Method for manufacturing tyres of multiple dimensions

Abstract

The invention relates to a method for manufacturing tyres, comprising manufacturing a first tyre and manufacturing a second tyre of different dimensions, wherein the bead cores (8) are placed with the same distance between bead cores. During a shaping step, when the radial expansion of the central portion of the carcass ply (4) reaches an intervention diameter strictly less than the formation diameter, a triangulation member (10) is placed in contact with the carcass ply (4) in order to modify the orientation of the carcass reinforcements (6) during a next period of shaping, said triangulation member (10) being provided with parallel reinforcements (12) forming a non-zero angle (β) with the circumferential direction and the initial direction of the carcass ply reinforcements, the intervention diameter and / or the triangulation member being different during the manufacture of the first tyre and during the manufacture of the second tyre.

Description

[0001] Process for manufacturing tires of various sizes

[0002] Technical field

[0003] The invention belongs to the field of vehicle tires, and more specifically relates to a method for manufacturing tires of different dimensions (different sidewall heights, and / or different axial widths) from the same initial inter-bead distance.

[0004] 1Technological background

[0005] I 0

[0006] By convention, we consider a reference (O, OX, OY, OZ), the center O of which coincides with the center of the tire, the circumferential OX, axial OY, and radial OZ directions respectively designate a direction tangent to the rolling surface of the tire according to the direction of rotation, a direction parallel to the axis of rotation of the tire, and a direction orthogonal to the axis of rotation of the tire.

[0007] By radially inner, respectively radially outer, is meant closer, respectively further from the axis of rotation of the tire. By axially inner, respectively axially outer, is meant closer, respectively further from the equatorial plane of the tire, the equatorial plane of the tire being the plane passing through the

[0008] 10 middle of the tire tread and perpendicular to the tire's axis of rotation.

[0009] The constitution of the tire is usually described by a representation of its constituents in a meridian plane, that is to say a plane containing the axis of rotation of the tire. Such a choice is motivated by the axisymmetry of the geometry of the tire 15 around its axis of rotation. The tire also includes a plane of symmetry orthogonal to the axis of rotation and passing through the center of the tread: this is the equatorial plane.

[0010] It is customary to divide the tire into three distinct zones comprising a crown, intended to come into contact with the ground via a tread, a bead zone ensuring the mechanical connection of the tire to the rim on which it is mounted.

[0011] 10 intended to be mounted, and a flank zone intended to form the junction between the two axial ends of the crown and the beads of the heel zone.

[0012] A radial tire comprises a crown reinforcement, radially inside the tread, and a carcass reinforcement, radially inside the crown reinforcement. The crown reinforcement of a radial tire comprises a superposition of crown layers extending circumferentially, radially outside the carcass reinforcement. Each crown layer is made up of reinforcements parallel to each other and coated with a polymeric material of the elastomer type or elastomeric mixture.

[0013] 5 The carcass ply comprises a main part, connecting the two beads together and wrapping, in each bead, around an annular reinforcing structure, also called a bead wire. The carcass ply comprises reinforcements in an elastomeric mixture.

[0014] By elastomeric mixture is meant an elastomeric material obtained by mixing its various constituents. An elastomeric mixture conventionally comprises an elastomeric matrix with at least one diene elastomer of natural or synthetic rubber type, at least one reinforcing filler of carbon black type and / or silica type, a crosslinking system most often based on sulfur, and protective agents. For certain applications, the elastomers considered may also comprise

[0015] 1 thermoplastics (TPE).

[0016] 15 Many developments have been made to modify the angle of the carcass reinforcement ply in the crown zone in order to give it properties allowing it to contribute to the formation of the crown reinforcement, in cooperation with another ply made up of reinforcement elements whose orientation angle relative to the circumferential direction would be; opposite sign to that made by the carcass reinforcement elements in the zone located below the

[0017] 10 summit. In the crown reinforcement area, the angles formed by the wires of the carcass reinforcement ply and by the crown reinforcement ply with respect to the circumferential direction are generally between 15° and 40°.

[0018] For example, this type of tire is described in patent FR 1 413 102. This tire comprises a carcass reinforcement made up of wires arranged radially or

[0019] 15 substantially radially in the heel area and in the flank area, and which have an orientation deviating substantially from the radial orientation over a part of the area where the crown reinforcement extends.

[0020] In support of these developments, numerous embodiments have been proposed. These methods exploit the properties offered by the effects of triangulation when two

[0021] 10 plies, previously superimposed and adhering to each other, have different and opposite angles with respect to a circumferential direction and are stretched in this same direction. This effect results in the reduction of the orientation of the angles of these plies with respect to the circumferential direction. A complete description of this so-called triangulation mechanism is given in publication FR 2 797 213. To achieve this triangulation, it is first necessary, as explained in patents FR 1 413 102 and EPI 623819 A1, to successively arrange on a manufacturing drum of substantially cylindrical shape one or more carcass reinforcement plies whose threads are oriented radially then to arrange a crown reinforcement ply 5 having threads oriented obliquely with respect to the carcass threads, to make these different plies adhere to each other to form what is conventionally called a carcass.Then, in a second step, the carcass is shaped on a shaping drum comprising a diaphragm, to form a tire blank of a substantially toroidal shape.

[0022] 10 During the shaping phase, during which a cylindrical tire blank is transformed into a toroidal tire blank, the increase in the diameter of the central part intended to constitute the crown zone amounts to stretching the crown reinforcement ply and the carcass reinforcement ply in the longitudinal direction or again in the circumferential direction, and to giving the carcass reinforcement cords located in this crown zone and the cords of the crown reinforcement ply angles having a lower absolute value.

[0023] Tires can have various dimensions, for example with different sidewall heights and / or different axial widths. In order to obtain these varied dimensions, it is now necessary to have carcass plies of different widths.

[0024] 10 axial, which implies having large stocks of carcass plies, and complicates the supply of workstations since the carcass plies supplied and mounted on the drum must correspond to those required for the desired dimensions of the tire. In addition, when mounting on the drum, it must be precisely adjusted with; a bead spacing value (the distance axially separating the beads) specific to each tire size. Thus, a change in size in the tire to be manufactured generally involves modifying the settings of the machine drum, which is a very long operation which immobilizes the machine and therefore reduces production time.

[0025] Presentation of the invention

[0026] 10 The invention therefore aims to limit as much as possible the occurrence of machine setting change operations in order to improve productivity, to simplify the storage and supply constraints of carcass plies, but while retaining a capacity to produce very varied tire dimensions. To this end, the invention proposes a method for manufacturing tires comprising the manufacture of a first tire and the manufacture of a second tire, the first tire and the second tire having different dimensions, the manufacture of the first tire and the manufacture of the second tire comprising the following steps:

[0027] 5 - placing a carcass ply on a cylindrical drum with an initial diameter, said carcass ply comprising carcass reinforcements extending between two axial end portions of the carcass ply surrounding a central portion of the carcass ply,

[0028] - installation of rods at each of the axial end portions of the carcass ply, the rods defining between them an inter-rod distance,

[0029] 10 - a step of shaping the tire by causing radial expansion of the central portion of the carcass ply until said carcass ply reaches a constitution diameter,

[0030] - a step of constituting the tire comprising the placement, on a radially external face of the carcass ply, of at least one crown ply provided with reinforcements

[0031] 15 parallels forming a non-zero angle with the circumferential direction and the direction of the reinforcements of the carcass ply, and the installation of a tread, in which during the manufacture of the first tire and the manufacture of the second tire, the bead wires are installed with the same distance between the bead wires, and

[0032] ; during the shaping step, when the radial expansion of the central portion of the carcass ply reaches an intervention diameter strictly less than the constitution diameter, a triangulation member is brought into contact with the carcass ply in order to modify the orientation of the carcass reinforcements during a continuation of the shaping, said triangulation member being provided with parallel reinforcements forming a non-zero angle with the circumferential direction j and the initial direction of the reinforcements of the carcass ply, the diameter

[0033] 15 intervention and / or the triangulation member being different during the manufacture of the first tire and during the manufacture of the second tire.

[0034] The installation of the triangulation member at the intervention diameter allows, without modifying the adjustment of the distance between the rods, to modify the axial length of the sheet

[0035] 10 carcass and therefore to manufacture tires of different dimensions, and in particular makes it possible to use a carcass ply of the same initial axial width, connecting the bead wires, to obtain tires of different dimensions. This results in a simplification of the logistics and the manufacture of tires of different dimensions. The invention is advantageously supplemented by the following various characteristics taken alone or according to their different possible combinations:

[0036] - the intervention diameter is at least 10 mm less than the construction diameter, preferably at least 20 mm less;

[0037] 5 - the triangulation member has an axial width less than 80% of the final width of the tire;

[0038] - the parallel reinforcements of a triangulation member form, before and during contact with the carcass ply, an angle of between 65° and 80° with the carcass reinforcements;

[0039] 1- the triangulation organ is a fabric impregnated with an elastomeric mixture;

[0040] 10 - the triangulation member is brought into contact with the carcass ply on an outer surface of the carcass ply;

[0041] - the manufacture of the first tire uses a first triangulation member provided with parallel reinforcements forming a first non-zero angle with the circumferential direction and the initial direction of the carcass reinforcements, and the manufacture of the second tire uses a

[0042] 15 second triangulation member provided with parallel reinforcements forming a second non-zero angle with the circumferential direction and the initial direction of the reinforcements of the carcass ply, the second angle being different from the first angle by at least 5°;

[0043] - the manufacture of the first tire uses a first triangulation member having; a first axial width, and the manufacture of the second tire uses a second triangulation member having a second axial width, the second axial width being different from the first axial width by at least 10 mm;

[0044] - during the manufacture of the first tire, a triangulation member is brought into contact with the carcass ply of said first tire at a first intervention diameter, and during

[0045] ; of the manufacture of the second tire, a triangulation member is brought into contact with the carcass ply of said second tire at a second intervention diameter, the second intervention diameter being different from the first intervention diameter by at least 10 mm. The invention also relates to a tire comprising, according to a radial arrangement:

[0046] 10 an inner rubber, a carcass ply, a crown ply, a tread, the tire further comprising a triangulation member in contact with the carcass ply, arranged radially under the crown ply, the triangulation member having an axial width less than 80% of the final width of the tire. The tire may have all the characteristics of a tire manufactured according to the method of the invention, and is preferably manufactured according to the method of the invention. The invention may relate to a first tire and a second tire as specified, having different dimensions but comprising the same carcass ply with a different axial length due to the use of the triangulation member.

[0047] 5

[0048] Presentation of figures

[0049] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0050] 10 - Figure 1 shows an example of a partial sectional view of the installation of an annular bead wire at a width end portion of the carcass ply of a tire during its manufacture, according to a possible embodiment of the invention,

[0051] - figure 2 shows an example of a partial sectional view of the carcass ply during a first part of the shaping step, before the triangulation member comes into contact,

[0052] 15 - Figure 3 shows an example of a partial sectional view of the carcass ply when the triangulation member is brought into contact,

[0053] - figure 4 shows a schematic top view of the spatial organization of the respective reinforcements of the carcass ply and the triangulation member, before the second part of the shaping step,

[0054] 10 - Figure 5 shows a schematic top view of the spatial organization of the respective reinforcements of the carcass ply and the triangulation member, during the second part of the shaping step,

[0055] - Figure 6 shows an example of a partial sectional view of the carcass ply during a

[0056] ; second part of the conformation step, after contacting the triangulation member,

[0057] 15 - Figure 7 shows an example of a partial sectional view of a tire during its manufacture, during the installation of at least one crown ply during a constitution step following the shaping step,

[0058] - figure 8 shows an example of a partial sectional view of a tire during its manufacture, after the tread has been fitted,

[0059] 10 - Figure 9 is a graph showing examples of distances between the intervention diameter and the constituent diameter as a function of the reduction in the distance between the beads to obtain a 245 / 45 RI 8 tire, depending on the type of triangulation member used, - Figure 10 is a graph showing examples of distances between the intervention diameter and the constituent diameter as a function of the reduction in the distance between the beads to obtain a 235 / 55 RI 9 tire, depending on the type of triangulation member used

[0060] 5 Detailed description

[0061] The method according to the invention allows the manufacture of a first tire and the manufacture of a second tire, the first tire and the second tire having different dimensions, although during the manufacture of the first tire and the manufacture of the second tire the annular bead wires are put in place with the same initial inter-bead distance. In order to describe the method allowing such a result, with reference to Figures 1, 2, 3, 4, 7 and 8, a tire manufacturing method will be described. It should be noted that for reasons of simplicity, these figures only represent a part of the tire or its components in a meridian plane, due to the symmetry of the tire.

[0062] The tire manufacturing process is a so-called "flat" process in which the process begins with steps of placing elements on a cylindrical drum 1 having a central axis. The cylindrical drum is configured to change diameter during a subsequent shaping step. Before this shaping step, the cylindrical drum 1 10 has an initial diameter.

[0063] To obtain the flat configuration illustrated in Figure 1, an inner rubber layer 2, for example based on butyl rubber, is generally first placed on the cylindrical drum 1. Then, a carcass ply 4 is placed on the cylindrical drum 1 at this initial diameter, typically on the inner rubber 2. The carcass ply 4 comprises carcass reinforcements 6 extending between two axial end portions of the carcass ply 4 surrounding a central portion of the carcass ply 4. The carcass ply 4 is typically a fabric impregnated with an elastomeric mixture. It should be noted that for reasons of simplicity and clarity, only the carcass reinforcements 6 are illustrated in most of the figures. Axial width is understood to mean the distance measured in a straight line along the axis of rotation.

[0064] 10 of the cylindrical drum 1 (axis OY), or of the tire. Axial length, or LA, means the curvilinear length from bead 8 to bead 8 on the tire along the carcass ply 4, in a meridian plane in the axial OY and radial OZ directions. Bead spacing, or ET, means the distance from bead 8 to bead 8 in a straight line in the axial direction OY in a meridian plane (OY, OZ). Thus, the initial axial length is equal to the initial axial width and the bead spacing in a flat process.

[0065] Figure 4 shows how these carcass reinforcements 6 are initially organized. A plurality of parallel carcass reinforcements 6 are regularly distributed around the circumference of the cylindrical drum 1. Typically, the carcass reinforcements 6, when they are put in place, extend axially, that is to say with a direction parallel to the central axis of the cylindrical drum 1 which is intended to correspond to the rotation axis of the tire, perpendicular to a direction tangent to the rolling surface of the tire according to the direction of rotation. The angle α formed by the carcass reinforcements 6 with the circumferential direction 10 is generally between 80° and 100°, and preferably between 85 and 95°, and for example 90° as in the example of Figure 4.

[0066] Preferably, the carcass reinforcements 6 are textile cables, each cable being obtained by twisting a twist T2 of N strands of a textile material in a first given direction (respectively direction S or Z), with N>1, each strand resulting from overtwisting

[0067] 15 of a twist Tl of a yarn of said textile material, in a second direction opposite to the first direction. Preferably, the yarns are made up of a hybrid assembly of filaments of textile materials such as (nylon, PET, aramid). Advantageously, the number N of strands for twisting is between 2 and 6, and preferably N = 2. j Preferably the overtwisting twist Tl, and the twisting twist T2 are identical, and less than 500 turns per meter, preferably Tl, and T2 are identical and less than 440 turns per meter, and even more preferably Tl and T2 are identical and less than or equal to 315 turns per meter. The carcass reinforcements have a strength of between 130 and 340 daN / cm. j Annular rods 8 are then placed at each of the end portions

[0068] 15 axial of the carcass ply 4, the annular bead wires 8 defining between them an inter-bead distance ET. The inter-bead distance ET is the length measured from bead wire 8 to bead wire 8 along the carcass ply 4, in the axial direction Oy. The carcass ply 4 is then a textile or metal reinforcement connecting the two bead wires 8. In detail, and conventionally, a bead is formed by folding the axial end portions of the carcass ply 4,

[0069] 10 thus enclosing each rod 8.

[0070] Following the obtaining of the flat configuration illustrated in Figure 1, a tire shaping step is carried out, during which a radial expansion of the central portion of the carcass ply 4 is caused until said carcass ply 4 reaches a constitution diameter, which is the diameter at which the crown plies are placed. For example, the carcass can be transferred to another cylindrical drum 1, and air can be injected into the carcass in order to inflate it, thus causing a radial expansion of the carcass ply 4. It is also possible to keep the carcass on the same cylindrical drum 1. Other methods can be used in order to cause the radial expansion 5 of the central portion of the carcass ply 4.For reasons of clarity and simplicity, the cylindrical drum 1 is not shown during its radial expansion, this only compressing the carcass ply 4 outwards via the inner rubber 2.

[0071] Within the framework of the invention, this conformation step is divided into two parts: a first part and a second part.

[0072] 10 The first part of the shaping step is similar to the shaping of the methods of the prior art. On the other hand, when the radial expansion of the central portion of the carcass ply 4 reaches an intervention diameter strictly less than the constitution diameter, a triangulation member 10 is brought into contact with the carcass ply 4 in order to modify the orientation of the carcass reinforcements 6 during a continuation of the shaping.

[0073] 15 The triangulation member 10 can be defined as a triangulation ply. Preferably, for reasons of ease of implementation, the radial expansion of the central portion of the carcass ply 4 can be temporarily stopped in order to allow the triangulation member 10 to be brought into contact, but it is possible not to stop the radial expansion of the central portion of the carcass ply 4.

[0074] 10 This triangulation member 10 is provided with parallel triangulation reinforcements 12 forming a non-zero angle with the circumferential direction and the initial direction of the reinforcements 6 of the carcass ply 4, as illustrated in Figure 4. The angle P formed by the triangulation reinforcements and the circumferential direction OX is typically between 10° and 30°, and preferably between 15° and 20°, i.e. an angle with the carcass reinforcements of between 50° and 90°, 15 and preferably between 65° and 80°.

[0075] The triangulation member 10 has, at the time of its installation, an axial width, that is to say in the direction of the bead spacer ET and therefore of the axis of the drum 1 (axis OY), between 30% and 80% of the final width of the tire. More precisely, the axial width of the triangulation member 10 can be between 80 mm and 160 mm, and

[0076] 10 preferably between 100 mm and 150 mm. For example, an axial width of the triangulation member of 100 mm may represent between 30% and 50% of the final width of the tire, while an axial width of the triangulation member 10 of 150 mm may represent between 50% and 80% of the final width of the tire. More generally, the triangulation member 10 preferably has an axial width less than 80% of the final width of the tire. The final width of the tire is understood as the width in the standardized designation of the dimensions of the tire. It is recalled that the axial width of the triangulation member 10 is the straight-line distance along the axial direction OY of the triangulation member 10, in a section of the tire.

[0077] 5 Advantageously, the triangulation member 10 may have characteristics similar to those of the carcass ply 4, in particular in terms of composition or manufacture, except in terms of initial axial width, which is for the triangulation member 10 less than the initial inter-bead distance. For example, the triangulation reinforcements 121 may be manufactured in the same way as the carcass reinforcements 6, although with

[0078] 10 different angular orientations. Typically, the triangulation member 10 is a fabric impregnated with an elastomeric mixture. It is however possible to make certain characteristics of the triangulation member 10 differ from the carcass ply 4, since their functions are quite different.

[0079] Typically, the triangulation member 10 is brought into contact with the carcass ply 4 15 on a radially outer surface of the carcass ply, as illustrated in Figure 3. In other words, the triangulation member 10 is added to the outside of the carcass ply 4.

[0080] The radial expansion of the central portion of the carcass ply 4 is continued during a second part of the shaping step. The contact between the triangulation member 10 j and the carcass ply 4 causes a modification of the orientation of the carcass reinforcements 6 at least

[0081] 10 in the contact zone, as illustrated in Figure 5. More precisely, in the contact zone, the angle a' formed by the carcass reinforcements 6 with the circumferential direction OX is modified in a direction opposite to the initial angle P formed by the triangulation reinforcements 12 and the circumferential direction OX. This angle P formed by the triangulation reinforcements 12 and the circumferential direction OX is also altered to an angle P' during the second part of

[0082] 15 the shaping step. Due to the modification of the orientation of the carcass reinforcements 6, which move away, in the contact zone with the triangulation member 10, from an orientation close to the axial direction (angle a between 80 and 100°, and rather between 85° and 95° relative to the circumferential direction OX), while keeping the same physical extent, this results in a reduction of the axial length of the carcass ply 4. The modification of the angle P results in

[0083] 10 also a reduction in the axial width of the triangulation member 10. Thus, the triangulation member 10, after shaping and in particular in the finished tire, still has a final axial width less than 80% of the final width of the tire. Preferably, the triangulation member 10 has, after shaping and in particular in the finished tire, a final axial width less than 80% of the axial width of each crown ply NST1, NST2. Figure 5 shows schematically how the angular orientations of the carcass reinforcements 6 and the triangulation reinforcements 12 are modified. The deviation undergone by these reinforcements 6, 12 depends essentially on the following parameters:

[0084] - the increase in diameter during the second part of the radial expansion, which depends on the 5 relationship between the intervention diameter and the constitution diameter,

[0085] - 1' respective initial angular orientations of the carcass reinforcements 6 (angle a) and the triangulation reinforcements 12 (angle P),

[0086] - the axial width of the contact zone, and therefore the axial width of the triangulation member

[0087] 110.

[0088] 10 The radial expansion of the central portion of the carcass ply 4 is continued during the second part of the shaping step until the carcass ply 4 reaches a constitution diameter, as illustrated in Figure 6. It is to this constitution diameter that the crown plies and the tread are added.

[0089] 1Since it is during the second part of the conformation stage that the organ acts

[0090] 15 of triangulation 10, it is preferable to obtain a significant effect that this second part includes a non-negligible radial expansion of the carcass ply 4: the more the radial expansion occurs with the triangulation member 10, the more the orientation of the carcass reinforcements 6 can be modified, and the more it is possible to reduce the axial length of the carcass ply 4. Thus, the intervention diameter is preferably at least 10 mm lower than the constitution diameter, and preferably at least 20 mm lower.

[0091] The manufacture of the tire is then continued by a step of constituting the tire comprising the placement, on a radially external face of the carcass ply 4, of at least one crown ply, NST1, NST2 provided with parallel reinforcements j forming a non-zero angle with the circumferential direction OX and the direction of the reinforcements

[0092] 15 carcass 6. The crown plies, NST1, NST2 are arranged so that their respective reinforcements cross each other and with the reinforcements of the carcass ply 4, in order to form by superposition triangular cells, and therefore non-deformable, which guarantee the good road holding of the tire. The installation of the crown plies NST1, NST2 and the characteristics thereof are conventional and known to those skilled in the art, and do not

[0093] 10 will not be described in more detail. However, it should preferably be noted that the diameter of the cylindrical drum 1 no longer increases once the construction diameter is reached, since it is not necessary for the crown plies NST1, NST2 to act on the carcass reinforcements 6. In the example illustrated, the triangulation member 10 is found in the tire after manufacture, between the carcass ply 4 and the first crown ply NST1. Finally, the construction step ends with the installation of a tread at the top of the tire, possibly with the installation of a hoop before the installation of the tread. Advantageously, the installation of at least one crown ply, NST1, NST2 is obtained by keeping said crown ply, 5 NST1, NST2, and the tread in place until the carcass reaches them during its radial expansion.

[0094] Then follow the subsequent stages of tire manufacturing, such as curing or vulcanization. These and subsequent stages of construction being conventional and known to those skilled in the art, they will not be described in further detail.

[0095] 10 Figure 8 shows an example of a tire obtained by the present method, this time with the representation of the elastomer mixture. It should be noted that the triangulation member 10 is present in the final tire, which comprises, in a radial arrangement: an inner rubber 2, a carcass ply 4, a crown ply NST1, NST2, a tread 20, the tire further comprising a triangulation member 10 in contact 15 with the carcass ply, arranged radially under the crown ply NST1, NST2, the triangulation member 10 having a final axial width less than 80% of the final width of the tire.

[0096] As mentioned in relation to Figure 5, several parameters make it possible to obtain; tires having different dimensions from the same initial distance between the bead wires, which in particular makes it possible to use the same carcass ply 4 (same initial axial width) to obtain tires of different dimensions (with different axial lengths of carcass ply 4). In particular, due to the modification of the angular orientations of the carcass reinforcements 6, there is a reduction in the axial length j of the carcass ply 4, which ultimately produces a modification of the width of the

[0097] 15 pneumatic. The same applies to the width of the contact zone, and therefore the axial width of the triangulation member 10. Thus, with the same initial distance between the beads, it is possible to obtain different tire widths.

[0098] Figure 9 shows examples of the difference A between the intervention diameter and the constitution diameter as a function of the reduction in the axial length of the carcass ply.

[0099] 10 4 to obtain a 245 / 45 RI 8 tire, according to different variants of triangulation member 10. Table 1 shows the characteristics of the four variants of the triangulation member 10 for this example:

[0100] [Table 1] with a the angle formed by the carcass reinforcements 6 with the circumferential direction OX, P the angle formed by the triangulation reinforcements 12 and the circumferential direction OX, and A the difference between the intervention diameter and the constitution diameter. The minimum intervention diameter corresponds to the initial diameter on which the carcass ply 4 is placed, which is that of the rim, i.e. 486 mm for an 18-inch rim size (RI 8).

[0101] Figure 9 can be seen as a chart showing the application methods of a triangulation member 10 in order to obtain a 245 / 45 RI 8 tire from different initial inter-bead distances. For example, by using a triangulation member 10 according to variant 3, and by seeking a reduction in the axial length of the carcass ply 4 of the order of 65 mm compared to the initial inter-bead distance, the triangulation member 10 must be brought into contact with the carcass ply at an intervention diameter 60 mm smaller than the constituent diameter.

[0102] Figure 10 shows examples of the difference A between the intervention diameter and the construction diameter as a function of the reduction in the distance between the beads to obtain a 235 / 55 RI 9 tire, according to different variants of the triangulation member. Table 2 shows the characteristics of the four variants of the triangulation member 10:

[0103] [Table 2] with a the angle formed by the carcass reinforcements 6 with the circumferential direction, a the angle formed by the triangulation reinforcements 10 and the circumferential direction, and A the difference between the intervention diameter and the constitution diameter. The minimum intervention diameter corresponds to the initial diameter on which the carcass ply 4 is placed, which is that 5 of the rim, i.e. 510 mm for a 19-inch rim size (R 19).

[0104] Like Figure 9, Figure 10 can be seen as a chart indicating the application methods of a triangulation member 10 in order to obtain a 235 / 55 RI 9 tire from different initial bead distances. For example, by using a triangulation member 10 according to variant 3, and by seeking a reduction in the axial length 10 of the carcass ply 4 of the order of 65 mm compared to the initial bead distance, the triangulation member 10 must be brought into contact with the carcass ply 4 at an intervention diameter 40 mm smaller than the constituent diameter.

[0105] These examples show that it is possible, by using the triangulation member 10,1, to obtain very different tire dimensions from the same distance between-

[0106] 15 initial bead wire. It is easy to obtain reductions in the axial (curvilinear) length of the carcass ply 4 up to 70 mm, or even more depending on the characteristics of the tires and the triangulation member 10. It is thus possible to continue to use the same carcass ply 4, with the same initial axial width corresponding to the distance between the bead wires, because the process makes it possible to obtain different axial lengths for the carcass ply 10 4 at the end of shaping.

[0107] Thus, after having manufactured a series of first tires having first dimensions, and in particular a first curvilinear axial length of carcass ply 4, it is possible, without modifying the initial distance between the bead wires, to manufacture a series of second tires having second dimensions different from the first dimensions, and

[0108] 15 in particular a second curvilinear axial length of carcass ply 4 different from the first curvilinear axial length of carcass ply 4 in the final tire. It is sufficient to vary the intervention diameter and / or the triangulation member 10 between the manufacture of the first tires and the manufacture of the second tires. It is then possible to use the same carcass ply 4, with the same axial width, for the first

[0109] 10 tires and the second tires. In fact, the initial axial width of the carcass ply 4 is dictated by the distance between the beads ET, and this remains the same.

[0110] Thus, by using identical or different triangulation members 10, but with different intervention diameters, the second part of the shaping will have a different duration, and different effects on the carcass ply 4. For example, during the manufacture of the first tire, a triangulation member 10 is brought into contact with the carcass ply of said first tire at a first intervention diameter, and during the manufacture of the second tire, a triangulation member 10 (identical or different from that used for the first tire) is brought into contact with the carcass ply 4 of said second tire at a second intervention diameter, the second intervention diameter being different from the first intervention diameter. Preferably, the second intervention diameter differs by at least 10 mm from the first intervention diameter.

[0111] The two triangulation members 10 may be different, and may in particular be distinguished by the angle P formed by the triangulation reinforcements 12 with the circumferential direction 10. In particular, when the manufacture of the first tire uses a first triangulation member 10 provided with parallel reinforcements 12 forming a first non-zero angle with the circumferential direction and the initial direction of the carcass reinforcements 6, and when the manufacture of the second tire uses a second triangulation member 10 provided with parallel reinforcements 12 forming a second non-zero angle with the circumferential direction 15 and the initial direction of the carcass reinforcements 6, the second angle is preferably different from the first angle by at least 5°.

[0112] Two triangulation members 10 may also be distinguished by their respective axial widths. For example, the manufacture of the first tire may use a first triangulation member 10 having a first axial width, and the manufacture of the second tire may use a second triangulation member 10 having a second axial width, the second axial width being different from the first axial width by at least 10 mm (greater or smaller).

[0113] As a result, it is possible to obtain a first tire and a second tire j as specified, having different dimensions but comprising the same ply

[0114] 15 carcass 4 (same initial axial width corresponding to the same distance between the beads ET) with a different axial length between the two tires due to the use of the triangulation member 10.

[0115] By using all these possibilities, it is possible to manufacture a whole range of tires from the same distance between beads, and therefore without changing many

[0116] 10 adjustments of the cylindrical drum 1 or even without changing certain parts, such as the carcass ply 4 which can remain the same. In addition, this results in a very great logistical simplification since it is no longer necessary to provide a different supply and storage for each tire size. The invention is not limited to the embodiment described and shown in the appended figures. Modifications remain possible, in particular from the point of view of the constitution of the various technical characteristics or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims

Claims 1. A method of manufacturing tires comprising manufacturing a first tire and manufacturing a second tire, the first tire and the second tire 5 having different dimensions, the manufacture of the first tire and the manufacture of the second tire comprising the following steps: - placing a carcass ply (4) on a cylindrical drum (1) at an initial diameter, said carcass ply comprising carcass reinforcements (6) extending between two axial end portions of the carcass ply (4) surrounding a central portion of the carcass ply, 10 - installation of rods (8) at each of the axial end portions of the carcass ply (4), the rods (8) defining between them an inter-rod distance (ET), - a step of shaping the tire by causing radial expansion of the central portion of the carcass ply (4) until said carcass ply reaches a constitution diameter, 15 - a step of constituting the tire comprising the placement, on a radially external face of the carcass ply, of at least one crown ply (NST1, NST2) provided with parallel reinforcements forming a non-zero angle with the circumferential direction and the direction of the reinforcements of the carcass ply (6), and the placement of a tread, characterized in that during the manufacture of the first tire and the manufacture of the second tire, the bead wires (8) are placed with the same distance between the bead wires, and in that during the shaping step, when the radial expansion of the central portion of the carcass ply (4) reaches an intervention diameter strictly less than the diameter of; constitution, a triangulation member (10) is placed in contact with the carcass ply (4) in order 15 to modify the orientation of the carcass reinforcements (6) during a continuation of the shaping, said triangulation member (10) being provided with parallel reinforcements (12) forming a non-zero angle (P) with the circumferential direction and the initial direction of the reinforcements of the carcass ply, the intervention diameter and / or the triangulation member being different during the manufacture of the first tire and during the manufacture of the second tire. 10 2. Method according to claim 1, in which the intervention diameter is at least 10 mm less than the constitution diameter, preferably at least 20 mm less.

3. Method according to any one of the preceding claims, in which the triangulation member (10) has an axial width less than 80% of the final width of the tire. 5 4. Method according to any one of the preceding claims, in which the parallel reinforcements of a triangulation member form, beforehand and during contact with the carcass ply, an angle of between 65° and 80° with the carcass reinforcements.

15. A method according to any preceding claim, wherein the organ of 10 triangulation is a fabric impregnated with an elastomeric mixture.

6. A method according to any preceding claim, wherein the triangulation member is brought into contact with the carcass ply on an outer surface of the ply. 1 carcass. 15 7. Method according to any one of the preceding claims, in which the manufacture of the first tire uses a first triangulation member (10) provided with parallel reinforcements (12) forming a first non-zero angle with the circumferential direction and the initial direction j of the carcass reinforcements (6), and the manufacture of the second tire uses a second 10 triangulation member provided with parallel reinforcements forming a second non-zero angle with the circumferential direction and the initial direction of the reinforcements of the carcass ply, the second angle being different from the first angle by at least 5°. ; 8. A method according to any preceding claim, wherein the manufacture of the 15 first tire uses a first triangulation member (10) having a first axial width, and the manufacture of the second tire uses a second triangulation member (10) having a second axial width, the second axial width being different from the first axial width by at least 10 mm. 10 9. Method according to any one of the preceding claims, in which during the manufacture of the first tire, a triangulation member is brought into contact with the carcass ply of said first tire at a first intervention diameter, and during the manufacture of the second tire, a triangulation member is brought into contact with the carcass ply of said second tire at a second intervention diameter, the second intervention diameter being different from the first intervention diameter by at least 10 mm.

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