JPS593281B2 - Reinforcement cord for tire outer skin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reinforcing cord for reinforcing a reinforcing layer of a tire outer skin.

FR 1 427 886 describes a tire tread reinforcement layer consisting essentially of two diagonal layers.

The first of these two layers is reinforced with a relatively rigid metal cord, and the second layer, folded around the edge of the first layer, is optionally reinforced with a relatively flexible metal cord. has been done.

Such an arrangement facilitates folding of the folded layer while still minimizing damage to the cord in the folding area.

French Patents Nos. 7,145,193 and 7,433,606 describe a special arrangement of cords in a tread layer consisting of at least one folded diagonal layer reinforced with metal cords.

This arrangement is to prevent fatigue failure of the cord in the fold area.

If the S-shaped and 2-shaped layers, respectively, are reinforcing layers consisting of cords having slopes in the same direction as the center of the letters S and 2, respectively, to an observer outside the tire, and the S-shaped A Z-shaped cord is still a cord in which the exposed portion of each strand (or each element line in the case of no strand) has an inclination relative to the observer of the cord in the same direction as the central part of the letters S and Z, respectively. If so, the above-mentioned French patents '7145193 and 7433606
The structure published in No. 1 is aimed at loosening the cord in the folded area of the top layer.

For this purpose, when the reinforcing layer appears to be of the same shape as the metal cord (S-shape or 2-shape), the folded portion(s) of this reinforcing layer may be folded to the outside of the respective portion ( 2 or S
) and a different type (S or Z), it is recommended to place the folded part inside the unfolded part.

As a result of the applicant's research, if a code with a special structure is used,
The discovery that not only the use of folded layers in tread reinforcement structures, but also whatever tire skin area uses this type of layer, can result in a significant improvement in the fatigue resistance of the cord in the folds Reached.

The invention is based on the following observations.

First, the element wire breaks due to fatigue at the outer periphery of the cord in the fold area.

Secondly, the magnitude of the local torsion within the folded area obtained by the above-described placement method is related to the pinch value of the element line for a given slope of the folded reinforcement layer.

However, according to a preferred embodiment of the present invention, it is desirable to limit the pitch of the strands to a value that is 1/10 or more of the pitch of the element lines.

This is to prevent an element line assembly lacking the basic characteristics of the code.

It goes without saying that the invention extends not only to reinforcing layers such as those described above which may be used for reinforcing the tire skin, but also to metal cords of the type described above.

The cord may be of the so-called elastic type, ie consisting of spaced strands.

The cord may be coreless and consist of a single layer of strands, but it can also have a core consisting of at least one elemental wire.

In the case of multi-core wires, the cord can exhibit the following structural variations:

In the first embodiment, the core, strand, and cord are of the same type (S or 2).

In a second embodiment, the strand and the cord are the same.
type (S and Z), but the core wire is of a different type (2 or S
).

Preferably, in the reinforcing layer according to the invention a cord corresponding to the first embodiment is used.

However, in a few cases, especially when the angle of the reinforcing layer with respect to the direction of the folding line is a dog, it is possible to use a cord corresponding to the second embodiment.

According to the invention, when the cord is folded, the outer strands of the cord open from each other and optionally separate from the core wire, and the element wires within each strand separate from each other.

This facilitates the penetration of the calendaring rubber of the cord layer into the middle of each component of the cord and the mutual separation of the cord components.

Hereinafter, the present invention will be explained in detail with reference to examples shown in the drawings, but the present invention is not limited to these examples.

In Figures 1 and 2, Figure 1 shows a cord consisting of strands 1 assembled in an S-shape around the axis XX of the cord, and Figure 2 shows a cord consisting of strands 2 assembled in a 2-shape as well. shows.

3 and 4 respectively show the S-shaped layer 3 (FIG. 3) with S-shaped cords 31 according to the invention folded closer to the viewer and the reinforcement with two-shaped cords 32. FIG. 5 is a diagram showing layer 3 (FIG. 4) folded in a direction away from the viewer;

5 and 6, FIG. 5 shows a cross section of a cord having a single core wire 5 surrounded by four strands 6 each consisting of four element wires 61, and FIG. 1 shows a cross-section of a cord made up of four strands 7 each consisting of an element line 71;

FIGS. 7 and 8 show two embodiments of the multi-wire core cord described above, with parts of each layer thereof being sequentially disassembled and illustrated.

In FIG. 7, a portion of the code 10 according to the first embodiment can be seen.

The core wire 8, the four strands 9 and the cord 10 have the same S-shape.

The core wire 8 consists of three element wires 81, and the four strands 9 each consist of four element wires 91.

In FIG. 8, a portion of the cord 20 according to the second embodiment can be seen.

The core wire 21 is Z-shaped and has three element wires 23, whereas the four strands 22 each consisting of four element wires and the entire cord 20 are S-shaped.

The reinforcing cord has a reinforcing member including at least one diagonal layer of bent metal cord;
If this layer has the same type of appearance (S or Z) as said metal cord, the folded part of this layer is placed outside the unfolded part (with respect to the tire skin) or When the reinforcing layer has an appearance of a type (S-! or 2) different from the type (2 or S) of the metal cord, the bent portion is placed inside the unbent portion, and the metal cord is The exposed outer layer of is applied to a tire skin comprised of strands each consisting of at least two element wires.

[Brief explanation of the drawing]

Figures 1 and 2 are partial side views of cords with strands assembled in an S-shape and a 2-shape, respectively, and Figures 3 and 4 are perspective views showing reinforcing layers with S-shape and Z-shape cords, respectively. 5 and 6 are cross-sectional views of a cord with a single core and a cord without a core, respectively, and FIGS. 7 and 8 are two embodiments of a multi-wire cord according to the present invention. FIG. 1.2... Strand, 3... Reinforcement layer, 5... Single core wire, 6, 7... Strand, 8... S type multi-wire core wire, 9... S type strand, 10...S type code,
21...Z type multi-wire core wire, 22...S type strand,
23...Element line, 31.32...Code, 61,7
1,81°91...element line.

Claims (1)

[Scope of Claims] 1. A reinforcing cord for a tire outer skin constructed by twisting together metal strands consisting of at least two element wires with exposed outer layers twisted together, wherein the strands of the outer layer constitute strands. A reinforcing cord characterized in that it has a pitch in the same direction that is smaller than the pitch of the element lines. 2 The pitch of the strands is one-tenth of the pitch of the element lines
Reinforcement cord according to claim 1, characterized in that it is more dog-like.