Reinforced product with fixed cable geometry exhibiting very high bimodulus behavior for cable deformability in off-road use

Abstract

The invention relates to a reinforced product (R) comprising a polymer matrix (Ma) and at least one cable (50) comprising a single layer made up of N metallic reinforcing elements being: either metallic wires (F) having a diameter Df, with the metallic reinforcing elements (54) having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires (F) of the layer in a plane perpendicular to the main axis of the cable and a diameter D which is the outside diameter of the cable (50);- or strands (T) wound helically around a principal axis (A), each strand (T) comprising a single layer (56) made up of M>1 metallic wires (FT) wound helically around an axis (B) having a diameter Df with metallic reinforcing elements (54) having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires (FT) of layer (56) in a plane perpendicular to the principal axis of the strand (T) and a diameter D which is the outside diameter of the strand (T); with D, Dh and Df expressed in millimeters: - 0.30 < Jr ≤ 0.60 With Jr=N / (π x (D-Df)) x (Dh x Sin(π / N) – (Df / Cos(α x π / 180))), α being the helix angle, expressed in degrees, of each metallic wire; - the polymer matrix (Ma) presents a secant elastic modulus MA10 at 10% strain ranging from 2.5 to 18.0 MPa;- The reinforced product (R) has a modulus ratio Emax to Emin such that 1 < Emax / Emin < 7, where Emin is the minimum elastic modulus secant in tension and Emax is the maximum modulus tangent to the same force-stretch curve; and - the reinforced product (R) has a structural elongation As such that 0 < As < 5%. Figure for the abbreviation: Fig 3;

Description

Title of the invention: Reinforced product with fixed cable geometry exhibiting very strong bimodule behavior for cable deformability in off-road use

[0001] The present invention relates to a reinforced product and a tire comprising such a product.

[0002] Although not limited to this type of application, the invention will be more particularly described with reference to a tire for heavy industrial vehicles.

[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 bimodule 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 protective crown ply which requires a marked bi-module behavior and a high elongation for the deformability of the tire in off-road use when passing an obstacle and therefore a more or less marked bi-module behavior. This step can prove to be long and tedious to select the cable of the reinforced product meeting the specifications.

[0006] Usually, to vary the rigidity 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. Several cable geometries are therefore necessary to vary the rigidity of the reinforced product in order to adapt the reinforced product to the intended use.

[0007] The invention aims to provide a reinforced product whose control of rigidity and bi-module behavior is simplified by modifying the polymer matrix without modifying the cable.

[0008] To this end, the invention relates to a reinforced product comprising a polymer matrix and at least one cable comprising a single layer consisting of N metallic reinforcing elements wound in a helix, each metallic reinforcing element of the layer describing, when the cable extends in a substantially rectilinear direction, a trajectory in the form of a helix around an axis. principal substantially parallel to the substantially rectilinear direction, so that, in a section plane substantially perpendicular to the principal axis, the distance between the center of each metallic reinforcing element of the layer and the principal axis is substantially constant and equal for all the metallic reinforcing elements of the layer, the metallic reinforcing elements being: - or metal wires having a diameter Df with the metal reinforcing elements having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires of the layer in a plane perpendicular to the main axis of the cable and a diameter D which is the outside diameter of the cable; - or strands wound helically around a main axis, each strand comprising a single layer consisting of M>1 metal wires wound helically around an axis having a diameter Df with the metal reinforcing elements having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires of the layer in a plane perpendicular to the main axis of the strand and a diameter D which is the outside diameter of the strand; with D, Dh and Df expressed in millimeters: - 0.30 < Jr < 0.60 With Jr=N / (ir x (D-Df)) x (Dh x Sin(ir / N) - (Df / Cos(ax jt / 1 80))), a being the helix angle, expressed in degrees, of each metal wire; - the polymer matrix has a secant elastic modulus MA 10 at 10% deformation % determined according to standard NF ISO 37 of February 2018 ranging from 2.5 to 18.0 MPa; - the reinforced product has a modulus ratio Emax to Emin such that 1< Emax / Emin <7 with Emin being the minimum secant elastic modulus in tension, i.e. the slope of the straight line connecting the origin of the stress-elongation curve (0%; OMPa) obtained under the conditions of standard ASTM D 2969 - 04 of 2014 and Emax being the maximum tangent modulus of the same force-elongation curve; and - the reinforced product has a structural elongation As such that 0< As < 5% determined by the ASTM D2969-04 standard of 2014.

[0009] The inventors behind the invention realized that by fixing the geometry of the cable and in particular its relative play, it was possible to control, on the one hand, the rigidity of the reinforced product by varying the rigidity of the polymer matrix and, on the other hand, to vary the bimodule behavior of the reinforced product, still by varying the rigidity of the polymer matrix. Thus, the same cable can be used for different positions in the tire by varying the rigidity of the polymer matrix.

[0010] The reinforced product according to the invention therefore makes it possible to significantly vary the rigidity of the reinforced product without changing the steel grade or varying the mass of metal used.

[0011] By elastomeric matrix is ​​meant a matrix with elastomeric behavior resulting from the crosslinking of an elastomeric composition. The elastomeric matrix is ​​thus based on the elastomeric composition. Just like the elastomeric matrix, the filling material is based on an elastomeric composition, here the same composition as that of the matrix in which the cable is embedded.

[0012] The values ​​of the characteristics Dh, D, Df, Dv, Rf and a as well as the other characteristics described below are measured on or determined from the cables either directly after manufacture, that is to say before any step of embedding in an elastomeric matrix, or extracted from an elastomeric matrix, for example from a tire, and having then undergone a cleaning step during which any elastomeric matrix is ​​removed from the cable, in particular any material present inside the cable. To guarantee an original state, the adhesive interface between each metal reinforcing 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 the elongation of the cables, are cancelled out by the extraction of the ply and the cable which, upon extraction, substantially regain their characteristics from before the shaping step.

[0013] The cable according to the invention comprises a single layer of helically wound metal reinforcing elements. In other words, the cable according to the invention comprises only one, not two, nor more than two layers of helically wound metal reinforcing elements. The layer is made up of metal reinforcing elements, i.e. several metal reinforcing elements, not a single metal reinforcing 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 reinforcing elements, in other words the cable does not comprise any other metal reinforcing element than those of the layer.

[0014] In one embodiment, the cable is single helix. By definition, a single helix cable is a cable in which the axis of each metal reinforcing element of the layer describes a single helix, unlike a double helix cable in which the axis of each metal reinforcing 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 reinforcing element of the layer describing a helix-shaped path around a main axis substantially parallel to the substantially rectilinear direction so that, in a section plane substantially perpendicular to the main axis, the distance between the center of each metal reinforcing element of the layer and the principal axis is substantially constant and equal for all the metal reinforcing elements of the layer. On the contrary, when a double helix cable extends in a substantially rectilinear direction, the distance between the center of each metal reinforcing element of the layer and the substantially rectilinear direction is different for all the metal reinforcing elements of the layer.

[0015] In another embodiment of the invention, the cable is double helix.

[0016] The cable according to the invention is devoid of a central metallic core. We speak of also an IxN structure cable or even an open-cord cable. In the cable according to the invention defined above, the internal vault is empty and therefore devoid of any filling material, in particular devoid of any elastomeric composition. We then speak of a cable devoid of filling material.

[0017] The arch of the cable according to the invention is delimited by the metal reinforcement elements and corresponds to the volume delimited by a theoretical circle, on the one hand, radially inside each metal reinforcement element and, on the other hand, tangent to each metal reinforcement element. The diameter of this theoretical circle is equal to the arch diameter Dv.

[0018] 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 reinforcing element has a circular section.

[0019] By definition, the term 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 reinforcing 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 of stainless steel (by definition, steel comprising at least 10.5% chromium).

[0020] The structural elongation As, a quantity well known to those skilled in the art, is determined for example by applying the ASTM D2969-04 standard of 2014 to a reinforced product tested so as to obtain a force-elongation curve. The As is deduced on the curve obtained as the elongation, in %, corresponding to the point of intersection of the tangent to the elastic part of the force-elongation curve with the axis of elongations. As a reminder, a force-elongation curve includes, moving towards increasing elongations, a structural part, an elastic part and a plastic part. The structural part corresponds to a structural elongation of the cable resulting from the bringing together of the different metallic reinforcing elements constituting the cable. In certain embodiments, the layer of N metallic reinforcing elements is deconstructed at the end of the structural part, due to the relatively low relative radial clearance Jr, causing a punctual increase in the modulus of the cable. The elastic part corresponds to an elastic elongation resulting from the construction of the cable, in particular the angles of the different layers and the diameters of the wires. The plastic part corresponds to the plastic elongation resulting from the plasticity (irreversible deformation beyond the elastic limit) of one or more metallic reinforcing elements.

[0021] The relative radial clearance Jr 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. Thus, the higher Jr, the greater the space separating two adjacent metal wire elements compared to the maximum number of metal wire elements that the layer could accommodate. Conversely, the smaller Jr, the smaller the space separating two adjacent metal wire elements compared to the maximum number of metal wire elements that the layer could accommodate. In the interval according to the invention, Jr makes it possible to maximize the number of metal wire elements present on the layer and therefore the reinforcement capacity of the cable without, however, deteriorating the capacity to accommodate longitudinal compression deformations.

[0022] The Emax / Emin ratio is determined from the force-elongation curve obtained under the conditions of the ASTM D 2969 - 04 standard of 2014 as shown in Figures 7 and 8.

[0023] Emin is the minimum secant elastic modulus in tension, i.e. the slope of the straight line connecting the origin of the stress-elongation curve (0%; OMPa) obtained under the conditions of standard ASTM D 2969 - 04 of 2014, expressed in GPa.

[0024] Emax is the maximum tangent modulus of this same force-elongation curve, expressed in GPa.

[0025] The helix angle a is a quantity well known to those skilled in the art and can be determined by the following iterative calculation comprising 3 iterations and in which the index i indicates the number of iteration 1, 2 or 3. Knowing the structural elongation As expressed in %, the helix angle a(i) is such that a(i)=Arcos [ (100 / (100+As) x Cos [ Arctan ( (ji x Df) / (P x Cos(a(i-1)) x Sin(ir / N)) ] ], formula in which P is the pitch expressed in millimeters at which each metal reinforcing element is wound, N is the number of metal reinforcing elements in the layer, Df is the diameter of each metal reinforcing element expressed in millimeters, Arcos, Cos, Arctan, and Sin denoting the arcosine, cosine, arctangent, and sine functions respectively. For the first iteration, i.e., for calculating a(l), we take a(0)=0. In the third iteration, we obtain a(3)=a with at least one significant figure after the decimal point when a is expressed in degrees.

[0026] The helix diameter Dh, expressed in millimeters, is calculated according to the relation Dh=P x Tan(a) / ir in which P is the pitch expressed in millimeters at which each metal reinforcing element is wound, a is the helix angle of each metal reinforcing element determined above and Tan the tangent function. The helix diameter Dh corresponds to the diameter of the theoretical circle passing through the centers of the metal reinforcing elements of the layer in a plane perpendicular to the axis of the cable.

[0027] The arch diameter Dv, expressed in millimeters, is calculated according to the relationship Dv=Dh-Df in which Df is the diameter of each metal reinforcing element and Dh the helix diameter, both expressed in millimeters.

[0028] The diameter or apparent diameter, noted D of the cable when the metallic reinforcing elements are wires, is measured by means of a thickness comparator whose contact diameter is at least equal to 1.5 times the winding pitch P of the wire elements (one can cite for example the model JD50 of the KAEFER brand allowing to achieve a precision of 1 / 100 of a millimeter, 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 axis of the cable 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 the rotation of the measurement direction around the axis of the cable or strand.

[0029] The diameter or apparent diameter, noted D of the strand when the reinforcing elements are strands, is measured by wedging the cable between two perfectly straight bars of length 200 mm and by measuring the spacing in which the cable is embedded using the comparator described below. We can cite for example the model JD50 / 25 of the KAEFER brand allowing to achieve a precision of 1 / 100 of a millimeter, equipped with type a touch, 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 axis of the cable and under zero tension).

[0030] It is recalled that the pitch at which each metal reinforcing 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 the end of which the wire element having this pitch makes a complete turn around said axis of the cable.

[0031] The optional features described below may be combined with each other. with others to the extent that such combinations are technically compatible.

[0032] In an advantageous embodiment, all the metal wires have the same diameter Df.

[0033] The cable of the reinforced product 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 reinforcing elements are wound in a helix, the assembly step being preceded by a step of preforming the metal reinforcing 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 making it possible to achieve high structural elongations 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.

[0034] By definition, the MA10 is the secant elastic modulus in tension of a vulcanized polymer matrix measured at 10% elongation from a stress-elongation curve produced according to the recommendations of the NF ISO 37 standard of February 2018. This is the elastic modulus of the mixture measured during a uniaxial tensile experiment, at an elongation value of 0.1 (i.e. 10% elongation, expressed as a percentage). A constant uniaxial tensile speed is imposed on the test piece, and its elongation and force are measured. The measurement is carried out using an INSTRON type tensile machine, at a temperature of 23°C, and a relative humidity of 50% (ISO 23529 standard). The conditions for measuring and using the results to determine the elongation and the stress are as described in the standard NF ISO 37: 2018-02. The stress is determined for an elongation of 0.1 and the elastic modulus at 10% is calculated by taking the ratio of this stress value to the elongation value. A person skilled in the art will know how to choose and adapt the dimensions of . the test piece depending on the quantity of mixture accessible and available, particularly in the case of taking samples from a finished product such as a tire.

[0035] Any interval of values ​​designated by the expression "between a and b" represents the domain of values ​​going from more than a to less than b (i.e., limits a and b excluded) while any interval of values ​​designated by the expression "from a to b" means the domain of values ​​going from a up to b (i.e., including the strict limits a and b).

[0036] By radial cut or radial section is meant here a cut or a section along a plane which includes the axis of rotation of the tire.

[0037] By axial direction is meant the direction substantially parallel to the axis of rotation of the tire.

[0038] By circumferential direction is meant the direction which is substantially perpendicular to both the axial direction and a radius of the tire (in other words, tangent to a circle whose center is on the axis of rotation of the tire).

[0039] By radial direction is meant the direction along a radius of the tire, that is to say any direction intersecting the axis of rotation of the tire and substantially perpendicular to this axis.

[0040] The median plane (denoted M) is the plane perpendicular to the axis of rotation of the tire which is located midway between the two beads and passes through the middle of the crown reinforcement.

[0041] The equatorial circumferential plane (denoted E) of the tire is the theoretical plane passing through the equator of the tire, perpendicular to the median plane and to the radial direction. The equator of the tire is, in a circumferential section plane (plane perpendicular to the circumferential direction and parallel to the radial and axial directions), the axis parallel to the axis of rotation of the tire and located equidistant between the radially outermost point of the tread intended to be in contact with the ground and the radially innermost point of the tire intended to be in contact with a support, for example a rim, the distance between these two points being equal to H.

[0042] By orientation of an angle, we mean the direction, clockwise or anti-clockwise, in which it is necessary to turn from a reference line, here the circumferential direction of the tire, defining the angle to reach the other line defining the angle.

[0043] Advantageously, the metal reinforcing elements define an internal arch of the cable of diameter Dv, each metal reinforcing element having a diameter Df and a helix curvature radius Rf defined by Rf=P / (ir x Sin(2a)) with P the pitch of each metal reinforcing element expressed in millimeters and a the helix angle of each metal reinforcing element (54) and Dv=Dh-Df, in which Dv, Dh and Df being expressed in millimeters: 1.30 < Dv / Df < 4.50.

[0044] The radius of curvature Rf, expressed in millimeters, is calculated according to the relation Rf=P / (ir x Sin(2a)) in which P is the pitch expressed in millimeters of each metal reinforcement element, a is the helix angle of each metal reinforcement element and Sin the sine function.

[0045] Advantageously, 9 < Rf / Df < 30.

[0046] Preferably, the total elongation At >1.5% determined by ASTM D2969-04 of 2014.

[0047] Advantageously, the helix diameter Dh of each metal reinforcing element (54) is such that 0.70 mm < Dh < 1.60 mm, preferably 0.75 mm < Dh < 1.60 mm and more preferably 0.80 mm < Dh < 1.60 mm.

[0048] Advantageously, Df is such that 0.10 mm < Df < 0.50 mm, preferably 0.15 mm < Df < 0.50 mm and more preferably 0.15 mm < Df < 0.45 mm.

[0049] Advantageously, Dv is such that Dv > 0.40 mm, preferably 0.50 mm < Dv < 1.30 mm.

[0050] Preferably, each metal reinforcing element is wound at a pitch P such that 3 mm < P < 15 mm, preferably 5 mm < P < 13 mm and more preferably 7 mm < P < 11 mm. It can also be seen that the reinforced product according to the invention allows a wider range of adjustment of the rigidity of the reinforced product than with other elastic cables by varying the pitch of the fabric.

[0051] Advantageously, the diameter of the cable or strand D < 2.10 mm, preferably 0.90 mm < D < 2.10 mm and more preferably 0.95 mm < D < 2.05 mm.

[0052] In a first preferred embodiment, each metal reinforcing element of the cable is a metal wire with N ranging from 3 to 18 and preferably from 4 to 15.

[0053] In a second preferred embodiment, each metal reinforcing element of the cable is a strand with N ranging from 3 to 5, M ranging from 3 to 18 and preferably from 4 to 15.

[0054] In this second preferred embodiment, advantageously, the strands define an internal arch of the cable of diameter Dvc, each strand having a diameter D and a helix curvature radius Rt defined by Rt=Pe / (ir x Sin(2ae)) with Pe the pitch of each strand expressed in millimeters and ae the helix angle of each strand (T), Dvc, D and Rt being expressed in millimeters, the cable satisfies the following relationships: 5 < Rt / D < 750 and 0.10 < Dvc / D < 0.50.

[0055] The cable of the product reinforced according to this second embodiment has excellent longitudinal compressibility and, all things being equal, a relatively small diameter.

[0056] On the one hand, the inventors behind the invention hypothesize that, due to a sufficiently high radius of curvature Rt compared to the diameter D of each strand, the cable is sufficiently ventilated, thus reducing the risk of buckling, due to the relatively large distance of each strand from the longitudinal axis of the cable, a distance allowing the strands to accommodate, by their helix, relatively high longitudinal compressive deformations. On the contrary, the radius of curvature Rt of each strand of the cable of the state of the art being relatively small compared to the diameter D, the metallic wire elements are closer to the longitudinal axis of the cable and can accommodate, by their helix, much lower longitudinal compressive deformations.

[0057] On the other hand, for a radius of curvature Rt of each strand that is too high, the cable according to the invention would have insufficient longitudinal compression rigidity to ensure a reinforcing role, for example of tires.

[0058] Furthermore, for an internal arch diameter Dvc that is too high, the cable would have, relative to the diameter of the strands, a diameter that is too high.

[0059] The values ​​of the characteristics Dt, Dvc and Rt as well as the other characteristics described above are measured on or determined from the cables either directly after manufacture, that is to say before any step of embedding in an elastomeric matrix, or extracted from an elastomeric matrix, for example from a tire, and having then undergone a cleaning step during which any elastomeric matrix is ​​removed from the cable, in particular any material present inside the cable. To guarantee an original state, the adhesive interface between each metal 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 the elongation of the cables, are cancelled out by the extraction of the ply and the cable which, upon extraction, substantially regain their characteristics from before the shaping step.

[0060] The arch of the cable of the reinforced product according to this second embodiment is delimited by the strands and corresponds to the volume delimited by a theoretical circle, on the one hand, radially inside each strand and, on the other hand, tangent to each strand. The diameter of this theoretical circle is equal to the arch diameter Dvc.

[0061] The helix angle of each strand ae is a quantity well known to those skilled in the art and can be determined by the following calculation: tan ae = 2xir x Re / Pe, formula in which Pe is the pitch expressed in millimeters in which each strand is wound, Re is the helix radius of each strand expressed in millimeters, and tan denotes the tangent function, ae is expressed in degrees.

[0062] The helix diameter De, expressed in millimeters, is calculated according to the relationship De=Pe x Tan(ae) / ir in which Pe is the pitch expressed in millimeters at which each strand is wound, ae is the helix angle of each strand determined above and Tan the tangent function. The helix diameter De corresponds to the diameter of the theoretical circle passing through the centers of the strands of the layer in a plane perpendicular to the main axis of the cable.

[0063] The arch diameter Dvc, expressed in millimeters, is calculated according to the relation Dvc=De-D in which t is the diameter of each strand and De the helix diameter, both expressed in millimeters.

[0064] The radius of curvature Rt, expressed in millimeters, is calculated according to the relation Rt=Pe / (ir x Sin(2ae)) in which Pe is the pitch expressed in millimeters of each strand, ae is the helix angle of each strand and Sin the sine function.

[0065] It is recalled that the pitch at which each strand is wound is the length traveled by this wire element, measured parallel to the axis of the cable in which it is located, at the end of which strand having this pitch makes a complete turn around said axis of the cable.

[0066] In this second preferred embodiment, advantageously, the pitch of each strand Pe ranges from 20 mm to 120 mm.

[0067] PNEUMATIC ACCORDING TO THE INVENTION

[0068] The invention also relates to a tire comprising at least one reinforced product as defined above.

[0069] 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.

[0070] In a preferred embodiment, the crown reinforcement comprises a protective reinforcement and a working reinforcement, the protective reinforcement comprising at least one reinforced product as defined above, the protective reinforcement being radially interposed between the tread and the working reinforcement.

[0071] The reinforced product is particularly intended for industrial vehicles chosen from heavy vehicles such as "Heavy Goods Vehicles" - i.e., metro, bus, road transport vehicles (trucks, tractors, trailers), off-road vehicles -, agricultural or civil engineering vehicles, other transport or handling vehicles.

[0072] Preferably, the tire is for a civil engineering type vehicle. Thus, the tire has a dimension in which the diameter, in inches, of the seat of the rim on which the tire is intended to be mounted is greater than or equal to 25 inches, preferably from 39 to 63 inches.

[0073] The invention will be better understood by reading the examples which follow, given solely as non-limiting examples and made with reference to the drawings in which: - [Fig.l] is a sectional view perpendicular to the circumferential direction of a tire (10) according to the invention; - [Fig.2] is a detailed view of zone II of [Fig.l]; - [Fig.3] is a sectional view of a reinforced product (R) according to the invention; - [Fig.4] is a schematic sectional view perpendicular to the axis of the cable (assumed to be rectilinear and at rest) of a cable (50) of the reinforced product (R) according to a first embodiment of the invention; - [Fig.5] is a view similar to that of [Fig.4] of a cable (50') of the reinforced product (R) according to a second embodiment of the invention; - [Fig.6] illustrates stress-elongation curves for reinforced products (RI; RI'; RI”; RI'”) according to a first embodiment of the invention comprising the cable (50); - [Fig.7] illustrates part of the stress-elongation curve for a reinforced product (RI) according to a first embodiment of the invention comprising the cable (50) and schematically represents the modules Emin and Emax; and - [Fig.8] illustrates part of the stress-elongation curve for a reinforced product (R2) according to a second embodiment of the invention comprising the cable (50') and schematically represents the modules Emin and Emax.

[0074] EXAMPLE OF A TIRE ACCORDING TO THE INVENTION

[0075] In Figures 1 and 2, a reference X, Y, Z is shown corresponding to the usual axial (X), radial (Y) and circumferential (Z) orientations of a tire.

[0076] 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.

[0077] Figures 1 and 2 show a tire according to the invention and designated by the general reference 10.

[0078] The tire 10 is for a heavy vehicle of the civil engineering type, for example of the “dumper” type. Thus, the tire 10 has a dimension of the 53 / 80R63 type.

[0079] The tire 10 comprises a crown 12 reinforced by a crown reinforcement 14, two sidewalls 16 and two beads 18, each of these beads 18 being reinforced with an annular structure, here a bead wire 20. The crown reinforcement 14 is radially surmounted by a tread 22 and joined to the beads 18 by the sidewalls 16. A carcass reinforcement 24 is anchored in the two beads 18, and is here wound around the two bead wires 20 and comprises a turn-up 26 arranged towards the outside of the tire 20 which is here shown mounted on a rim 28. The carcass reinforcement 24 is radially surmounted by the crown reinforcement 14.

[0080] The carcass reinforcement 24 comprises at least one carcass ply 30 reinforced by radial carcass cords (not shown). The carcass cords are arranged substantially parallel to each other and extend from one bead 18 to the other so as to form an angle of between 80° and 90° with the median circumferential plane M (plane perpendicular to the axis of rotation of the tire which is located midway between the two beads 18 and passes through the middle of the crown reinforcement 14).

[0081] The tire 10 also comprises a sealing ply 32 made of an elastomer (commonly called inner rubber) which defines the radially inner face 34 of the tire 10 and which is intended to protect the carcass ply 30 from the diffusion of air coming from the space inside the tire 10.

[0082] The crown reinforcement 14 comprises, radially from the outside to the inside of the tire 10, a protective reinforcement 36 arranged radially inside the tread 22, a working reinforcement 38 arranged radially inside the protective reinforcement 36 and an additional reinforcement 40 arranged radially inside the working reinforcement 38. The protective reinforcement 36 is thus radially interposed between the tread 22 and the working reinforcement 38. The working reinforcement 38 is radially interposed between the protective reinforcement 36 and the additional reinforcement 40.

[0083] The protective reinforcement 36 comprises first and second protective plies 42, 44 comprising protective metal cables, the first ply 42 being arranged radially inside the second ply 44. Optionally, the protective metal cables make an angle at least equal to 10°, preferably ranging from 10° to 35° and preferentially from 15° to 30° with the circumferential direction Z of the tire.

[0084] The working reinforcement 38 comprises first and second working plies 46, 48, the first ply 46 being arranged radially inside the second ply 48. Each ply 46, 48 comprises at least one cable 50. Optionally, the metal working cables 50 are crossed from one working ply to the other and make an angle at most equal to 60°, preferably ranging from 15° to 40° with the circumferential direction Z of the tire.

[0085] The additional reinforcement 40, also called a limiting block, the function of which is to partially absorb the mechanical stresses of inflation, comprises, for example and in a manner known per se, additional metal reinforcing elements, for example as described in FR 2 419 181 or FR 2 419 182 making an angle at most equal to 10°, preferably ranging from 5° to 10° with the circumferential direction Z of the tire 10.

[0086] The crown frame also comprises a hoop frame 17 comprising a single hoop sheet 19 comprising a reinforced product as described below.

[0087] The crown reinforcement 14 is surmounted by the tread 20. Here, the hoop reinforcement 17, here the hoop ply 19, is radially interposed between the working reinforcement 16 and the tread 20.

[0088] EXAMPLE OF REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0089] [Fig. 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.

[0090] In [Fig. 3], the polymer matrix Ma is represented, the cables 50 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 [Fig. 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.

[0091] Here, the polymer matrix Ma is an elastomeric matrix based on an elastomeric composition.

[0092] The polymer matrix has a secant elastic modulus MA 10 at 10% elongation determined according to the NF ISO 37 standard of February 2018 ranging from 2.5 to 18.0 MPa.

[0093] The reinforced product R is the reinforced product RL Here for the reinforced product RI, the secant elastic modulus MA10 at 10% elongation is 2.5 MPa. The reinforced product RI has a modulus ratio Emax to Emin such that 1< Emax / Emin <7 with Emin being the minimum secant elastic modulus in tension, i.e. the slope of the straight line connecting the origin of the stress-elongation curve (0%; OMPa) obtained under the conditions of the standard ASTM D 2969 - 04 of 2014 and Emax being the maximum tangent modulus of the same force-elongation curve shown in [Fig.7].

[0094] Here Emin= 7.5 GPa.

[0095] Here Emax=46 GPa.

[0096] And Emax / Emin = 6 between 1 and 7.

[0097] The reinforced product RI has a structural elongation As such that 0 < As < 5% determined by the standard ASTM D2969-04 of 2014.

[0098] Here As= 2.9%. REINFORCED PRODUCT CABLE ACCORDING TO A FIRST EMBODIMENT OF THE INVENTION

[0099] [Fig.4] shows the cable 50 according to a first embodiment of the reinforced product of the invention.

[0100] The cable 50 comprises a single layer consisting of N = 8 reinforcement elements metal reinforcements 54 wound in a helix, each metal reinforcement element 54 of the layer 52 describing, when the cable 50 extends in a substantially rectilinear direction, a helix-shaped trajectory around a main axis (A) substantially parallel to the substantially rectilinear direction, so that, in a section plane substantially perpendicular to the main axis (A), the distance between the center of each metal reinforcement element 54 of the layer 52 and the main axis (A) is substantially constant and equal for all the metal reinforcement elements 54 of the layer 52,the metal reinforcing elements 54 being metal wires F (here 8 metal wires) having a diameter Df with the metal reinforcing elements 54 having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires F of the layer in a plane perpendicular to the main axis of the cable and a diameter D which is the outside diameter of the cable 50 with D, Dh and Df being expressed in millimeters: - 0.30 < Jr < 0.60, With Jr=N / (ir x (D-Df)) x (Dh x Sin(ir / N) - (Df / Cos(ax jt / 1 80))), a being the helix angle, expressed in degrees, of each metal wire F.

[0101] Here Jr=0.34. REINFORCED PRODUCT CABLE ACCORDING TO A SECOND EMBODIMENT OF THE INVENTION

[0102] [Fig.5] shows the cable 50' according to a second embodiment of the reinforced product of the invention.

[0103] The cable 50' comprises a single layer consisting of N = 3 metal reinforcing elements 54 wound in a helix, each metal reinforcing element 54 of the layer 52 describing, when the cable 50' extends in a substantially rectilinear direction, a helix-shaped trajectory 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 metal reinforcing element 54 of the layer 52 and the main axis (A) is substantially constant and equal for all the metal reinforcing elements 54 of the layer 52, the metal reinforcing elements 54 being strands T (here 3 strands) wound in a helix around a main axis (A),each strand T comprising a single layer 56 made up of M>1 of metal wires FT wound in a helix around an axis (B) having a diameter Df with the metal reinforcing elements 54 having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires FT of the layer 56 in a plane perpendicular to the main axis of the strand T and a diameter D which is the external diameter of the strand T with D, Dh and Df being expressed in millimeters: , - 0.30 < Jr < 0.60 With Jr=N / (ir x (D-Df)) x (Dh x Sin(ir / N) - (Df / Cos(ax jt / 180))), a being the helix angle, expressed in degrees, of each metal wire F.

[0104] Here Jr=0.34.

[0105]

[0106] METHOD FOR MANUFACTURING THE REINFORCED PRODUCT SEEON UE FIRST EMBODIMENT OF THE INVENTION

[0107] The cable 50 of the reinforced product RI according to the first embodiment is produced according to the method described in application WO 2020 / 021006 by implementing an installation described in documents WO2016083265 and WO2016083267.

[0108] The reinforced product RI is then obtained by embedding the cable 50 in a polymer matrix Ma. Here, the polymer matrix Ma is an elastomeric matrix.

[0109] METHOD FOR MANUFACTURING THE REINFORCED PRODUCT ACCORDING TO THE SECOND EMBODIMENT OF THE INVENTION

[0110] The cable 50' of the reinforced product R2 according to the second embodiment is produced according to the method described in application WO2021140287.

[0111] The reinforced product R2 is then obtained by embedding the cable 50' in a polymer matrix Ma. Here, the polymer matrix Ma is an elastomeric matrix.

[0112] COMPARATIVE TESTS

[0113] Tables 1 and 2 below summarize the characteristics for the reinforced products of the first and second embodiments of the invention.

[0114] The stress-elongation curves of the reinforced products RI, RI', RI” and RI”' with the cable 50 according to the first embodiment of the invention were plotted by applying the standard ASTM D 2969 - 04 of 2014 as shown in [Fig.6] and the ratio Emax / Emin as determined in [Fig.7] for RI was determined, as well as the structural elongation As.

[0115] The results have been collected in Table 1 below.

[0116] [Tables 1] Reinforced product RI RI' RI” RI'” cable 50 50 50 50 N / cable direction 8 / S 8 / S 8 / S 8 / S Df(mm) 0.35 0.35 0.35 0.35 Dh (mm) 1.59 1.59 1.59 1.59 D (mm) 1.89 1.89 1.89 1.89 a(°) 27.2 27.2 27.2 27.2 Jr 0.34 0.34 0.34 0.34 MA10 (Mpa) 2.5 6.0 10.7 18.0 As (%) 2.9 2.8 1.9 1.4 Dv (mm) 1.24 1.24 1.24 1.24 RF (mm) 3.79 3.79 3.79 3.79 P (mm) 9.7 9.7 9.7 9.7 Dv / Df 3.54 3.54 3.54 3.54 Rf / Df 10.8 10.8 10.8 10.8 At% 7.6 7.2 6.4 5.8 E min (GPa) 7.5 9.0 13.0 20.0 Emax (GPa) 46 49 50 55 Emax / Emin 6.1 5.4 3.8 2.8

[0117] The stress-elongation curve of the reinforced product R2 with the 50' cable according to the second embodiment of the invention was plotted by applying the ASTM D 2969 - 04 of 2014 standard and the Emax / Emin ratio as shown in [Fig.8] was determined, as well as the structural elongation As.

[0118] The ratio Emax / Emin was also determined, as well as the structural elongation As for the reinforced product R2'.

[0119] The results have been collected in Table 2 below for the reinforced products R2 and R2'.

[0120] [Tables2] Reinforced product R2 R2' cable 50' 50' N / cable direction 3 / Z 3 / ZM / strand direction T 8 / S 8 / S Dvc (mm) 0.30 0.30 Pe (mm) 80 80 ae (°) 4.9 4.9 Rt (mm) 149 149 Df(mm) 0.35 0.35 Dh (mm) 1.59 1.59 D (mm) 1.89 1.89 a(°) 27.2 27.2 Jr 0.34 0.34 MA10 (Mpa) 10.7 18 As (%) 1.9 1.2 Dv (mm) 1.24 1.24 Rf (mm) 3.79 3.79 P (mm) 9.7 9.7 Rt / D 79 79 Dvc / D 0.16 0.16 Dv / Df 3.54 3.54 Rf / Df 10.8 10.8 At% 6.2 5.0 E min (GPa) 12 19 Emax (GPa) 48 53 Emax / Emin 4.0 2.8

[0121] Tables 1 and 2 show that the reinforced products RI, RI', RI”, RI”', R2 and R2' according to the invention present a reinforced product using a cable with predetermined geometry, in particular due to its relative play Jr, the rigidity and bi-module behavior of which can be controlled by modifying the polymer matrix without making any modifications. cable fixation.

[0122] Thus, the reinforced products according to the invention make it possible to solve the problems mentioned in the preamble.

[0123] The invention is not limited to the embodiments previously described.

Claims

Claims

1. Reinforced product (R), characterized in that it comprises a polymer matrix (Ma) and at least one cable (50; 50') comprising a single layer (52) consisting of N metal reinforcing elements (54) wound in a helix, each metal reinforcing element (54) of the layer (52) describing, when the cable (50; 50') extends in a substantially rectilinear direction, a helix-shaped trajectory around a main axis (A) substantially parallel to the substantially rectilinear direction, so that, in a section plane substantially perpendicular to the main axis (A), the distance between the center of each metal reinforcing element (54) of the layer (52) and the main axis (A) is substantially constant and equal for all the metal reinforcing elements (54) of the layer (52), the metal reinforcing elements (54) being: - or metal wires (F) having a diameter Df with the metal reinforcing elements (54) having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires (F) of the layer in a plane perpendicular to the main axis of the cable and a diameter D which is the external diameter of the cable (50); - or strands (T) wound in a helix around a main axis (A), each strand (T) comprising a single layer (56) made up of M>1 metal wires (FT) wound in a helix around an axis (B) having a diameter Df with the metal reinforcing elements (54) having a diameter Dh which is the diameter of the theoretical circle passing through the centers of the wires (FT) of the layer (56) in a plane perpendicular to the main axis of the strand (T) and a diameter D which is the outside diameter of the strand (T); with D, Dh and Df expressed in millimeters: - the relative radial play of the Jr cable is such that 0.30 < Jr < 0.60 With Jr=N / (ir x (D-Df)) x (Dh x Sin(ir / N) - (Df / Cos(ax jt / 1 80))), a being the helix angle, expressed in degrees, of each metal wire (F); - the polymer matrix (Ma) has a secant elastic modulus MA10 at 10% deformation determined according to the NF ISO 37 standard of February 2018 ranging from 2.5 to 18.0 MPa; - the reinforced product (R) has a modulus ratio Emax to Emin such that 1< Emax / Emin <7 with Emin being the minimum secant elastic modulus in tension, i.e. the slope of the straight line connecting the origin of the stress-elongation curve (0%; OMPa) obtained under the conditions of the ASTM D 2969-04 of 2014 standard and Emax being the maximum tangent modulus of the same force-elongation curve; and - the reinforced product (R) has a structural elongation As such that 0< As < 5% determined by the ASTM D2969-04 of 2014 standard.

2. Reinforced product (R) according to the preceding claim, in which the metal reinforcing elements (54) define an internal arch (58) of the cable of diameter Dv, each metal reinforcing element (54) having a diameter Df and a helix curvature radius Rf defined by Rf=P / (ir x Sin(2a)) with P the pitch of each metal reinforcing element expressed in millimeters and a the helix angle of each metal reinforcing element (54) and Dv=Dh-Df, in which Dv, Dh and Df being expressed in millimeters: 1.30 < Dv / Df < 4.

50.

3. Reinforced product (R) according to the preceding claim, in which 9 < Rf / Df < 30.

4. A reinforced product (R) according to any preceding claim, wherein the total elongation At >1.5% determined by ASTM D2969-04 of 2014.

5. Reinforced product (R) according to any one of the preceding claims, wherein the helix diameter Dh of each metal reinforcing element (54) is such that 0.70 mm < Dh < 1.60 mm, preferably 0.75 mm < Dh < 1.60 mm and more preferably 0.80 mm < Dh < 1.60 mm.

6. Reinforced product (R) according to any one of the preceding claims, in which Df is such that 0.10 mm < Df < 0.50 mm, preferably 0.15 mm < Df < 0.50 mm and more preferably 0.15 mm < Df < 0.45 mm.

7. Reinforced product (R) according to any one of claims 2 to 6, wherein Dv is such that Dv > 0.40 mm, preferably 0.50 mm < Dv < 1.30 mm.

8. Reinforced product (R) according to any one of claims 2 to 7, in which each metallic reinforcing element (54) is wound at a pitch P such that 3 mm < P < 15 mm, preferably 5 mm < P < 13 mm and more preferably 7 mm < P < 11 mm,

9. Reinforced product (R) according to any one of the preceding claims, in which D < 2.10 mm, preferably 0.90 mm < D < 2.10 mm and more preferably 0.95 mm < D < 2.05 mm.

10. Reinforced product (R) according to any one of claims 1 to 9, wherein each metallic reinforcing element (54) of the cable (50) is a metallic wire (F) with N ranging from 3 to 18 and preferably from 4 to 15

11. 1 J. Reinforced product (R) according to any one of claims 1 to 9, wherein each metallic reinforcing element (54) of the cable (50') is a strand (T) with N ranging from 3 to 5, M ranging from 3 to 18 and preferably from 4 to 15.

12. Reinforced product (R) according to the preceding claim, in which the strands (T) define an internal arch (V) of the cable (50') of diameter Dvc, each strand (T) having a diameter D and a helix curvature radius Rt defined by Rt=Pe / (ir x Sin(2ae)) with Pe the pitch of each strand expressed in millimeters and ae the helix angle of each strand (T), Dvc, D and Rt being expressed in millimeters, the cable (50') satisfying the following relationships: 5 < Rt / D < 400 and 0.10 < Dvc / D< 0.

50.

13. Reinforced product (R) according to the preceding claim, in which the pitch of each strand Pe ranges from 20 mm to 120 mm.

14. Tire (P), characterized in that it comprises at least one reinforced product (R) according to any one of claims 1 to 13.

15. A tire (P) according to the preceding claim, comprising a crown (12) comprising a tread (20) and a crown reinforcement (14), two sidewalls (22), two beads (24), each sidewall (22) connecting each bead (24) to the crown (12), the crown reinforcement (14) extending in the crown (12) in a circumferential direction (Z) of the tire (P), the tire (P) comprising a carcass reinforcement (32) anchored in each of the beads (24) and extending in the sidewalls (22) and in the crown (12), the crown reinforcement (14) being radially interposed between the carcass reinforcement (32) and the tread (20), the crown reinforcement (14) comprising at least one reinforced product (R) according to any one of claims 1 to 13.

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