JPS644878Y2 - - Google Patents

Description

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

Conventional technology and its problems In general, this type of steel cord is constructed by twisting a plurality of strands of strands, for example, as shown in Figure 4 A and B, 4 or 5 identical strands 2 are twisted together. The steel cord 1 is formed by twisting them together.

A plurality of these steel cords 1 are arranged in parallel and covered with a rubber material, and are used as a rubber reinforcing material for tires, belts, etc. Thus, the essential requirements when steel cord is used as reinforcement are:
It must chemically adhere well to the rubber material, and the rubber material can penetrate well into the steel cord. That is, in order for the steel cord to fully fulfill its role as a rubber reinforcing material, it is necessary that it be a complete composite with the rubber material.

For example, when used in tires, if the adhesion between the steel cord and the rubber material and the infiltration of the rubber material into the steel cord are poor, a so-called separation phenomenon occurs in which the steel cord and the rubber material separate when the car is running. In addition to significantly impeding the function of the tire, moisture in the rubber and moisture that has entered through cuts in the rubber travels through the air A inside the steel cord and reaches the inside of the tire, causing rust to occur in the steel cord wires, causing the steel cord to become rusty. It has the disadvantage of greatly reducing the strength of the material and accelerating the separation phenomenon described above.

For this reason, recently, steel cords have been developed in which the rubber material penetrates into the center of the steel cord and is adhered to the entire circumference of the strands. As shown in FIGS. 5A and 5B, this steel cord is a lightly twisted steel cord 1 which is twisted together with a gap C between each strand 2.

However, in the above-mentioned lightly twisted steel cord, in order to ensure that the rubber material adheres to the entire circumference of each strand and that the rubber material penetrates into the interior, it is necessary for the rubber material to penetrate into the gap C between each strand. It is necessary to provide sufficient spacing, that is, 0.02 mm or more. However, if a sufficient gap C is provided between each strand, the twisted structure tends to become unstable during pressure vulcanization of the steel cord and rubber material, as shown in Figure 6 A and B. The wire 2 may become offset or the twist may become uneven in the longitudinal direction of the steel cord. In such a case, even if the rubber material penetrates into the steel cord, the elongation will be large under very low loads, which will have a negative impact on tire manufacturing operations, and if the steel cord buckles, the stress will increase. The drawback is that concentration occurs, and the multiple strands that make up the steel cord do not work as a unit, leading to fatigue failure.

Means for Solving the Problems The present invention was devised to eliminate the above-mentioned drawbacks, and is designed to ensure that the rubber material does not penetrate into the steel cord, and that the rubber material and the steel cord are bonded securely. suppresses elongation under low loads,
Furthermore, the present invention provides a steel cord with stable twisting in the longitudinal direction and improved fatigue resistance.

In order to achieve the above object, the present invention has developed a single-layer twisted steel cord in which four or five wires having the same wire diameter are twisted in the same direction and at the same pitch. Twist them almost together,
At least one of the other two or three strands is twisted together in contact with one of the two strands, so that there is no closed space between the strands. It is a steel cord characterized by its structure.

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1A, 1B, 1C and 1D are cross-sectional views showing one embodiment of the steel cord of the present invention. In Fig. 1A, the strands 3, 3 are twisted together in close contact with each other in an S twist with a twist pitch of 12.5 mm, and two strands 4, 4 are arranged almost in contact with one of the strands 3, respectively. and at least between the strands 4 and 4.
They are arranged with a gap C of 0.02mm, and the strands 4, 4 are twisted around the strands 3, 3 in the same direction and at the same pitch as the strands 3, 3, and each strand is connected to the strands. A steel cord 5 having no closed space is constructed.

Next, the steel cord 5 shown in FIG.
Arranged so that there is a gap C between the strands 3 and 4,
The wires are twisted together in the same manner as described above, and each strand is constructed so that there is no closed space anywhere. Further, the steel cord 5 shown in Figure C is almost the same as the above B, except that the arrangement of the strands 4, 4 is different, and the steel cord 5 shown in Figure 2 is based on one of the base wires 3. The strands 4 on one side of the periphery are arranged so as to be substantially in contact with the strands 4, and the strands 4 on the other periphery are arranged so as to have a gap C with respect to the strands 3 serving as the base.

Incidentally, the wire diameters of the wires 3 and 4 are both 0.25 mmφ. In addition, the wire used in the present invention may be plated with copper alloy on the surface in order to improve adhesion to the rubber material, and the wire diameter is approximately 0.15 mm to 0.5 mm. The twist pitch is preferably in the range of 6 mm to 20 mm.
The reason why the gap C is set to be 0.02 mm or more is that if it becomes narrower than 0.02 mm, even if the rubber material has good fluidity during pressure vulcanization, the rubber material will seep into the gap between the steel cords. This is because the adhesion between the steel cord and rubber deteriorates, and spaces tend to form inside.

Embodiment 2 Other embodiments of the present invention constructed with five strands of wire are shown in FIGS. 2A, 2B, 2C, and 2, respectively.

In Fig. 2A, the strands 3, 3 are arranged in close contact with each other and are twisted together in an S twist with a twist pitch of 12.5 mm, and one strand 3 has three strands 4,
4 and 4 are arranged substantially in contact with each other, and at least one of the strands 4 and 3 is arranged between the strands 4 and 3 of the other strand.
They are arranged with a gap C of 0.02 mm, and three strands 4 are arranged around the strand 3 in the same direction as the strand 3.
Steel cord 5 which is twisted together at the same pitch and has no closed space anywhere due to the five strands mentioned above.
Configure.

Next, the steel cord 5 in B of the figure is attached to one of the base wires 3, 3 with a small gap between the wires 3 and 3.
The strands 4, 4, 4 around the book are arranged so that there is a gap C between one of the strands 4 and the other strand 3, and each strand is twisted in the same manner as above. It is constructed using strands of wire so that there is no enclosed space anywhere. In addition, in the steel cord 5 shown in FIG.
4 with a gap C between them, and the remaining circumferential strand 4 is arranged almost in contact with the other strand 3 serving as the base, and the steel cord shown in FIG. 5 is arranged so that each of the two circumferential strands 4, 4 is almost in contact with each of the base strands 3, 3 at the same side position, and the remaining one circumferential strand 4 is placed on the opposite side. The arrangement is such that there is a gap C with respect to the base wire 3 at the side position.

By the way, in the above-mentioned Examples 1 and 2, the base wires 3 were closely attached to each other, but depending on the case, they may be twisted so that they are almost in contact with each other.

The steel cord of the present invention can be formed by first twisting two basic strands 3 that are in contact with each other, and then twisting the surrounding strands 4 around them while twisting them with pins or the like. be.

Next, FIG. 3 shows a load-elongation curve diagram of the steel cord of the present invention and the conventional steel cord. In the figure, X is the conventional steel cord shown in FIG. 4 (b), Y is the steel cord of the present invention shown in FIG. 1 (a), and Z is the conventional loosely twisted steel cord shown in FIG.

When the steel cord Y of the present invention was pulled under a load of 5 kg, the elongation was approximately 0.3%, which was approximately 1/2 that of the conventional steel cord Z, which had a loose twist.

In addition, the steel cord of the present invention was coated with rubber and tested using a three-point pulley type fatigue tester.
The steel cord of the present invention has a fatigue life approximately 1.2 to 1.5 times longer than conventional steel cord.

Effects of the invention Since the steel cord of the invention has the above-mentioned structure, when it is used covered with a rubber material, each strand can be reliably covered with the rubber material, and the twisting is stable, making it resistant to fatigue. This improves the elasticity and reduces elongation under low loads, which greatly improves workability when working with rubber.

The above-mentioned workability is particularly important in the calendering process where the steel cord is made into a sheet together with rubber, in which the conventional lightly twisted steel cord shown in Fig. 5 elongates in the longitudinal direction due to a very low tensile force. If a sheet is formed using a rubber material as it is, the rubber will shrink when the tensile force is removed, causing wrinkles to form on the sheet, which will have a negative impact on workability and quality. The code eliminates the above drawbacks.

In this way, the workability in the manufacturing process of tires, belts, etc. is greatly improved, and the quality of the steel cords is significantly improved. This is a highly practical idea that can greatly improve workability in the process.

[Brief explanation of drawings]

Figure 1 A, B, C, and D are cross-sectional views showing one embodiment of the steel cord of the present invention, and Figure 2 A, B, C, and
D is a sectional view showing another embodiment of the present invention, FIG. 3 is a load elongation curve diagram, FIG. 4 A, B, FIG. 5 A, B,
FIGS. 6A and 6B are cross-sectional views showing different conventional steel cords. 1, 5... Steel cord, 2, 3, 4... Bare wire.

Claims (1)

[Scope of utility model registration request] In a single-layer twisted steel cord in which four or five wires having the same wire diameter are twisted in the same direction and at the same pitch, at least one of the two wires twisted almost in contact with each other is Arranged approximately in the center of the steel cord, and twisting the other two or three strands around it, with at least one of the strands almost touching either of the two strands, Moreover, the steel cord is constructed so that there is no closed space anywhere between the above-mentioned strands.