JP2005193771A - Pneumatic tire and manufacturing method for pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire which can prevent BES from propagating, and can extend the service life of the tire. <P>SOLUTION: This pneumatic tire 100 is equipped with at least one layer of a belt layer 6 on the periphery of the crown section of a carcass 5. The belt layer 6 is formed by combining a plurality of coated cords 7 on the periphery. A cord interval L1 in the combined section 8 of the end section regions 10 and 12 of the coated cord 7 is set to be wider by 1.5 to 4 times compared with another cord interval L2 which is adjacent to the cord interval L1. Also, such a spot having the wider cord interval (end section region wider width section) is provided at four locations or more per tire in the end section regions 10 and 12 of the coated cord 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire having a belt layer formed by bonding a coated cord formed by coding a cord with rubber, and a method for manufacturing the pneumatic tire.

  The belt layer of a pneumatic radial tire functions as a radial tire shape retention and strength member, and is an important member that affects various tire performances such as durability performance, steering stability performance, rolling resistance performance, and riding comfort. The conventional belt layer is composed of steel cords arranged in parallel, covered with coding rubber, and two layers laminated at a crossing angle of 15 to 30 degrees with respect to the tire equator line. ing. The belt layer is formed by joining a plurality of coated cords coated with a coating rubber in the tire circumferential direction.

Normally, the gap between the steel cords arranged in parallel is constant in any part of the belt layer (for example, see Patent Documents 1 to 3).
Japanese Patent Laid-Open No. 5-269887 JP-A-6-316001 Japanese Patent Laid-Open No. 5-92701

  However, the end of the belt is subjected to compression, tension, or thermal history due to rolling of the tire, and depending on the usage environment, it may cause adhesive failure with the surrounding rubber, and the belt edge separation (hereinafter, “ "BES") leads to tire deformation and tread peeling when connected to the circumferential direction of the tire.

  On the other hand, in recent years, demands for weight reduction of tires from the market and automobile manufacturers are increasing due to reasons such as improvement in fuel consumption, and therefore, weight reduction of members used for tires is necessary. Regarding the belt portion, there is a tendency to use a belt layer that is lightweight and has high rigidity due to the thinning of the belt cord and the increase in the number of driving.

  The cord gap at the end of the belt layer that has been highly driven is set narrower than the cord gap of the belt layer that has been conventionally used before the weight reduction, and the BES is easily connected in the circumferential direction. When such a narrow cord gap is set on the entire circumference of the tire, there is a possibility that the life of the tire may be shorter than the conventional one before weight reduction.

  In addition, there is a conventional technique (for example, see Patent Document 3) in which the belt gap is made staggered to increase the cord gap and improve the BES. However, it is technically possible to cut the edge into a zigzag pattern. It was very difficult.

  Then, in view of said problem, this invention aims at providing the manufacturing method of the pneumatic tire which can prevent propagation of BES, and can extend the lifetime of a tire, and a pneumatic tire.

  In order to solve the above-mentioned problems, a first feature of the present invention is a pneumatic tire having a belt layer formed by joining a coated cord formed by coding a cord with rubber, and an end portion of the coated cord The gist of the present invention is a pneumatic tire in which one cord gap in a region has four or more places per tire set to be 1.5 to 4 times wider than other cord gaps adjacent to one cord gap. To do. Here, the “end region” refers to a region within 20% of the belt width from the end of the coated cord.

  According to the pneumatic tire according to the first feature, in the end region of the coated cord, a plurality of locations having a cord gap wider than the adjacent cord gap are provided at a plurality of locations on the tire circumference, thereby trying to connect to the circumference. Propagation of BES can be prevented and the life of the tire can be extended. Further, by providing such a wide cord gap in the highly driven belt layer, it is possible to meet the demand for reducing the weight of the tire.

  In addition, the pneumatic tire according to the first feature needs to be provided with four or more locations where the cord gap is 1.5 to 4 times wider (hereinafter referred to as “wide portions”). Here, the reason for defining 1.5 to 4 times is that if it is smaller than 1.5 times, it is almost the same as the adjacent cord gap, and the effect of the present invention cannot be expected. Since the strength and rigidity of the steel sheet are lowered, the uniformity is deteriorated and uneven wear occurs, and the penetration of nails or the like cannot be prevented, so that the occurrence rate of puncture is increased. Moreover, if the wide part is 3 or less, the effect of suppressing the propagation of cracks in BES does not appear.

  In the pneumatic tire according to the first feature, it is desirable that one cord gap in the center area of the coated cord is 1.5 times or less than other cord gaps adjacent to the one cord gap. Here, the “center region” refers to a region within 40% of the belt width with the center of the coated cord as the center. When the cord gap is larger than 1.5 times, the rigidity in the tire circumferential direction is lowered, which may cause a decrease in steering stability and a deterioration in uniformity.

  Moreover, in the pneumatic tire according to the first feature, it is further desirable to have eight or more locations per tire that are set 1.5 to 4 times wider than the end region. When the number is 8 or more, the effect of preventing the propagation of BES trying to be connected to the periphery is further enhanced, and the life of the tire can be further extended.

  A second feature of the present invention is a method of manufacturing a pneumatic tire having a belt layer formed by joining a coated cord formed by coding a cord with rubber, and one cord in an end region of the coated cord The gist of the present invention is a method for manufacturing a pneumatic tire, in which four or more locations per tire are set that are 1.5 to 4 times wider than other cord gaps adjacent to one cord gap.

  According to the method for manufacturing a tire according to the second feature, it is possible to prevent the propagation of BES trying to be connected to the periphery and to manufacture a pneumatic tire having a long life.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the pneumatic tire which can prevent propagation of BES and can extend the lifetime of a tire, and a pneumatic tire can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Composition of pneumatic tire)
As shown in FIG. 1, a pneumatic tire 100 according to an embodiment of the present invention includes a pair of bead portions 1 and a pair of sidewall portions 2, and a tread portion 3 that is continuous in a toroid shape between the sidewall portions 2. Is provided. The carcass 5 is a toroidal radial carcass that reinforces the bead portion 1, the sidewall portion 2, and the tread portion 3 between a pair of bead cores 4 embedded in the bead portion 1. The belt layer 6 of the layer or more is arranged, and the tread portion 3 is reinforced. In FIG. 1, two belt layers 6 are laminated.

  FIG. 2 is a plan view of the belt layer 6 developed in the tire circumferential direction (arrow A direction) and viewed from the tire surface. The belt layer 6 is formed by coupling a plurality of coated cords 7 in the tire circumferential direction. A portion where the coated cord 7 is coupled is defined as a coupling portion 8. Moreover, the area | region of the range within 20% with respect to the belt width W of a tire width direction (arrow B direction) from the coated cord edge part is made into the edge part area | regions 10 and 11. FIG. An area within 40% of the belt width W around the center C of the coated cord 7 is defined as a center area 11.

  Next, FIG. 3 shows a tire circumferential direction sectional view of the end regions 10 and 12 of the coated cord 7. The coated cord 7 is obtained by coating a rubber 13 on a cord 14 made of organic fiber and steel wire. The cord gap L1 (wide portion gap) in the coupling portion 8 of the end regions 10 and 12 is set to be 1.5 to 4 times wider than the other cord gap L2 (normal gap) adjacent to the cord gap L1. . Further, in the end regions 10 and 12 of the coated cord 7, there are four or more portions (end region wide portions) having such a wide code gap per tire. Furthermore, it is good also as having eight or more edge part area wide parts.

  Next, a sectional view in the tire circumferential direction in the center region 11 of the coated cord 7 is shown in FIG. In the center region 11, the gap L3 (wide portion gap) where the cord gap is wide (center region wide portion) is 1.5 times or less than the other cord gap L4 (normal gap) adjacent to the cord gap L3. Is set. That is, in the center region 11, the code gap is substantially constant.

(Pneumatic tire manufacturing method)
Next, the manufacturing method of the pneumatic tire mentioned above, ie, the pneumatic tire which has in the belt layer 6 the edge part wide part which is 4 places or more, or 8 places or more is demonstrated.

  As shown in FIG. 3 and FIG. 4, the coated cord 7 is a cord 14 made of organic fibers and steel wires, and is coated with a rubber 13 by a calender. They are cut into widths and angles, combined and wound up on a conveyor. As this coupling method, conventionally, an overlap joint that couples a part of the coated cord in an overlapping manner, a pad joint that joins the end portions of the coated cord or the like, and the like are used.

  When the pneumatic tire according to the present embodiment is manufactured, the gauge of the rubber 13 of the connecting portion 8 is made thin when the coated cord 7 is connected. Then, since the thin rubber portion is stretched as compared with other portions due to the expansion when the tire is vulcanized, the cord gap is set wide when the product is manufactured.

  In addition, in the belt layer 6 having a small number of coupling portions 8, by cutting in advance at the end portion of the coated cord 7, the cord gap at the time of becoming a product is set wide due to the expansion at the time of vulcanization.

  In recent years, a manufacturing method that does not expand the tire during vulcanization has been developed. In this case, when the belt layer 6 is manufactured, the above-mentioned manufacturing is performed by setting the joint so that the cord gap is widened in advance. A wide code gap similar to the method can be obtained.

(Operation and effect of the pneumatic tire and the manufacturing method according to the present embodiment)
According to the pneumatic tire according to the present embodiment, the belt layer 6 has four or more end region wide portions, thereby widening the cord gap and preventing the propagation of BES trying to connect to the circumference. For this reason, the lifetime of a tire can be extended.

  In addition, by making the cord gap in the wide end portion area 1.5 to 4 times that of the adjacent cord gap, the cord gap is moderate, so that the strength and rigidity of the belt end are prevented from being lowered and the uniformity deteriorated. Uneven wear does not occur, and the occurrence rate of puncture due to penetration of nails or the like can be kept low.

  Moreover, by making the cord gap of the center region wide portion 1.5 times or less of the adjacent cord gap, it is possible to prevent the tire circumferential rigidity from being lowered and to maintain good steering stability and uniformity.

  Moreover, according to the manufacturing method of the pneumatic tire which concerns on this embodiment, in the belt layer 6, the pneumatic tire which has an edge part area wide part 4 places or more, or 8 places or more can be manufactured. Further, in the method for manufacturing a pneumatic tire according to the present embodiment, the cord gap in the end region of the coated cord 7 is set wide, so that the center region wide portion interval is constant at 1.5 times or less of the normal interval. can do.

  Examples of the pneumatic tire according to the embodiment of the present invention will be described in detail below. In order to confirm the effect of the present invention, three types of tires of the example to which the present invention was applied and one type of conventional tire were mounted on the rim, and the travel distance until failure was measured.

  In both the example and the conventional example, the tire size was 195 / 65R15, the rim was 6J-15, and the internal pressure was 210 kPa. In this embodiment, the rim diameter, the internal pressure, etc. conform to the TRA standard. In addition, Honda's Accord (sedan) was used as an evaluation vehicle.

  Test conditions of Examples 1 to 3 and the conventional example are as shown in Table 1. In the conventional example, the end region wide portion gap was 1.2 times the normal gap, and the center region wide portion gap was 1.0 times the normal gap. On the other hand, in Examples 1 to 3, the end region wide portion gap was 2.2 times the normal gap, and the center region wide portion gap was 1.7 times the normal gap.

Further, the travel distance until the failure is represented by an index with the conventional example being 100, and the longer the value, the longer the service life.

(result)
Example 1 had the same travel distance as the conventional example. Therefore, in the tire having three end region wide portions, the effect of extending the life could not be obtained.

  On the other hand, in Example 2 and Example 3, the travel distance until failure is longer than in the conventional example. Therefore, it can be seen that a tire having four or more end region wide portions has a long life. Further, in Example 3, the traveling distance has been dramatically increased, so that it can be seen that the life of the tire having eight or more end region wide portions is further increased.

1 is a cross-sectional view including a tire rotation axis of a pneumatic tire according to an embodiment of the present invention. It is a top view of the belt layer of the pneumatic tire concerning the embodiment of the present invention. It is a tire peripheral direction sectional view of a belt layer of a pneumatic tire concerning an embodiment of the present invention (the 1). It is a tire peripheral direction sectional view of the belt layer of the pneumatic tire concerning the embodiment of the present invention (the 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bead part 2 ... Side wall part 3 ... Tread part 4 ... Bead core 5 ... Carcass 6 ... Belt layer 7 ... Coated cord 8 ... Coupling part 10, 12 ... End part area | region 11 ... Center area | region 13 ... Rubber | gum 14 ... Code | cord 100 ... Pneumatic tire

Claims (4)

A pneumatic tire having a belt layer formed by bonding a coated cord formed by coding a cord with rubber,
One cord gap in the end region of the coated cord has four or more places per tire that are set 1.5 to 4 times wider than other cord gaps adjacent to the one cord gap. A featured pneumatic tire.   2. The pneumatic tire according to claim 1, wherein one cord gap in the center area of the coated cord is 1.5 times or less than another cord gap adjacent to the one cord gap.   3. The pneumatic tire according to claim 1, wherein the tire has eight or more locations that are set to be 1.5 to 4 times wider than the end region. A method of manufacturing a pneumatic tire having a belt layer formed by combining a coated cord formed by coding a cord with rubber,
4 or more locations per tire are set such that one cord gap in the end region of the coated cord is set to be 1.5 to 4 times wider than other cord gaps adjacent to the one cord gap. A method for producing a pneumatic tire.

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