Bladder for vulcanization molding and method for manufacturing a tire

Abstract

To improve an appearance quality of a tire.SOLUTION: A vulcanization molding bladder 22, which molds an inner surface of a low cover 50, includes: a pair of bead sections 52; a pair of sidewall sections 54 extending from the bead sections 52; and a tread section 56 connecting the pair of sidewall sections 54. The vulcanization molding bladder 22 includes: a cylindrical body 22a; and ring-shaped flanges 22b provided at each end of the body 22a. A fiber 22c is included in at least a portion of the body 22a that is in contact with the inner surface of the pair of sidewall sections 54.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a bladder for vulcanization molding and a method for manufacturing a tire.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2016-93953 discloses a bladder for tire vulcanization that is disposed inside a raw tire (referred to as a "green tire" in the same publication) and expands to hold the raw tire. When such a bladder for tire vulcanization holds the raw tire, a portion corresponding to the region from the belt end of the raw tire toward the side portion is configured by a deformation suppression portion in which the amount of deformation is suppressed more than other portions. The deformation suppression portion is configured by adhering a reinforcing body to the inner peripheral surface. The reinforcing body is made of rubber like the bladder body. When such a bladder for tire vulcanization is expanded to hold the raw tire, the expansion of the bladder body is suppressed by the reinforcing body by the deformation suppression portion, and the region from the belt end of the raw tire toward the side portion does not deform more than necessary. Therefore, a part of the raw tire is not bitten into the mold. As a result, it is said that it is possible to surely prevent the mold from deteriorating due to biting and the rubber that has fallen off from adhering to the surface of the raw tire to be vulcanized next and becoming a defective product.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, steps may occur in the sidewall portion where sheet-like rubber materials are overlapped. And steps may remain in the sidewall portion of the tire after vulcanization molding. Such a phenomenon was observed in the prototypes made by the inventor. The sidewall portion is, for example, decorated such as having characters inscribed thereon, and has a great impact on the appearance quality.

Means for Solving the Problems

[0005] In the present disclosure, a vulcanization molding bladder for molding the inner surface of a local cover has a pair of bead portions, a pair of sidewall portions extending from the bead portions, and a tread portion connecting the pair of sidewall portions. The vulcanization molding bladder has a cylindrical body portion and ring-shaped flange portions provided at both ends of the body portion, respectively. At least a part of the portion of the body portion that abuts against the inner surface of the pair of sidewall portions contains fibers. By using a vulcanization molding bladder having such a configuration, the appearance quality of the tire after vulcanization can be improved.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0007] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the following embodiments. Each drawing is schematically drawn and does not necessarily reflect the actual object. Also, each drawing is only an example and does not limit the present disclosure unless otherwise specified. Further, members and parts having the same function are appropriately given the same reference numerals, and redundant explanations are omitted. Also, the notation "A~B" indicating a numerical range means "A or more and B or less" unless otherwise specified.

[0008] FIG. 1 is a cross-sectional view schematically showing a part of a tire vulcanizing apparatus 10. The tire can be manufactured by vulcanizing a local cover 50 with the vulcanizing apparatus 10.

[0009] <Local cover 50> The local cover 50 is obtained by bonding and preliminarily molding the members constituting the tire. FIG. 2 is a schematic view of the local cover 50 and the vulcanization molding bladder 22. In FIG. 2, the local cover 50 and the vulcanization molding bladder 22 in contact with the inner surface of the local cover 50 during vulcanization are shown. In FIG. 2, a cross-section along the axial direction of the central axis of the local cover 50 is shown. Note that in FIG. 2, the hatching indicating the cross-section is omitted. FIG. 3 is a schematic view of the local cover 50. In FIG. 3, a view seen from the outside in the radial direction of the local cover 50 is shown. FIG. 4 is a cross-sectional view showing a joint 54b of the sidewall portion 54. In FIG. 4, a cross-section along the circumferential direction of the sidewall portion 54 including the joint 54b is shown.

[0010] As shown in FIG. 2, in this embodiment, the local cover 50 has a pair of bead portions 52, a pair of sidewall portions 54 extending from the bead portions 52, and a tread portion 56 connecting the pair of sidewall portions 54. The bead portion 52 is a portion that constitutes the radially inner end of the vulcanized tire. The bead portion 52 contains a bead core 52a and an apex 52b inside. The bead portion 52 is annularly provided at the radially inner end of the local cover 50. The sidewall portion 54 is a portion that constitutes the side surface of the vulcanized tire. The sidewall portion 54 extends from the bead portion 52 toward the radially outer end of the local cover 50. The tread portion 56 is a portion that constitutes the portion in contact with the road surface in the tire after vulcanization. The tread portion 56 extends axially inward from the radially outer ends of the pair of sidewall portions 54. The tread portion 56 is cylindrical.

[0011] The local cover 50 includes a carcass 50a inside that forms the skeleton of the local cover 50. On the outer surface of the carcass 50a, in the tread portion 56, a belt 50c that reinforces the tread portion 56 is disposed. The carcass 50a has an annular bead core 52a and an apex 52b that extends radially outward along the carcass 50a from the annular bead core 52a in the bead portion 52. In the bead portion 52, at the radially inner end, the bead core 52a and the apex 52b are wound into and covered by the carcass 50a.

[0012] The local cover 50 includes an inner liner 50b that covers the inner surface, and sidewall rubber 54a and tread rubber 56a that cover the outer surface. In the tread portion 56, the outer side is covered by the tread rubber 56a. In the sidewall portion 54 and the bead portion 52, the outer side is covered by the sidewall rubber 54a.

[0013] The sidewall rubber 54a covering the sidewall portion 54 and the bead portion 52 is formed in a sheet shape. In this embodiment, the sidewall rubber 54a is a single sheet of rubber. As shown in FIG. 3, the sidewall rubber 54a is formed by being wound once in the circumferential direction of the local cover 50. Therefore, a joint 54b in which the sidewall rubber 54a slightly overlaps is formed in the sidewall portion 54 (see FIG. 4).

[0014] <Vulcanizing device 10> As shown in FIG. 1, the vulcanizing device 10 includes a bladder center mechanism 20 and a mold 30. The vulcanizing device 10 is a device for vulcanizing and molding the local cover 50. The vulcanizing device 10 introduces a high-temperature fluid from the inside of the vulcanizing bladder 22 provided in the bladder center mechanism 20 to expand it, and presses the local cover 50 against the mold 30. Thereby, the local cover 50 is heated and pressurized.

[0015] <Mold 30> The mold 30 includes a first side mold 32, a second side mold 34 facing the first side mold 32, and a tread mold 36. When the local cover 50 is pressed against the mold 30, the outer shape of the vulcanized tire is formed. The bead portion 52 and the sidewall portion 54 are pressed against the first side mold 32 and the second side mold 34. The tread portion 56 is pressed against the tread mold 36.

[0016] During vulcanization, the local cover 50 is set on the second side mold 34. A cylinder (not shown) is attached to the first side mold 32 and is configured to be able to move up and down. The first side mold 32 is configured to move up when the local cover 50 is set on the second side mold 34 and move down during vulcanization. The tread mold 36 is composed of a plurality of molds. The tread mold 36 is configured to open and close in accordance with the movement up and down of the first side mold 32 by, for example, a guide attached to the first side mold 32. That is, before vulcanization, the tread mold 36 is in an open state, but when the first side mold 32 moves down during vulcanization, the tread mold 36 is closed in conjunction with it.

[0017] <Bladder center mechanism 20> The bladder center mechanism 20 includes a bladder 22 for vulcanization molding (hereinafter also simply referred to as "bladder"), a pair of clamp rings 27a and 27b, and a center post 26. The bladder 22 is formed in a cylindrical shape, and both ends (flange portions 22b) are attached to the disk-shaped clamp rings 27a and 27b, respectively. The upper clamp ring 27a is attached to the upper part of the center post 26. The lower clamp ring 27b has a through hole 27b1 through which the center post 26 passes.

[0018] The center post 26 is configured to be able to move up and down by a cylinder (not shown). Thereby, the distance between the pair of clamp rings 27a and 27b can be changed. During vulcanization, the center post 26 moves down, and the distance between the clamp rings 27a and 27b becomes narrower in accordance with the width of the local cover 50. After vulcanization, the center post 26 moves up, and the distance between the clamp rings 27a and 27b becomes wider. The center post 26 is configured to move up and down in conjunction with the movement up and down of the first side mold 32.

[0019] The space inside the bladder 22 is independent of the space outside the bladder 22. Further, the bladder center mechanism 20 is configured to be able to introduce a high-temperature fluid into the space inside the bladder 22 during vulcanization. In this embodiment, the high-temperature fluid can be introduced from the through-hole 27b1 of the clamp ring 27b toward the space inside the bladder 22.

[0020] <Vulcanization bladder 22> The vulcanization bladder 22 forms the inner surface of the local cover 50. FIG. 5 is a schematic diagram showing the vulcanization bladder 22. In FIG. 5, the portion containing the fiber 22c, the direction of the first fiber 22c1, and the direction of the second fiber 22c2 are schematically shown. The vulcanization bladder 22 has a body portion 22a and ring-shaped flange portions 22b provided at both ends of the body portion 22a, respectively.

[0021] The flange portion 22b is a portion that is respectively attached to the clamp rings 27a and 27b. The body portion 22a is in a barrel shape whose circumferential length gradually increases toward the inside from the flange portion 22b. The bladder 22 is an elastic body made of rubber. As the elastic body made of rubber used for the bladder 22, conventionally known ones can be adopted without particular limitation, and are not particularly limited. When a high-temperature fluid is introduced into the bladder 22 by the bladder center mechanism 20 during vulcanization, the body portion 22a expands. Thereby, the local cover 50 is pressed against the mold 30 while being heated and vulcanized.

[0022] The bladder 22 contains fibers 22c in at least a part of the portion of the body portion 22a that abuts against the inner surfaces of the pair of side wall portions 54. In this embodiment, the fibers 22c are continuously included in the circumferential direction at the portion of the body portion 22a that abuts against the inner surfaces of the pair of side wall portions 54. The portion containing the fibers 22c has a higher elastic strength than the portion not containing the fibers 22c.

[0023] In this embodiment, nylon fibers are used as the fibers 22c. The fibers 22c included in the body portion 22b are not particularly limited. As the fibers 22c, for example, fibers such as polyester, aramid, and rayon can be used. Nylon fibers can be preferably used as the fibers 22c. By including high-strength nylon fibers in the bladder 22, the local cover 50 can be pressed more strongly against the mold 30. The thickness of the fibers and the like are not particularly limited, but for example, fibers having a diameter of about 0.4 to 1.0 mm can be used.

[0024] Incidentally, as described above, the side wall portion 54 of the local cover 50 is composed of a sheet-like side wall rubber 54a (see FIG. 3). A joint 54b in which the ends of the sheet-like side wall rubber 54a slightly overlap is formed in the side wall portion 54. The joint 54b is thicker than other portions of the side wall portion 54. In the findings of the present inventor, there is a concern that if the joint is not sufficiently crushed during vulcanization, the joint will remain in a raised state even after vulcanization. In this way, the remaining of the joint in a raised state is likely to occur, for example, in a large tire with a thick side wall portion such as a tire for an SUV (Sport Utility Vehicle). Since the side wall portion constitutes the side surface of the tire after vulcanization, the influence of the raised joint on the appearance quality is greater compared to other parts.

[0025] As shown in FIG. 5, the fiber 22c is formed in a mesh shape by a plurality of first fibers 22c1 extending parallel to the first direction D1 and a plurality of second fibers 22c2 extending parallel to a second direction D2 different from the first direction D1. The first fibers 22c1 and the second fibers 22c2 are inclined at about 50 degrees to 60 degrees with respect to the circumferential direction of the body portion 22a. The first fibers 22c1 and the second fibers 22c2 are inclined in opposite directions from each other in the circumferential direction of the body portion 22a. The angle of the fiber 22c with respect to the circumferential direction of the body portion 22a is not particularly limited. The angle of the fiber 22c may be, for example, 40 degrees or more, and preferably 50 degrees or more. Also, the angle of the fiber 22c may be 70 degrees or less, and preferably 60 degrees or less. Thus, since the fiber 22c is inclined with respect to the circumferential direction of the body portion 22a, the bladder 22 can be pressed more strongly.

[0026] The fiber 22c is included inside the body portion 22a of the bladder 22. FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5. In FIG. 6, a portion of the bladder 22 including the fiber 22c is illustrated. In this embodiment, as shown in FIG. 6, the body portion 22a of the bladder 22 is composed of three rubber sheets 23, 24, and 25. The outer rubber sheet 23 and the inner rubber sheet 25 are each composed of a single rubber sheet. As the intermediate rubber sheet 24, at a portion that abuts against the inner surface of the sidewall portion 54, a rubber sheet 24a containing the above-described fiber 22c is used. Also, as the intermediate rubber sheet 24, at portions other than the portion that abuts against the inner surface of the sidewall portion 54, a rubber sheet 24b that does not contain the fiber 22c is used.

[0027] As shown in FIG. 2, the fiber 22c is included in a portion of the body portion 22a that abuts against the inner surface of the end portion 54c on the bead portion 52 side of the sidewall portion 54. Here, the end portion 54c on the bead portion 52 side is near the tip of the apex 52b that extends in the outer diameter direction from the annular bead core 52a.

[0028] In the above-described embodiment, the bladder 22 includes fibers 22c at a portion of the body portion 22a that abuts against the inner surfaces of the pair of side wall portions 54. When the local cover 50 is vulcanized using such a bladder 22, the portion containing the fibers 22c has high elastic strength, so that the local cover 50 is strongly pressed against the mold 30 at that portion. As a result, for example, a portion where the thickness of the local cover 50 is increased, such as the joint 54b of the side wall portion 54, can be strongly crushed. Thereby, the step (joint 54b) generated in the portion where the sheet-like rubber material is overlapped at the side wall portion 54 of the local cover 50 can be eliminated more neatly. For this reason, the appearance quality of the side wall of the tire can be improved.

[0029] Also, in the above-described embodiment, the fibers 22c are included inside the body portion 22a of the bladder 22. Thereby, the portion containing the fibers 22c has a high thermal conductivity. That is, temperature unevenness is less likely to occur in the portion containing the fibers 22c. As a result, the portion pressed by the portion of the bladder 22 containing the fibers 22c can improve the appearance quality of the tire.

[0030] In the above-described embodiment, the fibers 22c are continuously included in the circumferential direction at a portion of the body portion 22a that abuts against the inner surfaces of the pair of side wall portions 54. Therefore, the local cover 50 can be more strongly pressed against the mold 30 over the entire circumference of the portion of the body portion 22a that abuts against the inner surfaces of the side wall portions 54. That is, alignment between the joint 54b of the local cover 50 and the portion of the bladder 22 containing the fibers 22c is not required.

[0031] In the above-described embodiment, the fiber 22c is included in a portion of the body portion 22a that contacts the inner surface of the end portion 54c on the bead portion 52 side of the side wall portion 54. By the way, the rubber member constituting the local cover 50 is wound around the bead core 52a and the apex 52b. Therefore, the thickness has started to increase from the end portion 54c on the bead portion 52 side of the side wall portion 54. In the knowledge of the present inventor, the end portion 54c is difficult to be pressed against the mold 30, and air is likely to accumulate during vulcanization. If air accumulates between the mold 30 and the local cover 50 during vulcanization, there is a concern that a bare area may occur on the vulcanized tire. By including the fiber 22c in the portion where the bladder 22 contacts the end portion 54c, it becomes difficult for air to accumulate between the mold 30 and the vicinity of the end portion 54c. Thereby, the occurrence of bare areas can be reduced. The fiber 22c is preferably, for example, within a width of about 100 mm to 150 mm.

[0032] In addition, in this embodiment, the fiber 22c is not included in the portion of the body portion 22a that contacts the inner surface of the tread portion 56. That is, the portion that is strongly pressed against the mold 30 is limited to the side wall portion 54. Thereby, it becomes easier to uniformly pressurize the tread portion 56.

[0033] As described above, in the body portion 22a, the fiber 22c was included in the portion that contacts the inner surface of the side wall portion. However, the range in which the fiber 22c is included is not limited to such a form unless otherwise specified. The fiber 22c may be intermittently included in the circumferential direction or may be partially included. For example, in the body portion 22a, the fiber 22c may be included only in the portion where the joint 54b of the side wall portion 54 is formed.

[0034] Further, at least a part of the portion of the body portion 22a that contacts the inner surface of the tread portion 56 may also contain the fiber 22c. Further, the fiber 22c contained in at least a part of the portion that contacts the inner surface of the tread portion 56 and the fiber 22c contained in at least a part of the portion that contacts the inner surfaces of the pair of sidewall portions 54 may be independent. In this way, by selectively providing the portion containing the fiber 22c, the desired position in the local cover 50 can be strongly pressed against the mold 30. Thereby, the appearance quality of the tire can be further improved.

[0035] As described above, the bladder for vulcanization molding disclosed herein has been variously described. However, the bladder for vulcanization molding disclosed herein is not limited to the above-described embodiments and modifications unless otherwise specified. Further, the respective configurations of the variously described embodiments and modifications can be appropriately combined as long as they do not inhibit each other. This specification includes the following disclosure, and the following disclosure is not limited to the above-described embodiments.

[0036] The present disclosure (1) is a bladder for vulcanization molding for molding the inner surface of a local cover having a pair of bead portions, a pair of sidewall portions extending from the bead portions, and a tread portion connecting the pair of sidewall portions, the bladder having a cylindrical body portion and ring-shaped flange portions provided at both ends of the body portion, respectively, and at least a part of the portion of the body portion that contacts the inner surfaces of the pair of sidewall portions containing fibers.

[0037] The present disclosure (2) is the bladder for vulcanization molding according to the present disclosure (1). In the present disclosure (2), the fiber is formed in a mesh shape by a plurality of first fibers extending parallel to a first direction and a plurality of second fibers extending parallel to a second direction different from the first direction.

[0038] The present disclosure (3) is a bladder for vulcanization molding described in the present disclosure (1) or the present disclosure (2). In the present disclosure (3), the fibers are continuously included in the circumferential direction at a portion of the body portion that abuts on the inner surface of the pair of side wall portions.

[0039] The present disclosure (4) is a bladder for vulcanization molding in any combination with any one of the present disclosures (1) to (3). In the present disclosure (4), the fibers are included in a portion of the body portion that abuts on the inner surface of the end portion on the bead portion side of the side wall portion.

[0040] The present disclosure (5) is a bladder for vulcanization molding in any combination with any one of the present disclosures (1) to (4). In the present disclosure (5), the fibers are not included in a portion of the body portion that abuts on the inner surface of the tread portion.

[0041] The present disclosure (6) is a bladder for vulcanization molding in any combination with any one of the present disclosures (1) to (4). In the present disclosure (6), at least a part of the portion of the body portion that abuts on the inner surface of the tread portion contains fibers.

[0042] The present disclosure (7) is the bladder for vulcanization molding described in the present disclosure (6). In the present disclosure (7), the fibers included in at least a part of the portion that abuts on the inner surface of the tread portion and the fibers included in at least a part of the portion that abuts on the inner surface of the pair of side wall portions are independent.

[0043] The present disclosure (8) is a bladder for vulcanization molding in any combination with any one of the present disclosures (1) to (7). In the present disclosure (8), the fibers include nylon fibers.

[0044] The present disclosure (9) is a method for manufacturing a tire, in which a local cover is vulcanized using a bladder for vulcanization molding in any combination with any one of the present disclosures (1) to (8).

Explanation of Signs

[0045] 10 Vulcanizing device 20 Bladder Central Mechanism 22 Bladder for Vulcanization Molding 22a Barrel Part 22b Flange Part 23, 24, 24a, 24b, 25 Rubber Sheet 22c Fiber 26 Center Post 27a, 27b Clamping Ring 27b1 Through-Hole 30 Mold 32 First Side Mold 34 Second Side Mold 36 Tread Mold 50 Locator Cover 50a Carcass 50b Inner Liner 50c Belt 52 Bead Part 52a Bead Core 52b Apex 54 Sidewall Part 54a Sidewall Rubber 54b Joint 54c End Part 56 Tread Part 56a Tread Rubber

Claims

1. A bladder for vulcanization molding for molding the inner surface of a local cover having a pair of bead portions, a pair of sidewall portions extending from the bead portions, and a tread portion connecting the pair of sidewall portions, a cylindrical body portion, and ring-shaped flange portions provided at both ends of the body portion, respectively, characterized in that, at least a part of the portion of the body portion that contacts the inner surface of the pair of sidewall portions contains fibers, the fibers are not contained in the portion of the body portion that contacts the inner surface of the tread portion, bladder for vulcanization molding.

2. A bladder for vulcanization molding for molding the inner surface of a local cover having a pair of bead portions, a pair of sidewall portions extending from the bead portions, and a tread portion connecting the pair of sidewall portions, a cylindrical body portion, and ring-shaped flange portions provided at both ends of the body portion, respectively, characterized in that, at least a part of the portion of the body portion that contacts the inner surface of the pair of sidewall portions and at least a part of the portion of the body portion that contacts the inner surface of the tread portion contain fibers, at least a part of the fibers contained in the portion of the body portion that contacts the inner surface of the tread portion and at least a part of the fibers contained in the portion of the body portion that contacts the inner surface of the pair of sidewall portions are independent of each other, bladder for vulcanization molding.

3. The bladder for vulcanization molding according to claim 1 or 2, wherein the fibers are formed in a mesh shape by a plurality of first fibers extending parallel to a first direction and a plurality of second fibers extending parallel to a second direction different from the first direction.

4. The bladder for vulcanization molding according to any one of claims 1 to 3, wherein at least a part of the fibers contained in at least a part of the portion of the body portion that contacts the inner surface of the pair of sidewall portions are continuously contained in the circumferential direction at the portion of the body portion that contacts the inner surface of the pair of sidewall portions.

5. The bladder for vulcanization molding according to any one of claims 1 to 4, wherein at least a part of the fibers contained in at least a part of the portion of the body portion that contacts the inner surface of the pair of sidewall portions are contained in the portion of the body portion that contacts the inner surface of the end portion of the sidewall portion on the bead portion side.

6. The bladder for vulcanization molding according to claim 1, wherein at least a part of the portion of the body portion that contacts the inner surface of the tread portion contains fibers.

7. The fibers included in at least a part of the portion that contacts the inner surface of the tread portion and the fibers included in at least a part of the portion that contacts the inner surface of the pair of sidewall portions are independent. The bladder for vulcanization molding according to claim 6.

8. The bladder for vulcanization molding according to any one of claims 1 to 7, wherein the fibers include nylon fibers.

9. A method for manufacturing a tire, comprising vulcanizing a local cover using the bladder for vulcanization molding according to any one of claims 1 to 8.

Images