JP2014008688A - Production method of tire and preshaping apparatus of tire vulcanization bladder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a tire in which vulcanization failure generating on a tire inner surface can be reduced and a preshaping apparatus of a tire vulcanization bladder.SOLUTION: Before a green tire G is vulcanized, a tire vulcanization bladder 2 is disposed in a preshape mold 12, a pressure medium A supplied from a compressor 14 is injected through an inlet 13a formed at an injection pipe 13 into the tire vulcanization bladder 2 to be expanded, and is typed to an inner surface shape of the preshape mold 12, thereby an elongation ratio of a desired site of the tire vulcanization bladder 2 is changed, the typed tire vulcanization bladder 2 is disposed at the inside of the green tire G to be expanded by a vulcanization apparatus, to thereby be contacted to each site of an inner surface of the green tire G in a preset order, and the green tire G is performed by pressing force to a vulcanization mold by the expanded tire vulcanization bladder 2.

Description

  TECHNICAL FIELD The present invention relates to a tire manufacturing method and a tire vulcanizing bladder pre-shaping device, and more specifically, a tire manufacturing method and a tire vulcanizing bladder pre-shaping device capable of reducing vulcanization failures occurring on the inner surface of a tire. It is about.

  When the tire is vulcanized, the green tire is pressed against the mold by injecting a heat medium such as steam into a tire vulcanization bladder inserted into the green tire with the mold closed and inflating it. While heating, vulcanize. The tire vulcanization bladder is a rubber cylinder, and the upper and lower clamp portions thereof are each held by a clamp holding portion constituting a central mechanism (for example, see Patent Document 1).

  Usually, when the tire vulcanization bladder is inflated, the center portion is first brought into contact with the inner surface of the green tire, and then the bead portion and the shoulder portion are brought into contact in this order. Therefore, the air between the inner surface of the green tire and the outer surface of the tire vulcanizing bladder may remain between the two without being sufficiently discharged to the outside. Due to the remaining air, there is a problem that a vulcanization failure occurs on the inner surface of the vulcanized tire.

JP 2010-30067 A

  An object of the present invention is to provide a tire manufacturing method and a pre-shaping device for a tire vulcanization bladder that can reduce a vulcanization failure occurring on the inner surface of the tire.

  In order to achieve the above object, the tire manufacturing method of the present invention has a cylindrical tire vulcanization bladder placed in a pre-shape mold and inflated before vulcanizing a green tire, so that the inner surface of the pre-shape mold can be expanded. By pressing and molding, the expansion rate of the desired part of the tire vulcanization bladder is changed, and this molded tire vulcanization bladder is placed inside the green tire inside the closed vulcanization mold and inflated. The inflatable tire vulcanization bladder is brought into contact with each part of the inner surface of the green tire in a preset order, and the inflated tire vulcanization bladder is used to attach the green tire to the vulcanization mold. It is characterized by heating and vulcanizing while pressing.

  A pre-shaping device for a tire vulcanizing bladder according to the present invention includes a pre-shaped mold in which a cylindrical tire vulcanizing bladder is disposed inside before vulcanizing a green tire, and a tire disposed in the pre-shaped mold. An injection means for injecting a pressurized medium into the inside of the vulcanizing bladder, inflating the tire vulcanizing bladder by injecting the pressurized medium and pressing the inner surface of the pre-shaped mold to mold the tire The vulcanized bladder is characterized in that the stretch ratio of a desired portion is changed.

  According to the present invention, the tubular tire vulcanization bladder is placed in a pre-shaped mold and inflated and molded before the green tire is vulcanized, so that the elongation rate of a desired portion of the tire vulcanization bladder is increased. To change. As a result, when the molded tire vulcanization bladder is placed inside the green tire and inflated, the inflated tire vulcanization bladder is applied to each part of the inner surface of the green tire in a desired order set in advance. It becomes possible to contact. Therefore, if the expansion ratio of the desired part of the tire vulcanization bladder is changed according to the shape of the inner surface of the green tire, the air between the inner surface of the green tire and the outer surface of the expanding tire vulcanization bladder is smoothly transferred to the outside. It can be discharged. Along with this, it is possible to suppress the occurrence of vulcanization failure on the tire inner surface caused by the air remaining between the two.

  In the tire manufacturing method of the present invention, the tire vulcanization bladder can be molded only by a portion formed by the curved surface of the inner surface of the pre-shaped mold. As a result, the molded tire vulcanization bladder is advantageous in improving durability because a portion that tends to become a starting point of breakage when expanded is not formed.

  Further, the tire vulcanization bladder arranged in the pre-shaped mold can be inflated by injecting a pressurized medium of 0.1 MPa or more to be molded. When molding the tire vulcanization bladder, the tire vulcanization bladder may be heated to 50 ° C. or higher. By these methods, the tire vulcanization bladder can be molded in a shorter time.

  If the tire inner surface shape is a general tire, the tire vulcanization bladder that expands inside the closed vulcanization mold is arranged in the order from the center portion of the green tire toward the bead portion in a cross-sectional view of the green tire. It is good to make it contact | abut with respect to each site | part of the inner surface of a green tire. Thereby, the air between the inner surface of the green tire and the outer surface of the inflating tire vulcanizing bladder can be smoothly discharged to the outside, and air can be prevented from remaining between the two.

It is explanatory drawing which illustrates the whole outline | summary of the pre shaping apparatus of the tire vulcanization bladder of this invention in a longitudinal cross-section. It is explanatory drawing which illustrates the process which has shape | molded the tire vulcanization bladder in a longitudinal cross section. It is a longitudinal cross-sectional view which illustrates the type | molded tire vulcanization bladder. It is explanatory drawing which illustrates the vulcanization apparatus which installed the type | molded tire vulcanization bladder in a longitudinal cross-section. It is explanatory drawing which illustrates the process of vulcanizing a green tire using the vulcanizing apparatus of FIG. 4 in a longitudinal section. It is explanatory drawing which illustrates the state which the type | molded tire vulcanization bladder contact | abuts to the center part of the inner surface of a green tire in a longitudinal cross-section. It is explanatory drawing which illustrates the state which the tire vulcanization bladder of FIG. 6 contact | abuts to the shoulder part of the inner surface of a green tire in a longitudinal cross-section. It is explanatory drawing which illustrates the state which the tire vulcanization bladder of FIG. 7 contact | abuts to the bead part of the inner surface of a green tire in a longitudinal cross-section.

  Hereinafter, a tire manufacturing method and a tire shaping bladder pre-shaping device of the present invention will be described based on the embodiments shown in the drawings.

  A pre-shaping device 11 of the present invention illustrated in FIG. 1 is a device that molds a tubular tire vulcanizing bladder 2, and includes a pre-shaped mold 12 and a tire vulcanizing bladder disposed in the pre-shaped mold 12. 2 is provided with injection means for injecting the pressurized medium A. The pre-shaped mold 12 includes an upper mold 12a and a lower mold 12b, and each inner surface is formed in a desired shape. The injection means includes an injection pipe 13 that vertically penetrates the lower mold 12 b and a compressor 14 that supplies the pressurized medium A to the injection pipe 13. As the pressurized medium A, for example, air is used. In this embodiment, a heater is further provided as the heating means 15 for heating the pre-shaped mold 12.

  The tire vulcanization bladder 2 is formed, for example, by vulcanizing butyl rubber into a cylindrical shape, and the upper clamp portion 3a and the lower clamp portion 3b are respectively an upper clamp holding portion 5a attached to the injection tube 13. It is held by the lower clamp holding part 5b.

  As illustrated in FIG. 2, the tire vulcanizing bladder 2 is disposed inside a pre-shaped mold 2 that is closed by assembling an upper mold 12 a and a lower mold 12 b. In this state, the on-off valve 14 a is opened and the pressurized medium A supplied from the compressor 14 is injected into the tire vulcanization bladder 2 through the injection port 13 a formed in the injection pipe 13.

  The tire vulcanization bladder 2 is inflated by the injected pressurized medium A and pressed against the inner surface of the pre-shaped mold 12. Thereby, each site | part of the tire vulcanization bladder 2 is type | molded to the inner surface shape of the pressed pre-shape mold 12, and the expansion | extension rate of a desired site | part is changed. That is, the inner shape of the pre-shaped mold 12 is formed to change a desired portion of the tire vulcanization bladder 2 to a desired elongation rate.

  For example, as shown in FIG. 3, the tire vulcanization bladder 2 after molding changes the expansion rate of only the portion corresponding to the shoulder portion Ts on the inner surface of the green tire G. Here, the expansion rate is an elongation rate (area expansion rate) of the shape of the tire vulcanization bladder 2 after molding with respect to the original shape of the tire vulcanization bladder 2. For example, the elongation ratio of the portion corresponding to the shoulder portion Ts is set to a range of 10% or more, more preferably 50% or more and 100% or less. The greater the expansion rate is changed by molding, the more easily the portion expands when the tire vulcanization bladder 2 is expanded when the green tire G is vulcanized. The desired site for changing the stretch rate is not limited to the site corresponding to the shoulder portion Ts, but may be another site, or the stretch rate of a plurality of sites may be changed.

  The tire vulcanization bladder 2 demolded from the pre-shaped mold 12 slightly returns to its original shape. Therefore, the inner shape of the pre-shaped mold 12 is preferably formed in consideration of this restoration condition. For example, when the stretch rate of the desired part of the tire vulcanization bladder 2 is 50%, the stretch rate is 60% to 70% (+ 10%) in a state where the desired part is pressed against the inner surface of the pre-shaped mold 11. The inner shape of the pre-shaped mold 11 is formed so as to be (˜ + 20%).

  The inner surface of the pre-shaped mold 12 is preferably formed with a curved surface at all the portions that contact the inflated tire vulcanization bladder 2. With this specification, the molded tire vulcanization bladder 2 is advantageous in improving durability because it does not form a corner portion that tends to be a starting point of breakage when expanded.

  In order to inflate and mold the tire vulcanization bladder 2, for example, a pressurized medium A of 0.1 MPa or more is injected. As the injection pressure is higher, the tire vulcanization bladder 2 can be molded in a shorter time. However, even if the injection pressure is excessive, the time required for molding does not change so much, so it is set to about 0.1 MPa to 0.5 MPa.

  The temperature of the tire vulcanization bladder 2 at the time of molding is set in the range of 20 ° C to 200 ° C, for example. Since the time required for molding can be shortened at a high temperature, the tire vulcanizing bladder 2 is heated to 50 ° C. or higher, more preferably 70 ° C. or higher and 100 ° C. or lower using the heating means 15.

  In the tire manufacturing method of the present invention, a tire vulcanizing apparatus 1 illustrated in FIG. 4 is used. This vulcanizing device 1 includes a tire vulcanizing bladder 2 molded using a pre-shaping device 11, and disk-shaped upper clamp holding portions for holding an upper clamp portion 3a and a lower clamp portion 3b of the vulcanization bladder 2, respectively. 5a and a central mechanism 4 having a lower clamp holding portion 5b.

  The center post 4a of the center mechanism 4 has an inlet 6 for injecting a heat medium H such as steam into the tire vulcanizing bladder 2, and an outlet 7 for discharging the heat medium H to the outside of the tire vulcanizing bladder 2. Is provided. Control valves 8 a and 8 b for opening and closing the supply line for supplying the heat medium H to the inlet 6 and the discharge line for discharging the heat medium H from the discharge port 7 are installed. A vacuum pump is connected to the discharge line.

  When manufacturing a pneumatic tire, first, the green tire G is placed inside the vulcanization mold 9 installed in the vulcanizer 1. The vulcanization mold 9 is placed on the base plate 10b and is divided into a plurality of circumferential sectors 9a, an annular side plate 9b installed on the lifting plate 10a, and the base plate 10b. It is comprised by the cyclic | annular side plate 9c installed.

  After the tire vulcanization bladder 2 is placed inside the green tire G, the rear side of each sector 9a is moved by the guide plate protruding downward from the lift plate 10a by moving the lift plate 10a downward. Press the back segment attached to. Thereby, each sector 9a is slid toward the center post 4a, and the vulcanization mold 9 is closed.

  As illustrated in FIG. 5, with the vulcanization mold 9 closed, the tire vulcanization bladder 2 is green by injecting the heat medium H from the injection port 6 into the tire vulcanization bladder 2 that has been expanded to some extent. The tire G is inflated along the inner surface of the tire G. Then, the inner surface of the green tire G is pressed by the inflated tire vulcanizing bladder 2 and heated while pressing the green tire G against the mold 9. The green tire G is heated to a predetermined temperature while being pressed at a predetermined pressure and vulcanized, and then the lift plate 10a (side plate 9b) is moved upward to open the mold 9. Next, the vulcanized tire is moved upward and extracted from the tire vulcanization bladder 2 and taken out.

  When the tire vulcanization bladder 2 is inflated, the tire vulcanization bladder 2 that inflates with respect to the inner surface of the green tire G in the cross-sectional view of the green tire G as shown in FIG. Abut. However, in the present invention, since the tire vulcanization bladder 2 in which the expansion ratio of the desired portion (the portion corresponding to the shoulder portion Ts) is changed in advance is used, the inflating tire vulcanization bladder 2 is then illustrated in FIG. Then, it contacts the shoulder Ts, and then contacts the bead Tb as illustrated in FIG.

  In other words, the portion corresponding to the shoulder portion Ts of the tire vulcanizing bladder 2 has a higher expansion rate due to the molding, and therefore is more easily expanded than the portion corresponding to the bead portion Tb. Therefore, the inflating tire vulcanization bladder 2 contacts the shoulder Ts before the bead Tb. The portion corresponding to the center portion Tc of the tire vulcanizing bladder 2 is the portion that is most distant from the fixed ends (the upper clamp holding portion 5a and the lower clamp holding portion 5b) and easily expands. The bladder 2 first comes into contact with the center portion Tc.

  The inflating tire vulcanizing bladder 2 abuts against the respective portions of the inner surface of the green tire G in the order from the center portion Tc to the bead portion Tb. Therefore, the air between the inner surface of the green tire G and the outer surface of the expanding tire vulcanization bladder 2 is smoothly discharged to the outside. As a result, the occurrence of vulcanization failure (such as poor appearance) on the tire inner surface caused by the air remaining between the inner surface of the green tire G and the outer surface of the tire vulcanizing bladder 2 is suppressed. As a result, it contributes to improving the quality of the vulcanized tire.

  As described above, when the tire vulcanization bladder 2 is molded before the green tire G is vulcanized, and the expansion ratio of the desired portion of the tire vulcanization bladder 2 is changed, when the green tire G is vulcanized, The inflating tire vulcanization bladder 2 can be brought into contact with each part of the inner surface of the green tire G in a desired order set in advance. Therefore, in order to suppress the occurrence of vulcanization failure on the inner surface of the vulcanized tire, the stretch rate of the desired portion of the tire vulcanization bladder 2 may be changed according to the inner surface shape of the green tire G.

  General-purpose pneumatic tires for passenger cars (195 / 65R15) with the same specifications, but different from the tire vulcanization bladder only in seven ways (conventional examples, Examples 1 to 6), vulcanization of the sectional type Vulcanization was performed under the same conditions using a mold. In each case, the incidence of vulcanization failure occurring on the inner surface of the vulcanized tire was investigated, and the results were as shown in Table 1. Here, the vulcanization failure is a so-called light liner appearance defect caused by air remaining between the inner surface of the green tire and the outer surface of the tire vulcanization bladder.

  In Conventional Example 1, a cylindrical tire vulcanizing bladder was used without being molded. In Examples 1 to 6, the pre-shaping device was used to mold only the portion corresponding to the shoulder portion of the tire vulcanization bladder as in the shape illustrated in FIGS. 2 and 3. And the extension rate of this part was 35%-75% as shown in Table 1. When molding, the tire vulcanization bladder was inflated by injecting air at an appropriate pressure in the range of 0.1 MPa to 0.4 MPa, and this expanded state was maintained for an appropriate time in the range of 10 minutes to 60 minutes. .

  From the results of Table 1, it can be seen that in Examples 1 to 6 compared to the conventional example, the occurrence of vulcanization failure on the tire inner surface is suppressed by pre-molding the tire vulcanization bladder. This is because the tire vulcanization bladder expanded during vulcanization comes into contact with the inner surface of the green tire in the order of the center portion, the shoulder portion, and the bead portion in this order, and the inner surface of the green tire and the outer surface of the tire vulcanization bladder This is probably because the air in between was easily discharged to the outside, and the air did not easily remain between them.

DESCRIPTION OF SYMBOLS 1 Vulcanization apparatus 2 Tire vulcanization bladder 3a Upper clamp part 3b Lower clamp part 4 Center mechanism 4a Center post 5a Upper clamp holding part 5b Lower clamp holding part 6 Inlet 7 Outlet 8a, 8b Control valves 9, 9a, 9b, 9c Vulcanization mold 10a Elevating plate 10b Base plate 11 Pre-shaping device 12, 12a, 12b Pre-shaping mold 13 Injection pipe 13a Inlet 14 Compressor 14a On-off valve 15 Heating means G Green tire Tb Bead part Tc Center part Ts Shoulder part

Claims (8)

  Before vulcanizing the green tire, place the tubular tire vulcanization bladder in the pre-shape mold, inflate it, press against the inner surface of the pre-shape mold, and mold it to the desired part of the tire vulcanization bladder The expansion rate of the tire is changed, and the molded tire vulcanization bladder is placed inside the green tire inside the closed vulcanization mold and inflated, so that each part of the inner surface of the green tire is inflated. The tire vulcanizing bladder is brought into contact with the tire vulcanizing bladder in a preset order, and the inflated tire vulcanizing bladder is heated and vulcanized while pressing the green tire against the vulcanizing mold. Manufacturing method.   The tire manufacturing method according to claim 1, wherein the tire vulcanizing bladder is molded only by a portion formed by a curved surface of the inner surface of the pre-shaped mold.   The tire manufacturing method according to claim 1 or 2, wherein the tire is vulcanized and molded by injecting a pressurized medium of 0.1 MPa or more into a tire vulcanizing bladder disposed in the pre-shaped mold.   The method for manufacturing a tire according to any one of claims 1 to 3, wherein the tire vulcanization bladder is heated to 50 ° C or higher when the tire vulcanization bladder is molded.   The tire vulcanization bladder that expands inside the closed mold vulcanization mold, with respect to each part of the inner surface of the green tire in the order from the center portion of the green tire to the bead portion in a cross-sectional view of the green tire The manufacturing method of the tire in any one of Claims 1-4 made to contact.   A pre-shape mold in which a cylindrical tire vulcanization bladder before vulcanizing a green tire is disposed, and an injection for injecting a pressure medium into the tire vulcanization bladder disposed in the pre-shape mold Means for inflating the tire vulcanization bladder by injecting the pressurized medium and pressing the inner surface of the pre-shaped mold to mold the tire vulcanization bladder, thereby changing the expansion ratio of a desired portion of the tire vulcanization bladder. A pre-shaping device for a tire vulcanization bladder.   7. The pre-shaping device for a tire vulcanization bladder according to claim 6, wherein a portion of the inner surface of the pre-shaped mold that is in contact with the inflated tire vulcanization bladder is formed by a curved surface.   The pre-shaping device for a tire vulcanizing bladder according to claim 6 or 7, further comprising a heating means for heating the pre-shaped mold.

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