PROCESS AND APPARATUS FOR MANUFACTURING A METALLIC REINFORCING CORD FOR TYRES FOR VEHICLE WHEELS

Abstract

The invention relates to a process for manufacturing a metallic reinforcing cord (10) for tyres for vehicle wheels. The process comprises providing at least one elongated element (15) comprising at least one metallic wire (11) twisted together with at least one textile yarn (20) and removing said at least one textile yarn (20) from said at least one elongated element (15) to form the aforementioned metallic reinforcing cord (10). Such a metallic reinforcing cord (10) has a helical geometry, consisting only of said at least one metallic wire (11) that extends along a helical path. The invention also relates to an apparatus (1) for manufacturing the aforementioned metallic reinforcing cord (10).

Claims

1. Process for manufacturing a metallic reinforcing cord for tyres for vehicle wheels, comprising: providing at least one elongated element (15) comprising at least one metallic wire (11) twisted together with at least one textile yarn (20); removing said at least one textile yarn (20) from said at least one elongated element (15) to form a metallic reinforcing cord (10) in which said at least one metallic wire (11) extends along a helical path.

2. Process according to claim 1, wherein providing said at least one elongated element (15) comprises: feeding said at least one metallic wire (11) and said at least one textile yarn (20) to a twisting device (60); twisting together said at least one metallic wire (11) and said at least one textile yarn (20) in said twisting device (60) thus obtaining said at least one elongated element (15).

3. Process according to claim 2, comprising, before removing said at least one textile yarn (20) from said at least one elongated element (15): winding said at least one elongated element (15) on a respective service reel (45).

4. Process according to claim 2, wherein removal of said at least one textile yarn (20) is carried out while obtaining said at least one elongated element (15).

5. Process according to any one of the previous claims, wherein said at least one textile yarn (20) is made of a water-soluble material.

6. Process according to claim 5 when depending on claim 4, wherein removing said at least one textile yarn (20) comprises feeding a hot water jet against said at least one elongated element (15).

7. Process according to claim 5 or 6, comprising, after removing said at least one textile yarn (20): drying said metallic reinforcing cord (10); winding said metallic reinforcing cord (10) on a collection reel (50).

8. Process according to any one of the previous claims, wherein said at least one elongated element (15) comprises at least two metallic wires (11) twisted together with said at least one textile yarn (20).

9. Process according to claim 8, wherein said metallic reinforcing cord (10) comprises a plurality of cross sections in which said at least two metallic wires (11) are in a condition of substantial mutual contact.

10. Process according to claim 9, comprising: deforming said metallic reinforcing cord (10) so that in all of the cross sections thereof said at least two metallic wires (11) are spaced apart from each other.

11. Process according to claim 10, wherein deforming said metallic reinforcing cord (10) comprises pulling said metallic reinforcing cord (10) by a traction force that is constant or variable over time.

12. Apparatus (1) for manufacturing a metallic reinforcing cord for tyres (100) for vehicle wheels from at least one elongated element (15) comprising at least one metallic wire (11) twisted together with at least one textile yarn (20), the apparatus (1) comprising a removal device (70) configured to remove said at least one textile yarn (20) from said at least one elongated element (15) to form a metallic reinforcing cord (10) in which said at least one metallic wire (11) extends along a helical path.

13. Apparatus (1) according to claim 12, comprising, upstream of said removal device (70) with respect to a feeding direction (A) of said at least one elongated element (15), at least one service reel (45) configured to collect said at least one elongated element (15).

14. Apparatus (1) according to claim 12, comprising, upstream of said removal device (70) with respect to said feeding direction (A), a twisting device (60) configured to twist together said at least one metallic wire (11) and said at least one textile yarn (20) thus obtaining said at least one elongated element (15).

15. Apparatus (1) according to any one of claims 12 to 14, comprising, downstream of said removal device (70) with respect to said feeding direction (A), a collecting reel (50) configured to collect said metallic reinforcing cord (10).

16. Apparatus (1) according to any one of claims 12 to 15, wherein said removal device (70) comprises at least one hot water jet feeding device (73).

17. Apparatus (1) according to claim 16, comprising a drying device (75) arranged downstream of said hot water jet feeding device (73) with respect to said feeding direction (A).

Description

DESCRIPTION OF THE FIGURES

[0113] Further features and advantages of the present invention will become clearer from the following detailed description of a preferred embodiment thereof, made with reference to the attached drawings.

[0114] In such drawings:

[0115] FIG. 1 is a schematic partial half cross-section view of a portion of a possible embodiment of a tyre in which a metallic reinforcing cord in accordance with the present invention can be used;

[0116] FIG. 2 is a photo of a segment of a first embodiment of a metallic reinforcing cord in accordance with the present invention;

[0117] FIG. 3 is a photo of a textile yarn used to manufacture the metallic reinforcing cord of FIG. 2;

[0118] FIG. 3a is a photo of an elongated element used to manufacture the metallic reinforcing cord of FIG. 2 through the textile yarn of FIG. 3;

[0119] FIG. 4 is a schematic view of a first embodiment of an apparatus for manufacturing the metallic reinforcing cord in accordance with the present invention, such an apparatus carrying out a continuous process;

[0120] FIGS. 5a and 5b show a second embodiment of an apparatus for manufacturing the metallic reinforcing cord in accordance with the present invention, such an apparatus carrying out a discontinuous process;

[0121] FIGS. 6-10 show some load-elongation graphs of conventional cords and of metallic reinforcing cords made in accordance with the present invention;

[0122] FIGS. 11-20 show various examples of metallic reinforcing cords made in accordance with the present invention and of conventional metallic reinforcing cords; some cross sections of each of the aforementioned reinforcing cords in a respective piece of elastomeric material are also illustrated;

[0123] FIGS. 21 and 22 show respective segments of further embodiments of metallic reinforcing cords made in accordance with the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0124] For the sake of simplicity, FIG. 1 shows only part of an embodiment of a tyre 100 produced with the method and the apparatus of the present invention, the remaining part, which is not shown, being substantially identical and being arranged symmetrically with respect to the equatorial plane M-M of the tyre.

[0125] The tyre 100 shown in FIG. 1 is, in particular, a tyre for four-wheeled vehicles.

[0126] Preferably, the tyre 100 is a HP or UHP tyre for sports and/or high or ultra-high-performance automobiles.

[0127] In FIG. 1 “a” indicates an axial direction, “c” indicates a radial direction, “M-M” indicates the equatorial plane of the tyre 100 and “R-R” indicates the rotation axis of the tyre 100.

[0128] The tyre 100 comprises at least one support structure 100a and, in a radially outer position with respect to the support structure 100a, a tread band 109 made of elastomeric material.

[0129] The support structure 100a comprises a carcass structure 101, which comprises at least one carcass layer 111.

[0130] Hereinafter, for the sake of simplicity of description, reference will be made to an embodiment of the tyre 100 comprising a single carcass layer 111, being nevertheless understood that what is described has analogous application in tyres comprising more than one carcass layer.

[0131] The carcass layer 111 has axially opposite end edges engaged with respective annular anchoring structures 102, called bead cores, possibly associated with an elastomeric filler 104. The zone of the tyre 100 comprising the bead core 102 and the possible elastomeric filler 104 forms an annular reinforcing structure 103 called “bead structure” and intended to allow the anchoring of the tyre 100 on a corresponding mounting rim, not shown.

[0132] The carcass layer 111 comprises a plurality of reinforcing cords 10′ coated with an elastomeric material or incorporated in a matrix of cross-linked elastomeric material.

[0133] The carcass structure 101 is of the radial type, i.e. the reinforcing cords 10′ are on planes comprising the rotation axis R-R of the tyre 100 and substantially perpendicular to the equatorial plane M-M of the tyre 100.

[0134] Each annular reinforcing structure 103 is associated with the carcass structure 101 by folding back (or turning) the opposite end edges of the at least one carcass layer 111 about the bead core 102 and the possible elastomeric filler 104, so as to form the so-called turnings 101a of the carcass structure 101.

[0135] In an embodiment, the coupling between carcass structure 101 and annular reinforcing structure 103 can be made through a second carcass layer (not shown in FIG. 1) which is applied in a radially outer position with respect to the carcass layer 111.

[0136] An anti-abrasion strip 105 is arranged at each annular reinforcing structure 103 so as to wrap around the annular reinforcing structure 103 along the axially inner, axially outer and radially inner zones of the annular reinforcing structure 103, thus being arranged between the latter and the rim of the wheel when the tyre 100 is mounted on the rim. However, embodiments wherein such an anti-abrasion strip 105 is not provided are foreseen.

[0137] The support structure 100a comprises, in a radially outer position with respect to the carcass structure 101, a crossed belt structure 106 comprising at least two belt layers 106a, 106b arranged in radial juxtaposition with respect to one another.

[0138] The belt layers 106a, 106b respectively comprise a plurality of reinforcing cords 10a, 10b. Such reinforcing cords 10a, 10b have an inclined orientation with respect to the circumferential direction of the tyre 100, or to the equatorial plane M-M of the tyre 100, by an angle comprised between 15° and 45°, preferably between 20° and 40°. For example, such an angle is equal to 30°.

[0139] The support structure 100a can also comprise a further belt layer (not shown) arranged between the carcass structure 101 and the radially inner belt layer of the aforementioned belt layers 106a, 106b and comprising a plurality of reinforcing cords having an inclined orientation with respect to the circumferential direction of the tyre 100, or to the equatorial plane M-M of the tyre 100, by an angle equal to 90°.

[0140] The support structure 100a can also comprise a further belt layer (not shown) arranged in a radially outer position with respect to the radially outer belt layer of the aforementioned belt layers 106a, 106b and comprising a plurality of reinforcing cords having an inclined orientation with respect to the circumferential direction of the tyre 100, or to the equatorial plane M-M of the tyre 100, by an angle comprised between 200 and 700.

[0141] The reinforcing cords 10a, 10b of a belt layer 106a, 106b are parallel to one another and have a crossed orientation with respect to the reinforcing cords of the other belt layer 106b, 106a.

[0142] In ultra-high-performance tyres, the belt structure 106 can be a turned crossed belt structure. Such a belt structure is made by arranging at least one belt layer on a support element and turning the opposite lateral end edges of said at least one belt layer. Preferably, a first belt layer is initially deposited on the support element, then the support element radially expands, then a second belt layer is deposited on the first belt layer and finally the opposite axial end edges of the first belt layer are turned on the second belt layer to at least partially cover the second belt layer, which is the radially outermost layer. In some cases, it is possible to deposit a third belt layer on the second belt layer. Advantageously, the turning of the axially opposite end edges of a belt layer on a radially outer belt layer imparts greater reactivity and responsiveness of the tyre when entering a bend.

[0143] The support structure 100a comprises, in a radially outer position with respect to the crossed belt structure 106, at least one zero degrees belt layer 106c, commonly known as “zero degrees belt”. It comprises reinforcing cords 10c oriented along a substantially circumferential direction. Such reinforcing cords 10c thus form an angle of a few degrees (typically lower than 10°, for example comprised between 0° and 6°) with respect to the equatorial plane M-M of the tyre 100.

[0144] The tread band 109 is applied in a radially outer position with respect to the zero degrees belt layer 106c, like other semi-finished products which constitute the tyre 100.

[0145] Respective sidewalls 108 made of elastomeric material are also applied on the opposite lateral surfaces of the carcass structure 101, in an axially outer position with respect to the carcass structure 101 itself. Each sidewall 108 extends from one of the lateral edges of the tread band 109 up to the respective annular reinforcing structure 103.

[0146] The anti-abrasion strip 105, when provided, extends at least up to the respective sidewall 108.

[0147] In some specific embodiments, like the one shown and described herein, the rigidity of the sidewall 108 can be improved by providing a stiffening layer 120, generally known as “flipper” or additional strip-like insert, which has the function of increasing the rigidity and integrity of the annular reinforcing structure 103 and of the sidewall 108.

[0148] The flipper 120 is wound around a respective bead core 102 and the elastomeric filler 104 so as to at least partially surround the annular reinforcing structure 103. In particular, the flipper 120 wraps around the annular reinforcing structure 103 along the axially inner, axially outer and radially inner zones of the annular reinforcing structure 103.

[0149] The flipper 120 is arranged between the turned end edge of the carcass layer 111 and the respective annular reinforcing structure 103. Usually, the flipper 120 is in contact with the carcass layer 111 and the annular reinforcing structure 103.

[0150] In some specific embodiments, like the one shown and described herein, the bead structure 103 can also comprise a further stiffening layer 121 that is generally known with the term “chafer”, or protective strip, and which has the function of increasing the rigidity and integrity of the annular reinforcing structure 103.

[0151] The chafer 121 is associated with a respective turned end edge of the carcass layer 111 in an axially outer position with respect to the respective annular reinforcing structure 103 and extends radially towards the sidewall 108 and the tread band 109.

[0152] The flipper 120 and the chafer 121 comprise reinforcing cords 10d (in the attached figures those of the chafer 121 cannot be seen) coated with an elastomeric material or incorporated in a matrix of cross-linked elastomeric material.

[0153] The tread band 109 has, in a radially outer position thereof, a rolling surface 109a intended to come into contact with the ground. The rolling surface 109a has circumferential grooves (not shown in FIG. 1) formed on it, which are connected by transversal notches (not shown in FIG. 1) so as to define a plurality of blocks of various shapes and sizes (not shown in FIG. 1) on the rolling surface 109a.

[0154] A sub-layer 107 is arranged between the zero degrees belt layer 106c and the tread band 109.

[0155] In some specific embodiments, like the one shown and described herein, a strip 110 consisting of elastomeric material, commonly known as “mini-sidewall”, can possibly be provided in the connection zone between the sidewalls 108 and the tread band 109. The mini-sidewall 110 is generally obtained through co-extrusion with the tread band 109 and allows an improvement of the mechanical interaction between the tread band 109 and the sidewalls 108.

[0156] Preferably, an end portion of the sidewall 108 directly covers the lateral edge of the tread band 109.

[0157] In the case of tyres without an air chamber, a layer of elastomeric material 112, generally known as “liner”, can also be provided in a radially inner position with respect to the carcass layer 111 to provide the necessary impermeability to the inflation air of the tyre 100.

[0158] Depending on the type of tyre 100, the reinforcing cords 10a, 10b, 10c, 10d can be metallic reinforcing cords 10 made in accordance with the present invention. Such metallic reinforcing cords 10 can also be used in the carcass structure or belt structure of tyres for motorcycle wheels and in the stoneguard layer and/or in the carcass layer or belt layer of tyres for heavy and/or light load vehicle wheels.

[0159] An embodiment of a metallic reinforcing cord 10 made in accordance with the present invention is shown in FIG. 2.

[0160] With reference to such a figure, the metallic reinforcing cord 10 comprises a plurality of metallic wires 11 (four in the illustrated example) each extending along a longitudinal direction L according to a helical geometry defined by a respective helix having a predetermined winding pitch P. The metallic reinforcing cord 10 thus extends longitudinally along a helical path with the aforementioned predetermined winding pitch P.

[0161] With reference to FIGS. 3 and 3a, the metallic reinforcing cord 10 of FIG. 2 is obtained by twisting together, in a conventional twisting machine (not shown in the figures), said plurality of wires 11 and a textile yarn 20 (for example of the type shown in FIG. 3) with a twisting pitch equal to the aforementioned winding pitch P, to make an elongated element 15 (for example of the type illustrated in FIG. 3a).

[0162] As will be described hereinafter with reference to FIGS. 4 and 5a, 5b, the textile yarn 20 is intended to be removed from the elongated element 15. After such removal, the metallic wires 11 keep the aforementioned helical geometry and define the metallic reinforcing cord 10, which will also have a helical geometry.

[0163] The metallic wires 11 are preferably all made of the same material, more preferably all made of steel. The metallic wires 11 can be wires made of NT (Normal Tensile) steel or wires made of HT (High Tensile) steel or wires made of ST (Super Tensile) steel or wires made of UT (Ultra Tensile) steel.

[0164] The metallic wires 11 have a carbon content lower than or equal to 1, preferably lower than or equal to 0.9%.

[0165] Preferably, the carbon content is greater than or equal to 0.7%.

[0166] In preferred embodiments, the carbon content is comprised between 0.7% and 1%, preferably between 0.7% and 0.9%.

[0167] The metallic wires 11 are typically coated with brass or another corrosion-resistant coating (for example Zn/Mn).

[0168] The metallic wires 11 have a diameter preferably greater than, or equal to, 0.04 mm, more preferably greater than, or equal to, 0.08 mm, even more preferably lower than, or equal to, 0.10 mm.

[0169] The metallic wires 11 have a diameter preferably lower than, or equal to 0.60 mm, more preferably lower than, or equal to, 0.45 mm.

[0170] In preferred embodiments, the metallic wires 11 have a diameter comprised between 0.04 mm and 0.60 mm, preferably between 0.08 mm and 0.45 mm, even more preferably between 0.10 mm and 0.45 mm.

[0171] For example, the metallic wires 11 have a diameter equal to: 0.10 mm, or 0.12 mm, or 0.13 mm, or 0.15 mm, or 0.175 mm, or 0.20 mm, or 0.22 mm, or 0.245 mm, or 0.25 mm, or 0.265 mm, or 0.27 mm, or 0.28 mm, or 0.30 mm, or 0.32 mm, or 0.35 mm, or 0.38 mm, or 0.40 mm, or 0.42 mm, or 0.45 mm.

[0172] The number of metallic wires 11 is preferably comprised between 1 and 27.

[0173] The textile yarn 20 is preferably made of a water-soluble synthetic polymeric material, even more preferably a polyvinyl alcohol (PVA). Such a textile yarn 20 can be purchased from specialized producers, like for example Kuraray Co., Ltd or Sekisui Specialty Chemicals, or be made by twisting together a plurality of PVA filaments in a conventional twisting machine.

[0174] The textile yarn 20 has a diameter preferably greater than, or equal to, 0.15 mm, more preferably greater than, or equal to, 0.30 mm.

[0175] The textile yarn 20 has a diameter preferably lower than, or equal to, 2 mm, more preferably lower than, or equal to, 1 mm.

[0176] In preferred embodiments, the textile yarn 20 has a diameter comprised between 0.15 mm and 2 mm, preferably between 0.30 mm and 1 mm.

[0177] The textile yarn 20 has a linear density preferably greater than, or equal to, 200 dtex, more preferably greater than, or equal to, 700 dtex.

[0178] The textile yarn 20 has a linear density preferably lower than, or equal to, 4400 dtex, more preferably lower than, or equal to, 1670 dtex.

[0179] In preferred embodiments, the textile yarn 20 has a linear density comprised between 200 dtex and 4400 dtex, preferably between 700 dtex and 1670 dtex.

[0180] The metallic reinforcing cord 10 can also comprise a single metallic wire 11.

[0181] The elongated element 15 can comprise more than one textile yarn 20.

[0182] Each metallic wire 11 can be twisted on itself, in the same direction as, or in the opposite direction to, the direction in which it is twisted on the textile yarn 20.

[0183] The winding pitch P of the metallic wires 11 is preferably greater than, or equal to, 2 mm, more preferably greater than, or equal to, 4 mm.

[0184] The winding pitch P of the metallic wires 11 is preferably lower than, or equal to, 50 mm, more preferably lower than, or equal to, 25 mm.

[0185] In preferred embodiments, the winding pitch P of the metallic wires 11 is comprised between 2 mm and 50 mm, preferably between 4 mm and 25 mm.

[0186] The arrangement of the metallic wires 11 about the textile yarn 20 is such that the metallic wires 11 do not completely wrap around the textile yarn 20. In particular, the metallic wires 11 are arranged around the textile yarn 20 so that, in any cross section of the elongated element 15, they are at only an angular portion of an ideal circumference that circumscribes the textile yarn 20. Such an angular portion is defined by an angle that is preferably greater than, or equal to, 15°, more preferably greater than, or equal to, 20°.

[0187] Preferably, such an angle is lower than, or equal to, 45°, more preferably lower than, or equal to, 30°.

[0188] In preferred embodiments such an angle is comprised between 15° and 45°, more preferably between 20° and 30°.

[0189] The metallic reinforcing cord 10 can be obtained from a plurality of elongated elements 15 twisted together.

[0190] The metallic wires 11 can be twisted together with the textile yarn 20 with the aforementioned twisting pitch P to form metallic reinforcing cords 10 having a construction of the n×D type, where n is the number of metallic wires 11 and D is the diameter of the metallic wires 11.

[0191] Examples of metallic reinforcing cords 10 having a construction of the n×D type are shown in FIGS. 2, 12, 13, 15, 16, 17 and 20.

[0192] The metallic reinforcing cord 10 of FIG. 2 has a 4×D construction, whereas the construction of the reinforcing cords of FIGS. 12, 13, 15, 16, 17 and 20 is indicated in the aforementioned figures.

[0193] Preferably, in the metallic reinforcing cords 10 having a construction of the n×D type, the number of metallic wires 11 is comprised between 2 and 7, more preferably between 2 and 6, even more preferably between 2 and 5. Preferably, all of the metallic wires 11 have the same diameter.

[0194] Alternatively, the metallic wires 11 can be twisted together with the aforementioned twisting pitch P to form respective metallic strands 11 that are then twisted together to form the metallic reinforcing cord 10.

[0195] Examples of such metallic reinforcing cords 10 are shown in FIGS. 11, 14, 18 and 19. Such metallic reinforcing cords 10 have a construction of the m×n×D type, where m is the number of strands twisted together, n is the number of metallic wires of the respective strand and D is the diameter of the latter. The construction of the reinforcing cords of FIGS. 11, 14, 18 and 19 is indicated in the aforementioned figures.

[0196] In the metallic reinforcing cords 10 having a construction of the m×n×D type, the number of strands of metallic wires 11 can be equal to or different from the number of metallic wires of each strand of metallic wires 11.

[0197] Preferably, the number of strands of metallic wires 11 is comprised between 3 and 6, more preferably between 2 and 5.

[0198] Preferably, the number of metallic wires 11 of each strand of metallic wires 11 is comprised between 2 and 7.

[0199] The twisting pitch of the metallic wires of a strand of metallic wires 11 can be equal to or different from that of the metallic wires of another strand of metallic wires 11 and equal to or different from the twisting pitch of the various strands of metallic wires 11.

[0200] Preferably, all of the metallic wires of all of the strands of metallic wires 11 have the same diameter, but embodiments are foreseen wherein the metallic wires of a strand of metallic wires 11 have the same diameter, such a diameter being different that of the metallic wires of another strand of metallic wires 11.

[0201] Alternatively, the metallic wires 11 can be twisted together so as to take up a geometry like that shown in FIG. 21, or a different geometry like that shown in FIG. 22.

[0202] In the embodiment of FIG. 21, the metallic reinforcing cord 10 comprises a substantially straight first metallic wire 11a on which a second metallic wire 11b is wound in a helix with the aforementioned twisting pitch P. The metallic reinforcing cord of FIG. 21 therefore has a 1+1×D construction, where D is the diameter of the metallic wires 11a and 11b.

[0203] Preferably, in the metallic reinforcing cords having a 1+1×D construction, the metallic wires 11a and 11b have the same diameter, but embodiments are foreseen wherein the metallic wires 11a and 11b have different diameters.

[0204] Further embodiments are foreseen comprising a plurality of substantially parallel metallic wires 11a and a metallic wire 11b wound in a helix on such metallic wires 11a. Such metallic reinforcing cords 10 have a construction of the 1+n×D type, where n is the number of metallic wires 11a and D is the diameter of the metallic wires 11a and 11b.

[0205] Preferably, in the metallic reinforcing cords 10 having a construction of the 1+n×D type the number of metallic wires 11a is comprised between 2 and 7, more preferably between 2 and 6.

[0206] Preferably, the metallic wires 11a have the same diameter, but embodiments are foreseen wherein the metallic wires 11a and 11b have different diameters.

[0207] Alternatively, it is possible to provide metallic reinforcing cords 10 comprising a single substantially straight metallic wire 11a and a plurality of metallic wires 11b wound in a helix on the aforementioned metallic wire 11a. Such metallic reinforcing cords 10 have a construction of the n×1×D type, where n is the number of metallic wires 11b and D is the diameter of the metallic wires 11a and 11b.

[0208] Preferably, in the metallic reinforcing cords 10 having a construction of the n×1×D type the number of metallic wires 11b is comprised between 2 and 7, more preferably between 2 and 6.

[0209] Preferably, the metallic wires 11b have the same diameter, but embodiments are foreseen wherein the metallic wires 11a and 11b have different diameters.

[0210] In the embodiment of FIG. 22, the metallic reinforcing cord 10 comprises at least two metallic wires 11a, 11b twisted together with the aforementioned twisting pitch to define at least one strand of metallic wires 11. The strand of metallic wires 11 is twisted together with a plurality of metallic wires 12 (in the case shown in FIG. 12, three metallic wires 12) with a twisting pitch P1 that can be equal to or different from the twisting pitch P (in the specific example shown in FIG. 22, P1 is different from P). Such a metallic reinforcing cord 10 has a construction of the m+n×D type, where m is the number of strands of metallic wires 11, n is the number of metallic wires and D is the diameter of the metallic wires 11a and 11b.

[0211] The metallic reinforcing cord of FIG. 22 has a construction 1+3×D.

[0212] The number of metallic wires of each strand of metallic wires 11 can be equal to or different from the number of strands of metallic wires 11 and from the number of metallic wires 12.

[0213] Preferably, the number of metallic wires of each strand of metallic wires 11 is comprised between 1 and 7.

[0214] Preferably, the number of strands of metallic wires 11 is comprised between 1 and 7, more preferably between 1 and 6, even more preferably between 1 and 4.

[0215] Preferably, the number of metallic wires 12 is comprised between 2 and 7.

[0216] Preferably, the metallic wires 11a, 11b and 12 all have the same diameter, but embodiments are foreseen wherein the metallic wires 12 have a diameter different from that of the metallic wires 11a, 11b.

[0217] With reference to FIG. 4, an embodiment of an apparatus for manufacturing the metallic reinforcing cord 10 in accordance with the present invention and an embodiment of a process for manufacturing the metallic reinforcing cord 10 in accordance with the present invention are described. For the sake of simplicity of description, reference will be made to a metallic reinforcing cord 10 consisting of a single metallic wire 11, obtained from a single elongated element 15, the latter being obtained by twisting together said single metallic wire 11 and a single textile yarn 20.

[0218] The textile yarn 20 and the metallic wire 11 are taken from respective reels 40 and 30 and fed to a twisting device 60 to be twisted together, so as to form the elongated element 15. The twisting device 60 is therefore arranged downstream of the reels 40 and 30 with respect to a feeding direction indicated with A in FIG. 4.

[0219] The elongated element 15 is fed, along said feeding direction A, to a removal device 70 in which the textile yarn 20 is removed from the elongated element 15, thus obtaining the metallic reinforcing cord 10. The removal device 70 is therefore arranged downstream of the twisting device 60 with respect to the feeding direction A.

[0220] In a preferred embodiment of the invention, the removal device 70 comprises a hot water jet feeding device 73 configured to feed a hot water jet against the elongated element 15, in a counter-current while the elongated element 15 moves along the feeding direction A. The hot water jet dissolves the textile yarn 20 while such a jet is crossed by the metallic wire 11, which remains the only constituent element of the metallic reinforcing cord 10.

[0221] Preferably, the metallic reinforcing cord 10 thus formed then crosses a drying device 75 to be subsequently wound in a respective collection reel 50, from which it can be taken during the manufacture of the specific structural component of the tyre 100 of interest. The drying device 75 is therefore arranged downstream of the removal device 70 with respect to the feeding direction A.

[0222] In the process described above with reference to FIG. 4, the manufacturing of the metallic reinforcing cord 10 is carried out while obtaining the elongated element 15 (and while removing the textile yarn 20). The metallic reinforcing cord 10 is thus made through a continuous process that comprises, in a time sequence free of interruptions or stops, making the elongated element 15 by mutually twisting the metallic wire 11 and the textile yarn 20, moving the elongated element 15 thus made along the feeding direction A, removing the textile yarn 20, possibly drying the metallic reinforcing cord 10 thus formed and winding the metallic reinforcing cord 10 in the collection reel 50.

[0223] However, it is possible to manufacture the metallic reinforcing cord 10 in two distinct operative steps, i.e. through a discontinuous process like for example the one shown in FIGS. 5a, 5b. Such a process differs from the one described above with reference to FIG. 4 only in that the elongated element 15, once made, is collected in a service reel 45 (FIG. 5a), from which it can be taken when desired to proceed with the manufacturing of the metallic reinforcing cord 10 as described earlier (FIG. 5b). The service reel 45 is thus intended to be arranged downstream of the twisting device 60 when the elongated element 15 is made and upstream of the removal device 70 when the textile yarn 20 is removed from the elongated element 15 to manufacture the metallic reinforcing cord 10.

[0224] The metallic reinforcing cords 10 are intended to be incorporated in a piece of elastomeric material through conventional calendering processes in conventional rubberizing machines to make the various structural components of the tyre 100 described above.

[0225] The metallic reinforcing cord 10 can be made with different helical geometries depending on the particular application (type of tyre of interest or structural component thereof of interest). The helical geometry can be changed by intervening on one or more of the following parameters: number of metallic wires 11, 11a, 11b, diameter of the metallic wires 11, 11a, 11b, diameter (or linear density) of the textile yarn 20 (i.e. number of filaments and/or ends of the textile yarn 20), twisting pitch P, number of textile yarns 20, degree of preforming in the twisting device 60 or in the rubberizing machine.

[0226] Depending on the predetermined helical geometry the metallic reinforcing cord 10 will have different mechanical behavior that translates, in a load-elongation graph, into a different curve. It is thus possible to manufacture metallic reinforcing cords 10 having different rigidities, breaking loads, elongations at break, penetrations and part load elongations.

[0227] FIG. 6 shows a comparative qualitative example of the mechanical behavior of conventional reinforcing cords and of metallic reinforcing cords 10 made in accordance with the present invention.

[0228] On the right the load-elongation curves of various metallic reinforcing cords 10 having different helical geometry are shown.

[0229] On the left, on the other hand, the load-elongation curves of four conventional reinforcing cords are shown: the curve indicated with 1 is of a HE metallic reinforcing cord comprising three strands of metallic wires twisted together, each strand comprising three wires made of steel having a diameter equal to 0.20 mm (such a curve thus has a construction which can be identified as 3×3×0.20 HE), the curve indicated with 2 is of a HE metallic reinforcing cord comprising three strands of metallic wires twisted together, each strand comprising four steel wires having a diameter equal to 0.20 mm (such a curve thus has a construction which can be identified as 3×4×0.20 HE), the curve indicated with 3 is of a HE metallic reinforcing cord comprising three strands of metallic wires twisted together, each strand comprising seven steel wires having a diameter equal to 0.20 mm (such a curve thus has a construction which can be identified as 3×7×0.20 HE), the curve indicated with 4 is of a hybrid reinforcing cord comprising a textile yarn made of polyester (PES) twisted together with three strands of metallic wires, each strand comprising two steel wires having a diameter equal to 0.15 mm (such a curve thus has a construction which can be identified as PES+3×2×0.15).

[0230] FIG. 6 shows that, depending on the predetermined helical geometry (i.e. the construction), the metallic reinforcing cord 10 has a different mechanical behavior, thus being able to achieve rigidities and breaking loads comparable to those of conventional HE metallic reinforcing cords, with part load elongations and/or at break even much greater than those of conventional HE metallic reinforcing cords and of conventional hybrid or mixed textile reinforcing cords.

[0231] FIG. 7 shows, as an example, the load-elongation curves of five metallic reinforcing cords 10 made in accordance with the present invention and having different helical geometry: [0232] the reinforcing cord of the curve indicated with a has a construction (32)+2×0.30 HT; [0233] the reinforcing cord of the curve indicated with b has a construction (32)+4×0.30 HT; [0234] the reinforcing cord of the curve indicated with c has a construction (16)+6×0.14 HT; [0235] the reinforcing cord of the curve indicated with d has a construction (32)+4×0.14 HT; [0236] the reinforcing cord of the curve indicated with e has a construction (32)+6×0.14 HT.

[0237] In the aforementioned constructions the number in brackets indicates the number of ends twisted together to obtain the textile yarn 20 that will then be removed (such a number is thus indicative of the diameter of the textile yarn 20), the number after + indicates the number of metallic wires 11 twisted together with the textile yarn 20, the number after x indicates the diameter of the metallic wires 11 (in mm) and HT indicates the type of steel used.

[0238] FIG. 7 shows that it is possible to manufacture metallic reinforcing cords 10 having part load elongations even equal to 12% and elongations at break even equal to 15%. These values are much greater than those obtainable with conventional metallic reinforcing cords; the latter, indeed, typically have values of part load elongation not greater than 3% and values of elongation at break not greater than 5%, in the case of HE metallic reinforcing cords. It should also be noted that, for example, by increasing the number of ends in the textile yarn 20 (and therefore the diameter of the textile yarn 20) while keeping the other parameters unchanged, the part load elongation and the elongation at break increase, thus keeping the rigidity and the breaking load unchanged (comparison between curves c and e), whereas by decreasing the diameter of the metallic wires 11 while keeping the other parameters unchanged, the part load elongation and the elongation at break increase, thus reducing the rigidity and the breaking load (comparison between curves b and d).

[0239] FIG. 8 shows, as an example, the load-elongation curves of a conventional metallic reinforcing cord (curve A) and of two metallic reinforcing cords 10 having different helical geometries (curves B and C). The reinforcing cord of the curve indicated with A has a construction 3×4×0.175 HE and a twisting pitch equal to 6.3 mm (it is thus a HE metallic reinforcing cord made by twisting together three strands of metallic wires with a twisting pitch equal to 6.3, each strand comprising four steel wires having a diameter equal to 0.175 mm). The reinforcing cord of the curve indicated with B has a construction (36)+3×4×0.175 HE and a twisting pitch equal to 6.3 mm (it is thus a HE metallic reinforcing cord made by twisting together a cord as described above and a textile yarn having 36 ends twisted together). The reinforcing cord of the curve indicated with C has the same identical construction as the reinforcing cord of the curve indicated with B, except for having a greater twisting pitch (equal to 12.5 mm).

[0240] FIG. 8 shows that, while keeping unchanged the twisting pitch, the number of metallic wires, the diameter of the metallic wires and the metallic material, the metallic reinforcing cord 10 made in accordance with the present invention has a part load elongations and an elongation at break much greater than those of a conventional HE metallic reinforcing cord, with no substantial reduction of the rigidity and of the breaking load (comparison between curves A and B). It should also be noted that a change in the helical geometry of the metallic reinforcing cord 10 obtained only by increasing the twisting pitch P results in a reduction of the part load elongations and elongation at break, also in this case with no substantial reduction of the rigidity and of the breaking load with respect to those of a conventional HE metallic reinforcing cord (comparison between curves B and C).

[0241] FIG. 9 shows, as an example, the load-elongation curves of further three metallic reinforcing cords 10 having different helical geometries (curves A, B and C). The reinforcing cord of the curve indicated with A is a HE metallic reinforcing cord made by twisting together three metallic steel wires having a diameter equal to 0.35 mm and a textile yarn having 36 ends twisted together and subjected to conventional preforming systems, in particular of the permanent wave type. Such a cord thus has a construction (36)+3×0.35 HE. The reinforcing cord of the curve indicated with B is a HE metallic reinforcing cord having a construction (36)+4×0.35 HE; it differs from the one discussed above only in that it comprises four metallic wires. The reinforcing cord of the curve indicated with C is a HE metallic reinforcing cord having a construction (36)+5×0.35 HE; it differs from those discussed above only in that it comprises five metallic wires.

[0242] It should be noted that the elongation at break of these reinforcing cords is greater than 6% with a part load elongation varying between 0.2% and 0.7%, whereas the elongation at break of the conventional HE metallic reinforcing cords with identical number and diameter of wires, identical material and identical degree of preforming does not exceed 5%. It should also be noted that when the number of wires increases the breaking load increases as well and, in a less accentuated manner, also the elongation at break increases.

[0243] FIG. 10 shows, as an example, the load-elongation curves of a conventional HE metallic reinforcing cord of the 3×7×0.20 HE type (curve A) and those of four metallic reinforcing cords 10 having different helical geometries (curves B, C, D, E).

[0244] The reinforcing cord of the curve indicated with A is a HE metallic reinforcing cord comprising three strands of metallic wires, each comprising seven metallic wires having a diameter equal to 0.20 mm and a part load elongation increased through preforming. The three strands are twisted together with a twisting pitch equal to 3.15 mm, whereas the seven metallic wires of each strand are twisted together with a twisting pitch equal to 6.3 mm. It thus has a 3×7×0.20 HE construction.

[0245] The reinforcing cord of the curve indicated with B has the same construction above but it is made from an elongated element obtained by winding the aforementioned strands on a textile yarn having 18 ends twisted together. It thus has a (18)+3×7×0.20 HE construction.

[0246] The reinforcing cord of the curve indicated with C has the same construction above but it is made from an elongated element obtained by winding the aforementioned strands on a textile yarn having 36 ends twisted together. It thus has a (36)+3×7×0.20 HE construction.

[0247] The reinforcing cord of the curve indicated with D has the same construction above but it is made from an elongated element obtained by winding the aforementioned strands on a textile yarn having 54 ends twisted together. It thus has a (54)+3×7×0.20 HE construction.

[0248] The reinforcing cord of the curve indicated with E has the same construction above but it is made from an elongated element obtained by winding the aforementioned strands on a textile yarn having 72 ends twisted together. It thus has a (72)+3×7×0.20 HE construction.

[0249] FIG. 10 shows that, while keeping unchanged the twisting pitch, the number of strands and metallic wires in each strand, the diameter of the metallic wires, the metallic material and the degree of preforming, the metallic reinforcing cords 10 made in accordance with the present invention all have part load elongations and elongations at break greater than those of the conventional HE metallic reinforcing cord, with no reduction of rigidity and breaking load. It should also be noted that the part load elongations and elongations at break increase as the number of ends (and therefore the diameter) of the textile yarn used increases.

[0250] The graphs discussed above therefore confirm what has already been stated earlier, i.e. that by changing one or more among number of metallic wires 11, diameter of the metallic wires 11, diameter (or linear density) of the textile yarn 20 (i.e. number of filaments or ends of the textile yarn 20), twisting pitch P, number of textile yarns 20, degree of preforming in the twisting device 60 or in the rubberizing machine, it is possible to manufacture metallic reinforcing cords 10 having different helical geometries (or constructions), thus being able each time to manufacture a metallic reinforcing cord 10 having the mechanical behavior deemed most suitable for the tyre of interest or for the structural component of interest.

[0251] FIGS. 11-20 show, as examples, various metallic reinforcing cords 10 made in accordance with the present invention and respective conventional metallic reinforcing cords, indicated with STD. All of the illustrated reinforcing cords have a helical geometry, but such helical geometry is different depending on the specific construction of each of the illustrated reinforcing cords.

[0252] To the left of each of the illustrated reinforcing cords various cross sections of the reinforcing cord are shown and, to the left of such cross sections the specific construction of the metallic reinforcing cord is given. The twisting pitch in mm is indicated with P and the number of ends of the textile yarn 20 used to manufacture the illustrated metallic reinforcing cords 10 is in brackets.

[0253] The reinforcing cords shown in FIG. 11 are HE metallic reinforcing cords each comprising three metallic strands, each comprising four HT steel wires having a diameter equal to 0.175 mm, twisted together with a twisting pitch equal to 6.3 mm.

[0254] It should be noted that as the construction changes, the helical geometry of the metallic reinforcing cord 10 and the distribution of the metallic wires in a predetermined piece of elastomeric material change. In particular, unlike the conventional HE metallic reinforcing cord in which the metallic wires (in this case grouped in strands) are collected together and concentrated substantially at the center of the aforementioned piece, in the metallic reinforcing cords 10 made in accordance with the present invention the metallic wires (also grouped in strands) are distributed over a wider area of the aforementioned piece as the diameter of the textile yarn and of the twisting pitch increase.

[0255] The reinforcing cords shown in FIG. 12, on the other hand, comprise four HT steel wires having a diameter of 0.30 mm. All of these reinforcing cords have a geometry such that in some or all of their cross sections at least some of the steel wires are in a condition of substantial mutual contact (by this expression meaning both a condition of actual contact of two adjacent steel wires and a condition in which the distance between two adjacent steel wires is much lower than the diameter of the steel wires, in particular equal to or lower than half the diameter of the steel wires, even more in particular lower than one third of the diameter of the steel wires). The two metallic reinforcing cords 10 have a space, defined between the various steel wires and originally occupied by the textile yarn used to manufacture them, which is much greater than that of the conventional metallic reinforcing cord. Such a space increases, while keeping the other parameters unchanged, as the diameter of the textile yarn used increases (and thus as the number of filaments and/or ends of the textile yarn increase). Moving from top to bottom in FIG. 12 the penetration, the elongation at break and the part load elongation increase.

[0256] In accordance with the present invention, it is possible to manufacture metallic reinforcing cords 10 having helical geometries such that in all of their cross sections the metallic wires 11 are in a condition of substantial mutual contact, or metallic reinforcing cords 10 having helical geometries such that in first cross sections of the metallic reinforcing cord 10 some or all of the metallic wires 11 are in a condition of substantial mutual contact and in second cross sections of the metallic reinforcing cord 10 some or all of the metallic wires 11 are spaced apart from one another.

[0257] The present invention also makes it possible to manufacture metallic reinforcing cords 10 having helical geometries such that in all of the cross sections of the metallic reinforcing cord 10 all of the metallic wires 11 are spaced apart from one another.

[0258] The spacing of the metallic wires 11 can be obtained by suitably deforming (or preforming) the metallic reinforcing cords 10 while they are pulled with a predetermined traction force, which can be constant or variable over time. Such a deformation (or preforming) can be obtained by passing the metallic reinforcing cord 10 over a plurality of cylinders having a reduced diameter (for example comprised between 1 and 5 mm) with a predetermined pull. Such deformation is minimum when cylinders of greater diameter are used and maximum when cylinders of smaller diameter are used.

[0259] FIG. 13 shows a conventional metallic reinforcing cord (indicated with STD) and five metallic reinforcing cords 10 made in accordance with the present invention and subjected to suitable deformation so as to space all of the metallic wires from one another. The marking “pref.” indicates the degree of deformation (minimum or maximum) to which the metallic reinforcing cord 10 has been subjected to have all of the metallic wires spaced apart from each other.

[0260] All of the reinforcing cords shown in FIG. 13 comprise five UT steel wires having a diameter equal to 0.22 mm.

[0261] It should be noted that, while keeping the other parameters unchanged, as the twisting pitch P increases the helical geometry of the metallic reinforcing cord 10 and the distribution of the metallic wires in a predetermined piece of elastomeric material change. In particular, unlike the conventional metallic reinforcing cord in which the metallic wires are collected together and concentrated substantially at the center of the aforementioned piece, in the metallic reinforcing cords 10 the metallic wires are distributed over the entire volume of the aforementioned piece.

[0262] It should also be noted that, while keeping the other parameters unchanged, the greater the deformation, the greater the distribution of the metallic wires over the entire volume of the piece of elastomeric material (comparison between the last two reinforcing cords at the bottom of FIG. 11). The degree of deformation imparted on the metallic reinforcing cord 10 can thus also be considered as a useful parameter on which to intervene to provide the metallic reinforcing cord 10 with the helical geometry (and therefore the mechanical behavior) deemed ideal for the particular application required.

[0263] The distribution of the metallic wires inside the aforementioned structural component can be changed by changing, over time, the amount of the traction force with which the metallic reinforcing cord 10 is pulled during the aforementioned deformation or during the process of incorporation of the metallic reinforcing cord 10 in the piece of elastomeric material to make the structural component of interest of the tyre.

[0264] In accordance with the present invention, since it is possible to have very large twisting pitches (for example equal to 35 mm) with no risk of unravelling, it is possible to manufacture very flat metallic reinforcing cords 10. This makes it possible to double, or more generally multiply, the number of metallic reinforcing cords provided in a specific portion of piece of structural component with respect to the case where conventional metallic reinforcing cords are used.

[0265] FIG. 14 shows the HE metallic reinforcing cords discussed with reference to FIG. 10.

[0266] FIG. 15 shows four metallic reinforcing cords 10 made in accordance with the present invention. In order to manufacture each of such metallic reinforcing cords 10 two textile yarns were used, each comprising 16 ends twisted together (first and third cord in FIG. 15 moving from top to bottom) or 36 ends twisted together (second and fourth cord in FIG. 15 moving from top to bottom). The two textile yarns were twisted together with four UT steel wires having a diameter equal to 0.30 mm. It should be noted that as the number of ends of the textile yarn and the twisting pitch increase the metallic wires tend to be arranged almost parallel. In this case, the part load elongation is low but the machine output increases.

[0267] Similar considerations on the correlation between twisting pitch and machine output and/or between number of ends of the textile yarn and machine output can be made with reference to the metallic reinforcing cords 10 shown in FIGS. 16-20. The first reinforcing cord shown in each of the aforementioned figures is a conventional metallic reinforcing cord, indicated with STD. The construction of each of the reinforcing cords shown in FIGS. 16-20 is clear in light of the indications given in the aforementioned figures alongside the aforementioned reinforcing cords and of the examples discussed above.

[0268] The Applicant has made further examples of metallic reinforcing cords 10 and has compared the mechanical behavior of these reinforcing cords with that of hybrid and conventional metallic reinforcing cords. The result of the comparison is indicated in table 1 below.

TABLE-US-00001 TABLE 1 Breaking Elongation at Part Load load break Elongation (N) (%) (%) (36 + 36) + 4 × 0.30 UT 979 4.8 2.68 (16 + 16) + 4 × 0.30 UT 981 3.69 1.51 (16) + 6 × 0.30 HT 1062 5.48 1.40 (32) + 6 × 0.30 HT 1113 9.85 2.37 PES + 5 × 0.28 907 3.62 0.54 PES + 5 × 0.25 729 3.99 0.74

[0269] In table 1, the first four cords are metallic reinforcing cords 10 in accordance with the present invention whereas the last two cords are conventional reinforcing cords. These last two conventional reinforcing cords are hybrid reinforcing cords comprising a textile yarn made of polyester (PES) twisted together with five metallic wires having a diameter equal to 0.28 mm (the penultimate cord in table 1) and 0.25 mm (the last cord in table 1).

[0270] In the first two metallic reinforcing cords 10 of table 1 the Applicant has used two textile yarns, each respectively comprising 36 ends (in the first reinforcing cord) and 16 ends (in the second reinforcing cord). Such textile yarns were twisted together with four UT steel wires having a diameter equal to 0.30 mm. In the third and fourth metallic reinforcing cord 10 of table 1 the Applicant has used a single textile yarn comprising 16 ends (in the third reinforcing cord) and 32 ends (in the fourth reinforcing cord). Such a textile yarn was twisted together with six UT steel wires having a diameter equal to 0.30 mm.

[0271] It should be noted that some of the metallic reinforcing cords 10 of table 1 have a (and even much greater) part load elongation and elongation at break greater than those of conventional hybrid or metallic reinforcing cords, with substantially identical rigidity and breaking load.

[0272] The Applicant made further examples of metallic reinforcing cords 10 and has compared the mechanical behavior of these reinforcing cords with those of a conventional HE metallic reinforcing cord of analogous construction. All of these metallic reinforcing cords comprise three strands twisted together, each strand comprising seven metallic wires having a diameter equal to 0.20 mm (such metallic reinforcing cord thus have a 3×7×0.20 HE construction). The strands are twisted together with a first twisting pitch, whereas the metallic wires in each strand are twisted together with a second twisting pitch. The result of the comparison is indicated in table 2 below.

TABLE-US-00002 TABLE 2 Breaking Elongation at Part Load load break Elongation (N) (%) (%) 3 × 7 × 0.20 HE 1833 4.19 1.87 1 + 1 × (36) + 3 × 7 × 0.20 HE 1617 14.58 4.16 3 × (36) + 3 × 7 × 0.20 HE 1827 5.04 2.40 1 + 2 × (36) + 3 × 7 × 0.20 HE 1817 12.40 6.78 1 + 3 × (36) + 3 × 7 × 0.20 HE 1844 12.97 6.89

[0273] In table 2, the first cord is a conventional metallic reinforcing cord, whereas the other four cords are metallic reinforcing cords 10 in accordance with the present invention: they differ from each other by the type of textile yarn used to manufacture them.

[0274] In the conventional metallic reinforcing cord, the first twisting pitch is equal to 3.8 mm, whereas the second twisting pitch is equal to 6.3 mm.

[0275] In the metallic reinforcing cord 10 having the construction 1+1×(36)+3×7×0.20 HE a central textile yarn comprising 36 ends and a crown textile yarn comprising 36 ends are used. These two textile yarns are twisted together with the aforementioned strands of metallic wires. The first twisting pitch is equal to 3.15 mm, whereas the second twisting pitch is equal to 6.3 mm.

[0276] In the metallic reinforcing cord 10 having the construction 3×(36)+3×7×0.20 HE three textile yarns are used, each comprising 36 ends. Such textile yarns are twisted together with the aforementioned strands of metallic wires. The first twisting pitch is equal to 4.2 mm, whereas the second twisting pitch is equal to 12.5 mm.

[0277] In the metallic reinforcing cord 10 having the construction 1+2×(36)+3×7×0.20 HE a central textile yarn comprising 36 ends and two crown textile yarns each comprising 36 ends are used. These three textile yarns are twisted together with the aforementioned strands of metallic wires. The first twisting pitch is equal to 4.2 mm, whereas the second twisting pitch is equal to 12.5 mm.

[0278] In the metallic reinforcing cord 10 having the construction 1+3×(36)+3×7×0.20 HE a central textile yarn comprising 36 ends and three crown textile yarns each comprising 36 ends are used. These four textile yarns are twisted together with the aforementioned strands of metallic wires. The first twisting pitch is equal to 4.2 mm, whereas the second twisting pitch is equal to 12.5 mm.

[0279] It should be noted that some of the metallic reinforcing cords 10 have an elongation at break greater (and even much greater, see the values 12.4% and 14.58%) than that of the conventional metallic reinforcing cord, with a substantially identical rigidity and breaking load.

[0280] The Applicant has made further examples of metallic reinforcing cords 10 deemed suitable for being used in the carcass and has evaluated their breaking load and the respective elongation at break. Such reinforcing cords and the result of the aforementioned evaluation is indicated in table 3 below.

[0281] Each of the two cords indicated in table 3 comprises twelve metallic wires made of UT steel having a diameter equal to 0.22 mm and twisted together with a predetermined twisting pitch. These cords are obtained by twisting together the aforementioned metallic wires and a textile yarn (which is then removed) comprising 16 ends twisted together, with a twisting pitch equal to 12.5 mm. The two cords differ from each other only in that in the second the metallic wires have been subjected to a preforming before being twisted together with the textile yarn.

TABLE-US-00003 TABLE 3 Breaking Elongation at Part Load load break Elongation (N) (%) (%) (16) + 12 × 0.22 UT 1611 3.57 1.06 (16) + 12 × 0.22 UT 1604 4.64 1.76

[0282] The Applicant has observed that typically the metallic reinforcing cords used in the carcass structure of the tyres do not allow a suitable penetration of the surrounding elastomeric material due to their particularly closed geometry. In such reinforcing cords typically the metallic wires would be in mutual contact and thus subject to the undesired phenomenon of fretting, at the expense of the structural integrity of the tyre.

[0283] The metallic reinforcing cords 10 made in accordance with the present invention (like for example the two cords indicated in table 3) on the other hand, thanks to the free space obtained through the removal of the textile yarn and to the possibility of spacing apart the various metallic wires, allow adequate penetration of the elastomeric material inside the cord and prevent the mutual contact of the various metallic wires, at the same time reaching values of breaking load, elongation at break and part load elongations which are more than acceptable for the specific application. It is thus possible to achieve the desired structural integrity of the tyre with a smaller number of metallic wires in the carcass structure or, the number of metallic wires being equal, with metallic wires having a smaller diameter, with consequent advantages in terms of weight and cost of the tyre.

[0284] All of the example discussed above and shown in the attached figures demonstrate just how large is the possibility of manufacturing, through the process and/or the apparatus of the present invention, metallic reinforcing cords 10 having different mechanical behaviors, making it possible to identify each time the ideal one for the specific application. In particular, the reinforcing cords 10 can be used in the crossed belt structure and/or in the chafer and/or in the flipper and/or in the zero degrees belt layer of tyres for automobiles, in the zero degrees belt layer and/or in the chafer and/or in the flipper of tyres for motorcycles and in the carcass structure and/or in the crossed belt structure and/or in the chafer and/or in the flipper and/or in the zero degrees belt layers and/or in the stoneguard layer of tyres for heavy and/or light load vehicles.

[0285] Among the particularly advantageous aspects thereof, the present invention makes it possible, in preferred embodiments thereof, to manufacture metallic reinforcing cords 10 for tyres for automobiles, motorcycles and heavy and/or light load vehicles that comprise at least one metallic wire 11 that extends along a helical path, preferably at least two metallic wires 11 twisted together with a predetermined twisting pitch, and have a part load elongation preferably greater than 1%, more preferably greater than 2%, more preferably greater than 3%, even more preferably greater than 3.5%, even more preferably greater than 4%, and/or an elongation at break preferably greater than 5%, more preferably lower than 20%, even more preferably up to 15%, and/or wherein said at least one metallic wire 11 has a winding pitch (or, in the case of a plurality of metallic wires, they are twisted together with a twisting pitch) that is preferably greater than 2 mm, more preferably greater than 3 mm, even more preferably greater than 4 mm, even more preferably greater than 5 mm, allowing values of part load elongation and of elongation at break to be reached such as to be able to use such reinforcing cords also in types of tyres and/or in structural components of tyres in which it has not been possible to use conventional metallic reinforcing cords yet.

[0286] This is what also emerged from a series of comparative laboratory tests carried out by the Applicant. Such tests demonstrated that the elongation at break and the part load elongation of metallic reinforcing cords 10 made in accordance with the present invention can reach values even much greater than those of the corresponding conventional metallic reinforcing cords.

[0287] Hereinafter, all of the ranges of values are obtained considering all of the following combinations of diameter of the metallic wires 11 and number of metallic wires 11: minimum diameter and minimum number of metallic wires 11, maximum diameter and minimum number of metallic wires 11, minimum diameter and maximum number of metallic wires 11, maximum diameter and maximum number of metallic wires 11.

[0288] The Applicant simulated the mechanical behavior of metallic reinforcing cords 10 having a n×D construction, comprising a plurality of metallic wires 11 twisted together, preferably with a single twisting pitch, where n is the number of such metallic wires 11, preferably comprised between 2 and 6, for example equal to 2 or 3 or 4, and D is the diameter of the metallic wires 11, selected among any of the diameter values cited above and preferably equal for all of the metallic wires 11 of the metallic reinforcing cord 10. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.5%-2.0% and values of part load elongation comprised in the range 0.2%-0.8%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.5%-15% and those of part load elongation were comprised in the range 0.2%-10%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layer of tyres for automobiles, in the zero degrees belt layer and/or in the chafer and/or flipper of tyres for motorcycles, in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layers and/or in the stoneguard layer of tyres for heavy and/or light load vehicles and, with a number of metallic wires 11 greater than 6, preferably greater than or equal to 9, also in the carcass structure of tyres for heavy and/or light load vehicles.

[0289] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having a n+1×D or 1+n×D construction, comprising a strand of metallic wires 11 twisted together with a first twisting pitch, the strand being twisted together with a single metallic wire 11 with a second twisting pitch that can be equal to or different from the first twisting pitch, preferably equal, where n is the number of metallic wires 11 of the strand, which preferably is comprised between 1 and 6, for example equal to 1 or 2, and D is the diameter of the metallic wires 11, selected among any of the diameter values cited above, preferably equal for all of the metallic wires 11 of the strand and not necessarily equal to that of the single metallic wire 11. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.3%-1.8% and values of part load elongation comprised in the range 0.2%-0.7%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.3%-10% and the values of part load elongation were comprised in the range 0.2%-8.0%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layer of tyres for automobiles, in the zero degrees belt layer and/or in the chafer and/or flipper of tyres for motorcycles, in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layers and/or in the stoneguard layer of tyres for heavy and/or light load vehicles and, with a number of metallic wires 11 greater than 6, preferably greater than or equal to 9, also in the carcass structure of tyres for heavy and/or light load vehicles.

[0290] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having a m+n×D construction, comprising a strand of metallic wires 11 twisted together with a first twisting pitch, the strand being twisted together with a plurality of other metallic wires 11 with a second twisting pitch that can be equal to or different from the first twisting pitch (preferably equal), where m is the number of metallic wires 11 of the strand, which preferably is comprised between 1 and 6, for example equal to 2 or 3 or 4, and n is the number of the other metallic wires 11, which preferably is comprised between 1 and 6, for example equal to 2 or 3, and where D is the diameter of the metallic wires 11, selected among any of the diameter values cited above, preferably equal for all of the metallic wires 11 of the strand and not necessarily equal to that of the other metallic wires 11. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.5%-2.0% and values of part load elongation comprised in the range 0.2%-0.8%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.5%-15% and those of part load elongation were comprised in the range 0.2%-10%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layer of tyres for automobiles, in the zero degrees belt layer and/or in the chafer and/or flipper of tyres for motorcycles, in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layer and/or in the stoneguard layer of tyres for heavy and/or light load vehicles and, with a number of metallic wires 11 greater than 6, preferably greater than or equal to 9, also in the carcass structure of tyres for heavy and/or light load vehicles.

[0291] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10, preferably of the HE type, having a m×n×D construction, comprising a plurality of strands of metallic wires 11 twisted together with a first twisting pitch, each strand comprising a plurality of metallic wires twisted together with a second twisting pitch that can be equal to or different from the first twisting pitch (preferably equal), where m is the number of strands, which preferably is comprised between 2 and 5, for example equal to 2 or 3 or 5, and n is the number of metallic wires 11 of each strand, which preferably is comprised between 2 and 7 and may or may not be equal to m, for example equal to 2 or 3 or 6 or 7, where D is the diameter of the metallic wires 11 preferably equal for all of the metallic wires 11 of all of the strands. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 2.0%-4.5% and values of part load elongation comprised in the range 1.0%-2.5%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 2.0%-15% and those of part load elongation were comprised in the range 1.0%-7.0%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layer of tyres for automobiles, in the zero degrees belt layer and/or in the chafer and/or flipper of tyres for motorcycles, in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layers and/or in the stoneguard layer of tyres for heavy and/or light load vehicles and, with a number of metallic wires 11 greater than 6, preferably greater than or equal to 9, also in the carcass structure of tyres for heavy and/or light load vehicles.

[0292] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10, preferably of the HE type or preformed, having a n×D construction, comprising a plurality of metallic wires 11 twisted together, preferably with a single twisting pitch, where n is the number of such metallic wires 11, preferably comprised between 2 and 6, for example equal to 3, 4 o 5, and D is the diameter of the metallic wires 11, selected among any of the diameter values cited above and preferably equal for all of the metallic wires 11 of the metallic reinforcing cord 10. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction. Depending on the diameter of the metallic wires selected each time, the Applicant measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 3.0%-6.0% and values of part load elongation comprised in the range 0.2%-0.5%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 3.0%-8.0% and those of part load elongation were comprised in the range 0.2%-1.0%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the zero degrees belt layer and/or in the chafer and/or flipper of tyres for motorcycles and/or in the crossed belt structure and/or in the zero degrees belt layers and/or in the stoneguard layer and/or in the chafer and/or flipper of tyres for heavy and/or light load vehicles and, with a number of metallic wires 11 greater than 6, preferably greater than or equal to 9, also in the carcass structure of tyres for heavy and/or light load vehicles.

[0293] With particular reference to the applications in tyres for heavy and/or light load vehicles, the Applicant also carried out the following comparative laboratory tests.

[0294] The Applicant simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the 1+n×D type similar to the 1+n×D constructions cited above, where n is lower than or equal to 6. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 3.0%-6.0% and values of part load elongation comprised in the range 0.2%-0.5%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 3.0%-8.0% and the values of part load elongation were comprised in the range 0.2%-1.0%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the stoneguard layer and/or in the zero degrees belt layers and/or in the chafer and/or flipper of tyres for heavy and/or light load vehicles.

[0295] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the 1+n×D type similar to the constructions 1+n×D cited above, but where n is greater than 6, preferably greater than or equal to 9, for example equal to 18. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.0%-2.0% and values of part load elongation comprised in the range 0%-0.1%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.0%-2.5% and the values of part load elongation were comprised in the range 0%-0.5%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction can have a preferred application also in the carcass structure of tyres for heavy and/or light load vehicles.

[0296] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the m+n×D type similar to the m+n×D constructions cited above, where m is equal to 1 or 2 and the twisting pitch of the metallic wires 11 of the strand is different from that of the other metallic wires 11. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 3.0%-6.0% and values of part load elongation comprised in the range 0.2%-0.5%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 3.0%-8.0% and the values of part load elongation were comprised in the range 0.2%-1.0%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the chafer and/or flipper and/or in the zero degrees belt layers and/or in the stoneguard layer of tyres for heavy and/or light load vehicles and, in the case in which m, n or m+n is greater than 6, preferably greater than or equal to 9, also in the carcass structure of such tyres.

[0297] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the m+n×D type similar to the m+n×D constructions cited above, but where m is equal to 3 and n is lower than 6. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.5%-2.5% and values of part load elongation comprised in the range 0.1%-0.2%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.5%-4.0% and the values of part load elongation were comprised in the range 0.1%-0.8%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the crossed belt structure and/or in the chafer and/or flipper and/or in the stoneguard layer and/or in the zero degrees belt layers of tyres for heavy and/or light load vehicles.

[0298] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the m+n×D type similar to the m+n×D constructions cited above, but where m is equal to 3 and n is greater than 6, for example equal to 8 or 9. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.5%-2.5% and values of part load elongation comprised in the range 0.1%-0.2%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.5%-4.0% and the values of part load elongation were comprised in the range 0.1%-0.8%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the carcass structure, in the crossed belt structure and/or in the chafer and/or flipper and/or in the stoneguard layer and/or in the zero degrees belt layers of tyres for heavy and/or light load vehicles.

[0299] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the n×D type similar to the n×D constructions cited above, but where n is greater than 6, for example equal to 11 or 12. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.5%-2.5% and values of part load elongation comprised in the range 0.1%-0.2%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.5%-4.0% and the values of part load elongation were comprised in the range 0.1%-0.8%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the carcass structure and/or in the crossed belt structure and/or in the chafer and/or flipper and/or in the stoneguard layer and/or in the zero degrees belt layers of tyres for heavy and/or light load vehicles.

[0300] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the 1+m+n×D or 2+m+n×D type, comprising one metallic wire 11, or two metallic wires 11, or three metallic wires 11 twisted together with a first twisting pitch, such metallic wire(s) 11 being twisted together with a first strand of metallic wires 11 with a first twisting pitch of the strand that can be equal to or different from said first twisting pitch and with a second strand of metallic wires 11 with a second predetermined twisting pitch of the strand that can be equal to or different from the first twisting pitch and that is preferably different from the first twisting pitch of the strand, where m is the number of metallic wires 11 of the first strand and n is the number of metallic wires of the second strand, and D is the diameter of the metallic wires 11, selected among any of the diameter values cited above, preferably equal for all of the metallic wires 11 of the metallic reinforcing cord 10. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.0%-2.0% and values of part load elongation comprised in the range 0%-0.1%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.0%-2.5% and the values of part load elongation were comprised in the range 0%-0.5%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the carcass structure and/or in the crossed belt structure and/or in the chafer and/or flipper and/or in the stoneguard layer and/or in the zero degrees belt layers of tyres for heavy and/or light load vehicles.

[0301] The Applicant also simulated the mechanical behavior of metallic reinforcing cords 10 having constructions of the n×D type similar to the n×D constructions cited above, but where n is greater than 18, for example equal to 27. The Applicant compared the mechanical behavior of such metallic reinforcing cords 10 with that of corresponding conventional metallic reinforcing cords having the same construction and measured, for the conventional metallic reinforcing cords, values of elongation at break comprised in the range 1.0%-2.0% and values of part load elongation comprised in the range 0%-0.1%, whereas for the metallic reinforcing cords 10 made in accordance with the present invention the values of elongation at break were comprised in the range 1.0%-2.5% and the values of part load elongation were comprised in the range 0%-0.5%. According to the Applicant, metallic reinforcing cords 10 having the aforementioned construction have a particularly preferred application in the carcass structure of tyres for heavy and/or light load vehicles.

[0302] The Applicant believes that in tyres for automobiles it is particularly preferred to use metallic reinforcing cords 10 having a n×D or m×n×D construction. The main advantages offered by the use of such reinforcing cords are the high capability of penetration of the elastomeric material between the various metallic wires 11, the high elongation at break, with consequent high rigidity, and the high part load elongation. Such advantages produce benefits in terms of performance, also at high speeds. For applications in the zero degrees belt layers it is also deemed particularly preferred to use metallic reinforcing cords 10 having a m×n×D construction.

[0303] In the previous paragraph and in the subsequent ones, the terms “high” should not necessarily be interpreted in absolute terms but rather also in relative terms with respect to the corresponding features of the conventional metallic reinforcing cords having the same construction. Therefore, with reference for example to the part load elongations, it is considered high simply when it is higher than that of the corresponding conventional metallic reinforcing cords.

[0304] The Applicant also believes that in tyres for motorcycles it is particularly preferred to use metallic reinforcing cords 10 having a n×D or m×n construction. In this case, the main advantages offered by the use of such reinforcing cords are the high capability of penetration of the elastomeric material between the various metallic wires 11 and the high part load elongation, with consequent high rigidity. Such advantages produce benefits in terms of weight and performance. A further advantage offered by such reinforcing cords, the elongation at break being equal to that of the conventional HE or preformed metallic reinforcing cords, is the increase of the machine output, with consequent economic and production benefits.

[0305] The Applicant also believes that in the carcass structure of tyres for heavy and/or light load vehicles it is particularly preferred to use metallic reinforcing cords 10 having a 1+n×D or m+n+p (i.e. wherein a strand of m metallic wires is twisted together with n metallic wires with a first twisting pitch to form an assembly that is then twisted together with p metallic wires with a second twisting pitch different from the first twisting pitch) or n×D construction. In this case, the main advantage offered by the use of such reinforcing cords is the high capability of penetration of the elastomeric material between the various metallic wires 11, with consequent benefits in terms of fatigue resistance and integrity of the tyre, and thus of mileage.

[0306] As to the tyres for heavy and/or light load vehicles, the Applicant believes that it is particularly preferred to use, in their crossed belt structures, metallic reinforcing cords 10 having a 1+n×D or 2+n×D or 3+n×D construction. Also in this case, the main advantage offered by the use of such reinforcing cords is the high capability of penetration of the elastomeric material between the various metallic wires 11, with consequent benefits in terms of resistance to detachment phenomena of the elastomeric material from the metallic wires of the crossed belt structure during the reconstruction of the tyre.

[0307] The Applicant believes that it is particularly preferred to use in the zero degrees belt layers of the tyres for heavy and/or light load vehicles, metallic reinforcing cords 10 having a n×D or m×n×D construction (where n can also be equal to m). In this case, the main advantages offered by the use of such reinforcing cords are the high capability of penetration of the elastomeric material between the various metallic wires 11, the high elongation at break, with consequent high rigidity and the high part load elongation. Such advantages product benefits in terms of performance. A further advantage offered by such reinforcing cords, the elongation at break being equal to that of conventional preformed or HE metallic reinforcing cords, is the increase of the machine output, with consequent economic and production benefits.

[0308] The Applicant believes that it is particularly preferred to use in the stoneguard layers of the tyres for heavy and/or light load vehicles, metallic reinforcing cords 10 having a n×D and m×n×D construction (where n can also be equal to m). In this case, the main advantage offered by the use of such reinforcing cords is the high capability of penetration of the elastomeric material between the various metallic wires 11, with consequent benefits in terms of performance, comfort and impact resistance. A further advantage offered by such reinforcing cords, the elongation at break being equal to that of conventional preformed or HE metallic reinforcing cords, is the increase of the machine output, with consequent economic and production benefits.

[0309] The Applicant believes that it is particularly preferred to use in the chafer and/or flipper of the tyres for heavy and/or light load vehicles, metallic reinforcing cords 10 having a m×n×D (where n can also be equal to m) or 1+n×D or 2+n×D or 3+n×D construction. In this case, the main advantage offered by the use of such reinforcing cords is the high part load elongation, with consequent benefits in terms of flexibility of such structures, and therefore of resistance to fatigue stresses, which implies an improvement in performance. A further advantage offered by such reinforcing cords, the elongation at break being equal to that of conventional preformed or HE metallic reinforcing cords, is the increase of the machine output, with consequent economic and production advantages.

[0310] The present invention has been described with reference to some preferred embodiments. Different changes can be made to the embodiments described above, while remaining within the scope of protection of the invention as defined by the following claims.