JP6939306B2 - Tire vulcanization mold - Google Patents

Description

The present invention relates to a mold for vulcanizing a tire.

For example, Patent Document 1 below proposes a vulcanization die for a tire having an improved bead ring structure in order to reduce vulcanization defects on the bead heel surface of the bead portion of the tire. The bead ring is formed of two or more ring pieces, and has a slit forming groove on the dividing surface of the ring piece on one side. The slit forming groove is formed as an exhaust slit having a gap of 0.02 to 0.08 mm between the divided surface of the ring piece on one side and the divided surface of the ring piece on the other side. The exhaust slit is useful for discharging the air remaining between the bead portion and the heel molding surface of the bead ring during vulcanization molding of the tire.

Japanese Unexamined Patent Publication No. 2012-161939

However, gas, oil, etc. generated from the rubber member tend to be mixed and fixed in the exhaust slit during the vulcanization process. Therefore, the bead ring spends a great deal of effort to remove the gas and oil sticking from the exhaust slit at the time of cleaning.

The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a tire vulcanization die capable of reducing the labor for cleaning the bead ring.

The present invention is a tire vulcanization die including a bead ring having a bead forming surface for vulcanizing the bead portion of the tire, and the bead ring has a seam appearing on the bead forming surface in the circumferential direction. The seam includes a plurality of contact portions where the inner ring piece contacts the outer ring piece and air in which the inner ring piece is separated from the outer ring piece. Each of the separation portions includes a plurality of separation portions for punching, and each of the separation portions has a slit shape in which the length in the circumferential direction is larger than the width in the radial direction.

In the tire vulcanization die of the present invention, it is desirable that the length of each of the separated portions in the circumferential direction is larger than the length of each of the contact portions in the circumferential direction.

In the tire vulcanization mold of the present invention, it is desirable that the length of the separated portion in the circumferential direction is 5% or more of the circumferential length of the joint.

In the tire vulcanization die of the present invention, it is desirable that four to eight contact portions are provided.

In the tire vulcanization die of the present invention, it is desirable that the width of the separation portion is less than 0.1 mm.

The bead ring of the tire vulcanization die of the present invention includes an inner ring piece and an outer ring piece fitted so that a seam appears in the circumferential direction on the bead molding surface. The seam includes a plurality of contacting portions where the inner ring piece contacts the outer ring piece and a plurality of separating portions for air bleeding where the inner ring piece is separated from the outer ring piece. Each separation portion has a slit shape in which the length in the circumferential direction is larger than the width in the radial direction. Even if gas, oil, or the like generated from the rubber member adheres to each of such separation portions, these can be easily removed during bead ring cleaning, so that the labor for cleaning the bead ring can be reduced. ..

It is sectional drawing of the tire vulcanization die of one Embodiment of this invention. It is a perspective view of a bead ring. It is a side view of a bead ring. It is a partially enlarged view of the seam of the inner ring piece and the outer ring piece. As a comparative example, it is a partially enlarged view of the seam of the tire vulcanization die.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of the tire vulcanization die 1 of the present embodiment. As shown in FIG. 1, the tire vulcanization die 1 of the present embodiment includes a molding surface inside which the outer surface 2s of the unvulcanized raw tire 2 is molded. The raw tire 2 is heated in the tire vulcanization die 1 and is pressed from the inside toward the molding surface side of the tire vulcanization die 1 by the expanded bladder 3. As a result, the raw tire 2 is vulcanized and molded to obtain a pneumatic tire.

The raw tire 2 includes a tread portion 4, a sidewall portion 5 extending inward in the radial direction of the tire from both ends thereof, and a bead portion 6 arranged inside in the radial direction of the tire. The raw tire 2 can have a known structure such as a toroid-shaped carcass or a belt layer arranged on the outside of the carcass.

The tire vulcanization die 1 of the present embodiment includes a tread segment 7, a sidewall segment 8, and a bead ring 10.

In the tread segment 7, the outer surface of the tread portion 4 is vulcanized. The sidewall segment 8 is vulcanized on the outer surface of the sidewall portion 5. The tread segment 7 and the sidewall segment 8 include a general mold configuration for forming a pneumatic tire, and detailed description thereof is omitted here.

The bead ring 10 has a bead forming surface 10s for vulcanizing the bead portion 6. The bead forming surface 10s of the present embodiment is formed including, for example, the bead heel surface of the bead portion 6.

FIG. 2 shows a perspective view of the bead ring 10. FIG. 3 shows a side view of the bead ring 10 as viewed from the bead forming surface 10s side in the tire axial direction. As shown in FIGS. 2 and 3, the bead ring 10 includes an inner ring piece 11 and an outer ring piece 12. The outer ring piece 12 is detachably fitted to the outer side of the inner ring piece 11 in the radial direction of the tire. The inner ring piece 11 and the outer ring piece 12 extend in an annular shape. The inner ring piece 11 and the outer ring piece 12 are fitted so that the seam 13 appears on the bead forming surface 10s in the circumferential direction.

FIG. 4 shows a partially enlarged view of the joint 13 between the inner ring piece 11 and the outer ring piece 12. As shown in FIG. 4, the seam 13 includes a plurality of contact portions 14 in which the inner ring piece 11 contacts the outer ring piece 12, and a plurality of air bleeding portions 14 in which the inner ring piece 11 is separated from the outer ring piece 12. Includes the separating portion 15. The contact portion 14 and the separation portion 15 are provided alternately in the circumferential direction. At the time of vulcanization molding, the air between the bead molding surface 10s and the outer surface of the bead portion 6 is discharged to the outside of the mold through the separation portion 15 and the air discharge path (not shown) connected to the separation portion 15. In addition, in FIG. 3 and FIG. 4, the separation portion 15 is colored for easy understanding.

Each separating portion 15 has a slit shape in which the length L1 in the circumferential direction is larger than the width d1 in the radial direction. Even if gas, oil, or the like generated from the rubber member is fixed to each of the separating portions 15, they can be easily removed at the time of cleaning the bead ring, so that the labor for cleaning the bead ring 10 can be reduced. In particular, when the inner ring piece 11 and the outer ring piece 12 are disassembled, the separating portion 15 is largely exposed in the circumferential direction, so that the bead ring 10 can be further easily cleaned. Further, the separating portion 15 has a small width in the circumferential direction and is less likely to be clogged with dirt due to the gas or oil as compared with the conventional one provided in a large number in the circumferential direction, and has high air bleeding performance for a long period of time. The bead ring 10 having the separating portion 15 of the present invention can be exhibited, and the cost required for processing the separating portion 15 can be suppressed as compared with the conventional one.

The separating portion 15 of the present embodiment extends, for example, with a constant width along the circumferential direction of the bead ring 10. Therefore, the separating portion 15 of the present embodiment has an arc shape that is smoothly curved along the circumferential direction. However, the separating portion 15 is not limited to such an aspect.

As shown in FIG. 3, it is desirable that the length L1 of the separating portion 15 in the circumferential direction is, for example, at least 5% or more of the circumferential length of the seam. Since such a separating portion 15 has a sufficiently long circumferential length, it is unlikely to be clogged even if gas or oil adheres to it, exhibits an air bleeding effect for a long period of time, and frequently cleans the bead ring 10. Can be reduced.

If the length L1 of the separating portion 15 is excessively large, the inner ring piece 11 and the outer ring piece 12 may be misaligned, and the uniformity of the formed tire may be deteriorated. In order to obtain the above-mentioned effect while suppressing the misalignment between the inner ring piece 11 and the outer ring piece 12, the length L1 in the circumferential direction of the separation portion 15 is preferably the circumferential length of the seam 13. It is 10% or more, more preferably 15% or more, preferably 30% or less, and more preferably 25% or less.

From the same viewpoint, it is desirable that the length L1 in the circumferential direction of each separation portion 15 is larger than the length L2 in the circumferential direction of each contact portion 14. Further, it is desirable that the L1s of the separating portions 15 are equal to each other. As a result, the air bleeding effect can be obtained evenly over the circumferential direction, and the uniformity of the formed tire can be improved.

As shown in FIG. 4, the width d1 of the separating portion 15 is preferably less than 0.1 mm, for example. Such a separating portion 15 can exert an air bleeding effect while suppressing the generation of burrs on the outer surface of the bead portion 6.

More specifically, the width d1 of the separating portion 15 is more preferably 0.08 mm or less, more preferably 0.06 mm or less, preferably 0.02 mm or more, and more preferably 0.04 mm or more. Such a separating portion 15 can exhibit a high air bleeding effect while suppressing the occurrence of the burr.

As shown in FIG. 3, the contact portion 14 of the present embodiment is configured such that a protrusion 16 provided on the inner ring piece 11 and projecting outward in the radial direction of the tire is in contact with the outer ring piece 12. In another aspect, for example, a protrusion provided on the outer ring piece 12 that protrudes inward in the radial direction of the tire may come into contact with the inner ring piece 11.

It is desirable that the contact portions 14 are provided at equal intervals in the circumferential direction, for example. As a result, the inner ring piece 11 and the outer ring piece 12 can be accurately fitted. Further, it is desirable that the contact portions 14 are provided, for example, at least three, more preferably four to eight. Such a contact portion 14 can surely align the inner ring piece 11 and the outer ring piece 12 while obtaining the above-mentioned air bleeding effect, and can suppress the misalignment between the two.

From the same viewpoint, the circumferential length L2 of the contact portion 14 is preferably 30 mm or more, more preferably 50 mm or more, preferably 100 mm or less, and more preferably 80 mm or less.

Although the tire vulcanization die of one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-mentioned specific embodiment as long as it does not deviate from the gist of the invention. It can be carried out by changing to the aspect of.

As an example, as shown in FIG. 4, a tire vulcanization die provided with a bead ring having a slit-like separating portion was prepared based on the specifications in Table 1. As a comparative example, as shown in FIG. 5, with respect to the joint a between the inner ring piece A and the outer ring piece B of the bead ring, the separation portion b whose circumferential length is smaller than the radial width is a circle. A large number of tire vulcanization molds provided in the circumferential direction were prepared. A certain number of tires were vulcanized and molded using each tire vulcanization die, and the appearance defect rate of the bead portion and the maintainability of the bead ring were tested.

<Performance defect rate of bead part>
300 tires of size 235 / 45R19 were vulcanized and molded, and the incidence of poor appearance of the bead portion generated by residual air between the bead portion and the heel molded surface of the bead ring was measured.

<Maintenance of bead ring>
After the above vulcanization molding, each bead ring was cleaned, and the time required to completely remove the dirt adhering to the bead ring was measured. The result is an index with a comparative example of 100, and the smaller the value, the better the maintainability of the bead ring.
The test results are shown in Table 1.

As a result of the test, it was confirmed that in the tire vulcanization die of the comparative example, the separated portion was easily clogged with dirt, and the appearance defect rate of the bead portion was slightly high. On the other hand, it was confirmed that the tire vulcanization die of the example had a lower appearance defect rate of the bead portion than the comparative example, and the frequency of bead ring cleaning could be reduced. Further, it was confirmed that the tire vulcanization die of the example was able to clean the dirt adhering to the separated portion in a short time and was excellent in the maintainability of the bead ring.

6 Bead part 10 Bead ring 10s Bead forming surface 11 Inner ring piece 12 Outer ring piece 13 Seam 14 Contact part 15 Separation part

Claims (5)

A tire vulcanization die including a bead ring having a bead molding surface for vulcanizing the bead portion of a tire.
The bead ring includes an inner ring piece and an outer ring piece fitted so that a seam appears in the circumferential direction on the bead forming surface.
The seam includes a plurality of contact portions in which the inner ring piece contacts the outer ring piece, and a plurality of separating portions for air bleeding in which the inner ring piece is separated from the outer ring piece.
Each separation portion has a length in the circumferential direction Ri slit-shaped der greater than the width in the radial direction,
The length of the separated portion in the circumferential direction is 5% or more of the circumferential length of the seam.
Tire vulcanization mold. A tire vulcanization die including a bead ring having a bead molding surface for vulcanizing the bead portion of a tire.
The bead ring includes an inner ring piece and an outer ring piece fitted so that a seam appears in the circumferential direction on the bead forming surface.
The seam includes a plurality of contact portions in which the inner ring piece contacts the outer ring piece, and a plurality of separating portions for air bleeding in which the inner ring piece is separated from the outer ring piece.
Each of the separation portions has a slit shape in which the length in the circumferential direction is larger than the width in the radial direction.
The contact portion is provided with 4 to 8 parts.
Tire vulcanization mold. The tire vulcanization die according to claim 1 or 2, wherein the length of each of the separated portions in the circumferential direction is larger than the length of each of the contact portions in the circumferential direction. The tire vulcanization die according to any one of claims 1 to 3, wherein the length of each contact portion in the circumferential direction is 30 mm or more. The tire vulcanization die according to any one of claims 1 to 4, wherein the width of the separation portion is less than 0.1 mm.

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