Bladder device and method for manufacturing a tire using the bladder device

Abstract

To provide a bladder device that can improve bladder life while ensuring uniformity of tire vulcanization. [Solution] The bladder device 1 includes a support 30 equipped with a first clamp 31 and a second clamp 32, an inner bladder 21 held by the first clamp 31, and an outer bladder 22 held by the second clamp 32. The outer bladder 22 is able to deform in accordance with the expansion of the inner bladder 21 to press against the lumen T1 of an unvulcanized tire T, while being provided to be relatively movable at the contact portion with the inner bladder 21. The outer bladder 22 includes a lumen molding portion 23 facing the lumen T1. The lumen molding portion 23 includes at least a first portion 24 having a first thickness t1 and a second portion 25 having a second thickness t2 smaller than the first thickness t1.

Description

Technical Field

[0001] The present invention relates to a bladder device and a method for manufacturing a tire using the bladder device.

Background Art

[0002] Patent Document 1 below describes a tire vulcanization molding apparatus including a tire vulcanization molding die and a bladder. The bladder is formed in a hollow shape by rubber and is disposed inside the tire vulcanization molding die. Further, when the bladder gauge corresponding to the sidewall portion of the tire is Gs, the bladder gauge corresponding to the central portion in the tire axial direction X of the tread portion of the tire is Gc, and the bladder gauge corresponding to the end portion side in the tire axial direction X of the tread portion of the tire is Gt, then Gs > Gc > Gt.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, the wall thickness of an unvulcanized tire is not constant in the tire radial direction. Therefore, a portion having a large thickness of the unvulcanized tire requires a longer vulcanization time than a portion having a small thickness. However, when the tire vulcanization time is set according to the portion having a large thickness of the unvulcanized tire, the portion having a small thickness tends to be overvulcanized.

[0005] In recent years, to suppress such uneven vulcanization, attempts have been made to change the amount of heat supplied to the unvulcanized tire by changing the thickness of the bladder. Specifically, in the bladder, it has been considered to reduce the thickness of the part facing the thicker part of the unvulcanized tire to supply more heat, while increasing the thickness of the part facing the thinner part of the unvulcanized tire to supply relatively less heat.

[0006] However, bladders with variable thickness as described above have a problem in that, during use, the thinner parts tend to stretch more, leading to concentrated damage in those areas and, consequently, a reduced bladder lifespan.

[0007] This invention was devised in view of the above-described circumstances, and its main objective is to provide a bladder device that can improve bladder life while ensuring uniformity in tire vulcanization. [Means for solving the problem]

[0008] A bladder device comprising a toroidal bladder that expands within the cavity of an unvulcanized tire set in a vulcanizing mold, thereby pressing the unvulcanized tire against the vulcanizing mold, the bladder device comprising a support body having a first clamp and a second clamp, an inner bladder held by the first clamp and supplied with a heating medium inside, and an outer bladder held by the second clamp and positioned outside the inner bladder, wherein the outer bladder is capable of deforming in conjunction with the expansion of the inner bladder to press against the cavity of the unvulcanized tire, and is provided to be relatively movable at the contact portion with the inner bladder, the outer bladder includes a cavity molding portion facing the cavity of the unvulcanized tire, and the cavity molding portion includes at least a first portion having a first thickness and a second portion having a second thickness smaller than the first thickness. [Effects of the Invention]

[0009] By adopting the above configuration, the bladder device of the present invention can improve bladder life while ensuring uniformity of tire vulcanization. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a tire vulcanizing machine including a bladder device according to one embodiment of the present invention. [Figure 2] This is an enlarged view of the left half of Figure 1. [Figure 3] This is an enlarged view of the left half of Figure 1. [Figure 4] This is an enlarged view of the left half of Figure 1. [Figure 5] This is a cross-sectional perspective view of the outer bladder of this embodiment. [Figure 6] This is a cross-sectional perspective view of the inner bladder of this embodiment. [Figure 7] These are unfolded diagrams of the inner and outer bladder. [Figure 8] (A) is an enlarged view of the first upper clamp and the second upper clamp shown in Figure 3, and (B) is an enlarged view of the first lower clamp and the second lower clamp shown in Figure 3. [Figure 9] This is a cross-sectional perspective view of the outer bladder of another embodiment. [Figure 10] This is a cross-sectional perspective view of the outer bladder of yet another embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The drawings contain exaggerations and representations that differ from the actual structural dimensional ratios in order to aid in understanding the present invention. Furthermore, where there are multiple embodiments, the same or common elements are denoted by the same reference numerals throughout the specification, and redundant descriptions are omitted.

[0012] Figure 1 is a cross-sectional view of a tire vulcanizing machine 100 including a bladder device (hereinafter sometimes referred to as "device") 1, which shows one embodiment of the present invention. The tire vulcanizing machine 100 is used in the process of vulcanizing an unvulcanized tire T. An unvulcanized tire T is a cylindrical member in which unvulcanized sidewall rubber and tread rubber are bonded to a base material such as bead wire, carcass, or belt. The unvulcanized tire T that has been vulcanized in the vulcanization process becomes a vulcanized tire (not shown). Thus, an unvulcanized tire T is a tire before vulcanization molding, and is also called a raw cover or green tire. Furthermore, the present invention can be applied to the vulcanization molding of various pneumatic tires, such as those for passenger cars and heavy loads.

[0013] As shown in Figure 1, the unvulcanized tire T is set horizontally inside the tire vulcanizing machine 100 (vulcanizing mold 2). Therefore, the axial direction of the unvulcanized tire T is the same as the vertical (up and down) direction. This specification will be explained based on the horizontally positioned unvulcanized tire T.

[0014] Figure 2 is an enlarged view of the left half of Figure 1. Figure 2 shows a meridional cross-section of an unvulcanized tire T. For convenience, a portion of the bladder 20 (shown in Figure 1), which will be described later, has been removed from Figure 2. As shown in Figure 2, the unvulcanized tire T includes a tread portion Ta, a pair of sidewall portions Tb located on both sides of the tread portion Ta, and bead portions Tc connected to each sidewall portion Tb. The tread portion Ta, sidewall portions Tb, and bead portions Tc of the unvulcanized tire T correspond to the tread portion, sidewall portion, and bead portion of a vulcanized tire, respectively. The unvulcanized tire T also includes a lumen T1 including the inner surface Td and an outer surface Te.

[0015] The thickness ta of the tread portion Ta is formed to be greater than, for example, the thickness tb of each sidewall portion Tb and the thickness tc of each bead portion Tc. The thickness tb of the sidewall portion Tb is formed to be less than, for example, the thickness ta of the tread portion Ta and the thickness tc of the bead portion Tc.

[0016] In the unvulcanized tire T set on the vulcanizer 100 for tires, the pair of sidewall portions Tb consists of an upper sidewall portion Tb1 and a lower sidewall portion Tb2 located below the upper sidewall portion Tb1. Similarly, the bead portion Tc consists of an upper bead portion Tc1 and a lower bead portion Tc2 located below the upper bead portion Tc1.

[0017] As shown in FIG. 1, the tire vulcanizer 100 of the present embodiment includes a bladder device 1 and a vulcanization mold 2. Further, the tire vulcanizer 100 includes, for example, a container 3 for opening and closing the vulcanization mold 2 and a supply means 4 for supplying a heating medium G to the bladder device 1.

[0018] The vulcanization mold 2 includes, for example, an upper mold 6, a lower mold 7, and a tread mold 8 disposed between the upper mold 6 and the lower mold 7. The upper mold 6 is located above the unvulcanized tire T. The lower mold 7 is located below the unvulcanized tire T. The vulcanization mold 2 is operable between an open state (not shown) in which the upper mold 6 and the lower mold 7 are separated in the vertical direction and a closed state Y1 (shown in FIG. 1) in which the upper mold 6 and the lower mold 7 are close to each other in the vertical direction. In the open state of the vulcanization mold 2, the unvulcanized tire T is carried in, and the vulcanized tire is carried out. Further, in the closed state Y1 of the vulcanization mold 2, the unvulcanized tire T is vulcanized and molded.

[0019] The tread mold 8 consists of, for example, a plurality of segments 8A divided in the circumferential direction of the unvulcanized tire T. Each segment 8A is arranged in an annular shape in the circumferential direction around the central axis C1 of the vulcanization mold 2. A tread forming surface that contacts (abuts) the outer surface Te of the tread portion Ta of the unvulcanized tire T is provided on the inner peripheral surface 8a of the segment 8A. In the present embodiment, the tread mold 8 expands and contracts in diameter by the segments 8A moving in the direction away from and closer to the central axis C1. The central axis C1 is in the same direction as the vertical.

[0020] The upper mold 6 includes, for example, an upper side mold 11A that contacts the upper sidewall portion Tb1 (shown in Figure 2) of the unvulcanized tire T, and an upper bead ring 12A that contacts the upper bead portion Tc1. The lower mold 7 includes, for example, a lower side mold 11B that contacts the lower sidewall portion Tb2 of the unvulcanized tire T, and a lower bead ring 12B that contacts the lower bead portion Tc2. In this embodiment, the upper mold 6 and the lower mold 7 are formed in a ring shape. The vulcanizing mold 2 can contact the entire outer surface Te of the unvulcanized tire T.

[0021] Container 3 includes upper and lower plates 13A and 13B, a plurality of holders 14, an actuator ring 15, upper and lower platens 16A and 16B, and a lifting mechanism 17.

[0022] The upper plate 13A in this embodiment holds the upper side mold 11A. The upper plate 13A is, for example, movable in the vertical direction. The lower plate 13B in this embodiment holds the lower side mold 11B.

[0023] Each holder 14 in this embodiment holds each segment 8A. Each holder 14 is positioned, for example, on the outside of the segment 8A. In this embodiment, each holder 14 is arranged in a line in the circumferential direction of the unvulcanized tire T. In the closed state Y1, each holder 14 is formed as an annular body concentric with the central axis C1. In the closed state Y1, each holder 14 is in contact with, for example, the upper and lower plates 13A and 13B.

[0024] In this embodiment, the actuator ring 15 is an annular body that surrounds each holder 14 and is arranged concentrically with the central axis C1. The actuator ring 15 is held on the holder 14 so as to be slidable along the outer surface 14a of the holder 14 by an engaging portion (not shown).

[0025] The upper platen 16A holds, for example, the actuator ring 15. The lower platen 16B holds, for example, the lower plate 13B. In this embodiment, the lower platen 16B is fixed to the table base 18. The upper platen 16A, the lower platen 16B, and the actuator ring 15 have built-in jackets J for accelerating the vulcanization of the unvulcanized tire T.

[0026] In this embodiment, the lifting mechanism 17 includes a first movable table 17A and a second movable table 17B. Each of the first movable table 17A and the second movable table 17B is held so as to be able to move up and down in the vertical direction by, for example, a well-known cylinder structure drive unit (not shown). By raising and lowering the first movable table 17A, the actuator ring 15 and the upper platen 16A can be moved in the vertical direction. By raising and lowering the actuator ring 15 by the first movable table 17A, the holder 14 and the segment 8A fixed to the holder 14 are moved radially (near and far from the central axis C1) and vertically of the unvulcanized tire T. By raising and lowering the second movable table 17B, the upper plate 13A and the upper mold 6 can be moved in the vertical direction. By moving the lifting mechanism 17, the vulcanizing mold 2 is brought into a closed state Y1 or the open state. Thus, the container 3 in this embodiment employs a well-known structure. Furthermore, container 3 is not limited to this configuration and can take on various structures.

[0027] The supply means 4 includes, for example, a supply source 4a that generates a heating medium G, a supply port (not shown) located inside the vulcanization mold 2, and a flow path 4b connecting the supply source 4a and the supply port. The supply source 4a is located, for example, outside the container 3. The heating medium G is preferably a mixture of high-temperature, high-pressure steam and an inert gas such as nitrogen gas. The supply source 4a is preferably a combination of a boiler and an inert gas generator.

[0028] The bladder apparatus 1 includes a bladder 20 and a support 30 that supports the bladder 20. The bladder 20 is, for example, an elastic body made of rubber. The bladder 20 expands into a toroidal shape within the lumen T1 of the unvulcanized tire T by the heating medium G. This allows the bladder 20 to press the unvulcanized tire T against the vulcanization mold 2. The bladder 20 can also accelerate vulcanization by supplying heat from the heating medium G to the unvulcanized tire T. Furthermore, the bladder 20 shrinks when the heating medium G is removed (as shown in Figure 4).

[0029] Figures 3 and 4 are enlarged views of the left half of Figure 1. Figure 3 shows the bladder 20 after expansion. Figure 4 shows the bladder 20 before expansion (after contraction). For convenience, the unvulcanized tire T during vulcanization molding is shown by a dashed line in Figure 4. As shown in Figures 3 and 4, the bladder 20 includes an inner bladder 21 into which a heating medium G is supplied, and an outer bladder 22 positioned outside the inner bladder 21. In other words, during vulcanization molding, the inner bladder 21 needs to expand due to the heating medium G and maintain the internal pressure caused by the heating medium G. On the other hand, the outer bladder 22 is not supplied with the heating medium G. Therefore, during vulcanization molding, the outer bladder 22 can deform (expand) in accordance with the expansion of the inner bladder 21 and press against the lumen T1 (lumen surface Td) of the unvulcanized tire T, and does not need to hold the heating medium G.

[0030] The outer bladder 22 of this embodiment includes a lumen molding section 23 that faces (contacts with the lumen surface Td) the lumen T1 of the unvulcanized tire T. The lumen molding section 23 includes at least a first section 24 and a second section 25. The first section 24 has a first thickness t1. The second section 25 has a second thickness t2 that is smaller than the first thickness t1. Such a bladder device 1 can position the first section 24 against the thinner portion of the unvulcanized tire T and the second section 25 against the thicker portion of the unvulcanized tire T, thereby enabling uniform vulcanization of the unvulcanized tire T. The lumen molding section 23 of this embodiment contacts the entire lumen surface Td during vulcanization molding. The first thickness t1 and the second thickness t2 are the thickness of the outer bladder 22 when new and shrunk.

[0031] The first part 24 and the second part 25 are adjacent, for example, in the radial direction f (shown in Figure 3) of the unvulcanized tire T. This allows for the placement of the first part 24 or the second part 25 of appropriate thickness to portions of the unvulcanized tire T with different thicknesses in the radial direction f. This further improves the uniformity of tire vulcanization. In this specification, the radial direction f is the direction along the shape of the unvulcanized tire T, from the equator C of the unvulcanized tire T to the bead portions Tc on both sides, in the tire meridian cross-section of the unvulcanized tire T.

[0032] The second portion 25 is provided, for example, at a position that presses against the tread portion Ta of the unvulcanized tire T. The first portion 24 is provided, for example, at a position that presses against the sidewall portion Tb of the unvulcanized tire T. This further improves the uniformity of tire vulcanization. The first portion 24 includes an upper first portion 24a that presses against the upper sidewall portion Tb1 of the unvulcanized tire T, and a lower first portion 24b that presses against the lower sidewall portion Tb2. In this embodiment, the first thickness t1 of the upper first portion 24a is formed to be the same as the first thickness t1 of the lower first portion 24b.

[0033] The difference between the first thickness t1 and the second thickness t2 (t1-t2) is preferably 1 mm or more, more preferably 2 mm or more, preferably 8 mm or less, and more preferably 5 mm or less. Since the difference (t1-t2) is 1 mm or more and 8 mm or less, suitable heat can be supplied to parts of the unvulcanized tire T with different thicknesses, thereby further improving the uniformity of tire vulcanization of the unvulcanized tire T.

[0034] While not particularly limited, the second thickness t2 is preferably 0.5 mm or more, more preferably 1.0 mm or more, more preferably 4.0 mm or less, and more preferably 3.0 mm or less.

[0035] The inner molded portion 23 of the outer bladder 22 is not limited to consisting only of the first portion 24 and the second portion 25, but may consist of multiple portions of different thicknesses, or the thickness may change continuously, for example, along the radial direction f of the unvulcanized tire T.

[0036] Figure 5 is a cross-sectional perspective view of the outer bladder 22. As shown in Figure 5, in this embodiment, the lumen molding section 23 is provided with at least one opening k. Multiple openings k are provided in the lumen molding section 23, for example. The openings k are, for example, vent holes with an inner diameter d of 0.3 to 2.0 mm. Such openings k allow the gas between the outer bladder 22 and the unvulcanized tire T to move between the outer bladder 22 and the inner bladder 21 during vulcanization molding. Openings k forming vent holes are provided in both, for example, the first section 24 and the second section 25 (shown in Figure 4). If no openings k are provided, a vent line BL may be provided on the outer peripheral surface 22e of the outer bladder 22 (shown in Figure 9). The outer bladder 22 may also be configured without openings k or vent line BL (not shown). In this embodiment, since the outer bladder 22 has a first portion 24 and a second portion 25, it can expand during vulcanization molding in a way that allows the gas between the unvulcanized tire T and the outer bladder 22 to escape smoothly.

[0037] As shown in Figure 4 or Figure 5, the outer bladder 22 further includes, for example, an upper edge 27a and a lower edge 27b located below the upper edge 27a. The upper edge 27a and the lower edge 27b are connected to the lumen molding 23. Each of the upper edge 27a and the lower edge 27b includes a first flange portion F1. Each of the upper edge 27a and the lower edge 27b is formed in an L-shape in cross-section. The ends of each of the upper edge 27a and the lower edge 27b extend axially inward to the unvulcanized tire T.

[0038] Figure 6 is a cross-sectional perspective view of the inner bladder 21. As shown in Figure 4 or Figure 6, the inner bladder 21 of this embodiment includes a main body 28 that presses against the lumen molding portion 23 of the outer bladder 22. The main body 28 has a third thickness t3 which is substantially constant. The "constant thickness" means that, when new and shrunk, the difference between the maximum and minimum thickness of the main body 28 that contacts the lumen molding portion 23 is 0.5 mm or less.

[0039] Furthermore, the third thickness t3 is preferably 2 mm or more, more preferably 3 mm or more, preferably 7 mm or less, and more preferably 5 mm or less. Such an inner bladder 21 can expand smoothly when the heating medium G is supplied, and can also improve durability and extend the bladder life. The third thickness t3 is also the thickness when new and shrunk.

[0040] The inner bladder 21 further includes, for example, an upper edge 29a and a lower edge 29b located below the upper edge 29a. The upper edge 29a and the lower edge 29b are connected to the main body 28. Each of the upper edge 29a and the lower edge 29b includes a second flange portion F2. Each of the upper edge 29a and the lower edge 29b is formed in a T-shape in cross-section. The ends of each of the upper edge 29a and the lower edge 29b extend toward both sides (up and down) in the axial direction of the unvulcanized tire T.

[0041] As shown in Figure 6, multiple vent lines BL are provided on the outer circumferential surface 21e of the inner bladder 21. The vent lines BL are ventilation lines for discharging gas that has entered the interface between the inner bladder 21 and the outer bladder 22 to the outside. The vent lines BL are formed, for example, to connect the upper edge 29a and the lower edge 29b of the inner bladder 21. It is desirable that the vent lines BL extend inclined with respect to the circumferential direction of the unvulcanized tire T.

[0042] A vent line BL is, for example, a groove. The number, width W, and depth D of the vent lines BL should be determined in a way that balances smooth gas discharge with the durability of the inner bladder 21. While not particularly limited, the width W of the vent line BL should be, for example, about 0.5 to 1.0 mm. The depth D of the vent line BL should also be, for example, about 0.5 to 1.0 mm.

[0043] Figure 7 is an exploded view of the inner bladder 21 and the outer bladder 22. As shown in Figure 7, it is desirable that the vent line BL located on the outer peripheral surface 21a of the inner bladder 21 communicates with the opening k of the outer bladder 22. This allows the gas between the outer bladder 22 and the unvulcanized tire T to be smoothly discharged to the outside through the vent line BL.

[0044] The outer bladder 22 is preferably made of silicone rubber or fluororubber. The inner bladder 21 is made of butyl rubber. Silicone rubber or fluororubber are rubbers with high release properties. As a result, when the heating medium G is supplied and the inner bladder 21 expands, the outer bladder 22 becomes movable relative to the inner bladder 21 at the contact point and maintains high slipperiness against the unvulcanized tire T. Therefore, stretching of only the second portion 25 is suppressed. Also, when the inner bladder 21 contracts, the outer bladder 22 becomes movable relative to the inner bladder 21 at the contact point and can be smoothly released from the unvulcanized tire T. Therefore, damage due to wrinkle formation on the outer bladder 22 and inner bladder 21 is suppressed. Furthermore, butyl rubber is highly resistant to corrosion from heat and exhibits high durability. Such a bladder 20 has an excellent bladder life. Note that the outer bladder 22 may also be made of butyl rubber.

[0045] Silicone rubber is a type of silicone resin that exhibits rubber-like properties, and is also called silicon rubber. Fluororubber is a rubber containing fluorine, and its copolymer composition has CF bonds (fluorine bonds). Known fluororubbers include VDF-HFP copolymer (where VDF: vinylidene fluoride, HFP: hexafluoropropylene), VDF-HFP-TFE copolymer (where VDF: vinylidene fluoride, HFP: hexafluoropropylene, TFE: tetrafluoroethylene), and VDF-PMVE-TFE copolymer (where VDF: vinylidene fluoride, PMVE: perfluoromethyl vinyl ether, TFE: tetrafluoroethylene). Silicone rubber and fluororubber may contain appropriate additives to achieve the required functions.

[0046] Furthermore, butyl rubber can be a synthetic rubber obtained by copolymerizing isobutylene with several percent isoprene. Butyl rubber may also contain appropriate additives to achieve the required functionality.

[0047] As shown in Figure 3, the support 30 comprises a first clamp 31 for holding the inner bladder 21 and a second clamp 32 for holding the outer bladder 22. The support 30 further includes a base 33 (shown in Figure 1) extending upward from the table base 18 and a center post 34 that is movable up and down relative to the base 33. The central axis of the center post 34 is concentric with the central axis C1 (shown in Figure 1) of the vulcanizing mold 2. The first clamp 31 and the second clamp 32 are supported by the center post 34.

[0048] The first clamp 31 includes a first upper clamp 31a capable of gripping the upper edge 27a (shown in Figure 4) of the inner bladder 21, and a first lower clamp 31b capable of gripping the lower edge 27b of the inner bladder 21. The first lower clamp 31b is positioned below the first upper clamp 31a. The second clamp 32 includes a second upper clamp 32a capable of gripping the upper edge 29a (shown in Figure 4) of the outer bladder 22, and a second lower clamp 32b capable of gripping the lower edge 29b of the outer bladder 22. The second lower clamp 32b is positioned below the second upper clamp 32a.

[0049] Figure 8(A) is an enlarged view of the first upper clamp 31a and the second upper clamp 32a shown in Figure 3. As shown in Figure 8(A), the first upper clamp 31a includes a disc-shaped first upper base 36 and a first upper sub-part 37 positioned above the first upper base 36. The first upper base 36 is held by the center post 34. The first upper sub-part 37 is formed, for example, in an annular shape. By joining the first upper base 36 and the first upper sub-part 37, a first upper recess 39 is formed for fitting the upper edge 29a of the inner bladder 21. The first upper base 36 and the first upper sub-part 37 are fastened together by a bolt Bo, thereby firmly holding the upper edge 29a (second flange portion F2) to the first upper clamp 31a while also making it detachable.

[0050] Figure 8(B) is an enlarged view of the first lower clamp 31b and the second lower clamp 32b shown on the left side in Figure 3. As shown in Figure 8(B), the first lower clamp 31b includes a disc-shaped first lower base 41 and a first lower sub-part 42 positioned below the first lower base 41. The first lower base 41 is held by the center post 34. The first lower sub-part 42 is formed, for example, in an annular shape. By joining the first lower base 41 and the first lower sub-part 42, a first lower recess 43 is formed for fitting the lower edge 29b of the inner bladder 21. The first lower base 41 and the first lower sub-part 42 are fastened together by a bolt Bo, so that the lower edge 29b (second flange portion F2) is firmly held by the first lower clamp 31b and is also detachable. The first upper clamp 31a and the first lower clamp 31b are not limited to this configuration.

[0051] As shown in Figure 8(A), the second upper clamp 32a includes a first upper sub-part 37 and a first retaining part 45 positioned above the first upper sub-part 37. The upper surface 37a of the first upper sub-part 37 has a second upper recess 46 formed therein for fitting the upper edge 27a (first flange part F1) of the outer bladder 22. The first retaining part 45 includes a contact surface 51 that contacts the upper bead ring 12A. The first retaining part 45 is fixed, for example, to the upper end of the center post 34 with bolts Bo. The outer bladder 22, which is not filled with the heating medium G, is fixed with fewer bolts Bo than the bolts Bo that hold the inner bladder 21. The upper second clamp 32a is also provided with an upper exhaust groove 53 and an upper exhaust hole 54 for discharging the gas between the inner bladder 21 and the outer bladder 22 to the outside of the vulcanization mold 2. The upper exhaust groove 53 is provided on the surface of the first upper sub-part 37 facing the inner lumen T1. The upper exhaust port 54 includes a first upper exhaust port 54A that is connected to the upper exhaust groove 53 and extends inside the first upper sub-part 37, and a second upper exhaust port 54B that extends vertically from the first retaining portion 45. The gas between the inner bladder 21 and the outer bladder 22 is discharged from the upper exhaust groove 53 through the first upper exhaust port 54A and the second upper exhaust port 54B to the outside of the vulcanization mold 2.

[0052] As shown in Figure 8(B), the second lower clamp 32b includes a first lower sub-part 42 and a second retaining part 48 positioned below the first lower sub-part 42. The lower surface 42a of the first lower sub-part 42 has a second lower recess 49 formed therein for fitting the lower edge 27b (first flange part F1) of the outer bladder 22. The second retaining part 48 includes a contact surface 52 that contacts the lower bead ring 12B. With these first clamps 31 and 2 clamps 32 (shown in Figure 3), the outer bladder 22 is easier to replace than the inner bladder 21. The second retaining part 48 and the lower bead ring 12B are fixed together, for example, with bolts (not shown). The first lower sub-part 42 is also provided with a lower exhaust groove 55 and a lower exhaust hole 56 for discharging the gas between the inner bladder 21 and the outer bladder 22 to the outside of the vulcanization mold 2. The lower exhaust groove 55 is provided on the surface of the first lower sub-part 42 facing the inner lumen T1. The lower exhaust hole 56 is connected to the lower exhaust groove 55 and extends inside the first lower sub-part 42. The gas between the inner bladder 21 and the outer bladder 22 is discharged to the outside of the vulcanization mold 2 through the lower exhaust groove 55 and the lower exhaust hole 56.

[0053] Figure 9 is a cross-sectional perspective view of the outer bladder 22 of another embodiment. Generally, when the heating medium G (shown in Figure 1) is steam, during the vulcanization process, water Wa, which is liquefied steam, may accumulate in the lower first portion 24b. In this state, the lower sidewall portion Tb2 (shown in Figure 2) receives less heat from the heating medium G compared to the upper sidewall portion Tb1, and uniformity of tire vulcanization between the lower sidewall portion Tb2 and the upper sidewall portion Tb1 may not be achieved. For this reason, as shown in Figure 9, in the outer bladder 22, the first thickness ty of the lower first portion 24b is formed to be smaller than the first thickness tx of the upper first portion 24a. This makes it possible to achieve uniformity of tire vulcanization between the lower sidewall portion Tb2 and the upper sidewall portion Tb1. In this embodiment, it is desirable that a plurality of vent lines BL are provided on the outer peripheral surface 22e of the outer bladder 22.

[0054] Figure 10 is a cross-sectional perspective view of the outer bladder 22 of another embodiment. As shown in Figure 10, in the outer bladder 22 of this embodiment, the opening k of the inner molding portion 23 is formed with a larger opening area than the vent hole (shown in Figure 5). Multiple openings k are provided in the circumferential direction of the unvulcanized tire T in this embodiment. The openings k are also provided at positions facing the tread portion Ta (shown in Figure 2) of the unvulcanized tire T. Such openings k promote the vulcanization of the thicker tread portion Ta, contributing to the uniform vulcanization of the unvulcanized tire T. Such openings k are configured as a second portion 25 (second thickness t2 is 0 mm). The first portion 24 is formed between adjacent openings k in the circumferential direction of the unvulcanized tire T.

[0055] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be implemented in various modified forms.

[0056] [Note] The present invention includes the following embodiments.

[0057] [Invention 1] A bladder device comprising a toroidal bladder that expands within the cavity of an unvulcanized tire set in a vulcanizing mold, thereby pressing the unvulcanized tire against the vulcanizing mold, A support equipped with a first clamp and a second clamp, An inner bladder, which is held by the first clamp and has a heating medium supplied inside, Includes an outer bladder, which is held by the second clamp and positioned outside the inner bladder, The outer bladder is deformed in accordance with the expansion of the inner bladder and can press against the inner cavity of the unvulcanized tire, while the contact portion with the inner bladder is provided to be movably relative to it. The outer bladder includes a cavity molding portion facing the cavity of the unvulcanized tire, The internal molded portion includes at least a first portion having a first thickness and a second portion having a second thickness smaller than the first thickness. Bladder device. [2nd Invention] The bladder device according to the present invention 1, wherein the second part and the first part are adjacent in the radial direction of the unvulcanized tire. [Invention 3] The bladder device according to the present invention 1 or 2, wherein the second part is provided at a position for pressing the tread portion of the unvulcanized tire. [4th Invention] The first part is provided in a position for pressing the sidewall portion of the unvulcanized tire, as described in any one of inventions 1 to 3. [5th ​​Invention] The bladder device according to any one of inventions 1 to 4, wherein the difference between the first thickness and the second thickness is 1 to 8 mm. [Invention 6] The vulcanizing mold includes an upper mold and a lower mold. The first portion includes an upper first portion that presses against the sidewall portion on the upper mold side of the unvulcanized tire, and a lower first portion that presses against the sidewall portion on the lower mold side of the unvulcanized tire. The bladder device according to any one of inventions 1 to 5, wherein the lower first portion has a thickness smaller than the upper first portion. [7th Invention] The inner bladder includes a main body that presses against the inner lumen molding portion of the outer bladder. The bladder device according to any one of inventions 1 to 6, wherein the main body portion has a third thickness that is substantially constant. [8th Invention] The bladder device according to the present invention, wherein the third thickness is 2 to 7 mm. [Invention 9] The inner bladder is made of butyl rubber, The bladder device according to any one of claims 1 to 8 of the present invention, wherein the outer bladder is formed of silicone rubber or fluororubber. [Invention 10] The bladder device according to any one of inventions 1 to 9, wherein the lumen forming portion has at least one opening formed therein. [Invention 11] Multiple vent lines are provided on the outer circumferential surface of the inner bladder. The bladder device according to the present invention 10, wherein the vent line is in communication with the opening. [Invention 12] A method for manufacturing a tire, comprising the step of vulcanizing the unvulcanized tire using a bladder device described in any one of the present inventions 1 to 11. [Explanation of Symbols]

[0058] 1. Bladder device 21 Inner bladder 22 Outer bladder 23 Inner cavity molding part 24 Part 1 25 Part 2 30 Support 31. First clamp 32 Second Clamp T Unvulcanized Tires T1 lumen t1 First thickness t2 Second thickness

Claims

1. A bladder device comprising a toroidal bladder that expands within the cavity of an unvulcanized tire set in a vulcanizing mold, thereby pressing the unvulcanized tire against the vulcanizing mold, A support equipped with a first clamp and a second clamp, An inner bladder, which is held by the first clamp and has a heating medium supplied inside, Includes an outer bladder, which is held by the second clamp and positioned outside the inner bladder, The outer bladder is deformed in accordance with the expansion of the inner bladder and can press against the inner cavity of the unvulcanized tire, while the contact portion with the inner bladder is provided to be movably relative to it. The outer bladder includes a cavity molding portion facing the cavity of the unvulcanized tire, The internal molded portion includes at least a first portion having a first thickness and a second portion having a second thickness smaller than the first thickness. Bladder device.

2. The bladder device according to claim 1, wherein the second portion and the first portion are adjacent in the radial direction of the unvulcanized tire.

3. The bladder device according to claim 1, wherein the second portion is provided at a position for pressing the tread portion of the unvulcanized tire.

4. The bladder device according to claim 1, wherein the first portion is provided in a position to press against the sidewall portion of the unvulcanized tire.

5. The bladder device according to claim 1, wherein the difference between the first thickness and the second thickness is 1 to 8 mm.

6. The vulcanizing mold includes an upper mold and a lower mold. The first portion includes an upper first portion that presses against the sidewall portion on the upper mold side of the unvulcanized tire, and a lower first portion that presses against the sidewall portion on the lower mold side of the unvulcanized tire. The bladder device according to claim 1, wherein the lower first portion has a thickness smaller than the upper first portion.

7. The inner bladder includes a main body that presses against the inner lumen molding portion of the outer bladder. The bladder device according to any one of claims 1 to 6, wherein the main body portion has a third thickness that is substantially constant.

8. The bladder device according to claim 7, wherein the third thickness is 2 to 7 mm.

9. The inner bladder is made of butyl rubber, The bladder device according to any one of claims 1 to 6, wherein the outer bladder is formed of silicone rubber or fluororubber.

10. The bladder device according to any one of claims 1 to 6, wherein the lumen forming portion has at least one opening formed therein.

11. Multiple vent lines are provided on the outer circumferential surface of the inner bladder. The bladder device according to claim 10, wherein the vent line communicates with the opening.

12. A method for manufacturing a tire, comprising the step of vulcanizing the unvulcanized tire using a bladder device described in any one of claims 1 to 6.

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