Method and apparatus for building tyres

Abstract

A forming drum (14) is arranged, comprising radially movable circumferential successive sectors (16), each comprising a central body (18) and a pair of interchangeable inserts (23), each of which engages an axial end edge (19) of the central body (18). The forming drum (14) is brought into an expanded condition, in which the sectors (16) are radially moved away from said geometric axis (X-X), in order to define a radially outer laying surface (S) on which the components of a first tyre (2) being processed are applied. During expansion of the forming drum (14), the inserts (23) of each sector (16) are moved with respect to the respective central body (18) until an operating position in which said inserts (23) each extend on a continuous portion belonging to the inserts (23) of circumferentially adjacent sectors (16), in order to form a substantially continuous annular element (31) extending along the axially opposite edges (20) of the forming drum (14).

Description

Technical Field

[0001] The present invention relates to a method and apparatus for constructing tires for vehicle wheels.

[0002] More specifically, the present invention is intended for use in constructing raw tires, which are then subjected to vulcanization cycles to obtain a final product. Background Technology

[0003] Tires for vehicle wheels typically include a carcass structure comprising at least one carcass ply having correspondingly opposing ends that engage with a corresponding annular anchoring structure integrated in an area typically identified by the name "bead," the inner diameter of which substantially corresponds to the tire's so-called "fitting diameter" on the corresponding mounting rim.

[0004] The carcass structure is associated with the crown structure, which may include one or more belt layers radially stacked relative to each other and relative to the carcass plies, having fabric or metal reinforcing cords having a cross orientation and / or substantially parallel to the tire's circumferential extension direction (0 degrees). A tread band is applied at a radially outer position relative to the belt layers, the tread band also being made of an elastomeric material, like the other semi-finished products constituting the tire.

[0005] A corresponding sidewall made of an elastomeric material is applied to an axially external position on the lateral surface of the tire carcass structure, with each sidewall extending from one of the lateral edges of the tread strip to a corresponding annular anchoring structure of the bead. In tubeless tires, an impermeable covering layer, commonly referred to as a "liner," covers the inner surface of the tire.

[0006] After the construction of the raw tire is achieved by assembling the corresponding components, molding and vulcanization processes are typically performed. The purpose of these processes is to determine the structural stability of the tire by crosslinking the elastomer composition, as well as to impart the desired tread design and possible unique geometric markings on the tire sidewalls if necessary.

[0007] The term "elastomer material" refers to a composition comprising at least one elastomeric polymer and at least one reinforcing filler. Preferably, such a composition also includes additives, such as, for example, crosslinking agents and / or plasticizers. Due to the presence of the crosslinking agent, this material can be crosslinked by heating, thereby forming the final finished product.

[0008] "Tires for two-wheeled vehicles," especially motorcycle tires, refers to tires with a curvature ratio roughly between 0.15 and 0.45.

[0009] The “curvature ratio” of a tire (or a portion thereof) refers to the ratio between the distance measured on the radial plane of the tire (or said portion thereof) from the radially outer point of the tread strip (or outer surface) to the line passing through the laterally opposite ends of the tread itself (or outer surface itself), and the distance between said ends measured along the chord of the tire (or a portion thereof).

[0010] The “curvature ratio” of a forming drum refers to the ratio between the distance measured on the radial plane of the forming drum from the radially outer point of the outer surface of the forming drum to the line passing through the lateral opposite ends of the forming drum itself, and the distance measured along the chord of the forming drum between the ends.

[0011] The terms "radial" and "axial" are used in conjunction with the radial direction of the forming drum / tire (i.e., the direction perpendicular to the axis of rotation of the forming drum / tire) and the axial direction of the forming support / tire (i.e., the direction parallel to the axis of rotation of the forming drum / tire), and the expressions "radial inside / outer" and "axial inside / outer" are used. Alternatively, the terms "circumferential" and "circumferentially" are used with reference to the annular extension of the forming support / tire.

[0012] When it contains the axis of rotation of the forming drum or the tire respectively, the plane about the forming drum or the tire is defined as "radial".

[0013] "Primary semi-finished product" refers to a continuous elongated element made of an elastomeric material. Preferably, such a continuous elongated element may comprise one or more fabric and / or metal and / or hybrid cords. Preferably, such a continuous elongated element may be cut to a specified size.

[0014] A tire's "component" or "structural component" means any part of the tire that performs its own function or a portion thereof. Tire components include, for example, the liner, the underlayer liner, the sidewall insert, the bead core, the filler insert, the wear element, the sidewall, one or more carcass plies, one or more belt plies, the tread belt, the underlayer of the tread belt, the underlayer belt insert, etc., or a portion thereof.

[0015] The tire body structure and tire crown structure, typically in the form of sleeves, are usually manufactured separately at the respective workstations for subsequent assembly.

[0016] Document WO 2015 / 097636A1, under the same applicant's name, describes an annular forming drum that expands within a formed carcass sleeve to support the carcass sleeve against an abutment surface present on the outer side of the forming drum. A primary semi-finished product is applied around the formed carcass sleeve, pressing the primary semi-finished product against the abutment surface. The abutment surface has circumferential rows of solid portions alternating with void portions. The solid portions arranged along the axially opposite circumferential edges of the abutment surface have a lateral dimension between 10% and 60% of the lateral dimension presented by the solid portions arranged near the axial centerline plane of the abutment surface.

[0017] Document WO 2016 / 157001A1, under the same applicant's name, describes a forming drum comprising successive segments radially movable between a contracted state and an expanded state, in which the segments radially move away from a geometric axis to define a radially outward abutment surface. Each segment has circumferentially opposing connecting portions, each connecting portion including circumferential protrusions alternating with circumferential cavities. The protrusions of each segment slidably engage in a corresponding cavity of a circumferentially adjacent segment. At least one support wing extends from at least one of the protrusions, the support wing having a first side and a second side respectively opposite to each other. The first side coincides with a portion of the abutment surface, and the second side at least partially extends beyond one of the protrusions belonging to an adjacent segment.

[0018] According to the applicant, the above-described production system of the type shown in documents WO 2015 / 097636A1 and WO 2016 / 157001A1 allows for improved product quality, wherein the tire crown structure is directly manufactured on the tire carcass structure while the tire carcass structure is supported by a forming drum, the forming drum being used to obtain the tire carcass structure or can be externally coupled to a previously formed tire carcass structure. Summary of the Invention

[0019] Nevertheless, the applicant has observed that the aforementioned forming drum is not well-suited to withstand relatively high mechanical stresses. For example, in production processes where the carcass structure is manufactured directly on the forming drum, the application of the annular anchoring structure and / or other components involves the transmission of relatively high axial thrust against the axially opposite edges of the forming drum. The presence of surface discontinuities in these areas often determines the occurrence of high local pressures, resulting in a risk of premature wear and / or breakage.

[0020] The applicant has also observed that if production requirements necessitate frequent changes to the geometry and structural characteristics of the produced tires, it is necessary to arrange and manage a large number of forming drums, each adapted to the specific tire size to be obtained. This involves logistical difficulties in managing the necessary storage space to accommodate the forming drums, as well as costs arising from the high investment required to manufacture individual forming drums.

[0021] The applicant has realized that by creating a substantially continuous abutment surface on a more axially outer portion of the forming drum through corresponding auxiliary elements that removably engage with the sector, the application of the tire components being processed can be simplified while simultaneously achieving simple geometric and dimensional adaptability of the forming drum itself.

[0022] More specifically, the applicant has ultimately discovered that by arranging axially opposed auxiliary elements or inserts near the axially opposed edges of each segment of the forming drum, elements having a substantially continuous annular surface extending along the axially opposed edges of the forming drum can be formed, thereby simplifying the laying of the tire components being processed on the forming drum itself and increasing the structural strength of the forming drum relative to the stresses induced during processing. The geometry and dimensional characteristics of the inserts can also be advantageously selected as needed to limit or eliminate the risk of undesirable air pockets forming between the various components laid on the forming drum.

[0023] According to one aspect, the present invention relates to a method for constructing a tire.

[0024] Preferably, an expandable annular forming drum is provided, the forming drum comprising radially movable successive sectors.

[0025] Preferably, each sector includes a central body and a pair of interchangeable inserts, each of which is removably engaged at the corresponding axial end edge of the central body.

[0026] Preferably, the forming drum expands from a contracted state to an expanded state, in which the sector moves close to the geometric axis of rotation of the forming drum, and in the expanded state the sector moves radially away from the geometric axis to define a radially outward laying surface extending between two axially opposite edges of the forming drum.

[0027] Preferably, at least one component of the first tire being treated is applied to the laying surface of the forming drum.

[0028] Preferably, during the expansion of the forming drum, the insert of each sector moves relative to the corresponding central body until an operating position is reached, in which each of the inserts extends over a continuous portion of the inserts belonging to the circumferentially adjacent sector.

[0029] Preferably, in the operating position, the insert forms an annular element extending along the axial opposite edges of the forming drum.

[0030] According to another aspect, the present invention relates to an apparatus for constructing tires for vehicle wheels.

[0031] Preferably, the device includes an expandable annular forming drum having a radially outward laying surface extending between two axially opposite edges of the forming drum.

[0032] Preferably, the device includes an application means for applying components of the tire being processed onto the laying surface of the forming drum.

[0033] Preferably, the forming drum includes successive segments that are radially movable between a contracted state and an expanded state, wherein in the contracted state the segments move closer to the geometric axis of rotation of the forming drum, and in the expanded state the segments move radially away from the geometric axis, in order to define the laying surface.

[0034] Preferably, each sector includes a central body and a pair of interchangeable inserts, each of which is removably engaged at the corresponding axial end edge of the central body.

[0035] Preferably, the inserts can move simultaneously with the expansion of the forming drum from a contracted state to an expanded state until an operating position is reached, in which each of the inserts extends over a continuous portion of the inserts belonging to circumferentially adjacent sectors to form an annular element extending along the axially opposite edges of the forming drum.

[0036] The applicant believes that the presence of annular elements, i.e., elements having annular surfaces with substantially continuous extensions, can facilitate the application of structural components to the proximal sides of the axially opposite edges of the forming drum. In particular, annular elements defined by inserts in the operating position are adapted to effectively withstand stress, even considerable stress, thereby maintaining the structural integrity of the forming drum during the application of high axial thrust required for the application of specific components, such as, for example, annular reinforcement structures. Furthermore, the applicant believes that if each of the annular elements consists of multiple inserts, each oscillatingly constrained to one of the sectors, the potential for contraction and expansion of the forming drum is not affected. The presence of annular elements formed by movable inserts also allows the forming drum to be easily adapted to handle tires with different structures and / or geometries. In fact, the inserts are adaptable to be easily replaced with inserts of different sizes or geometries to modify the shape of the forming drum according to production requirements. Manufacturing inserts for obtaining annular elements of different shapes and sizes is much less time and costly than manufacturing the entire forming drum, and also significantly reduces the storage space required for disassembling the inserts.

[0037] In at least one aspect of the foregoing, the invention includes one or more of the following preferred features described below.

[0038] Preferably, the inserts form a first series of inserts, wherein after the treated first tire is removed, the first series of inserts are removed from the sector of the forming drum and the first series of inserts are replaced with inserts belonging to the second series and having a different size than the first series of inserts before at least one component of the treated second tire is applied to the laying surface of the forming drum.

[0039] The availability of different insert series allows for easy adjustment of the geometry and dimensional characteristics of the forming drum according to production requirements, thus also contributing to production flexibility in different tire batches.

[0040] Preferably, the inserts are brought from a rest position to an operating position, in which each insert extends transversely in a circumferential direction concentric with respect to the geometric axis of the forming drum.

[0041] The orientation of the inserts in a direction transverse to the circumferential direction allows the forming drum to shrink in diameter without mechanical interference or blockage between successive circumferential inserts.

[0042] Preferably, in the operating position, each insert arranged along the axial opposite edge of the forming drum extends in a circumferential direction concentric with respect to the geometric axis of the forming drum, in a manner that one continues on the other.

[0043] This contributes to the surface continuity of the annular element formed by the insert in the operating position.

[0044] Preferably, in the operating position, the corresponding circumferential relative end wall of each insert mates with one of the end walls of the circumferentially adjacent inserts.

[0045] Preferably, each insert rotates about a rotation axis that extends axially through the placement plane of the corresponding axial end edge of the central body.

[0046] According to the applicant, the rotatable connection represents the best solution, with a simple structure and reliable function, to facilitate the movement of the insert between the rest position and the operating position.

[0047] Preferably, each insert is elastically pushed into the operating position.

[0048] The structure of the forming drum is thus simplified, eliminating the need for levers or other drive systems to move the insert toward the operating position.

[0049] Preferably, during the shrinkage of the forming drum, each insert is pushed to a resting position by a protrusion belonging to the adjacent sector, the protrusion acting on a cam portion carried by the insert itself.

[0050] Preferably, the at least one component is applied by an axial thrust acting against the axially opposite edge of the forming drum.

[0051] Preferably, each insert has an axial inner wall that acts axially on the central body in an abutment relationship to resist the axial thrust transmitted to the forming drum during the application of the insert.

[0052] Preferably, the process also includes radially shrinking the forming drum after the application of the at least one component and removing the treated first tire from the forming drum.

[0053] Preferably, the radially outer paved surface is substantially continuous.

[0054] Preferably, each sector has a central body that carries the circumferentially opposite connecting portions.

[0055] Preferably, each of the connecting portions includes a circumferential protrusion that alternates with the circumferential cavity.

[0056] Preferably, the protrusion of each sector segment is slidably engaged in the corresponding cavity of the circumferentially adjacent sector segment.

[0057] Preferably, the central body of each sector is axially defined between two opposite axial end edges.

[0058] Preferably, the axial end edges are spaced apart from each other to a degree less than the total axial dimension of the paved surface.

[0059] Preferably, each of the axial end edges is spaced apart from one of the axially opposite edges of the forming drum.

[0060] Preferably, multiple series of inserts with different sizes are provided, each series of inserts being individually and selectively engaged with the central body of the sector to impart a predetermined geometry to the shaped drum.

[0061] Preferably, the annular element defines the axial outer portion of the laid surface.

[0062] The application of semi-finished products and / or components is thus simplified because the annular element can eliminate or significantly reduce surface discontinuities that are often caused by alternations of protrusions and cavities, especially in the axially outer region of the forming drum, where such alternations often hinder the proper application of semi-finished products.

[0063] Preferably, the inserts can be moved from a rest position toward an operating position, in which each insert extends transversely in a circumferential direction concentric with respect to the geometric axis of the forming drum.

[0064] Preferably, each insert has an elongated curved shape in the basic circumferential direction.

[0065] Preferably, in the operating position, each insert extends along a circumferential direction concentric with the geometric axis.

[0066] Preferably, in the operating position, each insert arranged along the axial opposite edge of the forming drum extends in a circumferential direction concentric with respect to the geometric axis of the forming drum, in a manner that one continues on the other.

[0067] Preferably, each insert is rotatably engaged with the central body by a pin extending axially through the corresponding axial end edge of the central body.

[0068] Preferably, each insert is removably connected to the pin by a retaining screw that engages coaxially with the pin itself.

[0069] Therefore, each of the inserts is suitable for easy replacement by simply removing the retaining screw.

[0070] Preferably, each insert is elastically pushed to the operating position by at least one spring operating between the central body of the corresponding sector and the insert itself.

[0071] Preferably, one end of the spring is constrained to an arm that protrudes radially from the pin.

[0072] Therefore, the return spring and pin can remain constrained to the corresponding sector during the removal of the insert, thus simplifying its replacement without requiring the removal and reinstallation of the pin and spring.

[0073] Preferably, the arm is located radially inside one of the connecting portions, next to one of the protrusions.

[0074] Preferably, each insert has an axial inner wall pointing toward the central body of the corresponding sector.

[0075] Preferably, the axial inner wall is substantially flat.

[0076] Preferably, the axial inner wall acts in an abutting relationship on the abutting surface supported by the central body of the corresponding sector at the corresponding axial end edge.

[0077] Preferably, the contact surface is substantially flat.

[0078] Preferably, the axial inner wall of the insert and the abutment surface are slidably fitted in a plane orthogonal to the geometric axis of the forming drum.

[0079] This results in a wide contact surface between the insert and the sector, thereby increasing the structural strength of the component, even in relation to stresses induced during processing, such as when the annular anchor structure approaches the forming drum and / or when one or more ply layers are flipped up to construct the body structure.

[0080] Preferably, each insert has a curved longitudinal extension between at least two circumferentially opposed terminal walls.

[0081] Preferably, in the operating position, the terminal wall of each insert is close to one of the terminal walls of the circumferentially adjacent inserts.

[0082] Preferably, in the operating position, the terminal wall of each insert mates with one of the terminal walls of the circumferentially adjacent inserts.

[0083] Preferably, at least in the operating position, the terminal wall of each insert is parallel to one of the terminal walls of the circumferentially adjacent inserts.

[0084] Preferably, the terminal wall is arranged according to an extension that is inclined relative to the radial direction at the geometric axis of the forming drum.

[0085] Preferably, in the operating position, the terminal wall forms an angle approximately between 15° and 60° with respect to the radial direction at the geometric axis of the forming drum.

[0086] Preferably, in the operating position, the terminal wall forms an angle approximately between 15° and 30° with respect to the radial direction at the geometric axis of the forming drum.

[0087] Preferably, each insert has a cam portion formed into a lateral protrusion shape, the cam portion being arranged on one of the proximal sides of the circumferential relative terminal wall of the insert itself.

[0088] Preferably, each insert has a cam portion having a shape that is complementary to the space between axially outward protrusions belonging to two circumferentially adjacent sectors.

[0089] This gives the laying surface of the shaped drum greater continuity, especially in the region near the axial end edge of the central body.

[0090] Preferably, each insert has a cam portion configured to interact with a central body of one of the circumferentially adjacent sector segments.

[0091] Therefore, without the need for levers and / or other additional drive systems, synchronous movement of the insert toward the resting position is achieved after the forming drum retracts.

[0092] Preferably, the cam portion is shaped as a lateral protrusion so as to interact with one of the protrusions carried by a sector circumferentially adjacent to the sector carrying the insert itself, the cam portion being arranged proximal to one of the circumferentially relative terminal walls of the insert.

[0093] Preferably, at least in the operating position, the cam portion of each insert is close to the radially inner surface of one of the axially outward protrusions of the central body of the sector adjacent to the sector carrying the insert itself.

[0094] As the forming drum begins to contract from its expanded state, the protrusion on the cam portion of the insert helps it resist the action of the spring and rotate around the corresponding pin.

[0095] Therefore, due to the contraction and expansion of the forming drum, the synchronous movement of the insert is effectively driven without the need for levers and / or other additional drive systems. Attached Figure Description

[0096] Further features and advantages will become more apparent from the detailed description of preferred, but not exclusive, embodiments of the method and apparatus for constructing tires for vehicle wheels according to the present invention.

[0097] The description will be illustrated below with reference to the accompanying drawings, which are provided by way of non-limiting example only, in which:

[0098] Figure 1 A schematic top view of the equipment used to construct a tire is shown;

[0099] Figure 2 A truncated perspective view of a forming drum in a radially contracted state according to the present invention is shown;

[0100] Figure 3 It shows a radially expanding state. Figure 2 A truncated perspective view of the formed drum;

[0101] Figure 4 The front view is shown with a truncated section. Figure 3 The forming drum;

[0102] Figure 5 It shows Figure 2 A truncated perspective view with magnified details, showing two circumferentially adjacent sectors;

[0103] Figure 6 It shows Figure 3 A magnified perspective view showing two circumferentially adjacent sectors;

[0104] Figure 7 Shown from different angles and partially truncated perspective views Figure 6One of the fan-shaped sections of the formed drum;

[0105] Figure 8 It is shown in truncated radial section Figure 3 The forming drum;

[0106] Figure 9 The truncated radial section shows a forming drum equipped with inserts belonging to the second series, the geometry of which is... Figures 2 to 7 The first series of inserts depicted in the text are different;

[0107] Figure 10 The radial half-section of a tire, obtainable according to the present invention, is shown schematically. Detailed Implementation

[0108] Referring to the above figures, reference numeral 1 generally indicates a device for constructing a tire for a vehicle wheel. Device 1 is arranged to actuate the construction method according to the invention.

[0109] Device 1 is set up to obtain tire 2 ( Figure 10 The tire essentially comprises at least one carcass ply 3, which is preferably internally covered by an impermeable layer of elastomeric material or a so-called liner 4. Two annular anchoring structures 5 engage with corresponding end flaps 3a of one or more carcass ply 3, each of the annular anchoring structures comprising a so-called bead core 5a, which preferably carries an elastomeric filler 5b in a radially outward position. The annular anchoring structures 5 are integrated proximal to an area generally identified by the name "bead" 6, at which engagement between the tire 2 and the corresponding mounting rim (not depicted) typically occurs.

[0110] A belt structure 7 is circumferentially applied around one or more carcass plies 3, and a tread belt 8 is circumferentially stacked on the belt structure 7. Two sidewalls 9 are applied in laterally opposite positions to one or more carcass plies 3, each sidewall extending from the corresponding bead 6 to the corresponding lateral edge of the tread belt 8.

[0111] The apparatus 1 includes a carcass construction line 10 having one or more construction stations 11, in which the manufacture of a carcass sleeve 12 having a generally cylindrical shape is performed, for example, in a known manner. The carcass construction line 10 leads to a forming station 13, in which the carcass sleeve 12 is formed according to a ring-shaped construction, as described, for example, in the aforementioned document WO 2016 / 157001A1.

[0112] The carcass sleeve 12 includes at least one carcass ply 3, which is preferably covered internally by a liner 4. If desired, the carcass sleeve 12 may also include a sidewall 9 or a first portion thereof, each sidewall or the first portion thereof extending from a corresponding bead 6.

[0113] In the forming station 13, a removable and expandable annular forming drum 14 is preferably engaged.

[0114] The application device 15 operates near the forming station 13 to apply the previously obtained carcass sleeve 12 and / or other components of the tire 2 being processed onto the paving surface S present outside the forming drum 14. For example, the same carcass sleeve 12 can be manufactured directly on the forming drum 14 by applying its individual components (lining, one or more carcass plies, bead core, etc.) onto the paving surface S.

[0115] The connection between the annular anchoring structure 5 and the carcass structure 3 can be performed at the carcass construction line 10, as specified, for example, in document WO2016 / 157001A1. In a possible variant of the embodiment, after the carcass sleeve 12, which lacks an annular anchoring structure, has been arranged on the forming drum 14, the connection between the annular anchoring structure 5 and the carcass structure 3 can be performed at the forming station 13.

[0116] The forming drum 14 can be removably engaged with the same forming station 13 by means of at least one robotic arm 34, which is also adapted to transfer it to a possible additional workstation 33.

[0117] The forming drum 14 can be in a radially contracted state ( Figure 2 and Figure 5 ) and radial expansion state ( Figure 3 , Figure 4 , Figure 6 , Figure 7 , Figure 8 and Figure 9 Expansion between ) . For this purpose, the forming drum 14 includes a central axis 17 (coaxial with the geometric rotation axis XX of the forming drum itself) Figure 1 ) Multiple sectors distributed circumferentially 16.

[0118] Segment 16 can, under the action of a radial motion device, preferably simultaneously with each other, move from the aforementioned contracted state to the expanded state, in which the segment radially approaches the central axis 17, and in the expanded state, the segment 16 radially moves away from the central axis 17, i.e., away from the geometric axis XX. The radial motion devices are not shown in detail because they can be obtained in any known manner, such as those indicated, for example, in WO 2016-157001 or WO 2014-083477.

[0119] In the expanded state, the assemblies of the sector 16 of the forming drum 14 extend circumferentially to define the lay surface S. The lay surface S is annular according to its internal configuration, which at least one portion of the tire carcass sleeve 12 must have after forming is completed. More specifically, the lay surface S of the forming drum 14 in the expanded state may preferably be specified to have a curvature ratio between about 0.15 and about 0.45, a curvature ratio generally suitable for manufacturing tires for motorcycles or other two-wheeled vehicles. However, if desired, a curvature ratio lower than the aforementioned value may be used, for example, for the production of automobile or truck tires.

[0120] like Figures 4 to 7 More preferably, each of the sector segments 16 has a central body 18 axially defined between two opposing axial end edges 19, the two opposing axial end edges being spaced apart by a degree W1 less than the total axial dimension W2 of the laying surface S. Preferably, each axial end edge 19 of the central body 18 is spaced apart from one of the opposing axial edges 20 of the forming drum 14.

[0121] The central body 18 of each segment 16 carries a first connecting portion 18a and a second connecting portion 18b, which are circumferentially opposite each other and preferably interconnected by an intermediate portion 18c, which has a main extending direction parallel to the radial plane of the forming drum 14 at least on the laying surface S. Each of the connecting portions 18a and 18b has a plurality of elongated protrusions 21 extending circumferentially from the intermediate portion 18c, which alternate with corresponding circumferential elongated cavities 22.

[0122] In the same sector 16, the protrusion 21 belonging to one of the connecting parts (e.g., the first connecting part 18a) is offset relative to the protrusion 21 of the other connecting part 18b.

[0123] A more axially outer protrusion 21 of one of the connecting portions (e.g., the first connecting portion 18a) defines an axial end edge 19 of the central body 18 of the corresponding sector 16. The protrusion 21 of each sector 16 is slidably engaged in a corresponding cavity 22 of a circumferentially adjacent sector 16 and is adapted to slide within the cavity itself to support the expansion and contraction movements of the forming drum 14.

[0124] In the contracted state, the protrusion 21 of each sector 16 penetrates into the corresponding cavity 22 until it touches or almost touches the middle portion 18c of the adjacent sector 16. Figure 2 and Figure 5 More specifically, in the contracted state, the protrusions 21 are inserted into the corresponding cavities 22 to a degree equal to at least 80% of their length.

[0125] In the expanded state, the protrusions 21 are drawn out of the cavity 22 to a degree equal to at least 80% of their length, such as... Figure 3 , Figure 4 and Figure 6 Better visibility.

[0126] A pair of interchangeable inserts 23 are associated with the central body 18 of each sector 16, each insert being removably engaged at one of the axial end edges 19 of the central body 18 itself.

[0127] Each insert 23 has an axial inner wall 24 pointing toward the central body 18 of the corresponding sector 16. The axial inner wall 24, preferably flat, acts in an axial abutment relationship on an abutment surface 24a, which is also preferably flat and supported by the central body 18 of the corresponding sector 16 at the corresponding axial end edge 19. The axial inner wall 24 and the abutment surface 24a of the insert 23 are slidably engaged in a plane orthogonal to the geometric axis XX of the forming drum 14.

[0128] Each insert 23 preferably extends longitudinally according to a bend between at least two circumferentially opposed end walls 25. More particularly, the insert 23 has an elongated curved shape in the substantially circumferential direction. The insert 23 can be rotatably engaged with the central body 18 by means of a pin 26 about a corresponding axis of rotation YY, said axis of rotation being arranged perpendicular to the axial inner wall 24 and extending axially through the placement plane containing the corresponding axial end edge 19 of the central body itself. Preferably, as Figure 7 As can be seen more clearly, pin 26 rotatably engages one of the axially outer protrusions 21 of the first connecting portion 18a, which defines the axial end edge 19 of the corresponding central body 18. A retaining screw 27 can engage through insert 23 and is coaxially screwed into pin 26 to secure the pin to insert 23 itself against the axial inner wall 24 of insert 23 pointing towards the central body 18.

[0129] Preferably, each insert 23 is operably coupled to at least one spring 28, such as a helical traction spring, which operates between the insert itself and the central body 18 of the corresponding sector 16. The spring 28 has a first end constrained to the central body 18 and a second end operating on an arm 29 that projects radially from the pin 26 of the corresponding insert 23. More specifically, the arm 29 is preferably located radially inward relative to the central body 18, more precisely at the first connecting portion 18a, next to one of the protrusions in the axially outer protrusion 21, on the side of that protrusion opposite the axial end edge 19 of the central body 18. In the illustrated example, the arm 29 carries a terminal screw 30 projecting from a continuous portion of the arm 29 itself to engage the second end of the spring 28.

[0130] Each insert 23 is preferably movable with the corresponding pin 26 about the axis of rotation YY between a rest position and an operating position, in which the insert is transverse to the circumferential direction CC (concentric with respect to the geometric axis XX of the forming drum 14). Figure 2 The insert extends in the operating position along a circumferential direction CC. Figure 3 ).

[0131] The operating position of the insert 23 corresponds to the expanded state of the forming drum 14. For example, from... Figure 3 and Figure 4 As can be seen, in this configuration, each insert 23 constrained to the corresponding opposing axial end edges 19 of each sector 16 extends along the continuity of the insert 23 belonging to the circumferentially adjacent sector 16. Each insert 23 arranged along the axial opposing edges 20 of the forming drum 14 extends along a circumferential direction CC concentric with respect to the geometric axis XX, such that one insert extends along the continuity of another insert. More specifically, each insert 23 may have a corresponding terminal wall 25, each terminal wall being close to, preferably mating with, and parallel to, one of the terminal walls 25 of the circumferentially adjacent insert 23, which facilitates surface continuity of the assembly.

[0132] Each of the terminal walls 25 of each insert 23 may be arranged to extend in a direction inclined relative to the geometric axis XX of the forming drum 14 and in the radial direction incident with the terminal wall itself. Preferably, in the operating position, each of the terminal walls 25 forms an angle approximately between 15° and 60° with respect to the radial direction R incident with the terminal wall itself at the geometric axis XX, more preferably between 15° and 30°.

[0133] In the operating position, the components of insert 23 form two substantially continuous annular elements 31, each extending along one of the axially opposite edges 20 of the forming drum 14. These annular elements 31 define an axially outer portion of the paving surface S, positioned to provide abutment to the carcass sleeve 12 of the tire 2 being treated, generally within the region of the bead 6.

[0134] After the forming drum 14 begins to contract from its expanded state, as the protrusions 21 gradually slide toward the interior of the corresponding cavities 22, the segments approach each other in the circumferential direction CC. During the contraction of the forming drum 14 toward its contracted state, the terminal walls 25 of the inserts 23 are adapted to slidably interact with each other to help the inserts themselves gradually rotate toward a resting position against the action of the springs 28, which tend to elastically bring each insert 23 back toward its corresponding operating position.

[0135] In addition to or as an alternative to the interaction between the terminal walls 25, each insert 23 may have a cam portion 32, preferably formed as a lateral protrusion disposed proximal to one of the circumferentially opposite terminal walls 25 of the insert 23. The cam portion 32 may have a shape complementary to the axially outward protrusions 21 present between two circumferentially adjacent sectors 16, in order to impart greater continuity to the paving surface S in the region near the axial end edge 19 of the central body 18.

[0136] Each cam portion 32 can be arranged to interact with the central body 18 of the circumferentially adjacent sector 16 carrying the insert 23 itself, to facilitate the movement of the insert itself toward the rest position until the retracted state of the forming drum 14 is reached. For example, the cam portion 32 can interact with one of the protrusions 21 carried by the circumferentially adjacent sector 16. More specifically, at least in the operating position, the cam portion 32 of each insert 23 preferably approaches in an abutment relationship the radially inner surface of one of the protrusions 21 belonging to the axially outer part of the central body 18 of the sector 16 carrying the insert itself. As the forming drum 14 begins to retract from the expanded state, the action of the protrusions 21 on the cam portion 32 helps it to rotate against the action of the spring 28 about the axis of rotation YY defined by the corresponding pin 26 until it brings them into the rest position upon reaching the retracted state of the forming drum 14.

[0137] To construct tire 2, forming drum 14 from... Figure 2 The contraction state illustrated in the example expands radially to Figure 3 The illustrated expanded state is achieved by previously shrinking the forming drum, for example, to allow removal of the forming drum from a previously constructed tire.

[0138] Simultaneously with the expansion of the forming drum 14 from the contracted state to the expanded state, the insert 23, which was initially held in the resting position due to the interaction between the central body 18 and the cam portion 32, returns by the corresponding spring 28 and rotates about the rotation axis YY of the corresponding pin 26 until it is in the operating position when the radial expansion state of the forming drum 14 is reached.

[0139] The annular element 31 formed by a series of inserts 23 in the operating position, together with the central body 18 of the sector 16, helps to define the entire paving surface S. Such a paving surface can be defined, at least at the central body 18 of the sector 16. Figure 8 and Figure 9 The elastic membrane 35, indicated by the dashed line, extends circumferentially around the shaped drum 14.

[0140] The forming drum 14 in an expanded state is adapted to receive the tire carcass sleeve 12 and / or other components of the tire 2 being processed, which are connected to the forming drum itself via an application device 15.

[0141] The application of several components of the tire (e.g., the annular anchoring structure 5) may require the transmission of axial thrust at the axially opposite edges 20 of the forming drum 14, and the transmission of axial thrust with considerable influence and / or scale. Regarding such issues, the cooperation between the axial inner wall 24 of the insert 23 and the abutment surface 24a carried by the central body 18 of each sector 16 provides a wide contact surface suitable for effectively distributing the stress caused by the aforementioned axial thrust.

[0142] The application of components of the tire 2 can be completed in the forming station 13. Alternatively, it can be specified that the forming drum 14 carrying the tire carcass sleeve 12 and possibly other additional components is removed from the forming station 13 and the forming drum is transferred to one or more other workstations 33 for the application of other components, such as the belt structure 7, the tread belt 8, the sidewall 9 and / or other items.

[0143] At the end of the construction of at least one first tire 2, the forming drum 14 contracts radially to facilitate the removal of the same constructed tire.

[0144] The insert 23 of the forming drum 14 can be easily removed from the corresponding central body 18 and can be replaced with inserts 23 of different geometry and dimensional characteristics to adapt the forming drum 14 to the processing of tires 2 with different structural features. For this purpose, a retaining screw 27 can be applied to enable the removal and replacement of the insert 23. Such an operation can be conveniently performed without removing the pin 26, arm, and / or spring 28.

[0145] Preferably, the same forming drum 14 is configured to be coupled to multiple series of inserts 23. Each series of inserts 23 may individually and selectively engage with the central body 18 of the sector 16 to impart a predetermined geometry to the forming drum 14. In other words, the series of inserts 23 may be selectively interchangeable to adapt the forming drum 14 to the processing of tires 2 with different structural features.

[0146] Refer to the attached diagram. Figures 2 to 8 The insert 23 shown belongs to the first series of inserts 23. Figure 9In the example, inserts belonging to the second series are shown and labeled insert 23a, replacing inserts 23 belonging to the first series and engaging with the central body 18 of the corresponding sector 16. Inserts 23a belonging to the second series have different geometric and dimensional characteristics than inserts 23 belonging to the first series. More specifically, inserts 23a belonging to the second series have different axial extensions Z2 and / or radial extensions relative to inserts 23 belonging to the first series. In the example shown, inserts 23a belonging to the second series have a smaller axial extension Z2 than inserts 23 belonging to the first series. Engagement of inserts 23a belonging to the second series, replacing inserts belonging to the first series, thus allows for easy adaptation of the geometry and dimensional characteristics of the forming drum 14 to the handling of a carcass sleeve 12 in which one or more carcass ply layers 3 extend less in the cross-section including the annular anchoring structures 5 than the extensions that might be encountered when using inserts 23 belonging to the first series.

[0147] After the first tire 2, for example, obtained by using inserts 23 belonging to the first series, has been removed from the forming drum 14, the first series inserts 23 may be removed from the sector 16 and replaced with the second series inserts 23a if necessary before the application of the components of the second tire 2 with different structural features begins.

[0148] Any number of different inserts 23 can be specified to make the forming drum 14 flexible enough to suit different production needs. The availability of removable and interchangeable inserts 23 greatly simplifies the operation and production process, as well as the management of the testing process for implementing equipment and design specifications for manufacturing new tire types 2. Inserts 23 are, in fact, components that can be manufactured in a limited time and at a relatively low cost. The fact that inserts 23 can be easily replaced thus allows the geometry and size of the forming drum 14 to be changed to a certain extent as required to adapt it to new production needs or for testing new configurations, significantly reducing time, design, and implementation costs.

Claims

1. A method for constructing a tire, the method comprising: An expandable annular forming drum (14) is arranged, the forming drum comprising circumferentially successive segments (16) capable of radial movement, each of the segments comprising a central body (18) and a pair of interchangeable inserts (23), each of the inserts being removably engaged at a corresponding axial end edge (19) of the central body (18). The forming drum (14) is expanded from a contracted state to an expanded state, in which the sector (16) moves closer to the geometric axis of rotation (XX) of the forming drum (14), and in the expanded state, the sector (16) moves radially away from the geometric axis of rotation (XX) in order to define a radially outward laying surface (S) extending between two axially opposite edges (20) of the forming drum (14). At least one component of the treated first tire is applied to the laying surface (S) of the forming drum (14); During the expansion of the forming drum (14), the insert (23) of each segment (16) moves relative to the corresponding central body (18) to an operating position by rotating about a rotation axis (YY) about a placement plane that extends axially through the respective axial end edge (19) of the central body (18). In the operating position, each insert (23) extends on a continuous portion of the insert (23) belonging to the circumferentially adjacent segments (16) to form an annular element (31) extending along the axially opposite edges (20) of the forming drum (14).

2. The method according to claim 1, wherein, The insert (23) forms a first series of inserts, wherein, after the first tire being treated is removed, the first series of inserts are removed from the sector (16) of the forming drum (14), and the first series of inserts are replaced with inserts (23a) belonging to a second series, which have different dimensions from the first series of inserts, before at least one component of the second tire being treated is applied to the laying surface (S) of the forming drum (14).

3. The method according to claim 1 or 2, wherein, The insert (23) is brought from the rest position to the operating position, in which each insert extends transversely in a circumferential direction (CC) concentric with the geometric axis of rotation (XX) relative to the forming drum (14).

4. The method according to claim 1 or 2, wherein, In the operating position, the inserts (23) arranged along each of the axial opposite edges (20) of the forming drum (14) extend in a circumferential direction (CC) concentric with the geometric axis of rotation (XX) of the forming drum (14) in such a manner as one insert on the continuity of another insert.

5. The method according to claim 1 or 2, wherein, In the operating position, each of the corresponding circumferential relative terminal walls (25) of each insert (23) engages with one of the terminal walls (25) of the circumferentially adjacent insert (23).

6. The method according to claim 1 or 2, wherein, Each insert (23) is elastically pushed into the operating position.

7. The method according to claim 1 or 2, wherein, During the contraction of the forming drum (14), each insert (23) is pushed to a rest position by the protrusion (21) belonging to the adjacent sector (16), which acts on the cam portion (32) carried by the insert itself.

8. The method according to claim 1 or 2, wherein, The at least one component is applied by an axial thrust acting on the axially opposite edges (20) of the forming drum (14).

9. The method according to claim 8, wherein, Each insert (23) has an axial inner wall (24) that acts axially on the central body (18) in an abutment relationship to resist the axial thrust transmitted to the forming drum (14) during the application of the insert.

10. The method according to claim 1 or 2, the method further comprising the actions of radially retracting the forming drum (14) after applying the at least one component and removing the treated first tire from the forming drum (14).

11. An apparatus for constructing a tire for a vehicle wheel, the apparatus comprising: An expandable annular forming drum (14) having a radially outwardly laid surface (S) extending between two axially opposite edges (20) of the forming drum (14). An application device (15) is used to apply the components of the tire being processed onto the laying surface (S) of the forming drum (14); The forming drum (14) includes: Circumferentially successive sector segments (16) are capable of radial movement between a contracted state and an expanded state. In the contracted state, the sector segment (16) moves closer to the geometric rotation axis (XX) of the forming drum (14), and in the expanded state, the sector segment (16) moves radially away from the geometric rotation axis (XX) in order to define the laying surface (S). Each sector (16) includes a central body (18) and a pair of interchangeable inserts (23), each of which is removably engaged at a corresponding axial end edge (19) of the central body (18). Each insert (23) is rotatably engaged with the central body (18) by a pin (26) extending axially through the corresponding axial end edge (19) of the central body (18). The insert (23) is capable of moving simultaneously with the expansion of the forming drum (14) from the contracted state to the expanded state until reaching the operating position, in which each insert extends on a continuous portion of the insert (23) belonging to the circumferentially adjacent sector (16) to form an annular element (31) extending along the axially opposite edge (20) of the forming drum (14).

12. The device according to claim 11, wherein, Each sector (16) has a central body (18) that carries circumferentially opposite connecting parts (18a, 18b).

13. The device according to claim 12, wherein, Each of the connecting portions (18a, 18b) includes a circumferential protrusion (21) that alternates with the circumferential cavity (22).

14. The device according to claim 13, wherein, The protrusion (21) of each sector (16) is slidably engaged in the corresponding cavity (22) of the circumferentially adjacent sector (16).

15. The device according to any one of claims 11 to 14, wherein, The central body (18) of each sector (16) is axially defined between two opposing axial end edges (19).

16. The device according to claim 15, wherein, The axial end edges (19) are spaced apart from each other to a degree less than the total axial dimension of the paved surface (S).

17. The device according to claim 15, wherein, Each of the axial end edges (19) is spaced apart from one of the axial opposite edges (20) of the forming drum (14).

18. The device according to any one of claims 11 to 14, the device comprising a series of inserts having different sizes, each series of inserts being individually and selectively engaged with the central body (18) of the sector (16) to impart a predetermined geometry to the forming drum (14).

19. The device according to any one of claims 11 to 14, wherein, The annular element (31) defines the axial outer portion of the laid surface (S).

20. The device according to any one of claims 11 to 14, wherein, The insert (23) is movable from the rest position toward the operating position, in which each insert extends transversely in a circumferential direction (CC) concentric with the geometric axis of rotation (XX) relative to the forming drum (14).

21. The device according to any one of claims 11 to 14, wherein, Each insert (23) has an elongated curved shape along the basic circumferential direction (CC).

22. The device according to any one of claims 11 to 14, wherein, In the operating position, each insert (23) extends along a circumferential direction (CC) concentric with the geometric axis of rotation (XX).

23. The device according to any one of claims 11 to 14, wherein, In the operating position, the inserts (23) arranged along each of the axial opposite edges (20) of the forming drum (14) extend in a circumferential direction (CC) concentric with the geometric axis of rotation (XX) of the forming drum (14) in such a manner as one insert on the continuity of another insert.

24. The device according to any one of claims 11 to 14, wherein, Each insert (23) is removably connected to the pin (26) by a retaining screw (27) that engages coaxially with the pin itself.

25. The device according to any one of claims 11 to 14, wherein, Each insert (23) is elastically pushed into the operating position.

26. The device according to any one of claims 11 to 14, wherein, Each insert (23) is elastically pushed toward the operating position by at least one spring (28) operating between the central body (18) of the corresponding sector (16) and the insert itself.

27. The device according to claim 26, wherein, One end of the spring (28) is constrained to an arm (29) that protrudes radially from the pin (26).

28. The device according to claim 12 or 13, wherein, Each insert (23) is elastically pushed toward the operating position by at least one spring (28) operating between the central body (18) of the corresponding sector (16) and the insert itself, wherein one end of the spring (28) is constrained to an arm (29) that protrudes radially from the pin (26), wherein the arm (29) is located at a radially inward position at one of the connecting portions (18a, 18b), next to one of the protrusions (21).

29. The device according to any one of claims 11 to 14, wherein, Each insert (23) has an axial inner wall (24) pointing to the central body (18) of the corresponding sector (16).

30. The device according to claim 29, wherein, The axial inner wall (24) is substantially flat.

31. The device according to claim 29, wherein, The axial inner wall (24) acts in an abutting relationship on the abutting surface (24a) carried by the central body (18) of the corresponding sector (16) at the corresponding axial end edge (19).

32. The device according to claim 31, wherein, The contact surface (24a) is substantially flat.

33. The device according to claim 31, wherein, The axial inner wall (24) of the insert (23) and the abutting surface (24a) are slidably engaged in a plane orthogonal to the geometric axis of rotation (XX) of the forming drum (14).

34. The device according to claim 11, wherein, Each insert (23) has a curved longitudinal extension between at least two terminal walls (25) that are circumferentially opposite each other.

35. The device according to claim 34, wherein, In the operating position, each of the terminal walls (25) of each insert (23) is close to one of the terminal walls (25) of the circumferentially adjacent inserts (23).

36. The device according to claim 34, wherein, In the operating position, each of the terminal walls (25) of each insert (23) mates with one of the terminal walls (25) of the circumferentially adjacent insert (23).

37. The device according to claim 34, wherein, At least in the operating position, each of the terminal walls (25) of each insert (23) is parallel to one of the terminal walls (25) of the circumferentially adjacent inserts (23).

38. The device according to claim 34, wherein, The terminal wall (25) is arranged in an extended manner that is inclined relative to the radial direction (R) at the geometric axis of rotation (XX) of the forming drum (14).

39. The device according to any one of claims 34 to 38, wherein, In the operating position, the terminal wall (25) forms an angle between 15° and 60° with respect to the radial direction (R) at the geometric axis of rotation (XX) of the forming drum (14).

40. The device according to claim 34, wherein, Each insert (23) has a cam portion (32) obtained in the form of a lateral protrusion, the cam portion being arranged on one of the proximal sides of the circumferentially opposite terminal wall (25) of the insert itself.

41. The device according to claim 34, wherein, Each insert (23) has a cam portion (32) having a shape that is spatially complementary to the axially outward protrusions (21) belonging to two circumferentially adjacent sectors (16).

42. The device according to claim 34, wherein, Each insert (23) has a cam portion (32) configured to interact with the central body (18) of one of the circumferentially adjacent sectors (16).

43. The device according to any one of claims 40 to 42, wherein, The cam portion (32) is provided as a lateral protrusion, which is arranged on one of the circumferentially opposite terminal walls (25) of the insert (23) to interact with one of the protrusions (21) carried by the sector (16) that is circumferentially adjacent to the sector carrying the insert (23) itself.

44. The device according to any one of claims 40 to 42, wherein, At least in the operating position, the cam portion (32) of each insert (23) approaches the radial inner surface of one of the axially outer protrusions (21) of the central body (18) of the sector (16) adjacent to the sector carrying the insert (23) itself.

Images