JPH0274689A - High-elongation composite cord for reinforcing rubber and production hereof - Google Patents

Abstract

PURPOSE:To obtain a high-elongation steel cord having excellent elongation properties even after covering with rubber by adding a special organic fiber to ravines on the outside of adjacent strands and twisting the resultant. CONSTITUTION:Plural (5 in the figure) brass-gilt steel filaments 1 are twisted at a low pitch of twist to be formed into a strand 2 and the plural (3 in the figure) obtained strands 2 are twisted at a low pitch of twist to be formed into a steel cord 3. In that case, an organic fiber monofilament having a diameter (d1) capable of accommodation in a circumcircle of the cord 3 to be formed, i.e., a value satisfying formula I [h is defined by formula II (D0 is diameter of cord, i.e., diameter of circumcircle. D1 is diameter of strand. n is number of strands.)] and subjected to treatment for improvement of adhesion with rubber on the surface is added to ravines on the outside of adjacent strands 2 and the above-mentioned twisting is then carried out for formation of a cord.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention is a steel stranded wire, that is, a steel cord with a positive plating applied to the surface of a steel filament, which is used for reinforcing rubber composites such as automobile tires and conhair held. This invention relates to a steel cord that has excellent elongation properties after being composited with a steel cord, and a method for producing the same.

[Conventional technology]

Steel cord usually has a carbon content of 0.65 to 0.
The material is 85% high carbon steel wire (JIS G 3502 piano wire), the surface of which is plated with Cu-Zn binary or multi-component plus alloy, and wire-drawn to a diameter of 0.1 to 0.4 mm. Single-twisted, double-twisted, and multi-layered strands are widely used as reinforcing materials for tires, etc.

This includes what is called a high expansion code. This code is 2X4Xd, 3X3Xd, 3
It adopts a twisting configuration such as As you can see, it literally exhibits greater elongation under load than other general cords.

Furthermore, since these high elongation coats are made by twisting together only strands having the same characteristics, they are extremely easy to manufacture.

[Problem to be solved by the invention] Improve the elongation characteristics of the conventional high elongation cord before and after rubber coating by 3
An example of the code 3XO, 15 is shown in FIG.

In the case of this cord, it shows an elongation of about 1% under a tensile load of about 1 kgf before rubber coating, but after rubber coating it shows an elongation of about 1%.
When loaded, the elongation decreased to about 0.2%, and the elongation at break of the cord was 3 to 4%, compared to 5 to 6% before coating.
decreases to This remarkable change in elongation before and after rubber coating is observed in all high elongation cords, and therefore, conventional high elongation cords cause various problems in applications that require high elongation even after rubber coating. It was not suitable as it could cause harm.

The reason why the elongation decreases significantly after coating with rubber is that when the rubber coating is vulcanized, highly fluid rubber enters the gaps between the strands, solidifies after vulcanization, and causes the movement of the strands or steel filament under load. It is thought that the purpose is to restrain the people.

This invention aims to expand the uses of steel cord.
The first objective is to realize and provide a high elongation cord that exhibits excellent elongation properties even after being coated with rubber.

Next, the tension control device of conventional steel cord twisting machines uses a mechanical drum brake system or an electric dancer weight system. It does not follow well against external disturbances such as winding or poor reel winding shape. In addition, even in steady state, the supply tension is ±200 relative to the set value.
It is normal to weigh ~900g. However, when twisting only the same materials with the same properties, this is sufficient, but when twisting together steel strands and organic fiber monofilament, which have significantly different elongations under load, organic fiber monofilament Since the elongation changes depending on the magnitude of tension, it is difficult to obtain a composite cord that is homogeneous and has constant performance.

In addition, there are cases in which wire breakage occurs, which poses a problem in terms of productivity.

Therefore, the second object of the present invention is to provide a manufacturing method for obtaining a desired composite cord without causing these problems.
The purpose is to

[Means to solve the problem]

As a first invention to achieve the first object, this invention provides a high elongation cord in which plus-plated steel filaments are compositely twisted two or more times in the same direction at a small twisting pitch. The diameter that fits within the space created between the circumscribed circle, i.e., 0.3h≦d1≦0.5h where iDo (Do D+) A11l
(n2)l ”n h = D, +D, -(Do D+)k - (n-2)n An organic fiber that has a diameter that satisfies the formula and has improved adhesion to the rubber on the surface. Adopts a structure in which monofilaments are twisted together with adjacent strands.

10 in Figure 1 is 3 x 5 x d as a concrete example.
This is the code for (A). 1 is a plus plated steel filament, 2 is a strand made up of five strands of 1 twisted together, 3 is a steel cord made of three strands of 2 stranded, and 4 is a strand of strands that occur in three places between adjacent strands. Organic fiber monofilaments 4 are shown arranged in the valleys, preferably twisted together at the same time as the two strands are twisted, and this organic fiber monofilament 4 contacts both adjacent strands and closes the entrance of the gap between the strands 2. In this figure, Do attached to the circumscribed circle of the steel cord 3 represents the diameter of the steel cord 10, and Do attached to the circumscribed circle of the strand 2 represents the diameter of the strand, respectively. Further, the diameter d of the organic fiber monofilament 4 used in this cord 10 is 0.3h to 0.5h which satisfies the above formula, and the reason for this limitation will be explained later.

In addition, it can be said that it is extremely preferable for the number of filaments 1 constituting the strand 2 to be four or more so that the cross-sectional profile of the strand approaches a perfect circle for reasons described later.

In a second invention to achieve the above-mentioned first object, the above-mentioned idea is expanded to create a gap between the steel strands constituting the same high elongation cord, and further, the steel cord circumscribed circle is A structure is adopted in which organic fiber monofilaments of a size that can fit within the space created between the adjacent strands are twisted in contact with the adjacent strands. In this case, if the gap between adjacent strands is equal to or larger than the diameter of the organic fiber monofilament, the organic fiber monofilament will enter inside the layer core circle of the strand, making the effect of preventing rubber intrusion unstable.
It is recommended that both satisfy the following formula.

20 in Figure 2 is 3 x 5 x d as a concrete example.
This is the code for (B). This cord 20 differs from the cord 10 in FIG. 1 in that it is composed of strands whose circumscribed circles are in contact with each other, in that there is a gap between adjacent strands. Other technical means are the same as those in FIG.

Next, a manufacturing method for achieving the second object of the present invention includes twisting the steel strands and the machine fiber monofilament using a twisting machine that includes a supply tension control device.
Steel strand supply tension is T.

The tension is controlled so as to satisfy the following relationships: 1.57F≦T, ≦0.20Bs 0.018F≦T, ≦o, t58F.

This method is more effective if an AC servo mechanism is adopted as the supply tension control device to stably maintain the supply tension of the organic fiber monofilament at ±30 g/filament with respect to the set value.

(Function) In order to suppress the decline in cord elongation after rubber coating, the strands constituting the cord and the steel filaments constituting the strands should be prevented from forming gaps between adjacent strands or between adjacent filaments, so that they do not enter the inside of the coat. It is necessary to eliminate the intrusion of rubber.

However, since the steel filaments that make up the strands are tightly twisted together, even though there is almost no intrusion of rubber into the strands, the distance between the strands that make up the cord is 3X3Xd from the cord in Figure 3. As can be seen, a gap is created that opens the space at the center of the cord to the outside. The gap is particularly large when the strand consists of 2 to 4 filaments, creating a situation where the rubber A tends to flow into the space at the center of the cord. However, as the number of filaments per strand increases, the cross-section of the strand approaches a circle, so the gap gradually becomes smaller.Therefore, increasing the number of filaments per strand will result in less rubber filling the central space. It is effective in reducing the inflow.However, there is a limit to making the cross-sectional shape of the strand as close to a circle as possible with a single-strand structure, and there is also a way to make the cross-sectional shape of the strand as close to a circle as possible by twisting it in multiple layers, but this The gap between the strands cannot be completely eliminated because this method is impractical as it increases the production process and the twisting pitch.

However, in the composite cord of the present invention, the AT63i fiber monofilament seals this inevitable gap between the strands and prevents rubber from entering the center of the cord.

Also, if you try to fill the 11× gap between the strands without significantly changing the tensile properties of the cord, it would be impossible with steel filament-ζ because it would greatly affect the cutting load and elongation properties of the cord. Organic fiber monofilaments have extremely low strength and flexibility compared to steel cords, so they do not significantly change the tensile properties of the cords.

Here, the reason for limiting the monofilament diameter d1 of the RW fiber will be described. First, regarding the upper limit of the tonne, it is not preferable for the organic fiber monofilament to protrude outside the circumscribed circle of the steel cord indicated by 00 in FIG. When the wire goes outside, it is twisted together with the steel strands and rubbed against various guide rollers, causing scratches on the surface.
As a result, problems arise in that the adhesion to the rubber deteriorates, and sometimes the wire breaks, making it impossible to achieve the purpose of preventing rubber from entering the center of the cord. Therefore, the upper limit of d was selected to be the maximum value within which the organic fiber monofilament 4 is in contact with adjacent strands and within the circumscribed circle of the steel cord. In this case, d is determined by the formula (%). Since h described in the previous section corresponds to 2a+, the upper limit of d is 0.5h.

On the other hand, the lower limit of d is 0.6 times the upper limit, or
The limit was set to 0.3 hours.

In addition, considering the maintenance of tensile properties, the optimal material for the organic fiber monofilament is nylon, polyester, etc.

Claim (2) wherein a gap is created between adjacent strands, and the entrance of this gap is closed with an organic fiber monofilament.
The composite cord described in Figure 2 (FIG. 2) also prevents rubber from entering the center of the cord for the same reason as above. In addition, since this cord allows adjacent strands to compress the organic fiber monofilament and come closer to each other, it is effective in increasing elongation to a level equal to or greater than that of the composite cord with the structure shown in Figure 1.

Next, the manufacturing method of the present invention was completed as follows. In other words, there is a large difference in breaking load and elongation under load between steel strands and organic fiber monofilaments, so in order to combine the above-mentioned composite cords into one, it is necessary to consider the relationship between the supply tensions of the steel strands and organic fiber monofilaments and the respective tensions. It is important to properly define the curfew and control it with precision.

Therefore, the inventor conducted various studies and experiments, and found that if the tension of the organic fiber monofilament is not less than 0.667 compared to that of the steel strand, the monofilament will easily enter inside the core diameter of the steel strand, and it will not be possible to enter the inside of the cord. Helps prevent rubber from entering.

This is why the second condition was established, and the lower limit of the tension of the steel strand is T from the clonic force, ≧1.5TF.

On the other hand, the upper limit value of the steel strand tension was set at 0.20B because if it exceeds 20% of the breaking load (B,) of the strand, the wire is likely to break.

Furthermore, since organic fiber monofilaments have a large elongation under low load, they are easily twisted together in an elongated state. However, in such a composite cord, after the organic fiber monofilaments are twisted together, the organic fiber monofilaments shrink over time from the free end, creating a gap between the steel strands and the organic fiber monofilaments that allows the inflow of rubber. Therefore, based on the load-elongation curve of organic fibers, a supply tension is required that can suppress shrinkage due to contact resistance with the steel strands even if the organic fibers are once stretched and twisted. If this supply tension T is 0, no adhesion force with the steel strand can be obtained, which is disadvantageous in terms of preventing rubber from flowing into the inside of the cord. According to the experimental results, it was effective in filling the gap between the steel strand and the steel strand when the elongation before the twisting end was 1 to 2%. Therefore, the appropriate lower limit value of Tr is the value that causes 1% elongation. It was judged.

Further, the upper limit value of Tr was set to a value that would cause an elongation of 5%, since a uniform composite cord could not be obtained if the elongation exceeded 5%. The load that causes this 1 to 5% elongation is 1 to 15% of the breaking load of the organic fiber monofilament (0,018t to
0.158F).

By the way, the breaking load of an organic fiber monofilament is about 0.92 kg, for example, taking a nylon 6G monofilament having a diameter of 0.15++ m. When using this material to manufacture composite cords, the supply tension is 9
．． It is necessary to control within the range of 2g = 138g. In other words, if the median value is used as the tension standard, 73.6±64
．． A supply tension saw adjustment device that can keep the weight below 4g is required. When selecting a device, we considered that it would be able to handle organic fiber monofilament diameters up to 0.1 m, and decided to aim for tension variation of ±30 g. In order to achieve this control accuracy, we adopted an AC servo mechanism for the supply tension control device of the wire twisting machine. In addition to being capable of forward and reverse rotation, this mechanism has excellent responsiveness and can immediately respond to disturbances, reducing tension errors to ±
It can be controlled within the range of 25g. Therefore, according to the method of the present invention, the above-mentioned composite code can be manufactured with good chain reliability.

[Example 1] An organic fiber monofilament with an eave diameter of 0118 is twisted on the outside between the vJ contact strands of a 3 x 5 xo, 15 (A) high elongation cord composed of plus-plated steel filaments with a diameter of 0.15 mm, A composite cord 10 having the cross-sectional shape shown in FIG. 1 was obtained.

The organic fiber monofilament was made of polyester or nylon, and its surface was treated to improve its adhesion to rubber.

This surface treatment in the prototype code is R, F, L (resorcinol formalin latex) treatment.

Next, a tensile test was conducted to examine the characteristics of the prototype cord. The results are shown in FIG.

From this figure, the code of the present invention is 3 X 5 XO, 1
It can be clearly seen that the elongation is maintained sufficiently under low load after rubber coating compared to the conventional high elongation cord No. 5.

Although the twist pinch of the cords compared in Figure 7 is the same, the cord diameter of the cord of the present invention is slightly larger due to the influence of the organic monofilament (the gap between the strands is slightly wider), so the elongation when uncoated is It actually gets bigger.

[Example 2] Next to a high elongation cord of 3 x 5 Organic fiber monofilaments with diameters of 0 and 22 mm that fit within the circumscribed circle of the cord are twisted together on the outside between the matching strands to form a composite cord 2 with the cross-sectional shape shown in Fig. 2.
0 (code ■ in Table 1) was obtained.

In addition, in the same manner, cord 20 (coat [V in Table 1), which is a composite of 2×5 Xo, 15 (B) high elongation cord and organic fiber monofilament, and the coat obtained in Example 1 (coat [V A composite cord (Code I in Table 1) having a different number of strands and a filament diameter from that of Example 1 was also obtained.

Furthermore, for comparison, codes (11 to θ9) in Table 1, which do not meet the conditions of the present invention, were also prepared, and the appearance and performance of these codes were evaluated. The results are also shown in Table 1.

〔effect〕

As mentioned above, the high elongation cord of the present invention is made by twisting organic fiber monofilaments on the outside between adjacent strands to close the entrance to the space in the center of the cord, which prevents rubber from flowing into the center space. π is effectively prevented, the problem of restraint of the steel filament by the inflowing rubber is eliminated, and excellent elongation properties are maintained even after being coated with rubber, which can contribute to further expanding the use of high elongation cords.

Further, according to the method of the present invention, since the steel cords and the organic fiber monofilament are twisted while controlling the supply tension within a predetermined range, it is possible to produce a homogeneous composite coat with good reliability.

[Brief Description of the Drawings] Figures 1 and 2 are sectional views showing a specific example of the cord of the present invention, Figures 3 and 4 are sectional views showing an example of a conventional cord, and Figure 5 is a sectional view showing an example of a conventional cord. Figure 6 is a graph showing the elongation characteristics of the 3 x 3 Xo, 15 high elongation cord before and after rubber coating. It is a graph comparing the difference in elongation after rubber coating. 1...Plus plated steel filament, 2
...Strand, 3...Steelco 4...Organic fiber monofilament, 10
．． 20...High extension cord.

Claims (1)

[Scope of Claims] (1) Among steel cords constructed by twisting steel filaments plated on the surface, high elongation cords with a small twisting pitch and compound twisting in the same direction two or more times are adjacent to each other. A high elongation composite cord for rubber reinforcement, characterized in that organic fiber monofilaments having the diameter shown in the formula below and whose surfaces are bonded to rubber are twisted in contact with adjacent strands on the outside between the strands. . 0.3h≦d_1≦0.5h Here ▲Mathematical formulas, chemical formulas, tables, etc.▼ [d_1: Diameter of organic fiber monofilament D_0: Diameter of steel cord (circumscribed circle) D_1: Diameter of steel strand n: Diameter of steel strand Number of strands] (2) Among steel cords made by twisting steel filaments plated on the surface, there is a gap between each strand in a high elongation cord with a small twist pitch and compound twisting in the same direction two or more times. , and further comprising organic fiber monofilaments of a size that fit within the space created between the circumscribed circle of the steel cord and the adjacent strands, which are twisted together in contact between the adjacent strands. Extended compound code. (3) A claim that the relational expression between the gap between adjacent strands and the diameter of the organic fiber monofilament satisfies S≦0.85d_1 S: distance between adjacent strands with a gap d_1: diameter of the organic fiber monofilament The high elongation composite cord for rubber reinforcement described in item (2). (4) When the steel strand and organic fiber monofilament are twisted together using a twisting machine that includes a supply tension control device, the steel strand supply tension is T_F≦T_S.
/1.5 [T_S; Supply tension of steel strand T_F; Supply tension of organic fiber monofilament] Satisfies the following formula, and 1.5T_F≦T_S≦0.20B_S 0.01B_F≦T_F≦0.15B_F [B_S; Breaking load of steel strand B_F;
2. The method for manufacturing a high elongation composite cord for rubber reinforcement according to claim 1 or 2, characterized in that the tension is controlled so as to satisfy the following relationship: [Breaking load of organic fiber monofilament]. (5) The high elongation composite cord for rubber reinforcement according to claim (4), wherein the supply tension control device employs an AC servo mechanism to stably maintain the supply tension of the organic fiber monofilament at ±30 g/piece with respect to a set value. manufacturing method.