JP4591092B2 - Pneumatic tire and tire mold - Google Patents

Description

  The present invention relates to a pneumatic tire and a tire molding die, and more particularly, a pneumatic tire capable of suppressing uneven wear caused by molding marks on a tread surface generated at a division position of the tire molding die, and the tire molding thereof. Regarding molds.

  In a pneumatic tire that is vulcanized and molded by a split mold type tire molding die, the rubber material in the tread portion is sandwiched between the tire molding die at the divided position, and molding marks such as burrs are generated on the tread surface. . When such a molding trace is on the tread surface, uneven wear occurs along the molding trace when the vehicle is fully opened when the tire is new. When such uneven wear grows through continuous use of the tire, obstacles such as a decrease in tire life, a decrease in gripping force, and a deterioration in handling performance occur (the tire performance decreases).

  In this regard, the technology described in Patent Document 1 is known for conventional pneumatic tires. A conventional pneumatic tire has at least one continuous circumferential rib in a tread portion, and the tread portion is vulcanized by an intermediate mold of a vulcanization mold divided into a plurality of circumferential directions. It is a pneumatic tire for high-speed traveling, and a recess is provided on the surface of the circumferential rib in the vicinity of the position that matches the dividing surface of the intermediate mold so as to reduce the temperature in the contact area of the recess during high-speed traveling. It is characterized by that.

Japanese Patent Laid-Open No. 4-8607

  It is an object of the present invention to provide a pneumatic tire capable of suppressing uneven wear caused by molding marks on a tread surface generated at a division position of a tire molding die, and a tire molding die thereof.

In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire applied to a slick tire or an intermediate tire while being vulcanized and molded using a split-type tire molding die, A division position s of the tire molding die extends in the tire circumferential direction on the tread surface, and a recess extending in the tire circumferential direction along the division position s of the tire molding die is formed on the tread surface. The inner surface of the concave portion can be grounded when the tire contacts the ground, and the concave portion meanders in the tire circumferential direction in a plan view of the tread portion, and a boundary portion between the concave portion and the profile surface of the tread portion is It is formed smoothly .

In this pneumatic tire, since the concave portion is formed on the tread surface along the division position s of the tire molding die, the ground pressure in the concave portion is reduced from the surroundings when the tire is used. Then, since uneven wear of the tread portion due to the molding marks is suppressed at the initial use of the tire, the tire surface is uniformly worn from the beginning of a new article. Thereby, there exists an advantage which various performances of a tire improve.
In this pneumatic tire, the concave portion is configured to meander in the tire circumferential direction (having amplitude in the tire width direction) in a plan view of the tread portion, so the concave portion is linearly formed in the tire circumferential direction. Compared with the structure currently performed, the secondary partial wear which generate | occur | produces from the edge of a recessed part is reduced effectively. Thereby, there exists an advantage by which the partial wear of a tread part is suppressed effectively.
Further, in this pneumatic tire, the boundary portion between the concave portion and the profile surface of the tread portion is formed smoothly, so that the boundary between the concave portion and the profile surface of the tread portion when the inner surface of the concave portion contacts the ground when the tire contacts the ground. The part is grounded smoothly. As a result, secondary uneven wear that occurs starting from the boundary portion (edge of the recess) between the recess and the profile surface of the tread portion is reduced, so that the uneven wear of the tread portion is effectively suppressed. is there.

  In the pneumatic tire according to the present invention, the width of the recess is in the range of 5 [mm] or more and 50 [mm] or less, and the depth of the recess is 0.1 [mm] at the deepest portion. It is in the range of 1.0 [mm] or less.

  In this pneumatic tire, since the recess (width and depth) of the recess is optimized, the inner surface of the recess is substantially grounded when the tire contacts the ground. Thereby, since the ground contact shape of the tread part at the time of tire use is suitably ensured, there is an advantage that various performances of the tire are maintained.

The pneumatic tire according to the present invention is a pneumatic tire applied to a slick tire or an intermediate tire while being vulcanized and molded using a split-type tire molding die, The division position s extends in the tire circumferential direction on the tread surface, and a recess extending in the tire circumferential direction along the division position s of the tire molding die is formed on the tread surface. An inner surface of the recess can be grounded, and a stress distribution portion is formed in the recess to disperse stress generated in the recess when the tire rolls, and the profile surface of the recess and the tread portion The boundary portion is formed smoothly.

  In this pneumatic tire, since the stress dispersion part that disperses the stress generated in the recess when the tire rolls is formed in the recess, the stress generated in the recess when the tire rolls is dispersed by the stress dispersion part. . Thereby, there is an advantage that the concentrated stress in the recess is relaxed and the uneven wear of the tire is effectively suppressed.

  In the pneumatic tire according to the present invention, the stress dispersion portion intersects the division position s of the tire molding die in a plan view of the tread portion.

  In this pneumatic tire, in the plan view of the tread portion, the stress dispersion portion is formed so as to intersect the division position s of the tire molding die, so that the concentrated stress in the recess is further relaxed, There is an advantage that uneven wear of the tire is more effectively suppressed.

  In the pneumatic tire according to the present invention, the stress dispersion portion has a width of 1 [mm] or less in a plan view of the tread portion, and an unevenness with respect to the inner surface of the recess is 1 [mm] or less. Configured.

  In this pneumatic tire, the stress dispersion portion is configured so that the width of the tread portion is 1 [mm] or less and the amount of unevenness with respect to the inner surface of the recess is 1 [mm] or less. Therefore, there is an advantage that the occurrence of uneven wear starting from the stress dispersion portion is suppressed.

  In the pneumatic tire according to the present invention, an interval p between intersections of the stress dispersion portion and the division position s by the tire molding die is 40 [mm] or less.

  In this pneumatic tire, since the interval (pitch length) p between the points where the stress dispersion portion and the division position s by the tire molding die intersect in the recess is optimized, the concentrated stress in the recess is more increased. There is an advantage that the uneven wear of the tire is more effectively suppressed.

  In the pneumatic tire according to the present invention, the interval p between the intersections of the stress distribution portion and the division position s by the tire molding die is not uniform in the tire circumferential direction.

  In this pneumatic tire, since the interval p between the points where the stress distribution portion and the division position s by the tire molding die intersect in the recess is uneven (unequal pitch) in the tire circumferential direction, There is an advantage that the concentrated stress is relaxed and uneven wear of the tire is more effectively suppressed.

  The tire molding die according to the present invention is characterized in that the above pneumatic tire can be molded.

  In the pneumatic tire according to the present invention, since the recess is formed along the division position s of the tire molding die on the tread surface, the ground pressure in the recess is reduced from the surroundings when the tire is used. Then, since uneven wear of the tread portion due to the molding marks is suppressed at the initial use of the tire, the tire surface is uniformly worn from the beginning of a new article. Thereby, there exists an advantage which various performances of a tire improve.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. Moreover, the some modified example described in this Example can be arbitrarily combined within the range obvious to those skilled in the art.

  1 and 2 are an enlarged plan view (FIG. 1) and a cross-sectional view taken along line AA (FIG. 2) showing a tread portion of a pneumatic tire according to an embodiment of the present invention. 3-8 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. FIG. 9 is a table showing performance tests of pneumatic tires according to examples of the present invention.

  The pneumatic tire 1 is vulcanized and molded using a split tire molding die, for example, a tire molding die that is divided into two in the tire width direction around a tire equator line (center line of the contact surface). . For this reason, the division position s of the tire molding die extends in the tire circumferential direction along the tire equator line on the tread surface. In a conventional pneumatic tire, molding marks (divided marks) such as burrs are generated along the division position s of the tire molding die.

  On the other hand, in the pneumatic tire 1, the concave portion 2 is formed on the tread surface along the division position s of the tire molding die in a plan view of the tread portion (see FIG. 1). Specifically, the recess 2 is formed in the tire circumferential direction along the tire equator line (center line of the ground contact surface) which is the division position s of the tire molding die. In this pneumatic tire 1, the recess 2 is continuously formed over the entire circumference of the tire. However, the present invention is not limited to this, and the recess 2 may be formed discontinuously in the tire circumferential direction (illustrated). (Omitted).

  The recess 2 is configured to be recessed with respect to the tire profile line in a sectional view in the tire meridian direction (see FIG. 2). Further, the recess 2 is defined to have a recess (width and depth) so that the inner surface thereof is substantially grounded when the tire is in contact with the tire. Specifically, the width of the recess 2 is in the range of 5 [mm] to 50 [mm], and the depth of the recess 2 is 0.1 [mm] to 1.0 [mm at the deepest portion. ] The recessed part 2 is comprised so that it may exist in the following ranges.

[Function and effect]
In general, in a pneumatic tire that is vulcanized and molded by a split-type tire molding die, a molding mark remains on the tread surface along the split position s of the tire molding die. By using the tire, uneven wear of the tread portion grows starting from this molding mark. In this respect, in the pneumatic tire 1, since the concave portion 2 is formed on the tread surface along the division position s of the tire molding die, the ground pressure in the concave portion 2 is reduced from the surroundings when the tire is used. The Then, since uneven wear of the tread portion due to the molding marks is suppressed at the initial use of the tire, the tire surface is uniformly worn from the beginning of a new article. Thereby, there exists an advantage which various performances of a tire improve.

  Moreover, in the slick tire which does not have this recessed part 2, in order to prevent the partial wear by this molding trace, the operation | work which peels off the tire surface (tread surface) by a running-in operation is needed. In this respect, the pneumatic tire 1 has an advantage that it can be fully opened from the beginning of a new tire without requiring a break-in operation because uneven wear due to molding marks is suppressed.

  Moreover, in this pneumatic tire 1, the width a of the recess 2 is in the range of 5 [mm] or more and 50 [mm] or less, and the depth b of the recess 2 is 0.1 [mm] at the deepest part. Since the recesses (width a and depth b) of the recess 2 are defined so as to be in the range of 1.0 [mm] or less, the inner surface of the recess 2 is substantially grounded when the tire is grounded. It is configured. Thereby, since the contact shape of the tread part at the time of tire use is suitably secured, there is an advantage that various performances of the tire are maintained.

  In some pneumatic tires such as bias tires, the profile of the pneumatic tire is adjusted by forming the profile of the tire molding die in a concave shape. However, in such a configuration, there is a possibility that the ground contact shape of each manufactured pneumatic tire is deteriorated or the effect of suppressing uneven wear is reduced. In this respect, the pneumatic tire 1 has an advantage that only the vicinity of the division position s of the tire molding die is formed in a concave shape with respect to the profile line, so that such a problem hardly occurs.

[Modification 1]
The pneumatic tire 1 is configured such that the recess 2 meanders in the tire circumferential direction (having amplitude in the tire width direction) in a plan view of the tread portion (see FIG. 1). In other words, the edge of the recess 2 (the boundary portion between the recess 2 and the profile line in a sectional view in the tire meridian direction) is configured to meander in the tire circumferential direction in a plan view of the tread portion. In such a configuration, secondary uneven wear generated starting from the edge of the recess 2 is effectively reduced as compared with a configuration in which the recess 2 is linearly formed in the tire circumferential direction. Thereby, there exists an advantage by which the partial wear of a tread part is suppressed effectively.

[Modification 2]
Moreover, in this pneumatic tire 1, it is preferable that the boundary part of the recessed part 2 and the profile surface of a tread part is formed smoothly (refer FIG. 2). For example, it is preferable that the recess 2 and the profile line of the tread portion are connected by an arc shape, a sine wave shape, or other discontinuous and gentle curve (curved surface) in a sectional view in the tire meridian direction. In such a configuration, when the inner surface of the concave portion 2 is grounded when the tire is grounded, the boundary portion between the concave portion 2 and the profile surface of the tread portion is smoothly grounded. As a result, secondary uneven wear that occurs starting from the boundary portion between the recess 2 and the profile surface of the tread portion (the edge of the recess 2) is reduced, so that uneven wear of the tread portion is effectively suppressed. There are advantages.

[Modification 3]
Moreover, in this pneumatic tire 1, the stress distribution part 21 which disperse | distributes the stress which arises in the recessed part 2 at the time of tire rolling is formed in the recessed part 2 (refer FIGS. 3-7). The stress dispersion portion 21 is composed of, for example, a narrow groove, a bank, a hollow portion, a convex portion, a knurled portion, and the like. In such a configuration, the stress generated in the recess 2 when the tire rolls is dispersed by the stress dispersion portion 21. Thereby, the concentrated stress in the recessed part 2 is relieved and there exists an advantage by which the partial wear of a tire is suppressed effectively. In addition, the stress dispersion | distribution part 21 may have any cross-sectional shape, such as a square cross section, a rectangular cross section, and a substantially arc-shaped cross section. Moreover, the stress dispersion | distribution part 21 may be comprised by linear form by planar view of the tread part, and may be comprised by circular shape.

  Moreover, it is preferable that the stress distribution part 21 is formed so that it may cross | intersect with the division | segmentation position s (division line extended in a tire peripheral direction) of a tire shaping die in planar view of a tread part (FIG. 3). For example, when the stress distribution portion 21 is a narrow groove or bank, the narrow groove or bank and the division position s of the tire molding die are configured to intersect each other. Further, when the stress distribution part 21 is a dent part, a convex part, a knurled part, etc., the stress distribution part group composed of a plurality of dent parts and the division position s of the tire molding die intersect. Is done. Thereby, the concentrated stress in the recessed part 2 is relieved more, and there exists an advantage by which the partial wear of a tire is suppressed more effectively.

  In addition, the stress distribution portion 21 has a width of 1 [mm] or less in plan view of the tread portion, and the amount of unevenness with respect to the inner surface of the concave portion 2 (depth of the narrow groove and concave portion, height of the convex portion and knurled portion). The amount of unevenness on the surface is 1 [mm] or less. Thereby, there exists an advantage by which generation | occurrence | production of the partial wear which started the stress dispersion | distribution part 21 is suppressed. Moreover, since the fall of the rigidity of the compound which comprises a tread part is suppressed, there exists an advantage by which operability is maintained. Note that even the minute stress dispersion portion 21 reduces the uneven wear during the initial wear of the tire, and thus has an advantage of effectively suppressing the occurrence and growth of the subsequent uneven wear. In addition, the minute stress dispersion portion 21 has an advantage that the adverse effect on the tire performance is small.

  In addition, the stress distribution part 21 is formed by applying the pattern of the stress distribution part 21 to the tire molding die by machining, casting, knurling, embossing, and the like, and transferring the pattern to the tread surface of the pneumatic tire 1. Is formed. With such a configuration, the flow change of the rubber material at the time of vulcanization molding of the tire is reduced by the pattern of the stress dispersion portion 21. Thereby, since the physical-property change of a tread rubber is reduced, there exists an advantage by which the local partial wear of a tread part is suppressed.

  The interval (pitch length) p between the points where the stress distribution portion 21 and the division position s by the tire molding die intersect in the recess 2 is preferably 40 [mm] or less, and preferably 10 [mm] or less. It is more preferable that Thereby, the concentrated stress in the recessed part 2 is relieved more, and there exists an advantage by which the partial wear of a tire is suppressed more effectively.

  Moreover, it is preferable that the space | interval p of the point where the stress distribution part 21 and the division | segmentation position s by a tire shaping die cross | intersect in the recessed part 2 is nonuniform (unequal pitch) with respect to a tire peripheral direction. Thereby, the concentrated stress in the recessed part 2 is relieved more, and there exists an advantage by which the partial wear of a tire is suppressed more effectively.

[Modification 4]
Further, since the pneumatic tire 1 is vulcanized and molded by a tire molding die that is divided into two in the tire circumferential direction, a single trace of molding is formed on the tread surface along the division position of the tire molding die. Remains. For this reason, the one recessed part 2 is formed on a tread surface (refer FIG. 1 and FIG. 2).

  On the other hand, for example, in order to adjust the width of the pneumatic tire 1, a spacer is interposed between a pair of tire molding dies, and the pneumatic tire 1 may be vulcanized in this state. In this case, since the rubber material of the tread portion is sandwiched between the tire molding die and the spacer, two molding marks are generated on the tread surface. That is, molding marks are generated at two locations between the tire molding die on the left side of the tire and the spacer and between the spacer and the tire molding die on the right side of the tire. In such a configuration, it is preferable that the recesses 2 are formed along the respective molding marks. That is, a plurality of recesses 2 may be formed on the tread surface.

[Application example]
For example, in a racing slick tire mainly used on a circuit, since the input (load) to the tread portion during use is large, uneven wear is likely to occur starting from a molding mark. In this respect, in the pneumatic tire 1, uneven wear of the tread portion due to the molding marks is effectively suppressed by the concave portion 2 formed on the tread surface. Therefore, when this pneumatic tire 1 is applied to a racing slick tire, there is an advantage that various performances of the tire are more remarkably improved.

  The pneumatic tire 1 is not limited to the slick tire as described above, and may be applied to a tire having a groove on the tread surface for ensuring drainage performance. For example, the pneumatic tire 1 may be applied to an intermediate tire used on a road surface in an intermediate state between a wet road and a dry road under a drizzle condition (see FIG. 8).

[Tire mold]
Further, the tire molding die for molding the pneumatic tire 1 can be arbitrarily configured within the range obvious to those skilled in the art (not shown). For example, in such a tire molding die, in order to form the concave portion 2 of the tread surface, a convex portion is arranged at the division position (not shown).

[Tire manufacturing process]
Moreover, the tire manufacturing process for manufacturing this pneumatic tire 1 can be arbitrarily configured within the range obvious to those skilled in the art (not shown). For example, the pneumatic tire 1 having the recess 2 is manufactured by the following tire manufacturing process. First, a green tire (raw tire) is molded by a molding machine (not shown) using each member such as a carcass material, a belt material, a tread material, and a bead material. Next, this green tire is filled in a tire vulcanization mold (not shown). Next, the vulcanization mold is heated, and the green tire is expanded radially outward by a pressure device (not shown), so that the tire vulcanization mold contacts the tread surface molding portion. Next, vulcanization is performed by heating the green tire and bonding rubber molecules and sulfur molecules in the tread portion. At this time, the shape of the tread surface molding portion of the tire vulcanization mold is transferred to the tread surface of the green tire, and the concave portion 2 of the pneumatic tire 1 is molded. Then, the molded pneumatic tire 1 is drawn out from the tire vulcanization mold.

[performance test]
In Example 1, performance tests on (1) uneven wear resistance and (2) feeling (running feeling) were performed on a plurality of pneumatic tires having different conditions (see FIG. 9). In this performance test, a pneumatic tire having a tire size of 230 / 625R17 is assembled on a regular rim specified by JATMA, and a normal load and a normal air pressure are applied to the pneumatic tire. The pneumatic tire is mounted on a 2000 cc test vehicle that is an FR vehicle. In the tire size display, each numerical value means (tread width) / (tire outer diameter) R (inch), and the symbol R means a radial tire.

  In this performance test, the test vehicle makes five laps on a test course of 2 [km] per turn, and the same driver evaluates the uneven wear resistance and feeling of the pneumatic tire for each run. Evaluation is performed with a maximum of 5 points, and the larger the value, the better. In addition, the average time taken for the test run is measured.

  In this performance test, the conventional example shows a pneumatic tire having no recess. On the other hand, Invention Examples 1 to 4 show a pneumatic tire 1 having a recess 2 at a division position of a tire molding die (see FIGS. 1 to 4). Inventive Example 3 and Inventive Example 4 is a pneumatic tire 1 in which concave and convex portions (thin grooves) 21 are formed in the concave portion 2 (see FIGS. 3 and 4).

  First, comparing the inventive examples 1 to 4 and the conventional example, it can be seen that the pneumatic tire 1 of the inventive examples 1 to 4 has improved uneven wear resistance and feeling. Further, when Invention Example 1 and Invention Example 2 are compared, when the recess 2 is too deep, the grip feeling decreases because the contact pressure is small. Moreover, uneven wear resistance also decreases.

  Next, when Invention Example 1 and Invention Example 3 are compared, it can be seen that the formation of the stress dispersion portion 21 in the recess 2 improves both the uneven wear resistance and the feeling. On the other hand, when the unevenness | corrugation amount (depth of a fine groove) of the stress dispersion | distribution part 21 is too large, it turns out that the effect of a snake deteriorates, a feeling falls, and uneven wear resistance falls.

  As described above, the pneumatic tire and the tire molding die according to the present invention are useful in that it is possible to suppress uneven wear caused by molding marks on the tread surface generated at the division position of the tire molding die.

1 is an enlarged plan view showing a tread portion of a pneumatic tire according to an embodiment of the present invention. It is AA sectional view taken on the line of FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is a graph which shows the performance test result of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Concave part 21 Stress distribution part s Dividing position

Claims (8)

A pneumatic tire that is vulcanized and molded using a split-type tire molding die and is applied to a slick tire or an intermediate tire ,
A division position s of the tire molding die extends in the tire circumferential direction on the tread surface, and a recess extending in the tire circumferential direction along the division position s of the tire molding die is formed on the tread surface. ,
The inner surface of the recess can be grounded when the tire is grounded, and
A pneumatic tire characterized in that the concave portion meanders in the tire circumferential direction in a plan view of the tread portion, and a boundary portion between the concave portion and the profile surface of the tread portion is smoothly formed . A pneumatic tire that is vulcanized and molded using a split-type tire molding die and is applied to a slick tire or an intermediate tire ,
A division position s of the tire molding die extends in the tire circumferential direction on the tread surface, and a recess extending in the tire circumferential direction along the division position s of the tire molding die is formed on the tread surface. ,
The inner surface of the recess can be grounded when the tire is grounded, and
A stress dispersion part for dispersing stress generated in the recess during rolling of the tire is formed in the recess, and a boundary part between the recess and the profile surface of the tread part is smoothly formed. Pneumatic tires. The pneumatic tire according to claim 2 , wherein the stress dispersion portion intersects with a division position s of the tire molding die in a plan view of the tread portion. Stress dispersion portion in the plan view of the tread portion, the width is not less 1 [mm] or less, according to claim 2 or 3 configured irregularity with respect to the inner surface of the concave portion is 1 [mm] or less Pneumatic tires. The pneumatic tire according to any one of claims 2 to 4 , wherein an interval p between intersections of the stress dispersion portion and the division position s by the tire molding die is 40 [mm] or less. The pneumatic tire according to any one of claims 2 to 5 , wherein a distance p between intersections between the stress dispersion portion and the division position s by the tire molding die is not uniform in the tire circumferential direction. The width of the recess is in the range of 5 [mm] or more and 50 [mm] or less, and the depth of the recess is in the range of 0.1 [mm] or more and 1.0 [mm] or less at the deepest portion. The pneumatic tire according to any one of claims 1 to 6 . A tire molding die, wherein the pneumatic tire according to any one of claims 1 to 7 can be molded.

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