Cable extracted from a single layer with a uniform distribution of metallic wire elements

Abstract

The invention relates to a cable extracted (50) from a polymer matrix, the extracted cable (50) comprising a single layer (52) made up of N metallic wire elements (54) wound in a helical fashion, each metallic wire element (54) of the layer (52) describing, when the cable (50) extends in a substantially rectilinear direction, a helical trajectory around a principal axis (A) substantially parallel to the substantially rectilinear direction, with the space between 2 adjacent metallic wire elements being defined by: δ = (Dh-Df x sin(atan(cos(α) x tan(θ / 2)))) x sin(θ / 2) – Df x cos(atan(cos(α) x tan(θ / 2)))x cos(θ / 2) / cos(α), α being the helix angle, expressed in radians, of each metallic wire element (54) and θ being the angle expressed in radians between the minor axes of two successive ellipses representing two adjacent metallic wire elements (54) in the section of the cable (50).The ratio δmax / δref ranges from 1.0 to 2.9, where δref is the case where the space between the N metal wire elements is the same and δmax is the case where the space between 2 adjacent metal wire elements is greater than δref. Figure for abbreviation: Fig.5.

Description

Title of the invention: Cable extracted from a single layer with uniform distribution of metallic wire elements

[0001] The present invention relates to metal cables usable for reinforcing articles such as tires.

[0002] Although not limited to this type of application, the invention will be described more particularly with reference to a tire intended to equip vehicles carrying heavy loads, such as, for example, trucks, tractors, trailers or road buses.

[0003] By pneumatic tire, we mean a tire designed to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure greater than atmospheric pressure. A pneumatic tire according to the invention has a substantially toroidal shape.

[0004] Prior art knows of a tire comprising a top reinforcement comprising bi-module cables as described in application WO 2020021006. In order to obtain a reinforced product having sufficient rigidity, however, it is necessary to select the cable which has the expected rigidity once embedded in the polymer matrix.

[0005] Thus, it is necessary to select cables according to their intended use in the tire manufacturing process, particularly in the top layer, which requires high rigidity for tire support and sufficient elongation for the tire manufacturing / curing stage, and therefore a more or less pronounced bi-modulus behavior. This step can prove lengthy and tedious in order to select the reinforced product cable that meets the specifications.

[0006] Typically, to vary the stiffness of a reinforced product, those skilled in the art primarily modify the cable's architecture, for example by changing the helix angle. Evaluating several cable geometries is therefore necessary to vary the stiffness of the reinforced product in order to adapt it to its intended use.

[0007] The invention relates to a cable extracted from a polymer matrix, the extracted cable comprising a single layer made up of N metallic wire elements of diameter Df wound in a helical fashion, each metallic wire element of the layer describing, when the cable extends in a substantially straight direction, a helical trajectory of pitch P expressed in millimeters and helix angle a expressed in radians around a principal axis substantially parallel to the substantially straight direction, such that, in a cutting plane substantially perpendicular to the principal axis, the distance between the center of each wire element The metallic layer and the main axis are equal to half the helix diameter Dh and are substantially constant and equal for all metallic wire elements of the layer, the metallic wire elements defining an internal arch of the cable of diameter Dv, each metallic wire element having a helix radius of curvature Rf defined by Rf=P / (ir x Sin(2a)) in which, Dh, D, Dv, Df and Rf are expressed in millimeters: 9 <Rf / Df<30, et 1.30 < Dv / Df < 4.5; and the space between two adjacent metal wire elements is defined by ô = (Dh-Df x sin(atan(cos(a) x tan(0 / 2)))) x sin(0 / 2) - Df x cos(atan(cos(a) x tan(0 / 2))) x cos(0 / 2) / cos(a), where a is the helix angle, expressed in radians, of each metal wire element (54) and 0 is the angle, expressed in radians, between the minor axes of two successive ellipses representing two adjacent metal wire elements in the cable section; in which the ratio ô max / ô ref goes from 1.0 to 2.9 with ô ref being the case where the space between the N metallic wire elements is the same and ô max being the case where the space between 2 adjacent metallic wire elements is greater than ô ref.

[0008] Thanks to a relatively homogeneous distribution of the metallic wire elements, maximum cable stiffness is achieved. When there is an irregular distribution around the circumference of the cable, a loss of stiffness occurs because the reaction of the elastomeric matrix is ​​weaker when the distance between two adjacent metallic wire elements is reduced. This means that when manufacturing the cable, particular attention must be paid to the geometry and, more specifically, to the regularity of the distribution of the metallic wire elements along the circumference of the cable in order to obtain maximum cable stiffness.

[0009] A person skilled in the art has discovered that rigidity is ensured by the shearing of the elastomers, which tend to move out of the internal zone of the cable due to the reduction in internal volume. The increase in rigidity is therefore ensured by the shearing of the elastomeric matrix.

[0010] The dependence of the stiffness loss on irregularity depends on the ratio of the spacing distance θ between the metallic wire elements measured in the section. The variation in the spacing is compared to the initial regular reference. The closer the ratio θmax / θref is to 1, where θmax and θref are the maximum and regular values ​​of this distance, the more regular the cable distribution.

[0011] The values ​​of the characteristics Df, Dv and Rf, as well as the other characteristics described below, are measured on or determined from cables extracted from an elastomeric matrix, for example from a tire, and having then undergone a cleaning step during which all elastomeric matrix is ​​removed from the cable, in particular all material present inside the cable. To guarantee an original state, the adhesive interface between each metallic wire element and the elastomeric matrix must be removed, for example by an electrochemical process in a sodium carbonate bath. The effects associated with the shaping step of the tire manufacturing process described below, in particular cable elongation, are canceled out by the extraction of the ply and the cable, which, upon extraction, essentially regain their characteristics from before the shaping step.

[0012] The cable according to the invention comprises a single layer of helically wound metallic wire elements. In other words, the cable according to the invention comprises only one, not two, nor more than two layers of helically wound metallic wire elements. The layer consists of metallic wire elements, that is, several metallic wire elements, not a single metallic wire element. In one embodiment of the cable, for example, when the cable is produced as part of its manufacturing process, the cable according to the invention consists of the layer of wound metallic wire elements.

[0013] The cable according to the invention is a single-helix cable. By definition, a single-helix cable is a cable in which the axis of each wire element in the layer describes a single helix, as opposed to a double-helix cable in which the axis of each wire element describes a first helix around the cable axis and a second helix around a helix described by the cable axis. In other words, when the cable extends in a substantially straight direction, the cable comprises a single layer of wire elements wound together in a helix, each wire element in the layer describing a helical path around the substantially straight direction such that the distance between the center of each wire element in the layer and the axis of the substantially straight direction is substantially constant and equal for all wire elements in the layer.Conversely, when a double helix cable extends in a substantially straight direction, the distance between the center of each metallic wire element in the layer and the substantially straight direction is different for all metallic wire elements in the layer.

[0014] The cable according to the invention is devoid of a central metallic core. It is also referred to as an IxN structure cable, where N is the number of metallic wire elements, or as an open-cord cable. In the cable according to the invention defined above, the internal core is hollow and therefore devoid of any filling material, in particular, devoid of any elastomeric composition. It is thus referred to as a cable devoid of filling material.

[0015] The vault of the cable according to the invention is delimited by the metallic wire elements and corresponds to the volume delimited by a theoretical circle, on the one hand, radially inside each metallic wire element and, on the other hand, tangent to each metallic wire element.

[0016] By wire element, we mean an element extending longitudinally along a principal axis and having a cross-section perpendicular to the principal axis, the largest dimension G of which is relatively small compared to the dimension L along the principal axis. Relatively small means that L / G is greater than or equal to 100, preferably greater than or equal to 1000. This definition covers both wire elements with a circular cross-section and wire elements with a non-circular cross-section, for example, with a polygonal or oblong cross-section. Most preferably, each metallic wire element has a circular cross-section.

[0017] By metallic, we mean by definition a wire element consisting mainly (i.e., for more than 50% of its mass) or entirely (for 100% of its mass) of a metallic material. Each metallic wire element is preferably made of steel, more preferably of pearlitic or ferritic-pearlitic carbon steel, commonly referred to by those skilled in the art as carbon steel, or of stainless steel (by definition, steel containing at least 10.5% chromium).

[0018] θ represents the distance separating each pair of adjacent metallic wire elements, reduced to the length available for positioning the metallic wire elements on the layer. In the interval according to the invention, the ratio θmax / θref accounts for the loss of stiffness in the cable. The larger the ratio, the greater the decrease in stiffness.

[0019] The helix angle a is a quantity well known to those skilled in the art and can be determined by the formula a = atan(p*Dh / P)*180 / p with a in degrees, formula in which P is the pitch expressed in millimeters at which each metallic wire element is wound, Dh is the diameter of the helix in mm.

[0020] The helix diameter Dh corresponds to the diameter of the theoretical circle passing through the centers of the metallic wire elements of the layer in a plane perpendicular to the axis of the cable.

[0021] The arch diameter Dv, expressed in millimeters, is calculated according to the relation Dv=Dh-Df in which Df is the diameter of each metallic wire element and Dh the helix diameter, both expressed in millimeters.

[0022] The radius of curvature Rf, expressed in millimeters, is calculated according to the relation Rf=Dh / (2*sin2(a)), in which Dh is the diameter of the helix expressed in millimeters and a is the helix angle of each metallic wire element.

[0023] It is recalled that the pitch at which each metallic wire element is wound is the length traveled by this wire element, measured parallel to the axis of the cable in which it is located at, at the end of which the wire element having this pitch makes a complete turn around said axis of the cable.

[0024] If we take a section of the cable, the sections of the unit wire elements are essentially ellipses with minor axis Df and major axis Df / cos(a). The angle 0 between the minor axes of the two successive ellipses as shown in [Fig.4] between two adjacent wire elements in the section of the cable is defined by the following formula: 2.asin(Df / Dh) < 0 < 360 - 2xN*asin(Df / Dh).

[0025] The optional features described below may be combined with each other insofar as such combinations are technically compatible.

[0026] In an advantageous embodiment, all the metallic wire elements have the same diameter Df.

[0027] Advantageously, the ratio ô max / ô réf goes from 1.0 to 2.0 and preferably is equal to 1.0.

[0028] To calculate this ratio, a person skilled in the art will carry out 10 measurements on 10 sections The measurements will be taken over a given length, which may be approximately 2 meters. The distance between each pair of adjacent wire elements in a section is measured in a plane perpendicular to the helix axis. This distance is measured along a line perpendicular to the tangent to the outer diameter of the two nearest adjacent wire elements. For each measured section, a maximum distance (Δhmax) can be defined, which will be the maximum distance between each pair of adjacent wire elements. The value of Δhmax retained as a characteristic of the reinforcement will be the average of the ten Δhmax values ​​obtained for each section. Δhref is the value of the distance between adjacent wire elements when the distribution of the wire elements is regular.

[0029] The cable according to the invention is manufactured according to a process and using an installation described in documents WO2016083265 and WO2016083267. Such a process, which incorporates a slitting step, is distinct from a conventional cabling process comprising a single assembly step in which the metallic wire elements are wound helically, the assembly step being preceded by a preforming step of the metallic wire elements, notably to increase the structural elongation. Such processes and installations are described in documents EP0548539, EP1000194, EP0622489, and EP0143767. In these processes, to obtain the highest possible structural elongation, the metallic monofilaments are individually preformed.However, this individual pre-formation step of the metallic monofilaments, which requires a special installation, on the one hand, makes the process relatively unproductive compared to a process without a pre-formation step without allowing high structural elongations to be achieved and, on the other hand, alters the . Metallic monofilaments are thus pre-formed due to friction with the pre-forming tools. This alteration creates surface fracture initiation points on the metallic monofilaments and is therefore detrimental to their durability, particularly their compressive strength. The absence or presence of such pre-forming marks can be observed under an electron microscope after the manufacturing process, or more simply, by knowing the cable manufacturing process.

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

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

[0032] By polymer matrix, we mean a matrix comprising at least one polymer. The polymer matrix is ​​thus based on a polymer composition.

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

[0034] By the expression "based on", it is meant that the composition comprises the mixture and / or the in situ reaction product of the different constituents used, some of these constituents being able to react and / or being intended to react with each other, at least partially, during the different phases of manufacturing the composition; the composition can thus be in a totally or partially crosslinked state or in a non-crosslinked state.

[0035] By polymeric composition, it is understood that the composition comprises at least one polymer. Preferably, such a polymer may be a thermoplastic, for example a polyester or a polyamide, a thermosetting polymer, an elastomer, for example natural rubber, a thermoplastic elastomer or a mixture of these polymers.

[0036] By elastomeric composition, it is understood that the composition comprises at least one elastomer and at least one other component. Preferably, the composition comprising at least one elastomer and at least one other component includes an elastomer, a crosslinking system, and a filler. The compositions usable for these webs are conventional compositions for calendering reinforcing wire elements and comprise a diene elastomer, for example, natural rubber, a reinforcing filler, for example, carbon black and / or silica, a crosslinking system, for example, a vulcanization system, preferably comprising sulfur, stearic acid, and zinc oxide, and optionally a vulcanization accelerator and / or retarder and / or various additives. Adhesion between the metal wires and the matrix in which they are embedded is ensured, for example, by a metallic coating, for example, a layer of brass.

[0037] The values ​​of the characteristics described in this application for the extracted cable are measured on, or determined from, cables extracted from a polymer matrix, particularly an elastomeric one, for example, from a tire. Thus, for example, on a tire, the strip of material is removed radially on the outside of the cable to be extracted so as to expose the cable to be extracted radially flush with the polymer matrix. This removal can be done by peeling using pliers and knives or by planing. Then, the end of the cable to be extracted is freed using a knife. Then, the cable is pulled to extract it from the matrix at a relatively shallow angle so as not to plasticize the cable to be extracted.The extracted cables are then carefully cleaned, for example with a knife, so as to detach any remaining polymer matrix adhering locally to the cable, taking care not to damage the surface of the metal wires.

[0038] Advantageously, N goes from 4 to 15 and preferably from 4 to 10.

[0039] Advantageously, 11 < Rf / Df < 19.

[0040] Advantageously, 1.30 < Dv / Df < 3.50, preferably 1.30 < Dv / Df < 3.00.

[0041] Preferably, the helix radius of curvature Rf is such that 2 mm < Rf < 7 mm, of Preference 2 mm < Rf < 5 mm and more preferably 3 mm < Rf < 5 mm.

[0042] In an embodiment of a cable intended for the reinforcement of a tire for industrial vehicles chosen from vans, "Heavy goods vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), we have 4 mm < Rf < 6 mm and preferably 4 mm < Rf < 5 mm.

[0043] Advantageously, the helix diameter Dh of each wire element (54) is such that 0.40 mm < Dh < 2.00 mm, preferably 0.50 mm < Dh < 1.80 mm.

[0044] In an embodiment of a cable intended for the reinforcement of a tire for industrial vehicles chosen from vans, "Heavy goods vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), we have 0.85 mm < Dh < 1.20 mm and preferably 0.90 mm < Dh <1.15 mm.

[0045] Preferably, Df is such that 0.10 mm < Df < 0.50 mm, preferably 0.25 mm < Df < 0.45 mm and more preferably 0.25 mm < Df < 0.40 mm.

[0046] In an embodiment of a cable intended for the reinforcement of a tire for industrial vehicles chosen from vans, "Heavy goods vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), we have 0.22 mm < Df < 0.40 mm and preferably 0.25 mm < Df < 0.38 mm.

[0047] Advantageously, Dv is such that Dv > 0.46 mm, preferably 0.46 mm < Dv < 1.50 mm.

[0048] In an embodiment of a cable intended for reinforcing a tire for industrial vehicles selected from vans, "Heavy Goods Vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), we have 0.50 mm < Dv < 0.80 mm.

[0049] Advantageously, each metallic wire element (54) is wound at a pitch P such that 3 mm < P < 15 mm, preferably 3 mm < P < 13 mm.

[0050] In an embodiment of a cable intended for the reinforcement of a tire for industrial vehicles chosen from vans, "Heavy goods vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), we have 7 mm < P < 15 mm.

[0051] Advantageously, the diameter D of the cable is such that D < 2.50 mm, preferably 0.75 mm < D < 2.40 mm and more preferably 1.00 mm < D < 2.00 mm.

[0052] The diameter or apparent diameter, denoted D, is measured using a thickness gauge whose probe diameter is at least 1.5 times the pitch P of the wire winding (for example, the KAEFER JD50 model, which achieves an accuracy of 1 / 100 of a millimeter, is equipped with type a probes, and has a contact pressure close to 0.6 N). The measurement protocol consists of three repetitions of a series of three measurements (carried out perpendicular to the cable axis and under zero tension), the second and third of which are taken in a direction angularly offset from the previous one by one-third of a turn, by rotating the measurement direction around the cable axis.

[0053] In an embodiment of a cable intended for the reinforcement of a tire for industrial vehicles chosen from vans, "Heavy goods vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), we have 1.15 mm < D < 1.55 mm.

[0054] In one embodiment, each metal wire element comprises a single metal monofilament. Advantageously, each metal wire element consists of a metal monofilament. In a variant of this embodiment, the metal monofilament is directly coated with a layer of metallic coating comprising copper, zinc, tin, cobalt, or an alloy of these metals, for example, brass or bronze. In this variant, each metal wire element then consists of the metal monofilament, for example, steel, forming a core, directly coated with the metallic coating layer.

[0055] In this embodiment, each elementary metallic monofilament is, as described above, preferably made of steel, and has a mechanical strength ranging from 1000 MPa to 5000 MPa. Such mechanical strengths correspond to the steel grades commonly encountered in the field of pneumatics, namely, NT (Normal Tensile), HT (High Tensile), ST (Super Tensile), SHT (Super High Tensile), UT (Ultra Tensile), UHT (Ultra High Tensile), and MT (Mega) grades. Tensile), the use of high mechanical strengths allowing possibly improved reinforcement of the matrix in which the cable is intended to be embedded and a lightening of the matrix thus reinforced.

[0056] Advantageously, the ratio K of the pitch P to the diameter Df of each metallic wire element (54), P and Df being expressed in millimeters, is such that 19 < K < 44.

[0057] Advantageously, the helix angle a of each metallic wire element (54) is such that 13° < a < 30°.

[0058] Advantageously, each metallic wire element is free of pre-forming marks. In other words, the cable is obtained by a process without individual pre-forming steps for each of the metallic wire elements.

[0059] As described above, the cable according to the invention is manufactured according to a process and using an installation described in documents WO2016083265 and WO2016083267. This process includes a step of assembling M metallic wire elements together in a layer of M metallic wire elements around a transient core to form a transient assembly, and a step of splitting the transient assembly into at least first and second assemblies of M1 metallic wire elements and M2 metallic wire elements. At least one of the first and second assemblies then forms the cable according to the invention, i.e., M1=N and / or M2=N.

[0060] Advantageously, in a first embodiment, the step of splitting the transient assembly includes a step of separating the transient core from the first and second assemblies. In this embodiment, the first assembly consists of M1 metallic wire elements wound together and distributed in a single layer around the axis of the first assembly. Similarly, the second assembly in this embodiment consists of M2 metallic wire elements wound together and distributed in a single layer around the axis of the second assembly. In other words, in this first embodiment, since the transient core comprises at least one wire element, each wire element of the transient core does not belong to the first and second assemblies of M1 metallic wire elements and M2 metallic wire elements. Thus, M1 + M2 = M.

[0061] In a first preferred embodiment of this first embodiment, during the splitting step, the first assembly is separated from a transient set formed by the second assembly and the transient core, and then the second assembly and the transient core are separated from each other. In a second embodiment, during the splitting step, the transient core, the first assembly, and the second assembly are simultaneously separated from each other in pairs.

[0062] Advantageously, the process includes a transient core recycling step during which: - we recover the transient kernel downstream of the splitting step, and - we introduce the transient kernel retrieved previously upstream of the step assembly.

[0063] In a preferred embodiment, the transient nucleus recycling step can be continuous, that is, the transient nucleus exiting the separation step is reintroduced into the assembly step without an intermediate storage step for the transient nucleus. In another embodiment, the transient nucleus recycling step is discontinuous, that is, with an intermediate storage step for the transient nucleus.

[0064] More preferably, a textile transitional core is used.

[0065] In a second embodiment, the transient assembly splitting step includes a step of splitting the transient core between at least the first and second assemblies. Thus, in this second embodiment, two assemblies of metallic wire elements are obtained, each comprising a layer of P1 and P2 metallic wire elements wound together in a helix, respectively, and for at least one of the assemblies, a central core comprising or consisting of at least a portion of the transient core around which the metallic wire elements of the layer are wound. In other words, in this second embodiment, the transient core comprising K metallic wire element(s), at least one of the K metallic wire element(s) of the transient core belongs to at least one of the first and second assemblies of M1 metallic wire elements and M2 metallic wire elements.

[0066] Advantageously, during the splitting step, at least a first part of the transient core is split with first metallic wire elements of the transient assembly so as to form the first assembly.

[0067] Thus, the first assembly comprises a layer of PI metallic wire elements wound together in a helix and a central core comprising or consisting of a first part (Kl wire element(s)) of the K metallic wire elements of the transient core and around which the PI metallic wire elements are wound together in a helix. We have P1+K1=M1.

[0068] Advantageously, during the splitting step, at least a second part of the transient core is split with second metallic wire elements of the transient assembly so as to form the second assembly.

[0069] Thus, the second assembly comprises a layer of P2 metallic wire elements wound together in a helix and a central core comprising or constituted by a second part (K2 wire element(s)) of the K wire elements of the transient core and around which the P2 metallic wire elements are wound together in a helix. We have P2+K2=M2.

[0070] Preferably, the first and second assemblies are formed simultaneously.

[0071] Preferably, before the splitting step, the first and second parts of the transient kernel constitute the transient kernel. Thus, the first and second parts of the transient kernel are complementary. Therefore, K1 + K2 = K. In a variant, we could have K1 + K2 <k.

[0072] In one variant, the first assembly comprises a layer of PI metallic wire elements wound together in a helix around a central core comprising or constituted by the transient core and the second assembly comprises a layer of P2=M2 metallic wire elements wound together in a helix and lacking a central core.

[0073] In one embodiment, the assembly step is performed by twisting. In such a case, the metal wire elements undergo both collective and individual twisting about their own axis, which generates a detorsion torque on each of the metal wire elements. In another embodiment, the assembly step is performed by wiring. In this case, the metal wire elements do not undergo twisting about their own axis, due to synchronous rotation before and after the assembly point.

[0074] Preferably, in the case of a twisting assembly step, the process includes a balancing step of the transient assembly. Thus, since the balancing step is performed on the assembly consisting of the M metallic wire elements and the transient core, the balancing step is implicitly performed upstream of the splitting step.

[0075] Advantageously, the process includes a balancing step of at least one of the first and second assemblies after the splitting step.

[0076] Advantageously, the method includes a step of maintaining the rotation of the first and second assemblies around their respective direction of travel. This step is performed after the splitting step and before the balancing step of at least one of the first and second assemblies.

[0077] REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0078] The invention also relates to a reinforced product comprising a polymer matrix and at least one extracted cable as defined above.

[0079] Advantageously, the reinforced product comprises one or more cables according to the invention embedded in the polymer matrix, and in the case of several cables, the cables are arranged side by side along a main direction.

[0080] PNEUMATIC ACCORDING TO THE INVENTION

[0081] The invention also relates to a tire comprising at least one extracted cable as defined above or a reinforced product as defined above.

[0082] Preferably, the tire comprises a crown including a tread and a crown reinforcement, two sidewalls, two beads, each sidewall connecting each bead to the crown, the crown reinforcement extending into the crown in a circumferential direction of the tire, the tire comprising a carcass reinforcement anchored in each of the beads and extending into the sidewalls and into the crown, the crown reinforcement being radially intercalated between the carcass reinforcement and the tread, the crown reinforcement comprising at least one reinforced product as defined above.

[0083] Preferably, the top reinforcement comprises a shrink-fit reinforcement including at least one shrink-fit layer and preferably a single shrink-fit layer. The shrink-fit reinforcement is preferably constituted by a shrink-fit layer. This embodiment is particularly suitable for a tire and is especially intended for industrial vehicles selected from heavy vehicles such as "heavy goods vehicles" - i.e., subways, buses, road transport vehicles (trucks, tractors, trailers), off-road vehicles - agricultural or construction equipment, other transport or handling vehicles.

[0084] Preferably, the top reinforcement includes a working reinforcement comprising at least one working layer.

[0085] In heavy-duty applications for load transport, the shrink-fitting reinforcement usually comprises a shrink-fitting sheet made by the circumferential winding of a shrink-fitting wire or a continuous shrink-fitting strip, forming angles of no more than 5° with the circumferential direction.

[0086] In one embodiment, the shrink-fit armature is radially intercalated between the two working armatures.

[0087] Advantageously, the shrink-fitting layer comprises at least one reinforced product as defined above.

[0088] Preferably, the tire is for heavy-duty vehicles. Thus, the tire has a dimension in which the diameter, in inches, of the seat of the rim on which the tire is intended to be mounted is greater than or equal to 20 inches.

[0089] The invention will be better understood upon reading the following examples, given solely by way of non-limiting examples and made with reference to the drawings in which: - [Fig.1] is a cross-sectional view perpendicular to the circumferential direction of a tire according to the invention; - [Fig.2] is a detailed view of area II of [Fig.1]; - [Fig.3] is a cross-sectional view of a reinforced product (R) according to the invention; - [Fig. 4] is a schematic cross-sectional view perpendicular to the axis of a cable for determining the distance between two adjacent metallic wire elements and the angle θ; - [Fig. 5] is a schematic cross-sectional view perpendicular to the axis of the cable (assumed to be straight and at rest) of a cable (50) according to the invention; and - the [Fig.6] a schematic cross-sectional view perpendicular to the axis of the cable (assumed to be straight and at rest) of a comparative cable Cl.

[0090] EXAMPLE OF A PNEUMATIC ACCORDING TO THE INVENTION

[0091] In figures 1 and 2, a reference frame X, Y, Z corresponding to the usual axial (X), radial (Y) and circumferential (Z) orientations of a tire is shown.

[0092] The "circumferential median plane" M of the tire is the plane which is normal to the axis of rotation of the tire and which is located equidistant from the annular reinforcement structures of each bead.

[0093] Figures 1 and 2 show a tire according to the invention and designated by the general reference P.

[0094] The P tire is for heavy vehicles of the heavy goods vehicle type. Thus, the P tire has a size of type 315 / 70 R 22.5.

[0095] The tire P comprises a crown 12 reinforced by a crown reinforcement 14, two sidewalls 16, and two bead 18, each of these 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 and includes a turret 26 disposed towards the outside of the tire 20, which is here shown mounted on a rim 28. The carcass reinforcement 24 is radially surmounted by the crown reinforcement 14.

[0096] The carcass reinforcement 24 comprises at least one carcass layer 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).

[0097] The tire P also includes a sealing layer made of an elastomer (commonly called inner rubber) which defines the radially internal face of the tire P and which is intended to protect the carcass layer from the diffusion of air from the space inside the tire P.

[0098] The apex reinforcement 14 comprises, radially from the outside to the inside of the tire P, a working reinforcement arranged radially inside the tread 22.

[0099] The working frame comprises first and second working layers, the first layer formed of metal cables oriented at an angle of 20°; a shrink-fit frame comprising a single shrink-fit layer comprising a reinforced product as described below and a second working layer formed of metal cables oriented at an angle of 44°, crossed with the metal cables of the first working layer, the cables of each of the working layers being oriented on either side of the circumferential direction.

[0100] The top reinforcement 14 is surmounted by the tread 20.

[0101] EXAMPLE OF A REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0102] Figure 3 shows a reinforced product according to the invention and designated by the general reference R. The reinforced product R comprises at least one cable 50, in this case several cables 50, embedded in the polymeric matrix Ma.

[0103] In [Fig.3], the polymer matrix Ma is shown, the cables 50 in a 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. In [Fig.3], the reinforced product R comprises several cables 50 arranged side by side along the principal direction X and extending parallel to each other within the reinforced product R and collectively embedded in the polymer matrix Ma.

[0104] Here, the polymeric matrix Ma is an elastomeric matrix based on an elastomeric composition.

[0105] CABLE ACCORDING TO ONE EMBODIMENT OF THE INVENTION

[0106] The extracted cable 50 according to the embodiment of the invention is shown in [Fig.5] and the comparative cable Cl having the same characteristics as the cable 50 except the ô max is shown in [Fig.6].

[0107] Each protective reinforcement element and each reinforcing element, 55, is formed, after extraction from the tire 10, by an extracted cable 50 as described below. The cable 50 is obtained by embedding it in a polymer matrix, in this case in a polymer matrix forming respectively each polymer matrix of each protective layer 42, 44 and each reinforcing layer 52, 54 in which the protective reinforcement and reinforcing elements are respectively embedded.

[0108] The extracted cable 50 is a single-layer metallic cable.

[0109] The cable 50 comprises a structural layer IxN comprising a single layer 52 of N = 5 metallic wire elements 54 wound helically around a main axis A extending substantially parallel to the direction in which the cable extends along its greatest length.

[0110] In the illustrated embodiment, each metal wire element 54 comprises a single metal monofilament. Each metal wire element 54 also comprises a layer (not shown) of a metallic coating comprising Copper, zinc, tin, cobalt, or an alloy of these metals, in this case brass. Each metal monofilament is made of carbon steel and has a mechanical resistance of 3100 MPa. [YES] [Table 1] Cable Cl 50 60 N / cable direction 5 / S 5 / S 5 / S Df(mm) 0.26 0.26 0.40 Dh (mm) 0.67 0.64 1.03 D (mm) 0.93 0.90 1.43 a(°) 9.95 15.96 13.98 0(°) 72 72 72 ô ref (mm) 0.13 0.11 0.20 ô max (mm) 0.39 0.11 0.20 As (%) 0.15 0.39 0.33 Dv (mm) 0.41 0.38 0.63 Rf (mm) 11.2 4.2 8.8 P (mm) 12 7 13 Dv / Df 1.58 1.45 1.58 Rf / Df 43.2 16.2 22.1 ô max / ô ref 3.0 1.0 1.0 % loss of rigidity 30 0 0

[0112] Thus, the cables according to the invention make it possible to solve the problems mentioned in the preamble. Thanks to a relatively homogeneous distribution of the metallic wire elements for cables 50 and 60, maximum cable rigidity is obtained with no loss of rigidity. When there is an irregular distribution around the circumference of the cable, as with cable Cl, a 30% loss of rigidity is observed.

[0113] The invention is not limited to the embodiments described above

Claims

1.

2. Demands Cable extracted (50) from a polymer matrix, the extracted cable (50) comprising a single layer (52) made up of N metallic wire elements (54) of diameter Df wound in a helix, each metallic wire element (54) of the layer (52) describing, when the cable (50) extends in a substantially rectilinear direction, a helical trajectory of pitch P expressed in millimeters and helix angle a expressed in radians, around a principal axis (A) substantially parallel to the substantially rectilinear direction, such that, in a cutting plane substantially perpendicular to the principal axis (A), the distance between the center of each metallic wire element (54) of the layer (52) and the principal axis (A) is equal to half the helix diameter Dh and is substantially constant and equal for all the metallic wire elements (54) of the layer (52), the metallic wire elements (54) defining an internal arch (58) of the cable of diameter Dv with Dv=Dh-Df,each metallic wire element (54) having a helical radius of curvature Rf defined by Rf=P / (ir x Sin(2a)) in which, Dh, D, Dv, Df and Rf are expressed in millimeters: 9 <Rf / Df<30, et 1,30 <Dv / Df< 4.5 ; et l’espace entre 2 éléments filaires métalliques adjacents est défini par ô = (Dh-Df x sin(atan(cos(a) x tan(0 / 2)))) x sin(0 / 2) - Df x cos(atan(cos(a) x tan(0 / 2)))x cos(0 / 2) / cos(a ), 0 étant l’angle exprimé en radian entre les petits axes de deux ellipses successives représentant deux éléments filaires métalliques (54) adjacents dans la section du câble (50) tel que 2.asin(Df / Dh) < 0 < 360 - 2xN*asin(Df / Dh);, characterized in that: the ratio ô max / ô réf ranges from 1.0 to 2.9, with ô réf being the case where the space between the N metallic wire elements is the same and ô max being the case where the space between 2 adjacent metallic wire elements is greater than ô réf; and in which N ranges from 4 to 15. Extracted cable (50) according to the preceding claim, wherein the ratio ômax / ôref goes from 1.0 to 2.0 and preferably is equal to 1.

0.

3. Extracted cable (50) according to any one of the preceding claims, in which N ranges from 4 to 10.

4. Extracted cable (50) according to any one of the preceding claims, wherein 11 < Rf / Df < 19.

5. Extracted cable (50) according to any one of the preceding claims, wherein 1.30 < Dv / Df < 3.50, preferably 1.30 < Dv / Df < 3.

00.

6. Extracted cable (50) according to any one of the preceding claims, wherein the helix bend radius Rf is such that 2 mm < Rf < 7 mm, preferably 2 mm < Rf < 5 mm and more preferably 3 mm < Rf < 5 mm.

7. Extracted cable (50) according to any one of the preceding claims, wherein the helix diameter Dh of each metallic wire element (54) is such that 0.40 mm < Dh < 2.00 mm, preferably 0.50 mm < Dh < 1.80 mm.

8. Extracted cable (50) according to any one of the preceding claims, wherein Df is such that 0.10 mm < Df < 0.50 mm, preferably 0.25 mm < Df < 0.45 mm and more preferably 0.25 mm < Df < 0.40 mm.

9. Extracted cable (50) according to any one of the preceding claims, wherein Dv is such that Dv > 0.46 mm, preferably 0.46 mm < Dv < 1.50 mm.

10. Extracted cable (50) according to any one of the preceding claims, wherein each metallic wire element (54) is wound at a pitch P such that 3 mm < P < 15 mm, preferably 3 mm < P < 13 mm.

11. Extracted cable (50) according to any one of the preceding claims, having a diameter D such that D < 2.50 mm, preferably 0.75 mm < D < 2.40 mm and more preferably 1.00 mm < D < 2.00 mm.

12. Extracted cable (50) according to any one of the preceding claims, wherein the ratio K of the pitch P to the diameter Df of each metallic wire element (54), P and Df being expressed in millimeters, is such that 19 < K < 44.

13. Extracted cable (50) according to any one of the preceding claims, wherein the helix angle a of each metallic wire element (54) is such that 13° < a < 30°.

14. Reinforced product (R), characterized in that it comprises a polymer matrix (Ma) and at least one extracted cable (50) according to any one of claims 1 to 13.

15. Pneumatic (P), characterized in that it comprises at least one extracted cable (50) according to any one of claims 1 to 13 or a reinforced product according to claim 14.

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