JPH10298880A - Steel cord and tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a steel cord having a simple structure and capable of assuring a sufficiently stable rubber penetrating property, also for which twisting process is sufficiently performed by only once and production cost thereof is also low. SOLUTION: This steel cord is a steel cord having 2-layered structure obtained by arranging three core wires 1a at the core part 1 and also 8-9 side wires 2a around the core, and twisting them simultaneously in a same direction in a same pitch. Each of the core wires 1a and the side wires 2a has small continuous small wavy kinks 200 different from the wavy kinks 100 caused by the twisting one or more wires and these wires are twisted loosely so as to have gaps S among the wires.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord used for reinforcing rubber products such as vehicle tires and conveyor belts, and a vehicle radial tire using the same.

[0002]

2. Description of the Related Art Conventionally, as a reinforcing member for a radial tire for trucks and buses, a steel cord having a two-layer twist or a multi-layer twist as shown in FIG. 1 or FIG. 2 has been used. These steel cords are required to have high strength and high durability as a reinforcing material, and also to have high corrosion resistance in a tire. In addition, simplification of the structure of the steel cord is required for cost reduction.

[0003] However, the conventional two-layer or three-layer steel cord has a two-step process in which the core A is tightly twisted using the strand as a strand and the side B is tightly twisted on the outer periphery thereof. In the latter case, a total of three steps of tightly twisting the outermost layer side C are required, which has a disadvantage of increasing the manufacturing cost. Also, in the cord structure of the prior art, as shown in FIGS. 1 and 2, the center of the core A is closed by three strands, so that in the vulcanization step of tire manufacturing, the rubber is coated with the core A. It does not penetrate to the center and is hollow. Therefore, a small amount of water contained in the tire and water entering from scratches such as metal chips and stones travel through the hollow portion in the still cord, and
Rust is generated and the life of the tire is shortened.

[0004] In order to solve this problem, the present applicant has
In JP-A-6-10281, a 1 × n structure in which eight or more strands are twisted in multiple layers, or a large number of side strands are twisted around a strand in which three strands are twisted. In the 1 × 3 + n structure, there has been proposed a structure in which a gap is intentionally provided between the strands of the core strand or between the strands of the side strand, and the cord section has a flat shape.

[0005] According to this prior art, the gap between the strands of the core strand and the gap between the strands of the side strand each have a gap, so that the rubber intrudes from the gap between the side strands during vulcanization after tire molding. Further, the rubber enters the inside from the gap between the strands of the core strand, and the center of the core strand is easily filled with the rubber. However, in this structure, when closely examined, there are many contact portions between the core strand strand and the side strand strand, and tension is applied to the steel cord particularly during vulcanization after tire formation,
As shown in FIGS. 3A and 3B, the number of contact portions C increases,
As a result, there may be a portion where the rubber cannot penetrate into the inside of the cord, and for this reason, it has not been sufficient yet to obtain stable rubber permeability.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made by research to solve the above-mentioned problems, and its object is to provide a simple structure and sufficiently stable rubber permeability. Another object of the present invention is to provide a steel cord which can be obtained by a single twisting process and has a low production cost. Another object of the present invention is to provide a tire having good corrosion resistance and a long life.

[0007]

In order to achieve the above-mentioned object, the present invention comprises three core strands arranged on a core, and 8 core strands around the core strand.
In a two-layer steel cord in which ~ 9 side strands are arranged and twisted at the same pitch in the same direction at the same time, one or more of the core strands and the side strands are each twisted by twisting. In addition, it has a configuration in which continuous small waves are smaller than the waves, and the wires are loosely twisted so as to have a gap between the wires (claim 1). Further, in addition to the above configuration, the present invention is configured such that the cord cross section has a flat shape (Claim 2). According to the present invention, there is provided an automobile tire in which one of the two types of steel cord is used for at least a part of a belt or a carcass.

[0008] The continuous wavelet habit may be a spiral wave or a planar wave before twisting. Further, a wave intermediate between the two may be used. In addition,
Basically, the diameters of the wires are basically the same, but in some cases, the wires may be configured by combining wires having different diameters.

[0009]

According to the first aspect of the present invention, since the core element wire and the side element wire have an open two-layer structure in which they are loosely twisted, a gap is formed between each element wire. In addition, with a simple open structure, if tension is applied to the steel cord during rubber vulcanization,
Although the gap between the strands disappears or is significantly reduced, in claim 1 of the present invention, since at least one of the core strands 1a has the continuous wavelet habit 100, although there is only a partial contact, Most of the core wires 1a are not in contact with each other.
Further, since at least one of the side strands 2a also has the continuous wavelet habit 200, although there is only a partial contact, most of the side strands are not in contact with each other. Moreover, one or more continuous strands 100, 20 of one or more core strands 1a and one or more side strands 2a
With 0, a gap is reliably formed between the core element wire 1a and the side element wire 2a. For this reason, even if tension is applied to the steel cord at the time of rubber vulcanization, the continuous ripples 100, 100
With 200, the gap s between the strands can be reliably held, and stable rubber permeability can be obtained. Further, since all the wires can be manufactured by twisting them at the same time, a single process is sufficient and the manufacturing cost can be reduced. According to the second aspect, since the entire cord has a flat cross-sectional shape, the stability of the shape is good even if the cord is loosely twisted, the cord is unlikely to be untwisted even when tension is applied, and the gap between the strands is reduced. A feature that is difficult to be reduced can be exhibited.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 4 to 7 show one embodiment of the steel cord according to the present invention. 1 is a core part, 2 is a side part surrounding the core part 1, and the core part 1 is composed of three strands 1a. The side part 2 is composed of eight strands 2a. The strands 1a and 2a are generally provided with a coating of good adhesion to rubber such as brass on the surface of a high carbon steel wire. The three strands 1a constituting the core 1 and the eight strands 2a constituting the side part 2 are arranged as described above, and in this state, they are collectively loosened simultaneously in the same direction at the same twist pitch. Although it is a bunched cord having a 1 × 11 structure, it has a 3 + 8 shape while being twisted loosely as described above, so that a gap s is formed between the side wires 2a. Is formed.

Furthermore, in the present invention, at least one, preferably two or more of the three strands 1a constituting the core 1 are separated from the wavy formed by twisting.
It has a continuous wavelet habit 100. Further, at least one or more of the eight strands 2a constituting the side part 2 also have a continuous small wavy pattern 200, apart from the wavy pattern formed by twisting. In this embodiment, all of the three core strands 1a have a continuous wavelet 100, and four of the side wires 2a have a continuous wavelet 200, and these continuous wavelet 200 are provided. The side strands 2a are arranged alternately and twisted. The continuous wavelet habit 10
0, 200 is a predetermined range in which the pitch length p is smaller than the pitch length P of the twisting of the cords, as shown in FIG. Has become. This predetermined range is set so that the wavy processing is not too tight and the fatigue resistance of the steel cord is not impaired, and that when the tension is applied to the steel cord, the wave is stretched and the gap forming function is not lost. It is set appropriately. The height h of the continuous wave habit 100 of the core element wire 1a is within a predetermined range smaller than the spiral wave height H of the core strand, and the height h of the continuous wave wavy 200 of the side element wire 2a is The predetermined range is smaller than the spiral wave height H of the partial twist. These predetermined ranges are appropriately set so that the gap between the strands is sufficient to obtain the rubber penetration, and the core 1 and the side 2 do not lose their shape and the cord uniformity does not deteriorate. The pitch p between the continuous wave habit 100 of the core strand 1a and the continuous wave habit 200 of the side strand 2 is generally equal, but may be different depending on the case. Further, the continuous wavelet habits 100 and 200 may be helical in a state before twisting,
It may be a planar unevenness or an intermediate between the two.

The above-mentioned continuous wave habits 100 and 200 are preliminarily applied before the twisting, and are performed in advance.
The strands 1a and 2a to which 0 is added are loosely twisted together with the other strands 1a and 2a which do not have a continuous wavelet as the same pitch and the same twisting direction. Therefore,
As shown in FIG. 5, in addition to the fact that the strands 2 a are loosely twisted, a gap s is formed between adjacent strands. Gap s is surely formed, and this gap s
This allows the rubber to penetrate stably without penetrating the rubber into the inside of the cord. Also, the side 2
In this case, the gap s is reliably formed between the adjacent strands by the continuous wave hammer 200. Further, the wire 1a of the core 1 and the wire 2a of the side 2 are continuously waved.
Therefore, a gap s is also formed between the side strand 2a and the core strand 1a that face each other in the direction of the irregularities of the continuous wave, and the rubber can penetrate the interior through the gap s. When the continuous wavelet habits 100 and 200 are helical, the unevenness of the wave is in the 360-degree direction, so that a gap is reliably formed between the adjacent strands. Note that, unlike the present invention, when the core element wire 1a and the side element wire 2a are both tightly stranded cords, the core element wire is pressed tightly by the side element wires. Even if a continuous wavelet habit is applied, the gap forming effect due to the wavelet habit is reduced, but the present invention is not limited to the core wire 1a as described above.
This problem is avoided by loosely twisting the side strands 2a with the side strands 2a, and the gap forming effect of the continuous small wave hammer 100 of the core strands 1a and the gap forming effect of the side strands 2a can be sufficiently exhibited. . In the case where the continuous strands 200 are provided on the four strands of the side strands 2a as in the embodiment, and the strands 2a with the continuous strands are arranged alternately and twisted, the balance is obtained. As a result, since there is no occurrence of opening due to the gap being biased to one place, a uniform gap can be formed every other strand.

FIG. 7 shows a second embodiment of the present invention.
In this embodiment, at least one, preferably two or more (all three in the embodiment) continuous wave hammer 100 having a pitch and height different from the wavy caused by twisting the cords and having a smaller pitch than the wavy one. The three core strands 1a are arranged in the central area, and at least one strand is formed around the core 1 at a pitch different from that of the cord twist and smaller than that of the cord. Nine side strands 2a having a continuous wavelet 200 of height are arranged, and the core strands 1a and the side strands 2a are collectively loosely twisted in the same twisting direction and the same twisting pitch. Thereby, between core strands,
A gap s is formed between the side strands and between the core strand and the side strand. In this example, four continuous strands 200 are attached to the four side strands 2a. However, the present invention is not limited to this. Three continuous strands 200 may be attached to the three side strands 2a, and such strands may be arranged at every third strand. The other configuration is the same as that of the first embodiment, and the description is omitted.

What is shown is only a few examples of the present invention, and also includes attaching a continuous wave habit 200 to all of the side strands 2a. In each embodiment, the wire 1
Although a and 2a have the same diameter, they may have different combinations depending on the case. That is, for example, the diameter of the element wire 1a of the core 1 may be smaller or larger than the diameter of the element wire 2a of the side part 2, or the diameter of the core 1 3
One or two of the strands 1a may have a diameter different from that of the other strands. Alternatively, at least one of the strands 2a of the side part 2 may have a diameter different from that of the other strands.
However, in any case, the diameters of the wires 1a and 2a are equal to 0.
The value is preferably selected from the range of 17 to 0.36 mm, and if the diameter is less than 0.17 mm, the cord breaking load becomes too low. The reason why the upper limit is set to 0.36 mm is that the thickness exceeds this. This is because the breaking load and the rigidity of the cord are too high and are not suitable.

FIGS. 8 and 9 show a third embodiment and a fourth embodiment of the present invention. In these embodiments, the first
In addition to the configuration of the embodiment and the second embodiment, in the drawing, the steel cord is compressed from the vertical direction P, P, so that the cross section perpendicular to the cord longitudinal direction becomes a flat shape similar to an ellipse or an ellipse. I have. In this manner, by further loosely twisting the steel cord into a flat cross-sectional shape, the gap s is reliably formed because the side strands 2a and the core strands 1a are forcibly separated from each other. At the same time, the cord shape is stabilized, the twist of the cord does not easily return to the load in the longitudinal axis direction, and the contact between the wires can be reduced. The ratio of the short diameter D ₁ and the diameter D ₂ of the flat cross section (D ₁ / D ₂ oblateness) is generally 0.6 to 0.9 is suitable. When the flattening ratio is low (when the flattening ratio is close to 0.9), it is difficult to align the flat surfaces in one direction, and it is difficult to have a constant cross-sectional shape in the longitudinal direction, but when the flattening ratio is high (flattening ratio). Is closer to 0.6), the cross-sectional shape becomes one direction in the longitudinal direction. That is, the sectional shapes of FIGS. 8 and 9 are continuous in the cord longitudinal direction. The phrase that the cord cross section has a flat shape in the present invention includes such an aspect. In this case, the stability when the cords are aligned in parallel during tire production is good, and the cover rubber thickness is large. Has the advantage that it can be made thinner.

Next, a method of manufacturing a steel cord according to the present invention will be described. 3 core strands 1a and 8 to 9 side strands 2a
In the process of leading from the bobbin to the double-stranding machine and twisting it, the required number of the three core strands 1a and the required number of the side strands 2a are each set in a continuous wave form 100 , 200. It is continuous wavelet habit 10
If 0,200 is helical, 3-5
Use a rotating (revolution) corrugating device in which approximately this number of pins are arranged at an interval, pass through the wires, and do not use the rotating corrugating device for wires that do not have a continuous wavelet. I do. For example, when the continuous wave habit 100 is applied to all three core strands 2a, the respective core strands 2a
In the case where the rotation wave applicator is arranged on the movement path of a and the continuous wave wave 200 is applied to four of the side strands 2a, the rotation wave applicator is arranged only on those movement paths.

By such means, the spiral continuous ripples 100 and 200 are plastically worked on the core strand 1a and the side strand 2a. After that, all the core wires 1a and the side wires 2a
Is to pass through the pins of a downstream molding device in which three to five pins are attached in a zigzag manner to the substrate in the same manner as the rotary corrugating device. However, this molding device does not rotate on the wire movement path. The position is fixed. Continuous ripples 100, 200
And all the wires 1a,
2a is passed through this stamping device and is given a stamping that is suitably larger than in the case of compact cords. The strands thus shaped are then assembled through the end plate so that the three core strands 1a are located in the central region and the side strands 2a are located therearound. At this time, in the above example, the four side strands 2a to which the continuous wavelet
May be guided to the voice through the mirror plate so that every other strand 2a not subjected to the continuous wavelet habit 200 is placed alternately. Then, it is guided from the voice to the double twisting wire machine, whereby all the wires are collectively loosely twisted into a two-layer open cord. In this way, a bunched cord having a gap between the strands is obtained. Before winding the steel cord on a reel, the steel cord may be lightly compressed from a 180-degree symmetric position by a pair of rollers arranged on a path.
In the case where the continuous wave habit 100 of the core element wire 1a is formed into a plane wave form, a pair of gears whose teeth are meshed with each other is used as the corrugating device, and this is the same element wire as described above. It may be arranged in the movement path, and a wire to be subjected to continuous ripples may be passed between the pair of gears, whereby the wire is crimped in a zigzag manner by the meshing teeth.

FIG. 8 shows a radial tire to which a steel cord according to the present invention is applied, wherein 8 is a belt,
9 is a carcass. When the flatness of the steel cord according to the present invention is large, it is preferable that the long side of the belt 8 is arranged parallel to the tread surface and that the carcass 9 is arranged parallel to the center of the tire. Therefore, the thickness of the cover rubber can be reduced, which is effective in reducing the weight of the tire.

[0019]

According to the present invention described above, three core strands 1a are arranged at the core portion, and eight to nine side strands 2a are arranged around the core strands 1a, and are arranged at the same pitch in the same direction. In a two-layer steel cord that is simultaneously twisted, each of the core strands 1a and the side strands 2a has continuous ripples 100 and 200 that are smaller than the ripples separately from the ripples formed by twisting. Since the strands are loosely twisted so as to have a gap between the strands, a synergy between the loose twisting form and the continuous ripples 100 and 200 of the core strand 1a and the side strand 2a is provided. By the action, gaps can be reliably formed between the core strands, between the side strands, and between the core strands and the side strands.
a and side strands 2a are continuous ripples 100, 200, respectively.
Therefore, even when tension is applied to the cord and the cord section is tightened from a loose state, the appropriate gap can be reliably maintained by the continuous ripples 100 and 200, and thereby the rubber can be extended over the entire length of the cord. Can be completely permeable between the core strands, between the side strands, and between the core strands and the side strands. In addition, since the cord has a two-layer structure but has a single twist, an excellent effect that the manufacturing cost can be reduced can be obtained. Claim 2
According to, furthermore, since the cross section in the longitudinal direction of the cord has a flat shape, it is maintained in a stable shape while having a loose twisted structure, and the wires are kept together even when tension is applied during rubber vulcanization. It becomes difficult to approach. Therefore, due to the synergistic effect of the above-mentioned loosely twisted form and the continuous ripples 100 and 200 of the core strand 1a and the side strand 2a, uniform and stable rubber permeability over the entire length of the cord can be obtained. The effect is obtained. According to claim 3, since the steel cord of the present invention is used for reinforcing a belt or a carcass of a tire, the tire is excellent in corrosion resistance and can be a long-life tire. If they are arranged in parallel toward the center of the tire, the thickness of the cover rubber can be reduced, so that an excellent effect that the weight of the tire can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a conventional two-layer steel cord.

FIG. 2 is a sectional view of a conventional three-layer steel cord.

FIG. 3A is a cross-sectional view showing a conventional two-layer flat-structured steel cord under a tension load, and FIG. 3B is a cross-sectional view showing a state at another cross-sectional position.

FIG. 4 is an enlarged side view schematically showing the first embodiment of the steel cord according to the present invention.

FIG. 5 is a schematic sectional view of the first embodiment.

FIG. 6 is a side view schematically showing a wire taken out of the steel cord by disassembly in the first embodiment.

FIG. 7 is a sectional view schematically showing a second embodiment of the steel cord according to the present invention.

FIG. 8 is a sectional view schematically showing a third embodiment of the steel cord according to the present invention.

FIG. 9 is a sectional view schematically showing a fourth embodiment of the steel cord according to the present invention.

FIG. 10 is a partially cutaway perspective view showing an example of a radial tire to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core part 1a Core strand 2 Side part 2a Side strand 100 Continuous wavelet 200 Continuous wavelet s Gap

Claims (3)

[Claims] 1. A two-layer steel cord in which three core strands are arranged on a core portion and 8 to 9 side strands are arranged around the core strands and are simultaneously twisted at the same pitch in the same direction. ,
Each of the core strands and the side strands has a continuous small wavy shape smaller than the wavy shape, apart from the wavy shape by twisting, and loosens so that the strands have a gap between the strands. A steel cord characterized by being twisted. 2. The rubber cord for reinforcing rubber according to claim 1, wherein a cross section of the cord perpendicular to the longitudinal direction has a flat shape. 3. A radial tire for a vehicle, wherein the steel cord according to claim 1 or 2 is used for at least a part of a belt or a carcass.