JP5640668B2 - Tire vulcanization mold and pneumatic tire - Google Patents

Description

  The present invention relates to a tire vulcanization mold capable of sufficiently suppressing uneven wear of a vulcanized tire while preventing problems in the vulcanization process caused by lateral groove protrusions disposed in the vicinity of the divisional position of the sectional mold. It relates to pneumatic tires.

  In the sectional mold for vulcanizing a pneumatic tire, as shown in FIG. 7, various lateral groove protrusions 3, circumferential groove protrusions, and sipe blades 5 protrude from the tire molding surface 2. For example, the lateral groove protrusions 3 and the sipe blades 5 are arranged at a predetermined pitch in the tire circumferential direction. Therefore, in some cases, the lateral groove protrusion 3 and the sipe blade 5 may be arranged so as to straddle the division position PL of the sector 1.

  If the horizontal groove protrusion 3 is applied to the division position PL of the sector 1, the structure of the horizontal groove protrusion 3 is divided into two. For this reason, when the mold is closed by moving the sector 1 in a reduced diameter, a so-called rubber bite is generated in which the unvulcanized rubber of the green tire 6 disposed inside the mold is sandwiched between the projections 3 for the lateral grooves divided into two. It becomes easy to do. In particular, rubber biting is likely to occur at the tire shoulder. When rubber biting occurs, film-like burrs are generated on the vulcanized tire, resulting in defects such as poor appearance and poor drainage. Therefore, a great amount of work and cost are required to remove these burrs. It was. Further, since the lateral groove protrusion gradually divided into two parts due to the rubber bite is generated, it is necessary to periodically perform repairs to eliminate the opening, which requires a great amount of work and cost.

  Therefore, the horizontal groove protrusion divided at the dividing position PL is simply moved to move away from the dividing position PL, and the protrusion at the dividing position PL of the horizontal groove protrusion is simply erased. A method has been proposed in which the height of the protrusion at the position PL is lowered (for example, see Patent Document 1). However, in these proposals, in the vulcanized tire, the change in the block rigidity of the tire is caused by the modified lateral groove protrusion and another lateral groove protrusion (original lateral groove protrusion) adjacent to the lateral groove protrusion. There is a problem that uneven wear cannot be sufficiently suppressed. Further, when the lateral groove protrusion is moved in parallel or partially removed, the appearance is remarkably impaired. If the projection height of a part of the lateral groove projections is lowered, rubber biting may not be completely prevented, and it may appear that the tires are unevenly worn as the tire wears.

  Further, since the sipe blade 5 protrudes in a direction perpendicular to the tread surface of the tire (that is, a direction orthogonal to the tire molding surface 2), the sipe blade 5 protrudes in the center in the circumferential direction of the tire molding surface 2 of the sector 1. The sipe blade 5 is oriented almost parallel to the expansion / contraction movement direction of the sector 1, but the direction of the sipe blade 5 protruding near the division position PL of the sector 1 (both ends in the circumferential direction of the sector 1) is The direction of expansion / contraction movement of sector 1 is not parallel and has a certain degree of angle. Therefore, an external force (bending moment) is likely to act on the sipe blade 5 projecting in the vicinity of the division position PL of the sector 1 when the sector 1 is expanded in diameter and opened. Therefore, in the vicinity of the division position PL of the sector 1, the closer to the division position PL, the more easily the sipe blade 5 is detached and damaged from the tire molding surface 2 by an unnecessary external force, and the tire at the root of the sipe blade 5 There was a problem that the molding surface 2 was easily damaged. However, in the lateral groove protrusion 3 in which the sipe blade 5 is continuously provided, if the lateral groove protrusion 3 is simply deformed and moved in order to move the sipe blade 5 away from the division position PL, the lateral groove whose specifications have been changed as described above. The change in tire block stiffness may increase due to the projection for use and another lateral groove projection adjacent to the lateral groove projection (original lateral groove projection), and uneven wear cannot be sufficiently suppressed. was there.

JP-A-3-42305

  An object of the present invention is for tire vulcanization, which can sufficiently suppress uneven wear of a vulcanized tire while preventing problems in the vulcanization process caused by lateral groove protrusions arranged in the vicinity of the divisional position of the sectional mold. It is to provide a mold and a pneumatic tire.

  In order to achieve the above object, a tire vulcanization mold of the present invention is a sectional type tire vulcanization mold provided with a lateral groove protrusion projecting on a tire molding surface of a sector. For the horizontal groove protrusions that hang on the split position, change the protrusion shape by changing the protrusion direction in the middle of the protrusion length direction so that it does not reach the split position. The length L1 and the protrusion peripheral edge length L2 of the portion whose shape has been changed are in a relationship of L2 / L1 ≦ 9, and the area S2 of the lateral groove protrusion after the shape change is the area S1 of the original shape horizontal groove protrusion. 70% to 120%.

  Another tire vulcanization mold according to the present invention is a sectional type tire vulcanization mold having a lateral groove projection that is provided with a sipe blade projecting on a tire molding surface of a sector. In the original shape, the sipe blades that are provided continuously hit the division position of the sector, or for the protrusions for lateral grooves whose distance from the division position is less than 1.5 mm, the direction of the protrusions in the middle of the protrusion length direction The protrusion shape is changed by changing the distance between the blade and the split position to 1.5 mm or more, and the protrusion peripheral edge length L1 of the original portion and the protrusion of the changed portion of the lateral groove protrusion after the shape change are changed. The peripheral length L2 has a relationship of L2 / L1 ≦ 9.

  The pneumatic tire of the present invention is characterized by being vulcanized using the tire vulcanization mold described above.

  According to the former tire vulcanization mold of the present invention, the direction of the protrusions in the protrusion length direction is changed so that the protrusions for the horizontal grooves that are applied to the sector dividing position in the original shape are not applied to the dividing position. By changing the protrusion shape, it is possible to prevent the lateral groove protrusion from engaging with the rubber of the green tire when the mold is closed. And about the protrusion for horizontal grooves after the shape change, the protrusion peripheral length L1 of the original portion and the protrusion peripheral length L2 of the shape changed portion have a relationship of L2 / L1 ≦ 9, and the horizontal groove after the shape change Since the area S2 of the projection is 70% to 120% of the area S1 of the original-shaped lateral groove protrusion, the specification change with the adjacent original-shaped lateral groove protrusion is limited to a certain range. In the tire, the change in the block rigidity of the tire due to the lateral grooves is reduced, and the uneven wear of the tire can be sufficiently suppressed.

  According to the latter tire vulcanization mold of the present invention, the sipe blades that are continuously provided with the lateral groove protrusions in the original shape are applied to the division position of the sector, or the distance to the division position is less than 1.5 mm. For the lateral groove protrusion, change the protrusion shape in the middle of the length direction to change the protrusion shape, and make the distance between the blade and the split position 1.5 mm or more. Unnecessary external force acting on the blade can be reduced. Thereby, the sipe blade can be prevented from being detached or damaged. Then, with respect to the lateral groove protrusion after the shape change, the adjacent peripheral original with a specification in which the protrusion peripheral length L1 of the original portion and the protrusion peripheral length L2 of the changed portion have a relationship of L2 / L1 ≦ 9 Since the change in specifications with the shape of the lateral groove protrusion is limited to a certain range, in a vulcanized tire, the change in the tire block rigidity due to the lateral groove is reduced, and the uneven wear of the tire can be sufficiently suppressed. .

  In the former tire vulcanization mold of the present invention, it is more preferable that the protrusion peripheral length L1 of the original portion and the protrusion peripheral length L2 of the shape-changed portion have a relationship of L2 / L1 ≦ 2. Thereby, in the vulcanized tire, the change in the block rigidity of the tire due to the lateral grooves is further reduced, which is further advantageous in suppressing uneven wear of the tire. More preferably, the specification is such that the area S2 of the lateral groove protrusion after the shape change is 95% to 105% of the area S1 of the original shape lateral groove protrusion. Thereby, in the vulcanized tire, the change in the block rigidity of the tire due to the lateral grooves is further reduced, which is further advantageous in suppressing uneven wear of the tire. Further, for example, the lateral groove protrusion forms a lateral groove of the tire shoulder portion. The portion of the tire shoulder portion where the lateral groove is formed is a place where rubber biting of the green tire is likely to occur. Therefore, it is more advantageous to apply the present invention.

  In the latter tire vulcanization mold of the present invention, the protrusion peripheral length L1 of the original portion and the protrusion peripheral length L2 of the modified portion have a relationship of L2 / L1 ≦ 2, and the shape change It is more preferable that the area S2 of the subsequent lateral groove protrusion is 70% to 120% of the area S1 of the original lateral groove protrusion. Thereby, in the vulcanized tire, the change in the block rigidity of the tire due to the lateral grooves is further reduced, which is further advantageous in suppressing uneven wear of the tire. More preferably, the specification is such that the area S2 of the lateral groove protrusion after the shape change is 95% to 105% of the area S1 of the original shape lateral groove protrusion. Thereby, in the vulcanized tire, the change in the block rigidity of the tire due to the lateral grooves is further reduced, which is further advantageous in suppressing uneven wear of the tire.

  In the pneumatic tire of the present invention, appearance defects caused by rubber biting are eliminated, and uneven wear of the tire can be suppressed.

It is a top view which illustrates partially expanding the tire molding surface of the mold for tire vulcanization of the present invention. It is explanatory drawing which illustrates the protrusion for horizontal grooves which carried out specification change. FIG. 2 is a plan view illustrating a part of a tread of a tire vulcanized using the mold of FIG. 1. FIG. 6 is a plan view illustrating a partially enlarged tire molding surface of another tire vulcanization mold of the present invention. It is explanatory drawing which illustrates the protrusion for horizontal grooves which carried out specification change. FIG. 5 is a plan view illustrating a part of a tread of a tire vulcanized using the mold of FIG. 4. It is a side view which illustrates a sector.

  Hereinafter, the mold for tire vulcanization of the present invention is explained based on the embodiment shown in the figure.

  The tire vulcanization mold of the present invention (hereinafter referred to as a mold) is of a sectional type as illustrated in FIG. 7 and includes a plurality of arcuate sectors 1 that are assembled to form an annular shape. Each sector 1 moves in the radial direction of the ring so as to expand and contract the ring.

  As illustrated in FIGS. 1 and 2, a lateral groove protrusion 3 and a circumferential groove protrusion 4 project from the tire molding surface 2. The sector 1, the groove forming protrusion 3 and the circumferential protrusion 4 are a single piece cast from a metal such as aluminum. The lateral groove protrusions 3 are arranged at a predetermined constant pitch in the circumferential direction of the sector 1 (left and right direction in FIG. 1). The lateral groove protrusion 3 is a protrusion that forms a lateral groove 8 (a groove other than the circumferential groove 9) extending in the tire width direction on the vulcanized tire 7.

  In the present invention, with the original shape 3a, the shape (arrangement) of the lateral groove protrusion 3 that is applied to the division position PL of the sector 1 is partially changed. The horizontal groove protrusions 3 applied to the division position PL refer to the horizontal groove protrusions 3 arranged across the division position PL when arranged at a predetermined constant pitch in the circumferential direction of the sector 1. The lateral groove protrusion 3 is not limited to a simple linear shape, but may have a curved shape or various shapes.

  If the original shape 3a indicated by the two-dot chain line remains as it is, the lateral groove protrusion 3 that is applied to the division position PL of the sector 1 is limited to a certain range in the specification change with the adjacent horizontal groove protrusion 3 of the original shape 3a. The protrusion shape is changed by changing the direction of the protrusion in the middle of the protrusion length direction so as not to reach the dividing position PL. Specifically, with respect to the lateral groove protrusion 3 after the shape change, the protrusion peripheral length L1 of the original portion and the protrusion peripheral length L2 of the shape changed portion have a relationship of L2 / L1 ≦ 9. If L2 / L1> 9, the shape change range for the original shape 3a becomes excessive, which is not preferable.

  Further, the area S2 in plan view of the lateral groove protrusion 3 after the shape change is set to 70% to 120% of the area S1 in plan view of the lateral groove protrusion 3 of the original shape 3a. If this ratio is less than 70% or more than 120%, the shape change with respect to the original shape 3a becomes excessive, which is not preferable. Note that the height of the protrusion is not changed between the lateral groove protrusion 3 after the shape change and the lateral groove protrusion 3 of the original shape 3a. In this embodiment, the deformed portion is changed so as to be along the division position PL without being applied to the division position PL.

  Thus, since the shape of the horizontal groove protrusion 3 is changed so as not to reach the dividing position PL, the horizontal groove protrusion 3 is not divided into two at the dividing position PL. Therefore, when the sector 1 is closed, the lateral groove protrusion 3 does not engage the rubber of the green tire 6.

  By vulcanizing the green tire 6 using the sector 1 (mold), the tire 7 in which the lateral groove 8 and the circumferential groove 9 illustrated in FIG. 3 are formed is manufactured. Further, L2 / L1 ≦ 9 and the area S2 of the lateral groove protrusion 3 after the shape change is set to 70% to 120% of the area S1 of the lateral groove protrusion 3 of the original shape 3a. Variation in the block rigidity of the tire 7 in which the lateral grooves 8 are formed by the projections 3 and the lateral groove protrusions 3 of the original shape 3a is corrected. That is, the change in the block rigidity of the tire 7 due to the lateral grooves 8 is reduced, and the uneven wear of the tire 7 can be sufficiently suppressed.

  More preferably, L2 / L1 ≦ 2. Thereby, in the vulcanized tire 7, the change in the block rigidity of the tire 7 due to the lateral grooves 8 is further reduced, which is further advantageous in suppressing uneven wear of the tire 7.

  More preferably, the area S2 of the lateral groove protrusion 3 after the shape change is 95% to 105% of the area S1 of the lateral groove protrusion 3 of the original shape 3a. Thereby, in the vulcanized tire 7, the change in the block rigidity of the tire 7 due to the lateral grooves 8 is further reduced, which is further advantageous in suppressing uneven wear of the tire 7.

  A portion of the tire shoulder portion where the lateral groove 8 is formed is a place where the rubber biting of the green tire 6 is likely to occur. Therefore, it is more beneficial to change the specifications of the lateral groove protrusions 3 forming the lateral grooves 8 of the tire shoulder portion as described above.

  In the pneumatic tire 7 of the present invention vulcanized using the sector 1 (mold), the appearance defect caused by the rubber engagement is eliminated, and uneven wear can be suppressed.

  When other groove protrusions are connected to the lateral groove protrusion 3 whose specifications are changed, the groove protrusions are extended or shortened as they are with respect to the lateral groove protrusions 3 whose specifications are changed. And let it run naturally.

  FIG. 4 and FIG. 5 illustrate another embodiment. On the tire molding surface 2 of the sector 1, a lateral groove projection 3 and a circumferential groove projection 4 are provided so as to project a sipe blade 5. The lateral groove protrusions 3 are arranged at a predetermined constant pitch in the circumferential direction of the sector 1 (left-right direction in FIG. 4). The lateral groove protrusion 3 and the circumferential groove protrusion 4 protrude upward from the tire molding surface 2 relative to the sipe blade 5.

  The sipe blade 5 is made of a metal such as stainless steel, general carbon steel, or iron. Although the size of the sipe blade 5 varies depending on the tire size, the total length is, for example, 3 mm to 100 mm, and the thickness is, for example, about 0.4 mm to 2.0 mm, which is thinner than the lateral groove protrusion 3. The sipe blade 5 is not limited to a simple linear shape, but may be a zigzag specification having a plurality of bending points.

  In the present invention, the sipe blades 5 that are connected to each other with the original shape 3a shown by the two-dot chain line in the horizontal groove projection 3 are applied to the division position PL of the sector 1, or the distance H ( For the horizontal groove protrusion 3 having a shortest distance (less than 1.5 mm), the specification change with the adjacent horizontal groove protrusion 3 of the original shape 3a is limited to a certain range, and the protrusion direction is changed in the middle of the protrusion length direction. The protrusion shape has been changed.

  Specifically, the distance h (shortest distance) between the sipe blade 5 and the division position PL is set to 1.5 mm or more by changing the shape of the lateral groove protrusion 3. For example, the distance h is set to 1.5 mm or more and 3.0 mm or less.

  In addition, with respect to the lateral groove protrusion 3 after the shape change, the protrusion peripheral length L1 of the original portion and the protrusion peripheral length L2 of the shape changed portion have a relationship of L2 / L1 ≦ 9. If L2 / L1> 9, the shape change range for the original shape 3a becomes excessive, which is not preferable. Note that the height of the protrusion is not changed between the lateral groove protrusion 3 after the shape change and the lateral groove protrusion 3 of the original shape 3a. Further, the thickness of the sipe blade 5 is not changed, and the length is set to be substantially the same. In this embodiment, along with the deformation of the lateral groove protrusion 3, the continuous sipe blade 5 is deformed so as to extend parallel to the division position PL.

  Thus, since the sipe blade 5 is separated from the dividing position PL by 1.5 mm or more, unnecessary external force acting on the sipe blade 5 is reduced when the sector 1 is opened after the green tire 6 is vulcanized. it can. Thereby, the sipe blade 5 can be prevented from being detached or damaged.

  By vulcanizing the green tire 6 using the sector 1 (mold), the tire 7 in which the lateral groove 8 and the circumferential groove 9 in which the sipe 10 illustrated in FIG. 6 is provided is formed. Since L2 / L1 ≦ 9, the variation in block rigidity of the tire 7 in which the lateral groove 8 is formed by the lateral groove projection 3 whose specification has been changed and the lateral groove projection 3 of the original shape 3a is corrected. That is, the change in the block rigidity of the tire 7 due to the lateral grooves 8 is reduced, and the uneven wear of the tire 7 can be sufficiently suppressed.

  More preferably, L2 / L1 ≦ 2, and the planar area S2 of the lateral groove protrusion 3 after the shape change is set to 70% to 120% of the planar area S1 of the lateral groove protrusion 3 of the original shape 3a. . Thereby, in the vulcanized tire 7, the change in the block rigidity of the tire 7 due to the lateral grooves 8 is further reduced, which is advantageous in suppressing uneven wear of the tire 7. If the area S2 is less than 70% or more than 120% of the area S1, the shape change with respect to the original shape 3a becomes excessive, which is not preferable.

  More preferably, the area S2 of the lateral groove protrusion 3 after the shape change is 95% to 105% of the area S1 of the lateral groove protrusion 3 of the original shape 3a. Thereby, in the vulcanized tire 7, the change in the block rigidity of the tire 7 due to the lateral grooves 8 is further reduced, which is further advantageous in suppressing uneven wear of the tire 7.

  With the original shape, the specifications for the vulcanization mold for the same type of passenger car tire that has the projections for the lateral grooves at the sector division position PL are as shown in Table 1 so that the projections for the lateral grooves do not enter the division position PL. 6 types of vulcanization molds were produced by changing the shape of the mold. And the tire for passenger cars (Examples 1-4, Comparative Examples 1 and 2) was manufactured using each vulcanization | molding mold, it traveled 1500km with each tire, and uneven wear was evaluated. Table 1 shows the result of the index evaluation with the condition of no uneven wear as the standard 100. A larger value indicates less uneven wear.

  L2 / L1 is the ratio of the protrusion peripheral length L2 of the portion where the shape of the lateral groove protrusion is changed to the protrusion peripheral length L1 of the original portion.

  S2 / S1 is a ratio (percentage) between the area S2 of the lateral groove protrusion after the shape change and the area S1 of the original lateral groove protrusion.

  From the results in Table 1, it can be seen that Examples 1-4 have less uneven wear on the tires than Comparative Examples 1 and 2.

DESCRIPTION OF SYMBOLS 1 Sector 2 Tire molding surface 3 Protrusion for horizontal groove 3a Original shape 4 Protrusion for circumferential groove 5 Sipe blade 6 Green tire 7 Vulcanized tire 7a Block 8 Horizontal groove 9 Circumferential groove 10 Sipe

Claims (8)

  In a sectional type tire vulcanization mold provided with projections for transverse grooves protruding from the tire molding surface of the sector, the projections for transverse grooves that are applied to the division position of the sector in the original shape are not applied to the division position. Thus, the projection shape is changed by changing the direction of the projection in the middle of the projection length direction, and for the lateral groove projection after the shape change, the projection peripheral length L1 of the original portion and the projection peripheral length L2 of the changed portion Is a relationship of L2 / L1 ≦ 9, and the area S2 of the lateral groove protrusion after the shape change is 70% to 120% of the area S1 of the original shape lateral groove protrusion. .   2. The tire vulcanization mold according to claim 1, wherein the protrusion peripheral length L <b> 1 of the original portion and the protrusion peripheral length L <b> 2 of the shape-changed portion have a relationship of L2 / L1 ≦ 2.   The tire vulcanization mold according to claim 1 or 2, wherein an area S2 of the lateral groove protrusion after the shape change is 95% to 105% of an area S1 of the original lateral groove protrusion.   The mold for tire vulcanization according to any one of claims 1 to 3, wherein the lateral groove protrusion forms a lateral groove of a tire shoulder portion.   In a sectional type tire vulcanization mold having a lateral groove projection for continuously connecting a sipe blade projecting on the tire molding surface of the sector, the sipe blade for continuous connection with the lateral groove projection remains in the original shape. For horizontal groove protrusions that are at the division position of the sector or whose distance from the division position is less than 1.5 mm, change the protrusion direction in the middle of the protrusion length direction to change the protrusion shape, and the blade and the division The relationship between the protrusion peripheral length L1 of the original part and the protrusion peripheral length L2 of the part whose shape has been changed is L2 / L1 ≦ 9, with the distance to the position being 1.5 mm or more and the lateral groove protrusion after the shape change. A tire vulcanization mold characterized by   The projection peripheral length L1 of the original portion and the projection peripheral length L2 of the shape-changed portion have a relationship of L2 / L1 ≦ 2, and the area S2 of the lateral groove projection after the shape change is the original shape. 6. The tire vulcanization mold according to claim 5, wherein the mold is 70% to 120% of the area S1 of the lateral groove protrusion.   The mold for tire vulcanization according to claim 6, wherein an area S2 of the lateral groove protrusion after the shape change is 95% to 105% of an area S1 of the original lateral groove protrusion.   A pneumatic tire vulcanized using the tire vulcanization mold according to claim 1.