JP6255993B2 - Tire vulcanizing bladder - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a tire vulcanizing bladder, and more specifically, a tire vulcanization in which a temperature difference between an upper portion and a lower portion is reduced when vulcanizing a green tire that is set in a horizontal state in a mold. For bladders.

  When the pneumatic tire is vulcanized and molded, as shown in FIG. 5, after setting the green tire G in the mold 10, the vulcanizing bladder 1 is inserted into the green tire G, and the steam S In many cases, the green tire G is pressurized and heated by injecting, filling, and expanding. The green tire G is set horizontally in a mold 10 attached to the vulcanizing device 6, and the vulcanizing bladder 1 is arranged so that the cylinder axis direction is the vertical direction. The steam S expands the vulcanizing bladder 1 from the inside and presses and heats the green tire G between the inner surface of the mold 10. Along with this, the steam S is cooled and part of the steam S is condensed to become water, which adheres to the inner surface of the vulcanizing bladder 1. The adhering condensed water W flows down along the inner wall surface of the vulcanizing bladder and accumulates at the bottom. The condensed water W collected at the bottom may form an annular band.

  A region where condensed water is accumulated at the bottom of the vulcanizing bladder is a portion corresponding to the bead portion from the shoulder portion around the side portion of the pneumatic tire. Since the temperature of the condensed water is lower than the temperature of the steam, the strength of heating in the region at the bottom of the bladder in contact with this is weaker than in other regions. That is, the temperature of the portion corresponding to the bead portion from the shoulder portion of the tire below the vulcanization bladder is lower than the temperature of the other portion, particularly the portion corresponding to the bead portion from the shoulder portion above the vulcanization bladder. There is concern that it may affect tire quality and productivity.

  For this reason, Patent Documents 1 and 2 propose that the temperature in the upper and lower regions of the vulcanizing bladder is reduced by mixing the steam by causing convection in the steam in the vulcanizing bladder to make the temperature uniform. However, in these methods, it is difficult to completely eliminate the condensation of steam, and the problem concerning the condensed water has not been solved. Patent Document 3 proposes that a drain pipe is provided in the mold and the accumulated condensed water is discharged to the outside. However, the condensed water produced during one vulcanization cycle cannot be completely removed.

  All of the methods described in Patent Documents 1 to 3 involve installation work of a mold and / or a vulcanizer, and there is a problem that the production cost increases when applied to an existing mold and vulcanizer. Further, in order to stably produce high quality pneumatic tires, further improvement of the vulcanizing bladder has been demanded.

JP 2012-218299 A JP2013-159049A JP 2003-326526 A

    An object of the present invention is to provide a tire vulcanization bladder that reduces a temperature difference between an upper portion and a lower portion of a tire vulcanization bladder when a green tie is vulcanized in order to solve the above-described problems. It is in.

A tire vulcanizing bladder according to the present invention that achieves the above object is a tire vulcanizing bladder used when vulcanizing a green tire that is set horizontally in a mold, wherein at least the tire on the inner surface of the bladder is used. A plurality of rubber ribs extending in a direction inclined with respect to the tire meridian are formed in a portion corresponding to the shoulder portion on the lower side from the center at intervals in the tire circumferential direction, and on the lower side of the inner surface of the bladder. A plurality of rubber protrusions are formed at intervals in the tire circumferential direction from the shoulder portion to the bead portion, and the direction in which the rubber protrusion protrudes is inclined toward the inclination direction of the rib. It is characterized by.

  According to the present invention, a plurality of rubber ribs inclined with respect to the tire meridian are arranged at intervals in the tire circumferential direction on a portion corresponding to the shoulder portion on the lower side from the tire center on the inner surface of the tire vulcanizing bladder. Therefore, the condensed water adhering to the inner surface of the bladder at the time of vulcanization flows downward along the inclined rib, and when it reaches the bottom of the bladder, it flows in the direction induced in the inclination direction of the rib. As a result, convection and mixing in the depth direction occur in the condensed water accumulated at the bottom, and the temperature of the condensed water that is in contact with the surface of the condensed water and the bladder, which is colder than the surface, becomes more uniform, and contacts the bladder for tire vulcanization. The surface temperature increases. As a result, the temperature difference between the upper portion and the lower portion of the tire vulcanizing bladder can be reduced, and a high-quality pneumatic tire can be stably manufactured. Moreover, since only the inclined rib is formed on the inner surface, the bladder for tire vulcanization can be improved easily and at low cost.

The inner surface of the tire vulcanizing bladder, the portion corresponding to the bead portion from the shoulder portion of the lower, multiply formed at intervals the rubber projections in the tire circumferential direction. Thereby, the mixing of the up-down direction in the condensed water collected on the bottom part can be accelerated | stimulated, and the temperature of condensed water can be equalize | homogenized.

Also the direction in which the rubber projections formed on the bladder bottom protrudes, Ru tilted toward the tilted direction of the ribs. According to this specification, since the protrusion protrudes in a direction opposite to the flow direction of the condensed water at the bottom of the bladder, mixing in the vertical direction in the condensed water can be further promoted.

  The method for producing a pneumatic tire according to the present invention can stably produce a high-quality pneumatic tire by vulcanizing a green tire using the tire vulcanizing bladder described above.

It is explanatory drawing which shows an example of embodiment of the bladder for tire vulcanization | cure of this invention in a meridian direction cross section. It is explanatory drawing which shows the other example of embodiment of the bladder for tire vulcanization | cure of this invention in a meridian direction cross section. (A) (b) (c) is a part of the expanded view which illustrates embodiment of the rib and protrusion which are formed in the inner surface of the bladder for tire vulcanization, respectively. 4A is an explanatory view schematically showing the flow of condensed water at the bottom of the bladder, and FIGS. 4B and 4C are cross-sectional views taken along the line XX in FIG. It is explanatory drawing which shows the conventional bladder for tire vulcanization with the half cross section of a meridian direction.

  Hereinafter, a tire vulcanizing bladder according to the present invention will be described based on an embodiment shown in the drawings.

  A vulcanizing bladder 1 of the present invention illustrated in FIG. 1 (hereinafter referred to as a bladder 1) is made of rubber made of butyl rubber or the like and is formed in a substantially cylindrical shape. The film thickness of the bladder main body portion 2 is a predetermined substantially constant thickness, and both upper end portions (opening edge portions) in the cylinder axis direction are formed to be thicker than the film thickness of the bladder main body portion 2. 3a and the lower clamp part 3b.

  The bladder 1 is attached to the central mechanism 7 of the vulcanizer. Specifically, the upper clamp portion 3a and the lower clamp portion 3b of the bladder 1 are respectively held by disk-shaped upper holding portions 8a and lower holding portions 8b attached to the center post of the center mechanism 7. An injection nozzle 9 a for injecting steam into the bladder 1 is provided at the center post of the center mechanism 7.

  In the bladder 1 of the present invention, a plurality of rubber ribs 11 are formed at intervals in the tire circumferential direction in a portion corresponding to the lower shoulder portion Z2 from the tire center Z1 on the inner surface thereof. The rib 11 extends in a direction inclined with respect to the tire meridian, the upper end thereof is on the upper side including a portion corresponding to the tire center Z1, and the lower end portion is on a portion corresponding to the shoulder portion Z2.

  By disposing the ribs 11, a unidirectional flow can be caused in the condensed water. Specifically, when vulcanizing a green tire, steam condenses in the bladder and condensed water adheres to the wall surface. The adhered water droplets travel down the wall surface of the bladder due to gravity and reach the ribs 11. Thereafter, the condensed water droplets flow downward along the inclined ribs. Thereby, the flow of one direction arises in condensed water. This flow is maintained even when the condensed water reaches the bottom of the bladder and flows in a certain direction guided by the ribs 11.

  If there is a flow in the condensate at the bottom of the bladder, convection will occur in it and the temperature of the condensate will be uniform. For example, if condensed water accumulates at the bottom of the bladder and the condensed water does not flow and stays in one place, the layer of condensed water in contact with the bottom of the bladder is further cooled, and as a result, the bottom of the bladder moves from the inside to the outside. Heat transfer action is reduced. For this reason, the temperature difference between the bottom part on the lower side of the bladder in contact with the condensed water and the other part, for example, the ceiling part on the upper side of the bladder becomes large. On the other hand, since the condensed water has a flow as in the present invention, convection occurs in the vertical direction in addition to the flow direction, so that the temperature of the condensed water becomes uniform. As a result, the temperature of the condensed water in contact with the bottom surface of the bladder increases, and the heat transfer action from the inside to the outside at the bottom of the bladder increases. For this reason, the temperature difference between the bottom part on the lower side of the bladder and other regions, for example, the ceiling part on the upper side of the bladder can be reduced.

  In the present invention, the rib 11 extends in a direction inclined with respect to the tire meridian. The angle θ to be inclined with respect to the tire meridian is not particularly limited as long as the condensed water droplets can be efficiently transmitted, but is preferably 5 to 60 °, more preferably 30 to 45 with respect to the tire meridian. It should be °. The inclination angle with respect to the tire meridian is representative of the angle at the portion corresponding to the tire center Z1 on the inner surface of the bladder.

  A plurality of ribs 11 are formed at intervals over one circumference in the bladder. The interval at which the ribs 11 are formed in the circumferential direction is determined so that an arbitrary point on the circumference of the bladder inner surface corresponding to the tire center intersects at least one rib 11 on the meridional section including that point. it can. By disposing the ribs 11 in this way, it is possible to reliably receive the condensed water droplets that adhere to and propagate to any point on the inner surface of the bladder. The circumferential interval between the ribs 11 can be appropriately set depending on the size of the green tire to which the bladder 1 is applied (outer diameter, cross-sectional width, cross-sectional height, flatness ratio, etc.), but preferably 3 to 30 mm. Preferably it is 5-15 mm.

  The rib 11 can be integrally formed with the bladder main body 2 by rubber constituting the bladder main body 2. The shape of the rib 11 is not particularly limited as long as the condensed water can be received and efficiently transferred. Examples of the cross-sectional shape of the rib 11 include a (right-angle) triangle, a rectangle, and a trapezoid. Of these, a right triangle and a rectangle are preferable. The height of the rib 11 (the length protruding from the bladder main body) is preferably 0.1 to 1.0 mm, more preferably 0.2 to 0.5 mm. By setting the height of the rib 11 within such a range, it is possible to receive a drop of condensed water that naturally descends and transmit it in the inclined direction.

In the present invention, the portion corresponding to the bead portion from the lower shoulder portion of the inner surface of the bladder 1, multiply formed at intervals the rubber projections in the tire circumferential direction. Thereby, the stirring effect of the up-down direction can be added to the flow of condensed water, and the temperature of condensed water can be made more uniform. For example, as shown in FIG. 2, that form a rubber protrusions 12 from the shoulder portion Z2 of the lower inner surface of the bladder 1 in a portion corresponding to a bead portion Z3. Projection 12 is, you multiply formed at intervals in the tire circumferential direction. In the illustrated example, the condensed water having a unidirectional flow by the ribs 11 flows from the back of the paper to the front at the left bottom of the bladder and from the front of the paper to the back at the bottom of the right. On the other hand, by disposing the protrusion 12 at the bottom, the flow of the condensed water can be disturbed, and the convection of the condensed water can be promoted to make the temperature uniform.

  The shape of the protrusion 12 may be any one of a protrusion continuously extending from the shoulder portion to the bead portion, a protrusion extending intermittently or discontinuously, or a protrusion scattered regularly or irregularly. Moreover, the combination of these two or more forms may be sufficient. However, the size (height, length) of the protrusion 12 should not completely stop the flow of condensed water. The size of the protrusion 12 can be set as appropriate according to the size of the green tire to which the bladder 1 is applied, the internal volume of the bladder 1, the vulcanization conditions (steam temperature, pressure, vulcanization time, etc.), and the like. The height of the protrusion 12 is preferably 0.1 to 1.0 mm, and more preferably 0.2 to 0.5 mm.

  FIGS. 3A, 3B, and 3C are development views of a part of the inner surface of the bladder. The rib 11 and the protrusion 12 are formed at a portion corresponding to the bead portion Z3 from the tire center Z1 through the lower shoulder portion Z2. It is explanatory drawing which shows the embodiment arrange | positioned typically.

  In FIG. 3A, a plurality of ribs 11 inclined at an angle θ with respect to the tire meridian are arranged at intervals in the tire circumferential direction in a portion corresponding to the shoulder portion Z2 below the tire center Z1 on the inner surface of the bladder. Yes. A plurality of protrusions 12 are arranged at intervals in the tire circumferential direction from the lower shoulder portion Z2 to the portion Z3 corresponding to the bead portion, that is, the bottom portion of the cylindrical bladder. In the illustrated example, the plurality of protrusions 12 are formed as continuous ridges extending substantially radially from the center of the cylinder axis. When the continuous protrusion as the protrusion 12 is erected at the bottom, the flow of the condensed water can be prevented from clogging by reducing the height.

  Moreover, as shown in FIG.3 (b), the some protrusion 12 can also be formed in the short protrusion extended from the center of a cylinder axis substantially radially. In the illustrated example, short ridges are arranged in three rows, and the arrangement of the middle row is shifted in the circumferential direction. As a result, the flow of the condensed water is prevented from being blocked, and the flow of the right and left short ridges is generated, so that the convection of the condensed water is promoted and the temperature of the condensed water can be made more uniform.

  FIG. 3C shows an example in which the plurality of protrusions 12 are formed so as to be square in plan view. This specification can prevent the flow of condensed water from clogging. The shape of the projection in plan view can be any shape such as a triangle, a rectangle, a trapezoid, a rhombus, another polygon, a circle, and an indeterminate shape in addition to the illustrated example.

In the present invention, a direction of projecting the projection 12 from the inner surface of the bladder body portion 2, Ru inclined towards the direction of inclination of the rib 11. For example, it is assumed that the flow of condensed water that has reached the bottom of the bladder through the rib 11 flows in the direction of arrow f as schematically shown in FIG. With respect to the flow in the f direction, as shown in FIG. 4B, the plurality of protrusions 12 are inclined toward the inclination direction of the ribs 11, that is, the inclination of the wall surface on the upstream side of the protrusions 12 is the inclination direction of the ribs 11. It is preferable to stand up so as to be approximately parallel to. As shown in the figure, the protrusion 12 is inclined and protruded so as to be opposite to the flow direction f of the condensed water, thereby promoting the vertical flow of the water layer and making the temperature of the condensed water more uniform. it can.

  On the other hand, as shown in FIG. 4 (c), when the protrusion 12 is tilted so as to be forward with respect to the flow direction f of the condensed water, the convection in the vertical direction in the condensed water layer is strengthened. It is not expected as much as the protrusion 12 of (b).

  4B and 4C are cross-sectional views taken along the line XX of FIG. 2 and schematically illustrate the direction in which the protrusion 12 is inclined and protruded with respect to the flow direction f of the condensed water. In the illustrated example, the cross-sectional shape of the protrusion 12 is a triangle, but other cross-sectional shapes may be used as described above. In addition, the angle at which the protrusion 12 is inclined and protruded is an angle formed by the wall surface of the protrusion 12 and the bladder main body 2 on the upstream side with respect to the flow direction f.

  A high-quality pneumatic tire can be stably produced by vulcanizing a green tire using the tire vulcanizing bladder described above. In the method for manufacturing a pneumatic tire according to the present invention, the bladder 1 is inserted into a green tire G set in a horizontal state in a mold 10 installed in a vulcanizing device 6 and vulcanized. The green tire G is arranged inside the opened mold 10 and the bladder 1 is inserted inside thereof. Next, the mold 10 is closed, and steam S is injected and filled into the bladder 1 from the injection nozzle 9a, and the bladder main body 2 is expanded and heated while pressing the inner surface of the green tire G. Since the steam S is deprived of thermal energy through expansion and heating, a part of the steam S is condensed and adheres to the inner surface of the bladder body 2 as water droplets. This water droplet grows, travels down along the inner surface of the bladder main body 2, and is received by the rib 11. The condensed water collected by the ribs 11 flows downward in the inclined direction, and the flow is maintained even when reaching the bottom of the bladder. Thereby, convection is generated inside the condensed water, the temperature becomes uniform in the vertical direction, and the temperature at the bottom of the bladder can be increased. Along with this, the temperature difference between the bottom part of the lower side of the bladder and the other part, for example, the ceiling part of the upper side of the bladder is reduced, and the vulcanized state of the green tire can be made more uniform, and high quality air can be obtained. The entering tire can be manufactured stably.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  When vulcanizing tires with the same specifications (195 / 65R15), 6 types of bladders (Examples 1 to 3 and Comparative Examples 1 to 3) with different specifications of ribs and protrusions as shown in Table 1 are used. Then, a pneumatic tire was manufactured using steam (1.6 MPa) under a vulcanization time of 600 seconds. During vulcanization, the temperature of the bottom and ceiling of the bladder was measured and the maximum temperature difference was calculated. The obtained results are shown in the column of “Temperature difference” in Table 1 using an index with the result of Comparative Example 1 as 100. The smaller this index is, the lower the temperature at the bottom and ceiling of the bladder.

  The ribs 11 of Examples 1 to 3 are ribs that are disposed in a portion corresponding to the shoulder portion on the lower side from the tire center, have an inclination angle θ with respect to the tire meridian of 35 °, a height of 0.5 mm, and a semicircular cross-sectional shape. There are 10 mm intervals in the tire circumferential direction.

Projection 12a of Example 2 and Comparative Example 2, the height 0.3mm arranged in a portion corresponding to the bead portion from the shoulder, length 80 mm, the flow as shown in FIG. 4 (c) a triangular cross section a projection provided upright on the forward first direction f, the inclination angle of the lower stream side of the inclination angle of 60 ° and on the upstream side with respect to the bladder bottom section (horizontal plane) is 45 °. The circumferential interval between the protrusions 12a was 10 mm at the center in the length direction.

Protrusions 12b of Example 3 and Comparative Example 3, the height 0.3mm arranged in a portion corresponding to the bead portion from the shoulder, length 80 mm, the flow as shown in FIG. 4 (b) is a triangular cross section a projection provided upright on the barb in the direction f, the inclination angle of the lower stream side is 45 ° to the bladder bottom section (horizontal plane). The circumferential interval between the protrusions 12b was 10 mm at the center in the length direction.

DESCRIPTION OF SYMBOLS 1 Bladder 2 Bladder body part 3a Upper clamp part 3b Lower clamp part 6 Vulcanizing device 7 Central mechanism 8a Upper holding part 8b Lower holding part 9a Injection nozzle 10, 10a, 10b, 10c, 10d Mold 11 Rib 12 Protrusion G Green Tire S Steam W Condensate Z1 Tire Center Z2 Shoulder Z3 Bead

Claims (2)

In a tire vulcanizing bladder used for vulcanizing a green tire set in a horizontal state in a mold, at least a portion corresponding to a shoulder portion on the lower side from the tire center of the inner surface of the bladder is a tire meridian A plurality of rubber ribs extending in a direction inclined with respect to the tire are formed at intervals in the tire circumferential direction, and a rubber protrusion is formed on the portion corresponding to the bead portion from the lower shoulder portion of the inner surface of the bladder. A tire vulcanization bladder characterized in that a plurality of tires are formed at intervals in the tire circumferential direction, and a direction in which the rubber protrusion protrudes is inclined toward an inclination direction of the rib . A method for producing a pneumatic tire in which a green tire is vulcanized using the tire vulcanizing bladder according to claim 1 .

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