JPS61252385A - Steel cord - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the construction of a steel cord for reinforcing rubber such as automobile tires and conveyor belts by embedding the cord in the rubber.

(Prior art and its problems) The structure of the conventional steel cord is the 4th rji! 6th from J
The configuration is as shown in the figure, and the configuration shown in Figure 4 is for general K.
IX4. It is called IX5, and is made by twisting four or five strands of the same diameter at a time in the same direction and at the same pitch.

Fig. 5 This is a structure called 2+2, in which two groups of parallel strands and two other strands of the same wire diameter are twisted together (for example, Japanese Patent Laid-Open No. 193253/1983). Figure 6 shows a configuration also called 2+7, in which the core strand is made up of two strands, and on top of it, seven side strands of the same diameter are twisted in the same direction at different pitches. (For example, Japanese Utility Model Publication No. 57-9439) 3゜By the way, the criteria for determining the structure of conventional steel cords vary depending on the type of tires and conveyors used and the location of use, and the breaking strength of steel cords and Flexibility is a big factor. For this reason, the diameter of the strands, the number of strands constituted, and the combination of these are almost determined, and for 14 or 5 strands, the configuration shown in Figure 4 is adopted, and one with slightly greater breaking strength is required. After a while, the configuration shown in FIG. 6 was adopted.

However, in the configuration shown in Figure 4, the strands are in close contact with each other, creating a space C in the center, and the rubber does not penetrate into the steel cord, resulting in insufficient adhesion, which prevents moisture from entering from the outside. Recently, a problem has arisen in which rust occurs in the wires and the strength and fatigue resistance of the cord are greatly reduced. For this reason, a steel cord having the configuration shown in FIG. 5 was devised.

With this configuration, the infiltration of rubber is greatly improved, and there is no longer a space inside the steel cord where rubber cannot enter. However, in this configuration, the structure is unstable, which causes difficult problems in manufacturing and use, and new drawbacks have also occurred in the performance as a reinforcing material.

That is, when this steel cord is embedded in rubber and becomes a rubber reinforcing material, there is a problem in that its fatigue resistance is lower than that of other steel cords.

In addition, the steel cord with the configuration shown in Figure 6 is considered to be optimal for combining nine strands, but in order to improve rubber penetration, it is necessary to make the twist pitch of the core and sides different. 1. Therefore, there is a problem that two steps are required for manufacturing, resulting in poor production efficiency.

The present invention solves these problems and provides a steel cord that is easy to manufacture, has good rubber penetration, maintains other mechanical properties sufficiently, and can be used under almost the same conditions as ordinary steel cord. This is what I am trying to do.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration. That is, the steel cord of the present invention is composed of two layers, an inner layer and an outer layer, the inner layer consists of two strands, and the outer layer consists of 2 to 7 strands, and these strands are approximately the same line. The inner layer 1 and the outer layer are both twisted in the same direction. The twist pitch P1 of the outer layer is constant in the longitudinal direction, and the twist pitch of the inner layer is a variable twist pitch in the longitudinal direction, and has a short twist pitch P20 part and a long twist pitch Ps part, and the twist pitch of the inner layer is a variable twist pitch. Average twist pitch P in the longitudinal direction
4 is approximately the same as the twist pitch P1 of the outer layer.

In addition, the twist pitch of the outer layer is 21 to 20, the short twist pitch of the inner layer is Pz = 0.5Pz to O,g P 1, and the long twist pitch of the inner layer is P b = 1.2 P z , t5 P
In z, the interval P between the short twist pitch Pg and the long twist pitch Ps is
5Pz~30P! It is configured to be.

Here, since the steel cord of the present invention is composed of two layers, an inner layer and an outer layer, even if the inner layer is composed of two layers and the outer layer is composed of two layers, the outer layer and the inner layer are not twisted together. The outer layer is constantly twisted around the outer periphery of the inner layer. Next, the twist pitch of the inner layer is a variable twist pitch, which periodically repeats a short twist pitch and a long twist pitch, but the short twist pitch P2 mentioned above is the shortest twist pitch in one cycle. Similarly, the long twist pitch P3 means the longest twist pitch in one cycle. Therefore, 1 These twist pitches Pz
, Ps is not maintained stably for too long, and the twist angle α2 corresponding to the twist pitch P2°PSK is increased only at extremely short intervals.
．． It may also show α5. Even in such a case, the twist angle α2. The twist pitch of the part indicated by αs2 is P2. It shall be expressed as PR.

The twist pitch Pzd of the outer layer is 2+ for this type of steel hood.
The suitable value for wires composed of 2 to 2+7 strands is the above-mentioned range of 7 to 20111. If the wire is shorter than 17, the reduction in twisting will be large and the strength of the steel cord will be significantly reduced. If it is larger than the curvature, the twist becomes unstable. Furthermore, the values of the other intervals P1, short twist pitch P8, and long twist pitch P3 were selected based on substantially the same idea as described above after repeating various experiments. Here, even if the values of short twist pitch P2 and long twist pitch P3 exceed the upper limit or lower limit of twist pitch P1 of the outer layer by a wide range, it is acceptable because the twist pitch of the inner layer fluctuates. Even if Ps becomes a little longer and the twist becomes somewhat unstable, the outer layer can prevent the inner layer from coming apart.Even if the twist pitch Pz becomes a little shorter, if a tensile force is applied, the wire with the longer twist pitch This causes a phenomenon in which the twist returns to the original, and the loss of twist can be alleviated.

(Function) In the steel cord according to the present invention, the twist pitch of the inner layer and the twist pitch of the outer layer vary at each position, and since the inner layer is composed of two strands, there is a closed space between each strand. This does not occur, and when rubber is infiltrated, the rubber sufficiently infiltrates into the inside of the steel cord. Further, since each strand of the inner and outer layers and the layers are in contact with each other, even if a tensile load is applied to the steel cord, there is almost no elongation at a low back weight. Furthermore, since the value of the twisting pitch in the longitudinal direction of the inner layer is approximately the same as the twisting pitch of the outer layer when averaged, these inner and outer layers are can be produced simultaneously in one process with only slight improvements.

Embodiment An embodiment of the steel cord of the present invention is shown in FIGS. 1 and 2.

Two wires 1 of brass plated wire with the same wire diameter (for example, 0.25φ) are twisted at a short twist pitch P2 (71
) and the long twist pitch P3 (
The inner layer 2 is formed by having three strands 3 alternately twisted in the twisting direction S, and the outer layer 4 is formed by having three strands 3 twisted in the twisting direction S and with a twisting pitch Pi (10mm). This constitutes the steel cord 5 of the present invention.

In addition, the short twist pitch P2 part and the long twist pitch Ps part of the inner layer occur continuously in the longitudinal direction of the steel cord as shown in FIG. 2, and the interval P (1
00■) appears alternately. Moreover, the average twist pitch P4 (10111) in the longitudinal direction of the inner layer is the twist pitch P4 (10111) of the outer layer.
Formed to be approximately the same as i (10 rin).

Further, the variable twist pitch of the inner layer can be changed stepwise or linearly.

Next, the case of manufacturing the steel cord of the present invention will be explained based on FIG. A false twisting roller 8 and a mirror plate 9 ft long are arranged in front of the test piece.

The strands 1 of the inner layer and the strands 3 of the outer layer are guided to the mirror plate 6. First, the strands 1 of the inner layer are passed through the collecting die 7 and wound around the false twisting rollers 8, and then the strands 3 of the outer layer and the inner layer are twisted. The wire is guided to the end plate 9, passed through the collecting die 10, wound around the false twisting roller 11, and sent to the main body of the wire twisting machine.

This steel cord is rotated by the main body of the wire stranding machine, and the winding rule 1 is installed on the internal cradle 13.
4.

By the way, the rotation of the false twisting roller 11 is driven by the drive source of the main body wire twisting machine and is a substantially constant rotation.

However, the rotation of the false twisting roller 8 is transmitted via the transmission 15 even though the driving source is the same. The rotation speed of the false twisting roller 8 is designed to be changed in accordance with the change in the twisting pitch of the inner layer of the present invention.

If a steel cord is manufactured by operating the wire twisting machine having the above configuration as described above, the steel cord of the present invention shown in FIG. 1 will be obtained.

(Effects of the Invention) Since the steel cord of the present invention has the above-described configuration, it has the following effects.

The production of steel cord is somewhat more complicated than the steel cord shown in Figure 4, but the 2+7 shown in Figure 6
It is not necessary to perform the manufacturing process t2 step as in the steel cord structure of 2015, and it can be produced in one step, so production efficiency is very high. Also, when winding the product, there is no phenomenon of large elongation at low loads. , the handling of the product is now the same as the previous 4th one, without the occurrence of reel punctures, etc.
It may be similar to the steel cord shown in FIGS.

Next, when using the steel cord as a reinforcing material by embedding it in rubber, etc., it is very easy to handle because it does not elongate under low loads. When embedding a steel cord in rubber, etc., cover the steel cord from both sides with a very thin rubber sheet to create a sheet of steel cord and rubber. As is known, elastic materials such as rubber elongate even under low loads, so the tension of the steel cord must be kept at an extremely low tension. Although there was a very difficult problem in the work, the steel cord of the present invention, like the steel cord shown in FIG. 4, can be worked without any worries in this respect.

Furthermore, when this steel cord is embedded in rubber and used as a rubber reinforcing material, it has excellent adhesion effects, especially when adhering to rubber, resulting in significantly better results than the conventional steel cord shown in Figure 4. shows.

The above features are listed below.

*However, the numbers are 100 based on the conventional 1 x 5 (shown in Figure 4), and are expressed as an index by comparing others. A larger number indicates a better result, and a smaller number indicates a worse result. ing.

By the way, the steel cord according to the present invention can be applied from a total of 2+2 to 2+7 with the same configuration,
All of these exhibit almost the characteristics described above,
This invention can replace a small number of conventional configurations, and has a great effect from the viewpoint of enriching technology.

[Brief explanation of the drawing]

Figure 1 shows one embodiment of the steel cord of the present invention, (a)
is a front view of a portion where the inner layer has a short twist pitch, (B) is a front view of a portion where the inner layer has a long twist pitch, (C) is a cross-sectional view, and Fig. 2 is a variation in the twist pitch of the inner layer of the steel cord of the present invention. 3 is a configuration diagram of a stranding machine for producing the steel cord of the present invention, FIGS. 4(a) and 4(b) are cross-sectional views of a conventional steel cord, and FIG. ) and Figure 6 (a)
(B) is a front view and a sectional view of a conventional steel cord, respectively. 1...Inner layer strand 2...Inner layer 3...Outer layer strand 4...Outer layer ζ-...Full 4+Furu 1+V 6.9...End plate 7.10...Collecting die 8.1
1...False twisting roller recognition...Twiring machine body 13...Cradle 14...
・Take-up reel 15...Transmission ＼, J(RO) (IX) No. 2111

Claims (2)

[Claims] (1) In a steel cord in which the inner layer is composed of two strands of wire and the outer layer is composed of 2 to 7 strands, the strands have approximately the same wire diameter, and both the inner and outer layers are twisted in the same direction. , the twist pitch P_1 of the outer layer is constant in the longitudinal direction, and the twist pitch of the inner layer is such that parts with a short twist pitch P_2 and parts with a long twist pitch P_3 appear alternately in the longitudinal direction, and the twist pitch of the inner layer in the longitudinal direction is A steel cord characterized in that an average twist pitch P_4 is substantially the same as a twist pitch P_1 of the outer layer. (2) The twist pitch P_1 of the outer layer is 7 mm to 20 mm, and the short twist pitch P_2 of the inner layer is 0.5P_1 to 0.8P_1.
, inner layer long twist pitch P_3=1.2P_1~1.5P
_1, and the distance P between the short twist pitch P_2 and the long twist pitch P_3 of the inner layer is P=5P_1 to 30P_1.