Simplified manufacturing method for a tire having a single working layer

Abstract

The present invention relates to a method for manufacturing a tire, the tire comprising a carcass ply and a single working ply, wherein the working filamentary reinforcing elements (180) form an angle AT of 27° to 40° with the circumferential direction of the tire. In the method, a carcass assembly is formed by winding a carcass ply, the carcass assembly being intended to form the carcass ply, wherein the filamentary carcass reinforcing elements (340) form an initial angle A3 with an absolute value of 80° to 90° with the circumferential direction (x) of the support member.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a tire and a tire obtained by such a method. Background Art

[0002] From the prior art, and in particular from EP3489035, tires are known that include a crown, two sidewalls, and two beads, with each sidewall connecting each bead to the crown respectively. Each bead includes at least one circumferential reinforcing element, typically in the form of a bead wire.

[0003] The tire further includes a carcass reinforcement that is anchored in each bead and extends in each sidewall and the crown. The carcass reinforcement includes a single carcass ply that wraps around each circumferential reinforcing element.

[0004] The crown includes a tread intended to contact the ground during tire operation and a crown reinforcement radially disposed between the tread and the carcass reinforcement. The crown reinforcement includes a working reinforcement that includes a single working ply. The crown reinforcement further includes a hoop reinforcement radially disposed outside the working reinforcement.

[0005] As described above, a specific feature of the tire described in EP3489035 compared to conventional tires where the working reinforcement includes two working plies is the elimination of one working ply. In EP3489035, the advantage of eliminating one working ply is that it reduces the amount of material used in the tire, thus reducing the mass of the tire, while improving the circumferential stiffness of the tire, which in turn results in a reduction in shear stiffness, but this reduction is acceptable considering the material savings.

[0006] The method for manufacturing a tire in EP3489035 includes the following steps known from the prior art, and in particular from FR2797213 and FR1413102: forming a carcass assembly intended to form the carcass ply by winding a carcass ply around a support. The carcass assembly includes carcass filamentary reinforcing elements that extend along a main direction that forms an initial angle with the circumferential direction of the support, the initial angle depending on the angle intended to be obtained in the tire after the manufacturing method.

[0007] Next, a working assembly intended to form the working ply is formed by radially winding a working ply around the outside of the carcass assembly. The working assembly includes working filamentary reinforcing elements that extend along a main direction that forms an initial angle with the circumferential direction of the support, the initial angle in turn depending on the angle intended to be obtained in the tire after the manufacturing method. Then, the carcass assembly and the working assembly form an assembly having a generally cylindrical shape.

[0008] Next, deform a component having a substantially cylindrical shape so as to obtain a component having a substantially toroidal shape such that:

[0009] - In an axial central portion of the carcass component that extends axially and is radially aligned with the working component, the final angle formed between the main direction of each carcass filamentary reinforcing element and the circumferential direction of the support is equal to 70° for variant form S1 in EP3489035 and equal to 43° for variant form S2, and

[0010] - The final angle formed between the main direction of each working filamentary reinforcing element and the circumferential direction of the support is equal to -40° for variant form S1 in EP3489035 and equal to -24° for variant form S2.

[0011] Next, crosslink a green-form tire obtained from the component having a substantially toroidal shape so as to obtain a tire. In the tire, the main direction of each carcass filamentary reinforcing element forms an angle with the circumferential direction of the tire that is equal to the final angle obtained after the deformation step. The main direction of each working filamentary reinforcing element forms an angle with the circumferential direction of the tire that is equal to the final angle obtained after the deformation step.

[0012] Before the step of forming the carcass component by winding the carcass ply, the carcass ply is produced by arranging carcass filamentary reinforcing elements parallel to each other and embedding them (e.g., by surface coating) in an uncrosslinked composition comprising at least one elastomer, which composition is intended to form an elastomeric matrix after crosslinking. A ply called a straight ply is obtained, in which the carcass filamentary reinforcing elements are parallel to each other and parallel to the main direction of the carcass ply. Next, sections of the carcass ply are cut at a cutting angle, and these sections are butt-jointed to each other to obtain a ply called an angle ply, in which the main direction in which the carcass filamentary reinforcing elements extend parallel to each other forms an angle equal to the cutting angle with the main direction of the carcass ply, which angle is equal to the above-mentioned initial angle. The working layer is manufactured in a similar manner.

[0013] In order to obtain the same final angles in tires of different sizes, it is necessary to use different initial angles to account for the different degrees of shaping between different sizes, which theoretically makes it necessary to manufacture as many carcass plies and working plies as there are tire sizes in existence. However, managing such a large number of plies in a factory is complex and costly. Summary of the Invention

[0014] The object of the present invention is to allow the simplified manufacture of a tire including a single working layer from a limited number of carcass plies and working plies while maintaining the main mechanical properties of the tire, namely its shear stiffness and circumferential stiffness.

[0015] Method according to the present invention

[0016] To this end, the subject of the present invention is a method for manufacturing a tire, the tire comprising a crown, two sidewalls and two beads, each sidewall connecting each bead to the crown respectively, the tire comprising carcass reinforcement anchored in each bead, the carcass reinforcement extending in each sidewall and radially inside the crown, the carcass reinforcement comprising at least one carcass ply, the crown comprising:

[0017] - a tread intended to come into contact with the ground during the operation of the tire,

[0018] - a crown reinforcement radially arranged between the tread and the carcass reinforcement, the crown reinforcement comprising a working reinforcement with a single working ply, the working ply being axially delimited by two axial edges of the working ply and comprising working filamentary reinforcement elements, the working filamentary reinforcement elements extending axially from one axial edge of the working ply to the other axial edge substantially parallel to each other along the main direction of each working filamentary reinforcement element, the main direction of each working filamentary reinforcement element forming an angle AT with the circumferential direction of the tire,

[0019] wherein, in the method:

[0020] - arranging a carcass assembly intended to form at least one carcass ply around a support, the support having a generally cylindrical shape around a main axis, the carcass assembly being axially delimited by two axial edges of the carcass assembly and comprising carcass filamentary reinforcement elements, the carcass filamentary reinforcement elements extending axially from one axial edge of the carcass assembly to the other axial edge substantially parallel to each other, each carcass filamentary reinforcement element extending in the carcass assembly along the main direction of each carcass filamentary reinforcement element, the main direction of each carcass filamentary reinforcement element forming an initial angle A3 with the circumferential direction of the support,

[0021] - arranging a working assembly intended to form the working ply radially outside the carcass assembly, the carcass assembly and the working assembly forming an assembly having a generally cylindrical shape around the main axis of the support,

[0022] - deforming the assembly having a generally cylindrical shape around the main axis of the support so as to obtain an assembly having a generally toroidal shape around the main axis of the support,

[0023] - crosslinking the green tire obtained from the assembly having a generally toroidal shape so as to obtain the tire,

[0024] wherein, in the method, the absolute value of the angle A3 is from 80° to 90°, and the absolute value of the angle AT is from 27° to 40°.

[0025] By using an initial angle A3 with an absolute value of between 80° and 90°, it is sufficient to have one or more carcass plies for arranging the carcass assembly, each ply having a single cutting angle, in this case the cutting angle being between 80° and 90°. Thus, the need to manufacture as many carcass plies as there are tire sizes present can be avoided. The angular range of 80° to 90° makes it possible to take into account the industrial variability of the manufacturing method (especially during the surface coating step), which industrial variability gives rise to such straight plies where the initial angle A3 may oscillate up to 10° around the theoretical value of 90°. Implicitly, the initial angle A3 is constant when moving axially from one axial edge of the carcass assembly to the other axial edge.

[0026] In a tire, the angle of the main direction of each carcass filamentary reinforcing element in the axially central part of the carcass ply thus depends on the shaping degree and the initial angle of the main direction of each working filamentary reinforcing element. Thus, the main mechanical properties of the tire (i.e. its shear stiffness and circumferential stiffness) can be simply obtained by varying the initial angle of the main direction of each working filamentary reinforcing element according to the shaping degree. Thus, the method according to the invention makes it possible to only need to manage the different working plies.

[0027] As shown by the results of the following tests, satisfactory shear stiffness and circumferential stiffness can be obtained in the angular range AT of 27° to 40°. Although a slight decrease in these stiffnesses (especially the circumferential stiffness) was observed, this decrease is largely compensated for by the simplified method and the reduction in the number of carcass plies to be managed.

[0028] According to the invention, the working reinforcement comprises a single working layer. The presence of a single working layer makes it possible in particular to reduce the weight of the tire, thus reducing the energy dissipated by the hysteresis of the crown and thus reducing the rolling resistance of the tire. Thus, apart from the working layer, the working reinforcement does not have any layer reinforced by filamentary reinforcing elements. The filamentary reinforcing elements of such reinforcement layers excluded from the working reinforcement of the tire include metallic filamentary reinforcing elements and fabric filamentary reinforcing elements. Very preferably, the working reinforcement consists of a single working layer.

[0029] The carcass assembly can be intended to form a single carcass ply, or intended to form two carcass plies, for example by winding the carcass assembly two times. Thus, in an embodiment where the tire comprises two carcass plies, a single carcass assembly can be arranged (for example by winding it two times), or a first radially inner carcass assembly can be arranged and then a second radially outer carcass assembly arranged around the first radially inner carcass assembly, the first carcass assembly and the second carcass assembly each being intended to form each carcass ply.

[0030] Within the scope of the present invention, the working assembly is intended to form a single working layer.

[0031] In a preferred embodiment where a relatively simple method can be used, a carcass assembly is formed by winding one or more carcass plies around a support member, and a working assembly is formed by radially winding one or more working plies on the outside of the carcass assembly.

[0032] In a simplified method where only one carcass ply needs to be processed to form each carcass assembly and circumferential joints will be avoided between multiple carcass plies having an axial width smaller than the axial width of each carcass assembly intended to be formed, each carcass assembly is constituted by the carcass ply intended to form each carcass layer. In other words, each carcass ply is axially continuous.

[0033] In the case where each carcass assembly is formed by multiple carcass plies, it is preferred to use multiple carcass plies in which the main directions of the carcass filamentary reinforcing elements are all parallel to each other.

[0034] Similarly, in a simplified method where only one working ply needs to be processed to form the working assembly and circumferential joints will be avoided between multiple working plies having an axial width smaller than the axial width of the working assembly intended to be formed, the working assembly is obtained from the working ply intended to form a single working layer. In other words, the working ply is axially continuous.

[0035] In the case where the working assembly is formed by multiple working plies, it is preferred to use multiple working plies in which the main directions of the working filamentary reinforcing elements are all parallel to each other. Of course, it is conceivable that the main directions of the working filamentary reinforcing elements are not parallel to each other from one working ply to another.

[0036] The tire of the present invention is preferably intended for passenger vehicles as defined according to the European Tyre and Rim Technical Organization or "ETRTO" standard of 2019. The cross-section of such a tire in the meridian plane is characterized in that, according to the European Tyre and Rim Technical Organization or "ETRTO" standard of 2019, the cross-section height H and the nominal cross-section width S satisfy a ratio H / S expressed as a percentage of at most equal to 90, preferably at most equal to 80, more preferably at most equal to 70, and at least equal to 30, preferably at least equal to 40, and the nominal cross-section width S is at least equal to 115 mm, preferably at least equal to 155 mm, more preferably at least equal to 175 mm, and at most equal to 385 mm, preferably at most equal to 315 mm, more preferably at most equal to 285 mm, even more preferably at most equal to 255 mm. In addition, the diameter D at the rim flange defines the diameter of the mounting rim of the tire, and this diameter D is at least equal to 12 inches, preferably at least equal to 16 inches, and at most equal to 24 inches, preferably at most equal to 20 inches.

[0037] The axial direction is understood as the direction that is substantially parallel to the main axis of the tire or the support member (i.e., the axis of rotation of the tire or the support member).

[0038] The circumferential direction is understood as the direction that is substantially perpendicular to both the axial direction and the radius of the tire or the support member at the same time (in other words, tangent to the circle centered on the axis of rotation of the tire or the support member).

[0039] The radial direction is understood as the direction along the radius of the tire or the support member, that is, any direction that intersects the axis of rotation of the tire or the support member and is substantially perpendicular to this axis.

[0040] The mid-plane of the tire (denoted by M) is understood as the plane perpendicular to the axis of rotation of the tire, which is axially midway between the two beads and passes through the axial middle of the crown reinforcement.

[0041] The mid-plane of the component (denoted by m) is understood as the plane perpendicular to the main axis of the support member, which is axially midway between each axial edge of the component.

[0042] The equatorial circumferential plane of the tire (denoted by E) is understood as such a theoretical cylindrical surface that passes through the equator of the tire and is perpendicular to the mid-plane and the radial direction. The equator of the tire is the axis in the meridian cross-sectional plane (the plane perpendicular to the circumferential direction and parallel to the radial direction and the axial direction), which is parallel to the axis of rotation of the tire and is equidistantly located between the radially outermost point of the tread designed to contact the ground and the radially innermost point of the tire designed to contact the support member (such as a rim), and the distance between these two points is equal to H.

[0043] The equatorial circumferential plane of the component (denoted by e) is understood as such a theoretical cylindrical surface that passes through the equator of the component and is perpendicular to the mid-plane and the radial direction. The equator of the component is the axis parallel to the main axis of the support member in the meridian cross-sectional plane (the plane perpendicular to the circumferential direction and parallel to the radial direction and the axial direction), which is equidistantly located between the radially outermost point and the radially innermost point of the component, and the distance between these two points is equal to h.

[0044] The meridian plane is understood as the plane that is parallel to the axis of rotation of the tire, contains this axis of rotation and is perpendicular to the circumferential direction.

[0045] The bead is understood as the part of the tire designed to enable the tire to be attached to a mounting support member (such as a wheel including a rim). Thus, each bead is especially designed to contact the flange of the rim so that it can be attached.

[0046] The main direction in which the filamentary reinforcing element extends is understood as the direction along which the filamentary reinforcing element extends along its maximum length. The main direction along which the filamentary reinforcing element extends can be straight or curved, and the reinforcing element can show a straight or wavy path along its main direction.

[0047] The portion of a component, layer or tire that is axially located between the axial edges of the component or layer or reinforcement is understood to be the portion that extends axially of the component, layer or tire and is located between radial planes that pass through the axial edges of the component or layer or reinforcement.

[0048] A portion of a component that is intended to extend axially, a portion of a component that extends axially, or a portion of a layer that extends axially radially aligned with a reference component or reference layer is understood to be the portion of the component or layer that is located between the radial projections on the component or layer of the axial edges of the reference component or reference layer.

[0049] Any numerical range represented by the expression "between a and b" represents a numerical range that extends from greater than a to less than b (i.e., excluding the end points a and b), while any numerical range represented by the expression "a to b" means a numerical range that extends from a up to and including b (i.e., including the strict end points a and b).

[0050] In a tire, the angle in question is an angle in absolute value and is the smaller of two angles defined between a reference line (in this case the circumferential direction of the tire) and the main direction along which the filamentary reinforcement element in question extends.

[0051] In a tire and in a method, the orientation of an angle is understood to be a clockwise or counterclockwise direction, where one must rotate from the reference line that defines the angle (in this case the circumferential direction of the support or tire) to reach the main direction along which the filamentary reinforcement element in question extends.

[0052] In a method, by convention, the angles formed by the main directions along which the working filamentary reinforcement elements and the carcass filamentary reinforcement elements extend are angles of opposite orientation, and the angle formed by the main direction along which each working filamentary reinforcement element extends is, in absolute value, the smaller of two angles defined between a reference line (in this case the circumferential direction of the support or tire) and the main direction along which the working filamentary reinforcement element extends. Thus, the angle formed by the main direction along which each working filamentary reinforcement element extends defines an orientation that is opposite to the orientation formed by the angle of the main direction along which each carcass filamentary reinforcement element extends.

[0053] In embodiments where there is slight industrial variability during the manufacture of one or more carcass plies, the absolute value of the angle A3 is from 85° to 90°, preferably substantially equal to 90°.

[0054] Preferably, the absolute value of the angle AT is from 30° to 37°, preferably from 30° to 35°. The inventors of the present invention have noticed that, compared with a smaller angle, by using a relatively large angle AT (i.e., an angle greater than or equal to 30°), the shear stiffness of the tire crown is improved.

[0055] However, using too large an angle AT (i.e., greater than 37°) will cause a reduction in the circumferential stiffness and an increase in tire noise. Therefore, it is preferred not to use too large an angle AT. Within the scope of the present invention, the inventors have recognized that using too large an angle AT reduces the contribution of the working layer to the circumferential stiffness due to a smaller projection of the forces generated by the working layer in the circumferential direction. In addition, still within the scope of the present invention, the inventors have recognized that, compared with a more moderate angle AT, too large an angle AT results in an increase in noise due to an increase in vibration response.

[0056] In embodiments that enable one or more carcass layers to be easily anchored in each bead, each bead includes a circumferential reinforcing element, after the step of arranging the carcass assembly and before the step of arranging the working assembly:

[0057] - Arrange two circumferential reinforcing elements around the carcass assembly,

[0058] - Axially turn each axial edge of the carcass assembly inwardly so that the carcass assembly axially winds around each circumferential reinforcing element.

[0059] In these embodiments where one or more carcass layers are wound around the circumferential reinforcing element, the carcass layer or each carcass layer is axially bounded by two axial edges of the carcass layer and includes carcass filamentary reinforcing elements extending axially from one axial edge of the carcass layer to the other axial edge, and the main direction of each carcass filamentary reinforcing element forms with the circumferential direction of the tire:

[0060] - An angle ACS with an absolute value strictly less than 80° in the axially central portion of the carcass layer that axially extends radially aligned with the working layer,

[0061] - An angle ACF with an absolute value of 80° to 90°, preferably 85° to 90 °C, more preferably substantially equal to 90° in each axial side portion of the carcass layer that axially extends between the axially central portion of the carcass layer and each axial edge, and each axial side portion winds around each circumferential reinforcing element.

[0062] In the above method, the initial angle formed by the main directions of the carcass filamentary reinforcing elements and the working filamentary reinforcing elements with the circumferential direction of the support varies during the deformation step to reach its final angle and the angle in the tire. Except for each axial side portion wound around the circumferential reinforcing element, the main direction of the carcass filamentary reinforcing elements in each axial side portion remains substantially the same with respect to the circumferential direction of the support and thus with respect to the circumferential direction of the tire.

[0063] Furthermore, by maintaining the initial angle A3 in each axial side portion and an angle ACS with an absolute value strictly less than 80° in the axial central portion, the tire has the performance of a radial tire conferred by the radial carcass filamentary reinforcing elements in the sidewall and the performance of a tire including a triangular crown reinforcing element.

[0064] In embodiments where there is a transition zone in which the main direction of each carcass filamentary reinforcing element can vary significantly between the axial central portion and the axial side portions, the axial width of the axial central portion is equal to at least 40%, preferably at least 50%, and equal to at most 90%, preferably at most 80%, of the axial width of the working layer. Preferably, the median plane of the tire intersects this axial central portion. More preferably, this axial central portion of the carcass layer or each carcass layer is axially centered on the median plane of the tire. The axial width of the axial central portion depends particularly on the degree of deformation and the initial angle. Those skilled in the art know how to vary the axial width of the axial central portion by changing one and / or the other of these parameters.

[0065] In these embodiments where there is a transition zone in which the main direction of each carcass filamentary reinforcing element can vary significantly between the axial central portion and the axial side portions, the radial height of each axial side portion is equal to at least 50% and equal to at most 100% of the radial height of the tire. Preferably, the equatorial circumferential plane of the tire intersects each axial side portion. Similarly to the axial central portion, the radial height of each axial side portion depends particularly on the degree of deformation and the initial angle. Those skilled in the art know how to vary the radial height of each axial side portion by changing one and / or the other of these parameters.

[0066] For most tire sizes for passenger vehicles, starting from an initial angle A3 with an absolute value of 80° to 90°, by obtaining an angle AT with an absolute value of 27° to 40°, the absolute value of the angle ACS is 50° to 75°.

[0067] According to the invention, when the absolute value of the initial angle A3 is between 80° and 90°, the axial part of the carcass filamentary reinforcing element present in the axial central part of the carcass assembly undergoes rotation, causing a decrease in the angle formed by its main direction. This decrease depends on the degree of deformation and on the initial angle formed by the main direction of each working filamentary reinforcing element and the circumferential direction of the support before the deformation step. The degree of deformation is determined in a manner known to those skilled in the art based on the axial approach of the axial edges of one or more carcass assemblies and on the radial expansion of the assembly between its cylindrical shape and its toroidal shape. In a manner known to those skilled in the art, the determination of the final angle with respect to the initial angle (and vice versa) depends on the degree of deformation, as illustrated in FR2797213 and FR1413102.

[0068] In an embodiment where each axial side part is wound around each circumferential reinforcing element, each axial side part of the carcass ply preferably comprises:

[0069] - an inner axial side part, which is axially arranged between the axial central part and each circumferential reinforcing element, in which the main direction of each carcass filamentary reinforcing element forms an angle ACF1 with the circumferential direction of the tyre,

[0070] - an outer axial side part, which is axially arranged between each circumferential reinforcing element and each axial edge of the carcass ply, in which the main direction of each carcass filamentary reinforcing element forms an angle ACF2 with the circumferential direction of the tyre, the orientation of which is opposite to that of angle ACF1, such that |ACF1 - ACF2 - 180| ≤ 20°, preferably |ACF1 - ACF2 - 180| ≤ 10°, more preferably |ACF1 - ACF2 - 180| is substantially zero. The inner axial side part is axially arranged inside the outer axial side part.

[0071] Starting from the initial angle A3 according to the invention, the absolute value of each angle ACF1 and ACF2 is between 80° and 90°, preferably between 85° and 90°, more preferably substantially equal to 90°.

[0072] In order to obtain the angles ACS and ACF, a method is used in which a component having a substantially cylindrical shape is deformed so as to obtain a component having a substantially toroidal shape, such that after the deformation step, the main direction of each carcass filamentary reinforcing element forms:

[0073] - a final angle B3S, the absolute value of which is strictly less than 80°, in the axial central part of the carcass assembly that extends axially in radial alignment with the working assembly, the axial central part of the carcass assembly being intended to form the axial central part of the carcass ply,

[0074] - The final angle B3F has an absolute value of 80° to 90°, preferably 85° to 90°, more preferably substantially equal to 90° in two axial side portions of the carcass assembly. Each axial side portion extends axially between the axial central portion and each axial edge of the carcass assembly and each axial side portion is intended to form each axial side portion of the carcass ply.

[0075] In most embodiments, no step between the deformation step and the crosslinking step causes a change in the angle B3S. Thus, the final angle B3S is substantially equal to the angle ACS. Accordingly, the absolute value of B3S is 50° to 75°.

[0076] In other embodiments, during any step between the deformation step and the crosslinking step, for example during the step of molding the green form in a mold, the final angle B3S may decrease slightly. Compared to the deformation experienced during the deformation step, the green form undergoes non-negligible radial and circumferential molding deformations during the step of molding the green form.

[0077] In certain embodiments using a step between the deformation step and the crosslinking step, the method comprises the steps of:

[0078] - Molding a tire of a green form obtained from an assembly having a generally toroidal shape by radially and circumferentially expanding the green form,

[0079] - Crosslinking the expanded green form having a generally toroidal shape to obtain a tire.

[0080] Preferably, before the crosslinking step, a strip of polymeric material intended to form the tread is radially arranged on the outer side of the working assembly to form the green form.

[0081] To obtain the angle AT for most tire sizes for passenger vehicles, a method is used in which the working assembly is axially bounded by two axial edges of the working assembly and includes working filamentary reinforcing elements extending axially from one axial edge of the working assembly to the other axial edge substantially parallel to each other. Each working filamentary reinforcing element extends in the working assembly along the main direction of each working filamentary reinforcing element, and the main direction of each working filamentary reinforcing element forms an initial angle A2 of 25° to 50° with the circumferential direction of the support. Implicitly, the initial angle A2 is constant when moving axially from one axial edge of the working assembly to the other axial edge.

[0082] In most embodiments where no step between the shaping step and the crosslinking step causes a change in the final angle B2 formed between the main direction of each carcass filamentary reinforcing element and the circumferential direction of the support after the shaping step, the final angle B2 is substantially equal to the angle AT. Thus, the assembly having a generally cylindrical shape about the main axis of the support is shaped to obtain an assembly having a generally toroidal shape about the main axis of the support such that after the shaping step, the main direction of each working filamentary reinforcing element forms a final angle B2 with the circumferential direction of the support having an absolute value of from 27° to 40°, preferably from 30° to 37°, more preferably from 30° to 35°.

[0083] In one embodiment capable of manufacturing a tire including a hoop reinforcement radially disposed outside the working reinforcement, after the shaping step, a hoop assembly intended to form the hoop reinforcement is disposed radially around the assembly having a generally toroidal shape about the main axis of the support, the hoop assembly being formed by helically winding one or more hoop filamentary reinforcing elements or a hoop ply, wherein the hoop ply is obtained by embedding one or more hoop filamentary reinforcing elements in an elastomeric matrix.

[0084] During this method step, the step of disposing the hoop assembly is carried out such that the hoop filamentary reinforcing element or each hoop filamentary reinforcing element extends axially between the two axial edges of the hoop assembly along the main direction of the hoop filamentary reinforcing element or each hoop filamentary reinforcing element. The absolute value of the angle formed by the main direction of the hoop filamentary reinforcing element or each hoop filamentary reinforcing element and the circumferential direction of the support is advantageously less than or equal to 10°, preferably less than or equal to 7°, more preferably less than or equal to 5°.

[0085] Tire according to the present invention

[0086] A tire according to the invention is obtained using the method as defined above.

[0087] In embodiments capable of improving the performance of the tire (especially in terms of cornering stiffness and performance at high speeds), the tire includes a hoop reinforcement radially disposed outside the working reinforcement, the hoop reinforcement being axially delimited by two axial edges of the hoop reinforcement and including at least one hoop filamentary reinforcing element helically wound circumferentially so as to extend axially between the axial edges of the hoop reinforcement along a main direction forming an angle AF with the circumferential direction of the tire having an absolute value less than or equal to 10°, preferably less than or equal to 7°, more preferably less than or equal to 5°. The hoop reinforcement is radially inserted between the working reinforcement and the tread.

[0088] In a variant form, the carcass reinforcement comprises a single carcass ply. In this variant form, apart from the single carcass ply, the carcass reinforcement does not have any ply reinforced by filamentary reinforcement elements. The filamentary reinforcement elements of such reinforcement plies excluded from the carcass reinforcement of the tire include metallic filamentary reinforcement elements and fabric filamentary reinforcement elements. Very preferably, the carcass reinforcement consists of a single carcass ply.

[0089] In another variant form, the carcass reinforcement comprises two carcass plies, and the main directions of the carcass filamentary reinforcement elements of the two carcass plies are substantially parallel to each other.

[0090] In the tire according to the invention, the crown comprises a tread and a crown reinforcement. The tread is understood to be a strip of polymeric material, preferably a strip of elastomeric material, which is defined as follows:

[0091] - radially outwards by a surface intended to come into contact with the ground, and

[0092] - radially inwards by the crown reinforcement.

[0093] The strip of polymeric material consists of a ply of polymeric material, preferably a ply of elastomeric material, or consists of several stacked plies, each ply being made of polymeric material, preferably elastomeric material.

[0094] In an advantageous embodiment, the crown reinforcement comprises a single hoop reinforcement and a single working reinforcement. Thus, apart from the hoop reinforcement and the working reinforcement, the crown reinforcement does not have any reinforcement reinforced by filamentary reinforcement elements. The filamentary reinforcement elements of such reinforcements excluded from the crown reinforcement of the tire include metallic filamentary reinforcement elements and fabric filamentary reinforcement elements. Very preferably, the crown reinforcement consists of the hoop reinforcement and the working reinforcement.

[0095] In a very preferred embodiment, apart from the crown reinforcement, the crown does not have any reinforcement reinforced by filamentary reinforcement elements. The filamentary reinforcement elements of such reinforcements excluded from the crown of the tire include metallic filamentary reinforcement elements and fabric filamentary reinforcement elements. Very preferably, the crown consists of the tread and the crown reinforcement.

[0096] In a very preferred embodiment, the carcass reinforcement is arranged to be in direct radial contact with the crown reinforcement, and the crown reinforcement is arranged to be in direct radial contact with the tread. In this very preferred embodiment, the hoop reinforcement and the working ply are advantageously arranged to be in direct radial contact with each other.

[0097] The expression "radially in direct contact" means that the objects in question (in this case, the layers, reinforcements or treads) that are in direct contact with each other radially are not radially separated by any object, for example, not radially separated by any layer, reinforcement or strip that is radially inserted between the objects in question that are in direct contact with each other radially.

[0098] To better ensure an effective triangulation of the tyre crown, in the part of the tyre axially located between the axial edges of the working layer and the axially narrowest layer or reinforcement in the hoop reinforcement, the principal directions of the hoop filamentary reinforcement elements or each hoop filamentary reinforcement element, the principal directions of each working filamentary reinforcement element and the principal directions of each carcass filamentary reinforcement element form pairs of angles with different absolute values with respect to the circumferential direction of the tyre. This is also referred to as the triangular grid formed by the hoop filamentary reinforcement elements, the working filamentary reinforcement elements and the carcass filamentary reinforcement elements.

[0099] In other words, the hoop filamentary reinforcement elements or each hoop filamentary reinforcement element extends along the principal hoop direction, each working filamentary reinforcement element extends along the principal working direction, and each carcass filamentary reinforcement element extends along the principal carcass direction. In the part of the tyre axially delimited by the axial edges of the working layer and the axially narrowest layer or reinforcement in the hoop reinforcement, these hoop directions, working directions and carcass directions are pairwise different.

[0100] To further improve the triangulation of the tyre crown, in the part of the tyre axially located between the axial edges of the working layer, the principal directions of each working filamentary reinforcement element and the principal directions of each carcass filamentary reinforcement element form angles with opposite orientations with respect to the circumferential direction of the tyre.

[0101] Advantageously, the filamentary reinforcement elements of each layer are embedded in an elastomeric matrix. Different layers may contain the same or different elastomeric matrices.

[0102] An elastomeric matrix means a matrix that exhibits elastomeric properties in the crosslinked state. Such a matrix is advantageously obtained by crosslinking a composition comprising at least one elastomer and at least one other component. Preferably, the composition comprising at least one elastomer and at least one other component comprises an elastomer, a crosslinking system and a filler. The compositions used for these layers are conventional compositions for calendering reinforcements, which are generally based on natural rubber or some other diene elastomer, reinforcing fillers (such as carbon black), a vulcanization system and conventional additives. The adhesion between the filamentary reinforcement elements and the matrix in which they are embedded is ensured, for example, by a conventional adhesive composition (such as an RFL-type adhesive or an equivalent adhesive).

[0103] Advantageously, each working filamentary reinforcing element is a metal. A metal filamentary element is understood by definition to be a filamentary element formed from a single basic filament or a assembly having multiple basic filaments, where the basic filament is made entirely (100% of the filaments) of a metallic material. Such a metal filamentary element is preferably implemented with one or more filaments made of steel, which filaments are more preferably made of pearlitic (or ferritic-pearlitic) carbon steel (hereinafter referred to as "carbon steel"), or made of stainless steel (defined as a steel containing at least 11% chromium and at least 50% iron). However, of course, it is possible to use other steels or other alloys. When carbon steel is advantageously used, its carbon content (weight % of the steel) is preferably from 0.05% to 1.2%, particularly from 0.5% to 1.1%; these contents represent a good compromise between the mechanical properties required for the tire and the availability of the filaments. The metal or steel used, whether it is particularly carbon steel or stainless steel, can itself be coated with a metal layer, which metal layer, for example, improves the processability of the metal cord and / or its constituent elements, or improves the wear properties of the cord and / or the tire itself, such as grip, corrosion resistance or anti-aging properties. According to a preferred embodiment, the steel used is coated with a layer of brass (Zn-Cu alloy) or a layer of zinc. As described above, each metal basic filament is preferably made of carbon steel and has a mechanical strength of from 1000 MPa to 5000 MPa. Such mechanical strength corresponds to the common steel grades in the tire field, namely NT (Normal Tensile), HT (High Tensile), ST (Higher Tensile), SHT (Super High Tensile), UT (Ultra Tensile), UHT (Ultra High Tensile) and MT (Massive Tensile) grades. The use of high mechanical strength potentially allows for improved reinforcement of the matrix intended to be embedded with the cord and can lighten the matrix thus reinforced. The assembly of the single basic filament or multiple basic filaments can be coated with a polymeric material, for example as described in US20160167438.

[0104] It will be readily understood from the foregoing general description and the following description of the drawings that the angles AT, ACS, ACF, ACF1, ACF2 and AF characterize the angles in the final tire, the angles A1, A2, A3 characterize the angles before the deformation step, and the angles B2, B3S, B3F characterize the angles after the deformation step and before the crosslinking step. Description of the Drawings

[0105] Description of the embodiments

[0106] According to the following detailed description and non-limiting exemplary embodiments and those related to these examples Figures 1 to 14 it will be readily understood the present invention and its advantages, wherein:

[0107] - Figure 1 is a cross-sectional view in the meridional plane of a tire according to the present invention;

[0108] - Figure 2 A Figure 1 schematic cross-sectional view of a tire, showing an arrangement in which filamentary reinforcing elements are radially aligned with the working layer and vertically radially aligned above the working layer;

[0109] - Figure 3 A Figure 1 schematic view of carcass filamentary reinforcing elements arranged in the sidewall of a

[0110] - Figure 4 A Figure 1 view of a part of the tire crown of a

[0111] - Figures 5 to 14 Shows different steps of a method for manufacturing a Figure 1 tire according to the present invention. DETAILED DESCRIPTION

[0112] In the figures related to the tire, a reference system X, Y, Z is shown, which respectively correspond to the usual circumferential direction (X), axial direction (Y) and radial direction (Z) of the tire. In the figures related to the method, a reference system x, y, z is shown, which respectively correspond to the usual circumferential direction (x), axial direction (y) and radial direction (z) of the manufacturing support, which can deform between a generally cylindrical shape and a toroidal shape around the axis y.

[0113] Figure 1 A tire 10 according to the present invention is shown, denoted by the overall reference numeral 10. The tire 10 exhibits substantially rotational symmetry about an axis that is substantially parallel to the axial direction Y. The tire 10 is in this case intended for a passenger vehicle and has the size 245 / 45R18.

[0114] The tire 10 includes a crown 12, the crown 12 including a tread 20 intended to contact the ground during operation and a crown reinforcement 14 extending in the circumferential direction X in the crown 12. The tire 10 also includes an airtight layer 15 for the inflation gas, which is intended to delimit a closed internal cavity with the mounting support for the tire 10 once the tire 10 has been mounted on the mounting support (such as a rim).

[0115] The crown reinforcement 14 includes a single working reinforcement 16 containing a working layer 18, and a single hoop reinforcement 17 containing a single hoop layer 19. In this case, the working reinforcement 16 includes a single working layer 18 and, in this particular case, consists of a single working layer 18. In the following description, for reasons of simplicity, reference will be made to the working layer 18 without reiterating each time that this layer is a single layer. The hoop reinforcement 17 consists of the hoop layer 19.

[0116] The crown reinforcement 14 is covered radially by the tread 20. In this case, the hoop reinforcement 17 (in this case the hoop ply 19) is arranged radially outside the working reinforcement 16 and is thus radially inserted between the working reinforcement 16 and the tread 20. In Figure 1 and Figure 2 the illustrated embodiment, the axial width of the hoop reinforcement 17 is less than the axial width of the working ply 18. Thus, the hoop reinforcement 17 is the narrower one axially among the working ply 18 and the hoop reinforcement 17.

[0117] The tire 10 includes two sidewalls 22 that extend the crown 12 radially inwardly. The tire 10 also has two beads 24 located radially inside the sidewalls 22. Each sidewall 22 connects each bead 24 to the crown 12 respectively.

[0118] Each bead 24 includes at least one circumferential reinforcement element 26, which in this case includes a bead wire 28 covered radially by a filling rubber block 30.

[0119] The tire 10 includes a carcass reinforcement 32 anchored in each bead 24. The carcass reinforcement 32 extends in each sidewall 22 and radially inside the crown 12. The crown reinforcement 14 is arranged radially between the tread 20 and the carcass reinforcement 32.

[0120] The carcass reinforcement 32 includes a carcass ply 34. In this case, the carcass reinforcement 32 includes a single carcass ply 34 and, in this particular case, consists of a single carcass ply 34. In this embodiment, for reasons of simplicity, the carcass ply 34 will be referred to and it will not be reiterated each time that this ply is a single ply.

[0121] The carcass reinforcement 32 is arranged to be in direct radial contact with the crown reinforcement 14. The crown reinforcement 14 is arranged to be in direct radial contact with the tread 20. The hoop reinforcement 17 and the working ply 18 are arranged to be in direct radial contact with each other.

[0122] Now reference will be made to Figures 1 to 4 describe the hoop ply 19, the working ply 18 and the carcass ply 34.

[0123] The hoop reinforcement 17 (in this case, the hoop ply 19) is axially bounded by two axial edges 17A, 17B of the hoop reinforcement 17. The hoop reinforcement 17 includes a plurality of hoop filamentary reinforcing elements 170 that are helically wound circumferentially and extend axially between the axial edge 17A and the other axial edge 17B of the hoop ply 17 along the main direction D1 of each hoop filamentary reinforcing element 170. The main direction D1 forms an angle AF with the circumferential direction X of the tire 10, where the absolute value of the angle AF is less than or equal to 10°, preferably less than or equal to 7°, and more preferably less than or equal to 5°. In this case, AF = -5°.

[0124] The working ply 18 is axially bounded by two axial edges 18A, 18B of the working ply 18. The working ply 18 includes working filamentary reinforcing elements 180 that extend axially from the axial edge 18A of the working ply 18 to the other axial edge 18B in a substantially parallel manner to each other. Each working filamentary reinforcing element 180 extends along the main direction D2 of each working filamentary reinforcing element 180. The direction D2 forms an angle AT with the circumferential direction X of the tire 10, where the absolute value of the angle AT is strictly greater than 10°, preferably between 27° and 40°, preferably between 30° and 37°, and more preferably between 30° and 35°. In this case, AT = -35°.

[0125] The carcass ply 34 is axially bounded by two axial edges 34A, 34B of the carcass ply 34. The carcass ply 34 includes carcass filamentary reinforcing elements 340 that extend axially from the axial edge 34A of the carcass ply 34 to the other axial edge (not shown). The carcass ply 34 includes an axially central portion 34S and two axially side portions 34F. The axially central portion 34S extends axially in radial alignment with the working ply 18. The two axially side portions 34F extend axially between the axially central portion 34S and the respective axial edges 34A, 34B. Each axially side portion 34F is wound around each circumferential reinforcing element 26. Each axially side portion 34F includes an inner axially side portion 38 and an outer axially side portion 40. The inner axially side portion 38 is axially disposed between the axially central portion 34S and each circumferential reinforcing element 26. The outer axially side portion 40 is axially disposed between each circumferential reinforcing element 26 and each axial edge 34A, 34B of the carcass ply 34. The filler rubber block 30 is inserted between the inner axially side portion 38 and the outer axially side portion 40.

[0126] In the axial central portion 34S of the carcass ply 34, each carcass filament reinforcing element 340 extends along the main direction D3 of each carcass filament reinforcing element 340, and the main direction D3 forms an angle ACS with an absolute value strictly less than 80° with the circumferential direction X of the tire 10. Advantageously, in this axial central portion 34S of the carcass ply 34, the main direction D3 of each carcass filament reinforcing element 340 forms an angle ACS with an absolute value of 50° to 75° with the circumferential direction X of the tire 10. In this case, ACS = +65°.

[0127] The axial width of the axial central portion 34S of the carcass ply 34 is equal to at least 40%, preferably at least 50% and at most 90%, preferably at most 80% of the axial width L of the working ply 18, and in this particular case is equal to 60% of the axial width L of the working ply 18. The median plane M of the tire 10 intersects this portion 34S. More preferably, this portion 34S is axially centered on the median plane M of the tire 10.

[0128] As Figure 1 and Figure 3 As shown, in each axial side portion 34F of the carcass ply 34 that extends radially in each sidewall 22, the main direction D3 of each carcass filament reinforcing element 340 forms an angle ACF with an absolute value of 80° to 90°, preferably 85° to 90°, more preferably substantially equal to 90° with the circumferential direction X of the tire 10. In this case, ACF = +90°.

[0129] Each portion 34F of the carcass ply 34 that extends radially in each sidewall 22 has a radial height equal to at least 50% and at most 100% of the radial height H of the tire 10, and in this particular case is equal to 95% of the radial height H of the tire 10. The equatorial circumferential plane E of the tire 10 intersects each portion 34F of the carcass ply 34 located in each sidewall 22.

[0130] The main direction D3 of each carcass filament reinforcing element 340 forms an angle ACF1 with the circumferential direction X of the tire 10 in each inner axial side portion 38 and an angle ACF2 in each outer axial side portion 40. The angles ACF1 and ACF2 have opposite orientations. The absolute value of each of the angles ACF1 and ACF2 is 80° to 90°, preferably 85° to 90°, more preferably substantially equal to +90° and -90° respectively. Note that |ACF1 - AFC2 - 180| ≤ 20°, preferably |ACF1 - ACF2 - 180| ≤ 10°, and in this case |ACF1 - ACF2 - 180| is substantially zero.

[0131] As Figure 2As shown, in the portion PS of the tire 10 that is axially located between the axial edges 18A, 18B of the working ply 18, the main direction D2 of each working filamentary reinforcing element 180 and the main direction D3 of each carcass filamentary reinforcing element 340 form angles AT and ACS with opposite orientations with respect to the circumferential direction X of the tire 10. Specifically, in this case, AT = -35° and ACS = +65°. Additionally, in the portion PS' of the tire 10 that is axially located between the axial edges 17A, 17B of the hoop reinforcement 17, the main direction D1 of each hoop filamentary reinforcing element 170, the main direction D2 of each working filamentary reinforcing element 180, and the main direction D3 of each carcass filamentary reinforcing element 340 form pairs of angles with different absolute values with respect to the circumferential direction X of the tire 10.

[0132] Generally, and particularly in the described embodiments, each portion PS, PS' of the tire 10 has an axial width that is equal to at least 40%, preferably at least 50% and equal to at most 90%, preferably at most 80% of the axial width L of the working ply 18, and in this particular case is equal to 60% of the axial width L of the working ply 18. The median plane M of the tire 10 intersects each portion PS, PS' of the tire 10. More preferably, each portion PS, PS' of the tire 10 is axially centered on the median plane M of the tire 10.

[0133] Each working filamentary reinforcing element 180 is a assembly of two steel monofilaments, each steel monofilament having a diameter equal to 0.30 mm, and the two steel monofilaments are wound together with a lay length of 14 mm.

[0134] Each carcass filamentary reinforcing element 340 generally comprises two multifilament strands, each multifilament strand being formed by the spinning of polyester (PET in this case) monofilaments. These two multifilament strands are each overtwisted at 240 turns per meter in one direction and then twisted together at 240 turns per meter in the opposite direction. These two multifilament strands are helically wound around each other. Each of these multifilament strands has a yarn count equal to 220 tex.

[0135] Each hoop filamentary reinforcing element 170 is of the types described, for example, in WO2016 / 166056A1.

[0136] The tire 10 is obtained by a method according to the present invention, and the method will be described with reference to Figures 5 to 14 to describe the method.

[0137] First, the winding working component 50 and the carcass component 52 are obtained as follows: The filamentous reinforcing elements 180 and 340 of each of the components 50 and 52 are arranged parallel to each other and then embedded, for example by surface coating, in an uncrosslinked composition comprising at least one elastomer, which composition is intended to form an elastomeric matrix after crosslinking. A ply called a straight ply is obtained, in which the filamentous reinforcing elements are parallel to each other and parallel to the main direction of the ply.

[0138] Next, for the working ply, sections of the straight working ply are cut at a cutting angle and these sections are butt-jointed to each other to obtain a working ply called an angled working ply, in which the working filamentous reinforcing elements are parallel to each other and form an angle equal to the cutting angle with the main direction of the working ply.

[0139] For the carcass ply, sections of the straight carcass ply are cut perpendicular to the main direction of the straight carcass ply and these sections are butt-jointed to each other to obtain a carcass ply called an angled carcass ply, in which the carcass filamentous reinforcing elements are parallel to each other and form an angle equal to the cutting angle with the main direction of the carcass ply, which angle is from 80° to 90°.

[0140] In the described embodiment, a single working ply 49 and a single carcass ply 51 are obtained, the respective axial widths of which (i.e., the dimensions along the direction perpendicular to the longitudinal edges of each ply) are equal to the respective axial widths of the working component 50 and the carcass component 52 that will subsequently be formed.

[0141] Reference Figure 5 , in the first step of assembling the green tire, the sealing ply 70 is arranged around the support 60 so as to form a sealing assembly 72 intended to form the sealing layer 15, wherein the support 60 has a generally cylindrical shape around its main axis A. In this case, the sealing ply 70 is arranged by winding the sealing ply 70. The support 60 has a generally cylindrical laying surface with a radius equal to 235 mm.

[0142] Next, reference Figure 6, radially outside the seal assembly 72, a carcass assembly 52 is arranged around the support member 60 and is intended to form the carcass ply 34. In this particular case, the carcass assembly 52 is arranged by winding the carcass ply 51 around the support member 60, thereby forming the carcass assembly 52. The carcass assembly 52 is axially bounded by two axial edges 52A, 52B of the carcass assembly 52 and includes carcass filamentary reinforcing elements 340 that extend axially from the axial edge 52A of the carcass assembly 52 to the other axial edge 52B and are substantially parallel to each other. Each carcass filamentary reinforcing element 340 extends in the carcass assembly 51 along the main direction K3 of each carcass filamentary reinforcing element 340 of the carcass assembly 52. The main direction K3 forms an initial angle A3 with the circumferential direction x of the support member 60, and the absolute value of each carcass filamentary reinforcing element 340 is 80° to 90°, preferably 85° to 90°, and in this case is substantially equal to 90°.

[0143] Reference Figure 7 and Figure 8 , next, two circumferential reinforcing elements 26 are arranged around the carcass assembly 52, and each axial edge 52A, 52B of the carcass assembly 52 is axially turned inward, so that each circumferential reinforcing element 26 is radially covered by each axial edge 52A, 52B of the carcass assembly 52, and the carcass assembly 52 is axially wound around each circumferential reinforcing element 26.

[0144] Figure 9 The illustration shown shows the arrangement of the carcass filamentary reinforcing elements 340 after the step of axially turning the axial edges 52A, 52B of the carcass assembly 52 around the circumferential reinforcing element 26. In this Figure 9 the above-mentioned initial angle A3 is shown.

[0145] Next, reference Figure 10 , radially outside the carcass assembly 52, a working assembly 50 is arranged and is intended to form the working layer 18. In this particular case, the working assembly is arranged by winding the working ply 49 radially outside the carcass assembly 52, thereby forming the working assembly 50. The working assembly 50 is axially bounded by two axial edges 50A, 50B of the working assembly 50 and includes working filamentary reinforcing elements 180 that extend axially from the axial edge 50A of the working assembly 50 to the other axial edge 50B and are substantially parallel to each other. Each working filamentary reinforcing element 180 extends in the working assembly 50 along the main direction K2 of each working filamentary reinforcing element 180 of the working assembly 50. Reference Figure 11 , the main direction K2 forms an initial angle A2 with the circumferential direction x of the support member 60, and the absolute value of each working filamentary reinforcing element 180 is 25° to 50°. In this case, A2 = -39°.

[0146] Thus, the carcass assembly 52 and the working assembly 50 form an assembly 58 having a generally cylindrical shape about the main axis A of the support member 60.

[0147] Figure 11 A figure similar to Figure 9 is shown, which shows the arrangement of the carcass filamentary reinforcing elements 340 and the working filamentary reinforcing elements 180 after the step of forming the working assembly 50. The initial angles A2 and A3 are shown in this Figure 11 .

[0148] Next, the assembly 58 having a generally cylindrical shape about the main axis A of the support member 60 is deformed to obtain an assembly 58 having a generally toroidal surface shape about the main axis A of the support member 60. The deformed assembly 58 shown in Figure 12 is obtained. The laying surface of the support member 60 then has a radius equal to 327 mm in the mid-plane of the support member.

[0149] Referring to Figure 13 , the assembly 58 having a generally cylindrical shape about the main axis A of the support member 60 is deformed to obtain an assembly 58 having a generally toroidal surface shape about the main axis A of the support member 60, such that after the deformation step, in the axial central portion 52S of the carcass assembly 52 that axially extends radially aligned with the working assembly 50, the main direction K3 of each carcass filamentary reinforcing element 340 forms a final angle B3S with the circumferential direction x of the support member 60, the absolute value of which for each carcass filamentary reinforcing element 340 is strictly less than 80°. Advantageously, the absolute value of the final angle B3S is between 50° and 75°. In this case, B3S = +65°. The portion 52S of the carcass assembly 52 is intended to form the axial central portion 34S of the carcass layer 34.

[0150] The assembly 58 having a generally cylindrical shape about the main axis A of the support member 60 is deformed to obtain an assembly 58 having a generally toroidal surface shape about the main axis A of the support member 60. Similarly, after the deformation step, in the two axial side portions 52F of the carcass assembly 52 that axially extend respectively between the axial central portion 52S and the respective axial edges 52A, 52B of the carcass assembly 52, the main direction K3 of each carcass filamentary reinforcing element 340 forms a final angle B3F with the circumferential direction x of the support member 60, the absolute value of which for each carcass filamentary reinforcing element 340 is between 80° and 90°. Each axial side portion 52F of the carcass assembly 52 is intended to form each axial side portion 34F of the carcass layer 34. In this case, B3F = +90°.

[0151] Deform the component 58 that has a generally cylindrical shape about the main axis A of the support member 60 so as to obtain a component 58 that has a generally toroidal surface shape about the main axis A of the support member 60. Similarly, such that after the deformation step, the main direction K2 of each working filamentary reinforcing element 340 forms a final angle B2 with the circumferential direction x of the support member 60, the absolute value of which for each working filamentary reinforcing element 340 is strictly greater than 10°. Advantageously, the absolute value of the final angle B2 is from 27° to 40°, preferably from 30° to 37°, more preferably from 30° to 35°, and in this case B2 = -35°.

[0152] In the portion AC of the component 58 that is axially located between the axial edges 50A, 50B of the working component 50, the main direction K2 of each working filamentary reinforcing element 180 and the main direction K3 of each carcass filamentary reinforcing element 340 form final angles B2 and B3S with the circumferential direction x of the support member 60 that are opposite in orientation. Specifically, in this case, B2 = -35° and B3S = +65°.

[0153] As Figure 14 shown, a hoop assembly 76 intended to form a hoop reinforcement 17 is arranged radially around the component 58 previously formed on the support member 60. In this case, the hoop assembly 76 is formed by helically winding a hoop ply 75 around the toroidal surface shape and then transferring the hoop assembly 76 to the radially outer side of the previously formed component 58 by means of a transfer ring. In a variant form, the hoop ply 74 can be helically wound circumferentially directly around the previously formed component 58 to form the hoop assembly 76. Similar to the carcass ply 51 and the working ply 49, the hoop ply 74 is made by embedding hoop filamentary reinforcing elements 170 in an elastomeric matrix.

[0154] In the illustrated embodiment, the axial width of the hoop assembly 76 is less than the axial width of the working component 50. Thus, the hoop assembly 74 is the narrower one axially among the working component 50 and the hoop assembly 76.

[0155] The step of arranging the hoop assembly 76 is carried out such that each hoop filamentary reinforcing element 170 extends axially between the two axial edges 76A, 76B of the hoop assembly 76 along the main direction K1 of each hoop filamentary reinforcing element 170. The absolute value of the angle formed by the main direction K1 of each hoop filamentary reinforcing element 170 and the circumferential direction x of the support member 60 is advantageously less than or equal to 10°, preferably less than or equal to 7°, more preferably less than or equal to 5°.

[0156] The absolute value of the angle A1 formed by the main direction K1 of each hoop filamentary reinforcing element 170 and the circumferential direction x of the support member 60 is less than or equal to 10°, preferably less than or equal to 7°, more preferably less than or equal to 5°, and in this case is equal to 5°.

[0157] In a portion AC' (not shown) of the component 58 and the hoop component 76 that is axially located between the axial edges 76A, 76B of the hoop component 76, the principal directions K1 of each hoop filamentary reinforcing element 170, the principal directions K2 of each working filamentary reinforcing element 180, and the principal directions K3 of each carcass filamentary reinforcing element 340 form pairs of angles with different absolute values with respect to the circumferential direction x of the support 60.

[0158] Next, radially outside the working component 50, in this case radially outside the hoop component 76, a strip of polymer material intended to form the tread 20 is arranged, thus forming a green tire 10 in the form of a green blank.

[0159] In a preferred variant form not shown, the hoop component 76 can be arranged in the form of a toroidal surface, and then a strip of polymer material intended to form the tread 20 can be arranged radially outside the hoop component 76, thus forming an intermediate component, and then this intermediate component can be transferred to the radial outside of the component 58 previously formed on the support 60.

[0160] Next, the green tire 10 in the form of a green blank obtained from the previously formed component 58, the hoop component 76, and the strip of polymer material is molded by radially and circumferentially expanding the green blank form.

[0161] Next, the expanded green blank form having a substantially toroidal surface shape is crosslinked, for example, by vulcanization, thus obtaining the tire 10.

[0162] Comparative test

[0163] The circumferential stiffness Rxx and the shear stiffness Gxy of different tires T1 and T2 not according to the present invention and tires P1, P2, P3, P4, P5 according to the present invention were simulated. The results are indicated on a scale of 100, such that values greater than 100 for the circumferential stiffness Rxx and the shear stiffness Gxy represent an improvement in these stiffnesses.

[0164] Tire T1 is tire S2 described in EP3489035. Tire P3 is the above-mentioned tire 10. All tires are the same except for the angles A3, A2, ACS, and AT, and the values of these angles are tabulated in Table 1 below.

[0165] Table 1

[0166]

[0167]

[0168] As described above, the angles AT and ACS have little influence on the circumferential stiffness Rxx. The shear stiffness Gxy is either slightly affected (tires P1 and P5) or improved for larger angles AT (tires P2, P3, and P4). Nevertheless, tires P1 to P5 have the undeniable advantage that all tires are made from a single carcass ply in which the angle A3 is between 80° and 90°, which does not require a step of cutting at a specific angle depending on the size of the tire.

[0169] The invention is not limited to the embodiments described above.

[0170] Specifically, it is easily conceivable to have a tire similar to the above-described tire and in which the carcass reinforcement includes two carcass plies.

[0171] The invention can also be implemented without a carcass ply including an axial side portion wound around each circumferential reinforcing element. In fact, other ways of anchoring the carcass ply 34 are feasible, such as those described in US5702548.

Claims

1. A method for manufacturing a tire, the tire comprising a crown, two sidewalls and two beads, each sidewall connecting each bead to the crown respectively, the tire comprising carcass reinforcement anchored in each bead, the carcass reinforcement extending in each sidewall and radially inside the crown, the carcass reinforcement comprising at least one carcass ply, the crown comprising: - a tread intended to come into contact with the ground during the operation of the tire, - a crown reinforcement radially arranged between the tread and the carcass reinforcement, the crown reinforcement comprising a working reinforcement having a single working ply, the working ply being axially delimited by two axial edges of the working ply and comprising working filamentary reinforcement elements, the working filamentary reinforcement elements extending axially from one axial edge of the working ply to the other axial edge substantially parallel to each other along the main direction of each working filamentary reinforcement element, the main direction of each working filamentary reinforcement element forming an angle AT with the circumferential direction of the tire, wherein, in the method: - a carcass assembly intended to form at least one carcass ply is arranged around a support, the support having a substantially cylindrical shape around a main axis, the carcass assembly being axially delimited by two axial edges of the carcass assembly and comprising carcass filamentary reinforcement elements, the carcass filamentary reinforcement elements extending axially from one axial edge of the carcass assembly to the other axial edge substantially parallel to each other, each carcass filamentary reinforcement element extending in the carcass assembly along the main direction of each carcass filamentary reinforcement element, the main direction of each carcass filamentary reinforcement element forming an initial angle A3 with the circumferential direction of the support, - a working assembly intended to form the working ply is arranged radially outside the carcass assembly, the carcass assembly and the working assembly forming an assembly having a substantially cylindrical shape around the main axis of the support, - in a deformation step, the assembly having a substantially cylindrical shape around the main axis of the support is deformed so as to obtain an assembly having a substantially toroidal shape around the main axis of the support, - the green tire obtained from the assembly having a substantially toroidal shape is crosslinked so as to obtain the tire, characterized in that the absolute value of the angle AT is between 30° and 37°, the absolute value of the initial angle A3 is substantially equal to 90°, and during the deformation step, the angle formed by the main direction of each carcass filamentary reinforcement element with the circumferential direction of the support has the following characteristics: - by rotating an axial portion of the carcass filamentary reinforcement element present in the axial central portion of the carcass assembly, in the axial central portion of the carcass assembly extending axially radially aligned with the working assembly, the angle decreases relative to the absolute value of the initial angle A3, and - the angle remains substantially the same as the initial angle A3 in the two axial side portions of the carcass assembly, each axial side portion extending axially between the axial central portion of the carcass assembly and each axial edge.

2. The method according to claim 1, wherein, the absolute value of the angle AT is between 30° and 35°.

3. The method according to claim 1, wherein, Each bead includes a circumferential reinforcing element, and wherein, after arranging the carcass assembly around the support member and before arranging the working assembly radially outside the carcass assembly: - Two circumferential reinforcing elements are arranged around the carcass assembly, and - Each axial edge of the carcass assembly is axially turned inwards so that the carcass assembly is axially wound around each circumferential reinforcing element.

4. The method according to claim 3, wherein, The carcass ply is axially bounded by two axial edges of the carcass ply and includes carcass filamentary reinforcing elements that axially extend from one axial edge of the carcass ply to the other axial edge, and wherein the main direction of each carcass filamentary reinforcing element forms with the circumferential direction of the tire: - An angle ACS with an absolute value strictly less than 80° in the axially central portion of the carcass ply that extends axially in radial alignment with the working ply, and the axially central portion of the carcass ply is formed by the axially central portion of the carcass assembly, and - An angle ACF with an absolute value substantially equal to 90° in each of the two axially side portions of the carcass ply that axially extend between the axially central portion of the carcass ply and the respective axial edges, each of the two axially side portions of the carcass ply is formed by two axially side portions of the carcass assembly, and each axially side portion of the carcass ply is wound around each circumferential reinforcing element.

5. The method according to claim 4, wherein, The absolute value of the angle ACS is from 50° to 75°.

6. The method according to claim 4 or 5, wherein, After the deformation step, the main direction of each carcass filamentary reinforcing element forms with the circumferential direction of the support member: - A final angle B3S with an absolute value strictly less than 80° in the axially central portion of the carcass assembly, and - A final angle B3F with an absolute value substantially equal to 90° in the two axially side portions of the carcass assembly.

7. The method according to claim 1, wherein, The working assembly is axially bounded by two axial edges of the working assembly and includes working filamentary reinforcing elements that axially extend from one axial edge of the working assembly to the other axial edge substantially parallel to each other, and wherein each working filamentary reinforcing element extends in the working assembly along the main direction of each working filamentary reinforcing element, and the main direction of each working filamentary reinforcing element forms an initial angle A2 with an absolute value of 25° to 50° with the circumferential direction of the support member.

8. The method according to claim 7, wherein, After the deformation step, the main direction of each working filamentary reinforcing element forms a final angle B2 with an absolute value of 27° to 40° with the circumferential direction of the support member.

9. A tire obtained by the method according to claim 1.

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