JPS5848392Y2 - steel cord - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a steel cord used as a reinforcing material for tires, belts, etc.

Generally, this type of steel cord is constructed by twisting a plurality of wires together.

A plurality of these steel cords are lined up in parallel and covered with a rubber material, and are used as reinforcing materials for tires, belts, etc.

Thus, an essential requirement when steel cords are used as reinforcement is good adhesion to the rubber material.

That is, in order for the steel cord to fully fulfill its role as a reinforcing material, it must form a complete composite with rubber.

For example, in the case of a tire, if the adhesion of the steel cord to the comb is poor, a so-called separation phenomenon occurs in which the cord and the rubber material separate during running, which significantly impairs the function of the tire.

Furthermore, if the bonding condition is poor, the wires will rust due to moisture in the rubber or moisture infiltrating from the outside air, resulting in a disadvantage that the strength of the cord will be greatly reduced and the separation phenomenon will be accelerated.

However, the conventional steel cord 1 is formed by twisting a plurality of wires 2 together, as shown in FIG.

Note that in the mouth, 2' indicates the core strand.

At this time, each strand is in close contact with each other, and when covered with a rubber material, the rubber does not penetrate into the center of the steel cord 1 and a space is created at the center of the steel cord 1, causing the steel cord and the rubber to come together. The problem was that the adhesion was not sufficient.

For this reason, recently, gaps C are provided between each strand 2, as shown in Figure 2 A and 2, so that the rubber penetrates to the center of the steel cord and adheres to the entire circumference of the strands. Mildly twisted steel cord 3 (o
(sometimes called pen construction)
is considered.

However, in this case, the loosely twisted steel cord 3 is loosely twisted throughout its longitudinal direction, so as is obvious from its structure, the twist tends to become unstable, and as shown in Figure 2, There are drawbacks such as the cord becoming loose and the twist becoming uneven in the longitudinal direction of the cord, and in such cases, even if the rubber penetrates all the way to the center, the modulus of the composite material is, for example, 5th. As shown in the figure, there are disadvantages such as a decrease in compression bending fatigue properties or worsening of compression bending fatigue properties.

Another drawback is that the multiple strands of the steel cord do not work as a unit, and one or two strands, which are particularly susceptible to stress, break extremely quickly.

However, in reality, the steel cord 3 having the cross-sectional shape shown in FIG.

This is because each element wire must be arranged in space without touching each other.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a steel cord having a structure in which rubber is completely bonded and the twisting is stable.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, 4 indicates the steel cord of the present invention,
2 is the wire, P is the twist pitch, Dl is the cord diameter in the loosely twisted portion, and Dl is the cord diameter in the tightly twisted portion.

In the embodiment shown in FIG. 3A, each strand of the steel cord 4 is twisted so that each pitch (that is, between lightly twisted parts) alternately has lightly twisted parts and tightly twisted parts. ing.

When the steel cord of the present invention having the above structure is coated with a rubber material, the rubber that has permeated into the interior A of the loosely twisted part through the gaps between the strands extends along the length of the cord, as shown in Figure 3, Part 8. The rubber penetrates and fills the tightly twisted part B from the inside, so that the entire surface of the steel cord is covered with rubber.

In addition, since the twists are tightly spaced by one pitch, the stability of the twists can be easily obtained, and a steel cord 4 in which a plurality of wires are integrated can be obtained.

Here, the lower limit of the value of D1/D2, which is the cord diameter DI of the loosely twisted part and the cord diameter D2 of the tightly twisted part, is determined by the degree of rubber penetration as shown in Figure 5. An upper limit is set in order to maintain the physical properties, and it is known that this value is influenced by the structure of the steel cord, the viscosity of the rubber, etc., and is also related to the twist pitch.

For example, in a tire steel cord with ], The rubber penetration rate of
The percentage occupied by rubber in the portion S in the figure is approximately 75% or more.

In addition, the modulus after the rubber is infiltrated is 90 or more compared to 100 for the conventional cord.

Furthermore, this relationship is as shown in FIG.

Incidentally, a steel cord having a core strand is also made of pear as described above.

As mentioned above, the steel cord according to the present invention has tightly twisted parts and loosely twisted parts alternately provided at the required intervals, so that the tightly twisted parts stabilize the strands, and the loosely twisted parts can be stabilized. The twisted part allows space to be given to the strands, resulting in less disorder of the strands and stable twisting.

Furthermore, when a steel cord is coated with a rubber material, the rubber infiltrates from the strand space in the lightly twisted part, and once in the part where the twist is tight enough to prevent rubber from penetrating from the surface, from the lightly twisted part. After penetrating, it is divided into left and right parts, and the space at the center of the cord is penetrated in the longitudinal direction, so that the steel cord can be completely covered with the rubber material, and it can be bonded extremely strongly and the steel cord itself can be reliably rust-proofed.

Furthermore, if the twist is too loose, the mechanical properties such as elongation will change compared to a tightly twisted cord, so it is necessary to make this as small as possible. Therefore, the change in mechanical properties is proportionally small, and it has excellent practical effects such as being able to be handled in the same way as conventional cords.

[Brief explanation of drawings]

Fig. 1 A 9 and Fig. 2 A 9, C, 2, and H are cross-sectional views showing conventional steel cords, Fig. 3 shows an embodiment of the steel cord of the present invention, and A is a front view. , mouth is D
Figure 4 is an explanatory diagram when the steel cord of the present invention is used; Figure 5 is the degree of rubber penetration of the steel cord of the present invention. FIG. 1.3.4...Steel cord, 2...
・Element wire, Dl...Cord diameter of loosely twisted part, Dl...Cord diameter of tightly twisted part.

Claims (1)

[Scope of utility model registration request] In a steel cord made by twisting a plurality of strands, lightly twisted parts and tightly twisted parts are alternately constituted, and the loosely twisted parts are set to -pitch, and the cord diameter of the lightly twisted part is D1. A steel cord characterized in that the cord diameter D2 of the tightened portion has a ratio D1/D2=1.1 to 1.4.