Process and apparatus for building tyres

A continuous elongated element of elastomeric material is produced through an extruder at a linear delivery speed and directly fed onto a moving surface of a conveyor without interposition of other devices. The continuous elongated element is advanced on the moving surface along a predetermined direction and at a linear advancing speed different from the linear delivery speed until a proximal end of the conveyor. Subsequently, the continuous elongated element is applied onto a forming support which rotates relative to the proximal end of the conveyor at a peripheral speed different from the linear delivery speed, so as to deform the continuous elongated element and apply it in the form of wound coils onto the forming support in order to form a component of elastomeric material of a tyre.

CROSS REFERENCE TO RELATED APPLICATION

This application is a national phase application based on PCT/IT2008/000290, filed Apr. 23, 2008.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a process for building tyres and to an apparatus for building tyres operating in accordance with said process.

Description of the Related Art

A tyre generally comprises a carcass structure including at least one carcass ply having end flaps in engagement with respective annular anchoring structures, each usually formed of at least one substantially circumferential annular insert onto which at least one filling insert radially tapering away from the rotation axis is applied.

Associated with the carcass structure at a radially external position is a belt structure comprising one or more belt layers, arranged in radially superposed relationship relative to each other and to the carcass ply, provided with textile or metallic reinforcing cords having a crossed orientation and/or disposed substantially parallel to the circumferential extension direction of the tyre. At a radially external position to the belt structure, a tread band is applied which is also of elastomeric material like other semifinished products constituting the tyre.

A so-called “underlayer” of elastomeric material can be interposed between the tread band and the belt structure, which underlayer has properties adapted to ensure a steady union between belt structure and tread band.

Respective sidewalls of elastomeric material are further applied to the side surfaces of the carcass structure, each extending from one of the side edges of the tread band until close to the respective annular anchoring structure to the beads.

It is to be pointed out that, to the aims of the present description, by the term “elastomeric material” it is intended a compound comprising at least one elastomeric polymer and at least one reinforcing filler. Preferably this compound further comprises additives such as a cross-linking agent and/or a plasticizer. Due to the presence of the cross-linking agent, this material can be cross-linked through heating, so as to form the final product.

In tyres of the “tubeless type”, the carcass ply is fully coated with a layer of preferably butyl-based elastomeric material, usually referred to as “liner”, which has optimal airtightness features and extends from one of the beads to the other.

In tyres of the run-flat type or for other particular uses, the carcass structure can be further provided with auxiliary support inserts of elastomeric material, located at an axially internal position relative to each of the sidewalls. These auxiliary support inserts, usually called “sidewall inserts”, lend themselves to support loads transmitted to the wheel in case of accidental deflation of the tyre, to enable the vehicle to go on running under safety conditions.

In many known processes for manufacture of a tyre the carcass structure and belt structure as well as the tread band, sidewalls and any other elastomeric structural element are made separately of each other in respective work stations, and then stored in storage stations or warehouses from which they are subsequently picked up for mutual assembly along a tyre building line.

It is to be pointed out that by “component of elastomeric material” of the tyre in this context it is intended any part of elastomeric material in the tyre (e.g. the tread band, sidewalls, liner, under-liner, fillers in the bead region, sidewall inserts in run-flat tyres, abrasion-proof inserts, and so on), or portion thereof, or still the assembly formed of two or more of said parts or portions thereof.

More recently, production processes have been developed as the one described in document WO 01/36185 in the name of the same Applicant, in which the following steps are carried out for making tyre components of elastomeric material for vehicle wheels: feeding a continuous elongated element from a delivery member disposed adjacent to a toroidal support for applying said elongated element onto the toroidal support; giving the toroidal support a circumferential-distribution rotary motion around a geometric rotation axis thereof, so that the elongated element is circumferentially distributed on the toroidal support; carrying out controlled relative displacements for transverse distribution between toroidal support and delivery member in order to form a component of a tyre with said elongated element, which component is defined by a plurality of coils laid in approached and mutually superposed relationship according to a predetermined laying scheme depending on a predetermined cross-section profile to be given to said component; wherein the circumferential-distribution rotary movement is controlled as a function of the distance existing between an application point of the elongated element onto the toroidal support and said geometric rotation axis, to give the toroidal support, at the application point, a peripheral application speed having a nominal value greater than and proportional to a theoretical feeding speed of the elongated element by said delivery member.

EP 1 033 236 discloses an apparatus for making rubber components, such as components for tyres, comprising a unit provided with an extruder and a pair of compression rollers to produce an unvulcanised rubber tape, a winding drum around which the rubber tape is wound up to form one of said components, a conveyor for transport of the unvulcanised rubber tape towards the winding drum. The compression rollers form a slit adapted to compress and shape the extruded rubber into a rubber tape provided with a specific cross section. The conveyor comprises a conveyor belt wrapped around rollers and having a side on which the rubber tape is positioned. The conveyor consists of a section for receiving the rubber tape, a storage section and a device capable of moving the conveyor belt along an axial direction of the winding drum.

This device is provided with an end roller around which the conveyor belt is wrapped and from which the rubber tape is released towards the winding drum.

SUMMARY OF THE INVENTION

In this technical field, the Applicant has felt the necessity:to increase speed and improve efficiency of the production processes adapted to lay a continuous elongated element on a forming support;to increase reliability, speed and versatility of these apparatuses;to simplify structure of the apparatuses designed to carry out these production processes while reducing bulkiness;to improve quality of the produced continuous elongated element and quality of the manufactured tyres at least partly through laying of said element;to overcome process problems connected with use of rollers exerting pressure on the continuous elongated element, in particular those resulting from undesirable adhesion between the forming surfaces and the continuous elongated element.

The Applicant has verified that apparatuses of the type disclosed in EP 1 033 236 carrying out calendering of the tape immediately downstream of the extruder delivery opening to give said tape a correct section and subsequently feeding the tape through a complex series of mechanisms adapted to store it and stabilise it in size, are mechanically very complicated and, consequently, of reduced reliability, very expensive, of difficult setting and requiring frequent servicing interventions.

The Applicant has further found that the storage section described in said document makes the apparatus very bulky and this bulkiness on the whole adversely affects the plant's sizes. In fact, even when the rubber tape is not wound up around the drum, the conveyor belt goes on moving at a constant speed so as to build up the rubber tape until laying of same on the drum is started again. Therefore, the sizes of the storage section must be sufficient to enable this building-up operation.

In addition, the Applicant has noticed that each time the cross section of the rubber tape is required to be changed, the apparatus must be compulsorily stopped to replace the calender's rollers, which operation does not make the process very flexible.

The Applicant has then observed that apparatuses of the type described in document EP 1 033 236 could not operate should the material constituting the rubber tape be of such a nature that it does not adhere to the conveyor belt, because this rubber tape, once cutting has been completed, cannot be retained on the conveyor in any manner.

The Applicant has further perceived that where tyres are built on toroidal forming supports as described in WO 01/36185, it may be advantageous that deformation of the continuous elongated element be distributed in at least two distinct stages to obtain; on laying, the desired section of the continuous elongated element. In fact, in building processes carried out on toroidal supports, the component being formed must already have a shape very close to that of the finished product at the end of the vulcanisation and moulding step, because no shaping step is carried out. For the above reason, the continuous elongated element must take a shape sometimes very different from that imparted at the extruder's delivery opening, which situation can cause stresses and particular tensions thereon: consequently, division of the deformation to which it is submitted into several steps reduces stresses and tension, bringing about a reduction in the risks of obtaining a product to be discarded.

The Applicant has therefore found that it is possible to overcome the above described problems by eliminating calendering of the continuous elongated element of elastomeric material exiting the extruder, and carrying out a first longitudinal deformation of the continuous elongated element immediately downstream of said extruder and subsequently deforming the continuous elongated element until giving it the desired cross-section.

More particularly, in a first aspect, the present invention relates to a process for building tyres comprising the step of forming components of elastomeric material on a forming support, wherein at least one of said components of elastomeric material is made through the steps of:producing a continuous elongated element of elastomeric material by an extruder, which element has a linear delivery speed on coming out of said extruder;feeding the continuous elongated element directly on a moving surface of a conveyor without interposition of other devices;advancing said continuous elongated element of elastomeric material on the moving surface along a predetermined direction and at a linear advancing speed different from said linear delivery speed, until close to a proximal end of said conveyor adjacent to the forming support;applying the continuous elongated element into coils wound up on the forming support, to form said at least one component of elastomeric material of the tyre; said forming support rotating relative to the proximal end of the conveyor at a peripheral speed;
wherein the peripheral speed is different from the linear delivery speed, so as to deform the continuous elongated element.

In accordance with a second aspect, the present invention relates to an apparatus for building tyres, comprising:at least one forming support;at least one forming device to form components of elastomeric material on the forming support;
wherein said at least one forming device comprises:at least one extruder to deliver a continuous elongated element of elastomeric material at a linear delivery speed;at least one conveyor for said continuous elongated element having a moving surface along a predetermined direction at a linear advancing speed different from said linear delivery speed and towards a proximal end of the conveyor adjacent to the forming support;at least one device for application of said continuous elongated element onto said forming support, positioned close to the proximal end of the conveyor;devices for rotating said forming support on an axis thereof relative to the proximal end of the conveyor at a peripheral speed;wherein the extruder feeds the continuous elongated element directly onto the conveyor without interposition of other devices;wherein the peripheral speed is different from the linear delivery speed, so as to deform the continuous elongated element.

By adopting the process and apparatus in accordance with the invention, the Applicant has obtained a great structural simplification of the apparatus relative to those of the known art, a reduction in bulkiness, a reduction in the manufacturing and servicing costs of the apparatus, and increase in reliability and in the tyre production speed and flexibility.

In fact, it is possible to obtain the correct section of the continuous elongated element through deformation in two steps and without use of a calender. In addition, an extruder having a delivery opening of a section even greatly bigger than the section of the applied continuous elongated element can be used, since the desired section is obtained by drawing. Therefore, when the section of the applied continuous elongated element is to be changed, it is not necessary to change each time the calender and/or the flange of the extruder in which said delivery opening is formed and this ensures more flexibility to the apparatus. In addition, storage of the continuous elongated element is no longer required as it can be produced exactly at the moment of use, thus avoiding building-up of same, which would involve possible decay and waste of material.

The present invention, in at least one of the above mentioned aspects, can have one or more of the preferred features hereinafter described.

Preferably, the peripheral speed is higher than the linear delivery speed so as to draw the continuous elongated element.

Preferably, the peripheral speed is higher than or as high as about 1.2 times the linear delivery speed.

In addition, preferably, the peripheral speed is higher than or as high as about 1.3 times the linear delivery speed.

Preferably the peripheral speed is lower than or as high as about 1.6 times the linear delivery speed. Preferably, the peripheral speed is lower than or as high as about 7 times the linear delivery speed.

The amount of the speed increase relative to the extrusion speed depends on the features of the material of the continuous elongated element and on the section of the continuous elongated element that is wished to be obtained during laying.

According to a preferred embodiment, the peripheral speed is lower than the linear delivery speed, so as to compress the continuous elongated element.

Preferably, the peripheral speed is included between about 0.5 times and about 0.95 times the linear delivery speed.

More preferably, the peripheral speed is included between about 0.65 times and about 0.85 times the linear delivery speed.

According to a preferred embodiment of the process, the linear advancing speed is higher than the linear delivery speed.

In fact, it is advantageous that the longitudinal deformation of the continuous elongated element be carried out in two steps.

Preferably, the linear advancing speed is lower than or as high as about 1.5 times the linear delivery speed.

Drawing of the continuous elongated element in this manner is carried out in two subsequent steps, a first step immediately after exit from the extruder and a second step during application onto the forming support. Drawing in two steps allows damaging of the continuous elongated element to be eliminated or at least reduced. In fact, the continuous elongated element delivered from the extruder has high and uneven temperatures and pressures. If submitted to a single drawing operation in the conditions as delivered from the extruder in particular in case of critical, i.e. not very elastic, blends, the continuous elongated element becomes damaged because crackings and/or burrs are generated on its surface.

Laying and advancing on the moving surface of the conveyor carried out before the final application step allows the continuous elongated element to cool and take uniform pressure and temperature conditions, so that the subsequent second drawing step, obtained by means of an increase in the peripheral speed of the drum relative to the linear advancing speed of the conveyor, can be carried out without the quality of the continuous elongated element being impaired.

More preferably, the linear advancing speed is higher than or as high as about 1.005 times the linear delivery speed.

Alternatively, according to a preferred embodiment of the process, the linear advancing speed is lower than the linear delivery speed.

Preferably the linear advancing speed is higher than or as high as about 0.75 times the linear delivery speed.

More preferably, the linear advancing speed is lower than or as high as about 0.995 times the linear delivery speed.

In the first step, a compression operation is carried out in place of drawing, which compression is adapted to compensate for the cooling effects of the continuous elongated element coming out of the extruder. In fact, the continuous elongated element tends to contract during cooling. The cooling effect generates axial stresses in the continuous elongated element. Compression carried out when the blend of the continuous elongated element is still hot prevents formation of said stresses and avoids generation of crackings and/or burrs due to contraction, as said continuous elongated element gets cool.

According to a preferred embodiment of the process, the ratio of the linear advancing speed to the linear delivery speed is maintained constant during the step of applying said continuous elongated element.

Alternatively, the ratio of the linear advancing speed to the linear delivery speed is varied during the step of applying said continuous elongated element.

In addition, preferably, the ratio of the peripheral speed to the linear delivery speed is maintained constant during the step of applying said continuous elongated element.

Alternatively, the ratio between the peripheral speed and linear delivery speed is varied during the step of applying said continuous elongated element.

Variation in speeds during laying allows either possible variations in the features of the elongated elements to be actively compensated for, which variations are for example due to unexpected pressure and/or temperature variations, or the section of the elongated element and/or the laying speed to be varied based on previously established programs and/or on the shape of the laying surface of the forming support.

Preferably, the linear advancing speed is given to the continuous elongated element by pressing said continuous elongated element on the moving surface through at least one presser device.

This solution is simple from a structural point of view and in addition in case of blends containing fibres, such as the “kevlar pulp”, possibly allows a predetermined orientation to be given to these fibres while the blend is still hot.

Advantageously, at the end of application, the continuous elongated element is cut between the extruder and the conveyor.

While the continuous elongated element is being cut, the extruder is stopped. The length of the continuous elongated element remaining downstream of the cutting point passes onto the conveyor and is applied to the forming support. Therefore, management of long lengths of continuous elongated element remaining between the extruder and the forming support is not required between an application and the subsequent one. In addition, before a new application, routing of the continuous elongated element between the roller of the presser device and the conveyor belt is easy, because it is not required that said continuous elongated element be passed through the shaped slit of the calender, in which case the continuous elongated element would be also likely to remain attached to the calender's steel roller.

According to a preferred embodiment, the apparatus comprises a control unit operatively connected to the extruder, the conveyor and the devices for rotating said forming support on an axis thereof and adapted to control and adjust the linear delivery speed, linear advancing speed and peripheral speed.

Adopting the electronic control unit allows all speeds to be inputted in a simple manner before each application and/or these speeds to be controlled and adjusted during said application.

Preferably, the apparatus further comprises a presser device facing the moving surface of the conveyor and having a side surface to be engaged with the continuous elongated element.

The presser device keeps a contact between the continuous elongated element and the moving surface and ensures that the conveyor's speed be imparted to the continuous elongated element.

In a preferred embodiment, the presser device comprises a roller carrying the side surface and a presser element operatively acting on the roller, to press said side surface against the continuous elongated element.

In addition, preferably, the presser element is of the elastic type. This structure is simple, efficient, reliable and inexpensive.

Preferably, the presser device is positioned at a distal end of the conveyor adjacent to the extruder. In this way, the continuous elongated element is immediately brought into contact with the moving surface which is utilised over the whole extension thereof.

According to a preferred embodiment, the conveyor comprises a conveyor belt wrapped on rollers and having a going stretch defining the moving surface.

Preferably the conveyor belt is wrapped on a proximal roller located at the proximal end of the conveyor.

In addition, the conveyor belt is wrapped on a distal roller located at a distal end of the conveyor adjacent to the extruder.

More preferably, the going stretch is rectilinear and the moving surface lies in a single plane.

This structure is simple, efficient, reliable and inexpensive.

Preferably, said at least one application device comprises at least one application member operatively supported relative to the conveyor and acting in thrust relationship towards the forming support.

In addition, preferably, the extruder comprises a cylinder having a delivery opening and a rotating screw housed in the cylinder and having an end close to said delivery opening.

Preferably, the extruder comprises a gear pump interposed between the rotating screw and the delivery opening.

Between the end of the rotating screw and the delivery opening or between the gear pump and said delivery opening there is no duct adapted to direct the blend away from the extruder. Therefore damages to the blend and the continuous elongated element thus produced due to the high temperatures and pressures inside the duct are avoided, which temperatures and pressures are required for keeping the blend to the fluid state. Therefore, generation of local scorches on the elastomeric material may occur within the duct, due to friction and induced heating, which local scorches lead to localised vulcanisation and impair the quality of the continuous elongated element. The vulcanised blend can in addition adhere to the duct walls, causing a reduction in the passage section of the duct itself, thus increasing pressure and temperature inside the latter, triggering a cycle making worse the features of the blend forming the continuous elongated element.

In accordance with a preferred embodiment, said forming support is a toroidal support.

Preferably, the radially external surface of said toroidal support is shaped according to the radially internal surface of the tyre to be built. After application of the continuous elongated element, the formed component therefore already has the substantially final shape of the tyre.

In accordance with an alternative embodiment of the apparatus, said forming support is a cylindrical drum. After application of the continuous elongated element, the formed component must be therefore submitted to a shaping operation adapted to give the carcass ply or plies a toroidal configuration.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the drawings, a plant for producing tyres comprising a building apparatus2in accordance with the present invention has been generally denoted at1.

Plant1is intended for manufacturing tyres3(FIG. 4) essentially comprising at least one carcass ply4preferably internally coated with a layer of airtight elastomeric material referred to as “liner”5, two so-called “beads”6integrating respective annular anchoring structures7possibly associated with elastomeric fillers7aand in engagement with the circumferential edges of the carcass ply4, a belt structure8applied at a radially external position to the carcass ply4, a tread band9applied at a radially external position to the belt structure8, in a so-called crown region of tyre3, and two sidewalls10applied at laterally opposite positions to the carcass ply4, each at a side region of tyre3, extending from the corresponding bead6to the corresponding side edge of the tread band9.

In run flat tyres or tyres intended for particular uses, auxiliary support inserts (not shown) can be also provided, of the type usually referred to as “sidewall inserts” for example, which are applied close to the sidewalls at an axially internal position to the carcass ply4or between two paired carcass plies4, and/or at an axially external position to said at least one carcass ply4.

The building apparatus2can comprise a plurality of building stations11,12,13,14,15(FIG. 1), each for example designed to form a component of tyre3under processing directly on a forming support16preferably of toroidal conformation, and more preferably having a radially external forming surface16ashaped according to the radially internal surface of tyre3when building has been completed (FIG. 4).

Alternatively one or more components of tyre3under processing, instead of being directly made on the forming support16of toroidal conformation are provided to be obtained as semifinished products from preceding working steps and assembled to other components on said forming support16. The latter can also have a cylindrical conformation or other shape different from the previously described ones.

By way of example, shown inFIG. 1is a first station in which at least one component of elastomeric material, liner5for example, is made through winding of a continuous elongated element of elastomeric material into coils disposed mutually close and distributed along the forming surface16aof the forming support16of toroidal conformation. In at least one second building station12manufacture of one or more carcass plies4can be achieved, which are obtained by laying strip-like elements on the forming support16, in circumferentially approached relationship, which strip-like elements are formed from a continuous strip of elastomeric material cut to size comprising textile or metallic cords disposed in parallel side-by-side relationship. A third building station13can be dedicated to manufacture of the annular anchoring structures7and fillers7aintegrated into the tyre beads6, respectively obtained through laying into radially superposed coils of at least one continuous elongated element comprising at least one rubber-coated metallic cord and through winding of a continuous elongated element of elastomeric material into coils disposed close to each other and distributed along said forming surface16a. At least one fourth building station14can be dedicated to manufacture of the annular anchoring structure8, obtained for example by laying of strip-like elements in circumferentially approached relationship, which are formed from a continuous strip of elastomeric material comprising preferably metallic cords mutually parallel, and/or through winding into axially approached coils of at least one rubber-coated reinforcing cord, preferably of metal, in the crown portion of tyre3.

At least one fifth building station15can be designed for manufacture of the tread band9and sidewalls10. Tread band9and sidewalls10are preferably obtained through winding of at least one continuous elongated element of elastomeric material, into mutually approached coils.

The building stations11,12,13,14,15can simultaneously operate each on a respective tyre3being processed, carried by a respective forming support16, sequentially transferred from a building station to the subsequent building station, through robotized arms17or other suitable devices.

Tyres3built by apparatus2are sequentially transferred to at least one vulcanisation unit18integrated into plant1.

In accordance with the present invention, at least one of the components in elastomeric material of tyre3, such as liner5, fillers7aand/or other parts of elastomeric material of beads6, sidewalls10, tread band9, under-belt layer, under-layer of the tread band, abrasion-proof elements and/or others, is obtained by a forming device generally denoted at19(FIGS. 2 and 3).

The forming device19comprises at least one feeding unit20supplying a continuous elongated element21of elastomeric material (FIGS. 2 and 3).

The feeding unit20comprises an extruder22provided with a cylinder23into which elastomeric material is introduced. Cylinder23heated to a controlled temperature, just as an indication included between about 40° C. and about 120° C., operatively houses a rotating screw24, by effect of which the elastomeric material is pushed along cylinder23, towards a delivery opening25of extruder22. If required, the elastomeric material can be conveyed through a gear pump26for example, operatively interposed between the rotating screw24and the delivery opening25, to ensure more flow rate uniformity through the latter.

In more detail, a flange22ais mounted on extruder22and carries a die22bdefining said delivery opening25. Preferably, the delivery opening25is disposed close to the gear pump26or, in the absence of the latter, to an end24aof the rotating screw. In particular, distance “1” existing between said gear pump26or the end24aof the rotating screw24, and the delivery opening25, i.e. the length of duct22cbounded by die22b, is smaller than about 30 cm, preferably smaller than about 15 cm, so as to limit flowing of the blend on the duct22cwalls and thereby generation of dangerous local cross-linking of the blend. Preferably, also flange22aand die22bare thermoregulated, i.e. heated to a controlled temperature. Screw24and gear pump26too can be heated to a controlled temperature, by way of example included between about 40° C. and about 120° C.

Therefore the continuous elongated element21of raw elastomeric material having a substantially circular cross-section profile is delivered through the delivery opening25. Alternatively, conformation of the delivery opening25and, consequently, of the cross-section profile of the continuous elongated element21, can be of the ellipsoidal type. In both cases, the area of the cross section of the delivery opening25is preferably included between about 3.5 mm2and about 100 mm2.

Said dimensional features allow the continuous elongated element21to be delivered according to a desired linear delivery speed “V1”, corresponding to a so-called “target value”, of the volumetric flow rate, just as an indication included between about 1 cm3/s and about 70 cm3/s, without too many deformations being imposed to the mass of elastomeric material at the delivery opening25. Thus the temperature of the elastomeric material at the delivery opening25can be advantageously maintained to relatively low values, just as an indication included between about 70° C. and about 110° C.

An application device27operating downstream of the feeding unit20carries out application of the continuous elongated element21coming from said feeding unit20onto the forming support16(FIG. 3).

During application, the forming support16supported in overhanging for example by one of said robotized arms17, is driven in rotation at a peripheral speed “V3” by suitable devices, and moved in front of the application device27, for distributing the continuous elongated element21into coils disposed in approached and/or superposed relationship and wound around this forming support16, so as to form a liner5for example, or any other component of elastomeric material of the tyre being processed.

The application device27comprises at least one application member28acting in thrust relationship towards the forming support16, by effect of a pneumatic actuator29for example, for applying the continuous elongated element21onto the forming support16.

As shown in the drawings, the application member28is a roller mounted, preferably idly, on a rocking arm27a. The end of the rocking arm27aopposite to the end carrying roller28is connected to the pneumatic actuator29. A cylindrical side surface28aof the idler roller28rests on and pushes against the continuous elongated element21applied to the forming support16. Said cylindrical side surface28ais preferably made of a silicone-based anti-sticking material.

Operatively disposed between the feeding unit20and the application device27is a conveyor30the function of which is to bring the continuous elongated element21coming out of the feeding unit20onto the forming support16and close to the application device27. The application member28is preferably operatively supported with respect to conveyor30.

Conveyor30has a moving surface31which carries out a continuous motion along a predetermined direction “X”, at a linear advancing speed “V2” and towards a proximal end32of the conveyor30adjacent to the forming support16.

The continuous elongated element21is advanced on the moving surface31along the predetermined direction “X” and guided until the proximal end32, at which the application device27is positioned.

In the preferred embodiment shown, conveyor30comprises a conveyor belt33wrapped on a proximal roller34a, located at the proximal end32of conveyor30, and on a distal roller34b, located at the distal end35of conveyor30opposite to the proximal end32and adjacent to the delivery opening25of extruder22. One or both rollers34a,34bare power driven.

The conveyor belt33can be for instance defined by a toothed belt passing over rollers34a,34bhaving a peripheral toothing. The conveyor belt33, at least in the portion coming into contact with the continuous elongated element21, is made of a preferably silicone-based anti-sticking material.

The conveyor belt33at the upper part thereof has a rectilinear going stretch33asupporting the elongated element21and therefore defining the moving surface31which substantially lies in a single plane.

The conveyor belt33is such driven that it follows the continuous elongated element21moving away from extruder22until close to the application member28.

Conveyor30and applicator roller28can have a size in width substantially as high as that of the continuous elongated element21, so that they do not hinder movement of the forming support16by the robotized arm during laying of the continuous elongated element21. In different embodiments, the width of the conveyor belt33can vary between about 0.8 and about 3 times the width of the continuous elongated element21.

Conveyor30further comprises a presser device36mounted to the distal end35of conveyor30. In the embodiment shown, the presser device36comprises a roller37which faces the moving surface31of conveyor30and has a cylindrical side surface38susceptible of engagement with the continuous elongated element21. Roller37is freely rotatable around a rotation axis of its own substantially parallel to the rotation axes of the proximal34aand distal34brollers of conveyor30and to that of roller28of the application device27. The cylindrical side surface38of roller37too is preferably made of silicone-based anti-sticking material.

Roller37is pushed towards the moving surface31of conveyor30and pressed against the continuous elongated element21through a presser element39, of the elastic type for example, such as a spring, or of a hydraulic or pneumatic type.

In the embodiment shown, roller37is positioned immediately downstream of extruder22, so as to guide the continuous elongated element21on the conveyor belt33and keep the continuous elongated element21in contact with said conveyor belt33.

In this manner, the continuous elongated element21, at least in the region immediately downstream of the presser device36, moves together with the moving surface31and at the same linear advancing speed “V2” as the latter. The continuous elongated element21exiting extruder22is directly fed between roller37and the moving surface31without interposition of other devices adapted to modify the section of same, such as calenders, etc., for example. In fact, as shown inFIG. 3, in the region placed downstream of the delivery opening25and upstream of conveyor30no devices of the above mentioned type are present.

The forming device19further comprises an electronic control unit40operatively connected to extruder22, the devices determining rotation of support16and conveyor30. The control unit40is provided with sensors capable of detecting the operating parameters of the forming devices19, among which linear delivery speed “V1”, linear advancing speed “V2”, and peripheral speed “V3” and is able to modify one or more of these speeds before starting application and/or during an application cycle.

In use, the continuous elongated element21delivered from extruder22at the linear delivery speed “V1” is directly routed between roller37of the presser device36and belt33. Roller37presses against the continuous elongated element21that in turn presses against belt33and gives the continuous elongated element21the same linear advancing speed “V2” as that of belt33, which is different from the linear delivery speed “V1”. Preferably, the linear advancing speed “V2” is included between about 0.75 times and about 0.995 times the linear delivery speed “V1”.

In different embodiments, the linear advancing speed “V2” is included between about 1.005 times and about 1.5 times the linear delivery speed “V1”.

If the linear advancing speed “V2” is higher than the linear delivery speed “V1”, the continuous elongated element21is axially drawn, close to roller37. The ratio of the area of the cross-section of the continuous elongated element21downstream of roller37to the area of the cross-section of the continuous elongated element21upstream of roller37that is substantially coincident with that of the delivery opening25, is preferably included between about 0.7 and about 0.99.

If the linear advancing speed “V2” is lower than the linear delivery speed “V1”, the continuous elongated element21is axially compressed, close to roller37. The ratio between the area of the cross-section of the continuous elongated element21downstream of roller37and the area of the cross-section of the continuous elongated element21upstream of roller37that is substantially coincident with that of the delivery opening25, is preferably included between about 1.01 and about 1.3.

Once the continuous elongated element21has reached the proximal end32, it leaves conveyor30and is applied to the forming support16passing between the support16itself and the application member28.

The application member28presses against the continuous elongated element21that in turn presses against the forming support16and gives the continuous elongated element21the peripheral speed “V3” of the forming support16which is higher than the linear delivery speed “V1”.

Preferably, the peripheral speed “V3” is included between about 1.2 times and about 7 times the linear delivery speed “V1”, more preferably is included between about 1.3 times and about 1.6 times the linear delivery speed “V1.”.

Preferably, in addition, the peripheral speed “V3” is higher than the linear advancing speed “V2” and the continuous elongated element21is therefore preferably drawn in the length included between the presser device36and the application member27.

In these embodiments, the continuous elongated element21through the two quick speed changes is in any case axially drawn as compared with when it exits the extruder22.

The ratio between the area of the cross-section of the continuous elongated element21once laid on the forming support16and the area of the cross-section of the continuous elongated element21coming out of extruder22, which is substantially coincident with that of the delivery opening25, is preferably higher than or as high as about 0.3 and lower than 1. Since the first quick speed change can involve drawing or compression, axial drawing can take place both at the presser device36and at the application member28or fully at the application member28.

Alternatively, in different embodiments the peripheral speed “V3” can be lower than the linear delivery speed “V1”, so as to compress the continuous elongated element21. This solution is adopted with particular elastomeric materials or geometry of a tyre component such as to require winding of coils with a continuous elongated element21having greater section than the section of the delivery opening25.

In these cases too it is possible to have said speed reduction with consequent compression and increase in the section area in two distinct steps even if “V2” is lower than “V1”, or it is possible to have a step of speed reduction and consequent compression preceded by a step of speed increase and consequent drawing (or stretching), when “V2” is higher than “V1”.

Preferably, in the last-mentioned embodiments, the peripheral speed “V3” is included between about 0.5 times and about 0.95 times the linear delivery speed “V1”. More preferably, the peripheral speed “V3” is included between about 0.65 times and about 0.85 times the linear delivery speed “V1”.

The ratio between the area of the cross-section of the continuous elongated element21once laid on the forming support16and the area of the cross-section of the continuous elongated element21coming out of extruder22, that is substantially coincident with that of the delivery opening25, is preferably smaller than or as high as about 1.5 and greater than 1.

The ratio between the linear advancing speed “V2” and the linear delivery speed “V1” and the ratio between the peripheral speed “V3” and the linear delivery speed “V1” can be inputted before starting laying and maintained constant during application or varied, even in a manner independent of each other, during the application itself, to change the features of the continuous elongated element21, based on the laying regions on the forming support16. This form of laying is particularly advantageous above all if said forming support16is of toroidal conformation due to the particular geometry of the components to be built when building takes place on an already “shaped” profile.

At the end of application, the continuous elongated element21is cut at a region included between extruder22and conveyor30, preferably this region being close to the delivery opening25, and the length of continuous elongated element21disposed downstream of the cutting point is fully applied to the forming support16.