JP2013060181A - Pneumatic tire and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that effectively prevents air from stagnating in a sidewall part in a vulcanization process by adding a projection body to reduce vulcanization failure, and utilizes the projection body as an ornament, and a manufacturing method for the same.SOLUTION: The pneumatic tire T is provided with: a tread part 1 extending in a circumferential direction of a tire to make a ring shape; a pair of sidewall parts 2 arranged on both sides of the tread part 1; a pair of bead parts 3 arranged on the inside of a radial direction of the tire of the sidewall parts 2; and a plurality of band-like projection parts 9a projecting from the surfaces of the sidewall parts 2 and coupled to cross each other, on the outer face of at least one of the sidewall parts 2. The pneumatic tire includes a plurality of projection bodies 9 formed by gradually reducing the height of each band-like projection part 9 toward a terminal side and arranged at different positions on the circumference of the tire.

Description

  The present invention relates to a pneumatic tire provided with protrusions on the outer surface of a sidewall portion and a method for manufacturing the same, and more specifically, by effectively adding air to the sidewall portion in the vulcanization process by adding protrusions. The present invention relates to a pneumatic tire that can reduce vulcanization failure and can use the protrusion as a decoration, and a method for manufacturing the same.

  When manufacturing a pneumatic tire, after molding an unvulcanized pneumatic tire, the unvulcanized pneumatic tire is vulcanized in a mold. In such a vulcanization process, an air pool may be formed in the sidewall portion, resulting in a vulcanization failure. Therefore, in order to form a belt-like protrusion that extends in the tire circumferential direction or the tire width direction on the outer surface of the sidewall portion of the pneumatic tire, in other words, to form the protrusion on the portion corresponding to the sidewall portion of the mold It has been proposed to collect and exhaust the air remaining between the sidewall portion and the mold through the recess (for example, see Patent Document 1).

  However, when a belt-like protrusion that extends only in the tire circumferential direction or the tire width direction is provided on the outer surface of the sidewall portion of the pneumatic tire, it is possible to effectively suppress air accumulation in the sidewall portion in the vulcanization process. Therefore, the effect of reducing the vulcanization failure is insufficient. In addition, since the belt-like projections extending in the tire circumferential direction or the tire width direction have a low decorative property, there is also a drawback that the appearance of the sidewall portion is deteriorated.

JP 2008-1353 A

  The object of the present invention is to effectively suppress the accumulation of air in the sidewall portion in the vulcanization process by adding a protrusion, thereby reducing vulcanization failure and making it possible to use the protrusion as a decoration. It is in providing a pneumatic tire and its manufacturing method.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a tread portion that extends in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. In a pneumatic tire having a pair of bead portions arranged on the inner side in the tire radial direction, a plurality of tires coupled to the outer surface of at least one sidewall portion so as to protrude from the surface of the sidewall portion and intersect each other A plurality of protrusions formed by gradually reducing the height of each band-like protrusion toward the end side, and these protrusions are arranged at different positions on the tire circumference. To do.

  On the other hand, the manufacturing method of the pneumatic tire of the present invention for achieving the above object includes a tread portion extending in the tire circumferential direction to form an annular shape, and a pair of sidewall portions disposed on both sides of the tread portion. And a cavity for molding a pneumatic tire having a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions, and the surface of the sidewall portions on the outer surface of at least one sidewall portion. A plurality of belt-like projections that protrude from each other and are coupled so as to intersect with each other, and each of the belt-like projections has a recess for forming a plurality of projections that are gradually reduced toward the distal end. In addition, a mold in which these concave portions are arranged at different positions on the tire circumference is used, and an unvulcanized pneumatic tire is vulcanized in the mold.

  In the present invention, a plurality of protrusions are provided on the outer surface of at least one sidewall portion, that is, by providing a recess for forming the protrusion in a portion corresponding to the sidewall portion of the mold, the recess is formed. Since the air passage during vulcanization is used, it is possible to suppress the accumulation of air formed between the sidewall portion and the mold. In particular, the above-described protrusion includes a plurality of band-shaped protrusions that protrude from the surface of the sidewall portion and are coupled so as to cross each other, and the height of each band-shaped protrusion is gradually reduced toward the end side. Since it has a structure, it is possible to effectively collect a larger area of residual air. Therefore, it is possible to effectively suppress air accumulation in the sidewall portion in the vulcanization process and reduce vulcanization failure. Moreover, the said protrusion can be utilized as a simple decoration body by the combination of a several strip | belt-shaped protrusion part. Therefore, the protrusion for collecting air does not deteriorate the appearance of the sidewall portion, but rather contributes to the improvement of the appearance.

  In the present invention, it is preferable that the height from the surface of the side wall portion of the belt-like projection is the maximum value at the intersection of the belt-like projection, and a mold vent hole is disposed at the intersection of the belt-like projection. Thereby, the air remaining between the sidewall portion and the mold can be exhausted more effectively.

  It is preferable that the maximum value of the height from the surface of the sidewall portion of the belt-like projection is 0.3 mm to 2.0 mm, and the width of the belt-like projection is 0.3 mm to 2.0 mm. Thereby, the suppression effect of an air pool can fully be exhibited, and also the visibility as a decoration body of a projection body can fully be ensured.

  Various shapes can be adopted as the shape of the belt-like protrusion. In particular, it is preferable that the shape of the cross section of the belt-like protrusion is such that it is wider on the base side than on the top side. Moreover, it is preferable to comprise the outline of the cross section of a strip | belt-shaped projection part with the curve or straight line which does not contain a bending point. Thereby, since the rubber flow to the concave portion for forming the protrusion is improved, the effect of suppressing air accumulation can be enhanced.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is a side view which shows the pneumatic tire of FIG. It is a side view which expands and shows the principal part of the sidewall part of the pneumatic tire of FIG. It is a perspective view which shows the protrusion formed in the outer surface of the sidewall part of the pneumatic tire of FIG. It is a perspective view which shows the modification of a protrusion. It is a perspective view which shows the other modification of a protrusion. It is sectional drawing which shows an example of the tire vulcanizer used with the manufacturing method of the pneumatic tire of this invention. It is sectional drawing which shows the principal part of the tire vulcanizer of FIG. The various cross-sectional shapes of a protrusion are shown, (a)-(d) is sectional drawing of a protrusion, respectively.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a pneumatic tire according to an embodiment of the present invention, and FIGS. 3 to 6 show an essential part thereof. As shown in FIG. 1, a pneumatic tire T includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, a pair of sidewall portions 2 that are disposed on both sides of the tread portion 1, and these sidewalls. A pair of bead portions 3 are provided on the inner side in the tire radial direction of the portion 2.

  A single carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded from the inside of the tire to the outside around the bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

  On the other hand, a plurality of belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5 ° or less with respect to the tire circumferential direction is disposed on the outer peripheral side of the belt layer 7. Yes. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In addition, although the tire internal structure mentioned above shows the typical example in a pneumatic tire, it is not limited to this.

  In the pneumatic tire T, a plurality of protrusions 9 are formed at equal intervals in the tire circumferential direction on the outer surface of at least one sidewall portion 2 as shown in FIGS. As shown in FIG. 4, each protrusion 9 includes a plurality of band-shaped protrusions 9a that protrude from the surface of the sidewall portion 2 and are coupled so as to intersect with each other, and the height of each band-shaped protrusion 9a is It is comprised so that it may become small gradually toward the end side. More specifically, the height from the surface of the sidewall portion 2 of the belt-like projection 9a is the maximum value at the intersection of the belt-like projection 9a, and a mold vent hole 30 described later is disposed at the intersection of the belt-like projection 9a. Has been. The protrusions 9 are preferably formed on the sidewall portions 2 on both sides, but the protrusions 9 can be provided only on the sidewall portions 2 on one side.

  In FIG. 4, the protrusion 9 is composed of a plurality of belt-like projections 9a, and has a structure in which another belt-like projection 9a branches from the middle of one belt-like projection 9a. As shown in FIG. 5, the protrusion 9 has a structure in which one belt-like protrusion 9a is crossed by another belt-like protrusion 9a, or, as shown in FIG. It is also possible to adopt a structure in which the other two belt-like projections 9a cross the belt-like projection 9a.

  FIG. 7 shows an example of a tire vulcanizing apparatus used in the method for producing a pneumatic tire of the present invention, and FIG. 8 shows the main part thereof. As shown in FIG. 7, the tire vulcanizing apparatus includes a mold 10 for forming a pneumatic tire T. The mold 10 includes a lower side plate 11 and an upper side plate 12 for forming the sidewall portion 2 of the tire T, and a lower bead ring 13 and an upper bead ring 14 for forming the bead portion 3 of the tire T. And a plurality of sector molds 15 for molding the tread portion 1 of the tire T, and the vulcanized tire T loaded in the cavity with the rotation axis in the vertical direction is vulcanized and molded. ing. At the time of vulcanization, a rubber bladder 16 formed into a cylindrical shape is inserted inside the tire T.

  The lower end portion of the bladder 16 is sandwiched between the lower bead ring 13 and the lower clamp ring 17, and the upper end portion of the bladder 16 is between the upper clamp ring 18 and the auxiliary ring 19 configured to be movable in the vertical direction. It is sandwiched between. Therefore, when the mold is closed, the upper clamp ring 18 is disposed at a lower position as shown in the figure, thereby allowing the bladder 16 to expand. On the other hand, when the mold is opened, the upper clamp ring 18 is moved to the upper position so that the tire T The bladder 16 is pulled out from the inside.

  The tire vulcanizing apparatus is provided with a pressure medium supply means (not shown) for introducing a pressure medium into the bladder 16. The tire T is vulcanized at the time of vulcanization based on the pressure of the pressure medium. The inner surface of the mold 10 is pressed from the inside. As the pressurizing medium, for example, an inert gas such as nitrogen gas or steam can be used.

  On the other hand, a heat source 21 is disposed outside the lower side plate 11, the upper side plate 12 and the sector mold 15. The structure of these heat sources 21 is not particularly limited. For example, a structure in which a cavity is provided inside and a heating medium such as steam is introduced into the cavity can be adopted.

  In the mold 10, the lower side plate 11 and the upper side plate 12 are respectively formed with recesses 29 for forming the protrusions 9 on the outer surfaces of the respective sidewall portions 2 (see FIG. 8). The recess 29 has a shape obtained by inverting the protrusion 9. That is, the concave portion 29 includes a plurality of groove portions that are recessed from the side wall molding surface and are coupled so as to intersect with each other, and each groove portion has a structure in which the depth is gradually reduced toward the end side. . Further, the depth from the side wall molding surface of the groove portion of the concave portion 29 becomes the maximum value at the intersection of the groove portion, and the vent hole 30 is disposed at the intersection of the groove portion.

  When the pneumatic tire T is vulcanized using the tire vulcanizing apparatus as described above, the unvulcanized pneumatic tire T put into the mold 10 is pressed against the inner surface of the mold 10 by the bladder 16. However, the air remaining in the vicinity of the sidewall portion 2 is collected through the concave portion 29 for forming the protrusion 9 and is discharged from the vent hole 30 to the outside of the mold 10. In particular, the protrusion 9 includes a plurality of band-shaped protrusions 9a that protrude from the surface of the sidewall portion 2 and are coupled so as to intersect with each other, and the height of each band-shaped protrusion 9a is gradually increased toward the end side. Since it has a reduced structure, it is possible to effectively collect residual air in a wider area. Further, the height of the belt-like protrusion 9a takes the maximum value at the intersection, and the vent hole 30 of the mold 10 is arranged at the intersection of the belt-like protrusion 9a. Is possible. Therefore, it is possible to effectively suppress the air accumulation in the sidewall portion 2 in the vulcanization process and reduce the vulcanization failure.

  In addition, since it is calculated | required that the residual air is collected from the wide range of a tire radial direction in the recessed part 29 for shape | molding the protrusion 9, it is desirable to ensure the length of the tire 9 in the tire radial direction enough. Therefore, the length L of the protrusion 9 in the tire radial direction is preferably set in a range of 20% to 80% of the tire cross-section height SH. If the length L of the protrusion 9 in the tire radial direction is less than 20%, the effect of suppressing air accumulation is reduced.

  Further, the protrusion 9 can be used as a simple decorative body by combining a plurality of strip-shaped protrusions 9a. For example, characters and symbols such as “Y” (FIG. 4), “X” (FIG. 5), and “*” (FIG. 6) can be easily formed. Therefore, the protrusion 9 for collecting air does not deteriorate the appearance of the sidewall portion 2, but can be used as a part of the design for improving the appearance.

  9A to 9D show various cross-sectional shapes of the protrusions. As shown in FIGS. 9A to 9D, various shapes can be adopted as the shape of the belt-like protrusion 9 a constituting the protrusion 9. In Fig.9 (a), the cross-sectional shape of the strip | belt-shaped projection part 9a is a rectangle. In FIG.9 (b), the cross-sectional shape of the strip | belt-shaped projection part 9a is a semicircle. In FIG.9 (c), the cross-sectional shape of the strip | belt-shaped projection part 9a is trapezoid. In FIG.9 (d), the cross-sectional shape of the strip | belt-shaped projection part 9a is a shape which combined the rectangle and the semicircle.

  In particular, as shown in FIGS. 9B to 9D, it is preferable that the shape of the cross section of the belt-like protrusion 9a is wider on the base side than on the top side. Further, as shown in FIGS. 9B and 9D, the outline of the cross section of the belt-like protrusion 9a may be constituted by a curve or a straight line not including a bending point. Thereby, since the rubber flow to the concave portion 29 for forming the protrusions 9 becomes good, the effect of suppressing air accumulation can be enhanced.

  It is preferable that the maximum value of the height H from the surface of the sidewall portion 2 of the band-shaped protrusion 9a is 0.3 mm to 2.0 mm, and the width W of the band-shaped protrusion 9a is 0.3 mm to 2.0 mm. Thereby, the suppression effect of an air pool can fully be exhibited, and the visibility as the decoration body of the protrusion 9 can fully be ensured. Here, if the maximum value of the height H of the belt-like protrusion 9a is smaller than 0.3 mm, the effect of suppressing air accumulation and the visibility as a decorative body are lowered, and conversely if it is larger than 2.0 mm, the protrusion 9 The rubber flow into the recess 29 for molding the resin becomes insufficient. On the other hand, if the width W of the belt-like protrusion 9a is smaller than 0.3 mm, the rubber flow into the recess 29 for forming the protrusion 9 becomes insufficient and the visibility as a decorative body is lowered. If it is larger than 2.0 mm, the effect of suppressing air accumulation is reduced.

  Using a mold having a cavity for molding a pneumatic tire having a tire size of 205 / 55R16, and having a recess for molding a plurality of protrusions on the outer surface of the sidewall portion, By vulcanizing the pneumatic tire in the mold, a plurality of protrusions were formed on the outer surface of the sidewall portion, and these protrusions were arranged at different positions on the tire circumference and Comparative Example 1 Tires 4 to 4 were produced.

  The tire of Example 1 is provided with a Y-shaped protrusion (see FIG. 4) on the outer surface of the sidewall portion, and the protrusion protrudes from the surface of the sidewall portion and is joined so as to intersect each other. And has a structure in which the height of each band-like protrusion is gradually reduced toward the end side. The maximum value of the height of the band-shaped protrusion was 2.0 mm, and the width was 1.0 mm. The angle of the belt-like protrusion with respect to the tire radial direction was 30 °.

  The tire of Example 2 is provided with an X-shaped protrusion (see FIG. 5) on the outer surface of the sidewall portion, and the protrusion protrudes from the surface of the sidewall portion and is joined so as to intersect each other. And has a structure in which the height of each band-like protrusion is gradually reduced toward the end side. The maximum value of the height of the band-shaped protrusion was 2.0 mm, and the width was 1.0 mm. The angle of the belt-like protrusion with respect to the tire radial direction was 30 °.

  The tire of Comparative Example 1 is provided with a protrusion made of a belt-like projection extending linearly in the tire radial direction on the outer surface of the sidewall portion, and the belt-like projection has a constant height over the entire length. Yes. The height of the band-shaped protrusion was 2.0 mm and the width was 1.0 mm. The angle of the belt-like protrusion with respect to the tire radial direction was 0 °.

  The tire of Comparative Example 2 is provided with a protrusion made of a belt-like projection extending linearly in the tire circumferential direction on the outer surface of the sidewall portion, and the belt-like projection has a constant height over the entire length. Yes. The height of the band-shaped protrusion was 2.0 mm and the width was 1.0 mm. The angle of the belt-like protrusions with respect to the tire radial direction was 90 °.

  The tire of Comparative Example 3 has the same structure as that of Example 1 except that the height of the belt-like protrusions constituting the protrusions is constant over the entire length.

  The tire of Comparative Example 4 has the same structure as that of Example 2 except that the height of the belt-like protrusions constituting the protrusions is constant over the entire length.

  In these Examples 1-2 and Comparative Examples 1-4, 20 protrusions were arranged at equal intervals on each sidewall portion. In particular, in Examples 1 and 2, the spacing between the protrusions in the tire circumferential direction was about 30 mm.

  For comparison, a conventional tire having the same structure as that of Example 1 was prepared except that no protrusion was provided on the sidewall portion.

  With respect to the tires of the conventional examples, Examples 1 and 2 and Comparative Examples 1 to 4 described above, the vulcanization failure occurrence rate was evaluated by the following test method, and the results are shown in Table 1.

Vulcanization failure rate:
Each of the test tires was vulcanized 40 times to check for vulcanization failure, and the vulcanization failure occurrence rate was determined. The evaluation results are shown as an index with Comparative Example 1 as 100. A smaller index value means fewer vulcanization failures.

  As is clear from Table 1, the tires of Examples 1 and 2 had a lower vulcanization failure rate than the conventional examples and Comparative Examples 1 to 4. Further, the protrusions formed on the sidewall portions of the tires of Examples 1 and 2 have a structure in which a plurality of belt-like protrusions intersect each other and the height of each belt-like protrusion changes smoothly. For this reason, the decorative body was not uncomfortable.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 9 Protrusion 9a Band-shaped projection part 10 Mold 29 Concave part 30 Vent hole T Pneumatic tire

Claims (10)

  An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radial inner side of the sidewall portions In the pneumatic tire, the outer surface of at least one of the sidewall portions includes a plurality of belt-like projections that protrude from the surface of the sidewall portion and are coupled so as to intersect with each other, and the height of each belt-like projection portion A pneumatic tire characterized in that a plurality of protrusions are formed which are gradually reduced toward the end side, and these protrusions are arranged at different positions on the tire circumference.   The height of the band-shaped protrusion from the surface of the sidewall portion is set to a maximum value at the intersection of the band-shaped protrusions, and a mold vent hole is disposed at the intersection of the band-shaped protrusions. The described pneumatic tire.   The maximum value of the height from the surface of the sidewall portion of the belt-like projection is 0.3 mm to 2.0 mm, and the width of the belt-like projection is 0.3 mm to 2.0 mm. The pneumatic tire according to 1 or 2.   The pneumatic tire according to any one of claims 1 to 3, wherein a shape of a cross section of the belt-like projection is wider on a base side than on a top side.   The pneumatic tire according to any one of claims 1 to 4, wherein a contour of a cross section of the belt-like protrusion is configured by a curve or a straight line not including a bending point.   An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radial inner side of the sidewall portions A plurality of strip-shaped protrusions that protrude from the surface of the sidewall part and are coupled to intersect with each other on the outer surface of at least one sidewall part, In addition, there are provided recesses for forming a plurality of protrusions whose height of each band-like protrusion is gradually reduced toward the end side, and a mold in which these recesses are arranged at different positions on the tire circumference is used. A method for producing a pneumatic tire, comprising vulcanizing a vulcanized pneumatic tire in the mold.   The height from the surface of the side wall portion of the belt-like projection is set to a maximum value at the intersection of the belt-like projection, and a mold vent hole is arranged at the intersection of the belt-like projection. The manufacturing method of the pneumatic tire of description.   The maximum value of the height from the surface of the sidewall portion of the belt-like projection is 0.3 mm to 2.0 mm, and the width of the belt-like projection is 0.3 mm to 2.0 mm. The manufacturing method of the pneumatic tire of 6 or 7.   The method for manufacturing a pneumatic tire according to any one of claims 6 to 8, wherein a shape of a cross section of the belt-shaped protrusion is wider on a base side than on a top side.   The method for manufacturing a pneumatic tire according to any one of claims 6 to 9, wherein a contour of a cross section of the belt-like protrusion is configured by a curve or a straight line not including a bending point.

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