Compact cable with high mechanical strength comprising fine wires

Abstract

The subject of the invention is a cable comprising at least one strand (T) with at least two layers (C1, C3) comprising:- an inner layer (C1) consisting of Q inner metal wire(s) (F1) of diameter Df1, and- an outer layer (C3) consisting of N outer metal wires (F3) of diameter Df3 wound around the inner layer (C1), in which the diameter Df1, Df3 of each metal wire (F1; F3) ranges from 0.04 to 0.10 mm and in which each metal wire (F1; F3) has a breaking strength, denoted Rm, strictly greater than 3400 MPa determined by the ISO 6892-1 standard of October 2009. Figure for abstract: Fig.3

Description

Title of the invention: Compact cable with high mechanical strength comprising fine wires

[0001] The invention relates to a compact cable and a method for manufacturing this cable. The invention also relates to a reinforced product comprising this cable and a tire comprising this same cable.

[0002] In the tire sector, designers have long been looking for new cables that can advantageously and effectively replace conventional cables in order to achieve higher resistances with sufficient elongations.

[0003] Cables are known from the state of the art, and in particular from EP0976541, comprising a carbon steel core and an outer layer of stainless steel having a mechanical resistance of the metal wires ranging from 2700 to 3400 MPa.

[0004] Also known from the state of the art and in particular from JP02205220 are fishing lines made up of strands with fine metal wires covered with a corrosion-resistant layer and immersed in a low-viscosity resin.

[0005] The disadvantage of such cables is that the mechanical resistance obtained is too low for use in pneumatics.

[0006] The aim of the invention is to find a small diameter cable with high mechanical strength.

[0007] To this end, the invention relates to a cable comprising at least one strand with at least two layers comprising: - an internal layer consisting of Q internal metal wire(s) of diameter Dfl, and - an outer layer made up of N external metal wires of diameter Df3 wound around the inner layer, in which the diameter Dfl, Df3 of each metal wire ranges from 0.04 to 0.10 mm and in which each metal wire has a breaking strength, noted Rm, strictly greater than 3400 MPa determined by the ISO 6892-1 standard of October 2009.

[0008] The inventors behind the invention discovered that it was possible to assemble wires that were both very fine and very strong to obtain a compact cable of small diameter with high mechanical strength.

[0009] By constituted assembly, it is meant that the assembly does not include any elements other than the metal wires.

[0010] By “at least two layers” is meant that the inner strand may be, in certain embodiments, two-layered, i.e. it comprises only two layers but does not comprise only one, nor three; and that in other embodiments, the inner strand may be three-layer, that is, it comprises only three layers but does not comprise only two, nor four.

[0011] In one embodiment of the invention, the cable has two layers of wires, that is, it comprises an assembly consisting of two layers of wires, no more and no less, that is, the assembly has two layers of wires, not one, not three, but only two. The outer layer of the cable is wound around the inner layer of the cable in contact with the inner layer of the cable.

[0012] In another embodiment of the invention, the cable has three layers of wires, that is to say that it comprises an assembly consisting of three layers of wires, no more and no less, that is to say that the assembly has three layers of wires, not two, not four, but only three.

[0013] By wire 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.

[0014] By definition, the term "metal wire" 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 metal wire 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).

[0015] Preferably, each metal wire comprises from 0.50 to 0.86% carbon.

[0016] The breaking strength Rm is determined in mega Pascal (MPa), determined by the ISO 6892-1 standard of October 2009.

[0017] 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).

[0018] In the context of the invention, the carbon products mentioned in the description may be of fossil or bio-sourced origin. In the latter case, they may be, partially or totally, derived from biomass or obtained from renewable raw materials derived from biomass.

[0019] Within the framework of the invention, it may also be envisaged that the products Carbon elements mentioned in the description include isotopes of certain chemical elements.

[0020] Advantageously, the cable comprises several strands arranged in a single-layer arrangement.

[0021] In one embodiment, the cable comprises a single layer of several strands, that is to say it comprises an assembly consisting of one layer of strands, no more and no less, that is to say the assembly has one layer of strands, not zero, not two, but only one.

[0022] Preferably, the mechanical strength of the assembly, i.e. the mechanical strength of the cable denoted Rm ass, is greater than or equal to 2000 MPa and preferably greater than or equal to 2400 MPa.

[0023] Preferably, the diameter Dfl, Df3 of each metal wire ranges from 0.05 to 0.10 mm and preferably from 0.06 to 0.09 mm.

[0024] Preferably, in one embodiment, all the metallic wire elements have the same diameter Dfl=Df3.

[0025] Preferably, in another embodiment, the metallic wire elements have different diameters Dfl ^Df3.

[0026] Advantageously, the diameter of the cable ranges from 0.10 mm to 0.80 mm and preferably from 0.12 to 0.60 mm.

[0027] The diameter or apparent diameter, noted D, is measured by means of a thickness comparator whose probe diameter is at least equal to 1.5 times the wire winding pitch P (for example, the JD50 model from the KAEFER brand can be cited, allowing an accuracy of 1 / 100 of a millimeter to be achieved, equipped with a type a probe, 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.

[0028] Preferably, the number of strands ranges from 1 to 6 and preferably from 1 to 4.

[0029] In a first preferred embodiment, the or each strand T is two layers.

[0030] Advantageously, in this first mode, according to a first alternative, Q=1 and N=5 or 6, preferably Q=1 and N=6.

[0031] Advantageously, in this first mode, according to a second alternative, Q>1, preferably Q=2,3 or 4.

[0032] Preferably, in an embodiment of this second alternative, Q=2 and N=7 or 8, preferably Q=2 and N=7.

[0033] Preferably, in another embodiment of this second alternative, Q=3 and N= 7, 8 or 9, preferably Q=3 and N=8.

[0034] In a second preferred embodiment, the or each strand is three-layered and comprises: - an intermediate layer consisting of M intermediate metal wires wound around the inner layer, and - an outer layer made up of N external metal wires wound around the intermediate layer.

[0035] Advantageously, each metal wire is coated with a layer of zinc, copper, tin or an alloy of these metals. The steel is coated with a metal different from it. In particular, the metal wire is coated with a layer of zinc, copper, tin or an alloy of these metals, for example such as brass and bronze.

[0036] Brass-plated steel means that each metal wire is coated with a layer of a copper-zinc alloy.

[0037] By layer coating an object, it is meant that the layer or coating is in contact with the object without any other object, in particular another layer or coating, being interposed between the two.

[0038] Preferably, the total elongation at break At is greater than or equal to 2.0% determined by the ISO 6892-1 standard of October 2009.

[0039] The total elongation At, a quantity well known to those skilled in the art, is determined for example by applying the ISO 6892-1 standard of October 2009 to a cable tested so as to obtain a stress-elongation curve. The At is deduced on the curve obtained as the elongation, in %, corresponding to the projection on the elongation axis of the breaking point of the cable on the stress-elongation curve, that is to say the point at which the load increases up to a maximum stress value and then decreases abruptly after rupture. When the decrease in relation to the stress exceeds a certain threshold, this means that the cable has ruptured.

[0040] Advantageously, each metal wire has a breaking strength, noted Rm, greater than or equal to 3500 MPa and preferably greater than or equal to 3700 MPa.

[0041] Another object of the invention is a reinforced product comprising a cable as defined above.

[0042] Such reinforced products are pipes, belts, conveyor belts, tracks, tires for vehicles, both in the raw state (i.e. before crosslinking or vulcanization) and in the cured state (after crosslinking or vulcanization). Such reinforced products take, in preferred embodiments, the form of a sheet.

[0043] Finally, another subject of the invention is a tire comprising at least one cable as defined above or a reinforced product as defined above.

[0044] 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 cable as defined above.

[0045] In an advantageous embodiment, the hooping reinforcement comprises a single hooping ply. The hooping reinforcement is preferably constituted by a hooping ply comprising the cable according to the invention. This embodiment is particularly suitable for a tire for passenger vehicles, two-wheeled vehicles, industrial vehicles chosen from vans, "Heavy goods vehicles", for example metro, bus, road transport vehicles (trucks, tractors, trailers), and preferably for passenger vehicles.

[0046] In an advantageous embodiment, the hoop reinforcement is radially interposed between the working reinforcement and the tread. Thus, thanks to the use of metal cables, the hoop reinforcement performs, in addition to its hooping function, a much more effective protection function against perforations and impacts than a hoop reinforcement comprising textile hoop reinforcement wire elements.

[0047] In an advantageous embodiment, the or each wire reinforcement hoop element makes an angle strictly less than 10°, preferably less than or equal to 7° and more preferably less than or equal to 5° with the circumferential direction of the tire.

[0048] The invention will be better understood on 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 sectional view of a reinforced product (R) according to the invention; - [Fig.3] is a sectional view perpendicular to its axis of a cable (50) according to an embodiment of the invention (assumed to be rectilinear and at rest); - [Fig.4] is a sectional view perpendicular to its axis of a cable (60) according to another embodiment of the invention (assumed to be rectilinear and at rest); - [Fig.5] is a sectional view perpendicular to its axis of a cable (70) according to another embodiment of the invention (assumed to be rectilinear and at rest); - [Fig.6] is a sectional view perpendicular to its axis of a cable (80) according to another embodiment of the invention (assumed to be rectilinear and at rest); and - [Fig.7] is a photograph of a cable (50) according to one embodiment of the invention.

[0049] EXAMPLE OF A TIRE ACCORDING TO THE INVENTION

[0050] In [Fig. 1], a reference X, Y, Z is shown corresponding to the usual axial (X), radial (Y) and circumferential (Z) directions of a tire.

[0051] [Fig.l] schematically shows a radial sectional view of a tire according to the invention and designated by the general reference 10. The tire 10 is substantially of revolution around an axis substantially parallel to the axial direction X. The tire 10 is here intended for a passenger vehicle.

[0052] The tire 10 comprises a crown 12 comprising a crown reinforcement 14 comprising a working reinforcement 15 comprising two working plies 16, 18 respectively comprising working reinforcing wire elements and a hoop reinforcement 17 comprising a hoop ply 19 comprising at least one hoop reinforcement wire element. The crown reinforcement 14 extends in the crown 12 in the circumferential direction Z of the tire 10. The crown 12 comprises a tread 20 arranged radially outside the crown reinforcement 14. Here, the hoop reinforcement 17, here the hoop ply 19, is radially interposed between the working reinforcement 15 and the tread 20. Here, the working reinforcement 15 comprises only two working plies 16, 18 and the hoop reinforcement 17 comprises a single hoop ply 19.Here, the working reinforcement 15 is made up of the two working plies 16, 18 and the hoop reinforcement 17 is made up of the hoop reinforcement 19. The crown reinforcement 14 is made up of the working reinforcement 15 and the hoop reinforcement 17.

[0053] The tire 10 also comprises two sidewalls 22 extending the crown 12 radially inwards. The tire 10 further comprises two beads 24 radially inwards to the sidewalls 22 and each comprising an annular reinforcing structure 26, in this case a bead wire 28, surmounted by a mass of rubber 30 for filling the bead wire, as well as a radial carcass reinforcement 32. Each sidewall 22 connects each bead 24 to the crown 12.

[0054] The carcass reinforcement 32 comprises a carcass ply 34 comprising several carcass reinforcement wire elements, the carcass ply 34 being anchored to each of the beads 24 by a turn-up around the bead wire 28, so as to form in each bead 24 a forward strand 38 extending from the beads through the sidewalls towards the crown 12, and a return strand 40, the radially outer end 42 of the return strand 40 being radially outside the annular reinforcement structure 26. The carcass reinforcement 32 thus extends from the beads 24 into and through the sidewalls 22 into the crown 12. The carcass reinforcement 32 is arranged radially inside the crown reinforcement 14 and the hoop reinforcement 17. The crown reinforcement 14 is therefore radially interposed between the carcass reinforcement 32 and the tread 20. The carcass reinforcement 32 comprises a single carcass ply 34. Here, the carcass reinforcement 32 is made up of the carcass ply 34.

[0055] The tire 10 also comprises an internal sealing layer, preferably made of butyl, located axially inside the sidewalls 22 and radially inside the crown reinforcement 14 and extending between the two beads 24.

[0056] Each working ply 16, 18, hooping ply 19 and carcass ply 34 comprises an elastomeric matrix in which reinforcing elements of the corresponding ply are embedded. Each elastomeric matrix of the working ply 16, 18, hooping ply 19 and carcass ply 34 is based on a conventional elastomeric composition for calendering reinforcing elements conventionally comprising 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.

[0057] Here the hooping sheet 19 comprises at least one reinforcing element 50 as described below.

[0058] EXAMPLE OF REINFORCED PRODUCT ACCORDING TO THE INVENTION

[0059] [Fig. 2] shows a reinforced product according to the invention and designated by the general reference R. The reinforced product R comprises at least one reinforcing element 50, in this case several reinforcing elements 50, embedded in the polymer matrix Ma.

[0060] In [Fig. 2], the polymer matrix Ma is represented, the reinforcing elements 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. 2], the reinforced product R comprises several reinforcing elements 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.

[0061] Here, the polymer matrix Ma is an elastomeric matrix based on an elastomeric composition.

[0062] METHOD FOR MANUFACTURING THE REINFORCING ELEMENT ACCORDING TO THE INVENTION

[0063] In a cable manufacturing step using the following steps, preferably carried out in line and continuously: - a first assembly step by twisting the Q = 3 internal threads Fl of the internal layer Cl at the pitch pl and in the direction S to form the internal layer Cl at a first assembly point; - followed by a second assembly step by twisting the N= 8 external threads F3 around the 3 internal threads Fl of the internal layer Cl at pitch p3 and in the direction S to form the external layer C3 at a second assembly point; - preferably a final torsion balancing step.

[0064] This cable can be produced in one step on a twisting machine with rotating feed and fixed reception or in two steps on a machine with fixed feed and rotating reception.

[0065] For example, on the rotating power supply, the layer C1 of three wires is first assembled at a pitch pl of 4 mm to be surrounded at a pitch p3 of 8 mm with the eight wires to form the layer C3.

[0066] EXAMPLE OF A REINFORCING ELEMENT ACCORDING TO THE INVENTION

[0067] [Fig. 3] shows the reinforcing element 50 according to one embodiment of the invention.

[0068] [Fig.7] represents a photograph of the reinforcing element 50 in the polymer matrix.

[0069] The reinforcing element 50 comprises an assembly consisting of a two-layer strand T C1, C3 comprising: - an internal layer Cl consisting of Q= 3 internal metal wires Fl with a diameter Dfl= 0.09mm, and - an external layer C3 consisting of N = 8 external metal wires F3 of diameter Df3 = 0.09 mm wound around the internal layer Cl, in which the diameter Dfl, Df3 of each metal wire Fl; F3 is 0.09 mm and in which each metal wire Fl; F3 has a breaking strength, noted Rm = 4495 MPa and an Rm for the assembly of 4196 MPa.

[0070] Table 1 below summarizes the characteristics for the different cables 50, 60, 70 and 80 according to several embodiments of the invention, which are represented respectively in Figures 3 to 6 and that of the wire of the state of the art EDT of application EP0976541. The term NC means that there is no data in the patent application.

[0071] The term Rm ass designates the mechanical resistance of the cable.

[0072] [Tables 1] Cable EDT 50 50' 60 70 80 T / pitch (mm) - - - - - 3 Number of T - 1 1 1 1 3 Q / N - 3 / 8 3 / 8 2 / 7 1 / 6 1 / 6 Dfl / Df3 (mm) 0.20 0.09 / 0.09 0.06 / 0.06 0.06 / 0.06 0.09 / 0.06 0.09 / 0.06 pl / p3 (mm) - 4 / 8 1.8 / 3.5 2.6 / 5.2 Inf / 3.2 Inf / 3.2 Rm wire (MPa) 2850 4495 4138 3723 0.09 : 3723 0.06 : 4000 0.09 : 3723 0.06 : 4000 Rm ass (MPa) 4196 3756 3402 3176 2432 Cable diameter (mm) - 0.37 0.25 0.36 0.21 0.50 At (%) NC 2.63 2.73 2.45 2.45 3.50 As (%) 0.036 0.28 0.11 0.50 1.40

[0073] It can be seen that the cables 50, 50', 60, 70 and 80 according to the invention make it possible to obtain a small diameter cable with high mechanical strength for the wires as well as for the cable assembled with these same wires.

[0074] The invention is not limited to the embodiments previously described.

[0075] For the manufacturing process of the reinforcing element, it is also possible to assemble the metal wire elements together by wiring to form the internal layer, then assemble the metal wire elements around the internal layer by wiring to form a strand and then, in a second step, assemble the strands by wiring to form the reinforcing element.

Claims

Claims

1. Cable (50), characterized in that it comprises at least one strand (T) with at least two layers (Cl, C3) comprising: - an inner layer (Cl) consisting of Q inner metal wire(s) (Fl) of diameter Dfl, and - an outer layer (C3) consisting of N outer metal wires (F3) of diameter Df3 wound around the inner layer (Cl), in which the diameter Dfl, Df3 of each metal wire (Fl; F3) ranges from 0.04 to 0.10 mm and in which each metal wire (Fl; F3) has a breaking strength, noted Rm, strictly greater than 3400 MPa determined by the ISO 6892-1 standard of October 2009.

2. Cable (50) according to the preceding claim, comprising several strands (T) arranged in a single-layer arrangement.

3. Cable (50) according to any one of the preceding claims, wherein the diameter Dfl, Df3 of each metal wire (Fl; F3) ranges from 0.05 to 0.10 mm and preferably from 0.06 to 0.09 mm.

4. Cable (50) according to any one of the preceding claims, wherein the diameter of the cable (50) ranges from 0.10 mm to 0.80 mm and preferably from 0.12 to 0.60 mm.

5. Cable (50) according to any one of the preceding claims, wherein the number of strands (T) ranges from 1 to 6 and preferably from 1 to 4.

6. Cable (50) according to any one of claims 1 to 5, wherein the or each strand (T) is two-layer (C1, C3).

7. Cable (50) according to any one of claims 1 to 6, wherein Q= 1 and N=5 or 6, preferably Q= 1 and N=6.

8. Cable (50) according to any one of claims 1 to 6, wherein Q>1, preferably Q=2, 3 or 4.

9. Cable (50) according to claim 8, wherein Q=2 and N=7 or 8, preferably Q=2 and N=7.

10. Cable (50) according to claim 8, wherein Q=3 and N=7, 8 or 9, preferably Q=3 and N=8.

11. Cable (50) according to any one of the preceding claims, in which each metal wire (F1; F3) is coated with a layer of zinc, copper, tin or an alloy of these metals.

12. Cable (50) according to any one of the preceding claims, wherein the total elongation at break At is greater than or equal to 2.0% determined by ISO 6892-1 of October 2009.

13. Cable (50) according to any one of the preceding claims, in which each metal wire has a breaking strength, denoted Rm, greater than or equal to 3500 MPa and preferably greater than or equal to 3700 MPa.

14. Reinforced product (R) comprising a cable (50) according to any one of claims 1 to 13.

15. A tire comprising at least one cable (50) according to any one of claims 1 to 13 or a reinforced product (R) according to claim 14.

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