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

The carcass structure is associated with a crown structure which can comprise one or more belt layers, situated radially superimposed on each other and with respect to the carcass ply, having textile or metallic reinforcement cords with cross orientation and/or substantially parallel to the circumferential extension direction of the tyre (at <NUM> degrees). In radially outer position with respect to the belt layers, a tread band is applied, it too made of elastomeric material like other semifinished products constituting the tyre.

Respective sidewalls made of elastomeric material are also 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 with the beads. In the tyres of "tubeless" type, an air-impermeable coating layer, usually termed "liner", covers the inner surfaces of the tyre.

Following the building of the green tyre actuated by assembly of respective components, a moulding and vulcanisation treatment is generally executed aimed to determine the structural stabilisation of the tyre by cross-linking of the elastomeric compositions as well to impart on the same, if requested, a desired tread pattern and possible distinctive graphic marks at the sidewalls.

The terms "radial" and "axial" and the expressions "radially inner/outer" and "axially inner/outer" are used with reference to the radial direction of the annular body of a used support structure and/or of an annular component of a tyre (i.e. to a direction perpendicular to a central axis of the annular body and/or to the rotation axis of the aforesaid tyre) and to the axial direction of the annular body and/or of the tyre (i.e. to a direction parallel to the central axis or to the rotation axis of the tyre). The terms "circumferential" and "circumferentially" are instead used with reference to the annular extension of the aforesaid annular support and/or annular component of a tyre.

By "annular component" of a tyre, it is intended a green tyre or any one component thereof shaped as a ring around a central axis coinciding with the rotation axis of the tyre itself. Annular components for example include the carcass ply/plies, the bead cores, the tread band, the belt layer/layers, the tread band, the sidewalls, as well as a set composed of two or more of such components that are mutually coupled, such as for example the carcass structure comprising at least one carcass ply associated with the bead cores, and the crown structure comprising at least one or more belt layers and the tread band.

By "feeler pin" it is intended an abutment element projecting from a gripping element and movable with respect to the gripping element in order to be abutted against a surface of an annular component while the gripping element translates towards the latter.

During the process of building a tyre, one or more of its annular components must be picked up and suitably retained for the purpose of transfer into different work stations and/or for the coupling with other tyre parts. For example the carcass structure, typically made in cylindrical sleeve form, and the crown structure are generally made separately from each other in respective work areas, in order to be mutually assembled at a later time. For the purpose of the mutual assembly, it may be requested that one of these, for example the crown structure, be picked up from a respective forming drum, in order to be transferred and positioned coaxially centred around the carcass structure, supported by a respective building drum.

Hence, gripping apparatuses are normally applied in a production line, which are suitable for performing the operations of picking up, support and positioning of the crown structure, of the carcass structure and/or of other annular components, for the purpose of their coupling with other parts of the tyre being processed.

The document <CIT> describes a gripping apparatus which comprises an annular body arranged on a base reciprocally movable along a slide guide; the annular body is provided with telescopic mechanisms comprising blocks for magnetic attraction of a tyre body and locking cylinders; the magnetic attraction blocks are connected in a fixed manner with connecting rods of the locking cylinders; the connecting rods are aligned with the centre of the annular body.

The document <CIT> describes a control system with self-adaptive gripping having a ring situated on a machine for tyre construction, comprising electric servo-cylinders, for driving the movement of plates carrying load cells connected to a PLC. The PLC detects the feedback of the tightening force from the load cells and interrupts the actuation of the electric servo-cylinders upon reaching a nominal tightening force.

The Applicant has nevertheless observed that the apparatuses of the type for example described in the aforesaid documents are not adapted for offering a satisfactory gripping action on annular components having geometric and/or size characteristics that are different from those dictated by the design specifications, based on which the apparatuses themselves are constructed. In particular, the Applicant has perceived that when the known apparatuses are used for handling annular components having size and/or geometric characteristics different from those for which they were built, the action on the annular component being processed by the elements set to come into contact therewith does not result distributed and/or applied in a sufficiently appropriate manner, with the consequent tendency to cause twisting or deformations on the component itself, which can negatively affect the coupling precision with other parts of the tyre being processed and, consequently, on the quality of the final product.

This circumstance makes it difficult to use the known apparatuses in production lines where for example it can be requested to build small batches of tyres having dimensions and/or geometric characteristics that are different from each other, especially where the production requirements impose maximum quality standards, as takes place for example in the production of tyres for ultra-high performance vehicles or intended for use in sports competitions.

Consequently, each time it is necessary to process tyres that require annular components with different geometric and/or size characteristics, at the present state of the art it is necessary to intervene on the gripping apparatuses in order to substitute and/or make the necessary adjustments of the elements set for contacting the annular components of the tyres being processed, with consequent production losses deriving from the processing down times necessary for the setting.

The Applicant has therefore identified the opportunity to simplify the production processes by reducing or cancelling the setting operations for the apparatuses for gripping the annular components.

More particularly, the Applicant has perceived that in order to be able to manage the production of tyres having technical specifications that are different from each other, it is convenient to arrange gripping apparatuses that are capable of being autonomously adapted to the geometric and/or size characteristics of the annular components being processed at each production cycle, thus also managing a plurality of "single batches", i.e. batches formed by single tyres that are different from each other.

The Applicant has finally found that, by arranging gripping elements conceived such that the physical contact on the annular component itself is entrusted to the distributed action of a plurality of feeler pins that are separately positionable so as to copy the shape thereof, the gripping action is spontaneously adapted to the geometric and/or size characteristics of each annular component being processed.

In accordance with one aspect, the invention relates to gripping method for annular components of tyres for vehicle wheels, according to claim <NUM>.

In accordance with a further aspect, the invention relates to gripping apparatus for annular components of tyres for vehicle wheels, according to claim <NUM>.

The Applicant deems that by engaging the annular component by feeler pins movable with respect to the gripping elements and lockable against the annular component itself, a spontaneous adaptation is allowed of the shaping of the gripping elements to the geometric characteristics of the component itself, facilitating a more precise and stable engagement of the latter for the purpose of its movement and/or transfer in the absence of deformations. It is also possible to engage, in an equally facilitated and safe manner, annular components having different diameters from each other, and/or whose radially outer surfaces have a cross sectional profile different from each other, without having to intervene on the gripping apparatus with substitutions and adjustments of parts in order to adapt it each time to different shaping and/or dimensions of the annular components themselves.

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

Preferably, the feeler pins locked with respect to the gripping elements each have their own distal end acting in contact against the annular component.

The sum of the actions of the distal ends of the feeler pins facilitates an effective retention of the annular component, uniformly distributing the stresses on the latter, minimizing localized tensions and consequent possible deformations. Preferably, the distal ends each act against a radially outer surface of the annular component.

Preferably, the distal ends project with respect to the gripping elements in radially inner position.

Preferably, each feeler pin comes into contact with the annular component by a respective distal end opposite a proximal portion slidably engaged with the respective gripping element.

Preferably, at least before the radially approaching, the feeler pins are elastically pushed towards the central axis.

The elastic thrust action on the feeler pins allows bringing the same back into the position projecting from the respective gripping elements in order to arrange them in contact with the annular component.

Preferably, the locking of the feeler pins with respect to the gripping elements takes place by frictional forces.

It is thus possible to lock each feeler pin in any position along a sliding direction thereof with respect to the gripping element.

Preferably, the frictional forces are produced by pushing brake inserts against the feeler pins.

Preferably, the brake inserts are pushed against each feeler pin transversely to a sliding direction of the feeler pin with respect to the gripping element.

Preferably, the feeler pins are guided with respect to the gripping elements each along a sliding direction parallel to a radial approach direction of the gripping element with respect to the central axis.

Preferably, provision is also made for magnetically retaining the annular component against the feeler pins.

An effective retention of annular components comprising metallic inserts is thus facilitated, even if said components should have a particularly limited structural consistency.

Preferably, during the positioning of the support structure the annular component is supported by a removable support drum.

The support offered by the support drum prevents uncontrolled sliding of the feeler pins with respect to the gripping elements during the continuation of the approaching, under the effect of the weight of the annular component.

Preferably, the support drum is removed from the annular component after the locking of the feeler pins with respect to the gripping elements.

Preferably, after removing the support drum, the action of inserting, in the annular component, an additional drum is actuated, such additional drum having a cross sectional profile different that of the support drum.

Preferably, after the removal of the support drum, the action of releasing the feeler pins with respect to the gripping elements is actuated.

Preferably, after the removal of the support drum, the action of expanding the additional drum to cause a radial expansion of the annular component is actuated.

Preferably, after the removal of the support drum, the action of translating the feeler pins radially with respect to the gripping elements to accommodate the radial expansion of the annular component, during the expansion of the additional drum is actuated.

Preferably, after the removal of the support drum, the action of locking the feeler pins again with respect to the gripping elements at the end of the radial expansion of the annular component is actuated.

Preferably, after the removal of the support drum, the action of removing the additional drum from the annular component is actuated.

It is therefore possible to shape the annular component according to desired geometric specifications, while the sliding of the feeler pins supports the deformations thereof in a controlled manner.

Preferably, before releasing the feeler pins, a preliminary expansion of the additional drum is actuated up to bringing an outer surface thereof in contact with an inner surface of the annular component.

The additional drum is therefore adapted to support the annular component, so as to prevent uncontrolled sliding of the feeler pins with respect to the gripping elements with releasing completed, due to the weight of the annular component.

Preferably, each feeler pin has a proximal portion slidably engaged with the plate-like body and a distal portion projecting in radially inner position from the plate-like body.

The projection of the distal portions ensures that the action of the gripping elements on the annular component takes place through the feeler pins.

Preferably, the gripping elements are movable simultaneously upon command of a ring nut rotatably carried by the support structure and actuatable in rotation around the central axis.

The synchronous movement of the gripping elements is thus obtained by a single command operating on the ring nut, facilitating an overall structural simplification.

Preferably, the ring nut engages a plurality of toothed pinions each of which rotatably engaged with the support structure and carries a cam constrained to a drive lever of one of the gripping elements.

Preferably, the feeler pins are movable radially with respect to the plate-like body, independently of each other.

An independent mobility of the feeler pins facilitates a uniform distribution of the stresses on the annular component being processed.

Preferably, each feeler pin has a shaping elongated along a respective radial movement direction.

A wide adaptability of the apparatus to the different shapes and sizes of the annular components being processed is thus facilitated.

Preferably, the plate-like body of each gripping element comprises a first plate and a second plate superimposed parallel to each other.

Preferably, each of the feeler pins is slidably engaged through the first plate and the second plate.

Preferably, the first plate carries through holes slidably crossed, each by one of the feeler pins.

Preferably, each feeler pin has at least one abutment shoulder acting against an edge of the respective through hole in the extracted position.

It is thus possible to arrange a precise mechanical reference for the positioning of the feeler pins in extracted position.

Preferably, the second plate has sliding seats, each slidably housing a proximal portion of one of the feeler pins.

Preferably, provision is also made for elastic elements for elastically pushing each feeler pin towards the respective extracted position.

Preferably, the elastic elements operate each within one of the sliding seats.

Preferably, provision is also made for an intermediate plate operatively arranged between the first plate and the second plate and having guide channels slidably crossed, each by one of said feeler pins.

Preferably, the intermediate plate mates with the first plate.

Preferably, the brake comprises one or more brake inserts activatable in thrusting relation against each of the feeler pins.

Preferably, each brake insert is made of elastomeric material. Preferably, each brake insert circumscribes at least one of the feeler pins at a through opening crossed by the feeler pin itself.

Preferably, the brake inserts are fixed to at least one actuation plate movable upon command of at least one thrust actuator to push the brake inserts against the feeler pins.

Preferably, provision is also made for two actuation plates mutually adjacent to each other and movable in respectively opposite directions to compress the brake inserts against the feeler pins.

The cooperation of the actuation plates therefore exerts a gripping action by means of opposite forces on each of the feeler pins.

Preferably, said at least one actuation plate has guide slots crossed by centring pins fixed with respect to the first and second plate.

Preferably, provision is also made for containment seats obtained on mutually facing surfaces of the actuation plates.

Preferably, each containment seat houses one of the brake inserts.

Preferably, each of the containment seats has a shaping complementary to that of the respective brake insert, so as to house it in substantial absence of mechanical clearance.

Preferably, said at least one thrust actuator operates between thrust flanges respectively carried each by one of the actuation plates.

Preferably, said at least one actuation plate is slidably engaged between the intermediate plate and one of said first and second plate.

Preferably, said at least one actuation plate is slidably engaged between the intermediate plate and the second plate.

Preferably, the thrust actuator comprises a plurality of fluid-dynamic cylinders interconnected in series one after the other.

It is therefore possible to sum the forces exerted on the thrust plates by each fluid-dynamic cylinder, in order to develop a high braking force without necessarily having to employ high supply pressures of the actuators.

Preferably, provision is also made for magnets operatively associated with the feeler pins.

Preferably, each of the magnets is carried by a distal end of one of the feeler pins.

The action of the magnets allows exploiting the presence of metallic inserts in the annular components, facilitating the manipulation thereof, even in cases in which their structural consistency is low.

Further characteristics and advantages will be clearer from the detailed description of a preferred but non-exclusive embodiment of a gripping method for annular components of tyres for vehicle wheels, and of a gripping apparatus conveniently usable for operating according to said method, 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:.

With reference to the abovementioned figures, reference number <NUM> overall indicated a gripping apparatus for annular components of tyres for vehicle wheels. The apparatus <NUM> is adapted for operating according to a gripping method for annular components of tyres for vehicle wheels in accordance with the present invention.

The apparatus <NUM> and the method actuatable thereby are conveniently usable in making tyres <NUM> (<FIG>) typically comprising at least one carcass ply <NUM> preferably internally covered by an impermeable layer of elastomeric material or so-called liner <NUM>. Two anchoring annular structures <NUM>, each comprising a so-called bead core 5a preferably carrying an elastomeric filler 5b in radially outer position, are engaged with respective terminal flaps 3a of the carcass ply/plies <NUM>. The anchoring annular structures <NUM> are integrated in proximity to zones normally identified with the name of "beads" <NUM>, at which the engagement between the tyre <NUM> and a respective mounting rim (not depicted) usually takes place.

A belt structure <NUM> is circumferentially applied around the carcass ply/plies <NUM>, and a tread band <NUM> is circumferentially superimposed on the belt structure <NUM>. Two sidewalls <NUM>, each extended from the corresponding bead <NUM> to a corresponding lateral edge of the tread band <NUM>, are applied in laterally opposite positions on the carcass ply/plies <NUM>.

For the purpose of attaining the tyre <NUM>, provision can be made for, e.g. according to known modes, making a carcass sleeve (not illustrated) having shaping substantially cylindrical, comprising said at least one carcass ply <NUM>, preferably internally covered by the liner <NUM>. If necessary, the carcass sleeve can also comprise the sidewalls <NUM> or first portions thereof, each extended starting from a respective bead <NUM>. The attainment of the carcass sleeve can for example be executed on a first support drum (not illustrated), usually identified as "building drum", on which the aforesaid components are formed and/or assembled according to a predetermined sequence.

On a further support drum, identified herein as "auxiliary drum" <NUM>, a so-called crown structure <NUM> can be obtained, comprising the belt structure <NUM>, possibly coupled with the tread band <NUM> and/or annular inserts of another type.

The crown structure <NUM> and the carcass sleeve are adapted to be mutually assembled in an assembly station (not illustrated) in which the carcass sleeve, typically supported by the same building drum in which it was attained or by a shaping drum on which it has been previously transferred, is radially expanded and toroidally shaped in order to be coupled with the crown structure <NUM> previously transferred into an axially centred position around the same carcass sleeve.

In the embodiment described hereinbelow, the apparatus <NUM> is adapted to be used for picking up the crown structure <NUM> from the auxiliary drum <NUM> and transferring it around the carcass sleeve arranged in the assembly station. In addition or as an alternative, the apparatus <NUM> is nevertheless conveniently usable, for example, for transferring the carcass sleeve from the building drum to the possible shaping drum, and/or for removing the assembled tyre <NUM> from the building drum and/or shaping drum, as well as for picking up any other annular component of a tyre <NUM> from a respective support drum during the production process.

The apparatus <NUM> comprises a support structure <NUM> arranged circumferentially around a central axis X. In the illustrated embodiment, the support structure <NUM> has a base <NUM> carrying an annular body <NUM> concentric with the central axis X. The base <NUM> can be slidably mounted on one or more linear guides <NUM>, in order to allow the translation of the support structure <NUM> parallel to the central axis X. For example, the support structure <NUM> can be movable between a pick-up position in which, as in <FIG>, it is preferably arranged in axially centred position around the auxiliary drum <NUM> carrying the crown structure <NUM>, and a release position (not illustrated) in which it is axially moved away from the auxiliary drum <NUM> and preferably arranged in axially centred position around the carcass sleeve carried by the building drum or by the possible shaping drum, in order to allow the coupling thereof with the crown structure <NUM>.

The support structure <NUM> is associated with a plurality of gripping elements <NUM> carried by the annular body <NUM> and circumferentially distributed around the central axis X. Each of the gripping elements <NUM> is radially movable between a gripping position in which it is approached to the central axis X, and a release position in which it is moved away from the central axis X.

The movement of the gripping elements <NUM> is preferably controlled by a toothed ring nut <NUM> rotatably carried by the annular body <NUM> and carrying a circumferential toothing 17a which engages a plurality of toothed pinions 18a (<FIG>), each carried by a pin <NUM> rotatably engaged with the annular body <NUM> of the support structure <NUM>. Each toothed pinion 18a, or the pin <NUM> associated therewith, carries a cam <NUM> constrained to a drive lever <NUM> of one of the gripping elements <NUM>.

The toothed ring nut <NUM> is actuatable in angular rotation around the central axis X, for example upon action of a drive actuator (not illustrated) fixed to the base <NUM>, to cause - through the aforesaid toothed pinions 18a - the simultaneous translation of all the gripping elements <NUM> between the gripping position and the release position. Alternatively, the movement of the gripping elements <NUM> can be obtained by levers associated with the annular body <NUM> and activatable by the drive actuator, or by a plurality of actuators each operating on one of the same gripping elements <NUM>.

Each of the gripping elements <NUM> has a plate-like body <NUM> facing towards the central axis X, slidably crossed by a plurality of feeler pins <NUM> distributed for example according to rows and parallel lines, or according to any one other matrix scheme.

The feeler pins <NUM> are movable radially through the plate-like body <NUM>, independently of each other, between an extracted position in which protrude radially towards the central axis X (<FIG>) and a retracted position moving away from the central axis X (<FIG>). The feeler pins <NUM> could also have a different length so as to be able to follow the circumference of the annular component. In this case the central feeler pins would be shorter and the length could increase incrementally for each row of feeler pins <NUM> towards the ends of the gripping element <NUM>.

Preferably, as is more visible in <FIG>, the plate-like body <NUM> of each gripping element <NUM> comprises a first plate <NUM> and a second plate <NUM> superimposed parallel to each other. The first plate <NUM>, directed towards the central axis X, carries a plurality of through holes <NUM> while the second plate <NUM> has sliding seats <NUM> each aligned with one of the through holes <NUM> of the first plate <NUM>.

Each of the feeler pins <NUM>, having elongated shape along a respective radial movement direction, is slidably engaged through the first plate <NUM> and the second plate <NUM>.

More particularly, each feeler pin <NUM> has a proximal portion <NUM> slidably guided along one of the sliding seats <NUM> carried by the second plate <NUM>, according to a sliding direction parallel to the radial approach direction of the gripping element <NUM> with respect to the central axis X. From the proximal portion <NUM>, a distal portion <NUM> is extended which slidably crosses one of the through holes <NUM> of the first plate <NUM>, so as to project in radially inner position from the plate-like body <NUM>, with their own distal end 28a directed in the direction of the central axis X.

At least one return spring <NUM> or elastic elements of another type preferably operate within each of the sliding seats <NUM>, for elastically pushing each feeler pin <NUM> towards the respective extracted position.

Preferably, each feeler pin <NUM> has at least one abutment shoulder <NUM> which, in the illustrated example, delimits the distal portion <NUM> from the proximal portion <NUM>. The abutment shoulder <NUM> is adapted to act against one edge of the respective through hole <NUM>, in order to stop the travel of the feeler pin <NUM> by opposing the thrust action of the return spring <NUM> upon reaching the extracted position.

In the illustrated example, the abutment shoulders <NUM> are defined at the ends of respective grooves <NUM> made longitudinally on one or more side of the distal portion <NUM> of each feeler pin <NUM>. Each of the grooves <NUM> engages a perimeter projection 31a arranged on the edge of the respective through hole <NUM> arranged in the first plate <NUM>.

The first plate <NUM> can be made in the form of a thin plate, and preferably coupled to mate with an intermediate plate <NUM> operatively arranged between the first plate <NUM> and the second plate <NUM>. The guide function of the feeler pins <NUM> through each plate-like body <NUM> can be at least partially entrusted also to guide channels <NUM> obtained through the intermediate plate <NUM> and each slidably crossed by one of the feeler pins themselves.

Provision is also made such that between each of the plate-like bodies <NUM> and the respective feeler pins <NUM> at least one brake <NUM> is operatively arranged, preferably free transversely to a radial direction, selectively activatable in order to lock the feeler pins <NUM> themselves in any one intermediate working position between the extracted position and the retracted position.

As better visible in <FIG>, the brake <NUM> comprises one or more brake inserts <NUM>, preferably made of elastomeric material with high friction coefficient, activatable in thrusting relation against each of the feeler pins <NUM>.

Preferably, the brake inserts <NUM> are fixed to one or more actuation plates <NUM> and each have a through opening <NUM> circumscribing at least one of the feeler pins <NUM> which crosses the same brake insert <NUM> and actuation plates <NUM>. More particularly, two actuation plates <NUM> are preferably provided, mutually adjacent to each other and slidably engaged between the intermediate plate <NUM> and the second plate <NUM>.

On the mutually facing surfaces of the actuation plates <NUM>, containment seats <NUM> are made, and one of the brake inserts is inserted in each of these. Each of the containment seats <NUM> preferably has a shaping complementary to that of the respective brake insert <NUM>, so as to perimetrically contain it substantially without mechanical clearance.

The actuation plates <NUM> have guide slots <NUM> crossed by centring pins <NUM> fixed with respect to the first plate <NUM> and to the second plate <NUM>, as well as to the intermediate plate <NUM>. The actuation plates <NUM> are mutually slidable along the extension direction of the guide slots <NUM>, and movable in respectively opposite directions to push and compress the brake inserts <NUM> against the feeler pins <NUM>, transverse to the sliding direction of the latter with respect to the gripping element <NUM>.

The activation of the actuation plates <NUM> can be obtained upon command of at least one thrust actuator <NUM> operating between thrust flanges <NUM> perimetrically thrusting from each of the actuation plates <NUM>. The thrust actuator <NUM> can conveniently comprise a plurality of fluid-dynamic cylinders 41a interconnected in series one after the other so as to develop high thrust actions without requiring actuators with large diameter and/or high supply pressures.

In accordance with a gripping method according to the present invention, the use of the gripping apparatus provides that, with a translation along the linear guides <NUM>, the support structure <NUM> is positioned circumferentially around an annular component of a tyre <NUM> which, in the example described herein, is represented by the crown structure <NUM>. The crown structure <NUM> can be supported by the auxiliary drum <NUM> on which it was previously attained, and is adapted to be removed therefrom in order to be transferred to the assembly station for the purposes of its coupling with the carcass sleeve.

The annular body <NUM> of the support structure <NUM>, arranged with the gripping elements <NUM> in release position, translates coaxially with respect to the auxiliary drum <NUM> and is stopped in axially centred position around the crown structure <NUM>.

With an angular rotation imposed on the toothed ring nut <NUM>, the simultaneous translation of the gripping elements <NUM> towards the central axis X is thus driven, bringing the crown structure <NUM> close to the feeler pins <NUM> retained in the extracted position due to the return springs <NUM>.

When the distal ends 28a of the feeler pins <NUM> come into contact on the outer surface of the crown structure <NUM>, the radial approaching of the gripping elements <NUM> to the central axis X can conveniently proceed without interruptions. Since the brakes associated with the gripping elements <NUM> are deactivated, the gripping elements <NUM> are free to slide along the feeler pins <NUM> which came into contact with the crown structure <NUM>, overcoming the resistance of the return springs <NUM> and continuing with the further approaching of the possible feeler pins <NUM> that have not yet reached the outer surface of the crown structure <NUM>. Consequently, all the feeler pins <NUM> can progressively come into contact with the crown structure <NUM>, being abutted against its outer surface, while the gripping elements <NUM> continue their approach to the central axis X.

When the gripping elements <NUM> reach the gripping position, all the feeler pins <NUM> can therefore be in contact with the crown structure <NUM>, accurately copying the shaping of the outer surface. The activation of the thrust actuators <NUM> can then be driven, upon action of which the actuation plates <NUM> are thrust in respectively opposite directions, carrying the brake inserts <NUM> to exert opposite forces against the respective feeler pins <NUM>. Due to the consequent friction generated by the brake inserts <NUM> thrust against the feeler pins <NUM>, the latter remain suitably locked with respect to the gripping elements <NUM>, each distal end 28a abutted against the crown structure <NUM>, in the position assumed upon reaching the gripping position as in <FIG>.

Once the locking of the feeler pins <NUM> is executed with respect to the gripping elements <NUM>, the auxiliary drum <NUM> is adapted to be removed from the crown structure <NUM>, for example by radial contraction of the drum itself and subsequent axial removal. The action of abutment exerted by the feeler pins <NUM> on the outer surface of the crown structure <NUM> causes a suitable radial containment thereof and support in the absence of stresses and twisting, notwithstanding the absence of the support offered by the auxiliary drum <NUM> which was removed. The possible presence of magnets (not illustrated), each operatively associated at the distal end 28a of a respective feeler pin <NUM>, determines a retention of the crown structure <NUM> against the feeler pins <NUM> themselves, opposing undesired collapses thereof due to the weight, facilitating the action of support if the same crown structure <NUM> or other annular component has metal inserts or inserts made of another ferromagnetic material.

Once removed the auxiliary drum <NUM>, the crown structure <NUM> retained by the gripping elements <NUM> can be transferred into the assembly station for the purpose of coupling with the carcass sleeve. During coupling, the presence of the feeler pins <NUM> in contact with the crown structure <NUM> offers a suitable action of containment and contrast against possible thrust actions exerted radially towards the exterior of the carcass sleeve during shaping.

It may be requested that after the removal of the auxiliary drum <NUM> (or support drum of another type), the crown structure <NUM> (or another annular component of the tyre <NUM>) is subjected to further processing steps. For example, the processing of the crown structure <NUM> can require a shaping treatment aimed to impose on the same a desired cross sectional profile, different from that obtained during the attainment on the auxiliary drum <NUM>, before carrying out the coupling thereof with the carcass sleeve.

In this regard, in accordance with a possible embodiment variant of the invention, after the removal of the auxiliary drum <NUM> (or other support drum) from the crown structure <NUM>, provision can be made that in the latter (or other annular component of the tyre <NUM>), an additional drum <NUM> (<FIG>) is coaxially inserted, having a cross sectional profile different from that of the auxiliary drum <NUM> used above. For example, the additional drum <NUM> can have a convex cross sectional profile at the radially outer surface thereof, unlike the auxiliary drum <NUM> in which such cross sectional profile is typically rectilinear.

The engagement of the additional drum <NUM> can occur by axial movement of the same along the central axis X, or by axial movement of the support structure <NUM> along the linear guides <NUM>.

Upon completed insertion, a preliminary radial expansion of the additional drum <NUM> can be actuated up to bringing the outer surface thereof in contact with the inner surface of the crown structure <NUM>, as indicated with a dashed line in <FIG>. The thrust actuators <NUM> can then be deactivated thus to release the feeler pins <NUM> with respect to the gripping elements <NUM>, after which the additional drum <NUM> is adapted to be further expanded within the crown structure <NUM>, forcing the same to sustain a radial expansion in order to take on the convex cross sectional profile corresponding to that of the additional drum <NUM>, as in <FIG>.

The mobility of the feeler pins <NUM> allows the latter to radially translate with respect to the gripping elements <NUM>, in order to follow the deformations set to the crown structure <NUM> so as to support the radial expansion during the expansion of the additional drum <NUM>. During this step, the feeler pins <NUM> can be slightly rubbed. In order to obtain this effect, it is sufficient to reduce the pressure of the cylinders 41a which actuate the actuation plates <NUM> to which the brake inserts <NUM> are fixed.

Upon completed expansion, the thrust actuators <NUM> can be reactivated in order to again lock the feeler pins <NUM> with respect to the gripping elements <NUM>.

Claim 1:
Gripping method for annular components of tyres for vehicle wheels, comprising:
positioning a support structure (<NUM>) circumferentially around an annular component (<NUM>) of a tyre (<NUM>);
radially approaching, to the annular component (<NUM>), gripping elements (<NUM>) carried by the support structure (<NUM>) and circumferentially distributed around a central axis (X), the method being characterised by
bringing into contact on the annular component (<NUM>) a plurality of feeler pins (<NUM>) slidably carried by each of said gripping elements (<NUM>);
continuing radially approaching the gripping elements (<NUM>) to the annular component (<NUM>), making them slide along the feeler pins (<NUM>) which came into contact with the annular component (<NUM>) until the gripping elements (<NUM>) reach a gripping position; and
locking the feeler pins (<NUM>) with respect to the gripping elements (<NUM>).