Tire manufacturing drum and associated process

Abstract

This tire manufacturing drum (2) comprises a barrel (4), a compressed air flow channel (50), and two gripping modules (5), each equipped with: - contact surfaces (16) and retaining grooves (18); - an expansion mechanism (22); and - an elastic membrane (20). The gripping modules (5) are axially movable between: - a folding position in which the contact surfaces (16) are able to come into radial contact with the tire blank (8) by being located axially between ridges (40) of the tire blank (8), and - a forming position in which the retaining grooves (18) are able to receive the ridges (40). Figure for the abbreviation: Fig 1

Description

Title of the invention: Tire manufacturing drum and associated process technical field

[0001] The invention relates to the manufacture of tires.

[0002] In particular, the invention relates to a tire manufacturing drum comprising axially movable gripping units between a folding position and a forming position, and a method for folding and forming a tire from a tire blank and such a manufacturing drum. Previous techniques

[0003] A tire is divided into three distinct zones comprising a crown which includes in particular a crown reinforcement and a tread intended to come into contact with the ground, beads intended to ensure the grip of the tire on the rim of a wheel, and sidewalls intended to connect the crown to the beads.

[0004] To manufacture a tire, elements in the form of strands, strips, or plies are successively and circumferentially arranged on a manufacturing drum to form a cylindrical tire blank. The element of a tire blank that forms the carcass reinforcement of the tire is called the carcass plies. The carcass plies are also folded around the strands on this manufacturing drum. This manufacturing drum is generally called a finishing drum. Such a finishing drum is described in document EP 0 953 434 Bl.

[0005] A step called bead folding is then carried out, which consists of folding or folding the tire's bead edges to ensure a good fit and seal when the tire is mounted on a rim. This step is performed on a bead folding drum. Such a bead folding drum is described in document EP 1 798 022 AL

[0006] Next, the generally cylindrical tire blank is transformed into a toroidal tire blank on another manufacturing drum during a step called shaping. During this transformation, the top of the blank is stretched to increase its diameter by pressurizing the volume enclosed by the blank and the drum with air, and the flanges of the blank are brought axially closer together. This other manufacturing drum is generally called the finishing drum. Such a finishing drum is described in document WO 2020 / 128320 AL

[0007] The invention aims to reduce the costs associated with the manufacture of a tire. Description of the invention

[0008] The invention relates to a drum for manufacturing a tire from a tire blank which is provided with two ribs, two sides and a top, the manufacturing drum comprising a barrel extending axially and two tire blank gripping modules which are each movable in axial translation along the barrel, each gripping module being provided:

[0009] - of a tire blank gripping unit comprising a plurality of retaining sectors which are arranged circumferentially with respect to each other and which are each provided with a contact surface and a retaining groove;

[0010] - of an expansion mechanism configured to move the gripping unit said gripping module between a position radially close to the barrel and at least one position radially far from the barrel; and

[0011] - of an elastic membrane disposed in the retaining grooves of the unit gripping of said gripping module.

[0012] The elastic membranes of the gripping modules are intended to form in part a sealed chamber by contact with the pneumatic blank.

[0013] The manufacturing drum further includes at least one compressed air circulation path between a compressed air source external to the manufacturing drum and the sealed chamber.

[0014] According to a general characteristic, the gripping modules are axially mobile at least between:

[0015] - an axially close position called "folding" in which the surfaces contact points of the gripping units in said position radially distant from the barrel are capable of coming into radial contact with one of the flanks and / or the top of the tire blank by being located axially between the ridges of the tire blank, and

[0016] - an axially distant position referred to as a "conforming" position in which the grooves the retaining grooves of the gripping units in said position radially away from the barrel are suitable to accommodate the ridges of the tire blank, the axial distance between the retaining grooves of the gripping units being equal to the axial distance between the ridges of the tire blank.

[0017] The gripping units in the radially close position of the barrel allow the pneumatic blank to be arranged around the gripping units.

[0018] The gripping units in said position radially distant from the barrel allow the pneumatic blank whose inner diameter is equal to the outer diameter of the gripping units in said position radially distant from the barrel to be held.

[0019] The gripping units, simultaneously in the axially close folding position and in the radially distant position, are capable of holding the tire blank such that the ridges of the tire blank protrude axially on either side of the gripping units. Thus, an external tool, dedicated to folding, can operate on the ridges to perform a folding step.

[0020] This folding step relates in particular to folding the carcass ply and a bead protector around the associated bead, that is to say, folding the element of the tire blank forming the tire carcass reinforcement and a layer of rubber or composite material around the associated bead to encase the associated bead. This step protects the associated bead and ensures better bonding between the different layers of the tire.

[0021] The gripping units, simultaneously in the axially distant shaping position and in said radially distant position, are also capable of holding the tire blank. The air circulation channel then allows the sealed chamber to be pressurized in order to perform a shaping step during which the gripping units move axially closer together to give a toroidal shape to the tire blank.

[0022] The axial stroke and axial dimensions of the gripping units therefore make it possible to hold the tire blank, on the one hand, to carry out a folding step and, on the other hand, to carry out a shaping step, thus making it possible to reduce the number of tools required for the manufacture of tires.

[0023] In other words, with a single manufacturing drum, it is possible to carry out different steps necessary for the production of the tire.

[0024] Advantageously, the axial movement of the gripping modules is symmetrical to each other.

[0025] Optionally, in the axially close folding position, the gripping units are axially in contact with each other.

[0026] Advantageously, the expansion mechanism of each gripping module is configured to move the gripping unit of said gripping module between the radially close position of the barrel and at least the first and second radially distant positions of the barrel, and configured to immobilize the gripping unit of said gripping module at each of the first and second radially distant positions of the barrel.

[0027] The diameter of the gripping unit of said gripping module in the second position radially distant from the barrel is greater than the diameter of the gripping unit of said gripping module in the first position radially distant from the barrel.

[0028] Thus, the manufacturing drum allows the folding and shaping steps to be carried out on tire blanks whose inner diameter is equal to the outer diameter of the gripping units in each of the first and second positions radially distant from the drum.

[0029] Advantageously, the expansion mechanism of each gripping module is configured to move the gripping unit of said gripping module between the position radially close to the barrel and a third position radially far from the barrel, and configured to immobilize the gripping unit of said gripping module in the third position radially far from the barrel, the diameter of the gripping unit of said gripping module in the third position radially far from the barrel being greater than the diameter of the gripping unit of said gripping module in the second position radially far from the barrel.

[0030] Thus, the manufacturing drum allows the folding and shaping steps to be carried out on tire blanks whose inner diameter is equal to the outer diameter of the gripping units in each of the first, second and third positions radially distant from the drum.

[0031] Optionally, the expansion mechanism of each gripping module includes a rotary selector equipped with rotating rings and stops, said rotating rings being able to be at least in a first immobilization position of the gripping unit of said gripping module in the first position radially away from the barrel and in a second immobilization position of the gripping unit of said gripping module in the second position radially away from the barrel.

[0032] Optionally, said rotating rings are able to be at least in a third immobilization position of the gripping unit of said gripping module in the third position radially away from the barrel.

[0033] Optionally, the elastic membrane of each gripping unit includes polyurethane.

[0034] Polyurethane is particularly extensible and makes it possible to ensure the sealing of the chamber when the gripping units are at least in the first and second positions radially away from the barrel, and in particular in the first, second and third positions radially away from the barrel.

[0035] Optionally, the expansion mechanism of each gripping module includes an annular cylinder that is movable in axial translation along the barrel and a plurality of connecting rods that convert the axial movement of the annular cylinder into a radial movement communicated to the holding sectors of the gripping unit of said gripping module.

[0036] Thus, the expansion mechanism of each gripping module is compact, thereby facilitating the arrangement of the pneumatic blank around the gripping units in the radially close position of the barrel.

[0037] Preferably, the radial movement of the holding sectors of the gripping unit of said gripping module is a purely radial movement.

[0038] Advantageously, the expansion mechanism of each gripping module comprises a plurality of pneumatic supply channels, each comprising a pneumatic supply hose extending axially in a spiral inside the barrel.

[0039] Thus, the pneumatic supply routes do not clutter the volume outside the manufacturing drum and can follow the movement of the gripping modules.

[0040] The invention also relates to a method for folding and shaping a tire from a tire blank and a manufacturing drum as described above, the method comprising:

[0041] - the positioning of each gripping unit in the axial position close folding and positioning of the tire blank around the drum so that the sides and / or top of the tire blank are opposite the contact surfaces of the gripping units and so that the contact surfaces of the gripping units are located axially between the ridges of the tire blank;

[0042] - the radial displacement of each gripping unit in said position away from the barrel so that the contact surfaces of the gripping units are in contact with the sides and / or the top of the tire blank by being located axially between the ridges of the tire blank;

[0043] - the folding of the pneumatic blank, in particular carried out with the external tool to the manufacturing drum which is dedicated to folding;

[0044] - the displacement of each gripping unit in the radial position closer to the barrel;

[0045] - the positioning of each gripping unit in the axial position distant conformation and positioning of the pneumatic blank so that the ridges of the pneumatic blank are opposite the retaining grooves of the gripping units;

[0046] - the radial displacement of each gripping unit in said position away from the barrel so that the ridges of the pneumatic blank are in the retaining grooves of the gripping units; and

[0047] - the conformation of the pneumatic blank.

[0048] Advantageously, the conformation of the pneumatic blank includes pressurizing the sealed chamber and axially bringing the gripping units together.

[0049] Optionally, a rotation of at least one of the ridges of the pneumatic blank is carried out during the axial approach of the gripping units by sliding the elastic membrane concerned relative to the holding sectors of the gripping unit concerned. Brief description of the drawings

[0050] The present invention will be better understood upon study of the detailed description of an embodiment, taken by way of non-limiting example and illustrated by the accompanying drawings in which:

[0051] [Fig-1] is a longitudinal cross-sectional view of a manufacturing drum during a folding step according to an example of an embodiment of the invention;

[0052] [Fig.2] is a side view of the manufacturing drum of [Fig.1] on which elastic membranes of the drum were not shown;

[0053] [Fig.3], [Fig.4] and [Fig.5] are cross-sectional views of a rotary selector of the manufacturing drum along the axis AA of [Fig.1] when the gripping units are respectively in a first, second and third position radially away from the drum;

[0054] [Fig.6] is a cross-sectional view of one of the gripping units of the manufacturing drum along the axis A-A' of [Fig.1] when this gripping unit is in the second position radially away from the drum;

[0055] [Fig.7] is a side view of a drum manufacturing gripping module the [Fig.l] during the folding stage;

[0056] [Fig.8] is a side view and partly longitudinal section of the manufacturing drum of [Fig.1] during a shaping step;

[0057] [Fig.9] schematically illustrates a folding and shaping process of a pneumatic according to an example of an embodiment of the invention. Detailed description

[0058] Fig. 1 represents a longitudinal section of a manufacturing drum 2 of a tire.

[0059] The manufacturing drum comprises a frame (not shown), a barrel 4 extending axially from the frame along a longitudinal axis X-X', and two gripping modules 5 which are each equipped with a gripping unit 6 of a pneumatic blank 8 and which are mobile in axial translation along the barrel 4.

[0060] The shaft 4 extends from the frame and is rotationally mobile about the X-X' axis relative to the frame. Each gripping module 5 is rotationally fixed relative to the shaft 4.

[0061] The manufacturing drum 2 also includes means for driving the gripping modules 5 in axial translation, for example a motor (not shown), a threaded rod 10 which is located in the barrel 4 and which is driven by the motor so as to be mobile in rotation relative to the frame, and nuts 12 which are provided with transmission fingers and which are capable of converting the rotational movement of the threaded rod 10 into a translational movement of the gripping modules 5.

[0062] Each gripping unit 6 is provided with a plurality of retaining sectors 14 which are arranged circumferentially with respect to each other and which are each provided with a contact surface 16 and a retaining groove 18 distinct from the contact surface 16. The retaining sectors 14 are arranged circumferentially so as to create a continuous ring of sectors in the circumferential direction.

[0063] The retaining grooves 18 of each gripping unit 6 are axially offset on the side of the other gripping unit relative to the contact surfaces 16 of said gripping unit. The retaining grooves 18 of each gripping unit 6 are radially offset inwards relative to the contact surfaces 16 of said gripping unit.

[0064] Each gripping module 5 is provided with an elastic membrane 20 disposed in the retaining grooves 18 of the gripping unit 6.

[0065] Each elastic membrane 20 is annular and conforms to the shape of the retaining grooves 18 of the associated gripping unit 6, in particular conforms to a bottom of the retaining grooves 18 of the associated gripping unit 6.

[0066] In the example shown, and with reference to [Fig.2] on which the elastic membrane 20 and the pneumatic blank 8 have not been shown for reasons of clarity, each retaining sector 14 comprises a first part 14a which is provided with the contact surface 16 and a second part 14b which is provided with the retaining groove 18.

[0067] The retaining sectors 14 are nested together in the circumferential direction. In particular, the first parts 14a are nested together in the circumferential direction and the second parts 14b are nested together in the circumferential direction.

[0068] Alternatively, each retaining sector 14 could comprise a single piece provided with the contact surface 16 and the retaining groove 18.

[0069] Each gripping module 5 is equipped with an expansion mechanism 22 capable of modifying the diameter of the gripping unit 6 of the associated gripping module 5. Each expansion mechanism 22 is capable of moving the associated gripping unit 6 between a position radially close to the barrel 4 and at least one first position radially far from the barrel 4, in particular between a position radially close to the barrel 4 and at least the first and second positions radially far from the barrel 4, and more precisely between a position radially close to the barrel 4 and the first, second and third positions radially far from the barrel 4.

[0070] The outer diameter of the gripping units 6 in the position radially close to the barrel 4 is strictly less than the outer diameter of the gripping units 6 in the first position radially far from the barrel 4, which is itself strictly less than the outer diameter of the gripping units 6 in the second position radially far from the barrel 4, which is itself strictly less than the outer diameter of the gripping units 6 in the third position radially far from the barrel 4.

[0071] Each expansion mechanism 22 is capable of radially immobilizing the associated gripping unit 6 in the radially close position of the barrel 4 and in the first radially distant position of the barrel 4, in particular in the radially close position of the barrel 4 and in the first and second radially distant positions of the barrel 4, and more precisely in the radially close position of the barrel 4 and in the first, second and third radially distant positions of the barrel 4.

[0072] Each expansion mechanism 22 includes an annular cylinder 24 which is arranged circumferentially around the barrel 4 and which is movable in axial translation along the barrel 4, and includes a plurality of connecting rods 26 each connected to the annular cylinder 24 of the associated expansion mechanism 22 and to one of the retaining sectors 14 of the associated gripping unit 6, the connecting rods 26 being able to convert the axial movement of the annular cylinder 24 of the associated expansion mechanism 22 into a purely radial movement communicated to the retaining sectors 14 of the associated gripping unit 6.

[0073] To obtain purely radial movement, each retaining sector 14 of the gripping unit 6 is connected to the annular cylinder 24 of the associated expansion mechanism 22 by a pair of connecting rods 26 of the same length which are offset axially and radially from each other. One of the connecting rods 26 of the pair of connecting rods 26 is connected to a fixed point 27 which is located radially inside the associated retaining sector 14.

[0074] Each elastic membrane 20 comprises, for example, polyurethane so as to be extensible during the movement of the gripping unit 6 associated with the first, second and third positions radially distant from the barrel 4.

[0075] The ring cylinder 24 is, for example, a pneumatic ring cylinder.

[0076] The expansion mechanism 22 of each gripping module 5 includes at least one first pneumatic supply channel 28a, in particular at least first and second pneumatic supply channels 28a, 28b, and more specifically first, second and third pneumatic supply channels 28a, 28b, 28c.

[0077] Each of the first, second and third pneumatic supply routes 28a, 28b, 28c comprises a pneumatic supply pipe extending axially in a spiral inside the barrel 4.

[0078] The first pneumatic supply line 28a supplies the annular cylinder 24.

[0079] The second and third pneumatic supply channels 28b, 28c are located radially inside the first pneumatic supply channel 28a.

[0080] With reference to Figures 3 to 5, each expansion mechanism 22 comprises a rotary selector 30 equipped with first and second rotating rings 32, 34 that are axially adjacent and free to rotate relative to each other. The first and second rotating rings 32, 34 each comprise a plurality of stops 32b, 32c, 34a, 34c, respectively, which are of different axial lengths and are suitable for blocking the movement of the associated ring cylinder 24 according to the angular positions of the rotating rings 32, 34, thus preventing radial movement of the associated gripping unit 6. The first and second rotating rings 32, 34 are suitable for being in first, second, and third angular positions.

[0081] In the first angular position ([Fig.4]), the first and second rotating rings 32, 34 immobilize the associated gripping unit 6 in the first position radially away from the barrel 4 by preventing its expansion beyond the first position radially away from the barrel 4. More specifically, the stops 34a of the second rotating ring 34 of the associated rotary selector 30 block the axial movement of the associated annular cylinder 24 when the first and second rotating rings 32, 34 are in the first angular position.

[0082] In the second angular position ([Fig.3]), the first and second rotating rings 32, 34 immobilize the associated gripping unit 6 in the second position radially away from the barrel 4 by preventing its expansion beyond the second position radially away from the barrel 4. More specifically, the stops 32b of the first rotating ring 32 of the associated rotary selector 30 block the axial movement of the associated annular cylinder 24 when the first and second rotating rings 32, 34 are in the second angular position.

[0083] The stops 32b, 32c, 34a, 34c of the first and second rotating rings 32, 34 are arranged in pairs of stops which are radially opposed to each other in order to distribute circumferentially the forces when blocking the axial movement of the associated annular cylinder 24.

[0084] Each rotary selector 30 includes two springs 36 which each act on one of the first and second rotating rings 32, 34 of the associated rotary selector 30 to return them to the second angular position.

[0085] Each rotary selector 30 includes a pneumatic cylinder 37 which is supplied by the second pneumatic channel 28b, and which is capable of acting on the first rotary ring 32 to position the first and second rotary rings 32, 34 of the associated rotary selector 30 in the first angular position, one of the two springs 36 of the associated rotary selector 30 acting against the movement of this pneumatic cylinder 37 so that the first and second rotary rings 32, 34 of the associated rotary selector 30 return to the second angular position when this pneumatic cylinder 37 is no longer supplied by the second pneumatic channel 28b.

[0086] In the third angular position ([Fig.5]), the first and second rotating rings 32, 34 immobilize the associated gripping unit 6 in the third position radially away from the barrel 4 by preventing its expansion beyond the third position radially away from the barrel 4. More specifically, the stops 32c, 34c of the first and second rotating rings 32, 34 of the associated rotary selector 30 block the axial movement of the associated annular cylinder 24 when the first and second rotating rings 32, 34 are in the third angular position.

[0087] Each rotary selector 30 includes another pneumatic cylinder 38 which is supplied by the third pneumatic channel 28c, and which is capable of acting on the second rotary ring 34 to position the first and second rotary rings 32, 34 of the associated rotary selector 30 in the third angular position, the other of the two springs 36 of the associated rotary selector 30 acting against the movement of this other pneumatic cylinder 38 so that the first and second rotary rings 32, 34 of the associated rotary selector 30 return to the second angular position when this other pneumatic cylinder 38 is no longer supplied by the third pneumatic channel 28c.

[0088] Fig. 6 illustrates one of the gripping modules 5 of the manufacturing drum 2 whose associated gripping unit 6 is immobilized in the second position radially away from the barrel 4. The associated expansion mechanism 22 includes a plurality of stops 39 (also visible in figures 1 and 2) distributed circumferentially which are able to come into axial contact with the stops 32b, 32c, 34a, 34c of the first and second rotating rings 32, 34 according to their angular position so as to limit the axial stroke of the associated annular cylinder 24.

[0089] With reference to Figures 7 and 8, the gripping modules 5 are axially mobile between an axially close position referred to as the "folding" position and an axially distant position referred to as the "conforming" position. These two positions are defined relative to the tire blank 8, which is provided with two ridges 40, two flanks 42, and a vertex 44. In the axially close folding position, the The grasping modules 5 are further apart axially than in the axially distant conformation position. The axial movement of the grasping modules 5 is symmetrical to each other here.

[0090] The tire blank 8 is generally cylindrical in shape. The inter-bead distance d40 of the tire blank 8 is the axial distance between the two beads 40 of the tire blank 8. The inter-sidewall distance d42 of the tire blank 8 is the axial distance between the two sidewalls 42 of the tire blank 8.

[0091] The seat of the tire blank 8 is the inside diameter of the tire blank 8 measured at the heels of the tire blank 8. The outside diameter of the gripping modules 5, in particular of the gripping units 6, when the gripping units 6 are in one of the first, second and third positions radially away from the barrel 4 is equal to the seat of the tire blank 8.

[0092] In the axially close folding position ([Fig.7]), the contact surfaces 16 of the gripping units 6 in the radially distant position of the barrel 4, whose outer diameter corresponds to the seat of the tire blank 8, are able to come into radial contact with the flanks 42 and / or the top 44 of the tire blank 8 by being located axially between the ridges 40 of the tire blank 8. In particular, in the axially close folding position, the axial distance between the axially outer ends of the contact surfaces 16 of the gripping units 6 is less than the inter-ridge distance d40, and here equal to the inter-flank distance d42, of the tire blank 8.Alternatively, in the axially close folding position, the axial distance between the axially outer ends of the contact surfaces 16 of the gripping units 6 could be less than the inter-sidewall distance d42 of the tire blank 8.

[0093] In the axially close folding position, an external folding tool 46 can perform a folding step on the beads 40. During the folding step, the carcass ply and a bead protector, which is notably made of a layer of rubber or composite material, are folded with the external tool 46 around beads located in the beads 40 of the tire blank 8.

[0094] In the axially distant conformation position ([Fig. 8]), the retaining grooves 18 of the gripping units 6 in the radially distant position of the barrel 4, whose outer diameter corresponds to the seat of the tire blank 8, are able to come into radial contact with the ridges 40 of the tire blank 8, the ridges 40 of the tire blank 8 then fitting into the retaining grooves 18 of the gripping units 6. In particular, in the axially distant conformation position, the axial distance between the retaining grooves 18 gripping units 6 is equal to the inter-bead distance d40 of the pneumatic blank 8.

[0095] When the ridges 40 of the pneumatic blank 8 are arranged in the retaining grooves 18 of the gripping units 6, the elastic membranes 20 form in part a sealed chamber 48 by contact with the pneumatic blank 8, the elastic membranes 20 forming the sealed chamber 48 jointly with the pneumatic blank 8, the surfaces of the gripping modules 5 and the surfaces of the barrel 4.

[0096] The manufacturing drum 2 further includes a compressed air passage 50 between a compressed air source external to the manufacturing drum 2 (not shown) and the sealed chamber 48. The compressed air passage 50 allows the circulation of compressed air from the compressed air source to the chamber 48. The sealed chamber 48 is suitable for retaining the compressed air during the shaping of the tire blank 8.

[0097] Fig. 9 represents a method of folding and shaping a tire from the tire blank 8 and the manufacturing drum 2.

[0098] We begin with a step SI of positioning the gripping units 6 in the axially close folding position. During the step SI, the tire blank 8 is also positioned around the barrel 4 so that the contact surfaces 16 of the gripping units 6 are opposite the flanks 42 and / or the top 44 of the tire blank 8 and so that the gripping units 6 are located axially between the ridges 40 of the tire blank 8.

[0099] Then, in a step S2, the gripping units 6 are moved to a position radially away from the barrel 4, the outer diameter of which corresponds to the seat of the tire blank 8, so that the contact surfaces 16 of the gripping units 6 are in contact with the flanks 42 and / or the top 44 of the tire blank 8 and so that the gripping units 6 are located axially between the ridges 40 of the tire blank 8. In step S2, the radial movement of the gripping units 6 is interrupted by the rotary selectors 30, the axial movement of the annular cylinders 24 being interrupted by the stops 32b, 32c, 34a, 34c of the first and second rotary rings 32, 34.

[0100] Next, a step S3 is carried out of folding the pneumatic blank 8 with the external folding tool 46.

[0101] Then, during a step S4, the gripping units 6 are moved into the radially close position of the barrel 4.

[0102] A step S5 is then performed to position the gripping units 6 in their axially distant conformation position. During step S5, the tire blank 8 is also positioned so that the ridges 40 of The pneumatic blanks 8 are opposite the retaining grooves 18 of the gripping units 6.

[0103] Then, in a step S6, the gripping units 6 are moved to a position radially away from the barrel 4, the outer diameter of which corresponds to the seat of the tire blank 8, so that the ridges 40 of the tire blank 8 are in the retaining grooves 18 of the gripping units 6. During step S6, the radial movement of the gripping units 6 is interrupted by the rods in the ridges 40 of the tire blank 8. The force exerted by the retaining grooves 18 of the gripping units 6 on the rods of the ridges 40 of the tire blank 8 then ensures the sealing of the sealed chamber 48.

[0104] Finally, during a step S7, the shaping of the pneumatic blank 8 is carried out. During the shaping, the sealed chamber 48 is pressurized and the gripping units 6 are brought together axially so that the pneumatic blank 8 takes a toroidal shape of a pneumatic.

[0105] Optionally, a rotation is carried out around the axis X-X' of at least one of the ridges 40, in particular of the two ridges 40, of the pneumatic blank 8 relative to the barrel 4 during the axial approach of the gripping modules 5 by sliding of the elastic membrane 20 concerned relative to the retaining sectors 14 of the gripping unit 6 concerned, the pneumatic blank 8 remaining fixed in rotation relative to the elastic membrane 20 concerned.

Claims

1. Demands A manufacturing drum (2) for a tire from a tire blank (8) which is provided with two ribs (40), two sidewalls (42) and a crown (44), the manufacturing drum (2) comprising a barrel (4) extending axially and two tire blank gripping modules (5) which are each movable in axial translation along the barrel (4), each gripping module (5) being provided: - of a gripping unit (6) of the pneumatic blank (8) comprising a plurality of retaining sectors (14) which are arranged circumferentially with respect to each other and which are each provided with a contact surface (16) and a retaining groove (18); - of an expansion mechanism (22) configured to move the gripping unit (6) of said gripping module (5) between a position radially close to the barrel (4) and at least one position radially far from the barrel (4); and - of an elastic membrane (20) disposed in the retaining grooves (18) of the gripping unit (6) of said gripping module (5); manufacturing drum (2) in which the elastic membranes (20) of the gripping modules (5) are intended to partially form a sealed chamber (48) by contact with the pneumatic blank (8), the manufacturing drum (2) further comprising at least one compressed air passage (50) between a compressed air source external to the manufacturing drum (2) and the sealed chamber (48); characterized in that the gripping modules (5) are axially movable at least between: - an axially close position referred to as the "folding" position in which the contact surfaces (16) of the gripping units (6) in said radially distant position from the barrel (4) are able to come into radial contact with one of the flanks (42) and / or the top (44) of the tire blank (8) by being situated axially between the ridges (40) of the tire blank (8), and - an axially distant position referred to as the "conforming" position in which the retaining grooves (18) of the gripping units (6) in said radially distant position of the barrel (4) are suitable for receiving the ridges (40) of the tire blank (8), the axial distance between the retaining grooves (18) of the gripping units (6) being equal to the axial distance between the ridges (40) of the tire blank (8).

2. Manufacturing drum (2) according to claim 1, wherein the expansion mechanism (22) of each gripping module (5) is configured to move the gripping unit (6) of said gripping module (5) between the radially close position of the drum (4) and at least the first and second radially distant positions of the drum (4), and configured to immobilize the gripping unit (6) of said gripping module (5) at each of the first and second radially distant positions of the drum (4).

3. Manufacturing drum (2) according to claim 2, wherein the expansion mechanism (22) of each gripping module (5) is configured to move the gripping unit (6) of said gripping module (5) between the radially close position of the drum (4) and a third radially distant position of the drum (4), and configured to immobilize the gripping unit (6) of said gripping module (5) in the third radially distant position of the drum (4), the diameter of the gripping unit (6) of said gripping module (5) in the third radially distant position of the drum (4) being greater than the diameter of the gripping unit (6) of said gripping module (5) in the second radially distant position of the drum (4).

4. Manufacturing drum (2) according to claim 3, wherein the expansion mechanism (22) of each gripping module (5) comprises a rotary selector (30) provided with rotary rings (32, 34) and stops (32b, 32c, 34a, 34c, 39), said rotary rings (32, 34) being able to be at least in a first immobilization position of the gripping unit (6) of said gripping module (5) in the first position radially away from the drum (4), in a second immobilization position of the gripping unit (6) of said gripping module (5) in the second position radially away from the drum (4), and in a third immobilization position of the gripping unit (6) of said gripping module (5) in the third position radially away from the drum (4).

5. Manufacturing drum (2) according to any one of claims 1 to 4, wherein the elastic membrane (20) of each gripping module (5) comprises polyurethane.

6. Manufacturing drum (2) according to any one of claims 1 to 5, wherein the expansion mechanism (22) of each gripping module (5) comprises an annular cylinder (24) which is movable in axial translation along the barrel (4) and a plurality of connecting rods (26) which convert the axial movement of the annular cylinder (24) into a radial movement communicated to the retaining sectors (14) of the gripping unit (6) of said gripping module (5).

7. Manufacturing drum (2) according to any one of claims 1 to 6, wherein the expansion mechanism (22) of each gripping module (5) comprises a plurality of pneumatic supply channels (28a, 28b, 28c) each comprising a pneumatic supply hose extending axially in a spiral within the drum (4).

8. Method for folding and shaping a tire from a tire blank (8) and a manufacturing drum (2) according to any one of claims 1 to 7, comprising: - positioning each gripping unit (6) in the axially close folding position and positioning the tire blank (8) around the drum (4) so ​​that the sides (42) and / or the top (44) of the tire blank (8) are opposite the contact surfaces (16) of the gripping units (6) and so that the contact surfaces (16) of the gripping units (6) are located axially between the ridges (40) of the tire blank (8);- the movement of each gripping unit (6) into said position radially away from the barrel (4) so ​​that the contact surfaces (16) of the gripping units (6) are in contact with the sides (42) and / or the top (44) of the tire blank (8) by being located axially between the ridges (40) of the tire blank (8); - the folding of the tire blank (8); - the movement of each gripping unit (6) into the position radially closer to the barrel (4);

9. - the positioning of each gripping unit (6) in the axially distant conforming position and the positioning of the pneumatic blank (8) so that the ridges (40) of the pneumatic blank (8) are opposite the retaining grooves (18) of the gripping units (6); - the displacement of each gripping unit (6) in said position radially away from the barrel (4) so ​​that the ridges (40) of the pneumatic blank (8) are in the retaining grooves (18) of the gripping units (6); and - the conformation of the pneumatic blank (8). Folding and shaping method according to claim 8, wherein the shaping of the tire blank (8) comprises pressurizing the sealed chamber (48) and axially bringing together the gripping units (6), a rotation of at least one of the ridges (40) of the tire blank (8) being carried out during the axial bringing together of the gripping units (6) by sliding the elastic membrane (20) concerned relative to the retaining sectors (14) of the gripping unit (6) concerned.

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