Process for making tyres for vehicle wheels

Abstract

A tyre (1) is built on a toroidal support (8) and subsequently closed in a moulding cavity (14) defining a moulding surface (14a) directed towards the tyre (1). The tyre (1) is expanded from a building condition wherein it has an internal surface (1a) adherent against the toroidal support (8) to a pressing condition, wherein the tyre (1) is vulcanised with an external surface (1b) thereof pressed against the moulding surface (14a) due to an expansion imparted to the tyre (1). In the pressing condition, the expansion imparted in the shoulder zones (Sz) of the tyre is smaller than the expansion imparted in each of the sidewall zones (Fz) and crown zone (Cz).

Description

[0001] PROCESS FOR MAKING TYRES FOR VEHICLE WHEELS

[0002] The present invention relates to a process for making tyres for vehicle wheels.

[0003] In the tyre production cycle, it is provided that, following a building process in which the various components of the tyre itself are made and assembled, a moulding and vulcanisation process is actuated that is aimed to stabilise the structure of the tyre according to a desired geometric shape, normally characterised by a particular tread design.

[0004] For such purpose, the tyre is introduced in a vulcanisation mould normally comprising a pair of axially adjoining sidewall plates, arranged to operate on the bead and on the sidewalls of the tyre, and at least one crown of sectors, distributed circumferentially and radially approachable for operating at the tread band of the tyre. More particularly, the sidewall plates and the sectors are mutually movable between an open condition, in which they are spaced in order to allow the operation of loading the tyres being processed, and a closed condition in which they define a moulding cavity shaped according to the geometric configuration of the external surfaces of the tyre to be obtained. The terms "axial", "axially", "radial", and "radially" are used with reference to the tyre or to a vulcanisation mould used in the process for producing the tyre.

[0005] In particular, with the terms "axial" and "axially", it is intended references / sizes arranged / measured or extended in a direction substantially parallel to the rotation axis of the tyre or of the vulcanisation mould. Preferably, by "axial direction" it is intended a direction parallel to the rotation axis of the tyre or at most tilted by 5° with respect thereto.

[0006] With the terms "radial" and "radially", it is intended references / sizes arranged / measured or extended in a direction perpendicular to the rotation axis of the tyre or of the vulcanization mould and lying in a plane comprising such rotation axis.

[0007] Moulding methods are known in which, within the tyre, a rigid toroidal support is arranged, shaped according to the configuration of the internal surface of the tyre to be obtained. One such method is for example described in the document US 4,895,692 in which a rigid toroidal support is used in order to impart the definitive shape and size of the tyre closed in the mould. According to what described in such patent, the different heat expansion coefficient between the toroidal metallic support and the green elastomeric material with which the tyre is constituted is exploited in order to attain a suitable moulding pressure.

[0008] The document EP 0976533 on behalf of the same Applicant proposes a method and an apparatus in which the green tyre built on a toroidal support is closed in a vulcanisation mould; subsequently, vapor or another fluid under pressure is introduced in at least one fluid diffusion interspace, created between the external surface of the toroidal support and the internal surface of the tyre.

[0009] Also in the document EP 1 038 657 it is provided that pressing occurs simultaneously with an expansion imparted to the tyre by introduction of a fluid under pressure in the aforesaid interspace. At the same time as the expansion of the tyre, inner circumferential edges thereof are substantially disengaged form the toroidal support and left free to be moved, in a controlled manner, with respect to the same.

[0010] In the document WO 01 / 00395 a process is proposed in which, during the pressing executed simultaneously with the expansion imparted to the tyre, the lateral portions of the latter, for example comprised between the beads and the transition zones between the sidewalls and the tread band, are firmly retained between the inner walls of the moulding cavity and the external surface of the toroidal support.

[0011] In the document WO 2004 / 045838, the tyre arranged on the toroidal support is subjected to a pressing against the same heated toroidal support, in order to determine a partial vulcanisation of the more internal layer and of the beads of the tyre, before being pressed against the inner walls of the mould by introduction of the operating fluid in the diffusion interspace. The Applicant has observed that in the known moulding and vulcanisation processes which employ the aforesaid toroidal support, it might be difficult to execute a suitable control of the deformations induced at the components of the tyre during the expansion imparted by introduction of the operating fluid under pressure in the diffusion interspace. Indeed, also due to the high plasticity of the still-green elastomeric material, some structural reinforcement components can undergo undesired movements within the elastomeric mass, with consequent geometric alterations and, in extreme cases, functional alterations. In particular, the Applicant has encountered that in some circumstances the expansion of the tyre can generate, above all in the shoulder zones where the transition between the tread band and the sidewalls occurs, localised structural defects e.g. represented by undesired shiftings of the end portions of the belt layers, and / or by aesthetic irregularities on the external surfaces of the finished tyre.

[0012] The Applicant has nevertheless perceived that an accurate management of the deformations sustained in different zones of the green tyre, simultaneously with the expansion induced during pressing, enables an improved control of the deformations and of the relative positioning between the single components of the tyre, more precisely the Applicant has perceived that such management of the deformations results more effective by containing the deformations in the shoulder zone.

[0013] The Applicant has finally found that, for the benefit of a geometric and structural repeatability of the obtained tyres and of a consequent waste reduction, it is convenient that the expansion of the tyre is supported in the crown zone and in the sidewall zones, while the expansion imparted to the shoulder zones is contained at lower size value.

[0014] More particularly, forming the object the present invention is a process for making tyres for vehicle wheels.

[0015] Preferably, provision is made for building a tyre on a toroidal support externally having a forming surface.

[0016] Preferably, provision is made for closing the toroidal support carrying the tyre within a moulding cavity defining a moulding surface directed towards the tyre.

[0017] Preferably, provision is made for expanding the tyre from a building condition in which it has an internal surface adherent against said forming surface and an external surface at least partly spaced from the moulding surface, to a pressing condition, in which an external surface of the tyre is pressed against the moulding surface due to an expansion imparted to the tyre.

[0018] Preferably, provision is made for vulcanising the tyre in the pressing condition.

[0019] Preferably, in the pressing condition, the internal surface of the tyre has:

[0020] a crown zone, placed at a tread band of the tyre, spaced from the forming surface;

[0021] two sidewall zones, each placed at un respective sidewall of the tyre, spaced from the forming surface;

[0022] two shoulder zones, each interposed between the crown zone and one of the sidewall zones and spaced from the forming surface.

[0023] Preferably, the expansion imparted in the shoulder zones is smaller than the expansion imparted in each of said sidewall zones and crown zone.

[0024] The Applicant deems that the containment of the expansion in the shoulder zones to the benefit of the expansion in the crown zone and in proximity to the sidewalls allows preserving the structural integrity of the tyre itself in the zones most exposed to the onset of aesthetic and / or structural defects. Hence appreciable advantages are attained in terms of process repeatability and reduction of the processing waste.

[0025] The reduced exposure to deformations and structural defects also enables reducing the thicknesses of the components in proximity to the shoulder zones and in the neighbouring areas, attaining various advantages in terms of weight reduction and rolling resistance, with an increase of the structural strength of the tyre at high operating speeds, and an improvement of the performance behaviour.

[0026] In at least one convenient embodiment, the invention also comprises one or more of the following preferred characteristics. Preferably, in the pressing condition, said internal surface of each shoulder zone is spaced from the forming surface to a smaller extent than a maximum distance lying between the forming surface and each of said sidewall zones.

[0027] Preferably, in the pressing condition said internal surface of each shoulder zone is spaced from the forming surface to a smaller extent than a distance lying between the forming surface and the crown zone.

[0028] Preferably, said crown zone is axially delimited between axially opposite edges of a belt structure of the tyre.

[0029] Preferably, each of the sidewall zones is radially extended away from a respective bead of the tyre, passing through a maximum chord point of the latter up to a transition point in which an axial size of the tyre is comprised between 82% and 97% of a maximum chord.

[0030] Preferably, each of the shoulder zones is delimited between the crown zone and one of the sidewall zones.

[0031] Preferably, each shoulder zone is extended starting from a respective axial edge of a belt structure of the tyre up to a transition point in which an axial size of the tyre is comprised between 82% and 97% of a maximum chord.

[0032] Preferably, in the pressing condition, an interspace is formed between the internal surface of the tyre and said forming surface.

[0033] Preferably, said interspace is extended along the extension of the sidewall zones, of the shoulder zones and of the crown zone.

[0034] Preferably, said interspace is extended without axial and radial interruptions.

[0035] Preferably, in the crown zone, the interspace has a substantially axial extension.

[0036] Preferably, in the sidewall zones, the interspace has a mainly radial extension.

[0037] Preferably, in the shoulder zones, the interspace has a variable extension from mainly axial in proximity to the crown zone, to mainly radial in proximity to the sidewall zones.

[0038] Preferably the tyre, before being expanded in the pressing condition, is subjected to centripetal pressing against said forming surface.

[0039] Preferably the tyre, before being expanded in the pressing condition, is subjected to pre-vulcanisation of the internal surface of the tyre by administration of heat through the forming surface.

[0040] Preferably, expanding the tyre is executed by introduction of a primary fluid between the forming surface and the internal surface of the tyre.

[0041] Preferably, the primary fluid is heated to a first operating temperature, in order to determine the vulcanisation of the tyre. Preferably, said centripetal pressing is executed by introduction of a secondary fluid under pressure in the moulding cavity.

[0042] Preferably, the administration of heat during the centripetal pressing is executed by introduction of said primary fluid, heated to a second operating temperature, within the toroidal support. Preferably, during the centripetal pressing, the primary fluid is introduced at a pressure lower than a feed pressure of the secondary fluid.

[0043] Further characteristics and advantages will be clearer from the detailed description of preferred but not exclusive embodiments of a process for making tyres for vehicle wheels, 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:

[0044] - figure 1 shows, in partial radial section, a tyre built on a toroidal forming support and inserted in a vulcanisation mould;

[0045] - figure 2 shows the tyre of figure 1 in a pressing condition within the vulcanisation mould;

[0046] - figure 3 shows an enlarged detail of figure 2;

[0047] - figure 4 shows, in radial section, a tyre obtainable by the present process.

[0048] The process according to the present invention is aimed for attaining tyres for vehicle wheels, of the type better represented in figure 4 and overall indicated with 1.

[0049] For the purpose of the present description, it is intended by "geometric rotation axis" (not visible in the drawings) the rotation axis of the tyre 1 in operating conditions. 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 tyre (i.e. to a direction perpendicular to the geometric rotation axis of the tyre 1) and to the axial direction of the tyre 1 (i.e. to a direction parallel to the geometric rotation axis of the tyre 1). The tyre 1 comprises at least one carcass ply 2 preferably internally coated with a layer of impermeable elastomeric material or so-called liner 3 and having respective end flaps fixed at so-called beads 4 defined along radially inner edges, at which there is usually the engagement between the tyre 1 and a respective mounting rim (not depicted).

[0050] In radially outer position with respect to the carcass ply / plies 2, one or more belt layers 5a is circumferentially engaged with the belt structure 5. A tread band 6 is radially superimposed on the belt structure 5.

[0051] The tyre 1 also comprises a pair or sidewalls 7, applied in laterally opposite positions on the carcass ply / plies 2 and extended in substantially radial direction, each from the corresponding bead 4 towards a corresponding axial edge of the tread band 6.

[0052] The building of the tyre 1 provides that the components thereof be assembled on a dismountable rigid toroidal support 8, externally having a forming surface 8a with toroidal shape, substantially coinciding with that of an internal surface la of the tyre 1, e.g. according to that described in EP 0976535A2, on behalf of the same Applicant.

[0053] The green tyre 1 thus built is transferred, together with the toroidal support 8, into a vulcanisation mould 11 associated with a vulcanisation press, not illustrated since it is attainable in any manner that is convenient to the man skilled in the art.

[0054] For example, the vulcanisation mould 11 can be composed of a lower half-part and an upper half-part respectively engaged with a base and with a closure portion of the press. In the enclosed drawings, a portion of only one of the half-parts of the mould is schematically illustrated, the remaining portion being arranged mirror with respect to that represented, around the geometric rotation axis of the tyre. The other half-part is in turn arranged symmetrically to that partially represented, with respect to an axial centreline plane perpendicular to the geometric rotation axis.

[0055] In the embodiment illustrated as an example, each of the lower and upper half-parts of the vulcanisation mould 11 has a so-called sidewall plate 12 and a crown of sectors 13. The lower and upper half-parts are mutually movable between an open condition in which they are mutually spaced in order to allow the insertion and the extraction of the tyre 1 together with the toroidal support 8, and a closed position, in which they are mutually adjoining in order to close the green tyre 1 borne by the toroidal support 8 within a moulding cavity 14. The moulding cavity 14 defines a moulding surface 14a directed towards the tyre 1 and reproducing, in negative, the geometric shape of the external surface lb of the finished tyre 1. In particular, it is preferably provided that the sidewall plates 12 define the moulding surface 14a at the beads and sidewalls 7, while the sectors 13 define the moulding surface 14a at the tread band 6. On such matter, the sectors 13 may have ribs and / or slots 13a prearranged for forming a so-called tread design on the tread band 6 of the finished tyre 1. The sidewall plates 12 can in turn have writings, or other indicative signs, which remain impressed on the sidewalls 7 of the finished tyre 1.

[0056] As is visible in figure 1, when is closed in the vulcanisation mould 11 the green tyre 1 is situated in a building condition in which its internal surface la adheres against the forming surface 8a of the toroidal support 8, while the external surface lb of the same tyre 1 is spaced from the moulding surface 14a for the entire or nearly entire extension thereof. More particularly, with the closure of the vulcanisation mould 11 the beads of the tyre 1 are preferably clamped in the absence of clearance between the sidewall plates 12 and respective radially inner portions of the toroidal support 8 so as to obtain, at the same beads, a moulding action of so-called "volume" type. In proximity to the sidewalls 7 and the tread band 6, the external surface lb of the green tyre 1 instead remains spaced from the moulding surface 14a, except for a few localized contacts that might occur in proximity to the aforesaid ribs 13a projecting towards the interior of the moulding cavity 14.

[0057] The green tyre 1 closed in the moulding cavity 14 is suitable for being subjected to a possible treatment of centripetal pressing against the forming surface 8a, and simultaneous administration of heat, preferably through the latter. This centripetal pressing treatment is suitable for determine a pre-vulcanisation of the liner 3 and / or, more generally, of the internal surface la of the tyre 1 itself. The centripetal pressing can be obtained by introduction of a secondary fluid under pressure within the moulding cavity 14, between the external surface lb of the green tyre 1 and the moulding surface 14a. The secondary fluid can for example consist of air, nitrogen or another insert gas, fed at a pressure approximately comprised between 0.8 and 1.8 Mpa.

[0058] The administration of heat during the treatment of centripetal pressing can be obtained by introducing, within the toroidal support 8, a primary fluid, e.g. vapor or nitrogen, heated to a second operating temperature and preferably at a prevulcanisation pressure lower than the secondary fluid feed pressure.

[0059] The centripetal pressing treatment is actuated for a time sufficient to ensure that the liner 3 and / or other elastomeric components arranged at the internal surface la of the tyre 1 reach a desired crosslinking degree, preferably in concomitance with a partial pre-vulcanisation of the beads 4 clamped between the moulding surface 14a and the forming surface 8a of the toroidal support 8.

[0060] Once the centripetal pressing treatment is completed, the secondary fluid is evacuated from the moulding cavity 14 and the green tyre 1, still closed in the same moulding cavity, is ready to be expanded from the aforesaid building condition to a pressing condition. In such pressing condition, an external surface lb of the tyre 1, due to the expansion imposed thereto, is pressed against the moulding surface 14a.

[0061] The expansion of the tyre 1 can be assisted by the introduction of the same primary fluid, brought to a vulcanisation pressure and heated to a first operating temperature greater than the prevulcanisation pressure and second operating temperature employed during the preceding centripetal pressing. The primary fluid introduced in the toroidal support 8 is in fact able to reach the internal surface la of the tyre 1 through suitable passages prearranged in the toroidal support itself, determining the expansion of the tyre 1 so as to form and fill an interspace 15 created between the internal surface la of the latter and the forming surface 8a.

[0062] The pressing condition is maintained for a predetermined time, suitable for determining a correct vulcanisation of the tyre 1, before evacuating the primary fluid from the vulcanisation mould 11 in order to allow the opening thereof and allow the extraction of the vulcanised tyre 1.

[0063] Further details on the modes of execution of the centripetal pressing treatment and subsequent expansion in the pressing condition are derivable from the abovementioned document WO 2004 / 045838 on behalf of the same Applicant.

[0064] As is visible in figure 2, when the tyre 1 is closed in the vulcanisation mould 11 in the pressing condition, the size and shape of the interspace 15 defined between the toroidal support 8 and the internal surface la of the tyre 1 is conditioned by the freedom of movement of the same tyre 1 within the moulding cavity 14, upon effect of the push produced by the pressure of the primary fluid. This freedom of movement is in turn conditioned by the geometric and size characteristics of the toroidal support 8 with respect to that of the moulding surface 14a. It follows that by suitably selecting, during design phase, the geometric and size characteristics of the toroidal support 8 with respect to that of the moulding surface 14a, it is possible to determine the shape of the interspace 15 and the consequent stresses imparted to different zones of the tyre 1 during the expansion imparted thereto in order to reach the pressing condition.

[0065] On such matter, it is provided that on the internal surface la of the tyre 1, the following can be identified: a crown zone Cz, close to the tread band 6, two sidewall zones Fz, each close to one of the sidewalls 7, and two shoulder zones Sz, each interposed between the crown zone Cz and one of the sidewall zones Fz.

[0066] More particularly, as better illustrated in figure 4 the crown zone Cz is axially delimited between axially opposite edges of the belt structure 5 - that is between axial geometric planes that contain the same axially opposite edges.

[0067] Each of the sidewall zones Fz is radially extended away from the respective bead 4 passing through a maximum chord point Pw of the tyre 1 up to a transition point Pt in which the axial size Wt of the tyre 1 is comprised between 82% and 97% of a maximum chord Wmax.

[0068] By "maximum chord" Wmax it is intended the axial size of the tyre 1 measured at its widest point parallel to the geometric rotation axis.

[0069] Each of the shoulder zones Sz is delimited between the crown zone Cz and one of the sidewall zones Fz, and is extended starting from the respective axial edge of the belt structure 5 -that is from the axial geometric plane that contains it - up to said transition point Pt.

[0070] The interspace 15 is extended, preferably without axial interruptions, along the extension of the sidewall zones Fz, of the shoulder zones Sz and of the crown zone Cz. In the crown zone Cz, the interspace 15 has an extension that is substantially axial. In the sidewall zones Fz, the interspace 15 has a mainly radial extension. In the shoulder zones Sz, the interspace 15 has a variable extension from mainly axial in proximity to the crown zone Cz, to mainly radial in proximity to the sidewall zones Fz. In the pressing condition, the internal surface la of the tyre 1 is spaced from the forming surface 8a at the crown zone Cz, the sidewall zones Fz and the shoulder zones Sz.

[0071] The shape of the toroidal support 8 and of the moulding surface 14a is conveniently selected in a manner such that, in the pressing condition, the expansion imparted in the shoulder zones Sz is lower than the expansion imparted in each of the sidewall zones Fz and crown zone Cz. Consequently, in the pressing condition, each shoulder zone Sz is spaced from the forming surface 8a according to a size DSz (figure 3) smaller than a maximum distance DFz lying between the forming surface 8a and each of said sidewall zones Fz, as well as smaller than a distance DCz lying between the forming surface 8a and the crown zone Cz.

[0072] This circumstance facilitates an effective tensioning of the carcass ply 2 and of the belt structure 5 together with the action of pressing the sidewalls 7 and the tread band 6 against the moulding surface 14a, simultaneously with a suitable containment of the expansion imparted in proximity to the shoulder zones Sz. The reduced mobility of the shoulder zones Sz therefore allows overcoming potential critical issues connected to a difficult control of the movements of the elastomers still in the plastic state, offering a greater repeatability of results and a reduction of the processing discards. Overcoming these critical issues also makes it possible to reduce, at the shoulder zones Sz, the quantity of additional elastomeric material which in the prior art might have been necessary for mitigating the encountered process criticalities. At the same time, the continuity of the interspace 15 lacks interruptions between the crown zone Cz and the sidewall zones Fz allows an efficient diffusion of the primary fluid in the interspace 15 and, therefore, a correct distribution of the pressure and heat on the entire internal surface la of the tyre being processed.

[0073] At the end of the vulcanisation cycle, the primary fluid is evacuated from the vulcanisation mould 11 and the latter can be opened by separation of the aforesaid half-parts, in order to allow the extraction of the vulcanised tyre 1 and its subsequent separation from the toroidal support 8.

Claims

CLAIMS1. Process for making tyres for vehicle wheels, comprising: building a tyre (1) on a toroidal support (8) externally having a forming surface (8a);closing the toroidal support (8) carrying the tyre (1) within a moulding cavity (14) defining a moulding surface (14a) directed towards the tyre (1);expanding the tyre (1) from a building condition in which it has an internal surface (la) adherent against said forming surface (8a) and an external surface (lb) at least partly spaced from the moulding surface (14a), to a pressing condition, wherein an external surface (lb) of the tyre (1) is pressed against the moulding surface (14a) due to an expansion imparted to the tyre (1);vulcanising the tyre (1) in the pressing condition; wherein in the pressing condition, the internal surface (la) of the tyre (1) has:a crown zone (Cz), placed at a tread band (6) of the tyre (1), spaced from the forming surface (8a);two sidewall zones (Fz), each placed at a respective sidewall (7) of the tyre (1), spaced from the forming surface (8a);two shoulder zones (Sz), each interposed between the crown zone (Cz) and one of the sidewall zones (Fz) and spaced from the forming surface (8a);wherein the expansion imparted in the shoulder zones (Sz) is smaller than the expansion imparted in each of said sidewall zones (Fz) and crown zone (Cz).

2. Process according to claim 1, wherein in the pressing condition, said internal surface in each shoulder zone (Sz) is spaced from the forming surface (8a) to a smaller extent than the maximum distance lying between the forming surface (8a) and each of said sidewall zones (Fz).

3. Process according to claim 1 or 2, wherein in the pressing condition, said internal surface in each shoulder zone (Sz) is spaced from the forming surface (8a) to a smaller extent than the distance lying between the forming surface (8a) and the crown zone (Cz).

4. Process according to one or more of the preceding claims, wherein said crown zone (Cz) is axially delimited between axially opposite edges of a belt structure (5) of the tyre (1).

5. Process according to one or more of the preceding claims, wherein each of the sidewall zones (Fz) is radially extended away from a respective bead (4) of the tyre (1), passing through a maximum chord point (Pw) of the latter up to a transition point (Pt) wherein an axial size (Wt) of the tyre (1) is comprised between 82% and 97% of a maximum chord (Wmax).

6. Process according to one or more of the preceding claims, wherein each of the shoulder zones (Sz) is delimited between the crown zone (Cz) and one of the sidewall zones (Fz).

7. Process according to one or more of the preceding claims, wherein each shoulder zone (Sz) is extended starting from a respective axial edge of a belt structure (5) of the tyre (1) up to a transition point (Pt) wherein an axial size (Wt) of the tyre (1) is comprised between 82% and 97% of a maximum chord (Wmax).

8. Process according to one or more of the preceding claims, wherein in the pressing condition, an interspace (15) is formed between the internal surface (la) of the tyre (1) and said forming surface (8a).

9. Process according to claim 8, wherein said interspace (15) is extended along the extension of the sidewall zones (Fz), of the shoulder zones (Sz) and of the crown zone (Cz).

10. Process according to claim 8 or 9, wherein said interspace (15) is extended without axial and radial interruptions.

11. Process according to one or more of the claims from 8 a 10, wherein in the crown zone (Cz), the interspace (15) has an axial extension.

12. Process according to one or more of the claims from 8 to 11, wherein in the sidewall zones (Fz), the interspace (15) has a mainly radial extension.

13. Process according to one or more of the claims from 8to 12, wherein in the shoulder zones (Sz), the interspace (15) has a variable extension from mainly axial in proximity to the crown zone (Cz), to mainly radial in proximity to the sidewall zones (Fz).

14. Process according to one or more of the preceding claims, wherein the tyre (1), before being expanded in the pressing condition, is subjected to:centripetal pressing against said forming surface (8a); pre-vulcanisation of the internal surface (la) of the tyre (1) by administration of heat through the forming surface (8a).

15. Process according to one or more of the preceding claims, wherein expanding the tyre (1) is executed by introduction of a primary fluid between the forming surface (8a) and the internal surface (la) of the tyre (1).

16. Process according to claim 15, wherein the primary fluid is heated to a first operating temperature, in order to determine the vulcanisation of the tyre (1).

17. Process according to one or more of the preceding claims, wherein said centripetal pressing is executed by introduction of a secondary fluid under pressure into the moulding cavity (14).

18. Process according to one or more of the claims from 15 to 17, wherein the administration of heat during the centripetal pressing is executed by introduction of said primary fluid, heatedto a second operating temperature, within the toroidal support (8).

19. Process according to claim 15 and one or more of the claims 17 or 18, wherein during the centripetal pressing, the primary fluid is introduced at a pressure lower than a secondary fluid supply pressure.

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