JP2021091150A - Tire vulcanization die and tire production method - Google Patents

Abstract

To make uniform the amount of vulcanization of a tire and shorten the time for vulcanization.SOLUTION: A tire vulcanization die comprises a die body 3 that heats the outside of a tire T by heat from a heat source 2. The die body 3 includes a heat inducer 4 for inducing the heat from the heat source 2 to a desired site P of the tire T. The heat inducer 4 has a thermal conductivity larger than that of the die body 3 and extends toward the desired site P from the heat source 2 side.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire vulcanization die and a tire manufacturing method that can contribute to uniform vulcanization amount and shortening of vulcanization time in each part of the tire.

The tire vulcanization mold includes upper and lower side molds for forming the side portions of the tire and tread molds for forming the tread portion of the tire. The upper and lower side molds are heated by the upper and lower platen plates that support the side molds. Further, the tread mold is heated by an actuator ring that expands and contracts the diameter of the tread mold.

On the other hand, the thickness of the tire differs depending on each part such as the tread part and the sidewall part. Therefore, there is a problem that a large amount of heating time is required in a portion having a large thickness as a vulcanization rate-determining portion, for example, a shoulder portion of a tread portion, and the vulcanization time of the tire as a whole becomes long. On the contrary, in the part other than the vulcanization rate-determining part, particularly in the sidewall part having a small thickness, overvulcanization occurs, which causes non-uniformity of the vulcanization degree.

Patent Document 1 below describes that a hollow annular recess is provided on the side surface of the mold corresponding to the sidewall portion to suppress the transfer of heat from the heat source to the sidewall portion.

Japanese Unexamined Patent Publication No. 58-49232

In Patent Document 1, since the transfer of heat amount is suppressed by the annular recess, over-vulcanization can be suppressed in the sidewall portion having a small thickness, and it can contribute to the uniform vulcanization degree. However, it is difficult to increase the supply of heat to the vulcanization rate-determining part, and it cannot contribute to shortening the vulcanization time.

An object of the present invention is to provide a tire vulcanization die and a tire manufacturing method that can contribute to uniform vulcanization amount of tire and shortening of vulcanization time.

The present invention is a tire vulcanization die including a mold body that heats the tire outside by heat from a heat source.
The mold body contains a heat derivative embedded in the mold body and for directing heat from the heat source to a desired portion of the tire.
The thermal derivative has a higher thermal conductivity than the mold body, and extends from the side of the heat source toward the side of the desired portion.

In the tire vulcanization die according to the present invention, the heat source preferably includes a first heat source and a second heat source.

In the tire vulcanization mold according to the present invention, the mold body includes a tread mold for molding a tread portion of the tire.
The thermal derivative is preferably embedded in the tread mold and includes a first thermal derivative that extends from the side of the first heat source to the side of the shoulder portion of the tread portion, which is the desired portion.

In the tire vulcanization die according to the present invention, the tread mold includes a segment for forming the tread portion and a sector shoe for holding the segment from the outside in the radial direction of the tire.
The first thermal derivative is preferably embedded in the sector shu.

In the tire vulcanization mold according to the present invention, the mold main body includes a side mold for molding a sidewall portion of the tire.
The thermal derivative is preferably embedded in the side mold and includes a second thermal derivative that extends from the side of the second heat source to the side of the sidewall portion that is the desired portion in the radial direction of the tire.

In the tire vulcanization die according to the present invention, it is preferable that a plurality of the thermal derivatives are embedded at intervals in the tire circumferential direction.

In the tire vulcanization die according to the present invention, the heat derivative is preferably a heat pipe.

The present invention is a tire manufacturing method, and includes a vulcanization step using the tire vulcanization die.

The present invention includes a thermal derivative embedded in the mold body as described above. The heat derivative can extend from the side of the heat source toward the desired portion of the tire and direct the heat from the heat source to the desired portion.

Therefore, when the desired portion is the vulcanization rate-determining portion, a large amount of heat can be applied to the vulcanization rate-determining portion in a short time. As a result, the temperature rise of the vulcanization rate-determining portion can be accelerated, and the vulcanization time of the tire can be shortened.

Further, since the vulcanization time of the tire can be shortened, the heating time for the portion other than the vulcanization rate-determining portion, particularly the sidewall portion having a small thickness, is also shortened. Therefore, supervulcanization is suppressed and the degree of vulcanization can be made uniform.

It is a partial cross-sectional view which shows one Example of the tire vulcanization die of this invention. It is a partial cross-sectional view which shows the main part together with a thermal derivative. It is a partial cross-sectional view which shows an example of the effect by a thermal derivative. It is sectional drawing explaining the heat pipe. FIG. 5 is a partial cross-sectional view showing another example of the effect of a thermal derivative.

Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, the tire vulcanization mold 1 of the present embodiment includes a mold body 3 that heats the tire T to the outside by heat from a heat source 2. Further, the mold body 3 is held by a container 7 having a heat source 2. In this example, the case where the heat source 2 includes the first heat source 2A and the second heat source 2B is shown.

The mold body 3 includes a tread mold 10 for molding the tread portion Ta of the tire T, upper and lower side molds 11U and 11L for molding the sidewall portion Tb of the tire T, and a bead portion Tc of the tire T. Includes upper and lower bead rings 12U, 12L for molding. Then, in the mold closed state Y in which the tread mold 10 and the side molds 11U and 11L are butted against each other, in this example, the tire T is vulcanized in a sideways state (a state in which the tire axis i faces vertically). It is molded.

The tread mold 10 includes a plurality of segments 14 divided in the tire circumferential direction, and a plurality of sector shus 15 that hold each segment 14 from the outside in the tire radial direction. A tread forming surface Sa for forming the tread portion Ta is arranged on the inner peripheral surface of the segment 14.

The segment 14 is interchangeably attached to the sector shoe 15. The tread mold 10 expands and contracts in diameter as the segment 14 and the sector shoe 15 move integrally in and out of the tire radial direction.

The upper and lower side molds 11U and 11L have side molding surfaces Sb for molding the sidewall portion Tb of the tire T.

The container 7 includes an upper platen plate 16, a lower platen plate 17, and an actuator ring 18.

The upper side mold 11U is fixed to the lower surface of the upper platen plate 16. The upper platen plate 16 can be attached to, for example, an elevating table (not shown) of a mold device and can move up and down together with the upper side mold 11U. Further, on the upper platen plate 16, each sector shoe 15 is held in a suspended state so as to be movable in and out in the radial direction of the tire via a guide means (not shown).

The lower side mold 11L is fixed to the upper surface of the lower platen plate 17. The lower platen plate 17 is supported, for example, on a table base (not shown) of a mold device.

The actuator ring 18 is supported so as to be vertically movable relative to the tread mold 10 via another elevator (not shown). A cone surface 18S is arranged on the inner peripheral surface of the actuator ring 18. By moving the actuator ring 18 downward, the cone surface 18S slides with the inclined surface 15S of each sector shoe 15, and pushes each sector shoe 15 inward in the tire radial direction until the mold closed state Y.

The actuator ring 18 incorporates a first heat source 2A. A second heat source 2B is built in each of the upper and lower platen plates 16 and 17, respectively.

As the first heat source 2A and the second heat source 2B, in this example, a jacket that is heated by supplying a high-temperature heat fluid such as steam is adopted. Heat fluid from a heat fluid supply means (not shown) such as a boiler is circulated and supplied to each jacket. In this example, separate heat fluid supply means are connected to the first heat source 2A and the second heat source 2B, and the temperature tb of the second heat source 2B is lower than the temperature ta of the first heat source 2A. Indicates when it is set to. The temperature tb of the second heat source 2B is about 150 ° C., and the temperature ta of the first heat source 2A is about 180 ° C.

As a result, the heat from the first heat source 2A incorporated in the actuator ring 18 is mainly transferred to the tread forming surface Sa through the sector shoe 15 and the segment 14. Similarly, the heat from the second heat source 2B incorporated in the upper platen plate 16 is mainly transferred to the side forming surface Sb through the upper side mold 11U, and is incorporated in the lower platen plate 17. The heat from the heat source 2B of 2 is mainly transferred to the side forming surface Sb through the lower side mold 11L.

In the tire vulcanization mold 1 of the present embodiment, the mold main body 3 includes a thermal derivative 4 embedded inside the mold main body 3. The thermal derivative 4 has a higher thermal conductivity than the mold body 3, and extends from the side of the heat source 2 toward the desired portion P of the tire T. Thereby, the heat from the heat source 2 can be induced to the desired portion P.

Therefore, when the desired portion P is the vulcanization rate-determining section, the supply of heat to the vulcanization rate-determining section is relatively increased, and the temperature rise of the vulcanization rate-determining section is accelerated. As a result, the vulcanization time of the tire can be shortened. Further, since the vulcanization time of the tire T can be shortened, the heating time for parts other than the vulcanization rate-determining portion, particularly the sidewall portion Tb having a small thickness, is also shortened, and over-vulcanization is suppressed to perform vulcanization. The degree can be made uniform.

In this example, the thermal derivative 4 includes a first thermal derivative 4A embedded inside the tread mold 10 and a second thermal derivative 4B embedded inside the upper and lower side molds 11U and 11L.

As shown in FIG. 2 as a representative of the lower portion of the tire vulcanization die 1, the first heat derivative 4A is a shoulder of the tread portion Ta which is a desired portion P1 from the side of the first heat source 2A. Extends to the side of the portion Ta1. In this example, this desired portion P1 is a vulcanization rate-determining portion and is a portion where vulcanization is the slowest.

The second heat derivative 4B extends from the side of the second heat source 2B to the side of the tire radial central portion Tb1 of the sidewall portion Tb which is the desired portion P2. In this example, the desired site P2 is a site where the rubber thickness is thin and supervulcanization is most likely to occur.

The thermal conductivity of the first thermal derivative 4A is larger than the thermal conductivity of the mold body 3 in which the first thermal derivative 4A is embedded. Specifically, when the first thermal derivative 4A is embedded inside the sector shu 15 as in this example, the thermal conductivity of the first thermal derivative 4A is the thermal conductivity of the sector shu 15. It is composed of larger members. When the first thermal derivative 4A is embedded inside the segment 14, the first thermal derivative 4A is composed of members having a thermal conductivity higher than that of the segment 14.

Further, the thermal conductivity of the second thermal derivative 4B is larger than the thermal conductivity of the mold body 3 in which the second thermal derivative 4B is embedded. Specifically, the second thermal derivative 4B is composed of members having a thermal conductivity larger than that of the upper and lower side molds 11U and 11L in which the second thermal derivative 4B is embedded.

Here, the segment 14 is formed of the same aluminum-based material (aluminum, aluminum alloy, etc.) as before in consideration of the workability of the tread molding surface Sa. On the other hand, the sector shoe 15, side molds 11U, 11L, and bead rings 12U, 12L are formed of the same iron-based material (iron, steel, etc.) as before in consideration of strength and cost. The thermal conductivity of the aluminum-based material is about 100 to 200 (W / m · K), and the thermal conductivity of the iron-based material is about 50 to 60 (W / m · K).

Examples of metal members having higher thermal conductivity than aluminum-based materials include gold, silver, and copper, and examples of composite members include heat pipes. In particular, the heat pipe 30 has a high thermal conductivity, so that it can be more preferably adopted. As conceptually shown in FIG. 4, the heat pipe 30 includes a pipe 31 made of a metal (for example, copper) having a high thermal conductivity, a working liquid (for example, water) 32 vacuum-sealed in the pipe 31, and a pipe. It has a well-known structure including a capillary structure (wick) 33 formed on the inner wall of 31, and when a temperature difference is given to both ends, the hydraulic fluid 32 circulates in the heat pipe 30 and moves from the high temperature part to the low temperature part. Transfer heat.

As shown in FIG. 3, when the second heat source 2B has a lower temperature than the first heat source 2A, the first and second heat derivatives 4A and 4B function as follows.

The first heat derivative 4A guides the heat from the first heat source 2A from the side of the first heat source 2A to the side of the shoulder portion Ta1 which is the vulcanization rate-determining portion (desired portion P1). As a result, a large amount of heat can be applied to the shoulder portion Ta1 in a shorter time. As a result, the temperature rise of the shoulder portion Ta1 can be accelerated, and the vulcanization time of the tire can be shortened.

In the tire vulcanization die 1, when the die is closed, for example, the upper and lower side molds 11U and 11L and the tread mold 10 are in contact with each other and are thermally conductive. Therefore, normally, the heat from the first heat source 2A also wraps around the upper and lower side molds 11U and 11L. As a result, during vulcanization, the temperature of the desired portion P2 rises to a temperature higher than the temperature tb of the second heat source 2B due to the heat from the first heat source 2A. As a result, the effect of suppressing supervulcanization on the desired site P2 is only the effect of shortening the vulcanization time described above.

However, in this example, the second heat derivative 4B extends from the side of the second heat source 2B toward the desired portion P2. The second heat derivative 4B can release the heat on the side of the desired portion P2 on the high temperature side to the side of the second heat source 2B on the low temperature side. That is, the temperature of the desired site P2 can be suppressed low, and the overvulcanization of the desired site P2 can be further suppressed.

The first and second thermal derivatives 4A and 4B can be formed in various shapes such as a disk shape, a rod shape, and a plate shape. However, it is preferable that the first and second thermal derivatives 4A and 4B are each composed of a plurality of rod-shaped bodies and are embedded at intervals in the tire circumferential direction. As a result, the strength of the mold body 3 in which the first and second thermal derivatives 4A and 4B are embedded can be ensured, and heat can be uniformly guided in the tire circumferential direction.

Further, it is preferable that the first thermal derivative 4A is provided in the sector shoe 15 rather than the segment 14. The reason is that by arranging the first heat derivative 4A closer to the first heat source 2A, a higher inducing effect can be obtained.

The first thermal derivative 4A can be provided separately in the segment 14 and the sector shu 15, and the first thermal derivative 4A is set to have a long length so as to penetrate both the segment 14 and the sector shu 15. It can also be provided.

Next, FIG. 5 illustrates a case where the tire T is a run-flat tire and, for example, a side reinforcing rubber layer Ts having a crescent-shaped cross section is arranged on the central portion Tb1 of the sidewall portion Tb. In this case, both the shoulder portion Ta1 which is the desired portion P1 and the central portion Tb1 which is the desired portion P2 each constitute a vulcanization rate-determining portion. In this case, it is preferable to set the temperature tb of the second heat source 2B to a temperature (about 180 ° C.) equal to the temperature ta of the first heat source 2A.

In this case, the first heat derivative 4A guides the heat from the first heat source 2A to the side of the shoulder portion Ta1 and accelerates the temperature rise of the shoulder portion Ta1. Similarly, the second heat derivative 4B induces the heat from the second heat source 2B to the side of the central portion Tb1, accelerates the temperature rise of the central portion Tb1, and shortens the vulcanization time of the tire.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments. The tire T is formed by a tire manufacturing method having a vulcanization step using the tire vulcanization die 1.

A tire vulcanization die having the structure shown in FIG. 1 was prototyped based on the specifications in Table 1. Then, the vulcanization time and the vulcanization amount ratio when vulcanizing the pneumatic tire (195 / 65R15) using the prototype tire vulcanization mold were evaluated. Each tire vulcanization die has substantially the same specifications except for the presence or absence of a thermal derivative. The common specifications and test methods are as follows.
<Common specifications>
Sector Shu --- Material (Iron: SS400, Thermal conductivity: 50-60W / m ・ K)
Segment --- Material (Aluminum: A5052, Thermal conductivity: 100-200W / m ・ K)
Side mold --- Material (iron: SS400, thermal conductivity: 50-60W / m ・ K))

(1) Vulcanization time:
Simulation of the time required for the vulcanization amount of each part of the tire to reach the required vulcanization amount based on the computer simulation (heat transfer calculation method between the mold and the raw tire) described in Japanese Patent Application Laid-Open No. 2018-122527. ) Was calculated. Evaluation was made using an index with the vulcanization time of Comparative Example 1 as 100. The smaller the value, the shorter the vulcanization time and the better the productivity.

(2) Vulcanization amount ratio:
The vulcanization amount Q1 in the shoulder portion of the tread portion and the vulcanization amount Q2 in the central portion (the portion including the maximum tire width position) of the sidewall portion are calculated from the calculation results of the above computer simulation, and the ratio Q2 / Compared in Q1. The closer the vulcanization amount ratio (Q2 / Q1) is to 1, the better the uniformity of vulcanization.

As shown in the table, it can be confirmed that the example product can make the vulcanization amount of the tire uniform and shorten the vulcanization time.

1 Tire sulfide mold 2 Heat source 2A 1st heat source 2B 2nd heat source 3 Mold body 4 Heat derivative 4A 1st heat derivative 4B 2nd heat derivative 10 Tread mold 11U, 11L Side mold 14 Segment 15 Sector Shu 30 Heat pipe P, P1, P2 Desired part T Tire Ta Tread part Ta1 Shoulder part Tb Side wall part Tb1 Central part

Claims (8)

A tire vulcanization mold that includes a mold body that heats the tire outside with heat from a heat source.
The mold body contains a heat derivative embedded in the mold body and for directing heat from the heat source to a desired portion of the tire.
A tire vulcanization mold having a higher thermal conductivity than the mold body and extending from the side of the heat source toward the side of the desired portion. The tire vulcanization die according to claim 1, wherein the heat source includes a first heat source and a second heat source. The mold body includes a tread mold for molding the tread portion of the tire.
The tire addition according to claim 2, wherein the heat derivative is embedded in the tread mold and includes a first heat derivative extending from the side of the first heat source to the side of the shoulder portion of the tread portion which is the desired portion. Vulcanization mold. The tread mold includes a segment for forming the tread portion and a sector shoe for holding the segment from the outside in the radial direction of the tire.
The tire vulcanization die according to claim 3, wherein the first thermal derivative is embedded in the sector sulfur. The mold body includes a side mold for molding the sidewall portion of the tire.
2. The heat derivative is embedded in the side mold and includes a second heat derivative extending from the side of the second heat source to the side of the tire radial central portion of the sidewall portion which is the desired portion. The tire vulcanization die according to any one of 4 to 4. The tire vulcanization die according to any one of claims 1 to 5, wherein a plurality of the thermal derivatives are embedded at intervals in the tire circumferential direction. The tire vulcanization die according to any one of claims 1 to 6, wherein the heat derivative is a heat pipe. A tire manufacturing method comprising a vulcanization step using the tire vulcanization die according to any one of claims 1 to 7.

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