Tire manufacturing method and apparatus

Abstract

A tyre manufacturing method and apparatus (1) wherein: a bare carcass (5) without any tread is provided; a winding system (7) winding a raw rubber liner (8) and a pre-cured tread strip (9) around the surface of the carcass (5); and a curing system (10) curing the raw rubber liner (8) inserted in the tire (2) between the carcass (5) and the tread strip (9). In the curing system, the tyre (2) is inserted into a sealed curing chamber (11) which is pressurized beyond ambient pressure and inflated. The curing chamber is delimited by two opposing base walls (12) having a circular shape and a side wall (13) having a cylindrical shape and connecting the two base walls (12) to each other. The side wall (13) is moved axially towards and from the two base walls, respectively, by means of a displacement device (15) in order to close and open the curing chamber.

Description

[0001] manual Technical Field

[0002] The present invention relates to a tire manufacturing method and apparatus.

[0003] The present invention finds advantageous application in the field of "truck" tyre retreading, to which the ensuing discussion will make explicit reference without loss of generality. Prior art

[0004] Traditionally, after the first use, "truck" tires are retreaded, that is, they are provided with a new tread to replace the old worn tread previously removed. The retreading of "truck" tires provides for mechanically removing the old worn tread from the used tire to expose the carcass, and subsequently applying the new tread to the carcass. Applying the new tread to the carcass provides for winding a tread strip around the carcass; the carcass is then subjected to a curing process to determine the best adhesion of the tread to the carcass. In the hot retreading process, the tread strip is raw and without a pattern, the pattern being achieved during the curing step in a curing press provided with a mold having the desired pattern. During the thermal retreading process, curing is carried out at high temperature (about 150°C to 160°C) and high pressure (approximately about 1.4MPa-1.6MPa, i.e. 14 bar-16 bar), which is required to make the rubber sufficiently fluid to flow into the mold so as to form a pattern during curing; however, the thermal and mechanical stresses to which the carcass is subjected due to such high temperature and high pressure may cause damage to the carcass.

[0005] During the cold retreading process, the tread strip (called "PCT - pre-cured tread-strip") is pre-cured and already provided with a pattern, and an intermediate strip or liner with bonding function is inserted between the carcass and the pre-cured tread strip. During the cold retreading process, curing only means curing the liner in order to determine the best adhesion of the tread strip to the carcass by means of the bonding action of the liner (i.e. the pattern is not printed during curing); therefore, during the cold retreading process, curing is carried out at a lower temperature (approximately 100°C-125°C) and a lower pressure (approximately 0.4MPa-0.6MPa, i.e. 4 bar-6 bar), so that the carcass is subjected to lower thermal and mechanical stresses.

[0006] Generally speaking, the hot retreading process provides an average cure period of about 1 hour per "truck" tire, while the cold retreading process provides an average cure period of about 4 hours per "truck" tire.

[0007] During the cold retreading process and in order to ensure adequate adhesion of the tread strip to the carcass (by inserting a liner consisting of a strip of raw rubber), a radial thrust pressing the tread strip against the carcass must be applied during curing. In known manufacturing plants, this radial thrust is obtained by inserting the tire into an autoclave in which an overpressure relative to atmospheric pressure is achieved (approximately 0.6 MPa, or 6 bar); and by inserting the tire into a flexible envelope in which a vacuum is initially created and which is subsequently inflated with air to a pressure of about 0.45 MPa, or 4.5 bar; the difference in pressure maintained during the curing cycle results in the generation of a pneumatic thrust pressing the tread strip against the carcass.

[0008] The use of an autoclave and of an envelope makes it possible to apply a uniform thrust to the entire tread strip, both at the peaks and at the valleys of the pattern, and therefore makes it possible to ensure optimal tread adhesion to the carcass.

[0009] Patent applications WO2020188502A1 and WO2020188503A1 disclose a method for cold retreading of tires, wherein the liner is made of a composite comprising a conductive material, and the curing process comprises: connecting the liner to a heat source or a power source; in this way, during the curing process, only the liner (instead of the entire tire) is heated to the curing temperature, and therefore energy can be saved and thermal stress on the entire tire can be reduced.

[0010] Patent application WO2013029974A1 discloses a method and apparatus for retreading vehicle pneumatic tires, wherein a vulcanized tread is bonded to a prepared tire carcass by a vulcanized bonding rubber layer; a conductive layer made of a rubber composition is located between the tread and the tire carcass and contains at least one conductive filler for heating by means of an electric current.

[0011] Patent US4123306A discloses a method and system for retreading tires, wherein an uncured gel layer disposed between a vehicle tire carcass and a pre-cured tire tread is vulcanized by radio frequency energy.

[0012] Patent application EP1435287A2 discloses a method and apparatus for partial deep curing of a tire inner liner; the apparatus comprises: a drum; a heat exchange chamber located on the inner surface of the drum; a shell surrounding the drum; a space between the outer surface of the drum and the shell; an inflatable seal located within the shell at each end of the shell, so that by inflating the seal, the seal expands and encloses the space between the drum and the shell; a gas inlet for supplying gas to the space and pressurizing the space; a heat source connected to the heat exchange chamber for heating the drum; and a coolant source connected to the heat exchange chamber for cooling the drum.

[0013] Patent application WO2013002823A1 discloses a method and a device for mounting a tread ring onto a tire carcass. DETAILED DESCRIPTION

[0014] The object of the present invention is to provide a tire manufacturing method and a tire manufacturing plant having an easy and economical implementation and at the same time allowing a very uniform heating of the applied pad and a very uniform thrust to the entire tread strip.

[0015] According to the present invention, there is provided a tyre manufacturing method and a tyre manufacturing apparatus as described in the accompanying claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will now be described with reference to the accompanying drawings, which show non-limiting exemplary embodiments, in which:

[0017] · Figure 1 is a schematic diagram of a tire cold manufacturing apparatus according to the present invention and provided with a curing system;

[0018] · Figure 2 It is a perspective view of the curing system;

[0019] · Figure 3 is a perspective view with portions of the curing system removed for clarity;

[0020] · Figure 4 is a schematic diagram of a curing chamber of a curing system;

[0021] · Figure 5 and Figure 6 is a perspective view with portions of components of a curing chamber removed for clarity;

[0022] · Figure 7 , Figure 8 and Fig. 9 Removed for clarity. Figure 5 and Figure 6 Different exploded views of parts of components;

[0023] · Fig.10 yes Fig. 9 an enlarged view of a detail; and

[0024] · Fig.11 and Fig.12 is a perspective view and schematic diagram of the electrical contacts of the curing system.

[0025] Preferred embodiments of the present invention

[0026] exist Figure 1In the figure, a manufacturing device for producing tires 2 is indicated by numeral 1; in particular, the manufacturing device is configured to retread used tires 2 (but may also be configured to produce new tires).

[0027] Manufacturing plant 1 comprises a removal system 3, wherein old worn tread (not shown) is mechanically removed from tire 2, thereby exposing equatorial surface 4 of carcass 5 of tire 2. In other words, removal system 3 produces a bare carcass 5 presenting equatorial surface 4 without any tread.

[0028] Furthermore, the manufacturing device 1 comprises a scraping system 6 in which the equatorial surface 4 of the carcass 5 is scraped to remove any local damage; the scraping operation causes the formation of pits of random and variable size and position on the equatorial surface 4 of the carcass 5, which are subsequently filled with raw rubber.

[0029] The manufacturing plant 1 comprises a winding system 7 to which the carcass 5 is conveyed at the end of filling; inside the winding system 7, an intermediate strip or liner 8 of green rubber and a precured tread strip (PCT) 9 are wound (one after the other) around the carcass 5. It is important to observe that the precured tread strip 9 has been cured in a special mould before being wound around the carcass 5 and that it is provided with a tread pattern.

[0030] The manufacturing plant 1 comprises a curing system 10 in which the retreaded tyre 2 (i.e. provided with a pre-cured tread strip 9) is subjected to a curing process for curing the liner 8 interposed between the carcass 5 and the pre-cured tread strip 9, thus resulting in optimal adhesion of the pre-cured tread strip 9 to the carcass 5 by means of the bonding action of the liner 8. It is important to note that during the curing process, only the curing of the tread strip 8 is performed, without printing any kind of pattern on the pre-cured tread strip 9 already provided with a tread pattern.

[0031] The liner 8 is at least partially electrically conductive and during the curing process in the curing system 10 the liner 8 is heated by an electric current passing through the liner 8 .

[0032] According to one possible embodiment, the liner 8 is manufactured as disclosed in patent application WO2020188503A1 and thus utilizes a material selected from graphite, graphene and having a thickness greater than or equal to 300 m 2 The invention is prepared by combining a composite of 1 to 30 phr of at least one conductive material with carbon black having a surface area of ​​1 to 50 g / gr.

[0033] like Figure 4As shown, the curing system 10 includes a sealed curing chamber 11, into which the tire 2 is inserted during the curing process, and which is pressurized above the ambient pressure (the overpressure is approximately 0.6 MPa, i.e. 6 bar), thereby exerting a thrust on the precured rubber strip 9 in a known manner, which thrust (through the inserted liner 8) pushes the precured rubber strip 9 against the carcass 5; specifically, as is known, when the tire 2 is in the curing chamber 11, the tire 2 is also inflated at an overpressure equal to that of the curing chamber 11.

[0034] The curing chamber 11 is defined by two opposite base walls 12 having a circular shape and a side wall 13 having a cylindrical shape and connecting the two base walls 12 to each other. Figure 2 and Figure 3 The displacement device 15 shown in FIG. 1 is axially (ie, along the direction of the displacement device 15) to and from the two base walls 12, respectively. Figure 2 The central symmetry axis 14 shown in FIG. 1 is moved to close (as shown in FIG. Figure 4 as shown) and open (as shown Figure 2 and Figure 3 In other words, the displacement device 15 causes the side wall 13 to be ( Figure 2 and Figure 3 ) open position and ( Figure 4 1 and 12. The curing chamber 11 is axially movable between a closed position (shown in FIG. 1 ), in which the sidewall 13 is away from the base wall 12 and thus the curing chamber 11 is radially opened to unload the cured tire 2 and load a new tire 2 to be cured, and in the closed position, the sidewall 13 is connected to the base wall 12 to close (seal) the curing chamber 11 to implement the curing process.

[0035] According to a preferred embodiment, only the side wall 13 is axially movable to open and close the curing chamber 11 , while the two base walls 12 are not axially movable to open and close the curing chamber 11 .

[0036] According to a preferred embodiment shown in the drawings, when the curing chamber 11 is closed (eg Figure 4 ), the two base walls 12 are completely arranged in the side wall 13. In other words, the outer diameter of the two base walls 12 is substantially equal to (in fact, it is slightly smaller than) the inner diameter of the side wall 13.

[0037] Each base wall 12 comprises an annular sealing gasket 16 arranged on the edge of the base wall 12 so that when the curing chamber 11 is closed (eg Figure 4 The annular sealing gasket 16 is inserted between the base wall 12 and the side wall 13 when the curing chamber 11 is pressurized to ensure the sealing of the curing chamber 11. According to a preferred embodiment shown in the drawings, each base wall 12 includes an annular groove arranged on the edge of the base wall 12 and accommodating the annular sealing gasket 16.

[0038] According to a preferred embodiment, each annular sealing gasket 16 is inflatable, that is, it can be increased in size by being inflated and can be reduced in size by being deflated. Figure 4 The pneumatic device 17 (schematically shown in the figure) is configured to inflate the annular sealing gasket 16 after the curing chamber 11 has been closed (to increase the pneumatic seal before pressurizing the curing chamber 11) and to deflate the annular sealing gasket 16 before the curing chamber 11 is opened (to reduce the friction against the side wall 13 and thereby allow displacement of the side wall 13).

[0039] like Figure 3 As better shown, the displacement device 15 comprises: two parallel rails 18 arranged axially (i.e. parallel to the central axis of symmetry 14) above the side wall 13; and four slides 19, each of which slides along a corresponding rail 18. In addition, the displacement device 15 comprises two rods 20, each of which has a U-shape, which are connected to the side wall 13 and to two corresponding slides 19 in two different points; in other words, in each rod, the two vertical "legs" of the U-shape end at the side wall 13, while the horizontal central part of the U-shape is connected to the two slides at two opposite ends. According to different embodiments, not shown, the number and configuration of rails 18, slides 19 and rods 20 may be different.

[0040] According to a preferred embodiment, the tire 2 is formed by two clamps 21 (one of which is Figure 6 In one preferred embodiment, the two clamps 21 are supported in the curing chamber 11, the two clamps being arranged in the curing chamber 11 and being movable relative to each other to move towards and away from each other to clamp and release the tire 2, respectively. Specifically, the clamps 21 push against the annular bead area of ​​the tire 2. According to a preferred embodiment, the clamps 21 are fixed on the inner side of the base wall 12 (i.e. each clamp is supported by the corresponding base wall 12); in this embodiment, one base wall 12 (i.e. one clamp 21) is directly fixed to the frame of the curing chamber 11 and never performs any axial movement relative to the frame, while the other base wall 12 (i.e. the other clamp 21) is able to move axially to move the corresponding clamp 21 towards and away from the other clamp 21. The clamps 21 together with the base wall 12 or only the clamps 21 may have a rotational movement to correctly position the tire 2 on the bead; in other words, the clamps 21 may have a rotational movement to correctly position the tire 2 by allowing the rotation of the tire 2 (in this way, the tire 2 can find the correct angular position).

[0041] It is important to point out that one base wall 12 can be axially moved (eg using a pneumatic or hydraulic cylinder) not in order to open and close the curing chamber 11 , but only in order to move the corresponding clamp 21 towards and away from the other clamp 21 .

[0042] like Figure 7 , Figure 8 and Fig. 9 As shown, the curing system 10 includes two power sources 22 and 23, which are arranged on two sides of the tire 2 in the curing chamber 11; in other words, each power source 22 or 23 is arranged in the curing chamber 11 and arranged on the side of the corresponding base wall 12. Before the curing process, the power source 22 is placed on the first side of the liner 8, and the power source 23 is placed on the second side of the liner 8 opposite to the first side. The curing system 10 includes ( Figure 4 2 and 3) is an electrical device 24 which is configured to apply a potential difference between the two power bodies 22 and 23 during the curing process to cause current to circulate through the pad 8 (which is inserted between the two power bodies 22 and 23 and thus constitutes a "conductive bridge" between the two power bodies 22 and 23). As described above, the pad 8 is at least partially conductive and thus allows current to circulate through itself (thereby generating heat according to the Joule effect) when subjected to the potential difference applied by the two power bodies 22 and 23.

[0043] According to a preferred embodiment, the power supply bodies 22 and 23 are also interchangeable for tires 2 of different sizes; that is, the power supply bodies 22 and 23 can be disassembled for replacement when the size of the tire 2 changes.

[0044] Specifically, the two power bodies 22 and 23 are pushed toward each other with a predetermined thrust to clamp the liner 8 between the two power bodies 22 and 23, thereby mainly forming a seal with the pressurized area (between the sidewall of the carcass 5 and the pre-cured tread strip 9), and also reducing the electrical contact resistance between the power bodies 22 and 23 and the liner 8. In other words, the pressurized area must be kept separate from the pre-cured tread strip 9, and for this purpose, the power bodies 22 and 23 are pushed toward each other with a predetermined thrust to form a seal isolating the pressurized area. In addition, in order to reduce the electrical contact resistance between the power bodies 22 and 23 and the liner 8, the two power bodies 22 and 23 must be well adhered to the liner 8, and therefore the two power bodies must be pushed toward each other, thereby clamping the liner 8 between the two power bodies.

[0045] According to a preferred embodiment, each power source body 22 or 23 has an annular rubber layer (referred to as a "flexible side wall substrate"), which has the function of an electrical insulator and also has the function of a gasket to ensure the necessary pneumatic sealing (like a sleeve). In other words, the annular rubber layer of each power source body 22 or 23 is designed as a gasket to ensure the necessary pneumatic sealing, and also provides good electrical insulation (as if made of rubber).

[0046] According to a preferred embodiment shown in the drawings, the first power source body 22 has a flat annular surface 25, which is made of a conductive material everywhere and is in contact with the first side of the pad 8 (i.e., configured to contact the pad 8). In other words, the entire flat annular surface 25 has the same potential everywhere and constitutes a single "large" electrode. Preferably, the power source body 22 is connected to the negative pole of the electrical device 24 that applies the potential difference, i.e., the ground pole (e.g., Figure 4 shown).

[0047] according to Figure 8 and Fig. 9 In a preferred embodiment shown in FIG. 1 , the power body 23 includes a plurality of pin-shaped contacts 26, each of which protrudes axially (vertically) from the power body 23 and makes contact with the second side of the pad 8 (i.e., the pin-shaped contact 26 is configured to contact the pad 8). According to a preferred embodiment, the pin-shaped contacts 26 are evenly arranged along the circumference. Preferably, each pin-shaped contact 26 is connected to the positive pole of the electrical device 24 that applies the potential difference.

[0048] like Fig. 9 and Fig.10 As shown, each pin-shaped contact 26 is connected to the electrical device 24 by means of a dedicated wire 27 (i.e., each wire 27 is connected to one and only one pin-shaped contact 26, and vice versa). Preferably, the wire 27 is plugged into a connector 28 that can be connected to the electrical device 24. In this way, the electrical device 24 can apply to each pin-shaped contact 26 a potential that is different from the potential of all other pin-shaped contacts 26 (i.e., each pin-shaped contact 26 can be individually controlled by the electrical device 24). It is important to point out that for the sake of clarity, in Fig. 9 and Fig.10 Only a very limited number of electrical wires 27 are shown in FIG. 1 , but, in practice, the curing system 10 comprises a dedicated electrical wire 27 for each pin-shaped contact 26 .

[0049] like Fig.11 and Fig.12As shown, each pin-shaped contact 26 comprises a (more or less sharp) tip 29 which comes into contact with the second side of the pad 8 and is spring-loaded. In other words, in each pin-shaped contact 26, the tip 29 is mounted so as to be able to slide axially inside the housing 30 and is pushed towards the outside of the housing by the spring 31. In this way, the thrust force exerted by each pin-shaped contact 26 against the pad 8 is substantially constant (it depends only on the elastic force generated by the spring 31, which is constant in a first approximation) and is therefore always the same for all pin-shaped contacts 26.

[0050] according to Fig. 9 and Fig.10 In a preferred embodiment shown in FIG. 2 , the pin-shaped contacts 26 are supported by a support ring 32 made of an electrically insulating material; in this way, each pin-shaped contact 26 is electrically insulated from the other pin-shaped contacts 26 .

[0051] According to a preferred embodiment, the electrical device 24 is configured to: control the intensity of the current flowing through each pin-shaped contact 26, the control being independent of the intensity of the current flowing through the other pin-shaped contacts 26; control the intensity of the current flowing through each pin-shaped contact 26 by controlling the voltage applied to each pin-shaped contact 26, and therefore also control the voltage applied to each pin-shaped contact 26, the control being independent of the voltage applied to the other pin-shaped contacts 26. Preferably, the electrical device 24 is configured to calculate (determine) the resistance experienced by each pin-shaped contact 26 (i.e. the resistance existing between the pin-shaped contact 26 representing the positive electrode and the power source body 22 representing the negative electrode), and calculate (determine) the local temperature of the pad 8 corresponding to the pin-shaped contact 26 from the resistance experienced by each pin-shaped contact 26 (specifically, determine the resistivity from the resistance, and then determine the temperature from the resistivity, because the law relating resistivity and temperature is known). Furthermore, the electrical device 24 is configured to feedback-control the intensity of the current flowing through each pin-shaped contact 26 using the local temperature of the pad 8 corresponding to each pin-shaped contact 26 as a feedback variable.

[0052] According to a preferred embodiment, the electrical parameters, in particular the current and the voltage, of each pin-shaped contact 26 are monitored and recorded during the curing process. In this way, after the curing process, it can be verified that the curing process has been performed in a correct manner.

[0053] The above-mentioned tire manufacturing equipment 1 is configured to retread used tires, and therefore, the exposed carcass 5 is obtained by removing the old worn tread from the used tire; according to different embodiments, the tire manufacturing equipment 1 is configured to produce new tires, and therefore the exposed carcass 5 is made by winding a flat rubber strip.

[0054] The tire manufacturing plant 1 described above has many advantages.

[0055] Firstly, the tire manufacturing apparatus 1 described above allows applying a very uniform heating of the pad 8 ; in other words, the heat is generated directly inside the pad 8 by the Joule effect (ie due to the current circulating through the pad 8 acting as a resistor) and is equal along the entire pad 8 .

[0056] The above-described tire manufacturing plant 1 allows minimizing energy consumption due to the fact that heat is generated directly and only where it is needed, namely in the liner which is the only component that has to be cured and therefore has to be heated.

[0057] The above-mentioned tire manufacturing equipment 1 exhibits a high productivity (measured as the number of tires 2 retreaded per unit time) to the extent that the curing process is particularly short: about 25 minutes to 35 minutes are sufficient to completely cure the liner 8 (using a very small amount of energy in total); this result is obtained because the heat is generated directly in the liner 8, while in a conventional curing autoclave, the heat in the autoclave must first heat the pre-cured tread strip 9 (arranged further outwardly), and then the heat is transferred from the pre-cured tread strip 9 to the liner 8.

[0058] Furthermore, the tire manufacturing apparatus 1 described above allows a very uniform pushing force to the entire precured tread strip 9 by applying the pushing force using a pneumatic system.

[0059] The above tire manufacturing equipment 1 allows the curing chamber 11 to be opened and closed in a quick and simple manner, and when the curing chamber 11 is open, the unloading of the cured tire 2 and the loading of a new tire 2 to be cured are very easy because the access to the curing chamber 11 is wide by removing the side wall 13.

[0060] Finally, the tyre manufacturing apparatus 1 described above is compact and relatively cheap.

[0061] List of reference numbers

[0062] 1 Refurbished equipment

[0063] 2 Tires

[0064] 3 Remove the system

[0065] 4 Equatorial surface

[0066] 5 Carcass

[0067] 6 Scraping system

[0068] 7 Winding system

[0069] 8 Pads

[0070] 9 Pre-cured tread strip

[0071] 10 Curing system

[0072] 11 Curing room

[0073] 12 Base wall

[0074] 13 Sidewall

[0075] 14 Central axis

[0076] 15 Lifting equipment

[0077] 16 O-ring sealing gasket

[0078] 17 Pneumatic equipment

[0079] 18 Track

[0080] 19 Slide

[0081] 20 shots

[0082] 21. Fixture

[0083] 22 Power supply body

[0084] 23 Power supply body

[0085] 24 Electrical installations

[0086] 25 Surface

[0087] 26 Pin-shaped contact

[0088] 27 Wire

[0089] 28 Connectors

[0090] 29 Tip

[0091] 30 Shell

[0092] 31 Spring

[0093] 32 Support ring

Claims

1. A tire manufacturing method comprising the following steps: Providing a naked carcass (5) without any tread having a toroidal shape and presenting an equatorial surface (4); In a winding system (7), a raw rubber liner (8) and a pre-cured tread rubber strip (9) are wound around the equatorial surface (4) of the carcass (5) to assemble a tire (2) having a toroidal shape; as well as curing the raw rubber liner (8) inserted into the tire (2) between the carcass (5) and the tread rubber strip (9) in a curing system (10); wherein in the curing system (10), the tire (2) is inserted into a sealed curing chamber (11) which has a cylindrical shape for accommodating the tire (2) in annular shape, is pressurized above ambient pressure and is inflated; and wherein the curing chamber (11) is defined by two opposite base walls (12) having a disc shape and a side wall (13) having a cylindrical shape and connecting the two base walls (12) to each other; The manufacturing method is characterized in that the side wall (13) is axially moved toward and from the two base walls (12) respectively by means of a displacement device (15) to close and open the curing chamber (11).

2. The tire manufacturing method according to claim 1, wherein: When the curing chamber (11) is closed, the two base walls (12) are completely arranged inside the side walls (13).

3. A method for manufacturing a tire according to claim 1 or 2, wherein each base wall (12) includes an annular sealing gasket (16), which is arranged on the edge of the base wall (12) so that it is inserted between the base wall (12) and the side wall (13) when the curing chamber (11) is closed to ensure an enclosed pressurized curing chamber (11).

4. A tyre manufacturing method according to claim 3, wherein each base wall (12) comprises an annular groove arranged on the edge of the base wall (12) and accommodating the annular sealing gasket (16).

5. A tyre manufacturing method according to claim 3 or 4, wherein each annular sealing gasket (16) is inflatable.

6. A method for manufacturing a tyre according to claim 5, and comprising the further step of inflating the annular sealing gasket (16) after the curing chamber (11) has been closed and deflating the annular sealing gasket (16) before the curing chamber (11) is opened.

7. A tire manufacturing method according to one of claims 1 to 6, wherein the shifting device (15) comprises at least one track (18), which is arranged axially; and at least one sliding member (19), which slides along two tracks (18) and supports the side wall (13).

8. A tyre manufacturing method according to claim 7, and wherein the displacement device (15) comprises: two parallel tracks (18), the two parallel tracks being arranged axially; Four slides (19), each of the four slides sliding along a corresponding track (18); as well as Two rods (20), each of which has a U-shape, are connected to the side wall (13) in two different points and to two corresponding slides (19).

9. A tire manufacturing method according to one of claims 1 to 8, wherein only the side wall (13) is axially movable to open and close the curing chamber (11), while the two base walls (12) are not axially movable to open and close the curing chamber (11).

10. A tyre manufacturing method according to one of claims 1 to 9, wherein the curing system (10) comprises two clamps (21) which are arranged in the curing chamber (11) and can be moved axially relative to each other to move towards and away from each other to clamp the tyre (2) and release the tyre (2), respectively.

11. A tyre manufacturing method according to claim 10, wherein each clamp (21) is mounted on the inner side of a corresponding base wall (12) and is interchangeable.

12. A tyre manufacturing method according to claim 11, wherein one base wall (12) is fixed to the frame and the other base wall (12) is axially movable to move the corresponding clamp (21) towards and away from the other clamp (21).

13. A tyre manufacturing method according to one of claims 1 to 12, wherein the curing chamber (11) between the base walls (12) is completely empty, so that the tyre (2) can be inserted into / removed from the curing chamber (11) by radial movement parallel to the base walls (12).

14. A tire manufacturing apparatus (1), comprising: A working system configured to provide a naked carcass (5) without any tread having a toroidal shape and presenting an equatorial surface (4); a winding system (7) configured to wind a green rubber liner (8) and a precured tread strip (9) around the equatorial surface (4) of the carcass (5) to assemble a tire (2) having a toroidal shape; as well as a curing system (10) configured to cure the raw rubber liner (8) inserted into the tire (2) between the carcass (5) and the tread strip (9); and wherein the curing system (10) comprises a sealed curing chamber (11) which has a cylindrical shape for accommodating the tire (2) in annular shape, is configured to accommodate the tire (2) and is pressurized above the ambient pressure; wherein the curing chamber (11) is defined by two opposite base walls (12) having a disc shape and a side wall (13) having a cylindrical shape and connecting the two base walls (12) to each other; The manufacturing device (1) is characterized in that a displacement device (15) is provided, which is configured to move the side wall (13) axially toward and from the two base walls (12) respectively to close and open the curing chamber (11).

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