JP2007023400A - Steel cord for reinforcement of rubber article and pneumatic tire produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel cord for the reinforcement of a rubber article to further improve the peel-prevention effect of the rubber from a terminal of a steel cord and provide a pneumatic tire produced by using the cord. <P>SOLUTION: The steel cord S for the reinforcement of a rubber article is produced by twisting a plurality of element wires (w) in the form of a plurality of layers 1, 2, 3 having n+m+.. structure, and shifting the terminals of the multiple layers 1, 2, 3 in one longitudinal direction from the inner layer toward the outer layer while keeping the shift lengths (a) and (b) between the adjacent layers to 5-20 mm. The pneumatic tire T contains the steel cord as a reinforcing layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a steel cord for reinforcing rubber articles and a pneumatic tire using the same, and more specifically, a steel cord for reinforcing rubber articles and a steel cord for reinforcing rubber articles that further improve the effect of preventing separation from rubber from a steel cord terminal. The present invention relates to a pneumatic tire excellent in durability using the same.

  Steel cords having high strength and high elastic modulus are used as reinforcement cords in many rubber articles including pneumatic tires. In rubber articles that use such steel cords as a reinforcing layer, especially tires that are subjected to large load loads, stress concentrates on the ends of the steel cords due to repeated deformation during traveling, and the rubber cords peel off from the ends of the steel cords. There is a problem that it is likely to occur.

Conventionally, as a countermeasure, the cord density is reduced in the end region of the reinforcing layer (see, for example, Patent Document 1), or internal stress is applied in advance to some strands constituting the steel cord and twisted ( For example, there is a proposal as described in Patent Document 2. However, although any of the proposals shows a temporary peeling prevention effect, some rubber articles are required to obtain durability at a higher level.
Japanese Patent Laid-Open No. 9-2016 JP-A-7-90784

  SUMMARY OF THE INVENTION An object of the present invention is to meet such a conventional request, and to provide a steel cord for reinforcing rubber articles and a pneumatic tire using the same, in which the effect of preventing separation from rubber from a steel cord terminal is further improved. It is to provide.

  In order to achieve the above object, a steel cord for reinforcing a rubber article according to the present invention is a steel cord for reinforcing a rubber article obtained by twisting a plurality of wire wires into a plurality of layers of an n + m + .. structure. The terminal is shifted in one longitudinal direction from the inner layer to the outer layer, and the shift length between adjacent layers is 5 to 20 mm.

  The pneumatic tire of the present invention is characterized by using the above-described steel cord for reinforcing rubber articles as a reinforcing layer.

  According to the present invention, when a steel cord composed of a plurality of layers of n + m + .. structure is used as a reinforcing layer of a rubber article, the ends of each layer of the steel cord are sequentially shifted, and the shift length is 5 to 20 mm. Therefore, the rigidity in the end area of the steel cord gradually decreases toward the end of the cord, so that concentration of stress applied to the end of the steel cord is alleviated and rubber from the end of the steel cord is reduced. Peeling can be suppressed.

  Therefore, the durability of the rubber article is improved, and in particular, the durability of the tire can be improved by using the steel cord having the above configuration as a reinforcing layer such as a carcass layer or a belt layer of a pneumatic tire.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  1 is a perspective view showing a terminal portion of a steel cord for reinforcing rubber articles (hereinafter simply referred to as a steel cord) according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view in the radial direction of the steel cord of FIG. FIG. 3 is a longitudinal sectional view showing the layers in the end portion of the steel cord of FIG. 1 in an integrated manner.

  The steel cord of the present invention is constituted by twisting a plurality of strand wires into a plurality of layers of an n + m + .. structure. 1 to 3, the steel cord S is composed of a strand in which the innermost layer 1 is formed by twisting three strand wires w, and this strand is used as a core, on which the nine strand wires w are formed as an intermediate layer 2. And a three-layer twisted 3 + 9 + 15 structure in which 15 strand wires w are twisted as the outermost layer 3 thereon.

  Then, as shown in FIGS. 1 and 3, the terminals of the respective layers 1, 2, and 3 are sequentially shifted by a and b in one longitudinal direction (right side in the figure), and the shift length between the adjacent layers is set. Each of a and b is 5 to 20 mm, preferably 5 to 10 mm.

  As described above, since the ends of the respective layers 1, 2, and 3 are sequentially shifted in one longitudinal direction, and the shift lengths a and b thereof are set to 5 to 20 mm, the rigidity in the end area of the steel cord S is the core. By gradually decreasing toward the end of the cord, the stress concentration applied to the end of the steel cord S in the rubber article using the steel cord S as a reinforcing layer is alleviated, and the rubber from the end of the steel cord is reduced. Peeling can be suppressed.

  If the shift lengths a and b described above are less than 5 mm, peeling of the steel cord from the rubber end cannot be sufficiently suppressed, and if it exceeds 20 mm, the rigidity of the steel cord is insufficient and a sufficient reinforcing effect cannot be obtained.

  In the above-described embodiment, the case where the steel cord S is a three-layer twist is illustrated, but the number of layers is not limited to this and may be a two-layer twist structure. However, in order to sufficiently exhibit the above-described effects, a three-layer twist structure is preferable.

  FIG. 4 shows another embodiment of the present invention, in which the ends of the respective wire layers 1, 2, and 3 are directed from the outer layer toward the inner layer in directions opposite to those in FIGS. 1 and 3 (right side in the figure). ) Shows a case where a and b are shifted and laminated.

  The steel cord S of the present invention may have both end portions as shown in FIGS. 1 and 3 and both end portions as shown in FIG. However, considering the forming process of the steel cord S, it is preferable that one end is in the form of FIG. 1 and FIG. 3 and the other end is in the form of FIG. That is, after cutting both ends of the steel cord S twisted into three layers, the innermost wire layer 1 and the intermediate wire layer 2 can be pulled out in one longitudinal direction and formed.

  The steel cord S of the present invention can be applied to various rubber articles including a pneumatic tire. In particular, it is suitable for reinforcing a pneumatic tire that is subjected to repeated load deformation during traveling and is susceptible to separation at the end portion of the steel cord S.

  FIG. 5 is a half sectional view showing a pneumatic tire using the steel cord S of the present invention as a reinforcing layer. In FIG. 5, the pneumatic tire T includes left and right bead portions 4 and 4 and a tread portion 5, and a carcass layer 7 is formed around the bead cores 6 and 6 embedded in the bead portions 4 and 4 from the inside to the outside of the tire. It is mounted so that it wraps around. Two belt layers 8 and 9 are arranged on the outer periphery of the carcass layer 7 in the tread portion 5. The steel cord S described above is used for the carcass layer 7 and the belt layers 8 and 9.

  When the steel cord S of the present invention is used as a tire reinforcing cord, the ends of the steel cord S are preferably arranged so as to be shifted from each other in the longitudinal direction as illustrated in FIG. Thereby, peeling with the rubber | gum from the terminal of the steel cord S can be suppressed effectively. Note that the arrangement of the steel cords S is not limited to the case where the dimensions c are shifted between adjacent cords as illustrated in FIG. 6, and the steel cords S are shifted every two to three adjacent steel cords S. Also good.

  As described above, the steel cord of the present invention reinforces the rubber article by shifting the ends of each layer twisted into a plurality of layers by a predetermined amount in one longitudinal direction from the inner layer to the outer layer. It suppresses the peeling of the steel cord from the end of the steel cord when used as a cord, and is particularly suitable for reinforcing heavy-duty pneumatic tires such as trucks and buses with a large load.

  When manufacturing a steel cord having a 3 + 9 + 15 structure using a 0.15 mm wire, one end portion was formed as shown in FIGS. 1 and 3, and the other end portion was formed as shown in FIG. A reinforcing layer is manufactured by varying the shift lengths a and b of each wire layer end of the steel cord and the shift length c of the adjacent cord ends as shown in Table 1, and this is made up of 315 having the structure of FIG. A conventional tire (conventional example), a tire of the present invention (Examples 1 and 2) and a comparative tire (Comparative Examples 1 and 2) used as a carcass layer of a tire of /80R22.5 size were manufactured.

The above five types of tires were each filled with an air pressure of 900 kPa, and an endurance test was performed with an indoor drum tester under the conditions of a load of 45 kN and a speed of 45 km / hour. The results are also shown in Table 1 using an index with the conventional tire as 100. It shows that durability is excellent, so that a numerical value is large.

  From Table 1, it can be seen that the tire of the present invention is superior in durability compared to the conventional tire and the comparative tire.

It is a perspective view which shows an example of the terminal part of the steel cord by embodiment of this invention. It is an expanded sectional view which shows the radial direction cross section of the steel cord of FIG. It is sectional drawing of the longitudinal direction which shows each layer in the terminal part of the steel cord of FIG. FIG. 4 is a cross-sectional view corresponding to FIG. 3 according to another embodiment of the present invention. 1 is a half sectional view showing a pneumatic tire according to an embodiment of the present invention. It is a top view which shows an example of arrangement | positioning of the steel cord in the reinforcement layer by embodiment of this invention.

Explanation of symbols

1, 2, 3 layers 4 bead portion 5 tread portion 6 bead core 7 carcass layer 8, 9 belt layer w wire strand S steel cord T pneumatic tire

Claims (5)

In a steel cord for reinforcing rubber articles formed by twisting a plurality of wire wires into a plurality of layers of n + m + .. structure,
A steel cord for reinforcing rubber articles in which the terminals of the plurality of layers are shifted in one longitudinal direction from an inner layer to an outer layer, and a shift length between adjacent layers is 5 to 20 mm.   The steel cord for reinforcing rubber articles according to claim 1, wherein the number of the layers is three.   The steel cord for reinforcing rubber articles according to claim 1 or 2, wherein an end portion of the wire wire forms a notch in the longitudinal direction.   A pneumatic tire using the steel cord for reinforcing rubber articles according to claim 1, 2 or 3 as a reinforcing layer. The pneumatic tire according to claim 4, wherein ends of the steel cord for reinforcing rubber articles are arranged on the reinforcing layer so as to be shifted from each other in the longitudinal direction.

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