JP2015128922A - pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which is largely improved in a level of the generation of a dent caused by a carcass ply compared with a conventional pneumatic tire, and has a further excellent external appearance, in the pneumatic tire having the carcass ply.SOLUTION: In a pneumatic tire having a carcass ply which is wound in a circumferential direction, the carcass ply in which a cord embedded part which is formed by coating both faces of a cord with topping rubber, and a cord non-embedded part which is formed of the topping rubber while having a thickness thinner than that of the cord embedded part are alternately arranged in a longitudinal direction at substantially-equal intervals is wound around by two rounds. The first-round cord embedded part of the wound carcass ply is fit into the second-round cord non-embedded part, and the second-round cord embedded part is fit into the first-round cord non-embedded part.

Description

  The present invention relates to a pneumatic tire having a carcass ply. More specifically, the present invention relates to a pneumatic tire having an excellent appearance with an improved generation level of dents due to an attached carcass ply.

  Generally, in a pneumatic tire, a carcass ply is wound around one turn and both ends are jointed.

  When applying an overlap joint that overlaps both ends and crimping the joint of this carcass ply, there is a difference in rigidity between the joint and other parts, and a dent in the radial direction of the side part of the product tire is generated. As a result, the appearance of the tires may be deteriorated, so the formation of dents can be suppressed by adopting a minimum joint that minimizes the amount of overlap and a zipper joint that is joined by butt instead of overlapping. (For example, patent documents 1 to 3).

Japanese Patent No. 2010-1111082 Japanese Patent No. 2005-153349 JP 2006-168420 A

  However, in recent years, the demand from the market for the appearance of product tires has become increasingly severe, and there is a need for a technology that can further suppress the formation of dents.

  Therefore, the present invention provides a pneumatic tire having a carcass ply, in which the level of dents generated by the carcass ply is drastically improved as compared with the conventional tire and has a better appearance. And

  The inventor has intensively studied and found that the above-described problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A pneumatic tire having a carcass ply wound in a circumferential direction,
Cord embedded portions formed by covering a top surface with rubber on both sides of the cord and cord non-embedded portions formed by the topping rubber so as to be thinner than the cord embedded portion are alternately arranged at substantially equal intervals in the longitudinal direction. The arranged carcass ply is wound over two laps,
The cord embedment portion of the first turn of the wound carcass ply is fitted into the cord non-buried portion of the second turn, and the cord embedment portion of the second turn is fitted into the cord non-buried portion of the first turn. It is a pneumatic tire.

The invention described in claim 2
2. The pneumatic tire according to claim 1, wherein the cord non-buried portion is formed using a carcass ply arranged at a position of a thickness center of the cord buried portion.

The invention according to claim 3
The length W of the cord burying portion is set to an interval a between cords in the cord burying portion.
W ≦ 7a
The pneumatic tire according to claim 1, wherein the pneumatic tire is in a relationship of

The invention according to claim 4
The length W of the cord burying portion is set to an interval a between cords in the cord burying portion.
3a ≦ W ≦ 5a
The pneumatic tire according to claim 3, wherein:

The invention described in claim 5
The thickness d of the cord non-buried portion is relative to the thickness D of the cord buried portion.
0.2D ≦ d ≦ 0.5D
The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is in a relationship.

  According to the present invention, in a pneumatic tire having a carcass ply, the level of dents generated by the carcass ply is dramatically improved as compared with the prior art, and a pneumatic tire having a better appearance can be provided. it can.

It is a longitudinal cross-sectional view of the carcass ply used for the pneumatic tire which concerns on one embodiment of this invention. It is a side view explaining winding of a carcass ply in a pneumatic tire concerning one embodiment of the present invention. It is a longitudinal cross-sectional view explaining the form of the carcass ply in the pneumatic tire which concerns on one embodiment of this invention. It is a cross-sectional view explaining the mechanism of the opening of the carcass ply.

  Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

1. Carcass ply First, a carcass ply used for a pneumatic tire according to an embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view of a carcass ply used in a pneumatic tire according to the present embodiment. In FIG. 1, 1 is a carcass ply, f is a cord, g is a topping rubber, 11 is a cord embedded portion, and 12 is a cord non-embedded portion.

  As shown in FIG. 1, the carcass ply 1 has a topping rubber g coated on both sides of a cord parallel body in which a predetermined number of cords f are juxtaposed at a predetermined spacing between cords (a spacing between the centers of the cords f). And a cord non-embedded portion 12 formed of topping rubber with no cord buried therein. The cord burying portion 11 and the cord non-buried portion 12 are arranged in an alternating manner in the longitudinal direction and are elongated.

  The length W ′ of the cord embedded portion 11 and the length W ′ of the cord non-embedded portion 12 are substantially equal, and the cord embedded portion 11 and the cord non-embedded portion 12 are arranged at substantially equal intervals. Further, the thickness d of the cord non-buried portion 12 is formed to be thinner than the thickness D of the cord buried portion 11.

  Such a carcass ply 1 is produced, for example, by coating a topping rubber on a raw material fabric provided with portions having no cords alternately at a constant interval, using a calendar roll having slits at the same interval. be able to.

2. Next, winding of the carcass ply in the pneumatic tire will be described. FIG. 2 is a side view illustrating winding of the carcass ply in the pneumatic tire according to the present embodiment. As shown in FIG. 2, in the pneumatic tire according to the present embodiment, the carcass ply 1 is wound around the circumference of the tire over two rounds.

  FIG. 3 is a longitudinal sectional view for explaining the form of the carcass ply in the pneumatic tire according to the present embodiment. As shown in FIG. 3 (a), the carcass ply 1 wound around two rounds has a cord embedment portion 11 in the first lap and a cord non-buried portion 12 in the second lap and a cord lap in the first lap. The embedded portion 12 is wound so as to overlap with the cord embedded portion 11 in the second turn.

  After winding in this way, the surface is pressed from the surface of the carcass ply 1 in the second round using, for example, a roller. At this time, as described above, since the lengths of the cord burying portion 11 and the cord non-buried portion 12 are substantially equal, the cord burying portion 11 in the first turn is changed to the cord non-buried portion 12 in the second turn by pressing. The cord burying portion 11 is fitted into the cord non-buried portion 12 in the first round. As a result, as shown in FIG. 3B, the carcass ply 1 with the cords f embedded therein at substantially equal intervals and having a substantially constant thickness is wound.

  By winding the carcass ply as described above, there is no overlap of cords such as an overlap joint and a minimum joint, and there is no occurrence of uneven rigidity on the circumference. As a result, it is possible to provide a pneumatic tire having a dent generation level that is drastically improved as compared with the prior art and having a more excellent appearance.

  In addition, since the joint can be eliminated in a pseudo manner by winding it over two laps, the instability of rigidity in the joint part such as a zipper joint is eliminated, and there is a danger that a mouth opening (open joint) occurs. Therefore, it is possible to improve the dent without impairing the reliability of the tire. And a complicated mechanism such as a zipper joint is not required.

  Thus, according to the present embodiment, since a joint is not required in winding the carcass ply, a pneumatic tire having an excellent appearance with high productivity is provided using inexpensive equipment. Can do.

  In order to prevent the overlapping of the cords f more reliably and to arrange the cords f more evenly when the cords are wound, the cord non-embedded portion 12 in the carcass ply 1 before being wound is It is preferable that the buried portion 11 is disposed at the center of the thickness.

In the carcass ply 1, the length W of the cord burying portion 11 is set to the distance a between the cords in the cord burying portion.
W ≦ 7a
It is preferable that
3a ≦ W ≦ 5a
It is more preferable that the relationship is

  The above shows that in one cord embedding portion 11, 8 or less cords f arranged at an interval a between cords are preferably arranged, and more preferably 4 or more and 6 or less. Yes.

Further, the thickness d of the cord non-embedded portion is smaller than the thickness D of the cord buried portion.
0.2D ≦ d ≦ 0.5D
It is preferable that the relationship is

  That is, when the length W ′ of the cord non-embedded portion 12 is large or the thickness d is thin, the cord non-embedded portion 12 is easily stretched due to insufficient rigidity. Length W 'widens. Thereby, as shown in FIG.4 (b), the wide part 13 of the gauge between codes | corresponds is made locally, it will be in a state like an opening (open cord), a fall of appearance quality, and a fall of tire durability. There is a risk of causing.

  On the other hand, as described above, by setting W ≦ 7a, the spread of W ′ can be suppressed, and by setting 3a ≦ W ≦ 5a, it can be more reliably suppressed. Further, by setting 0.2D ≦ d ≦ 0.5D, it is possible to more reliably suppress the spread of W ′.

  Hereinafter, based on an Example, this invention is demonstrated more concretely.

1. Preparation of evaluation tire (Examples 1 to 6, Comparative Example 1)
In accordance with the above, a carcass ply having a 1-0 HTU structure was wound to produce a 195 / 65R15 PCR type pneumatic tire as an evaluation tire.

The top anti-specs of the carcass ply are as follows.
Cord diameter: 0.68mmφ
Code end: 5.0 / 5cm
Code configuration: 1670 dtex / 2
Top anti-gauge (D): 0.95mm
Length of cord embedded portion W: as described in Table 1 Cord non-embedded portion (no cord portion) rubber thickness d: As described in Table 1

(Comparative Example 1: Conventional tire)
An evaluation tire of Comparative Example 1 was manufactured in the same manner as described above except that the carcass ply was wound by a conventional molded joint (a joint that winds the carcass ply once and overlaps the start and end of winding).

2. Evaluation method and evaluation results (Examples 1 to 6, Comparative Example 1)
(1) Evaluation method The occurrence of carcass ply opening (open code) was examined. The evaluation tire adjusted to an internal pressure of 30 kPa was set in a test apparatus, the FV measurement drum was rotated, the dent amount of the shoulder portion was measured with a distance measurement sensor, and the dent was evaluated. Moreover, durability performance was evaluated.

(2) Evaluation results Table 1 summarizes the evaluation results. In addition, dent evaluation and durability performance were represented by the relative value (index) which made Comparative Example 1 100. The higher the index, the better the performance.

  From Table 1, in Examples 1 to 3, it was found that the dent evaluation was dramatically improved, and the severe market demand 120 or more was cleared and no openings were generated. Moreover, in Examples 4-6, it was confirmed that the performance equivalent to the comparative example 1 which employ | adopted the above-mentioned conventional shaping | molding joint using an expensive joint apparatus is maintained although durability performance is high performance.

  In Examples 1 to 3, the dent evaluation was dramatically improved and the generation of the openings could be eliminated. The carcass ply was formed in a pseudo jointless manner and the overlap of the cords was eliminated. Further, when the distance between the cords is a, the length W of the buried portion of the code is 4a (the distance between the cords f is 5 and the five cords f are used), 5a (the distance between the cords f is 6 with the distance a This is because it is set to a more preferable value, 3a ≦ W ≦ 5a, such as 4a (using the five cords f where a distance between the codes f is a).

  On the other hand, in Examples 4 to 5, the dent evaluation is high performance, but not so much lower than Comparative Example 1 in which the above-described conventional molded joint using an expensive joint device is used. In Example 6, It was found that it was slightly improved as compared with Comparative Example 1. In Example 4, since W was 8a, which exceeded the upper limit 7a of the preferable value, and was too wide, the non-embedded cord portion was stretched, an opening was generated, and durability was lowered. Further, in Example 5, since the rubber thickness d of the cord non-embedded portion was 0.1 D, which was too thin below the preferable lower limit of 0.2 D, the cord non-buried portion was stretched, and an opening was generated, resulting in durability. Decreased. Moreover, in Example 6, since the thickness d of the rubber in the non-embedded portion of the cord was 0.7 D, which was too thick, exceeding the upper limit of 0.5 D, which is a preferable value, the arrangement in the thickness direction of the cord became unstable, and a remarkable effect was obtained. It was not obtained.

  While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

1 Carcass ply 11 Cord buried portion 12 Cord non-buried portion 13 Wide portion of the gauge between cords a Cord distance D Thickness of cord buried portion d Thickness of cord non-buried portion f Cord g Rubber W Length of cord buried portion W ' Length of cord non-buried part

Claims (5)

A pneumatic tire having a carcass ply wound in a circumferential direction,
Cord embedded portions formed by covering a top surface with rubber on both sides of the cord and cord non-embedded portions formed by the topping rubber so as to be thinner than the cord embedded portion are alternately arranged at substantially equal intervals in the longitudinal direction. The arranged carcass ply is wound over two laps,
The cord embedment portion of the first turn of the wound carcass ply is fitted into the cord non-buried portion of the second turn, and the cord embedment portion of the second turn is fitted into the cord non-buried portion of the first turn. And pneumatic tires.   2. The pneumatic tire according to claim 1, wherein the cord non-buried portion is formed by using a carcass ply arranged at a center of thickness of the cord buried portion. The length W of the cord burying portion is set to an interval a between cords in the cord burying portion.
W ≦ 7a
The pneumatic tire according to claim 1, wherein the pneumatic tire is in a relationship of The length W of the cord burying portion is set to an interval a between cords in the cord burying portion.
3a ≦ W ≦ 5a
The pneumatic tire according to claim 3, wherein: The thickness d of the cord non-buried portion is relative to the thickness D of the cord buried portion.
0.2D ≦ d ≦ 0.5D
The pneumatic tire according to claim 1, wherein the pneumatic tire is in a relationship of

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