JP2016107935A - Pneumatic tire and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of suppressing poor appearance of a side wall part and blown rubber without causing an increase in mass.SOLUTION: A pneumatic tire 1 includes a convex pattern 3 projecting outside a side wall part 2 on a part of the side wall part 2 on its periphery. A side wall rubber 21 constituting the outside surface of the side wall part 2 includes an overlapped part 22 overlapped in a thickness direction in a part of a tire circumferential direction. A part of the convex pattern 3 is positioned at the overlapped part 22 of the side wall rubber 21.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire suitable for a small passenger car such as a light vehicle and a method for manufacturing the same.

  In recent years, various pneumatic tires that have improved fuel efficiency by weight reduction have been proposed. Such a low fuel consumption tire can provide a vehicle with excellent fuel efficiency by being mounted on a small passenger car.

  By the way, various markings are given to the sidewall portion of the pneumatic tire. For example, a convex pattern that protrudes outside the sidewall portion is provided on a part of the periphery of the sidewall portion. Such a convex pattern is effective for improving the visibility.

  However, in the pneumatic tire having the convex pattern described above, local volume of the sidewall rubber is insufficient in the convex pattern and its surroundings, resulting in poor appearance in the sidewall part, and the side wall rubber and carcass. There was a possibility that a so-called bron rubber may be generated in which an air pocket (edema-like interfacial adhesion peeling) occurs between the ply and the ply.

  Local volume shortage of the sidewall rubber can be suppressed by increasing the thickness of the entire sidewall rubber. However, when sidewall rubber having a large thickness is used for a pneumatic tire, the mass of the tire increases and the fuel consumption performance deteriorates. Therefore, in particular, in the above-described pneumatic tire for small passenger cars, it is difficult to apply the sidewall rubber having a large thickness in order to eliminate the local volume shortage of the sidewall rubber.

  On the other hand, as a countermeasure against the above-mentioned Bron rubber, Patent Document 1 below proposes a side wall rubber sticking device in which a conical protrusion is provided on a guide roller that presses a side wall rubber.

JP 2013-71433 A

  However, even if the sticking device described in Patent Document 1 is used, it is difficult to eliminate the local volume shortage of the sidewall rubber in the convex pattern and its surroundings, and further improvement has been demanded. .

  The present invention has been devised in view of the above-described actual situation, and a main object thereof is to provide a pneumatic tire that can suppress an appearance defect of a sidewall portion and a bron rubber without causing an increase in mass.

  A first aspect of the present invention is a pneumatic tire provided with a convex pattern protruding on the outside of the sidewall portion on a part of the circumference of the sidewall portion, and forms an outer surface of the sidewall portion. Side wall rubber has an overlapping portion that is overlapped in the thickness direction at a portion in the tire circumferential direction, and a portion of the convex pattern is located on the overlapping portion of the sidewall rubber. Features.

  In the pneumatic tire according to the present invention, it is desirable that the center of the convex pattern in the tire circumferential direction is located on the overlapping portion.

  In the pneumatic tire according to the present invention, it is desirable that a thickness of the sidewall rubber at a tire maximum width position is 3.0 mm or less.

In the pneumatic tire according to the present invention, the convex pattern preferably has a volume of 200 to 1500 mm ³ .

    In the pneumatic tire according to the present invention, it is preferable that a circumferential length of the overlapping portion is smaller than a circumferential length of the convex pattern.

  2nd invention of this invention is a manufacturing method of the pneumatic tire which provided the convex-shaped pattern which protrudes on the outer side of the said sidewall part in a part on the periphery of a sidewall part, Comprising: Unvulcanized tire structure A molding step for forming green tires by sequentially pasting members; and a vulcanization step for vulcanizing and molding the raw tires into a vulcanization mold, wherein the molding step is performed outside the sidewall portion. Including a superposition step of superposing side wall rubber forming a side surface in a thickness direction in a part of the circumferential direction of the raw tire to form a superposition part, and the vulcanization mold is formed on the side wall part, A concave portion for forming a convex pattern, and the vulcanization step includes a step of aligning the overlapping portion of the green tire with the concave portion of the vulcanization mold, and a convex pattern by the concave portion. Including a molding step. To.

  In the method for manufacturing a pneumatic tire according to the present invention, the molding step includes a step of winding the sidewall rubber around a rotating former, and the overlapping step includes a winding start end and a winding end of the sidewall rubber. It is desirable to include a step of overlapping and joining the end in the circumferential direction of the green tire.

  In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that the overlapping portion is overlapped with a length of 4 to 8 mm in a circumferential direction of the former.

  The pneumatic tire of the present invention includes a convex pattern that protrudes outside the sidewall portion on a part of the circumference of the sidewall portion. Such a convex pattern has good visibility.

  The sidewall portion has an overlapping portion in which the sidewall rubber forming the outer surface thereof is overlapped in the thickness direction at a part in the tire circumferential direction. Such an overlapping portion has a larger volume of sidewall rubber than other regions. And a part of convex pattern is located on the overlapping part of sidewall rubber. As a result, the sidewall rubber at the overlapping portion compensates for the convex pattern and local volume shortage in the vicinity thereof. Therefore, according to the pneumatic tire of the present invention, it is possible to suppress the appearance defect of the sidewall portion and the Bron rubber without increasing the tire mass.

  The production method of the present invention is a method for producing a pneumatic tire having a convex pattern protruding on the outer side of a sidewall portion on a part of the circumference of the sidewall portion, and an unvulcanized tire constituent member Are sequentially pasted to form a green tire, and a vulcanization process is performed in which the green tire is put into a vulcanization mold and vulcanized. The vulcanization mold has a concave portion for forming a convex pattern in the sidewall portion.

  The forming step includes an overlapping step in which an overlapping portion is formed by overlapping the sidewall rubber forming the outer surface of the sidewall portion in the thickness direction in a part of the circumferential direction of the raw tire. The overlapping portion formed here has a larger volume of sidewall rubber than other regions.

  The vulcanization step includes a step of aligning the overlapping portion of the green tire with the concave portion of the vulcanization mold and a step of forming a convex pattern by the concave portion. Thereby, the sidewall rubber of the overlapping portion moves to the concave portion to compensate for the local volume deficiency in the convex pattern and its periphery. Therefore, according to the manufacturing method of the present invention, it is possible to suppress the appearance defect of the sidewall portion and the Bron rubber without increasing the tire mass.

It is a perspective view showing one embodiment of the pneumatic tire of the present invention. It is a perspective view which shows the shaping | molding process which shape | molds the pneumatic tire of FIG. It is a perspective view which shows the superimposition process which is a part of shaping | molding process of FIG. It is a perspective view of the green tire shape | molded by the formation process of FIG. It is AA sectional drawing of the green tire of FIG. It is sectional drawing which shows the vulcanization | cure process which vulcanize-molds the green tire of FIG. It is a perspective view which shows the modification of the raw tire of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a pneumatic tire 1 of the present embodiment. As shown in FIG. 1, the pneumatic tire 1 of the present embodiment includes a convex pattern 3 on a part of the circumference of the sidewall portion 2.

  The convex pattern 3 is formed to protrude outside the sidewall portion 2. The convex pattern 3 is locally and continuously formed on a part of the periphery of the sidewall portion 2. Various markings can be formed on the top 31 of the convex pattern 3. For example, in the case of the pneumatic tire 1 having an asymmetric tread pattern in which the mounting direction to the vehicle is specified, the visibility is improved if the mounting direction is displayed on the top 31 of the convex pattern 3. It is done.

  In FIG. 1, the letters “OUTSIDE”, which means that one side wall portion 2 </ b> A is mounted so as to face the outside of the vehicle, are formed on the top portion 31 of the convex pattern 3. Such characters are formed in a convex shape or a concave shape from the top portion 31. The other side wall portion 2B is formed with the letters “INSIDE” on the top 31 of the convex pattern 3 which means that the side wall portion 2B is mounted so as to face the inside of the vehicle (see FIG. Not shown). Such a convex pattern 3 has good visibility and effectively prevents erroneous mounting on the vehicle.

  The marking formed on the top 31 of the convex pattern 3 is not limited to characters, and may be a graphic or pattern mark. Further, the convex pattern 3 itself may be in a form constituting part or all of the marking.

  The outer side surface of the sidewall portion 2 is constituted by a sidewall rubber 21. The sidewall portion 2 has an overlapping portion 22 in which the sidewall rubber 21 is overlapped in the thickness direction at a part in the tire circumferential direction. Such an overlapping portion 22 has a thick portion 23 in which the volume of the sidewall rubber 21 is larger than in other regions.

  In the present embodiment, the overlapping portion 22 is formed along the tire radial direction. The direction in which the overlapping portion 22 is formed is arbitrary. For example, the overlapping portion 22 may be formed along the tire circumferential direction. The length of the overlapping portion 22 in the tire circumferential direction is smaller than the length of the convex pattern 3 in the tire circumferential direction. The length of the overlapping portion 22 in the tire radial direction is larger than the length of the convex pattern 3 in the tire radial direction.

  A part of the convex pattern 3 is located on the overlapping portion 22 of the sidewall rubber 21. Thereby, the sidewall rubber 21 of the overlapping portion 22 compensates for the local volume deficiency in the convex pattern 3 and the periphery thereof, and causes the appearance defect and the Bron rubber of the sidewall portion 2 without increasing the tire mass. It becomes possible to suppress. Therefore, according to the pneumatic tire 1, it is possible to easily manufacture a “low fuel consumption tire” that conforms to the “labeling system” by JATMA.

  The center 32 in the tire circumferential direction of the convex pattern 3 is desirably located on the overlapping portion 22. Thereby, the side wall rubber 21 of the overlapping portion 22 easily spreads uniformly on both sides of the center 32 of the convex pattern 3, and it becomes possible to further suppress the appearance defect and the Bron rubber of the side wall portion 2.

  In the pneumatic tire 1 of the present embodiment, the thickness T of the sidewall rubber 21 at the tire maximum width position is desirably 3.0 mm or less. The pneumatic tire 1 configured with such a thin sidewall rubber 21 has a small mass and contributes to an improvement in fuel efficiency.

  Generally, when the convex pattern 3 is formed on the pneumatic tire 1 having a very thin sidewall rubber 21 as in a “low fuel consumption tire”, a local volume shortage occurs in the convex pattern 3 and its periphery. There is a fear. However, in the present embodiment, the sidewall rubber 21 of the overlapping portion 22 compensates for the local volume deficiency in the convex pattern 3 and the periphery thereof, so that the appearance defect and the Bron rubber of the sidewall portion 2 are effectively suppressed. It becomes possible to do.

The volume of one independent convex pattern ³ is preferably 200 to 1500 mm ³ . When the volume of the convex pattern 3 is less than 200 mm ^3, visibility by convex pattern 3 it may not be sufficiently increased. Further, the area of the top portion 31 of the convex pattern 3 is insufficient, and the number of characters formed on the top portion 31 may be limited. Further, the rubber volume of the overlapping portion 22 becomes relatively excessive, and there is a possibility that appearance defects such as bulges may occur.

On the other hand, when the volume of the convex pattern 3 exceeds 1500 mm ³ , it may be difficult to compensate for the local volume shortage in the convex pattern 3 and its surroundings by the sidewall rubber 21 of the overlapping portion 22. .

  Hereinafter, a method for manufacturing the pneumatic tire 1 (hereinafter, simply referred to as a manufacturing method) will be described. The manufacturing method includes a molding process for molding a green tire and a vulcanization process for vulcanizing and molding the green tire.

  2 and 3 show the molding process in time series. 4 and 5 show the green tire formed in the forming process. In the molding step, the unvulcanized tire constituent members are sequentially pasted to form the raw tire 4.

  The unvulcanized tire component includes the sidewall rubber 5 and the like. As shown in FIGS. 2 and 3, the side wall rubber 5 extruded in a band shape is wound around a rotating former 6 and formed into a cylindrical shape.

  The molding process includes an overlapping process in which the sidewall rubber 5 of the raw tire 4 is overlapped to form an overlapping portion 52 (see FIG. 4).

  FIG. 3 shows the superposition process among the molding processes. In the superimposing step, the overlapping portion 52 is formed by superimposing the sidewall rubber 5 in the thickness direction on a part of the raw tire 4 in the circumferential direction.

  In the present embodiment, the winding start end 5s and the winding end end 5e of the sidewall rubber 5 are jointed by being overlapped (overlapped) in the circumferential direction of the former 6, that is, the circumferential direction of the raw tire 4. Part 52 is formed. As shown in FIGS. 4 and 5, in the overlapping portion 52, the sidewall rubber 5 is overlapped in the thickness direction, so that the overlapping portion 52 has a volume of the sidewall rubber 5 as compared with other regions. Has a thick portion 53 having a large thickness. The length of the overlapping portion 52 in the tire circumferential direction is smaller than the length of the convex pattern 3 in the tire circumferential direction. The length of the overlapping portion 52 in the tire radial direction is larger than the length of the convex pattern 3 in the tire radial direction.

  FIG. 6 shows a raw tire 4 and a vulcanization mold for vulcanizing the raw tire 4. In the drawing, a cross section including the overlapping portion 52 is shown. The vulcanization mold 7 has a recess 72 in a side ring 71 for molding the sidewall portion 2 of the pneumatic tire 1.

  The concave portion 72 is formed to be recessed outward from the inner surface of the side ring 71, and the convex pattern 3 is formed on the sidewall portion 2 of the pneumatic tire 1.

  In the vulcanization process, the overlapping pattern 52 of the green tire 4 is aligned with the concave portion 72 of the vulcanization mold 7, and the convex pattern 3 is formed on the sidewall portion 2 of the pneumatic tire 1 by the concave portion 72. A vulcanization molding process.

  In the alignment step, as shown in FIG. 6, the raw tire 4 is rotated so that the overlapping portion 52 is located at a part of the recess 72, and the circumferential phase between the overlapping portion 52 and the recess 72 is changed. The raw tires 4 are put into a vulcanizing mold 7.

  In the vulcanization molding step, the vulcanization mold 7 is closed, and the bladder 73 is expanded from the inner surface of the raw tire 4 so that the raw tire 4 is vulcanized. At this time, the sidewall rubber 5 of the overlapping portion 52 moves to the concave portion 72 of the vulcanization mold 7, and the convex pattern 3 is formed on the sidewall portion 2 of the pneumatic tire 1. Since the volume of the sidewall rubber 5 is larger in the overlapping portion 52 than in other regions, the local volume shortage in the recess 72 and its periphery is compensated.

  In the present embodiment, the overlapping portion 52 is formed by overlapping and winding the winding start end 5s and the winding end end 5e of the sidewall rubber 5 in the circumferential direction of the raw tire 4, so that the conventional molding process and Even if it compares, it is not necessary to add a new process substantially. Accordingly, it is possible to suppress the appearance defect of the sidewall portion 2 and the Bron rubber without reducing the production efficiency of the raw tire 4.

  In the positioning step, the raw tire 4 is preferably aligned so that the overlapping portion 52 is positioned at the center in the circumferential direction of the recess 72. Thereby, the side wall rubber 5 of the overlapping portion 52 is easily spread evenly on both sides of the center of the recess 72, and the local volume shortage in the recess 72 and its periphery is more effectively compensated.

  As shown in FIG. 4, the overlapping length L of the overlapping portion 52 in the circumferential direction of the former 6 is desirably 4 to 8 mm. When the overlapping length L is less than 4 mm, there is a possibility that the local volume shortage of the sidewall rubber 5 cannot be sufficiently compensated. On the other hand, when the overlapping length L exceeds 8 mm, a convex bulge called a bulge is generated in the sidewall portion 2 of the pneumatic tire 1 and the appearance may be impaired. In addition, the uniformity of the pneumatic tire 1 may be affected.

  FIG. 7 shows a modification of the green tire molded in the molding process of the present invention. The raw tire 4 </ b> A has an overlapping portion 52 </ b> A formed along the circumferential direction of the sidewall rubber 5. The overlapping portion 52 </ b> A is formed by sticking a strip-shaped sticking piece 5 </ b> B on the outside in the thickness direction of the main body portion 5 </ b> A of the sidewall rubber 5. The width, length and thickness of the sticking piece 5B can be appropriately determined according to the width, length and depth of the recess 72 of the vulcanization mold 7.

  The raw tire 4A thus formed is transferred to a vulcanization process. That is, the overlapping portion 52A of the raw tire 4A is aligned with the concave portion 72 of the vulcanization mold 7 in the alignment step, and the convex pattern 3 is formed by the concave portion 72 in the vulcanization molding step.

  The shape of the sticking piece 5B is not limited to a belt shape. For example, it can be changed as appropriate according to the shape of the recess 72 of the vulcanization mold 7. In the raw tire 4A, the overlapping portion 52A having a shape corresponding to the shape of the concave portion 72 of the vulcanization mold 7 is formed along the circumferential direction of the sidewall rubber 5, so that the local volume of the sidewall rubber 5 is insufficient. Can be effectively suppressed, and the appearance defect of the sidewall portion and the Bron rubber can be further suppressed.

  The raw tire 4A can also be applied to a so-called strip wind method in which a jointless sidewall rubber 5 is formed by spirally winding a tape-shaped rubber strip around the former 6 or the like. In this case, the former 6 may have a core-like shape in addition to the cylindrical shape shown in FIG.

  As mentioned above, although the pneumatic tire of this invention and its manufacturing method were demonstrated in detail, this invention is changed and implemented in various aspects, without being limited to said specific embodiment.

30 pneumatic tires (size 155 / 65R14) having the basic structure shown in FIG. 1 were manufactured on the basis of the specifications shown in Table 1, and the appearance defect of the side wall rubber and the occurrence rate of Bron rubber were compared.
The test method is as follows.

<Poor appearance>
Generation | occurrence | production of the bulge or the dent (concave depression) in the sidewall part of each test tire was observed visually. In Table 1, the evaluation “A” indicates that the incidence is less than 5%, the evaluation “B” indicates that the incidence is 5% or more and less than 15%, and the evaluation “C” indicates that the incidence is 15% or more. Yes.

<Bron Rubber>
Generation | occurrence | production of the Bron rubber in the sidewall part of each test tire was observed visually. In Table 1, the evaluation “A” indicates that the incidence is less than 5%, the evaluation “B” indicates that the incidence is 5% or more and less than 15%, and the evaluation “C” indicates that the incidence is 15% or more. Yes.

  As can be seen from Table 1, it was confirmed that the pneumatic tires of the examples had the appearance defects and the occurrence of Bron rubber were significantly reduced as compared with the comparative examples.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Side wall part 3 Convex pattern 4 Raw tire 5 Side wall rubber 5s Winding end 5e End of winding 6 Former 7 Vulcanization mold 21 Side wall rubber 22 Overlapping part 31 Top part 52 Overlapping part 72 Recessed part

Claims (8)

A pneumatic tire provided with a convex pattern protruding on the outside of the sidewall portion on a part of the periphery of the sidewall portion,
The sidewall rubber forming the outer surface of the sidewall portion has an overlapping portion that is overlapped in the thickness direction in a part of the tire circumferential direction,
A part of said convex pattern is located on the overlapping part of said sidewall rubber, The pneumatic tire characterized by the above-mentioned.   The pneumatic tire according to claim 1, wherein a center of the convex pattern in the tire circumferential direction is located on the overlapping portion.   The pneumatic tire according to claim 1 or 2, wherein a thickness of the sidewall rubber at a tire maximum width position is 3.0 mm or less. The pneumatic tire according to any one of claims 1 to ³ , wherein a volume of the convex pattern is 200 to 1500 mm ³ .   The pneumatic tire according to claim 1, wherein a circumferential length of the overlapping portion is smaller than a circumferential length of the convex pattern. In a part of the periphery of the sidewall part, a manufacturing method of a pneumatic tire provided with a convex pattern protruding outside the sidewall part,
A molding process of sequentially pasting unvulcanized tire components and molding a raw tire,
A vulcanization step of vulcanizing and molding the raw tire into a vulcanization mold,
The molding step includes an overlapping step of forming an overlapping portion by overlapping a sidewall rubber forming an outer surface of the sidewall portion in a thickness direction in a part of a circumferential direction of the raw tire,
The vulcanization mold has a concave portion for forming the convex pattern in the sidewall portion,
The vulcanization step includes a step of aligning the overlapping portion of the green tire with the concave portion of the vulcanization mold, and a step of forming a convex pattern by the concave portion. Tire manufacturing method. The molding step includes a step of winding the sidewall rubber around a rotating former,
The method for manufacturing a pneumatic tire according to claim 6, wherein the overlapping step includes a step of overlapping and joining the winding start end and winding end of the sidewall rubber in the circumferential direction of the green tire. The method for manufacturing a pneumatic tire according to claim 7, wherein the overlapping portion is overlapped with a length of 4 to 8 mm in a circumferential direction of the former.

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