Cable extracted from a layer with uniform distribution of metal wire elements

Abstract

The invention relates to a cable (50) extracted from a polymer matrix, the extracted cable (50) comprising a single layer (52) consisting of N helically wound metal wire elements (54), each metal wire element (54) of the layer (52) describing, when the cable (50) extends in a substantially rectilinear direction, a helical path about a main axis (A) substantially parallel to the substantially rectilinear direction, with the space between two adjacent metal wire elements being defined by: delta = (Dh-Df × sin(arctan(cos(alpha) × tan(theta / 2)))) × sin(theta / 2) – Df × cos(arctan(cos(alpha) × tan(theta / 2))) × cos(theta / 2) / cos(alpha), alpha being the helical angle, expressed in radians, of each metal wire element (54) and theta being the angle expressed in radians between the minor axes of two successive ellipses representing two adjacent metal wire elements (54) in the section of the cable (50), the delta max:delta ref ratio ranging from 1.0 to 2.9, with delta ref being the case in which the space between the N metal wire elements is the same and delta max being the case in which the space between two adjacent metal wire elements is greater than delta ref; and wherein N ranges from 4 to 15.

Description

Cable extracted from a 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 more particularly described with reference to a tire intended to equip vehicles carrying heavy loads, such as, for example, trucks, tractors, trailers or road buses.

[0003] By tire is meant a bandage intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire according to the invention has a structure of substantially toroidal shape.

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

[0005] Thus, it is necessary to proceed with cable selections according to the position for which it is intended in the tire and in particular in the crown ply which requires high rigidity for the tire holding and sufficient elongation for the tire manufacturing / curing stage and therefore a more or less marked bi-module behavior. This stage can prove to be long and tedious to select the cable of the reinforced product meeting the specifications.

[0006] Usually, to vary the stiffness of a reinforced product, the person skilled in the art mainly plays on the architecture of the cable, for example by modifying the helix angle. The evaluation of several cable geometries is therefore necessary to vary the stiffness of the reinforced product in order to adapt the reinforced product to the intended use.

[0007] The invention relates to a cable extracted from a polymer matrix, the extracted cable comprising a single layer consisting of N metallic wire elements of diameter Df wound in a helix, each metallic wire element of the layer describing, when the cable extends in a substantially rectilinear direction, a helix-shaped trajectory of pitch P expressed in millimeters and helix angle a expressed in radians around a main axis substantially parallel to the substantially rectilinear direction, such that, in a section plane substantially perpendicular to the main axis, the distance between the center of each metallic wire element of the layer and the main axis is equal to half the helix diameter Dh and is substantially constant and equal for all the 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 curvature radius Rf, defined by Rf=P / (TT x Sin(2a)) in which , Dh, D, Dv, Df and Rf are expressed in millimeters: 9 < Rf / Df < 30, and 1.30 < Dv / Df < 4.5; and the space between 2 adjacent metal wire elements is defined by 5 = (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), a being the helix angle, expressed in radians, of each metal wire element (54) and 0 being the angle expressed in radians between the minor axes of two successive ellipses representing two adjacent metal wire elements in the section of the cable; in which the ratio 5 ma x / 5 ref ranges from 1.0 to 2.9 with 5 ref being the case where the space between the N metal wire elements is the same and 5 max being the case where the space between 2 adjacent metal wire elements is greater than 5 ref.

[0008] A relatively uniform distribution of the metal wire elements results in maximum cable stiffness. When there is an uneven distribution around the circumference of the cable, there is a loss of stiffness because the reaction of the elastomeric matrix is ​​less strong when the distance between two adjacent metal wire elements is reduced. This means that when the cable is manufactured, special attention must be paid to the geometry and more specifically to the regularity of the distribution of the metal wire elements along the circumference of the cable in order to achieve maximum cable stiffness.

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

[0010] The dependence of the loss of stiffness on the irregularity depends on the ratio of the spacing distance 5 between the measured metallic wire elements in the section. The variation of the gap is compared with the initial regular reference. The higher the ratio 5 ma x / 5 ref is close to 1 where 5 ma x and 5 ré f are the maximum and regular values ​​of this distance, the more the cable has a regular 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 the cables extracted from an elastomeric matrix, for example from a tire, and having then undergone a cleaning step during which any elastomeric matrix, in particular any material present inside the cable, is removed from the cable. To guarantee an original condition, 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 above below, in particular the elongation of the cables, are cancelled by the extraction of the sheet and the cable which, during extraction, substantially regain their characteristics from before the shaping stage.

[0012] The cable according to the invention comprises a single layer of helically wound metal wire elements. In other words, the cable according to the invention comprises only one, not two, nor more than two layers of helically wound metal wire elements. The layer is made up of metal wire elements, i.e. several metal wire elements, not a single metal wire element. In one embodiment of the cable, for example when the cable is derived from its manufacturing process, the cable according to the invention is made up of the layer of wound metal wire elements.

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

[0014] The cable according to the invention is devoid of a central metal core. This is also referred to as a 1xN structure cable in which N is the number of metal wire elements or even an open-cord cable. In the cable according to the invention defined above, the internal arch is empty and therefore devoid of any filling material, in particular devoid of any elastomeric composition. This is then referred to as a cable devoid of filling material.

[0015] The arch 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 interior to each metallic wire element and, on the other hand, tangent to each metallic wire element.

[0016] By wire element is meant an element extending longitudinally along a main axis and having a section perpendicular to the main axis whose largest dimension G is relatively small compared to the dimension L along the main axis. By relatively small is meant that L / G is greater than or equal to 100, preferably greater than or equal to 1000. This definition covers both wire elements of circular section and wire elements of non-circular section, for example of polygonal or oblong section. Very preferably, each metal wire element has a circular section.

[0017] By definition, metallic means 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 ferrito-pearlitic carbon steel, commonly called carbon steel by those skilled in the art, or even stainless steel (by definition, steel containing at least 10.5% chromium).

[0018] 5 is representative of the distance separating each pair of adjacent metal wire elements reduced to the length available for positioning the metal wire elements on the layer. In the interval according to the invention, the ratio 5 ma x / 5 ref accounts for the loss of cable stiffness. The higher the ratio, the greater the drop 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(7t*Dh / P)*180 / 7t with a in degrees, formula in which P is the pitch expressed in millimeters at which each metal 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 relationship Dv=Dh- Df in which Df is the diameter of each 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*sin 2(a)), where Dh is the helix diameter expressed in millimeters and a is the helix angle of each wire element.

[0023] It is recalled that the pitch at which each metallic wire element is wound is the length travelled by this wire element, measured parallel to the axis of the cable in which it is located, 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 unitary wire elements are substantially ellipses with minor axis Df and major axis Df / cos(a). The angle 0 between the minor axes of the two successive ellipses as represented in figure 4 between two adjacent wire elements in the section of the cable and is defined by the following formula: 2.asin(Df / Dh) < 0 < 360 - 2xN*asin(Df / Dh).

[0025] The optional features described below can be combined with each other. with others to the extent that such combinations are technically compatible.

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

[0027] Advantageously, the report 5 ma x / 5 ref ranges from 1.0 to 2.0 and preferably is equal to 1.0.

[0028] To calculate this ratio, the person skilled in the art will take 10 measurements on 10 different sections distributed over a given length which may be approximately 2 meters. He will measure the distance between each pair of adjacent metal wire elements in a section which is taken in a plane perpendicular to the axis of the helix. This distance is measured on a line perpendicular to the tangent to the external diameter of two closest adjacent wire elements. For each measured section, a 5 max can be defined which will be the maximum of the distances between each pair of adjacent wire elements. The value of 5 max retained as a characteristic of the reinforcement will be the average of the 5 max of the ten values ​​of 5 max obtained for each section. 5 ref is the value of the distance between the adjacent wire elements when the distribution of the wire elements is regular.

[0029] The cable according to the invention is manufactured in accordance with a method and by implementing an installation described in documents WO2016083265 and WO2016083267. Such a method implementing a fractionation step is to be distinguished from a conventional cabling method comprising a single assembly step in which the metal wire elements are wound in a helix, the assembly step being preceded by a step of preforming the metal wire elements in order in particular to increase the value of the structural elongation. Such methods and installations are described in documents EP0548539, EP1000194, EP0622489 or EP0143767. During these methods, in order to obtain the highest possible structural elongation, the metal monofilaments are individually preformed.However, this step of individual preforming of the metal monofilaments, which requires a special installation, on the one hand, makes the process relatively unproductive compared to a process without a preforming step without however allowing high structural elongations to be achieved and, on the other hand, alters the metal monofilaments thus preformed due to friction with the preforming tools. Such an alteration creates incipient breaks on the surface of the metal monofilaments and is therefore detrimental to the endurance of the metal monofilaments, in particular to their endurance in compression. The absence or presence of such preforming marks can be observed under an electron microscope at the end of the manufacturing process, or more simply, by knowing the manufacturing process of the cable.

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

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

[0032] A polymer matrix is ​​a matrix comprising at least one polymer. The polymer matrix is ​​therefore based on a polymer composition.

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

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

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

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

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

[0038] Advantageously, N ranges 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, preferably 2 mm < Rf < 5 mm and more preferably 3 mm < Rf < 5 mm.

[0042] In one embodiment of a cable intended for reinforcing 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 metal wire element (54) is such that 0.40 mm < Dh < 2.00 mm, preferably 0.50 mm < Dh < 1.80 mm.

[0044] In one embodiment of a cable intended for reinforcing 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 one embodiment of a cable intended for reinforcing 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 one embodiment of a cable intended for reinforcing a tire for industrial vehicles chosen 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 one embodiment of a cable intended for reinforcing 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, noted D, is measured by means of a thickness comparator whose contact diameter is at least equal to 1.5 times the pitch P of winding of the wire elements (we can cite for example the model JD50 of the KAEFER brand allowing a precision of 1 / 100 of a millimeter to be achieved, equipped with a type a contact, and having a contact pressure close to 0.6N). The measurement protocol consists of three repetitions of a series of three measurements (carried out perpendicular to the cable axis and under zero tension) of which the second and third of these measurements are carried out in a direction angularly offset from the previous one by a third of a turn, by rotating the measurement direction around the cable axis.

[0053] In one embodiment of a cable intended for reinforcing 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. Here, each metal wire element is advantageously made of a metal monofilament. In a variant of this embodiment, the metal monofilament is directly coated with a layer of a metal coating comprising copper, zinc, tin, cobalt or an alloy of these metals, for example brass or bronze. In this variant, each metal wire element is then made of the metal monofilament, for example steel, forming a core, directly coated with the layer of metal coating.

[0055] In this embodiment, each elementary metal 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 tire field, namely, the NT (Normal Tensile), HT (High Tensile), ST (Super Tensile), SHT (Super High Tensile), UT (Ultra Tensile), UHT (Ultra High Tensile) and MT (Mega Tensile) grades, the use of high mechanical strengths possibly allowing 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 metal wire element is free of pre-forming marks. In other words, the cable is obtained by a process free of individual pre-forming steps for each of the metal wire elements.

[0059] As described above, the cable according to the invention is manufactured in accordance with a method and by implementing an installation described in documents WO2016083265 and WO2016083267. This method comprises a step of assembling M metallic wire elements together in a layer of the 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 elements metal wires and M2 metal 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 comprises a step of separating the transient core from the first and second assemblies. In this embodiment, the first assembly consists of M1 metal wire elements wound together and distributed in a single layer around the axis of the first assembly. Similarly, the second assembly of this embodiment consists of M2 metal wire elements wound together and distributed in a single layer around the axis of the second assembly. In other words, in this first embodiment, the transient core comprising at least one wire element, each wire element of the transient core does not belong to the first and second assemblies of M1 metal wire elements and M2 metal wire elements. We therefore have M1+M2=M.

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

[0062] Advantageously, the method comprises a step of recycling the transient nucleus during which: the transient nucleus is recovered downstream of the fractionation step, and the transient nucleus previously recovered is introduced upstream of the assembly step.

[0063] In a preferred embodiment, the step of recycling the transient nucleus can be carried out continuously, that is to say in which the transient nucleus leaving the separation step is reintroduced into the assembly step without an intermediate storage step of the transient nucleus. In another embodiment, the step of recycling the transient nucleus is discontinuous, that is to say with an intermediate storage step of the transient nucleus.

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

[0065] In a second embodiment, the step of splitting the transient assembly comprises 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, 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 one part 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 fractionation step, at least a first part of the transient core is fractionated 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 P1 metallic wire elements wound together in a helix and a central core comprising or consisting of a first part (K1 wire element(s)) of the K metallic wire elements of the transient core and around which the P1 metallic wire elements are wound together in a helix. We have P1+K1=M1.

[0068] Advantageously, during the fractionation step, at least a second part of the transient core is fractionated 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 consisting of 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 nucleus constitute the transient nucleus. Thus, the first and second parts of the transient nucleus are complementary. We therefore have K1+K2=K. Alternatively, we could have K1+K2 <K.

[0072] In a variant, the first assembly comprises a layer of P1 metallic wire elements wound together in a helix around a central core comprising or consisting of the transitional core and the second assembly comprises a layer of P2=M2 metallic wire elements wound together in a helix and devoid of 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 twisting and individual twisting about their own axis, which generates an untwisting torque on each of the metal wire elements. In another embodiment, the assembly step is performed by cabling. In this case, the metal wire elements do not undergo twisting about their own axis, due to a synchronous rotation before and after the assembly point.

[0074] Preferably, in the case of a twisting assembly step, the method comprises a step of balancing the transient assembly. Thus, the balancing step being carried out on the assembly consisting of the M metallic wire elements and the transient core, the balancing step is implicitly carried out upstream of the fractionation step.

[0075] Advantageously, the method comprises a step of balancing at least one of the first and second assemblies after the fractionation step.

[0076] Advantageously, the method comprises a step of maintaining the rotation of the first and second assemblies around their respective direction of travel. This step is carried out after the splitting step and before the step of balancing 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 in 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 comprising a tread and a crown reinforcement, two sidewalls, two beads, each sidewall connecting each bead to the crown, the crown reinforcement extending in the crown in a circumferential direction of the tire, the tire comprising a carcass reinforcement anchored in each of the beads and extending in the sidewalls and in the crown, the crown reinforcement being radially interposed between the carcass reinforcement and the tread, the crown reinforcement comprising at least one reinforced product as defined above.

[0083] Preferably, the crown reinforcement comprises a hoop reinforcement comprising at least one hoop ply and preferably a single hoop ply. The hoop reinforcement is preferably constituted by a hoop ply. This embodiment is particularly suitable for a tire and is particularly intended for industrial vehicles chosen from heavy vehicles such as "Heavy Goods Vehicles" - i.e., metro, bus, road transport equipment (trucks, tractors, trailers), off-road vehicles -, agricultural or civil engineering equipment, other transport or handling vehicles.

[0084] Preferably, the crown reinforcement comprises a working reinforcement comprising at least one working ply.

[0085] In heavy-duty applications for transporting loads, the hoop reinforcement usually comprises a hoop sheet made by circumferentially winding a hoop wire or a continuous hoop strip, forming, with the circumferential direction, angles at most equal to 5°.

[0086] In one embodiment, the hoop reinforcement is radially interposed between the two working reinforcements.

[0087] Advantageously, the hooping sheet comprises at least one reinforced product as defined above.

[0088] Preferably, the tire is for heavy goods 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 by reading the examples which follow, given solely as non-limiting examples and made with reference to the drawings in which: - figure 1 is a sectional view perpendicular to the circumferential direction of a tire according to the invention; - figure 2 is a detailed view of zone II of figure 1; - figure 3 is a sectional view of a reinforced product (R) according to the invention; - figure 4 is a schematic sectional view perpendicular to the axis of a cable to determine the distance separating 2 adjacent metallic wire elements and the angle 0; - figure 5 is a schematic sectional view perpendicular to the axis of the cable (assumed to be rectilinear and at rest) of a cable (50) according to the invention; and - figure 6 a schematic sectional view perpendicular to the axis of the cable (assumed to be straight and at rest) of a comparative cable C1.

[0090] EXAMPLE OF A TIRE ACCORDING TO THE INVENTION

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

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

[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 goods vehicles. Thus, the P tire has a size of 315 / 70 R 22.5.

[0095] The tire P comprises a crown 12 reinforced by a crown reinforcement 14, two sidewalls 16 and two beads 18, each of these beads 18 being reinforced with a annular structure, here a bead wire 20. The crown reinforcement 14 is radially surmounted by a tread 22 and joined to the beads 18 by the sidewalls 16. A carcass reinforcement 24 is anchored in the two beads 18, and is here wound around the two bead wires 20 and comprises a turn-up 26 arranged towards the outside of the tire 20 which is here shown mounted on a rim 28. The carcass reinforcement 24 is radially surmounted by the crown reinforcement 14.

[0096] The carcass reinforcement 24 comprises at least one carcass ply reinforced by radial carcass cords (not shown). The carcass cords are arranged substantially parallel to each other and extend from one bead 18 to the other so as to form an angle of between 80° and 90° with the median circumferential plane M (plane perpendicular to the axis of rotation of the tire which is located midway between the two beads 18 and passes through the middle of the crown reinforcement 14).

[0097] The tire P also includes a sealing ply 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 ply from the diffusion of air coming from the space inside the tire P.

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

[0099] The working reinforcement comprises first and second working plies, the first ply formed of metal cables oriented at an angle equal to 20°; a hoop reinforcement comprising a single hoop ply comprising a reinforced product as described below and a second working ply formed of metal cables oriented at an angle equal to 44°, crossed with the metal cables of the first working ply, the cables of each of the working layers being oriented on either side of the circumferential direction.

[0100] The crown frame 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 polymer matrix Ma.

[0103] In Figure 3, the polymer matrix Ma, the cables 50 are represented in a reference frame X, Y, Z in which the direction Y is the radial direction and the directions X and Z are the axial and circumferential directions. In Figure 3, the reinforced product R comprises several cables 50 arranged side by side in the main direction X and extending parallel to each other within the reinforced product R and collectively embedded in the polymer matrix Ma.

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

[0105] CABLE ACCORDING TO AN EMBODIMENT OF THE INVENTION

[0106] The extracted cable 50 according to the embodiment of the invention is shown in Figure 5 and the comparative cable C1 having the same characteristics as the cable 50 except the 5 max in Figure 6.

[0107] Each protective reinforcement element and each hoop reinforcement 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 in a polymer matrix, in this case in a polymer matrix respectively forming each polymer matrix of each protective ply 42, 44 and of each hoop layer 52, 54 in which the protective reinforcement and hoop reinforcement elements are respectively embedded.

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

[0109] The cable 50 comprises a 1xN structural layer 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 metal coating comprising copper, zinc, tin, cobalt or an alloy of these metals, here brass. Each metal monofilament is made of carbon steel and has a mechanical strength here equal to 3100 MPa.

[0111] [Table 1]

[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 metal wire elements for cables 50 and 60, maximum rigidity of the cable is obtained and no loss of rigidity. When there is an irregular distribution on the circumference of the cable as for cable C1, a loss of rigidity of 30% is observed.

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

Claims

CLAIMS 1. Cable extracted (50) from a polymer matrix, the extracted cable (50) comprising a single layer (52) consisting 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 helix-shaped trajectory of pitch P expressed in millimeters and helix angle a expressed in radians, around a main axis (A) substantially parallel to the substantially rectilinear direction, such that, in a section plane substantially perpendicular to the main axis (A), the distance between the center of each metallic wire element (54) of the layer (52) and the main 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,each metallic wire element (54) having a helix curvature radius Rf defined by Rf=P / (TT x Sin(2a)) in which, Dh, D, Dv, Df and Rf are expressed in millimeters:, 9 < Rf / Df < 30, and 1.30 < Dv / Df < 4.5 ; and the space between 2 adjacent metallic wire elements is defined by 5 = (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 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) such that 2.asin(Df / Dh) < 6 < 360 - 2xN*asin(Df / Dh); characterized in that: the ratio 5 max / oh r ef ranges from 1.0 to 2.9 with 5 ref being the case where the space between the N metallic wire elements is the same and 5 max being the case where the space between 2 adjacent metallic wire elements is greater than 5 ref; and in which N ranges from 4 to 15.

2. Extracted cable (50) according to the preceding claim, in which the ratio 5 max / ôref ranges 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, wherein 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, in which the helix curvature 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, in which 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, in which 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, in which 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

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