Curing mould and method for curing a green tyre

Abstract

The invention relates to a curing mould (10) for a tyre, comprising: an upper shell (16a) for moulding a tyre sidewall, a lower shell (16b) for moulding a tyre sidewall, - a ring of circumferential segments (20) for moulding a tyre tread, each segment comprising an upper segment part (20a) able to be separated axially from a lower segment part (20b), the curing mould being able to cooperate with - means for actuating all the segment parts to move radially simultaneously. Each lower segment part (20b) comprises a retaining device (100) for retaining the lower segment part (20b) in a radial position between a closed position of the mould and an open position thereof, the elements of the retaining device (100) belonging to the lower segment part and to the lower shell (16b).

Description

COOKING MOLD AND METHOD FOR COOKING A TIRE BLANK

[0001] The invention relates to the manufacture of tires and in particular to the molds and methods for curing or vulcanizing the tire blank. It relates in particular to the manufacture of tires having tread patterns that extend over the sidewalls, such as those used for all-terrain (or off-road) vehicles.

[0002] The manufacture of a tire comprises a curing step during which a raw tire blank is vulcanized and molded in order to obtain a tire with the desired mechanical characteristics, geometry and appearance. Curing is carried out in a tire curing mold comprising upper and lower molding assemblies, axially movable relative to each other. The molding assemblies comprise molding elements together defining an internal molding surface of the tire. Thus, a mold mainly comprises two molding shells for the tire sidewalls and two molding rings for the tire beads which are located axially on either side of a crown comprising several circumferential molding sectors for the tire tread.Such a curing mold is arranged within a curing press comprising, among other things, mechanisms for opening and closing the curing mold on a tire blank and for opening it in order to extract the vulcanized tire and introduce a new blank.

[0003] Document WO 2014 / 044713 in the name of the applicant describes such a tire curing mold mainly comprising an upper shell for molding the sidewalls of a tire which is movable with the upper platen of the press, a lower shell for molding the sidewalls of the tire which is fixed and supported by the lower platen of the press. The mold also comprises a ring of circumferential sectors for molding the tread of the tire which are radially movable between an open position and a closed position of the mold. Each sector is connected to the upper platen of the press on which the upper shell is fixed so as to be able to move axially with it while having the possibility of a displacement radial relative to it. Each sector is thus movable with radial sliding relative to the upper shell and movable with axial and radial sliding relative to the lower shell. Working satisfactorily, it turned out that such a mold was not suitable for molding tires whose tread patterns extend onto the sidewalls, because the radial retraction of the sectors of such a mold is not sufficiently great to be able to extract the vulcanized tire.

[0004] Document KR20140018710A also discloses a curing mold whose kinematics are similar to those described in the previous document, but whose ring of circumferential sectors has been divided into two parts, upper and lower, using a horizontal plane passing through the meridian of the tire in order to facilitate the introduction of the blank before curing and the extraction of the cured tire. The two rings of sectors are driven in a radial recoil movement when an actuator drives the upper shell in axial translation, but only the upper ring of sectors rises with the upper shell, the lower ring of sectors remains in contact with the lower shell. A guide finger, which protrudes at the radial interface of each upper sector in the open position of the mold, cooperates with an orifice of the lower sector opposite when the mold is closed.The guide finger pushes a spring rod located in the lower sector opposite, a rod which is intended to ensure the radial translational guidance of the lower sector. While it certainly allows for greater radial recoil than the sectors in the previous document, modifications must be made to the baking press, more particularly to its lower plate or to the mold actuation tooling, so that they can receive the mold according to this document.

[0005] However, the need to be able to use the same baking press and the same mold actuation tool, without modifications, for different types of tires, with different types of treads, and therefore to be able to accommodate different baking molds remains present.

[0006] One objective of the invention is to overcome the drawbacks of the aforementioned documents and thus to facilitate the molding and demolding of tires whose tread patterns extend onto the sidewalls. Another objective of the invention is to improve the appearance of the molded tire.

[0007] This objective is achieved by the invention which proposes a tire curing mold comprising: an upper shell for molding a tire sidewall, a lower shell for molding a tire sidewall, - a crown of circumferential sectors for molding a tire tread, each sector comprising an upper sector part capable of being separated axially from a lower sector part, the baking mold being capable of cooperating with - means for actuating in a radial movement of all the parts of sectors simultaneously and in an axial movement of the upper part of each sector relative to the lower part of the same sector during the operations of opening and closing the mold, characterized in that each lower part of the sector comprises a device for holding in radial position the lower part of the sector between a closed position of the mold and an open position thereof, the elements of the holding device belonging to the lower part of the sector and to the lower shell.

[0008] The curing mold of the invention comprises a crown of circumferential sectors which forms a closed ring in the closed position of the mold, the crown of circumferential sectors being cut along a horizontal radial plane so that the upper and lower parts of the sectors of the crown can separate from each other axially and circumferentially when the mold is opened. This already allows a larger opening of the molding cavity, which makes it easier to extract a tire whose tread patterns extend onto the sidewalls.

[0009] The invention proposes a device made in such a way as to allow the lower part of each sector to be held in radial position in order to limit the risks of relative movement between the upper and lower parts of the sectors during their closing and opening movements of the mold. In addition, such a device for holding the lower part of the sector in position prevents any movement of the latter which may occur accidentally when the mold is open (for example the fall of an object, the intervention of an operator in a press, etc.). The lower part of the sector is therefore held in position radially and can cooperate correctly with the upper part of the sector during their movements in opening and closing the mold. By holding the lower part of the sector in position, we understand that it is held in a stable position which it keeps until a predetermined force is applied to it, intended for it to leave this holding position.

[0010] According to the invention also, all the elements of the holding device belonging to the lower part of the sector and to the lower shell, the mold of the invention can be installed on any suitable press, without making modifications to the elements, for example the plates, of the latter.

[0011] Furthermore, since the holding device is connected to each lower part of the sector, this solution can be applied to any type of mold regardless of the number of sectors or their positioning within the mold.

[0012] The holding device may be made so as to allow the lower part of the sector to be held in an axial position. This makes it possible to maintain the lower part of the sector in a stable axial position, in addition to maintaining it in a stable radial position, in order to ensure proper operation of the mold without damaging the tire, for example when the mold is opened for the purpose of removing the baked tire and the latter tends to adhere to the walls of the baking mold.

[0013] Said holding device may comprise a slide extending in a radial direction which cooperates with a pusher made so as to exert an axial force on it during the radial movement of the lower sector part between an open position and a closed position of the mold. Thus, still according to the invention, the pusher which exerts an axial force in the direction of the slide also makes it possible to maintain the lower sector part in a stable axial position in its two limit positions: a first radially inside when the mold is closed and a second radially outside when the mold is opened.

[0014] In a first embodiment of the invention, the slide can be movable with the lower part of the sector and said pusher can be fixed on the lower shell by means of a sole.

[0015] The slide may comprise a roller which may cooperate with two notches arranged on either side of the pusher in the sole during radial movement of the lower part of the sector.

[0016] In a second embodiment of the invention, the slide can be fixed on the lower shell and the pusher can be movable with the lower sector part.

[0017] The slide may include two notches which can cooperate with a ball of the pusher during radial movement of the lower part of the sector.

[0018] Said pusher may comprise a return spring.

[0019] Said return spring can be calibrated so as to be able to maintain the lower part of the sector in a predefined position when the force exerted on the pusher is less than the force it undergoes when closing the mold.

[0020] The slide may have a dovetail-shaped section. This dovetail shape allows good guidance in radial translation and maintenance in axial position of the lower part of the sector, especially in the case of sticky composition or complex tread patterns of the tire which thus tends to adhere to the internal walls of the molding parts of the mold.

[0021] The invention also relates to a method of molding a tire using a mold comprising - an upper shell for molding a tire sidewall, a lower shell for molding a tire sidewall, - a crown of circumferential sectors for molding a tire tread, each sector comprising an upper sector part capable of being separated axially from a lower sector part, the mold being capable of cooperating with - means for actuating in a radial movement of all the parts of sectors simultaneously and in an axial movement of the upper part of each sector relative to the lower part of the same sector during the operations of opening and closing the mold, the method including a step of extracting the tire at the end of the cooking when all the sectors are moved radially outwards simultaneously and when the upper part of each sector, the lower part of the sector are moved axially upwards being caused to move from a first position of holding in position radially inward to a second position of holding radially outward.

[0022] The molding method of the invention may include a step of vacuum closing the mold followed by a step of opening the mold without radial retraction of the sectors to introduce a new tire blank into the mold.

[0023] The molding method of the invention may include a step of closing the mold axially only on the tire blank introduced inside the mold.

[0024] The invention will be better understood from the remainder of the description, which is based on the following figures: Figure 1 is a radial sectional view of a baking mold according to a first embodiment of the invention; Figure 2a is an enlarged scale radial sectional view of the lower part of the mold of Figure 1 shown in the closed position and Figure 2b is a detailed view of the device for holding the sector of Figure 2a in position, the mold being in the open position; Figures 3a to 3i are simplified radial sectional views illustrating the mold of Figure 1 in different operating positions; Figure 4 is a radial sectional view of a baking mold according to a second embodiment of the invention;Figure 5a is an enlarged scale radial sectional view of the lower part of the mold of Figure 4 shown in the closed position and Figure 5b is a detail view of the device for holding the sector of Figure 5a in position, the mold being in the open position; Figure 6 is an enlarged scale sectional view along plane AA; Figures 7a to 7i are simplified radial sectional views illustrating the mold of Figure 4 in different operating positions.;

[0025] In the various figures, identical or similar elements bear the same reference. Their description is therefore not systematically repeated.

[0026] Figure 1 illustrates a curing mold 10 of a tire blank according to a first embodiment of the invention. The curing mold 10 is intended to be inserted between the upper 2 and lower 4 plates of a curing press 1. A curing press curing comprises a frame forming a base for the mold, assumed to be stationary and fixed to the ground. The press also comprises means for guiding and actuating (for example hydraulic cylinders) the drive mechanisms in an opening and closing movement of the mold, as well as an installation for providing the mold with the curing conditions (in terms of pressure and temperature of the heat transfer fluid) necessary for vulcanizing the tire.

[0027] The curing mold 10 of a tire blank comprises an upper molding assembly and a lower molding assembly, each molding assembly comprising an upper shell 16a, respectively a lower shell 16b for molding a sidewall of the tire, and an upper ring 18a, respectively a lower ring 18b for molding a bead of the tire, as well as a ring 20 of circumferential sectors for molding the tread of the tire. In the example illustrated in the figures, the mold is of the “container” type, the upper shell 16a being caused to slide axially with the upper platen 2 of the press, the lower shell 16b being rigidly fixed to the lower platen 4 of the press, and the circumferential sectors being caused to perform movements in a radial direction during the opening and closing of the mold.

[0028] The curing mold 10 is substantially rotationally symmetrical with a central axis X-X'. The central axis extends vertically. In the remainder of the description, "axial" or "axially" refers to a direction or displacement parallel to the central axis, and "radial" or "radially" refers to a direction or displacement perpendicular to the central axis X-X'. A circumferential direction is a direction tangent to the radial direction and corresponds to the circumferential direction of the tire.

[0029] The circumferential sectors of the crown 20 are arranged side by side in the circumferential direction and each sector of the crown is divided into two parts, upper and lower, preferably by a radial plane which is, in the example shown, a median plane M, that is to say a plane which passes at an equal distance from the beads of the tire, therefore from the molding rings 18a, 18b. More precisely, each sector comprises an upper sector part 20a and a lower sector part 20b, the upper 20a and lower 20b parts being located on either side of the plane M so as to come into contact when the mold is closed and to move away from each other when the mold is opened, such which will be explained later. Each sector portion comprises a lining for molding the tread patterns of the tire held by a sector support. Thus, the upper sector portion 20a comprises a lining 19a which extends from the interface with the lower portion 20b to the interface with the upper shell 16a. Similarly, the lower sector portion 20b comprises a lining 19b which extends from the interface with the upper portion 20a to the interface with the lower shell 16b. As seen in Figure 1, the linings 19a, 19b extend beyond the tread and are intended to mold a tire whose tread patterns extend onto the sidewalls.

[0030] The radially external surfaces 21a and 21b of the supports of the linings of the upper 20a and lower 20b parts of the sector are conical, they have the same inclination extending downwards and radially outwards.

[0031] The press further comprises a conical crown 14 whose radially inner surface 14a is inclined radially downwards and has the same inclination as the radially outer surfaces 21a and 21b. The conical crown is connected to an actuator of the baking press, for example a hydraulic cylinder, which allows it to perform an axial movement upwards and downwards. When the mold is closed, the conical crown 14 descends, it is positioned on the ring of sectors 20, it brings the sectors radially inside the mold and applies a force to the sectors to keep the assembly closed during baking when the temperature inside the molding cavity increases. The conical crown 14 comprises a plurality of slides 12 each rigidly fixed on the conical crown, each slide being intended to slide in a rail of a corresponding sector of the crown 20.Stops located between one end of the slide 12 and a notch in the external surface 21a of each sector make it possible to limit the radial recoil travel of the sectors when the conical crown is moved upwards to open the mold. In this exemplary embodiment, the conical crown 14, the slides 12 and their connecting elements to the mold sectors and to the upper plate of the press are of the type described in document WO 2014 / 044713.

[0032] The upper platen 2 of the press is connected to another actuator, such as a hydraulic cylinder, which allows it to perform an axial movement up and down during the operations of closing and opening the mold, as will be explained later.

[0033] In the open position of the mold, the conical crown 14 as well as the upper molding parts: the upper parts 20a of the sectors, the upper shell 16a, the upper molding ring 18a integral with the upper plate 2 of the press are moved axially upwards so as to clear the molding cavity in order to be able to extract the baked tire and to introduce a new tire blank. When closing the mold, the upper plate descends and, the upper parts 20a of the sectors being moved back radially outwards, the conical crown 14 descends to close the baking cavity and therefore the mold for baking. The heat transfer fluid arrives inside the molding cavity from a device 25 located in the central part of the baking cavity, comprising for example a baking membrane which presses the tire blank against the internal parts of the mold during baking.

[0034] According to the invention, each lower sector part 20b is provided with a device 100 for holding the lower sector part 20b in radial position between a mold closing position and a mold opening position.

[0035] In the first embodiment better visible in Figures 1, 2a and 2b, the elements of the holding device 100 belong to the lower part 20b of the sector and to the lower shell 16b. More precisely, the holding device 100 comprises a slide 101 capable of moving in a cavity 102, of elongated shape extending in the radial direction, made at the base of the lower part 20b of the sector which cooperates with a pusher 108 arranged in a sole 110 of the lower shell 16b. The slide 101 is rigid, it has the shape of an elongated beam extending between the lower shell 16b and the lower part of the sector 20b, and has for example a dovetail section.In another example (not shown) the section of the slide has a T shape or it has any suitable shape allowing it both radial translational guidance of the lower sector part, while preventing axial movement of the latter when it is subjected to a force having an axial component. The sole 110 is rigidly fixed on the lower shell 16b for example using fixing screws. More precisely, the sole 110 comprises an orifice 107 in which the pusher 108 and a return spring 109 are arranged which pushes the pusher axially outwards, the axially lower end 108' of substantially rounded shape of the pusher 108 being protruding relative to that of the sole 110. The axially lower surface 110' of the sole 110 is provided with two. cavities 112 and 114 located on either side of the pusher 108. The slide 101 comprises a roller 105 mounted free to rotate about its central axis, the roller being located at the axially outer end of the slide and comes to cooperate with the notches 112 and 114, during the radial displacement of the lower part 20b of the sector. The sole 110 further comprises a stop 115 which allows the roller to take place in a stable manner in the notch 114. The slide 101 is integral with the lower part 20b of the sector by being fixed thereto by means of a pin 116 inserted in an orifice 117, with an axis transverse to the longitudinal direction of the slide 101, of the lower part 20b of the sector and to a fixing screw transverse to the axis of the orifice 117 (not illustrated).

[0036] In operation, the roller 105 of the slide 101 is placed in the notch 112 when the mold is in the closed position. When the mold is opened, the lower part 20b of the sector moves radially outward and the roller 105 of the slide 110 follows the movement of the sector and actuates the pusher 108 against the return spring 109. At the end of the radial recoil movement of the lower part 20b of the sector, the roller 105 arrives in the second notch 114 in which it is held on the one hand by the protruding part 108' of the pusher 108 which returns to its place under the effect of the spring 109 and on the other hand by the stop 115.

[0037] The slide 110 takes two stable positions during its movement: a first corresponding to the closed position of the mold, when the roller 105 takes place in the notch 112, and the second corresponding to the open position of the latter, the roller 105 coming to be housed in the notch 114 of the sole 110 under the ratchet effect of the pusher 108. This allows the lower part 20b of the sector to be maintained in axial and radial position and to prevent any movement of the latter in the open position of the mold.

[0038] The operation of the mold according to the first embodiment of the invention will now be explained with reference to Figures 3a to 3i. Figure 3a illustrates the curing mold 10 in the closed or curing position to obtain a tire P, the roller 105 being located in the notch 112 of the sole 110. Figure 3b illustrates the step of starting to open the mold when a force is exerted in an axial direction on the conical crown 14, which causes the upper and lower parts of the sectors to recoil radially simultaneously. A device, for example of the protruding finger type at the upper part 20a of the sector which cooperates with an orifice in the lower part 20b of sector at the interface of these parts, allows synchronization between the upper 20a and lower 20b parts of each sector (not shown). The roller 105 has left the notch 112. Once the radial retraction of the sectors has been carried out, the upper parts of sector 20a separate from the lower parts of sector 20b at the level of the radial plane M.

[0039] Figure 3c illustrates the fully open position of the mold, a position in which the upper molding part is axially spaced apart in order to be able to extract the baked tire. The roller 105 cooperates in this position with the notch 114 of the sole 110 and holds the lower sector part 20b in position.

[0040] Figures 3d and 3e illustrate vacuum mold closing steps. The mold is closed by axially lowering the upper plate 2 and the conical crown 14.

[0041] Figure 3f illustrates a step of opening the mold, but only axially (or vertically), without radial recoil of the sectors, in particular the upper 20a and lower 20b parts of the sectors. The lower sector parts 20b are held against the lower shell 16b thanks to the force of the spring 109 of the pusher 108 which applies a force to the roller 105 of the slide 101. The actuator in movement of the upper parts 20a of the sectors holds them against the upper shell 16a. A new tire blank E can be introduced into the molding cavity, as visible in Figure 3g. The mold is then closed axially only (or vertically), as illustrated in Figure 3h and curing can take place when the mold is completely closed, as illustrated in Figure 3i.

[0042] This additional step of vacuum closing the mold before opening it only axially (or vertically) makes it possible to bring the upper parts of the sectors and the lower parts of the sectors back into radial position before introducing a new tire blank and thus to avoid pinching of the rubber at the interfaces between the radially external end of each upper part 20a, respectively lower part 20b and the upper shell 16a respectively lower 16b. The appearance of the cured tire is thus improved.

[0043] In a second embodiment better visible in figures 4, 5a, 5b and 6, all the elements of the holding device 100 also belong to the lower part of sector 20b and to the lower shell 16b. More precisely, the holding device 100 comprises a slide 121 comprising two notches 124 and 126 which cooperate with a pusher 103 belonging to the lower part of sector 20b. The slide 121 is rigidly fixed by its radially outer end 121' to the lower shell 16b, by any suitable means, for example by a screw fixing (not shown), the other end of the slide being free. The slide 121 is rigid, it has the shape of an elongated beam extending between the lower shell 16b and the lower part of sector 20b, and has a section for example in the shape of a dovetail.The lower sector part 20b comprises at its base an elongated orifice 122 having a shape complementary to that of the slide 121, more precisely, it has a cross-section of the same shape as the slide, in the form of a dovetail for the example illustrated in the figures, but of larger dimensions than this in order to allow the radial sliding of the lower sector part 20b relative to the slide 121. The lower sector part 20b comprises a pusher 103 of the type comprising a ball 118 pushed downwards by a return spring 119.

[0044] In operation, the ball 118 of the pusher 103 is placed in the notch 124 when the mold is in the closed position. When the mold is opened, the lower part 20b of the sector moves radially outward and the ball 118 of the pusher 103 follows the movement of the sector by rolling on the slide 121, compressing the return spring 119. At the end of the radial recoil movement of the lower part 20b of the sector, the ball 118 of the pusher 103 arrives in the second notch 126 in which it is held under the effect of the return spring 119 which relaxes. A stop 128 prevents any radial movement of the lower part of the sector 20b beyond this position.

[0045] The lower sector part 20b takes two stable positions during its movement: a first corresponding to the closed position of the mold, when the pusher 103 takes place in the notch 124, and the second corresponding to the open position of the latter, the pusher 103 being housed in the notch 126 of the slide 121 by a ratchet effect. This allows the lower sector part 20b to be held in axial and radial position and to prevent any movement of the latter in the open position of the mold.

[0046] The operation of the mold according to the second embodiment of the invention will now be explained with reference to Figures 7a to 7i. Figure 7a illustrates the mold of cooking 10 in closed position or cooking to obtain a tire P, the ball 118 of the pusher 103 being located in the notch 124 of the slide 121. Figure 7b illustrates the step of starting to open the mold when a force is exerted in an axial direction on the conical crown 14, which causes the radial retraction of the upper and lower parts of the sectors simultaneously. A device, for example of the protruding finger type at the level of the upper part 20a of the sector which comes to cooperate with an orifice of the lower part 20b of the sector at the interface of these parts, allows the synchronization between the upper 20a and lower 20b parts of each sector (not shown). The ball 118 of the pusher 103 has left the notch 124. Once the radial retraction of the sectors has taken place, the upper parts of the sector 20a separate from the lower parts of the sector 20b at the level of the radial plane M.

[0047] Figure 7c illustrates the fully open position of the mold, a position in which the upper molding part is axially spaced apart in order to be able to extract the cured tire. The ball 118 of the pusher 103 cooperates in this position with the notch 126 of the slide 121 and holds the lower sector part 20b in position.

[0048] Figures 7d and 7e illustrate steps for vacuum closing the mold. The mold is closed by axially lowering the upper plate 2 and the conical crown 14.

[0049] Figure 7f illustrates a step of opening the mold, but only axially (or vertically), without radial recoil of the sectors, in particular the upper 20a and lower 20b parts of the sectors. The lower sector parts 20b are held against the lower shell 16b thanks to the force of the spring 119 of the pusher 103 which presses the ball into the notch of the slide 121. The actuator in movement of the upper parts 20a of the sectors holds them against the upper shell 16a. A new tire blank E can be introduced into the molding cavity, as visible in Figure 7g. The mold is then closed axially only (or vertically), as illustrated in Figure 7h and curing can take place when the mold is completely closed, as illustrated in Figure 7i.

[0050] As explained previously, this additional step of vacuum closing the mold before opening it only axially (or vertically) allows the upper parts of the sectors and the lower parts of the sectors to be brought back into radial position. before the introduction of a new tire blank and thus avoid pinching of the rubber at the interfaces between the radially external end of each upper part 20a, respectively lower part 20b and the upper shell 16a respectively lower shell 16b. This makes it possible to avoid the appearance of burrs on the cured tire.

[0051] Other variations and embodiments of the invention may be contemplated within the scope of the invention as claimed. Thus, the upper sector portion and the lower sector portion may be axially separated along a radial plane which is other than the median plane or along a plane which is not radial.

Claims

Claims 1. Baking mold (10) for tire comprising: - an upper shell (16a) for molding a tire sidewall, - a lower shell (16b) for molding a tire sidewall, - a ring of circumferential sectors (20) for molding a tire tread, each sector comprising an upper sector part (20a) capable of being axially separated from a lower sector part (20b), the curing mold being capable of cooperating with - means for actuating in a radial movement of all the sector parts simultaneously and in an axial movement of the upper part (20a) of each sector relative to the lower part (20b) of the same sector during the operations of opening and closing the mold, characterized in that each lower part (20b) of the sector comprises a device (100) for holding in the radial position of the lower part of the sector (20b) between a closed position of the mold and an open position thereof, the elements of the holding device (100) belonging to the lower part of the sector and to the lower shell (16b).

2. Mold according to claim 1, characterized in that said device is made in such a way as to allow the lower sector part (20b) to be held in axial position.

3. Mold according to one of the preceding claims, characterized in that said holding device (100) comprises a slide (101, 121) extending in a radial direction which cooperates with a pusher (103, 108) made so as to exert an axial force thereon during the radial movement of the lower part (20b) of the sector.

4. Mold according to claim 3, characterized in that the slide (101) is movable with the lower sector part (20b) and that said pusher (108) is fixed on the lower shell (16b) by means of a sole (110).

5. Mold according to the preceding claim, characterized in that the slide (101) comprises a roller (107) which cooperates with two notches (112, 114) arranged on either side and other of the pusher (108) in the sole (110) during the radial movement of the lower part (20b) of the sector. Mold according to claim 3, characterized in that the slide (121) is fixed on the lower shell (16b) and the pusher (103) is movable with the lower part of the sector (20b). Mold according to the preceding claim, characterized in that the slide (121) comprises two notches (124, 126) which cooperate with a ball (118) of the pusher (103) during the radial movement of the lower part of the sector (20b). Mold according to one of claims 3 to 7, characterized in that said pusher (103, 108) comprises a return spring (109, 119).Mold according to the preceding claim, characterized in that said return spring (109, 119) is calibrated so as to be able to maintain the lower part (20b) of the sector in a predefined position when the force exerted on the pusher (103, 108) is less than the force it undergoes when closing the mold. Mold according to one of claims 3 to 9, characterized in that the slide (101, 121) has a dovetail-shaped section. Method for molding a tire blank using a curing mold comprising. - an upper shell (18a) for molding a tire sidewall, - a lower shell (18b) for molding a tire sidewall, - a crown of circumferential sectors (20) for molding a tire tread, each sector comprising an upper sector part (20a) capable of being separated axially from a lower sector part (20b), the baking mold being capable of cooperating with - means for actuating in a radial movement of all the parts of sectors simultaneously and in an axial movement of the upper part (20a) of each sector relative to the lower part (20b) of the same sector during the operations of opening and closing the mold, the method including a step of extracting the tire at the end of cooking when all the sectors are moved radially outwards simultaneously and when the upper part (20a) of each sector is moved axially upwards, the lower part (20b) of the sector being caused to move from a first position of holding in position radially on the inside to a second position of holding radially on the outside.

12. Molding method according to the preceding claim, characterized in that it comprises a step of vacuum closing the mold followed by a step of opening the mold without radial retraction of the sectors to introduce a tire blank inside the mold.

13. Molding method according to the preceding claim, characterized in that the mold is closed axially only on the tire blank introduced inside the mold.

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