WO2025093985A1

WO2025093985A1 - Method and apparatus for manufacturing stratified annular components in the manufacturing of tyres

Info

Publication number: WO2025093985A1
Application number: PCT/IB2024/060238
Authority: WO
Inventors: Christian De Col; Cristiano Puppi; Stefano Sangiovanni
Original assignee: Pirelli SpA; Pirelli Tyre SpA
Current assignee: Pirelli and C SpA; Pirelli Tyre SpA
Priority date: 2023-11-02
Filing date: 2024-10-18
Publication date: 2025-05-08
Anticipated expiration: 2026-05-02

Abstract

In the manufacturing of a tyre for vehicles, one or more stratified annular components are obtained, by arranging, around a central geometric axis (X), a radially outer annular layer (7a) with toroidal shape having a concavity directed towards the central geometric axis (X). Against the radially outer annular layer (7a), a radially inner annular layer (7b) with toroidal shape is then applied, having a convexity directed away from the central geometric axis (X). Before applying the radially inner annular layer (7b), axially opposite end flaps (26) of the radially outer layer (7a) are mutually moved apart.

Description

METHOD AND APPARATUS FOR MANUFACTURING STRATIFIED ANNULAR COMPONENTS IN THE MANUFACTURING OF TYRES

The present invention relates to a method for manufacturing stratified annular components in the manufacturing of tyres. The present invention also relates to an apparatus for manufacturing stratified annular components in the building of tyres for vehicles. In the example described herein, the invention is employed for manufacturing a belt structure for tyres of motor vehicles. The invention is nevertheless conveniently employable also for the manufacturing of annular tyre components different from the belt structure and employable not only on tyres for motor vehicles, but also for cars, trucks, etc..

A tyre for vehicle wheels generally comprises a carcass structure comprising at least one carcass ply having respectively opposite end flaps engaged with respective anchoring annular structures, integrated in the zones normally identified with the name "beads", having an inner diameter substantially corresponding to a so-called "fitting diameter" of the tyre on a respective mounting rim.

The carcass structure is associated with a belt structure that can comprise one or more belt layers, situated in radial superimposition with respect to each other and with respect to the carcass ply, having textile, metal or hybrid reinforcement cords with cross orientation and/or orientation substantially parallel to the circumferential extension direction of the tyre (at 0 degrees). In radially outer position with respect to the belt structure, a tread band is applied, it too made of elastomeric material such as other constituent semifinished products of the tyre.

Respective sidewalls made of elastomeric material can also be applied in axially outer position on the lateral surfaces of the carcass structure, each extended from one of the lateral edges of the tread band up to the respective anchoring annular structure to the beads. In the tyres of "tubeless" type, an air impermeable covering layer, normally termed "liner", covers the inner surfaces of the tyre.

The terms "radial" and "axial" and the expressions "radially inner/outer" and "axially inner/outer" are used with reference to the radial direction and to the axial direction of the tyre, i.e. to a direction perpendicular to the rotation axis of the tyre and to a direction parallel to the rotation axis of the same, respectively. A radial plane of the tyre contains the rotation axis of the same.

The terms "circumferential" and "circumferentially" are instead used with reference to the annular extension of the tyre by identifying, with such expression, the extension taken on by the tyre along the rolling direction in operating conditions.

By "rotation axis" of a green tyre it is intended the axis corresponding to the rotation axis of the moulded and vulcanised tyre when mounted in operating conditions on a respective mounting rim.

With the term "component" of the tyre it is intended any one portion of the tyre capable of carrying out its own function or being a part thereof.

With the term "stratified annular component" of the tyre, it is intended a component of the tyre comprising a plurality of radially opposite layers with respect to rotation axis of the tyre, in which said plurality of layers comprises at least one radially outer annular layer and one radially inner annular layer and in which each layer comprises at least one matrix of elastomeric material. Preferably, a stratified annular component of the tyre can be set comprising two or more belt layers and in particular can be a belt structure or, more generally, a stratified annular component can be a set comprising two or more layers intended to constitute part of the green tyre, each selectable for example between: liner, under-liner, carcass ply/plies, belt layer/layers, belt underlayer, underlayer of the tread band, sidewalls, sidewall inserts, tread band, etc..

With the term "elastomeric material" it is intended to indicate a composition comprising at least one elastomeric polymer and at least one reinforcement filler. Preferably, such composition also comprises additives such as, for example, a crosslinking agent and/or a plasticiser. Due to the presence of the crosslinking agent, through heating such material, it can be crosslinked, so as to form the final manufactured item.

With the term "semifinished product" it is intended a prefabricated manufactured item, i.e. a manufactured item fabricated before the production of the tyre and generally outside the building plant. The manufactured item is preferably prefabricated at full width, i.e. with a pre-sized width of the layer of the component that the semifinished product is adapted to form. The semifinished product can be made only of elastomeric material i.e. comprise only one elastomeric matrix or it can be reinforced with at least one reinforcement cord made of textile and/or metallic and/or hybrid material. By "tyre for vehicles with two wheels", in particular motorcycles, it is intended a tyre whose curvature ratio is approximately comprised between about 0.15 and about 0.45.

By "curvature ratio" relative to a tyre (or to a portion thereof or to a drum) it is intended the ratio between the distance of the radially outer point of the tread band (or of the outer surface or of the drum) from the line passing through the laterally opposite ends of the tread itself (or of the outer surface itself or of the drum), measured on a radial plane of the tyre (or of said portion thereof or of the drum) i.e. on a plane containing the rotation axis thereof (of the same or of the drum), and the distance measured along the cord of the tyre (or of a portion thereof or of the drum) between said ends.

The Applicant has observed that the building of a green tyre generally provides for the manufacturing of at least one stratified annular component by superimposed deposition of two or more annular layers starting from the radially inner annular layer towards the radially outer annular layer.

For example, in the document WO 2021/124241, in the name of the same Applicant, a process is described for manufacturing belt structures according to which, on a cylindrical drum, a first and a second belt layer are deposited. The belt layers are subsequently removed from the cylindrical drum and engaged on a further drum of toroidal shape by an annular grip member equipped with circumferentially adjacent and radially movable angular sectors. Around the toroidally shaped belt layers, a belt layer so-called at zero degrees is then attained, obtaining by winding one or more cords according to turns that are circumferentially and axially side-by-side, so as to obtain the desired configuration of the set of belt layers.

In the document US 4,288,265, a process is described for building tyres, in which the manufacturing of a belt structure provides that a first and a second semifinished product in strip form are wound in succession around an auxiliary drum of the type having a plurality of axial teeth circumferentially distributed to define a substantially cylindrical surface. The auxiliary drum houses an expandable part composed of a plurality of sectors, each having a convex radially outer surface. The sectors are radially movable between the teeth of the drum between a rest position in which they are radially arranged with their entire convex surface within the cylindrical surface defined by the drum itself, and a work position in which they radially project between the teeth of the drum so as to impose - on the annular layers previously formed thereon - a toroidal shape according to a convex axial profile. An annular transfer ring equipped with radially movable sectors is adapted to transfer the belt structure formed on the auxiliary drum to a primary drum, for the purposes of coupling with a carcass structure.

The Applicant has observed that the radial expansion of the previously-coupled semifinished products, for their toroidal shaping, can determine the presence of high stresses that are generated at the interface between two radially adjacent layers, due to the mutual adhesion between such layers and to the different expansion between the axially peripheral portions and the axially central portion of the stratified component. These stresses can generate differentiated narrowing and widening in the material, giving rise to imperfections such as bends and/or non-alignment of the edges, above all when one or more layers incorporate reinforcement cords arranged parallel to each other and cross with respect to those of at least one annular layer that is radially adjacent which, during the radial expansion, tend to rotate in respectively opposite senses even if remaining incorporated in the elastomeric matrix.

The Applicant has also verified that the above is particularly evident in the manufacturing of tyres with a high curvature ratio, as is for example typically seen in tyres for vehicles with two wheels. In other words, the Applicant has established that the above-listed problems, which affect the actual and constant reproducibility of the footprint area on the ground, prefigured in design step, are more significant in those tyres where higher behaviour reliability is required in order to be able to obtain high driver safety.

With the goal of seeking to limit the imperfections detected following the shaping of a stratified component, the Applicant has perceived on one hand the importance of the stresses tied to the interaction between the layers themselves and on the other hand the limited margin of improvement available in focusing the attention on the interface between two radially adjacent layers in order to improve the interaction thereof.

The Applicant has therefore understood that a different approach was necessary for building the stratified component in order to decouple the layers during shaping. According to the Applicant, indeed, by reversing the order of arrangement of the layers, i.e. by starting from the radially more external layer, it is possible to shape each layer in a manner independent from the others so as to exclude each behaviour tied to the effect operated by the presence of multiple layers, actually cancelling those imperfections due to their interaction.

The Applicant has however verified that by actuating the coupling between the shaped superimposed layers, it could be difficult to determine the correct application of the radially more internal layer against the radially more external layer, without there occurring mechanical interferences between the surfaces of the layers themselves.

The Applicant has in fact observed that, above all when the layers are shaped according to a toroidal profile with an accentuated curvature ratio, the surfaces of both layers can prematurely come into contact with each other at the axially outer flaps during the mutual approach, determining the risk of of generating creases and structural imperfections.

The Applicant has finally found that the coupling between the layers is significantly facilitated if the axially opposite end flaps of the radially more external layer are slightly moved away from each other before the contact occurs with the radially more internal layer during approaching.

More particularly, according to a first aspect, the present invention relates to a method for manufacturing stratified annular components in the manufacturing of tyres for vehicles. Preferably, provision is made for arranging, around a central geometric axis, a radially outer annular layer with toroidal shape having a concavity directed towards the central geometric axis.

Preferably, provision is made for moving, mutually apart, axially opposite end flaps of the radially outer layer, before internally applying a subsequent annular layer to said radially outer annular layer.

According to a further aspect, the present invention relates to an apparatus for manufacturing stratified annular components in the building of tyres for vehicles.

Preferably, an annular retention member with toroidal shape is provided for, having a concavity directed towards the central geometric axis.

Preferably, application devices are provided, comprising a profiler drum with toroidal shape having a convexity directed away from the central geometric axis.

Preferably, the annular retention member comprises two axially opposite retention annular portions, each directed towards the central geometric axis.

Preferably, the retention annular portions movable with respect to each other.

The Applicant deems that the mutual moving apart of the end flaps facilitates the insertion of the radially inner annular layer in the absence of interferences and sliding against the inner surfaces of the radially outer annular layer. The coupling is therefore facilitated, even when the annular layers are initially shaped identical to each other, for example by aid of a same profiler drum.

In at least one of the aforesaid aspects, the invention can also conveniently comprise one or more of the following preferred characteristics.

Preferably, provision is made for internally applying, against the radially outer annular layer, a radially inner annular layer with toroidal shape having a convexity directed away from the central geometric axis.

Preferably, said subsequent annular layer is a radially inner annular layer with toroidal shape having a convexity directed away from the central geometric axis.

Preferably, an initial contact between the radially inner annular layer and the radially outer annular layer occurs in proximity to an axial middle line plane equidistant from said axially opposite end flaps of the radially outer layer.

Preferably, the axially opposite end flaps of the radially outer layer are mutually moved apart up to reaching a mutual second axial distance not less than a reference distance detectable between axially opposite end flaps of the radially inner annular layer.

Preferably, said second axial distance and said reference distance are measurable parallel to the central geometric axis.

Preferably, said second axial distance is detectable along a first axial direction traversing said axial middle line plane.

Preferably, said reference distance is detectable along a second axial direction traversing an axial middle line plane equidistant from the axially opposite end flaps of the radially inner annular layer.

Preferably, a first radial distance detectable between a radially inner surface of the radially outer annular layer and an intersection of the axial middle line plane with the first axial direction, is equal to a second radial distance detectable between a radially outer surface of the radially outer annular layer, and an intersection of the axial middle line plane with the second axial direction.

Preferably, during the moving apart action, a radial section of the radially outer annular layer is switched from a first configuration in which the axially opposite end flaps of the radially outer annular layer are arranged at a first axial distance, to a second configuration in which the same end flaps are arranged at a second axial distance greater than the first axial distance.

Preferably, provision is also made for the action of reapproaching the axially opposite end flaps of the radially outer annular layer at the end of the application of the radially inner annular layer.

Preferably, the reapproaching of the axially opposite end flaps of the radially outer annular layer is executed while the radially inner annular layer is positioned against the radially outer annular layer at least at an axial middle line plane substantially equidistant from the end flaps themselves.

Preferably, following the reapproaching, the axially opposite end flaps of the radially outer annular layer come into contact with the radially inner annular layer.

Preferably, arranging the radially outer annular layer comprises: depositing the radially outer annular layer according to a substantially cylindrical shape around the central geometric axis; expanding, within the radially outer annular layer, a profiler drum having an expansion surface that is radially outer and axially convex, in order to toroidally shape the radially outer annular layer.

Preferably, applying the radially inner annular layer comprises: depositing the radially inner annular layer according to a substantially cylindrical shape around the central geometric axis; expanding, within the radially inner annular layer, a profiler drum having an expansion surface that is radially outer and axially convex, in order to toroidally shape the radially inner annular layer.

Preferably, an initial contact between the radially inner annular layer and the radially outer annular layer occurs simultaneously with the attainment of a condition of maximum expansion of said profiler drum.

Preferably, provision is also made for the action of retaining the radially outer annular layer at a radially outer surface thereof during the application of the radially inner annular layer.

Preferably, the action of retaining the radially outer annular layer is executed by attraction forces exerted through an annular retention member.

Preferably, the attraction forces are generated by a suction action.

Preferably, the mutual moving apart of the axially opposite end flaps of the radially outer annular layer is executed by mutual moving away of two axially opposing retention annular portions of the annular retention member.

Preferably, the retention annular portions operate, each against one of the axially opposite end flaps of the radially outer annular layer.

Preferably, the retention annular portions are axially movable on command of one or more axial movement actuators.

Preferably, each of the retention annular portions has suction ducts leading to respective openings that are distributed and directed towards the central geometric axis.

Preferably, the annular retention member comprises a plurality of grip elements that are circumferentially distributed around the central geometric axis.

Preferably, said grip elements are radially movable with respect to the central geometric axis.

Preferably, each of the retention annular portions comprises a plurality of circumferentially distributed retention blocks.

Preferably, each of said grip elements comprises two retention blocks that are axially side-by-side each other, each belonging to one of said retention annular portions.

Preferably, each of said grip elements comprises a support element carrying said retention blocks.

Preferably, the retention blocks of each grip element are axially slidable with respect to the respective support element.

Preferably, the retention blocks belonging to each grip element are axially movable in mutual approach and moving apart.

Preferably, the retention blocks belonging to each grip element are mutually interconnected by a threaded bar actuatable in rotation by said axial movement actuator.

Preferably, the axial movement actuator is a rotary actuator.

Preferably, the rotary actuator is fixed to the respective support element.

Preferably, the threaded bar has a right-hand thread and a lefthand thread respectively engaged with the retention blocks.

Preferably, the annular retention member comprises a support structure arranged circumferentially around the central geometric axis.

Preferably, the support structure is movable parallel to the central geometric axis.

Preferably, the support structure is slidably mounted on one or more linear guides.

Preferably, the support structure has substantially plate-like configuration arranged according to a plane orthogonal to the central geometric axis.

Preferably, the support structure is equipped with a central opening.

Preferably, the annular retention member comprises one or more radial movement actuators carried by the support structure and operating on said support elements.

Preferably, said profiler drum can be positioned coaxial to the central geometric axis in axially centred position with respect to the annular retention member, and switchable from a radially contracted condition to a radially expanded condition.

Preferably, the profiler drum has an expansion surface that is radially outer and axially convex.

Preferably, said application devices also comprise a building drum, coaxial with the central geometric axis in axially centred position with respect to the annular retention member, and comprising two half-drums that are axially adjacent in order to define a substantially cylindrical deposition surface.

Preferably, said application devices also comprise at least one feeder configured for applying semifinished products around the deposition surface of the building drum.

Preferably, the building drum is switchable between a deposition condition in which respective terminal edges, axially directed towards each other, of the half-drums are mutually approached, and a shaping condition in which said terminal edges are mutually spaced.

Preferably, in the radially expanded condition, the profiler drum projects radially through an annular opening axially delimited between the terminal edges of the half-drums in the shaping condition.

Preferably, said annular retention member is configured for retaining, around said central geometric axis, a radially outer annular layer.

Preferably, said profiler drum is configured for applying, internally against the radially outer annular layer, a radially inner annular layer.

Preferably, said two retention annular portions are configured for operating against the radially outer annular layer.

Preferably, said retention annular portions are axially movable with respect to each other.

Preferably, said profiler drum is switchable from said radially contracted condition to said radially expanded condition in order to carry the radially outer annular layer against the retention annular portions.

Further characteristics and advantages will be clearer from the detailed description of a preferred but non-exclusive embodiment of a method and an apparatus for manufacturing stratified annular components in the building of tyres for vehicles, in accordance with the present invention.

Such description will be set forth hereinbelow with reference to the enclosed drawings, provided only as a non-limiting example, in which:

- figures 1-13 schematically illustrate several elements of an apparatus for manufacturing stratified annular components in the building of tyres for vehicles, at different moments of a building process;

- figure 14 schematically illustrates a layout of a plant for building a green tyre equipped with the apparatus according to the present invention;

- figure 15 schematically shows, in radial half-section, a tyre that can be manufactured in accordance with the present invention. With reference to figure 14, 1 overall indicates a plant for building green tyres.

The plant 1 is set for manufacturing green tyres 2 (figure 15) comprising at least one carcass ply 3 preferably internally covered by a layer of impermeable elastomeric material or so- called liner 4. Two anchoring annular structures 5, each comprising a so-called bead core 5a preferably carrying an elastomeric filler 5b in radially outer position, are engaged with respective end flaps 3a of the carcass ply/plies 3. The anchoring annular structures 5 are integrated in proximity to zones normally identified with the name "beads" 6, at which the engagement between the tyre 2 and a respective mounting rim (not depicted) usually occurs.

A crown structure comprises at least one belt structure 7 and a tread band 8 circumferentially superimposed on the belt structure 7. The crown structure is circumferentially arranged around the carcass ply/plies 3.

The belt structure 7 comprises at least two layers: a radially outer belt layer 7a and a radially inner belt layer 7b. Possibly, one or more further belt layers can be provided that are radially intermediate between the radially outer belt layer 7a and the radially inner belt layer 7b.

The belt layers can comprise parallel textile and/or metallic and/or hybrid cords, preferably arranged according to an orientation that is tilted with respect to the circumferential extension direction of the green tyre 2 and respectively cross between belt layers that are adjacent to each other.

The tyre 2 also comprises two sidewalls 9, each extended from the corresponding bead 6 to a corresponding lateral edge of the tread band 8, applied in positions laterally opposite the carcass ply/plies 3.

The tyre 2 can also comprise further elements as a function of the use destination.

Preferably this is a tyre for motorcycles or other two-wheel vehicles having curvature ratio approximately comprised between about 0.15 and about 0.45.

The plant 1 (figure 14) is equipped with an apparatus for manufacturing stratified annular components in the building of tyres for vehicles, according to the present invention. In the example described and illustrated herein, such apparatus is represented by a belt structure building station overall indicated with 11, cooperating with a carcass structure building station 10 and an assembly station 38. The belt structure 7 therefore represents, in the illustrated example, a stratified annular component attainable by the apparatus represented by the belt structure building station 11. The radially outer belt layer 7a and the radially inner belt layer 7b respectively represent a radially outer annular layer and a radially inner annular layer constituting part of the stratified annular component. The belt structure 7 can possibly have one or more intermediate belt layers (not illustrated), radially interposed between the radially outer belt layer 7a and the radially inner belt layer 7b, and representing respective annular intermediate layers interposed between the radially outer annular layer and the radially inner annular layer constituting part of the stratified annular component.

In the course of the present description, each reference to the belt structure building station 11 and to the belt structure 7 will be intended as applied also to the apparatus for manufacturing stratified annular components and to each stratified annular component obtainable therewith. Analogously, each reference to the radially outer belt layer 7a, to the radially inner belt layer 7b and/or to each possible intermediate belt layer will be intended as applied respectively to the radially outer annular layer, to the radially inner annular layer and/or to each possible intermediate annular layer constituting part of the stratified annular component.

The carcass structure building station 10 is adapted to attain, for example according to known modes, a carcass sleeve 12 (figure 14) having substantially cylindrical shape. The carcass sleeve 12 comprises said at least one carcass ply 3, preferably internally covered by the liner 4, and having the respective end flaps 3a engaged, for example through up-turning, with the respective anchoring annular structures 5. If necessary, the carcass sleeve 12 can also comprise the sidewalls 9 or first portions thereof, each extended starting from a respective bead 6.

The belt structure building station 11 is adapted for attaining the belt structure 7 comprising at least the radially outer belt layer 7a and the radially inner belt layer 7b, as well as, if requested, one or more of the intermediate belt layers not present in the described and illustrated embodiment.

With reference to figures 1-13, the belt structure building station 11 has application devices which comprise a profiler drum 17 and, preferably, a building drum 13 coaxially rotating around a central geometric axis X which, with reference to the tyre 2, corresponds with a rotation axis of the tyre itself. The building drum 13 has a cylindrical radially outer surface, not necessarily continuous, defining a deposition surface 14 arranged around the central geometric axis X.

The building drum 13 comprises two half-drums 15 that are movable with respect to each other in axial direction along the central geometric axis X in order to mutually move close to and away from each other. Preferably each half-drum 15 comprises a slide preferably in flange form 15a having discoid shape, on which deposition sectors 15b are mounted that are circumferentially distributed around the asse X. The deposition sectors 15b have respective axially inner ends directed towards an axial middle line plane M. In order to simplify the illustration, figures 1-13 report only one deposition sector 15b for each halfdrum 15. In each of the half-drums 15, the deposition sectors 15b are axially movable with respect to the respective flange 15a away from and closer to axial middle line plane M of the building drum 13. The building drum 13 is thus switchable between a deposition condition, in which respective terminal edges, axially directed towards each other, of the half-drums 15 are mutually approached, and a shaping condition in which said terminal edges are mutually spaced. At least in the deposition condition, i.e. in an approached position of the two half-drums 15 and of the deposition sectors 15b, the deposition sectors 15b define the deposition surface 14.

The axial moving of the deposition sectors 15b away from the axial middle line plane M, towards the open condition, creates and/or enlarges an annular opening 16 (figures 4-7 and 11-13) arranged centrally with respect to the deposition surface 14. Preferably, the slides or flanges 15a are movable mutually apart, in order to switch the building drum 13 into an open condition in which the half-drums 15 are mutually moved apart according to a size greater than the shaping condition. The mutual and preferably symmetric moving apart of the two half-drums 15, in particular of the two flanges 15a, allows the access to the zone within the building drum 13.

When the two half-drums 15 are mutually moved apart with the building drum 13 in the open condition, the profiler drum 17 can be inserted through the annular opening 16 inside the building drum 13 and mounted coaxial therewith, as is for example illustrated in figures 1-13 and, still through the annular opening 16, it can be extracted from the building drum 13 and moved away therefrom as illustrated in figure 14.

The profiler drum 17 comprises a profiler body 18 having a radially outer surface, not necessarily continuous, defining a radially outer expansion surface 19, arranged around the central geometric axis X. The expansion surface 19 is axially convex, according to an axial profile corresponding to the axial profile of the belt structure 7 such that the belt structure 7 has a toroidal shape. An axial plane of symmetry of the expansion surface 19 is axially centred with respect to the axial middle line plane M.

Preferably the profiler body 18 comprises profiler sectors 18a circumferentially distributed around a central shaft 20 of the profiler drum 17 and defining the expansion surface 19. For ease of illustration, figures 1-13 report only one profiler sector 18a.

Movement members 22 allow a simultaneous radial movement of the sectors 18, such that the profiler drum 17 can be radially expanded and contracted between a first operative condition, radially contracted (e.g. illustrated in figures 1 and 2), so as to have a maximum diameter thereof smaller than or equal to a diameter of the deposition surface 14, and a second operative condition, radially expanded (e.g. illustrated in figures 3-7) to a maximum diameter greater than the diameter of the deposition surface 14, so as to project radially through the annular opening 16.

Preferably the profiler drum 17, and in particular the expansion surface 19, at least in the second operative condition has a curvature ratio comprised between about 0.15 and about 0.45, typically suitable for manufacturing tyres for motorcycles or other two-wheel vehicles. If necessary, curvature ratios of different values can be employed, for example lower than those indicated above, e.g. suitable for the production of car or truck tyres.

Further technical details of the movement members 22 and of the sectors 18a are not described since they can be attained in various ways, not relevant for the purposes of the invention. For example, technical solutions can be used of the type employed on a forming drum, used for shaping a carcass structure in the patent US 10,611,110 B2, in the name of the same Applicant, which is considered fully reported hereinbelow.

With reference to figure 14, the belt structure building station 11 is associated with an annular retention member 23 which comprises a support structure 24 arranged circumferentially around the central geometric axis X. In one embodiment, the support structure 24 (schematically represented) has substantially plate-like configuration arranged according to a plane orthogonal to the central geometric axis X and equipped with a central opening circumscribing the building drum 13 and the profiler drum 17. The support structure 24 is preferably slidably mounted on one or more linear guides 25 (figure 14), in order to allow the translation of the support structure 24 parallel to the central geometric axis X.

With reference for example to figure 1, on the support structure 24, a plurality of grip elements 26 are mounted that are circumferentially distributed around the central geometric axis X. For ease of illustration, figures 1-13 report only one grip element

26.

Each grip element 26 comprises a pair of retention blocks 27 that are axially side-by-side each other, preferably slidably engaged in axial direction - i.e. parallel to the central geometric axis X - in radially inner position with a support element 28.

The retention blocks 27 belonging to each grip element 26 are mutually interconnected by a threaded bar 29 actuatable in rotation by at least one axial movement actuator 30, preferably a rotary actuator fixed to the respective support element 28. The threaded bar 29 has a right-hand thread 29a and a left-hand thread 29b respectively engaging each of the retention blocks

27. Upon an actuation of the axial movement actuator 30, in one direction or in the other, there respectively corresponds a mutual axial approaching or moving apart of the retention blocks 27 in a symmetric manner with respect to the axial middle line plane M. Each of the grip elements 26 is preferably radially movable between a first position in which it is moved close to the central geometric axis X (e.g. illustrated in figure 7) and a second position in which it is moved away from the central geometric axis X (e.g. illustrated in figure 1). The radial movement of the grip elements 26 is mechanically actuatable (e.g. by a toothed ring nut, a cam system and/or arms system) and/or hydraulically actuatable, e.g. by one or more radial movement actuators 31 carried by the support structure 24 and operating on the support elements 28. In the illustrated example, a radial movement actuator radiale 31 is provided for each of the grip elements 26. Each of the retention blocks 27 has, in radially inner position, a grip surface 32 having curved profile, directed towards the central geometric axis. The grip surfaces 32 of all the retention blocks 27 are adapted to define, overall, an annular retention surface, not necessarily continuous, arranged concentrically with respect to the central geometric axis X-X and having a section profile that is symmetrically curved with respect to the axial middle line plane M. The groups of retention blocks 27 that are circumferentially distributed on one side and respectively on the other side of the axial middle line plane M define respective retention annular portions 27a that are axially opposite with respect to each other, and each of which corresponds with a half-part of the annular treatment surface. In the annular treatment surface, two half-parts are therefore identifiable that are axially opposite with respect to the axial middle line plane M. The activation of the axial movement actuators 30 determines a mutual axial movement of the retention annular portions 27a.

The annular retention member 23 is preferably equipped with a retention system, preferably by vacuum, e.g. a sucker and/or suction system. Such ducts 33 can for example be provided in each of the retention blocks 27, such suction ducts 33 leading to respective openings distributed on the respective grip surfaces 32 and directed towards the central geometric axis X. With reference to the figure 1, in the belt structure building station 11, a dispensing station 34 also operates that is adapted to dispense semifinished products S. Preferably the dispensing station 34 comprises at least one feeder 35, for example in conveyor belt form, configured for conveying a semifinished product S up to the building drum 13 in order to determine the application around the deposition surface 14 while the building drum 13 rotates around the central geometric axis X.

The belt structure building station 11 is adapted to attain the belt structures 7 by a process for manufacturing stratified annular components in the manufacturing of tyres 2, according to the present invention. Such process is described hereinbelow with specific reference to the manufacturing of belt structures 7. Nevertheless, this can be conveniently employed, for example, for coupling the carcass sleeve 12 to the belt structure 7, or also for manufacturing, in addition or as alternative, different stratified annular components, such as for example carcass sleeves 12, tread bands 8, or other items, each comprising a plurality of annular layers that are radially superimposed on each other, with respect to the central geometric axis X and/or to the central geometric axis of the obtained tyre 2.

In the manufacturing of the belt structure 7, it is conveniently provided that one or more of said radially outer belt layers 7a, radially inner belt layer 7b and possible intermediate belt layers are attained by respective consecutive forming cycles, each starting from the respective semifinished product S. The semifinished product S is attained in strip form, having length substantially equal to the circumferential extension of the building drum 13, and can comprise the aforesaid reinforcement cords incorporated in a matrix made of green elastomeric material.

In each forming cycle, provision is made such that the semifinished product S coming from the feeder 35 is wound according to a substantially cylindrical shape around the first cylindrical deposition surface 14 of the building drum 13. In this step, the building drum 13 has the two half-drums 15 and the respective deposition sectors 15b adjacent to each other in the deposition condition, such that the annular opening 16 is substantially absent or has minimal axial size. The profiler drum 17 is arranged within the building drum 13 and in its first radially contracted operative condition.

With reference to figure 1, referred to an initial forming cycle aimed to attain the radially outer belt layer 7a, the annular retention member 23 is arranged in a wait position, axially offset with respect to the axial middle line plane M.

With respect to figure 2, following the pointing of the semifinished product S on the deposition surface 14 and of the rotation of the building drum 13 around the central geometric axis X, the semifinished product S is wound around the building drum 13, forming the radially outer belt layer 7a in cylindrical sleeve form coaxial with the central geometric axis X. In particular, the semifinished product S is deposited centrally between the two half-drums 15 at the axial middle line plane M. At the end of the winding of the semifinished product S, circumferentially terminal portions of the latter are brought to mate together along a circumferential direction of the building drum 13, mutually superimposed and joined together. With reference to figure 3, the profiler drum 17 can be slightly radially expanded (arrow Fl) up to bringing the profiler body 18 adjacent to the semifinished product S wound around the deposition surface 14.

By movement of the flanges 15a, for example, a mutual and symmetric moving apart of the half-drums 15 is then commanded along the central geometric axis X. In particular, with reference to figure 4, the half-drums 15 are partially removed from the semifinished product S (arrows F2), so as to generate or enlarge the annular opening 16 present between them. Simultaneously, the profiler drum 17 can be further radially expanded (arrow Fl).

With reference to figure 5, the profiler drum 17 is further radially expanded (arrow Fl) so as to engage the semifinished product S through the annular opening 16, by exerting a radial thrust action towards the exterior (according to the same arrow Fl) operating against a radially inner surface of the semifinished product S. In other words, the profiler drum 17 is expanded radially through the annular opening 16, so as to shape the semifinished product S according to a curved axial profile in accordance with the expansion surface 19.

The axial moving apart of the half-drums 15 and the radial expansion of the profiler drum 17 can occur according to subsequent mutually alternated steps, or simultaneously with a synchronized continuous movement.

The mutual moving apart of the half-drums 15 continues progressively during the expansion of the profiler drum 17 up to disengaging the semifinished product S simultaneously with a complete transfer of the latter on the profiler drum itself. In figure 6, the radial expansion of the semifinished product S is complete. The profiler drum 17 is in fact situated in the second operative condition, radially expanded. The half-drums 15 have in fact moved further axially apart (arrow F2), enlarging the annular opening 16 and being disengaged from the semifinished product S upon attainment of the open condition. The profiler body 18 has crossed the annular opening 16 and the semifinished product S completely abuts against the expansion surface 19.

With an axial movement along the linear guides 25 starting from the wait position, the annular retention member 23 is positioned coaxially in radial superimposition around the semifinished product S, preferably in axially centred position with respect to the latter in the axial middle line plane M. The axial movement of the annular retention member 23 can also be actuated after the winding of the semifinished product S around the deposition surface 14, before the start of the radial expansion of the profiler drum 17 or during the expansion thereof.

The execution of the above-described operations during the initial forming cycle determines, starting from the semifinished product S initially deposited in substantially cylindrical form on the deposition surface 14, the arrangement of a radially outer annular layer, i.e. the radially outer belt layer 7a, around the central geometric axis X and with toroidal shape having a concavity directed towards the central geometric axis X.

With reference to figure 7, the radially outer belt layer 7a is then engaged against the retention blocks 27 carried by the annular retention member 23, in a mutually adjacent position or at a predetermined mutual axial distance, in order to be retained thereby while the profiler drum 17 is radially contracted towards the first operative condition. For such purpose, provision can be made for the grip elements 26 to be arranged mutual approached in proximity to the axial middle line plane M and moved towards the respective first position in approaching the central geometric axis X (arrow F4), such that the grip surface 32 of each retention block 27 comes into contact with the radially outer surface of the radially outer belt layer 7a. Alternatively, the grip elements 26 can already be situated in the respective first position when the annular retention member 23 is axially positioned in centred position with respect to the semifinished product S, such that the radially outer belt layer 7a can reach the grip surfaces 32 at the end of the expansion of the profiling drum 17.

With reference to figure 8, the vacuum retention system is actuated such to exert a radial attraction action towards the exterior (arrows F5) operating on the radially outer belt layer 7a which is thus retained by the annular retention member 23. In the case of use of belts having metallic cords at the interior, the vacuum retention system could be substituted with an electromagnetic system. The profiler drum 17 is radially contract (arrow F6) by making the profiler body 18 completely re-enter into the zone inside the building drum 13. The two half-drums 15 are mutually approached in axial direction (arrows F7), reclosing the annular opening 16 and arranging the building drum 13 in the deposition condition, for manufacturing a new annular component, for example the radially inner belt layer 7b, with the execution of a new forming cycle. For such purpose, with reference to figure 9, the annular retention member 23 carrying the radially outer belt layer 7a is axially translated from the axial middle line plane M (arrow F8) in order to be re-situated in the wait position that is axially removed with respect to the building drum 13 and to the profiler drum 17. The annular retention member 23 in wait position frees the space surrounding the building drum 13, facilitating the access to the feeder 35 for the purpose of winding a new semifinished product S aimed for attaining a radially inner annular layer, i.e. the radially inner belt layer 7b or one of the aforesaid intermediate belt layers.

As is visible in figures 9 to 11, the forming cycle aimed for attaining the radially inner annular layer 7b can be carried out in a manner substantially analogous to the initial work cycle previously actuated for manufacturing the radially outer layer 7a. With reference to figure 12, with the completion of the expansion of the profiler drum 17 in the second operative condition, the radially inner belt layer 7b defined by the semifinished product S takes on toroidal shape having convexity directed away from the central geometric axis X.

After the annular retention member 23 has been situated in radial superimposition with respect to the semifinished product S previously wound around the building drum 13, the radially inner belt layer 7b is adapted to be applied against the radially inner surface of the radially outer belt layer 7a carried by the annular retention member 23.

As illustrated in figures 11 and 12, before the application of the radially inner belt layer 7b against the radially outer belt layer 7a, for example before radial expansion of the radially inner belt layer 7b starts, provision is made such that axially opposite end flaps of the radially outer belt layer 7a are mutually moved apart in axial sense (arrows F9), following an actuation of the axial movement actuators 30.

This action is better illustrated in figure 11a which underlines the deformations imposed on the radially outer belt layer 7a with respect to the radially inner belt layer 7b. The radially outer belt layer 7a, externally retained by the annular retention member 23, modifies its radial section by switching it from a first configuration, in which axially opposite end flaps 36 thereof are arranged at a first axial distance LI, to a second configuration, in which the axially opposite end flaps 36 of the radially outer belt layer 7a are arranged at a second axial distance L2 greater than the first axial distance LI.

Preferably, the second axial distance L2 is equal to or greater than a reference distance Lx detectable between axially opposite end flaps 37 of the radially inner belt layer 7b, when the latter is toroidally shaped due to the expansion of the profiler drum 17 in the second operative condition.

The first axial distance LI, the second axial distance L2 and said reference distance Lx are measurable parallel to the central geometric axis X. More precisely, the first axial distance LI and second axial distance L2 are detectable along a first axial direction dl traversing the axial middle line plane M, equidistant from the axially opposite end flaps 36 of the radially outer belt layer 7a.

The reference distance Lx is in turn detectable along a second axial direction d2 traversing the axial middle line plane M.

A first radial distance Drl detectable between a radially inner surface of the radially outer belt layer 7a and an intersection of the axial middle line plane M with the first axial direction dl, is equal to a second radial distance Dr2 detectable between a radially outer surface of the radially inner layer 7b, and an intersection of the axial middle line plane M with the second axial direction d2.

The radial section taken on by the radially outer belt layer 7a in the second configuration is adapted to receive the radially inner belt layer 7b in radial expansion (figure 11-12). Since the axially opposite end flaps 36 of the radially outer belt layer 7a are mutually moved away at the second axial distance L2, the initial contact between the radially inner belt layer 7b and the radially outer belt layer 7a can conveniently occur in proximity to the axial middle line plane M simultaneously with the attainment of the condition of maximum expansion of the profiler drum 17, in the absence of undesired mutual sliding between the radially inner belt layer 7b and the radially outer belt layer 7a.

As is visible in figure 12, at the end of the radial expansion of the radially inner belt layer 7b, a new activation of the axial movement actuators 30 (arrows F10) allows bringing back into the first configuration the radial section of the belt structure 7 being processed, reapproaching the axially opposite end flaps 36 of the radially outer belt layer 7a while the radially inner belt layer 7b is positioned against the radially outer belt layer 7a at the axial middle line plane M. Following such reapproaching the axially opposite end flaps 36 of the radially outer belt layer 7a come into contact with the radially inner belt layer 7b, consolidating the mutual coupling therewith. The stickiness of the green elastomeric material employed in manufacturing the semifinished products S allows a stable mutual adhesion of the radially inner belt layer 7b and of the radially outer belt layer 7a. With reference to figure 13, at the end of the radial expansion of the radially inner belt layer 7b with consequent formation of the belt structure 7 or other stratified annular component, the annular retention member 23 can be radially expanded by moving the grip elements 26 towards the second position in which they are moved away from the central geometric axis X (arrow Fll). The vacuum retention system can in turn be deactivated by cancelling the radial traction action, so as to release the belt structure 7 on the profiler drum 17.

The annular retention member 23 is adapted to be axially translated with respect to the profiler drum 17 in order to be brought back into the wait position of figure 1. The half-drums 15 are in turn mutually and axially moved apart (arrows F12) and are arranged in the open condition, at a mutual distance such to allow the complete access to the zone inside the building drum 13.

In this circumstance, the profiler drum 17 is adapted to be picked up from the belt structure building station 11 in order to be transferred to the assembly station 38, or other subsequent station provided in the processing process, together with the belt structure 7 engaged thereon, in order to continue the building of the tyre 2.

The assembly station 38 can be conveniently associated with a grip unit 39 arranged to receive the belt structure 7 carried by the profiler drum 17, in order to allow the subsequent coupling with the carcass sleeve 12. The grip unit 39, which can be attained in a manner analogous to the annular retention member 23 and therefore is only schematically illustrated, can have annular shape and comprise radially movable sectors, possibly operating by vacuum, by suction and/or suction systems. Preferably the grip unit 39 is movable in entering into and exiting from the assembly station 38, e.g. on movement axes 40 parallel and perpendicular to a central axis Y of the assembly station 38. With 41, a transfer device is indicated that is operating between the belt structure building station 11 and the grip unit 39 that equips the assembly station 38. The transfer device 41 can be made by a suitable robot 42 adapted to retain the profiler drum 17 in order to pick it up from the belt structure building station 11 and transfer it towards the assembly station 38, inserting it within the grip unit 39.

The belt structure 7 is then adapted to be transferred by the profiler drum 17 to the grip unit 39, possibly with a radial contraction movement of the sectors of the latter and a subsequent radial contraction of the profiler drum 17, in order to be brought back into the assembly station 38 together with the grip unit 39 moved along the movement axes 40.

Meanwhile, the carcass sleeve 12 attained - for example - in the carcass structure building station 10 is transferred into the assembly station 38 by means of loading devices 43, and positioned coaxial with the central axis Y.

With a movement of the grip unit 39 along the central axis Y, the belt structure 7 is situated in axially centred position around the carcass sleeve 12.

The assembly station 38, not described in detail since it can be obtained in a known manner, for example according to that described in the aforesaid patent US 10,611,110 B2, is then adapted to shape the carcass sleeve 12, causing a radial expansion thereof according to a toroidal shape, in order to couple it to the belt structure 7 retained by the grip unit 39 and thus completing the building of the tyre 2, for example by application (in a known and non-illustrated manner) of the tread band 8 and the possible execution of further operations, in the same assembly station 38 or in another subsequent nonillustrated station.

The profiler drum 17 is in turn adapted to be brought back into the belt structure building station 11, in order to start the manufacture of a new belt structure 7 or another stratified annular component with a mutual approach of the half-drums 15 in the position of figure 1.

Alternatively, the profiler drum 17 moved away from the shaping station 37 can be situated in a waiting store (not illustrated), and the belt structure building station 11 can be equipped with a further profiler drum 17, having geometric characteristics different from that used before, in order to manufacture a belt structure 7 of a tyre having different geometric and/or size specifications. The axial and radial mobility of the retention blocks 27 facilitates the adaptability of the annular retention member 23 to profiler drums 17 of different sizes and configurations, from time to time employable as a function of the production requirements.

In a further non-illustrated embodiment, provision can be made such that the annular retention member 23 is movable from the belt structure building station 11 to the assembly station 38. In this case, at the end of the radial expansion of the radially inner belt layer 7b, the profiler drum 17 can be contracted towards the first operative condition, in order to release the belt structure 7 retained by the annular retention member 23 which maintains the first position radially contracted. The retention ring is then adapted to transfer the belt structure 7 into the assembly station 38 and to retain it up to the completed coupling with the carcass sleeve 12 shaped according to a toroidal configuration, while the profiling drum 17 remains in the belt structure building station 11 in order to start, for example, the manufacture of a new belt structure. The axial mobility of the retention blocks 27 offers the possibility to facilitate the coupling of the carcass sleeve 12 with the belt structure 7 in the absence of sliding. The axially opposite end flaps 36 and/or 37 of the belt layer or layers 7a and/or 7b are indeed adapted to be mutually moved apart at the second axial distance L2 in order to facilitate the expansion of the carcass sleeve 12 in the absence of sliding up to coming into contact with the belt structure 7.

Claims

1. Method for manufacturing stratified annular components in the manufacturing of tyres for vehicles comprising: arranging, around a central geometric axis (X), a radially outer annular layer (7a) with toroidal shape having a concavity directed towards the central geometric axis (X); moving, mutually apart, axially opposite end flaps (26) of the radially outer layer (7a), before internally applying a subsequent annular layer to said radially outer annular layer (7a).

2. Method according to claim 1, wherein said subsequent annular layer is a radially inner annular layer (7b) with toroidal shape having a convexity directed away from the central geometric axis (X).

3. Method according to claim 2, wherein an initial contact between the radially inner annular layer (7b) and the radially outer annular layer (7a) occurs in proximity to an axial middle line plane (M) equidistant from said axially opposite end flaps (36) of the radially outer layer (7a).

4. Method according to claim 2 or 3, wherein the axially opposite end flaps (36) of the radially outer layer (7a) are mutually moved apart up to reaching a mutual second axial distance (L2) not less than a reference distance (Lx) detectable between axially opposite end flaps (37) of the radially inner annular layer (7b).

5. Method according to claim 4, wherein: said second axial distance (L2) is detectable along a first axial direction (dl) traversing an axial middle line plane (M) equidistant from the axially opposite end flaps (36) of the radially outer annular layer (7a), said reference distance (Lx) is detectable along a second axial direction (d2) traversing said axial middle line plane (M), wherein a first radial distance (Drl) detectable between a radially inner surface of the radially outer annular layer (7a) and an intersection of the axial middle line plane (M) with the first axial direction (dl), is equal to a second radial distance (Dr2) detectable between a radially outer surface of the radially outer annular layer (7a), and an intersection of the axial middle line plane (M) with the second axial direction (d2).

6. Method according to one or more of claims 2 to 5, also comprising the action of reapproaching the axially opposite end flaps (36) of the radially outer annular layer (7a) at the end of the application of the radially inner annular layer (7b).

7. Method according to claim 6, wherein the reapproaching of the axially opposite end flaps (36) of the radially outer annular layer (7a) is executed while the radially inner annular layer (7b) is positioned against the radially outer annular layer (7a) at least at an axial middle line plane (M) substantially equidistant from the end flaps themselves.

8. Method according to claim 6 or 7, wherein following the reapproaching, the axially opposite end flaps (36) of the radially outer annular layer (7a) come into contact with the radially inner annular layer (7b).

9. Method according to one or more of the preceding claims, wherein arranging the radially outer annular layer (7a) comprises: depositing the radially outer annular layer (7a) according to a substantially cylindrical shape around the central geometric axis (X); expanding, within the radially outer annular layer (7a), a profiler drum (17) having an expansion surface (19) that is radially outer and axially convex, in order to toroidally shape the radially outer annular layer (7a).

10. Method according to one or more of claims 2 to 9, wherein applying the radially inner annular layer (7b) comprises: depositing the radially inner annular layer (7b) according to a substantially cylindrical shape around the central geometric axis (X); expanding, within the radially inner annular layer (7b), a profiler drum (17) having an expansion surface (19) that is radially outer and axially convex, in order to toroidally shape the radially inner annular layer (7b).

11. Method according to claim 10, wherein an initial contact between the radially inner annular layer (7b) and the radially outer annular layer (7a) occurs simultaneously with the attainment of a condition of maximum expansion of said profiler drum (17).

12. Method according to one or more of claims 2 to 11, also comprising the action of retaining the radially outer annular layer (7a) at a radially outer surface thereof during the application of the radially inner annular layer (7b).

13. Apparatus for manufacturing stratified annular components in the building of tyres for vehicles, comprising: an annular retention member (23) with toroidal shape having a concavity directed towards a central geometric axis (X); application devices comprising a profiler drum (17) with toroidal shape having a convexity directed away from the central geometric axis (X); wherein the annular retention member (23) comprises two axially opposite retention annular portions (27a), each directed towards the central geometric axis (X); wherein the retention annular portions (27a) are movable with respect to each other.

14. Apparatus according to claim 13, wherein the retention annular portions (27a) are axially movable on command of one or more axial movement actuators (30).

15. Apparatus according to claim 13 or 14, wherein each of the retention annular portions (27a) has suction ducts (33) leading to respective openings that are distributed and directed towards the central geometric axis (X).

16. Apparatus according to one or more of claims 13 to 15, wherein the annular retention member (23) comprises a plurality of grip elements (26) that are circumferentially distributed around the central geometric axis (X).

17. Apparatus according to claim 16, wherein said grip elements (26) are radially movable with respect to the central geometric axis (X).

18. Apparatus according to claim 16 or 17, wherein each of said grip elements (26) comprises two retention blocks (27) that are axially side-by-side each other, each belonging to one of said retention annular portions (27a).

19. Apparatus according to claim 18, wherein each of said grip elements (26) comprises a support element (28) carrying said retention blocks (27), axially slidable with respect to the respective support element (28).

20. Apparatus according to claim 18 or 19, wherein the retention blocks (27) belonging to each grip element (26) are mutually interconnected by a threaded bar (29) actuatable in rotation by said axial movement actuator (30).

21. Apparatus according to one or more of claims 13 to 20, wherein the annular retention member (23) comprises a support structure (24) arranged circumferentially around the central geometric axis (X).

22. Apparatus according to claim 21, wherein the support structure (24) is movable parallel to the central geometric axis (X).

23. Apparatus according to one or more of claims 13 to 22, wherein said profiler drum (17) can be positioned coaxial to the central geometric axis (X) in axially centred position with respect to the annular retention member (23), and switchable from a radially contracted condition to a radially expanded condition.

24. Apparatus according to one or more of claims 13 to 23, wherein said application devices also comprise a building drum (13), coaxial with the central geometric axis (X) in axially centred position with respect to the annular retention member (23), and comprising two half-drums (15) that are axially approachable in order to define a substantially cylindrical deposition surface (14).

25. Apparatus according to one or more of claims 13 to 24, wherein said annular retention member (23) is configured for retaining, around said central geometric axis (X), a radially outer annular layer (7a).

26. Apparatus according to claim 25, wherein said profiler drum (17) is configured for applying, internally against the radially outer annular layer (7a), a radially inner annular layer (7b).

27. Apparatus according to claim 25 or 26, wherein said two retention annular portions (27a) are configured for operating against the radially outer annular layer (7a).

28. Apparatus according to one or more of claims 13 to 27, wherein said retention annular portions (27a) are axially movable with respect to each other.

29. Apparatus according to one or more of the claims 25 to 28 when dependent on clam 23, wherein said profiler drum (17) is switchable from said radially contracted condition to said radially expanded condition in order to carry the radially outer annular layer (7a) against the retention annular portions (27a).