Shaping drum for producing tyres for vehicle wheels and method for changing the geometry of a shaping drum for producing tyres for vehicle wheels

Abstract

A forming drum (1) comprises: a plurality of sectors (5, 7) for defining at least one laying surface (3, 4, 6); a central body (2) connected to the plurality of sectors (5, 7) to set the sectors (5, 7) in rotation; coupling members (17) operating between each sector (5, 7) and the central body (2), wherein each coupling member (17) comprises a first element (18) movably connected to the central body (2) or the sector (5, 7) and a second element (18) movably connected to the other of the central body (2) and the sector (5, 7). Two elements (19), wherein the first element (18) is configured to engage a first portion (25) of the second element (19) and radially retain the sectors (5, 7) to the center body (2) and to disengage from the first portion (25) of the second element (19) and radially release the sectors (5, 7) from the center body (2), wherein the second element (19) is configured to move between a state in which the second portion (26) of the second element (19) locks the first element (18) and a state in which the second portion (26) is axially spaced apart from the first element (18).

Description

Technical Field

[0001] The invention relates to a shaping drum for producing tyres for vehicle wheels and to a method for changing the geometry of a shaping drum for producing tyres for vehicle wheels. Background Art

[0002] A tyre for vehicle wheels generally comprises a carcass structure, a crown structure arranged in a radially outer position with respect to the carcass structure and a pair of sidewalls representing the axially outer surface of the tyre with respect to a median plane perpendicular to the axis of rotation of said tyre.

[0003] The carcass structure comprises at least one carcass ply formed of reinforcing cords incorporated in a matrix of elastomeric material. The carcass ply has opposite end edges respectively engaged with annular anchoring structures. The annular anchoring structures are arranged in a tire region generally identified by the name "bead" and are generally each formed by a substantially circumferential annular insert or "bead core" on which, in a radially external position, at least one filling insert is applied which tapers radially away from the axis of rotation.

[0004] At the beads, specific reinforcement structures may be provided which improve the torque transmission to the tire.

[0005] In the case of a "tubeless" tire (i.e. without an air chamber), a layer of elastomeric material, usually called a "liner", may also be provided in a radially inner position relative to the carcass structure to provide the necessary impermeability to inflation air of the tire. Typically, the liner extends from one bead to the other.

[0006] The crown structure comprises a belt structure and a tread band made of elastomeric material in a radially outer position with respect to the belt structure.

[0007] The belt structure comprises a belt layer or a plurality of belt layers arranged radially superimposed on each other, said belt layers having textile or metallic reinforcing cords having an orientation substantially parallel to the circumferential extension direction of the tyre (zero degree layer) and / or having a crossed orientation.

[0008] Between the carcass structure and the belt structure there may be arranged a layer of elastomeric material, called "lower belt", the function of which is to make the radially outer surface of the carcass structure as flat as possible for the subsequent application of the belt structure.

[0009] Longitudinal and transverse grooves are typically moulded on the tread band, arranged so as to define the desired tread pattern.Between the tread band and the belt structure there may be interposed a so-called "sublayer" of elastomeric material, the properties of which are suitable for obtaining a stable bonding of the belt structure to the tread band itself.

[0010] The sidewalls are made of elastomeric material and represent an axially external surface relative to the annular anchoring structures, relative to the carcass ply(s), relative to the belt(s) and possibly relative to at least one portion of the tread band. For example, each sidewall extends from one of the lateral edges of the tread band as far as the respective annular anchoring structure to the bead.

[0011] The term "elastomeric material" refers to a composition comprising at least one elastomeric polymer and at least one reinforcing filler. Such a composition may also contain additives, such as a crosslinking agent and / or a plasticizer. Due to the presence of the crosslinking agent, such a material may be crosslinked by heating to form a final product.

[0012] The term "green tire" refers to a tire obtained from the building process but not yet molded and cured.

[0013] The term "finished tire" refers to a tire obtained by molding and vulcanizing a green tire.

[0014] The term "tire" refers to a finished or green tire.

[0015] The terms "axial", "axially", "radial", "radially", "circumferentially" and "circumferentially" are used with reference to a forming drum used in the production process of tyres.

[0016] In particular, the terms "axial" and "axially" refer to references / quantities arranged / measured or extending in a direction substantially parallel to the geometrical rotation axis of the forming drum.

[0017] The terms "radial" and "radially" refer to references / quantities arranged / measured or extending in a direction substantially perpendicular to the geometrical axis of rotation of the forming drum and lying in a plane including said geometrical axis of rotation.

[0018] The terms "radially inner / outer" refer to a position which is respectively closer to or further away from the above-mentioned geometrical axis of rotation of the forming drum.

[0019] The terms "axially inner / outer" refer to a position respectively closer to or further away from a mid-plane perpendicular to the geometrical rotation axis of the forming drum.

[0020] The terms "circumferentially" and "circumferentially" refer to references / measurements arranged / measured or extending along a circumference extending around the geometric axis of rotation of the forming drum.

[0021] The term "structural component" of a tyre means any part thereof or a portion thereof capable of performing its function. Examples of structural components of a tyre are the following: carcass structure, crown structure or parts thereof, such as liner, underliner, wear-resistant insert, bead core, filling insert in the bead region (and thus the annular anchoring structure defined by the bead core and the respective filling insert), carcass ply (or plies), belt (or plies), belt underlayer, bottom layer of the tread band, sidewalls, sidewall inserts, tread band, textile or metal reinforcements, reinforcing elements made of elastomeric material, etc. or parts thereof.

[0022] The term "tyre in process" means a tyre that is in any step of the relevant production process starting from the construction of at least one of the structural components constituting the carcass structure and / or the crown structure until the finished tyre is obtained. For example, a tyre in process is a tyre that enters / leaves a workstation dedicated to applying annular anchoring structures on the opposite end edges of a carcass ply (or plies) previously laid on a forming drum and folding these end edges around the aforementioned annular anchoring structures.

[0023] The term "machine downtime" refers to the period of time during which a tire production facility is not operating due to format change operations ("setup") for a production batch.

[0024] The production cycle of a tire provides that, after a green tire building process of building and assembling the various structural components of the tire itself, the green tire is transferred to a molding and vulcanization line where a molding and vulcanization process is carried out that is suitable for defining the structure of the finished tire according to the desired geometry and tread pattern.

[0025] The building of the tyre structural components and their subsequent assembly is carried out on suitable forming drums. For example, the carcass structure can be built on a first forming drum, called the first-stage drum, and the crown structure can be built on a second forming drum, called the auxiliary drum or the second-stage drum. The assembly of the carcass structure with the crown structure can be carried out on the first forming drum, in which case the first-stage drum takes the name of a "single-stage" drum, or the assembly of the carcass structure with the crown structure can be carried out on different forming drums, called forming drums.

[0026] WO2009 / 058296 discloses a forming drum comprising a plurality of modules which are releasably mounted around the drum to define a cylindrical working surface. A first and a second locking stop are mounted at opposite ends of the modules and a corresponding receiver is mounted on a mounting ring of the drum. The locking stop comprises a protrusion intended to be inserted into a groove of the receiver. Each locking stop comprises a housing which contains a rotating rod which is rotationally urged by a spring to engage a pin arranged in the receiver. When the protrusion of the stop is fully inserted into the groove of the receiver, the housing of the locking stop is automatically fixed to the pin of the receiver. In order to disengage the locking stop from the receiver, a release pin is mounted in the housing of the stop to engage and rotate the rotating rod and provide a force sufficient to disengage the rotating rod from the pin for a user application.

[0027] WO2012 / 056409 of the same applicant discloses a forming drum comprising a plurality of circumferential sectors arranged in series around a central body. A snap-fit ​​device is provided to associate and remove the circumferential sectors with the central body of the drum. The snap-fit ​​device comprises a fixed fastening element associated with the sector, which extends in a radial direction from the radial inner surface of the sector and is adapted to be snugly received in a radial opening formed in an arm of the central body. A movable fastening element axially arranged in the arm of the central body faces the radial opening and is always pushed into the radial opening by a spring. The fixed fastening element comprises at least one inclined surface adapted to interact with the movable fastening element to move it from an active position to a passive position and cause its engagement in the seat of the fixed fastening element, thereby activating the snap-fit ​​of the fastening device. A release element can be inserted in the sliding seat of the fixed fastening element to access the movable fastening element and bring it back to the passive position, thereby eliminating the constraint with the fixed fastening element.

[0028] The applicant has observed that, according to the assembly diameter of the finished tire, the diameter of the laying surface of the forming drum required to make it is different. In particular, the applicant has observed that as the matching diameter increases / decreases, the diameter of the laying surface of the forming drum required to make this tire model increases / decreases.

[0029] The Applicant has felt the need to manage the forming drums without having to provide specific stores of large dimensions required to store drums with laying surfaces of different diameters, while still ensuring the possibility of manufacturing tyres with different fitting diameters.

[0030] The Applicant has observed that the forming drum described in document WO 2012 / 056409 allows replacing the sectors constituting the laying surface of the forming drum to vary the diameter of the laying surface, thus allowing to provide laying surfaces of different diameters using the same forming drum with different sets of circular sectors.

[0031] The Applicant has noted that the snap-fit ​​engagement device described in document WO 2012 / 056409 allows to easily activate and deactivate the constraint between the curved sectors of the central body and the forming drum.

[0032] The Applicant has indeed demonstrated that, during the step of activating the constraint between the curved sectors and the central body of the forming drum, the fixed fastening elements provided on the radially inner surface of the curved sectors are inserted with a precise shape coupling in radial openings provided on the arms of the central body of the forming drum, said radial openings serving as insertion guides for the fixed fastening elements. The fixed fastening elements activate the movable fastening elements held by them in the radial direction. Summary of the invention

[0033] However, the Applicant has observed that, particularly with regard to modern highly automated building lines, it is very advantageous to carry out sector changes of the forming drum as quickly as possible to reduce machine downtimes (and therefore "line downtimes"), but without giving up the ease of carrying out sector changes.

[0034] The Applicant thus observes that the modification of a sector provides for the removal of a sector (after it has been released from the central body of the forming drum) away from a corresponding seat provided in the central body of the forming drum. Similarly, during the connection of a new sector, it is provided for the positioning of the new sector (before it is constrained to the central body of the forming drum) so as to insert it into a seat provided in the central body of the forming drum.

[0035] The Applicant has also observed that the speed and ease of sector change vary as a function of both the activation and deactivation of the constraints between the sectors and the central body of the forming drum and of the removal and positioning operations of the sectors.

[0036] The Applicant has realized that the absence of a forced alignment and a precise shape connection between the sectors and the center body facilitates the removal of sectors from the center body and in particular the positioning of new sectors on the center body. In fact, in the absence of a forced alignment and a precise shape connection between the sectors and the center body, the positioning of the new sectors requires a precise orientation of the new sectors relative to the center body and the movement of the new sectors towards the center body without losing the precise orientation found, while the removal of the sectors requires moving the sectors away from the center body while maintaining the precise alignment requirements of the shape connection.

[0037] The applicant has therefore discovered that by providing a gap between the sectors of the drum and the center body when the constraint between the sectors and the center body is deactivated, the sectors can be quickly and easily removed from the center body and positioned on the center body, since the said gap can be used to compensate for small misalignments that may occur during the steps of insertion and removal of the sectors from the center body.

[0038] The invention therefore relates in a first aspect thereof to a forming drum for producing tyres for vehicle wheels.

[0039] Preferably, there is provided a central shaft concentric with the geometrical axis of rotation of the forming drum and a plurality of sectors arranged circumferentially around the central shaft to define at least one laying surface.

[0040] Preferably, a central body is provided which is connected to the central axis and to the plurality of sectors so as to arrange the sectors to rotate about the central axis.

[0041] Preferably, there is provided a coupling member operative between each of the plurality of sectors and the central body, the coupling member being configured to retain and release each sector from the central body.

[0042] Preferably, each coupling member comprises a first element movably connected to one of the central body and the sectors and a second element movably connected to the other of the central body and the sectors, said second element comprising a first portion and a second portion.

[0043] Preferably, the first element is configured to move between a retaining condition in which it engages the first portion of the second element and radially retains the sector to the central body, and a releasing condition in which it disengages from the first portion of the second element and radially releases the sector from the central body.

[0044] Preferably, the second element is configured to move between a holding state, in which the second part locks the first element in the respective holding state, and a release state, in which the second part is axially spaced from the first element and allows the first element to reach the respective release state.

[0045] The Applicant considers that the forming drum according to the invention makes it possible to accelerate and facilitate the change of sectors. In fact, the first and second elements of the coupling member lock together the sectors and the central body of the forming drum when they are in their respective holding conditions. When the second element is in the released condition, the sectors and the central body are not axially locked together, allowing the first element to move in the released condition (thus radially releasing the sectors from the central body) and forming an axial gap between the sectors and the central body, which allows relative sliding between the sectors and the central body even in the face of small misalignments between the sectors and the central body.

[0046] In a second aspect of the invention, the invention relates to a method for changing the geometry of a forming drum for producing tyres for vehicle wheels.

[0047] It is preferably provided that the paving surface is arranged by sectors which are arranged circumferentially around a central axis and which are removably coupled to a central body.

[0048] Preferably, it is provided that a coupling member is arranged for each sector, said coupling member comprising a first element movably connected to one of the central body and the sector and a second element movably connected to the other of the central body and the sector, said second element comprising a first part and a second part.

[0049] Preferably, provision is made for the paving surface to be changed by removing sectors from the central body and inserting new sectors on the central body.

[0050] Preferably, removing the sectors from the center body comprises, for each sector, moving the second portion of the second element axially away from the first element, disengaging the first element from the first portion of the second element, and spacing the sectors apart from the center body.

[0051] Preferably, inserting new sectors on the central body comprises, for each new sector, moving the new sector towards the central body, moving the first element into engagement with the first portion of the second element, and moving the second portion of the second element axially towards the first element until the first element is locked.

[0052] The applicant believes that in this way, at each replacement, the sector to be removed can be moved away from the central body, the second portion of the second element not blocking the axial movement of the sector and the first element not blocking the radial movement of the sector. The new sector to be inserted can be moved towards the central body and positioned on the central body, the second portion of the second element not blocking the axial movement of the new sector and the first element not blocking the radial movement of the sector. This makes it possible to form both axial and radial clearances during the insertion / removal of the sector, thus facilitating and accelerating the sector change operation. For example, in the case where the sector moves radially away from the central body and the new sector moves radially towards the central body, the axial clearance allows relative sliding between the sector and the central body, even in the face of a small misalignment in the axial direction between the sector and the central body. In the case where the sector moves axially away from the central body and the new sector moves axially towards the central body, the radial clearance allows relative sliding between the sector and the central body, even in the face of a small misalignment in the radial direction between the sector and the central body.

[0053] In at least one of the above aspects, the present invention may have at least one of the preferred features described below.

[0054] Preferably, the first element moves in a radial plane between the retaining state and the release state and between the release state and the retaining state to engage and disengage the first portion of the second element.

[0055] In this way, the first element moves in a plane (radial plane) which is substantially perpendicular with respect to the (axial) direction in which the second element moves.

[0056] Preferably, the first element rotates around the axial direction to switch from the holding state to the releasing state and from the releasing state to the holding state.

[0057] Preferably, disengaging the first element from the first part of the second element includes rotating the first element around an axial direction from a corresponding retaining state of the first element, in which the first element engages the first part of the second element and radially retains the sector to the center body, to a corresponding release state, in which the first element disengages from the first part of the second element and radially releases the sector from the center body.

[0058] Preferably, the first portion of the second element is configured to axially move the second portion of the second element and to move the second portion of the second element between the retaining state and the releasing state.

[0059] Preferably, moving the second part of the second element axially away from the first element comprises moving the second element axially from a corresponding retaining state to a corresponding release state, in which the second part locks the first element in the corresponding retaining state, and in which the second part is axially spaced from the first element and allows the first element to reach the corresponding release state.

[0060] Preferably, engaging the first element with the first part of the second element comprises rotating the first element around an axial direction from a corresponding release state in which the first element is disengaged from the first part of the second element to a corresponding retention state in which the first element engages the first part of the second element and radially retains the new sector to the center body.

[0061] Preferably, moving the second portion of the second element axially toward the first element until the first element is locked comprises moving the second element axially from a respective release state to a respective retaining state, wherein the second portion of the second element is axially spaced from the first element, and wherein the second portion of the second element locks the first element in the respective retaining state.

[0062] Preferably, the first element includes a first portion rotatably connected to the center body and one of the sectors and a second portion located distal to the first portion, wherein the second portion is configured to move in a circular path and intercept the first portion of the second element during transition from the release state to the retention state.

[0063] Preferably, the first portion of the second element comprises a pin extending in the axial direction, wherein the second portion of the second element comprises a head arranged at an end of the pin; the radial dimension of the head is greater than the radial dimension of the pin.

[0064] Preferably, the second portion of the first element comprises a slot having an arcuate shape and opening at a first end, the slot being configured to receive a pin of the second element when the first element is in the retaining state.

[0065] Preferably, when the first element and the second element are in their respective holding states, the head of the second element contacts the edge of the slot.

[0066] Preferably, disengaging the first element from the first portion of the second element comprises arranging the first element to have a slot having an arcuate shape and opening at a first end, rotating the first element such that the first portion of the second element comes out of the slot.

[0067] Preferably, engaging the first element with the first portion of the second element comprises arranging the first element to have a slot having an arcuate shape and opening at a first end, rotating the first element such that the first portion of the second element is inserted into the slot.

[0068] Preferably, the operation of rotating the first element to make the slot come out of the first portion of the second element is performed in an angular direction opposite to the operation of rotating the first element to insert the first portion of the second element inside the slot.

[0069] Preferably, axially moving the second portion of the second element towards the first element comprises arranging the second portion of the second element to have a head and axially abutting the head against the first element.

[0070] Preferably, moving the second portion of the second element axially away from the first element comprises arranging the first portion of the second element to have a pin with a threaded outer surface and partially unscrewing the pin from the seat.

[0071] Preferably, the first element is movably connected to the sectors and the second element is movably connected to the central body.

[0072] Preferably, each sector comprises at least one spacer extending away from the radially inner surface of the sector; the first element of the coupling member is movably coupled to the at least one spacer of each sector.

[0073] Preferably, the spacer comprises an abutment surface distal to the radially inner surface of the sector, the abutment surface being configured to contact the abutment surface of the central body.

[0074] Preferably, the spacer comprises two shoulders and a connecting surface arranged between the two shoulders; the connecting surface being configured to receive a first portion of the second element of the coupling member between the two shoulders.

[0075] Preferably, when the first and second elements of the coupling member are in their respective retained states, the second portion of the second element presses the first element axially against the two shoulders of the spacer.

[0076] Preferably, moving the new sector towards the center body comprises arranging a spacer on the radially inner surface of the new sector, providing the spacer with at least one abutment surface distal to the radially inner surface of the sector, and bringing the abutment surface of the spacer into contact with the abutment surface of the center body.

[0077] Preferably, bringing the abutment surface of the spacer into contact with the abutment surface of the central body comprises providing the spacer with two shoulders and a connection surface and receiving the first portion of the second element of the coupling member between the two shoulders at the connection surface.

[0078] Preferably, moving the sector away from the central body comprises arranging a spacer on the radially inner surface of the sector, providing the spacer with at least one abutment surface distal to the radially inner surface of the sector, and moving the abutment surface of the spacer away from the abutment surface of the central body.

[0079] Preferably, moving the abutment surface of the spacer away from the abutment surface of the central body comprises providing the spacer with two shoulders and a connecting surface and withdrawing the first part of the second element of the coupling member from the two shoulders at the connecting surface.

[0080] Preferably, the first element is arranged axially between the second portion of the second element and the spacer.

[0081] Preferably, the first portion of the second element comprises a threaded outer surface and is screwed into a seat formed in the central body with an insertion depth; the switching of the second element from the release state to the retention state is performed by increasing the insertion depth of the first portion of the second element in the seat of the central body.

[0082] Preferably, the second portion of the second element is configured to control the insertion depth of the first portion of the second element in the seat formed in the central body. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Further features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the accompanying drawings.

[0084] In these figures:

[0085] - Figure 1 is a schematic perspective view of a forming drum for tyres for vehicle wheels according to the present invention;

[0086] - Figure 2 yes Figure 1 a schematic side view of the drum of , with some parts removed to better highlight other parts;

[0087] - Figure 3 yes Figure 1 a schematic perspective view of some parts of the drum;

[0088] - Figure 4 yes Figure 3 a schematic front view of a portion of a drum;

[0089] - Figure 5 and Figure 6 In two different operating states Figure 4 Details;

[0090] - Figure 7 yes Figure 1 a schematic perspective view of some parts of the drum;

[0091] - Figure 8 yes Figure 7 Schematic front views of parts of the drum in different operating states; and

[0092] - Fig. 9 yes Figure 8 A perspective view of a portion of a drum is shown in FIG. DETAILED DESCRIPTION

[0093] exist Figure 1-9 In the drawings, reference numeral 1 denotes as a whole a shaping drum for tyres for vehicle wheels according to the present invention.

[0094] The drum 1 comprises a central body 2 to which the paving surface is radially connected. A central shaft 2a having an axial extension is passed through a geometric axis X about which the drum 1 rotates. The central body 2 is connected to the central shaft 2a to set the paving surface in rotation. The paving surface comprises a plurality of sectors arranged radially around the central body 2.

[0095] In a preferred embodiment of the invention, the laying surface comprises two lateral laying surfaces 3, 4, which are substantially cylindrical, axially opposite each other and arranged in rotation by a central axis 2a.

[0096] The lateral paving surfaces 3 , 4 each comprise a respective sector 5 .

[0097] At least in the laid state of the drum 1 , the radially outer surfaces 5a of the sectors 5 are arranged with respect to one another so as to create a substantially continuous surface.

[0098] In a preferred embodiment of the present invention, the lateral laying surfaces 3, 4 are arranged relative to the central axis 2a in the laying state (in Figure 1 and 2In particular, in the laying state, the sectors 5 are radially spaced apart from the central axis 2a, whereas in the overhaul state, the sectors 5 are radially moved towards the central axis 2a. In the overhaul state, the sectors 5 are not circumferentially aligned with each other, but rather a discontinuity is created and no continuous radial outer surface is formed for the drum 1. The overhaul state may be performed, for example, to remove a carcass structure, a belt structure or a tyre formed on the forming drum 1.

[0099] In a preferred embodiment of the present invention, the paving surface further comprises a central paving surface 6 arranged axially between the two lateral paving surfaces 3, 4. Figure 1 and 2 The central laying surface 6 is also connected to the central body 2.

[0100] The central laying surface 6 comprises respective sectors 7. At least in the laying state of the drum 1, the radially outer surfaces 7a of the sectors 7 are arranged with respect to each other so as to create a substantially continuous surface. The central laying surface 6 is arranged relative to the central axis 2a in the laying state (in Figure 1 and 2 In particular, in the laying state, the sectors 7 are radially spaced from the central axis 2a, while in the maintenance state, the sectors 7 are radially moved toward the central axis 2a. In the laying state, the central laying surface 6 and the two lateral laying surfaces 3, 4 are continuous and substantially aligned with each other.

[0101] The sectors 7 of the central paved surface 6 are axially connected in a sliding manner to the sectors 5 of the lateral paved surfaces 3, 4. The sectors 7 of the central paved surface 6 are rigidly radially connected to the sectors 5 of the lateral paved surfaces 3, 4, so that radial movements of the sectors 7 of the central paved surface 6 cause the same radial movements of the sectors 5 of the lateral paved surfaces 3, 4, and so that radial movements of the sectors 5 of the lateral paved surfaces 3, 4 cause the same radial movements of the sectors 7 of the central paved surface 6. The sectors 7 of the central paved surface 6 are rotatably connected to the sectors 5 of the lateral paved surfaces 3, 4, so that rotations of the sectors 7 of the central paved surface 6 about the geometric axis X cause the same rotations of the sectors 5 of the lateral paved surfaces 3, 4 about the geometric axis X, and so that rotations of the sectors 5 of the lateral paved surfaces 3, 4 about the geometric axis X cause the same rotations of the sectors 7 of the central paved surface 6 about the geometric axis X.

[0102] like Figure 1 As shown, the auxiliary support element 8 is arranged in an axially outer position relative to the two lateral laying surfaces 3, 4. The auxiliary support element 8 is preferably annular and comprises a radially outer surface 8a which is substantially aligned with the lateral laying surfaces 3, 4 when in the laying state. Each auxiliary support element 8 is axially constrained to the corresponding lateral laying surface 3, 4 in a removable manner.

[0103] In order to allow the lateral paving surfaces 3, 4 and the central paving surface 6 to contract and expand radially, the central body 2 comprises expansion links 9 (at Figure 3 The expansion link is configured to move the central sector 7 in the radial direction. The radial movement of the sector 7 of the central paving surface 6 is transmitted to the sectors 5 of the lateral paving surfaces 3,4.

[0104] In the preferred embodiment of the present invention, the expansion link 9 includes an operating shaft 10 rotatably mounted on the central shaft 2a (at Figure 3 ). The steering shaft 10 is fixedly connected to a steering ring 11 which is rotatable relative to the central axis 2a and is axially positioned at the sector 7 of the central paving surface 6. The sector 7 is connected to the steering ring 11 by a connecting rod 12, one end of which is hinged to the steering ring 11 and the other end of which is hinged to a support 2d for the sector 7 of the central paving surface 6 (a support of the central body 2). Each sector 5 of the lateral paving surfaces 3, 4 is connected to a first end of a telescopic support 13 by a support 2c of the central body 2. The second end of the telescopic support 13 is connected to a crown 14 (see FIG. 1 ) which is slidably mounted on the steering shaft 10. Figure 3 ). By rotating the operating shaft 10 relative to the central axis 2a from the maintenance state in a first angular direction, radial expansion of the sectors 7 of the central paving surface 6 is performed until the paving state is reached. The radial movement of the sectors 7 of the central paving surface 6 also pulls the sectors 5 of the lateral paving surfaces 3, 4 into the paving state. By rotating the operating shaft 10 relative to the central axis 2a from the paving state in a second angular direction, radial contraction of the sectors 7 of the central paving surface 6 is performed until the maintenance state is reached. The radial movement of the sectors 7 of the central paving surface 6 also pulls the sectors 5 of the lateral paving surfaces 3, 4 into the maintenance state.

[0105] The steering shaft 10 includes a plurality of openings 15, each of which is passed through a bracket (not shown) connecting the crown 14 to the central shaft 2a. The openings 15 allow the steering shaft 10 to be rotated by the angular amount required for the contraction and expansion sectors without setting the central shaft 2a in rotation.

[0106] The rotation of the drum 1 about the geometric axis X is obtained by rotating the central shaft 2a, which sets the carriage in rotation and the crown 14 in rotation with the carriage. The rotation of the crown 14 determines the rotation of the telescopic supports 13 of the sectors 5 of the lateral laying surfaces 3, 4 and therefore of the supports 2c of the sectors 5, which sets the supports 2d of the sectors 7 of the central laying surface 6 in rotation. The rotation of the supports 2d of the sectors 7 of the central laying surface 6 sets the steering ring 11 in rotation, which in turn sets the steering shaft 10 in rotation. In this way, the central shaft 2a and the steering shaft 10 rotate as a unit with each other, the lateral laying surfaces 3, 4 and the central laying surface 6 remaining in the radial position occupied during the rotation of the drum 1.

[0107] The central body 2 also comprises adjustment linkages (not shown) configured to move the two lateral laying surfaces 3, 4 axially towards and away from each other and to define different axial dimensions for the forming drum 1.

[0108] As an example, the adjustment linkage may comprise an adjustment shaft coaxial with the central axis 2a, the adjustment shaft being provided with a threaded portion engaging with a corresponding internally threaded slide.A bracket connected to the crown 14 is mounted on the slide.

[0109] By rotating the adjustment shaft relative to the central shaft 2a, the slides are axially translated towards and away from each other, depending on the direction of mutual rotation between the central shaft 2a and the adjustment shaft, driven by the threaded portion of the adjustment shaft. The two slides axially move the crown 14 to which the sectors 5 of the lateral paving surfaces 3, 4 are constrained via the telescopic support 13. The sectors 5 of the two lateral paving surfaces 3, 4 can be moved towards or away from each other because they are moved by the rods 16 ( Figure 3 The rod 16 is oriented in the axial direction and may be telescopic (to shorten and lengthen) or may be coupled to the sector 5 so that the sector 5 can translate axially along the rod 16. The rod 16 is arranged between the supports 2c of the sectors 5 of the lateral paving surfaces 3, 4 and the supports 2d of the sectors 7 of the central paving surface 6 to constrain the supports 2c, 2d in rotation with respect to each other.

[0110] Coupling members 17 configured to removably retain the sectors 5 to the central body 2 are active between the sectors 5 , 7 and the central body 2 .

[0111] The coupling member 17 allows the removal and insertion of the sectors 5 and 7 on the central body 2 .

[0112] In the remainder of this description, reference will be made to the coupling member 17 associated with one sector 5 of the lateral paved surfaces 3, 4, however it will be understood that what is described also applies to all other sectors 5 and to the sector 7 of the central paved surface 6, unless expressly stated otherwise.

[0113] In a preferred embodiment of the invention, two coupling members 17 act between each sector 5 and the central body 2 ( Figure 4 ).

[0114] Each coupling member 17 comprises a first element 18 configured to engage a second element 19, such that the mutual engagement between the first element 18 and the second element 19 defines a retention state of the sector 5 in which the sector 5 is constrained to the central body 2 in the radial direction, such as Figure 5 When the first element 18 and the second element 19 are disengaged, as shown in Figure 6 As shown, a released state of the sector 5 is defined, in which the sector 5 can be removed from the central body 2 .

[0115] The first element 18 comprises a first part 20 which is rotatably constrained to the sector 5. The first part 20 comprises a connecting hinge 21 connected to the sector 5 so as to allow the first part 20 to rotate around the axial direction. The hinge 21 is made, for example, of a pin 21a fixedly connected to the sector 5, which engages a hole in the first part 20, such as Figure 7 Shown schematically.

[0116] The first element 18 also comprises a second portion 22 located distally of the first portion 20 and integral with the first portion 20, said second portion executing an arc path along a radial plane when the first portion 20 rotates about the hinge 21. The second portion 22 of the first element 18 comprises a slot 23 having an arched extension. The slot 23 is open at a first end 23a and is closed by a wall of the second portion 22 at a second end 23b opposite to the first end 23a ( Figure 6 ). The slot 23 is delimited in radial direction by an appendage 24 of the second portion 22 .

[0117] The second elements 19 are movably connected to the central body 2. Each second element 19 acting on the sectors 5 of the lateral paving surfaces 3, 4 is movably connected to the central body 2 at a radially external portion of the central body, in particular to a support 2c connected in a radially external position to the end of the respective telescopic support 13. Each second element 19 acting on the sectors 7 of the central paving surface 6 is movably connected to the central body 2 at a radially external portion of the central body, in particular to a support 2d connected in a radially external position to the respective connecting rod 12.

[0118] The second element 19 of each coupling member 17 comprises a first portion 25 configured to retain the first element 18 in a radial direction and a second portion 26 configured to retain the first element 18 in an axial direction.

[0119] The first portion 25 has a substantially axial extension and comprises a pin 27 ( Fig. 9 ). The pin 27 movably engages the seat 28 so as to be able to slide axially in the seat 28. For this purpose, the pin 27 comprises a threaded outer surface 27a and the seat 28 comprises an inner thread configured to couple with the threaded outer surface 27a of the pin 27. By screwing the pin 27 into the seat 28, the pin 27 increases its penetration inside the seat 28. By unscrewing the pin 27 from the seat 28, the pin 27 decreases its penetration inside the seat 28. The diameter of the pin 27 and the size of the slot 23 of the second portion 22 of the first element 18 are selected so that the pin 27 can be received inside the slot 23.

[0120] The second portion 26 of the second element 19 comprises a head 29. The head 29 is arranged at the end of the pin 27, in particular at the end of the pin 27 opposite to the end engaging the seat 28 in the central body 2, as shown in FIG. Figure 7 The head 29 is preferably integral with the pin 27 and has a larger diameter than the diameter of the pin 27. The diameter of the head 29 is selected so as not to allow the head 29 to be received inside the slot 23 of the first element 18. In a preferred embodiment of the present invention, the head 29 includes a manipulation seat 30 configured to be engaged by a manipulation tool (e.g., an Allen wrench) and to allow axial movement of the pin 27 within the seat 28.

[0121] like Fig. 9 As better shown in , the sector 5 comprises a spacer 31 for each coupling member 17. Each spacer 31 extends in a radial direction from the radial inner surface 5b of the sector 5 towards the central body 2. Each spacer 31 comprises two shoulders 32 spaced apart from each other. A substantially arched connecting surface 33 is provided between the two shoulders 32. The two shoulders 32 extend in a radial direction from the connecting surface 33. The distance separating the two shoulders 32 is greater than the diameter of the pin 27, so that the pin 27 can be accommodated between the two shoulders 32 at the connecting surface 33. Each spacer 31 comprises at least one abutment surface 31a intended to contact an abutment surface 2b provided on the central body 2. Each abutment surface 31a of the spacer 31 is formed at the end of the shoulder 32 on the side opposite to the radial inner surface 5b of the sector 5.

[0122] The first element 18 of the coupling member 17 is articulated on the spacer 31 in a radially outer position relative to the abutment surface 33. In other words, the articulation point between the first element 18 and the spacer is radially interposed between the radially inner surface 5b of the sector 5 and the abutment surface 33.

[0123] The radial dimension of the spacer 31 is selected according to the radial dimension that the forming drum 1 must have. The circumferential dimension of the radial outer surface 5a of the segment 5 is also selected according to the radial dimension that the forming drum 1 must have. In particular, the larger the radial dimension of the spacer 31, the larger the circumferential dimension of the radial outer surface 5a of the segment 5. The smaller the radial dimension of the spacer 31, the smaller the circumferential dimension of the radial outer surface 5a of the segment 5.

[0124] As mentioned above, for each sector 5, two coupling members 17 are provided. The coupling members 17 are arranged symmetrically with respect to a radial plane passing through the sector 5. In particular, the sector 5 is symmetrical with respect to a radial symmetry plane PS, and the coupling members 17 are arranged symmetrically with respect to the same radial symmetry plane PS ( Figure 4 ).

[0125] In order to vary the radial dimensions of the lateral laying surfaces 3, 4 and the central laying surface 6 of the forming drum 1, the operations described below are performed.

[0126] When the forming drum is in use, the sectors 5, 7 are constrained to the central body 2, with the first element 18 in a retaining state, in which it engages the first portion 25 of the second element 19 and radially retains the sectors 5, 7 to the central body 2, and the second element 19 in a retaining state, in which the second portion 26 of the second element 19 locks the first element 18 in a respective retaining state, thereby preventing any axial movement of the sectors 5 relative to the central body 2. This configuration is Figure 5 Shown in.

[0127] In this case, the second portion 22 of the first element 18 is rotated so that the slot 23 receives the pin 27 of the second element 19. The appendage 24 of the second portion 22 of the first element 18 prevents the sectors 5, 7 from being able to move in a radially outward direction relative to the central body 2. The pin 27 is inserted in the seat 28 to such an extent that the head 29 axially contacts the edge of the slot 23 and preferably presses lightly on the edge of the slot 23, preventing the first element 18 from rotating.

[0128] Starting from this configuration, the second portion 26 of the second element 19 enters a released state in which it is axially spaced apart from the first element 18. Such an operation is performed by partially extracting the pin 27 from the seat 28. In particular, the operator acts on the operating seat 30 of the head 29 of the second element 19 with a manipulating tool and partially unscrews the pin 27 from the seat 28.

[0129] The released state of the second portion 26 of the second element 19 determines the elimination of the axial constraint of the first element 18 and thus of the sectors 5, 7. This creates an axial gap between the sectors 5, 7 and the central body 2. This situation is Figure 7 Shown in.

[0130] The first element 18 is thus rotated to reach a release state in which the pin 27 is extracted from the slot 23. The appendage 24 of the second portion 22 of the first element 18 is no longer in contact with the second element 19 and is no longer able to radially retain the sectors 5, 7 on the central body 2. This situation is Figure 6 Shown in.

[0131] At this time, the operator can space the sectors 5 and 7 away from the central body 2 ( Figure 8 and 9 ).

[0132] In particular, in order to space the sectors 5 of the lateral paving surfaces 3 , 4 , each sector 5 is axially spaced from the central body 2 .

[0133] At least in a first step, the sectors 5 are spaced apart from the central body 2 and guided in the axial direction by the shoulders 32 of the spacers 31 , between which the second elements 19 are arranged.

[0134] In order to space the sectors 7 of the central paving surface 6 , each sector 7 is radially spaced from the central body 2 .

[0135] At least in a first step, the sectors 7 are spaced apart from the central body 2 and guided in the radial direction by the shoulders 32 of the spacers 31 , between which the second elements 19 are arranged.

[0136] All the sectors 5, 7 have been removed, new sectors 5, 7 are inserted on the central body, the circumferential dimensions of the radial outer surface 5a of the new sectors are different from the circumferential dimensions of the radial outer surface 5a of the removed sectors 5, 7, and the new sectors are equipped with spacers 31 having dimensions different from the dimensions of the spacers 31 of the removed sectors 5, 7.

[0137] Each new sector 7 of the central paved surface 6 moves radially towards the central body 2 ( Figure 8 , 9 ) so that the spacer 31 is at least roughly aligned with the second element 19.

[0138] Each new sector 5 of the lateral laying surface 3 , 4 is moved axially towards the central body 2 in order to bring the spacers 31 at least approximately into alignment with the second elements 19 .

[0139] In both cases, the new sectors 5, 7 are slotted onto the central body 2 so that the second elements 19 are arranged between the shoulders 32 of the spacers 31 and so that the abutment surfaces 31a of the spacers 31 abut against the abutment surfaces 2b of the central body 2. Figure 6 As shown, since both the second portion 26 of the second element 19 and the first element 18 are in the released state, there is an axial and radial space between the new sector 5 , 7 and the central body 2 .

[0140] The first element 18 is rotated so that the pin 27 of the second element 19 is inserted in the slot 23 of the first element 18. After such a rotation, the appendage 24 of the second portion 22 of the first element 18 is positioned radially below the pin 27 and prevents the new sector 5, 7 from moving radially relative to the central body 2. The first element 18 is thus transferred from the released state to the retained state, while the second element 19 remains in the released state. This situation is Figure 7 Shown in.

[0141] At this point, the second element 19 enters a holding state. In particular, the second portion 26 of the second element 19 is axially moved closer to the first element 18. This operation is performed by increasing the insertion degree of the pin 27 in the seat 28. In particular, the operator acts on the manipulation seat 30 of the head 29 of the second element 19 with a manipulation tool and screws the pin 27 into the seat 28. The pin 27 is inserted into the seat 28 to such an insertion degree that the head 29 axially contacts the edge of the slot 23, preferably lightly presses on the edge of the slot 23, preventing the first element 18 from rotating.

[0142] The retention of the second portion 26 of the second element 19 determines the axial restraint of the first element 18, thereby determining the axial restraint of the sectors 5, 7, and completing the replacement of the sectors 5, 7. Figure 5 Shown in.

[0143] The replacement operation is completed by inserting all new sectors 5 , 7 onto the central body 2 .

[0144] The invention has been described with reference to some preferred embodiments. Various modifications may be made to the embodiments described above while still remaining within the scope of protection of the invention as defined by the following claims.

Claims

1. A forming drum (1) for producing tyres for vehicle wheels, comprising: a central axis (2a) concentric with the geometrical axis of rotation (X) of the forming drum (1); a plurality of sectors (5, 7) arranged circumferentially around the central axis (2a) to define at least one paved surface (3, 4, 6); a central body (2) connected to the central axis (2a) and the plurality of sectors (5, 7) so as to arrange the plurality of sectors (5, 7) to rotate around the central axis (2a); a coupling member (17) operating between each of the plurality of sectors (5, 7) and the central body (2), the coupling member being configured to retain each sector to the central body (2) and to release each sector from the central body; wherein each coupling member (17) comprises a first element (18) movably connected to one of the central body (2) and the sectors (5, 7) and a second element (19) movably connected to the other of the central body (2) and the sectors (5, 7), the second element comprising a first portion (25) and a second portion (26); wherein the first element (18) is configured to move between a holding state, in which the first element engages a first portion (25) of the second element (19) and radially holds the sectors (5, 7) to the central body (2), and a release state, in which the first element disengages from the first portion (25) of the second element (19) and radially releases the sectors (5, 7) from the central body (2); The second element (19) is configured to move between a holding state and a release state, wherein the second portion (26) locks the first element (18) in a corresponding holding state, and the second portion (26) is axially spaced from the first element (18) and allows the first element (18) to reach a corresponding release state.

2. The forming drum (1) according to claim 1, wherein: The first element (18) moves in a radial plane between a retaining state and a release state and between the release state and the retaining state to engage and disengage the first portion (25) of the second element (19).

3. A forming drum (1) according to claim 1 or 2, wherein: The first element (18) performs a rotation about an axial direction to switch from a holding state to a releasing state and from the releasing state to a holding state.

4. A forming drum (1) according to claim 1 or 2, wherein: The first portion (25) of the second element (19) is configured to move axially and to move the second portion (26) of the second element (19) between a retaining state and a releasing state.

5. A forming drum (1) according to claim 1 or 2, wherein: The first element (18) comprises a first portion (20) rotatably connected to the central body (2) and one of the sectors (5, 7) and a second portion (22) located distal to the first portion (20), the second portion being configured to move in a circular path and intercept the first portion (25) of the second element (19) during a transition from a release state to a retention state.

6. A forming drum (1) according to claim 1 or 2, wherein: The first portion (25) of the second element (19) comprises a pin (27) extending in an axial direction, and wherein the second portion (26) of the second element (19) comprises a head (29) arranged at the end of the pin (27); the radial dimension of the head (29) is greater than the radial dimension of the pin (27).

7. A forming drum (1) according to claim 5, wherein: The first portion (25) of the second element (19) includes a pin (27) extending in an axial direction, and wherein the second portion (26) of the second element (19) includes a head (29) arranged at the end of the pin (27); the radial dimension of the head (29) is greater than the radial dimension of the pin (27); and wherein the second portion (22) of the first element (18) includes a slot (23) having an arched shape and opening at a first end (23a), and when the first element (18) is in a retained state, the slot (23) is configured to accommodate the pin (27) of the second element (19).

8. A forming drum (1) according to claim 7, wherein: When the first element (18) and the second element (19) are in a corresponding holding state, the head (29) of the second element (19) contacts the edge of the slot (23).

9. A forming drum (1) according to claim 1 or 2, wherein: The first element (18) is movably connected to the sectors (5, 7), and wherein the second element (19) is movably connected to the central body (2).

10. A forming drum (1) according to claim 1 or 2, wherein: Each sector comprises at least one spacer (31) extending away from the radial inner surface (5a) of the sector; the first element (18) of the coupling member (17) is movably coupled to the at least one spacer (31) of each sector.

11. A forming drum (1) according to claim 10, wherein: The spacer (31) comprises two shoulders (32) and a connecting surface (33) arranged between the two shoulders (32), the connecting surface (33) being configured to receive the first portion (25) of the second element (19) of the coupling member (17) between the two shoulders (32).

12. A forming drum (1) according to claim 11, wherein: When the first element (18) and the second element (19) of the coupling member (17) are in their respective retaining states, the second portion (26) of the second element (19) presses the first element (18) axially against the two shoulders (32) of the spacer (31).

13. A forming drum (1) according to claim 12, wherein: The first element (18) is arranged axially between the second portion (26) of the second element (19) and the spacer (31).

14. A forming drum (1) according to claim 1 or 2, wherein: The first portion (25) of the second element (19) comprises a threaded outer surface (27a) and is screwed into a seat (28) formed in the central body (2) with an insertion depth; the conversion of the second element (19) from the release state to the retention state is performed by increasing the insertion depth of the first portion (25) of the second element (19) in the seat (28) of the central body (2).

15. A forming drum (1) according to claim 14, wherein: The second portion (26) of the second element (19) is configured to control the insertion depth of the first portion (25) of the second element (19) in the seat (28) formed in the central body (2).

16. A method for changing the geometry of a forming drum (1) for producing tyres for vehicle wheels, comprising: The laying surfaces (3, 4, 6) are arranged by sectors (5, 7) which are arranged circumferentially around the central axis (2a) and are removably coupled to the central body (2); arranging for each sector a coupling member (17) comprising a first element (18) movably connected to one of the central body (2) and the sector and a second element (19) movably connected to the other of the central body (2) and the sector, the second element comprising a first part (25) and a second part (26); Changing the laying surface (3, 4, 6) by removing the sectors (5, 7) from the central body (2) and inserting new sectors on the central body (2); Wherein, removing the sectors (5, 7) from the central body (2) comprises: for each sector, moving the second portion (26) of the second element (19) axially away from the first element (18) to disengage the first element (18) from the first portion (25) of the second element (19) and to move the sectors (5, 7) away from the central body (2); And wherein inserting new sectors on the central body (2) comprises: for each new sector, The new sector is moved towards the central body (2), the first element (18) is moved so as to engage the first element with the first portion (25) of the second element (19), and the second portion (26) of the second element (19) is moved axially towards the first element (18) until the first element (18) is locked.

17. The method according to claim 16, wherein: Disengaging the first element (18) from the first portion (25) of the second element (19) comprises rotating the first element (18) around an axial direction from a corresponding holding state of the first element (18) to a corresponding release state, in which the first element engages the first portion (25) of the second element (19) and radially holds the sector (5, 7) to the center body (2), and in which the first element disengages from the first portion (25) of the second element (19) and radially releases the sector (5, 7) from the center body (2).

18. The method according to claim 16 or 17, wherein: Engaging the first element (18) with the first portion (25) of the second element (19) comprises rotating the first element (18) around the axial direction from a corresponding release state, in which the first element is disengaged from the first portion (25) of the second element (19) until a corresponding retention state, in which the first element engages with the first portion (25) of the second element (19) and radially retains the new sector to the center body (2).

19. The method according to claim 16 or 17, wherein: Moving the second portion (26) of the second element (19) axially away from the first element (18) includes: axially moving the second element (19) from a corresponding holding state to a corresponding release state, in which the second portion (26) locks the first element (18) in the corresponding holding state, and in the corresponding release state, the second portion (26) is axially moved away from the first element (18) and allows the first element (18) to reach the corresponding release state.

20. The method according to claim 16 or 17, wherein: Causing the second portion (26) of the second element (19) to axially move toward the first element (18) until the first element (18) is locked includes: axially moving the second element (19) from a corresponding release state to a corresponding retaining state, in which the second portion (26) of the second element (19) is axially spaced from the first element (18), and in which the second portion (26) of the second element (19) locks the first element (18) in the corresponding retaining state.

21. The method according to claim 16 or 17, wherein: Moving the new sector toward the center body (2) comprises: arranging a spacer (31) on the radial inner surface (5a) of the new sector, equipping the spacer (31) with at least one abutment surface (31a), the abutment surface being located on the far side of the radial inner surface of the new sector, and bringing the abutment surface (31a) of the spacer (31) into contact with the abutment surface (2b) of the center body (2).

22. The method according to claim 16 or 17, wherein: Moving the sectors (5, 7) away from the center body (2) comprises: arranging a spacer (31) on the radial inner surface (5a) of the sectors, providing the spacer (31) with at least one abutment surface (31a), the abutment surface being located on the far side of the radial inner surface of the sectors (5, 7), and moving the abutment surface (31a) of the spacer (31) away from the abutment surface (2b) of the center body (2).

23. The method according to claim 16 or 17, wherein: Disengaging the first element (18) from the first portion (25) of the second element (19) comprises: arranging the first element (18) to have a slot (23) having an arched shape and opening at a first end (23a), and rotating the first element (18) so that the first portion (25) of the second element (19) comes out of the slot (23).

24. The method according to claim 16 or 17, wherein: Engaging the first element (18) with the first portion (25) of the second element (19) comprises: arranging the first element (18) to have a slot (23) having an arched shape and opening at a first end (23a), rotating the first element (18) so that the first portion (25) of the second element (19) is inserted into the slot (23).

25. The method according to claim 23, wherein: Engaging the first element (18) with the first portion (25) of the second element (19) comprises: arranging the first element (18) to have a slot (23) having an arched shape and opening at a first end (23a), rotating the first element (18) so that the first portion (25) of the second element (19) is inserted into the slot (23); and wherein rotating the first element (18) so that the first portion (25) of the second element (19) comes out of the slot (23) and rotating the first element (18) so that the first portion (25) of the second element (19) is inserted into the slot (23) are performed in opposite angular directions.

26. The method according to claim 16 or 17, wherein: Axially moving the second portion (26) of the second element (19) toward the first element (18) comprises arranging the second portion (26) of the second element (19) to have a head (29) and causing the head (29) to abut axially against the first element (18).

27. The method according to claim 16 or 17, wherein: Moving the second portion (26) of the second element (19) axially away from the first element (18) comprises arranging the first portion (25) of the second element (19) to have a pin (27) with a threaded outer surface (27a) and partially unscrewing the pin (27) from the seat (28).

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