.e., the cord before any step of embedding it in a polymer base material, especially an elastomer base material.

[0021] In this application, the range of values denoted by the expression "between a and b" represents the range of values greater than a and less than b (i.e., excluding the end points a and b), whereas the range of values denoted by the expression "from a to b" means the range of values from the end point "a" to the end point "b", i.e., including the exact end points "a" and "b".

[0022] Advantageously, As ≥ 1.5%, preferably As ≥ 2.0%.

[0023] Another main subject of the present invention is a cord extracted from a polymer base material, and this extracted cord is an inner layer of the cord composed of a multi-strand element with X = 1 having strands (T1) with K > 1 wound spirally around the main axis, and each strand has an inner layer composed of Q1 internal metal fine wires (plural possible), and an outer layer composed of Q3 external metal fine wires wound around the inner layer, and has an inner layer of the cord having at least two layers, and an outer layer of the cord composed of a multi-strand element with Y > 1 wound around the inner layer of the cord, and each multi-strand element has strands with L > 1 wound spirally around the axis, and each strand has an inner layer composed of Q1' internal metal fine wires (plural possible), An outer layer composed of Q3' external metal fine wires wound around an inner layer, and a cord outer layer having at least two layers including the same. Comprising The multi-strand element is spirally wound around the main axis. The cord has a structural elongation As' such that As' ≥ 0.3%, and the structural elongation As' is determined by applying ASTM standard D2969-04(2014) to the cord to obtain a force-elongation curve, and is equal to the elongation (unit: %) corresponding to the intersection of the tangent to the elastic part along a certain point on the elastic part of the force-elongation curve and the elongation axis of the force-elongation curve.

[0024] Preferably, the polymer base material is an elastomer base material.

[0025] The polymer base material, preferably the elastomer base material, is based on a polymer composition, preferably an elastomer composition.

[0026] It is understood that the polymer base material is a base material containing at least one polymer. Therefore, the polymer base material is based on a polymer composition.

[0027] What the elastomer base material means is a base material containing at least one elastomer. Therefore, a preferred elastomer base material is based on an elastomer composition.

[0028] The expression "based on ~" should be understood to mean that the composition comprises the compounds of the various components used and / or the products of in-situ reactions, and some of these components are at least partially capable of reacting with each other and / or are intended to react during the various stages of composition manufacture, and therefore the composition can be in a fully or partially crosslinked state or in an uncrosslinked state.

[0029] A polymer composition is understood to mean that the composition contains at least one polymer. Preferably, such a polymer can be a thermoplastic material, such as a polyester or a polyamide, a thermosetting polymer, an elastomer, such as natural rubber, a thermoplastic elastomer, or a combination of these polymers.

[0030] An elastomer composition is understood to mean that the composition contains at least one elastomer and at least one other component. Preferably, a composition containing at least one elastomer and at least one other component contains an elastomer, a crosslinking system, and a filler. Compositions that can be used for these plies are conventional compositions for skimming fibrous reinforcing elements and contain a diene elastomer, such as natural rubber, a reinforcing filler, such as carbon black and / or silica, a crosslinking system, such as a vulcanization system, preferably sulfur, stearic acid, and zinc oxide, and optionally a vulcanization accelerator and / or a retarder and / or various additives. The adhesion between the metal wire and the matrix in which they are embedded is provided, for example, by a metal coating, such as a brass layer.

[0031] The characteristic values described in this application for the extraction code are measured or determined on the code extracted from the polymer matrix, particularly the elastomer matrix, for example, with respect to a tire. Thus, for example, in the case of a tire, a piece of material located radially outside the code to be extracted is removed so that the code to be extracted can be seen at the same height radially as the polymer matrix. This removal can be done by peeling using a cutter and a gripper, or otherwise by planing. Next, the end of the code to be extracted is cut off using a knife. Next, the code is pulled out of the matrix while applying a relatively shallow angle so as not to plasticize the code to be extracted. Next, the extracted code is carefully cleaned, for example, using a knife, taking care not to damage the surface of the metal wire, so as to separate any remaining polymer matrix locally adhering to the code.

[0032] The advantageous features described below apply to both the code and the extraction code as defined above.

[0033] Preferably, the code has a code diameter such that the diameter D ranges from 3 mm to 9.5 mm, preferably from 4 mm to 7.5 mm. The diameter D is measured on the code in accordance with ASTM standard D2969-04.

[0034] By definition, the diameter of a strand is the diameter of the smallest circle that the strand can circumscribe on its inside.

[0035] By definition, the diameter of the code is the diameter of the smallest circle that the code without a trumpet can circumscribe on its inside.

[0036] Preferably, the diameter of the fine wires is, independently of each other, in the range from 0.15 mm to 0.50 mm, preferably from 0.18 mm to 0.35 mm, more preferably from 0.20 mm to 0.30 mm.

[0037] Preferably, all the fine wires in one and the same layer for a given strand all have substantially the same diameter. Advantageously, all the outer strands all have substantially the same diameter. What "substantially the same diameter" means is that the fine wires or strands have the same diameter within the range of industrial tolerances.

[0038] Advantageously, Y is equal to 6, 7, 8, 9 or 10, preferably Y = 6, 7 or 8, more preferably Y = 6.

[0039] Advantageously, K = 2, 3 or 4, preferably K = 3 or 4.

[0040] Advantageously, L = 2, 3 or 4, preferably L = 3 or 4.

[0041] In the first embodiment, each strand of the inner layer has two layers.

[0042] Advantageously, each strand of the outer layer has two layers.

[0043] Advantageously, in this first embodiment, in a preferred variant, each strand of the inner layer and the outer layer has two layers.

[0044] In the second embodiment, each strand of the inner layer has three layers, an intermediate layer composed of an intermediate metal wire Q2 wound around the inner layer, and an outer layer composed of an outer metal wire Q3 wound around the intermediate layer. It is provided with.

[0045] Advantageously, each strand of the outer layer has three layers, an intermediate layer composed of an intermediate metal wire Q2' wound around the inner layer, and an outer layer composed of an outer metal wire Q3' wound around the intermediate layer. It is provided with.

[0046] Advantageously, in this second embodiment, in a preferred variant, each strand of the inner layer and the outer layer has three layers.

[0047] Advantageously, each strand is of a type in which in-situ gumming is not performed. Not performing in-situ gumming means that before combining the strands with each other, each strand is composed of fine wires of various layers and does not show any polymer composition, especially any elastomer composition.

[0048] Strands of the internal multi-strand element of the cord according to the present invention

[0049] Advantageously, Q1 = 1, 2, 3 or 4, preferably Q1 = 1, 2 or 3, more preferably Q1 = 1 or 3.

[0050] Advantageously, Q3 = 5, 6, 7, 8, 9 or 10, preferably Q3 = 6, 7, 8 or 9, more preferably Q3 = 6 or 9.

[0051] In one embodiment, Q1 = 1.

[0052] Advantageously, Q3 = 5, 6 or 7, preferably Q3 = 6.

[0053] In another preferred embodiment, Q1 > 1, preferably Q1 = 2, 3 or 4.

[0054] Advantageously, Q3 = 7, 8, 9 or 10, preferably Q3 = 7, 8 or 9.

[0055] In the first variant, Q1 = 2, Q3 = 7 or 8, preferably Q1 = 2, Q3 = 7.

[0056] In the second variant, Q1 = 3, Q3 = 7, 8 or 9, preferably Q1 = 3, Q3 = 8.

[0057] In the third variant, Q1 = 4, Q3 = 7, 8, 9 or 10, preferably Q1 = 4, Q3 = 9.

[0058] Strands of the external multi-strand element of the cord according to the present invention

[0059] Advantageously, Q1' = 1, 2, 3 or 4, preferably Q1' = 1, 2 or 3, more preferably Q1' = 1 or 3.

[0060] Advantageously, Q3' = 5, 6, 7, 8, 9 or 10, preferably Q3' = 6, 7, 8 or 9, more preferably Q3' = 6 or 9.

[0061] In one embodiment, Q1' = 1.

[0062] Advantageously, Q3' = 5, 6 or 7, preferably Q3' = 6.

[0063] In another preferred embodiment, Q1' > 1, preferably Q1' = 2, 3 or 4.

[0064] Advantageously, Q3’ = 7, 8, 9 or 10, preferably Q3’ = 7, 8 or 9.

[0065] In a first variant, Q1’ = 2, Q3’ = 7 or 8, preferably Q1’ = 2, Q3’ = 7.

[0066] In a second variant, Q1’ = 3, Q3’ = 7, 8 or 9, preferably Q1’ = 3, Q3’ = 8.

[0067] In a third variant, Q1’ = 4, Q3’ = 7, 8, 9 or 10, preferably Q1’ = 4, Q3’ = 9.

[0068] Advantageously, Q1 = 1 and Q3 = 6, Q1’ = 1 and Q3’ = 6.

[0069] Reinforcement product according to the present invention

[0070] Another subject of the invention is a reinforcing product comprising a polymer matrix and at least one code or extraction code as defined above.

[0071] Advantageously, the reinforcing product comprises one or more codes according to the invention embedded in the polymer matrix and, in the case of a plurality of codes, the codes are arranged side by side in the main direction.

[0072] Tire according to the present invention

[0073] Another subject of the invention is a tire comprising at least one extraction code or reinforcing product as defined above.

[0074] A tire comprising an extraction code means a tire comprising a code whose characteristics, measured before extraction from the tire, are those of the extracted code, which code, before being incorporated into the tire, is a code such as those described above in this specification.

[0075] Preferably, the tire has a carcass reinforcement on which a crown reinforcement is radially mounted, the crown reinforcement being anchored to two beads and carrying on itself a tread, the crown reinforcement being joined to the beads by two sidewalls and comprising at least one cord as defined above.

[0076] In one preferred embodiment, the crown reinforcement comprises a protection reinforcement, a working reinforcement and an additional reinforcement comprising at least one cord as defined above, the additional reinforcement making an angle with the circumferential Z direction of the tire that is at most equal to 10°, preferably in the range from 0° to 5°, and being radially sandwiched between the working reinforcement and the carcass reinforcement.

[0077] The cords are intended in particular for industrial vehicles selected from large vehicles such as "large vehicles" (i.e., subways, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles), agricultural vehicles or plant construction vehicles, or other transport or handling vehicles.

[0078] Preferably, the tire is for a vehicle of the plant construction type. Thus, the tire has a size such that the diameter of the seat portion of the rim intended to receive the tire is 40 inches or more in inches.

[0079] The present invention also relates to an assembly according to the invention, or to a rubber article comprising the impregnated assembly according to the invention. What a rubber article means is any kind of article made of rubber, such as a ball, a non-pneumatic object such as a non-pneumatic tire casing, a conveyor belt or an endless track. A better understanding of the present invention should be obtained by reading the following examples, given merely as non-limiting examples and made with reference to the drawings.

Brief Description of the Drawings

[0080]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0081] Example of a tire according to the present invention

[0082] Reference systems X, Y, and Z corresponding to the normal axial direction (X), radial direction (Y), and circumferential direction (Z) of the tire are shown in FIGS. 1 and 2.

[0083] The "median circumferential surface" M of the tire is a plane perpendicular to the rotation axis of the tire and equidistant from the annular reinforcing structures of each bead.

[0084] FIGS. 1 and 2 represent a tire, generally designated by the reference numeral 10, according to the present invention.

[0085] The tire 10 is for large vehicles of the plant construction type, for example, the "dump truck" type. Accordingly, the tire 10 has dimensions of type 53 / 80R63.

[0086] The tire 10 has a crown 12 reinforced by a crown reinforcement 14, two sidewalls 16, and two beads 18, each of these beads 18 being reinforced using an annular structure, in this example a bead wire 20. The crown reinforcement 14 radially supports the tread 22 and is connected to the bead 18 by the sidewall 16. The carcass reinforcement 24 is firmly fixed by the two beads 18, in this example is wound around the two bead wires 20, and has a turn-up portion 26 positioned towards the outside of the tire 20, the turn-up portion 26 being shown here mounted on a wheel rim 28. The carcass reinforcement 24 radially supports the crown reinforcement 14.

[0087] The carcass reinforcement 24 comprises at least one carcass ply 30 reinforced by a radial carcass cord (not shown). The carcass cords are positioned substantially parallel to each other and form an angle between 80° and 90° with respect to the median circumferential plane M (a plane perpendicular to the axis of rotation of the tire, located in the middle between the two beads 18 and passing through the center of the crown reinforcement 14), extending from one bead 18 to the other.

[0088] The tire 10 also comprises a sealing ply 32 (commonly known as an "innerliner") made of elastomer, which defines the radially inner surface 34 of the tire 10 and is intended to protect the carcass ply 30 from the diffusion of air coming from the inner space of the tire 10.

[0089] The crown reinforcement 14 comprises, radially from the outside to the inside of the tire 10, a protection reinforcement 36 arranged radially inside the tread 22, a working reinforcement 38 arranged radially inside the protection reinforcement 36, and an additional reinforcement 40 arranged radially inside the working reinforcement 38. Thus, the protection reinforcement 36 is radially sandwiched between the tread 22 and the working reinforcement 38. The working reinforcement 38 is radially sandwiched between the protection reinforcement 36 and the additional reinforcement 40.

[0090] The protective reinforcement 36 comprises first and second protective plies 42, 44 provided with a protective metal cord, and the first ply 42 is arranged radially inside the second ply 44. Optionally, the protective metal cord forms an angle with the circumferential direction Z of the tire in a range equal to at least 10°, preferably from 10° to 35°, more preferably from 15° to 35°.

[0091] The working reinforcement 38 comprises first and second working plies 46, 48, and the first ply 46 is arranged radially inside the second ply 48.

[0092] An additional reinforcement 40, also called a limiter unit, one of whose functions is to partially absorb the mechanical stress load of inflation, comprises at least one cord 50 and forms an angle with the circumferential direction Z of the tire in a range equal to at most 10°, preferably from 5° to 10°.

[0093] Example of a reinforcement product according to the present invention

[0094] Figure 3 represents a reinforcement product, generally designated by reference numeral 100, according to the invention. The reinforcement product 100 comprises at least one cord 50, in this example a plurality of cords 50, embedded in a polymer matrix 102.

[0095] Figure 3 represents the polymer matrix 102, the cord 50 in a reference system X, Y, Z, where the direction Y is the radial direction and the directions X and Z are the axial and circumferential directions. In Figure 3, the reinforcement product 100 is arranged side by side in the main direction X and comprises a plurality of cords 50 that extend parallel to each other within the reinforcement product 100 and are embedded as a group in the polymer matrix 102. Here, the polymer matrix 102 is an elastomeric matrix based on an elastomeric composition.

[0096] Cord according to the first embodiment of the present invention

[0097] Figure 4 represents a cord 50 according to a first embodiment of the invention.

[0098] Referring to FIG. 5, each reinforcing element of the additional reinforcement is formed by an extraction code 50' described below after extraction from the tire 10. The code 50' is obtained by embedding it in the polymer base material that forms the polymer base material of each working ply in this example.

[0099] FIG. 7 shows a photograph of the code 50 in the polymer base material.

[0100] The code 50 and the extraction code 50' are made of metal and are of the multi-strand type with two multi-strand cylindrical layers. Therefore, it will be understood that the layer of strand elements in which the code 50 or 50' is made is two layers, neither more nor less.

[0101] At least 50%, preferably at least 60%, more preferably at least 70%, and most preferably, each metal wire of the code has a steel core with a composition compliant with NF-EN standard 10020 (September 2000) and a carbon content C > 0.80%, preferably C ≥ 0.82%. At least 50%, preferably at least 60%, more preferably at least 70%, and most preferably, each metal wire of the code has a steel core with a composition compliant with NF-EN standard 10020 (September 2000) and a carbon content C ≤ 1.20%, preferably C ≤ 1.10%. Here, each metal wire has a steel core with a composition compliant with NF-EN standard 10020 (September 2000) and a carbon content C = 0.86%.

[0102] Each wire has a breaking strength denoted as Rm such that 2500 ≤ Rm ≤ 3100 MPa. The steel for these wires is considered to be of the SHT ("super high tension") grade. Lower grade wires such as NT ("normal tension") or HT ("high tension") grades can be used in exactly the same way as other wires, for example, upper grade wires such as UT ("ultra high tension") or MT ("mega tension") grades.

[0103] Method for manufacturing a cord according to the present invention

[0104] Here, an example of a method for manufacturing the multi-strand code 50 will be described.

[0105] Each of the above-described internal strands T1 is manufactured according to a known method involving the following steps, preferably continuously performed inline: - First, a first assembly step of cabling or twisting six (N = 6) external fine wires F3 around the internal fine wire F1 of the internal layer C1 in the S direction with a pitch p3 to form the external layer C3 at a first assembly point, - Preferably, a final twist balancing step, is involved. Each of the above-described external strands T2 is manufactured according to a known method involving the following steps, preferably continuously performed inline: - First, a first assembly step of cabling or twisting six (N = 6) external fine wires F3' around the internal fine wire F1' of the internal layer C1' in the S direction with a pitch p3' to form the external layer C3' at a first assembly point, - Preferably, a final twist balancing step, is involved.

[0106] What "twist balancing" means is well known to those skilled in the art and is the elimination of the residual torque (or elastic recovery of the twist) applied to each fine wire of the strand in the outer layer.

[0107] After this final twist balancing step, the manufacture of the strand is completed. Each strand is wound onto one or more take-up reels for storage prior to subsequent operations of twisting and assembling the basic strands to obtain the multi-strand code.

[0108] To manufacture the multi-strand code of the present invention, the method is to twist the previously obtained strands using a stranding machine rated for strand assembly, as is well known to those skilled in the art.

[0109] In the step of manufacturing the multi-strand element M1 of the inner layer CI, the inner strands T1 with K = 3 are twisted and assembled in the S direction at the pitch P1 to form the multi-strand element M1 of the inner layer CI at the first assembly point.

[0110] In the step of manufacturing the multi-strand element M2 of the outer layer CE, the outer strands T2 with L = 3 are twisted together and assembled in the S direction at the pitch P2 to form the multi-strand element M2 of the outer layer CE at the first assembly point.

[0111] Next, in a later manufacturing process, the outer multi-strand elements M2 with Y = 6 are twisted together and assembled in the Z direction at the pitch pe to form an assembly of the layers CI and CE. Probably, in the last assembly step, the horn F is wound around the previously obtained assembly in the S direction at the pitch pf.

[0112] Then the cord 50 is incorporated by calendering into a composite blank formed from a known composition based on natural rubber and carbon black as a reinforcing filler, which has been conventionally used in the manufacture of the crown reinforcement of radial tires. This composition essentially contains, in addition to an elastomer and a reinforcing filler (carbon black), an antioxidant, stearic acid, extender oil, cobalt naphthenate as an adhesion promoter, and finally a vulcanization system (sulfur, accelerator, and ZnO).

[0113] The composite blank reinforced by these cords has an elastomer composition base material formed from two thin skim layers of an elastomer composition having a thickness in the range between 1 mm and 4 mm each, which are overlapped on both sides of the cord. The calendering pitch (the interval at which the cord is laid on the elastomer composition blank) is in the range from 4 mm to 8 mm.

[0114] Next, these composite blanks are used as the working ply in the crown reinforcement during the method of manufacturing a tire, and the method steps are known to those skilled in the art in another way.

[0115] Cord according to the second embodiment of the present invention

[0116] Figure 6 represents cord 60 according to the second embodiment of the present invention.

[0117] Unlike the first embodiment described above, the cord 60 according to the second embodiment is such that Q1 = Q1' = 3; Q2 = Q2' = 8; and Q3 = Q3' = 13.

[0118] Table 1 below summarizes the characteristics of various cords 50, 50' and 60.

[0119] To determine the breaking force of the cord, the cord is extracted, then the multi-strand elements M1 and M2 are extracted, and a tensile test is performed independently for each of the multi-strand elements. After summing the breaking forces for all the multi-strand elements, a correction factor of 90% is applied taking into account the performance degradation during assembly.

[0120] [Table 1]

[0121] Also, Table 2 below summarizes the characteristics of the prior art cord described in French Patent No. 2969181 (B).

[0122] [Table 2]

[0123] In order to obtain a cord having a good compromise between rigidity and flexibility, it has been found that the cords 50, 50' and 60 according to the present invention make it possible to obtain a cord having sufficient flexibility, sufficient metal mass, and sufficient breaking force compared to the prior art cords. The cord has sufficient flexibility to reduce the rigidity of the crown block, but has sufficient breaking force to withstand tensile stress loading.

[0124] The present invention is not limited to the above-described embodiments.

Explanation of Signs

[0125] 50 Code according to the first embodiment A Main shaft A’ Axis C1 Inner layer of the inner layer of the code C1’ Inner layer of the outer layer of the code C3 Outer layer of the inner layer of the code C3’ Outer layer of the outer layer of the code CE Outer layer of the code CI Inner layer of the code F1 Inner metal fine wire of the inner layer of the inner layer of the code F1’ Inner metal fine wire of the inner layer of the outer layer of the code F3 Outer metal fine wire of the outer layer of the inner layer of the code F3’ Outer metal fine wire of the outer layer of the outer layer of the code M1 Multi-strand element of the inner layer of the code M2 Multi-strand element of the outer layer of the code T1 Inner strand T2 Outer strand

Claims

1. A multistrand code (50) having two multistrand layers, wherein the code (50) is A code interior layer (CI) composed of a multi-strand element (M1) with X=1, having multiple strands (T1) with K>1 wound spirally around a main axis (A), wherein each strand (T1) is An internal layer (C1) composed of internal metal fine wires (multiple possible) (F1) of Q1, The outer layer (C3) is composed of an outer metal wire (F3) of Q3 wound around the inner layer (C1), The code interior layer (CI) has at least two layers (C1, C3) equipped with, The outer layer (CE) of the code is composed of a plurality of multi-strand elements (M2) with Y > 1 wound around the inner layer (CI) of the code, and each multi-strand element (M2) comprises a strand (T2) with L > 1 wound spirally around an axis (A'), and each strand (T2) is An inner layer (C1') composed of internal metal thin wires (multiple possible) (F1') of Q1', The outer layer (C3') is composed of an outer metal wire (F3') of Q3' wound around the inner layer (C1'), A code outer layer (CE) having at least two layers (C1', C3') equipped with, Equipped with, The multi-strand element (M2) is wound spirally around the main shaft (A), The code (50) has a structural elongation As such that As ≥ 1.0%, the structural elongation As is determined by applying ASTM standard D2969-04 (2014) to the code (50) to obtain a force-elongation curve, and the structural elongation As is equal to the elongation (in %) corresponding to the intersection point between the tangent to the elastic portion at a certain point along the elastic portion of the force-elongation curve and the elongation axis of the force-elongation curve.

2. Code (50) according to claim 1, wherein As ≥ 1.5%.

3. A multi-strand cord (50') having two multi-strand layers extracted from a polymer base material (102), wherein the extracted cord (50') is A code interior layer (CI) composed of a multi-strand element (M1) with X=1, each having strands (T1) of K>1 wound spirally around a main axis (A), wherein each strand (T1) is An internal layer (C1) composed of internal metal fine wires (multiple possible) (F1) of Q1, The outer layer (C3) is composed of an outer metal wire (F3) of Q3 wound around the inner layer (C1), A code interior layer (CI) having at least two layers (C1, C3) equipped with, The outer layer of the code (CE) is composed of multi-strand elements (M2) with Y > 1 wound around the inner layer of the code (CI), wherein each multi-strand element (M2) comprises strands (T2) with L > 1 wound spirally around an axis (A'), and each strand (T2) is An inner layer (C1') composed of internal metal thin wires (multiple possible) (F1') of Q1', The outer layer (C3') is composed of an outer metal wire (F3') of Q3' wound around the inner layer (C1'), A code outer layer (CE) having at least two layers (C1', C3') equipped with, Equipped with, The multi-strand element (M2) is wound spirally around the main shaft (A), The code (50') has a structural elongation As' such that As' ≥ 0.3%, the structural elongation As' is determined by applying ASTM standard D2969-04 (2014) to the code (50') to obtain a force-elongation curve, and the structural elongation As' is equal to the elongation (in %) corresponding to the intersection point between the tangent to the elastic portion at a certain point along the elastic portion of the force-elongation curve and the elongation axis of the force-elongation curve.

4. Each strand (T1) of the inner layer (CI) has two layers (C1, C3), the code (50, 50') according to claim 1 or 3.

5. Each strand (T2) of the outer layer (CE) has two layers (C1', C3'), the code (50, 50') according to claim 1 or 3.

6. Each strand (T1) of the aforementioned inner layer (CI) has three layers (C1, C2, C3), An intermediate layer (C2) is composed of an intermediate metal wire (F2) of Q2 wound around the inner layer (C1), The outer layer (C3) is composed of outer metal wires (F3) of Q3 wound around the intermediate layer (C2), A code (60) according to claim 1 or 3, comprising:

7. Each strand (T1) of the outer layer (CE) has three layers (C1', C2', C3'), An intermediate layer (C2') is composed of an intermediate metal wire (F2') of Q2' wound around the aforementioned inner layer (C1'), The outer layer (C3') is composed of an outer metal wire (F3') of Q3' wound around the intermediate layer (C2'), A code (60) according to claim 1 or 3, comprising:

8. Each strand (T1; T2) of the internal and external layers (CI; CE) has two layers (C1, C3, C1', C2'), the code (50, 50') according to claim 1 or 3.

9. A reinforced product (100) comprising an elastomer matrix (102) and at least one code (50') such that the properties measured after extraction are the properties of the extraction code (50') described in claim 3.

10. A tire (10) comprising at least one code (50') such that the characteristics of the code measured after extraction from the tire are the characteristics of the extracted code (50') described in claim 3, or the reinforcing product described in claim 9.

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