JPH04343776A - Steel cord for tire - Google Patents

Abstract

PURPOSE:To provide the subject cord having a small elongation, a small cross section in the cord and spaces capable of being filled with a rubber, by twisting one or two from three to five element wires as core wires with the remaining side wires in a specific state. CONSTITUTION:One or two from three to five element wires as core wires 2 are twisted with the remaining as side wires 3 in a state in which the central axial lines of the core wires and side wires are decentered from the axial line of the cord, respectively. The spiral degree of the side wires is enlarged compared with that of the core wires. The adjacent element wires of the core wires and the side wires are brought into contact with each other in a triangular shape cross section, thereby providing a cord in which spaces are left between bending parts 4 and the element wires and in which the core wires and the side wires and further the respective element wires of the side wires are neighbored in mutually tight states.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel cord embedded in a tire.

0002

[Prior Art] Conventional steel cords for tires include closed cords and open cords.
In FIG. 6a), the rubber does not penetrate into the center of the cord, so a void is created in the center of the cord, that is, in the tire. This gap has the problem of causing rust that occurs locally on the cord to spread throughout the tire.

In the latter case (FIG. 6b), the stranded wires are manufactured with excessive patterning, so the void area in the center of the cord is large, and the amount of intruding rubber to fill this large void area is large. A lot of rubber is required, and in some cases, the rubber may not be able to fit completely, and the twisting tends to become unstable. In addition, the large elongation under low load makes it difficult to use the cord when burying the tire.

However, the problem of the large void area at the center of the cord can be minimized by making the adjacent strands adjoin each other in a triangular diametrical cross-section. can be solved by making one of the wires straight. However, in a cord having such a configuration, there is no gap between the strands, so the gap at the center of the cord is not filled with rubber even though it has the smallest area. Therefore, a configuration in which a bent part is formed in some of the strands along the line direction and a gap remains between this bent part and the adjacent strand part is shown in Fig. 6(c).
This is the prototype shown in . When such a prototype was tested, good results were obtained in which the rubber filled the gap in the center of the cord, eliminating concerns about rust and elongation. However, in some cords, the wires were broken, and when the broken wires were examined, they were found to be straight wires. It is presumed that this wire breakage problem is due to the tensile load being concentrated on the straight wire. Although various other steel cords for tires have been proposed, none of them have solved all of the problems of rust, elongation under low loads, and wire breakage.

[0005]

[Problems to be solved by the invention] The cross-sectional area of the voids in the cord is large, the elongation is large and the twisting is unstable, and the tensile load is concentrated on some of the strands.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention has a cross-sectional structure that minimizes the cross-sectional area of voids in the cord even though it is a 4 to 5 twisted cord, and also has a cross-sectional structure that minimizes the cross-sectional area of the voids in the cord. The core line side and The degree of the helical state on the side line side is varied, and a bent portion is repeatedly provided to one or more of the constituent wires along the helical direction.

Specifically, it consists of a core wire consisting of one or two strands out of three to five twisted strands and a side line consisting of the remaining number of strands, and the core wire is centered at the center of the concentric wire. The axis maintains a small helical state in the longitudinal direction eccentric from the cord axis, and the side wires twisted spirally around this core wire are arranged in a longitudinal direction in which the center axis of each strand of the same side wire is eccentric from the cord axis by more than the eccentricity difference of the core wires. The core wire and the side wires maintain a large helical state, the wires in the core wire and the side wires repeatedly have bent portions along the helical direction, and the wires of the core wire and the side wires are adjacent to each other with a triangular diameter cross section, and the bent portions and the wire portions are adjacent to each other. The core wire, the side wire, and each strand of the side wire are closely adjacent to each other, leaving a gap between the core wire and the side wire.

[0008] Also, the core wire is composed of a core wire made of one or two of the twisted strands of three to five strands and a side wire made of the remaining number of strands, and the core wire has a central axis line of the concentric wire that is a cord. A small helical state is maintained in the longitudinal direction eccentric from the axis, and the side wire twisted spirally around this core wire is a large spiral in the longitudinal direction in which the center axis of each strand of the same side wire is eccentric from the cord axis by more than the eccentricity difference of the core wire. state, the strands in the side wire repeatedly have bent portions along the helical direction, the core wire and the strands of the side wire are adjacent to each other with a triangular diameter cross section, and there is a gap between the adjacent bent portions and the strand portion. The core wire, the side wire, and each of the strands of the side wire are closely adjacent to each other, leaving .

[0009] Furthermore, the core wire is composed of a core wire made of one or two of the 3 to 5 twisted strands and a side wire made of the remaining number of strands, and the core wire has a central axis line of the concentric wire that is the cord. A small helical state is maintained in the longitudinal direction eccentric from the axis, and the side wire twisted spirally around this core wire is a large spiral in the longitudinal direction in which the center axis of each strand of the same side wire is eccentric from the cord axis by more than the eccentricity difference of the core wire. The state is maintained, the strands in the core wire repeatedly have bent portions along the helical direction, the strands of the core wire and the side wires are adjacent to each other with a triangular diameter cross section, and there is a gap between the adjacent bent portions and the strand portions. The core wire, the side wire, and each of the strands of the side wire are closely adjacent to each other, leaving .

Further, in the present invention, the eccentricity difference between the core wire and the side wire with respect to the cord axis is appropriately selected in consideration of the correlation between wire breakage and elongation. Further, the eccentricity difference of the side wire is set to exceed the eccentricity difference in the core wire, and when the same side wire has a plurality of strands, the eccentricity difference of each strand is inevitably selected depending on the cord cross-sectional configuration. In addition, the pitch of the bent portion is 1 of the wire diameter.
0 to 50 times, and the wire diameter is 0.15 to 0.
The diameter is 38 mm, and both are appropriately selected in consideration of the relationship with the tire. Furthermore, when there are two or more strands of wire having bent portions, the bent portions of each strand may be aligned with or deviated from each other in the cord axis direction.

[0011]

[Operation] The central axes of the core wire and side wires are eccentric with respect to the cord axis, the degree of helical state on the core wire side and the side wire side is different in size, and the strands of the core wire and side wires are adjacent to each other with a triangular diameter cross section. , and each strand of the core wire and the side wire is closely adjacent to each other, leaving a gap between the adjacent bent part and the strand part, and the core wire, the side wire, and each strand of the side wire are closely adjacent to each other. Although the number of twisted wires is 3 to 5, the twisted cross-sectional structure minimizes the cross-sectional area of the void in the cord and distributes the tensile load to all the wires. The amount of infiltrated rubber required to fill the cord is small, and there is no need to leave a large gap between the bent part and the strand part where the rubber infiltrates, and the void in the cord is completely filled with rubber through the small gap. be able to.

[0012] As a result, there are no voids that would cause rust, and the twisting is stable, the load is not concentrated on a particular strand, there is no wire breakage, and elongation under low loads is small.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the figure, 1 is a steel cord, and this steel cord consists of a core wire 2 consisting of one or two strands out of three to five twisted strands, and a side wire 3 consisting of the remaining number of strands. , the core wire 2 maintains a small helical state in the longitudinal direction in which the center axis a of the concentric wire 2 is eccentric from the cord axis o, and the side wires 3 twisted around the core wire 2 in a spiral shape are aligned with the center axis b of each strand of the same side wire 3. maintains a large helical state in the longitudinal direction eccentric from the cord axis o by more than the eccentricity difference of the core wire 2, and the strands of the core wire 2 and the side wires 3 are adjacent to each other in a triangular diametric cross section and are closely adjacent to each other. A gap is formed between a bent portion 4 repeatedly formed in the wire direction of any wire in the core wire 2 and side wire 3 and a portion of the wire adjacent to the bent portion. 5 is formed.

In the steel cord 1 illustrated in FIGS. 1 and 2, the core wire 2 consisting of one strand 2a maintains a small helical state in the longitudinal direction with the central axis a of the strand appropriately eccentric from the cord axis o. The side wire 3, which has bent portions 4 repeatedly along the wire direction and is spirally twisted around the core wire 2, has a central axis b of each strand in a longitudinal direction eccentric from the cord axis o by more than the eccentricity difference of the core wire 2. It consists of four strands 3a to 3d that maintain a large helical state, and the second and third middle two strands 3b and 3c have repeated bends 4 along the line direction. . And core line 2 and side line 3
The adjacent strands 2a and 3a to 3d are adjacent to each other in a triangular diameter cross section, leaving a gap 5 between the adjacent bent portions 4 and the strands, and the core wire 2 and the side wire 3 as well as the side wire 3. The individual wires are closely adjacent to each other. In addition, the three gaps s formed between the core wire 2 and the side wire 3 are composed of the strand 2a on the side of the core wire 2 where the bent part 4 is located, and the two middle strands 3b and 3c of the side wire 3. The gap 5 is surrounded by a group of wires having a triangular diameter cross section, and a gap 5 communicates with each gap s.

[0015] As a result, two or more gaps 5 communicate with each of the three gaps s, and each gap s is efficiently and sufficiently filled with rubber from two or more gaps 5 at the same time.

In this embodiment, the side wire 3 is composed of two wires, one with the bent portion 4 and one without, but it is also possible to use one wire and three wires for the other. Moreover, regarding the arrangement, the wires having the bent portions 4 may be used as the ends, or the wires having no bent portions 4 may be alternated.

In the steel cord 1 illustrated in FIG.
The core wire 2 made of real wires 2a maintains a small helical state in the longitudinal direction with the central axis a of the wire being appropriately eccentric from the cord axis o, and the side wires 3 twisted around the core wire 2 in a spiral shape are of each wire. It consists of four strands 3a to 3d which maintain a large helical state in the longitudinal direction whose central axis b is eccentric from the cord axis o by more than the eccentricity difference of the core wire 2, and the first and third two strands among them are The lines 3a and 3c have repeated bends 4 along the helical direction. The core wire 2 and the side wire 3 are arranged so that the adjacent wires 2a and 3a to 3d are adjacent to each other in a triangular diametrical cross section, leaving a gap 5 between the adjacent bent portion 4 and the wire portion. and the side wire 3, and the respective strands of the side wire 3 are closely adjacent to each other. In addition, there are three spaces s formed between the core wire 2 and the side wire 3.
A gap 5 is connected to each.

In this embodiment, the side line 3 is connected to the bent portion 4.
Although the structure is composed of two strands having a bending part 4 and two strands having no bending part 4, the composition ratio and arrangement thereof are arbitrary. be.

In the steel cord 1 illustrated in FIG.
A core wire 2 made of a real wire 2a maintains a small helical state in the longitudinal direction where the central axis a of the wire is appropriately eccentric from the cord axis o, and repeatedly has bent portions 4 along the wire direction,
The side wires 3 twisted spirally around the core wire 2 are four wires 3 that maintain a large helical state in the longitudinal direction, with the center axis b of each wire being eccentric from the cord axis o by more than the eccentricity difference of the core wire 2.
It consists of a to 3d. The core wire 2 and the side wire 3 are arranged so that the adjacent wires 2a and 3a to 3d are adjacent to each other in a triangular diametrical cross section, leaving a gap 5 between the adjacent bent portion 4 and the wire portion. and the side wire 3, and the respective strands of the side wire 3 are closely adjacent to each other. Further, gaps 5 communicate with the three gaps s formed between the core wire 2 and the side wires 3, respectively.

Furthermore, in the embodiment illustrated in FIG. 4, the side line 3
If the number of strands in the structure is three, the steel cord 1 can be made up of four strands.

In the steel cord 1 illustrated in FIG.
A core wire 2 consisting of real wires 2a and 2b maintains a small helical state in the longitudinal direction with the center axis a of the wire being appropriately eccentric from the cord axis o, and the side wires 3 twisted around this core wire 2 in a spiral shape are The center axis b of the wire is from the cord axis o to the core wire 2.
It consists of two strands 3a, 3b that maintain a large helical state in the longitudinal direction with eccentricity greater than the eccentricity difference, and the two strands 3a, 3b repeatedly have bent portions 4 along the helical direction. . Then, the core wire 2 and the side wire 3 have adjacent wires 2a, 2b and 3a, 3b adjacent to each other in a triangular diameter cross section, leaving a gap 5 between the adjacent bent portion 4 and the wire portion, The core wire 2, the side wire 3, and the respective strands of the side wire 3 are closely adjacent to each other. In addition, there are two spaces s formed between the core wire 2 and the side wire 3.
is surrounded by a group of wires having a triangular diameter cross section, consisting of the wire 2a on the core wire 2 side and the two wires 3a, 3b with the bent portion 4 on the side wire 3, and The gaps 5 communicate with each other.

[0022]Thereby, two or more gaps 5 communicate with each of the two gaps s, and each gap s is efficiently and sufficiently filled with rubber from the two or more gaps 5 at the same time.

The gaps 5 in each of the embodiments described above communicate with the gaps s of the cord 1, and the gaps s are filled with rubber infiltrating through each gap 5.

Table 1 shows a comparison between the cord of the present invention and the conventional cord in terms of low load elongation (between 0 and 5 kg) and rubber infiltration into voids. The number of twists and diameter of the cord is 5 x 0.25, and the items marked with * in the table are the ratio to the closed cord, and d in the pitch of the bent section indicates the wire diameter (mm). .

[0025]

[Table 1]

As is clear from Table 1, the product of the present invention showed a low elongation rate at low load close to that of the closed cord, and the rubber penetration was 100%, the same as that of the open cord. On the other hand, we confirmed that both closed code and open code have advantages and disadvantages.

[0027]

Effects of the Invention: Although the cord has low initial elongation and stable twisting, it is possible to fill the voids in the minimum cross-sectional area of the cord with rubber.

[0028] Since the elongation rate is small and the twisting is stable, workability when using the cord when embedding the tire is good. Since the gap is filled with rubber, the gap is substantially eliminated when the tire is embedded in the tire, and there is no problem of rust formation or inconvenience caused by rust. Furthermore, since the tensile load is applied to all the wires in a distributed manner, there is no possibility that some wires will break.

[Brief explanation of drawings]

FIG. 1 is a partial front view showing an example of the steel cord of the present invention.

[Figure 2] (A) is an enlarged sectional view taken along line A-A in Figure 1, (B)
1 is an enlarged sectional view taken along the line BB in FIG. 1, (C) is an enlarged sectional view taken along the line CC in FIG. 1, and (D) is an enlarged sectional view taken along the line DD in FIG.

FIG. 3 is an enlarged sectional view showing another embodiment of the present invention.

FIG. 4 is an enlarged sectional view showing another embodiment of the present invention.

FIG. 5 is an enlarged sectional view showing another embodiment of the present invention.

FIG. 6 (A) is an enlarged sectional view showing a conventional closed cord, (B) is an enlarged sectional view showing a conventional open cord, and (C) is an enlarged sectional view showing a prototype.

[Explanation of symbols]

1 steel cord
2 Core wires 2a, 2b Core wire strands
3 Side wires 3a to 3d Element wires of side wires
4 Bent part 5 Gap
s Gap o Cord axis
a, b Central axis of the wire

Claims (3)

[Claims] Claim 1: Consisting of a core wire consisting of one or two strands out of three to five twisted strands, and a side line consisting of the remaining number of strands, the core wire has a central axis line of the concentric wire that is a cord. A small helical state is maintained in the longitudinal direction eccentric from the axis, and the side wire twisted spirally around this core wire is a large spiral in the longitudinal direction in which the center axis of each strand of the same side wire is eccentric from the cord axis by more than the eccentricity difference of the core wire. The state is maintained, the strands of the core wire and the side wires repeatedly have bent portions along the helical direction, the strands of the core wire and the side wires are adjacent to each other with a triangular diameter cross section, and between the adjacent bent portions and the strand portions. A steel cord for a tire, characterized in that the core wire, the side wires, and each of the strands of the side wires are closely adjacent to each other, leaving a gap. Claim 2: Consisting of a core wire consisting of one or two strands out of three to five twisted strands, and a side line consisting of the remaining number of strands, the core wire has a central axis line of the concentric wire that is a cord. A small helical state is maintained in the longitudinal direction eccentric from the axis, and the side wire twisted spirally around this core wire is a large spiral in the longitudinal direction in which the center axis of each strand of the same side wire is eccentric from the cord axis by more than the eccentricity difference of the core wire. state, the strands in the side wire repeatedly have bent portions along the helical direction, the core wire and the strands of the side wire are adjacent to each other with a triangular diameter cross section, and there is a gap between the adjacent bent portions and the strand portion. A steel cord for a tire, characterized in that the core wire, the side wires, and each of the strands of the side wires are closely adjacent to each other. Claim 3: The core wire consists of a core wire consisting of one or two strands out of 3 to 5 twisted strands, and a side line consisting of the remaining number of strands, and the core wire has a central axis line of the concentric wire that is a cord. A small helical state is maintained in the longitudinal direction eccentric from the axis, and the side wire twisted spirally around this core wire is a large spiral in the longitudinal direction in which the center axis of each strand of the same side wire is eccentric from the cord axis by more than the eccentricity difference of the core wire. The state is maintained, the strands in the core wire repeatedly have bent portions along the helical direction, the strands of the core wire and the side wires are adjacent to each other with a triangular diameter cross section, and there is a gap between the adjacent bent portions and the strand portions. A steel cord for a tire, characterized in that the core wire, the side wires, and each of the strands of the side wires are closely adjacent to each other.