JP6172810B2 - Turn up bladder - Google Patents

Description

  The present invention relates to a turn-up bladder used for folding back an end portion of a carcass ply in forming a tire.

  Forming a pneumatic tire usually includes a step of folding back (turning up) an end portion of a carcass ply formed in a cylindrical shape. The carcass ply is bonded to the outer periphery of the forming drum to form a cylindrical shape, and an annular bead core and a bead filler disposed near the end of the carcass ply are sandwiched by the carcass ply whose end is folded back. A rubber back expansion mechanism called a turn-up bladder (or side bladder) is used for folding the end portion of the carcass ply.

  The usual turn-up bladder is in a contracted state, and when the end portion of the carcass ply is folded back, it is temporarily expanded by supply of air, but immediately after that, exhaust is performed to return to the contracted state. The turn-up bladder at the time of expansion is deformed so that its cross-section approaches a circle while expanding its outer diameter, but depending on the mode, the end of the carcass ply does not adhere to the bead core or bead filler, and air is interposed between them. By mixing, a process defect called “air entering” may occur.

  In the turn-up bladder described in Patent Document 1, a cord that is parallel to the circumferential direction (angle 0) in the vicinity of the fixed leg portion on the side close to the forming drum among the expanding portions of the cord ply that forms the skeleton thereof A ring-shaped reinforcing band in which is embedded is formed integrally. Such a structure is intended to prevent the operation of dragging the inner portion (the portion closer to the forming drum) with the diameter growth of the central portion, thereby suppressing the occurrence of air entry.

  However, in the molding of tires, the required turn-up amount (the length of the end portion of the folded carcass ply) varies depending on the flatness ratio, etc., and accordingly, the desirable form of expansion deformation of the turn-up bladder also varies. . For example, in tires with a low flatness ratio, the required turn-up amount is small, so it is advantageous to suppress the outer diameter of the turn-up bladder during inflation, and if the outer diameter becomes larger than necessary, the end of the carcass ply May not be folded back smoothly and may cause air entry. Further, in a portion where the load due to repeated expansion and contraction is large, there is a room for improving durability because a hole that causes puncture may be formed.

  Since the turn-up bladder described in the cited document 1 is formed integrally with a reinforcing band in a specific portion in the vicinity of the fixed leg portion on the side close to the forming drum, the turn-up bladder at the time of expansion as described above is used. It is not suitable for the purpose of reducing the outer diameter. Of course, the portion where the reinforcing band in which the cord is embedded as described above is hardly expanded in diameter, and therefore, it is considered to be practically difficult to apply to a portion away from the fixed leg portion. In addition, since the part away from the fixed leg portion is not reinforced, it cannot be said that it is sufficient for improving the durability.

JP 2004-202992 A

  This invention is made | formed in view of the said situation, The objective is to provide the turn-up bladder which can implement | achieve suppression of air entering and improvement of durability.

  The above object can be achieved by the present invention as described below. That is, the turn-up bladder according to the present invention is a turn-up bladder used for molding a tire, and a main body ply that forms a skeleton of the bladder from one end portion to the other end portion, and a narrower width than the main body ply. A reinforcement ply formed on the main body ply, the main body ply and the reinforcement ply each including a cord extending obliquely with respect to the circumferential direction, and the cord of the reinforcement ply with respect to the circumferential direction. The angle is in the range of 50 to 90 degrees and is equal to or smaller than the cord angle of the main body ply with respect to the circumferential direction.

  In this turn-up bladder, the cord angle of the reinforcing ply is in the range of 50 to 90 degrees and is the same as or smaller than the cord angle of the main ply. The diameter expansion can be suppressed to a degree corresponding to the cord angle. Therefore, if this is utilized, the expansion | swelling deformation | transformation of a turn-up bladder can be controlled and generation | occurrence | production of air can be suppressed so that the edge part of a carcass ply may contact | adhere to a bead core or a bead filler. In addition, the reinforcing ply can be bonded to a portion where the load due to repeated expansion and contraction is large, which contributes to improvement in durability.

  The cord angle of the reinforcing ply with respect to the circumferential direction is preferably in the range of 80 to 90 degrees. According to such a configuration, the diameter of the portion where the reinforcing ply is bonded is allowed to be increased accordingly, so that the application range of the reinforcing ply is widened, and in order to realize the expansion deformation of the turn-up bladder that can suppress the entry of air. convenient.

  The difference between the cord angle of the reinforcing ply and the cord angle of the main body ply is preferably within 10 degrees. As a result, the change in the cord angle between the main ply and the reinforcing ply becomes gradual, and it is possible to prevent the turn-up bladder from deforming into an irregular shape during expansion, which is convenient for suppressing the occurrence of air entry. .

  It is preferable that the cord of the reinforcing ply is inclined in the same direction as the cord of the main body ply. According to such a configuration, the diameter of the portion where the reinforcing ply is bonded is allowed to be increased accordingly, so that the application range of the reinforcing ply is widened, and in order to realize the expansion deformation of the turn-up bladder that can suppress the entry of air. convenient.

  It is preferable to include a reinforcing rubber tape that is formed narrower than the main body ply and is bonded to the main body ply. According to such a configuration, in addition to the reinforcing ply, the reinforcing rubber tape can also provide a reinforcing effect, and the durability can be improved more favorably.

Sectional drawing which shows roughly an example of the turn-up bladder concerning this invention Sectional view when the turn-up bladder of FIG. 1 is straightened Plan view showing the turn-up bladder of FIG. Schematic explaining the process of folding the end of the carcass ply

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The turn-up bladder 1 shown in FIGS. 1 and 2 (hereinafter sometimes simply referred to as “the bladder 1”) is used to fold the end portion of the carcass ply in the molding of a tire as described later. The bladder 1 includes a main body ply 2 that forms a skeleton of the bladder from one end portion 11 to the other end portion 12, and a reinforcing ply 3 that is formed narrower than the main body ply 2 and is bonded to the main body ply 2. With. The bladder 1 in FIG. 1 is in a contracted state, and is deformed into a toroidal shape by supplying air to the bladder 1 and expanding it.

  Since the end portions 11 and 12 of the bladder 1 are each provided with an annular bead 13 made of a converging body such as a steel wire, the end portions 11 and 12 do not expand in diameter even during expansion. The end of the main body ply 2 is folded back so as to sandwich the bead 13, and in this embodiment, the reinforcing ply 3 is bonded to the end of the folded end. As described above, the reinforcing ply 3 is narrower than the main body ply 2. This means that the width W3 of the reinforcing ply 3 is smaller than the width W2 of the main body ply 2 measured as shown in FIG. means. The width W3 is set to, for example, 5 to 90% of the width W2, and is set to 50 to 90% of the width W2 when the region to be bonded is wide.

  The inner liner 4 is formed of rubber having excellent air permeation resistance such as butyl rubber, and is bonded to the inner peripheral side of the main body ply 2 in order to maintain the internal pressure during expansion to form the inner peripheral surface of the bladder 1. ing. Further, one or more cover liners (not shown) can be bonded to the outer peripheral side of the main body ply 2 bonded with the reinforcing ply 3 so as to cover them. The cover liner is formed of, for example, a rubber sheet having a smaller thickness than the main body ply 2 and the reinforcing ply 3.

  As shown in FIG. 3, the main body ply 2 and the reinforcing ply 3 include cords C <b> 2 and C <b> 3 that extend while being inclined with respect to the circumferential direction (vertical direction in FIG. 3). In the main body ply 2, a plurality of cords C <b> 2 are aligned so as to be parallel to each other, and the cord C <b> 3 in the reinforcing ply 3 is the same as this. Although conceptually depicted in FIG. 3, in practice, the codes C2 and C3 are arranged more densely. Examples of the material of the cords C2 and C3 include organic fibers such as polyester, rayon, and nylon.

  The cord angle θ3 of the reinforcing ply 3 with respect to the circumferential direction is in the range of 50 to 90 degrees, and is the same as or smaller than the cord angle θ2 of the main body ply 2 with respect to the circumferential direction. That is, the relationship of 50 degrees ≦ θ3 ≦ 90 degrees is satisfied, and the relationship of θ3 ≦ θ2 is satisfied. Thereby, in the site | part which bonded the reinforcement ply 3, diameter expansion can be suppressed by the degree according to the cord angle (theta) 3, while accepting a certain amount of diameter expansion. Further, the reinforcement ply 3 is bonded to a portion where the load due to repeated expansion and contraction is large, which contributes to improvement in durability.

  The cord angle θ2 is set, for example, within a range of 60 to 90 degrees, but is preferably within a range of 80 to 90 degrees for smoothly expanding the bladder 1. The cord angle θ3 is preferably in the range of 65 to 90 degrees, and more preferably in the range of 80 to 90 degrees. When the cord angle θ3 is smaller than the cord angle θ2, it is preferable to set the cord angle θ3 to 88 degrees or less. In any case, the difference (θ2−θ3) between the cord angle θ3 and the cord angle θ2 is preferably within 10 degrees.

  FIG. 4 shows how a tire is molded using this bladder 1. First, as shown in (A), the inner liner 5 and the carcass ply 6 as tire constituent members are bonded to the outer periphery of the forming drum 7 in a state in which both end portions protrude outward, and are formed into a cylindrical shape. . Subsequently, as shown in (B), after the end portion of the molding drum 7 is narrowed and the end portion of the carcass ply 6 is deflated, the bead core 8a and the bead filler 8b are disposed in the vicinity thereof. At this time, the bladder 1 stands by in the vicinity of the inside of the place where the bead core 8 a is arranged, and specifically, is stored in the molding drum 7.

  Next, as shown in (C), the bladder 1 is supplied with air and expanded, and the end portion of the carcass ply 6 is folded back so as to sandwich the bead core 8a and the bead filler 8b. In the present embodiment, the bladder 1 is pressed against the molding drum 7 by a mechanism (not shown). The desirable expansion and deformation mode of the bladder 1 for preventing the entry of air varies depending on various conditions such as the flatness of the tire to be molded. For example, in a tire having a low flat rate (for example, a flat rate of around 30), it is advantageous to suppress the outer diameter of the bladder 1 during expansion, and in a tire having a high flat rate (for example, a flat rate of around 80), It is effective to appropriately increase the outer diameter of the bladder 1 during expansion.

  The expansion deformation of the bladder 1 changes in accordance with the portion where the reinforcing ply 3 is bonded, the cord angle θ3 thereof, and the like. Therefore, the expansion deformation of the bladder 1 can be controlled based on the reinforcing ply 3. Therefore, by utilizing this, the bladder 1 can be expanded in such a manner that the occurrence of air entry is suppressed. The width W3 of the reinforcing ply 3 and the portion where the reinforcing ply 3 is bonded are appropriately set in view of such circumstances, and are not limited to those shown in FIGS. Moreover, it is also possible to bond the reinforcement ply 3 to one or a plurality of parts by using a plurality of (for example, five or less) reinforcement plies 3.

  As shown in FIG. 3, in this embodiment, the cord C3 of the reinforcing ply 3 is inclined in the same direction as the cord C2 of the main body ply 2 (upward direction in FIG. 3). The direction of the code C <b> 2 here is specified not in the folded portion of the main body ply 2 but in other portions (portions constituting the entire bladder). In realizing the desired expansion and deformation, the cord C3 may be inclined in a direction crossing the cord C2.

  The bladder 1 may be provided with a reinforcing rubber tape 9 that is formed narrower than the main body ply 2 and is bonded to the main body ply 2. The reinforcing rubber tape 9 is a rubber single-layer member that does not include a cord, and the durability of the bladder 1 can be further improved by bonding the rubber tape 9 to a portion where the load due to repeated expansion and contraction is large. The reinforcing rubber tape 9 is bonded to the portion indicated by a broken line in FIG. This part is a part located on the outer peripheral side of the end part of the molding drum 7 when the end part of the carcass ply 6 is folded back as shown in FIG.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

  In order to confirm the configuration and effects of the present invention, turn-up bladders having the specifications shown in Table 1 were produced, the occurrence of air entering and the durability were investigated, and the material costs were compared. The material cost is expressed as an index when Example 1 is set to 100.

  In each example except the comparative example 2, the reinforcing ply was bonded to the end of the folded end portion of the main body ply as shown in FIG. Comparative Example 2 includes only a main body ply as a ply member and does not include a reinforcing ply. In Example 4, a reinforced rubber tape was bonded to the portion shown in FIG. In Example 5, a reinforcing ply was further added, and the ply was attached to a portion indicated by a broken line in FIG. The width and cord angle of the additional reinforcement ply are listed in brackets. The structure and rubber composition in each example are common with respect to the configuration that is not specified.

  Regarding suppression of air entry, Comparative Example 1 and Examples 3 to 6 were the most excellent, then Example 2 was excellent, and Comparative Example 2 was the worst. However, when the tire flatness is relatively low, Example 1 is more advantageous than Comparative Example 1 in which the effect of suppressing the outer diameter of the bladder during expansion is hardly obtained. More versatile than 1. In addition, with respect to durability, in Example 1, puncture occurred at the stage where 5000 to 6000 times of expansion was repeated, whereas the durability of Example 5 was about the same, and the durability of Example 6 was more than that. there were. Comparative Examples 1 and 2 and Examples 2 to 4 were less durable than Example 1, but Comparative Example 2 was particularly remarkable.

1 Turn-up bladder 2 Body ply 3 Reinforced ply 6 Carcass ply 7 Molding drum 9 Reinforced rubber tape 11 End 12 End 13 Bead C2 Code C3 Code θ2 Code angle θ3 Code angle

Claims (5)

In turn-up bladders used for tire molding,
A main body ply forming a skeleton of the bladder from one end to the other end, and a reinforcing ply formed narrower than the main body ply and bonded to the main body ply,
The main body ply and the reinforcing ply each include a cord that extends with an inclination with respect to the circumferential direction,
The turn-up bladder, wherein a cord angle of the reinforcing ply with respect to a circumferential direction is in a range of 50 to 90 degrees and is equal to or smaller than a cord angle of the main body ply with respect to the circumferential direction.   The turn-up bladder according to claim 1, wherein a cord angle of the reinforcing ply with respect to a circumferential direction is in a range of 80 to 90 degrees.   The turn-up bladder according to claim 1 or 2, wherein a difference between a cord angle of the reinforcing ply and a cord angle of the main body ply is within 10 degrees.   The turn-up bladder according to any one of claims 1 to 3, wherein the cord of the reinforcing ply is inclined in the same direction as the cord of the main body ply.   The turn-up bladder according to any one of claims 1 to 4, further comprising a reinforcing rubber tape formed narrower than the main body ply and bonded to the main body ply.

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