JPH04370283A - Steel cord - Google Patents

Abstract

PURPOSE:To provide a steel cord having suppressed fretting of the wires with each other to enable sure improvement of the fatigue resistance. CONSTITUTION:The objective steel cord having a 2+2 structure is produced by twisting two wires 1b, 1b around the outer circumference of two formed core wires 1a, 1a while applying excess forming of >100% to the twisting wires 1b, 1b.

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 rubber material such as a vehicle tire or a conveyor belt and used for reinforcing the rubber material.

0002

[Prior Art] As a steel cord embedded in the belt of tires of passenger cars and light trucks, two wires that are also drawn in parallel are placed around the outer periphery of two core wires that are drawn in parallel. 2+ twisted tightly with a pitch of
Two-structure and 2+3-structure structures are known.

[0003] The state of each longitudinal cross section (a to d) of a steel cord S with a 2+2 structure is shown in Fig. 5, where 1a and 1a are core wires, and 1b and 1b are tightly twisted around the outer periphery. It is a wire.

0004

However, in such a conventional steel cord S, as shown in FIG. line contact or point contact,
Therefore, when the cord S is buried in the belt part of a tire and used as a reinforcing material, each wire 1a, 1a, 1
Wires 1a, 1a,
There is a drawback that the fatigue resistance of 1b and 1b decreases, which shortens the life of the tire.

[0005] The present invention has been made with attention to these points, and its purpose is to provide a steel cord that can suppress mutual fretting of the wires and reliably improve its fatigue resistance. It is about providing.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention has N wires each having an excess of more than 100% on the outer periphery of two wires of a shaped core. The steel cords are shaped and twisted together to form a 2+N steel cord.

[0007]

[Operation] In such a configuration, each wire contacts each other only at partial points in the longitudinal direction of the steel cord based on the shaping applied to each wire, and is spaced apart from each other at most other points. Therefore, when this steel cord is buried in the rubber of a tire and the rubber is vulcanized, the outer periphery of each wire is filled with rubber due to the gaps. Therefore, fretting between the wires is reliably suppressed and fatigue resistance is greatly improved, and since the outer periphery of each wire is reliably covered with rubber, its corrosion resistance is also improved.

[0008]

[Examples] Examples of the present invention will be described below. FIG. 1 shows the state of each longitudinal cross section (a to d) of the steel cord S according to the first embodiment. This steel cord S
is constructed in a 2+2 structure in which a wire bundle B, which is made up of two core wires 1b, 1b, is twisted around the outer periphery of a wire bundle A, which is made up of two core wires 1a, 1a arranged in parallel. However, each wire 1a, 1a, 1b, 1b is given a predetermined shape in advance, and based on this shape,
In the core wires 1a, 1a, each other has a code S.
The wires contact each other only partially in the longitudinal direction, and remain separated from each other in most other locations, and the outer wire 1
Similarly, in wires b and 1b, the cords S contact each other only at partial locations in the longitudinal direction, and remain separated at most other locations, and furthermore, the core wires 1a and 1
The wires 1b, 1b on the outer periphery of the wires 1a, 1b are in contact with each other only at partial locations in the longitudinal direction of the cord S, and remain separated from each other at most other locations.

[0009] Such a steel cord S can be manufactured using a twisting device shown in FIG. 2, for example. To explain the structure of this twisting device, 10 is a rotor, guide rolls 11, 12, 13, 14 are provided on the central axis of rotation of this rotor 10, and bows 15, 16 are provided on the inner circumference of the rotor 10. and these guide rolls 11,1
2, 13, 14 and bows 15, 16 are adapted to rotate together with the rotor 10.

Inside the rotor 10 are provided wire bobbins 17 and 18 that maintain fixed positions regardless of the rotation of the rotor 10, first and second shaping tables 19 and 20, and a ball tightening die 21. Wire bobbins 22 and 23 are provided on the outside of one end of the rotor 10, and a take-up bobbin 2 is provided on the outside of the other end.
4 are provided respectively.

From the wire bobbins 22 and 23, the wire 1a is
, 1a are pulled out, and these wires 1a, 1a are drawn in parallel to form a guide roll 11, a bow 15, a guide roll 12, a first shaping table 19, a ball tightening die 21, a guide roll 13, a bow 16, and a guide. The wires 1b, 1b are wound around the winding bobbin 24 via the roll 14, and are pulled out from the wire bobbins 17, 18.
1b are aligned in parallel to form a second shaping table 20, ball tightening die 21, guide roll 13, bow 16, and guide roll 1.
4 and is wound around the winding bobbin 24. While the rotor 10 is rotating, the winding bobbin 24 rotates and the wires 1a, 1a, 1b, and 1b are sequentially wound around the winding bobbin 24.

[0012] The wires 1a, 1a drawn out from the wire bobbins 22, 23 are twisted once when passing through the guide roll 11, and then twisted once again when passing through the guide roll 12, and are then twisted once to form the first shape. It is shaped when passing through the table 19, and introduced into the ball tightening die 21 in this state.

On the other hand, the wires 1b, 1b pulled out from the wire bobbins 17, 18 are shaped excessively strongly when passing through the second shaping table 21, and in this state, the wires 1b, 1b are drawn out from the ball tightening die 2.
1 and drawn to the wires 1a, 1a.

Wire 1 pulled out from ball tightening die 21
The wires a and 1a are untwisted once when passing through the guide roller 13, and are untwisted once again when passing through the guide roller 14, and in the end these wires 1a and 1a retain the wavy habit due to shaping. It becomes a state with no twist.

Wire 1 pulled out from ball tightening die 21
b, 1b are twisted once when passing through the guide roller 13, and twisted once again when passing through the guide roller 14, so that the wire 1 is twisted around the outer periphery of the wires 1a, 1a.
b and 1b are twisted together and wound onto a winding bobbin 24 as a steel cord S having a 2+2 structure.

The size of the shaping applied to the wires 1a, 1a is as shown in FIG.
The height (depth of the trough) of the undulations between the twist pitches of the wires 1b and 1b twisted around the outer periphery of the wire 1a is 0.3 to 5.0 when the diameter of the wire 1a is d. d, and the shaping rate C for the wires 1b, 1b.
m (%) is 100% or more, preferably 11
The range is approximately 0≦Cm≦140.

In the steel cord S having such a structure, as shown in FIG. 1, due to its shape, the wire 1a
, 1a mutually, wires 1b, 1b mutually, wire bundle A,
The steel cords B contact each other only at partial locations in the longitudinal direction of the cord S, and are spaced apart from each other at most other locations, forming gaps t between them. For example, when the rubber is embedded in the rubber of a tire and the rubber is vulcanized, each wire 1a is
, 1a, 1b, and 1b so that the outer periphery of each of them is filled with rubber. Therefore, each wire 1a, 1a, 1b,
Fretting between 1b is reliably suppressed, and fatigue resistance is significantly improved. Also, each wire 1a, 1a, 1b, 1
Since the outer periphery of b is reliably covered with rubber, its corrosion resistance is also improved.

The mechanical properties of a conventional steel cord S with a 2+2 structure made of wires with a diameter d of 0.25 mm and a steel cord S with a 2+2 structure to which the present invention is applied were measured, and the results are shown in Table 1 below. The results were obtained. In addition, in the products 1 to 8 of the present invention, the size of the shaping of the core wires 1a, 1a is the wire 1 formed by shaping.
The height of the peaks (depth of the valleys) of a is a constant value of 1.2d, and the shaping rate Cm of the wires 1b, 1b on the outer periphery is 1.
Measurements were made with various changes in the range of 05 to 145 (%). Further, fatigue resistance was measured by a three-roll fatigue test method.

[0019]

[Table 1] As is clear from Table 1, it can be seen that the products of the present invention have good fatigue resistance.

Next, a second embodiment of the present invention will be described. The steel cord S in this second embodiment is shown in FIG.
As shown in FIG. 2, it has a 2+3 structure with two core wires 1a, 1a and three outer wires 1b, 1b, 1b. The core wire is shaped in the same manner as in the first embodiment, and the outer wires 1b, 1b
, 1b has over 100% excessive shaping.

[0021] Also in such steel cord S,
Based on the shaping, as in the first embodiment, the wires 1a, 1a are mutually connected, the wires 1b, 1b, 1b are mutually connected,
The wire bundles A and B contact each other only at partial points in the longitudinal direction of the cord S, and are separated from each other at most other points, forming gaps t between them. When the steel cord S is buried in, for example, the rubber of a tire and the rubber is vulcanized, the wires 1a, 1a, 1b, 1b, 1b are arranged so that the outer periphery of each wire 1a, 1a, 1b, 1b, 1b is filled with rubber by the gap t... Therefore, each wire 1
Since fretting between wires a, 1a, 1b, 1b, and 1b is reliably suppressed, fatigue resistance is greatly improved, and the outer periphery of each wire 1a, 1a, 1b, 1b, and 1b is reliably covered with rubber. , its corrosion resistance is also improved.

The mechanical properties of a conventional steel cord S with a 2+3 structure made of wires with a diameter d of 0.25 mm and a steel cord S with a 2+3 structure to which the present invention is applied were measured, as shown in Table 2 below. The results were obtained. In addition, in the products 1 to 5 of the present invention, the size of the shaping of the core wires 1a, 1a is the wire 1 formed by shaping.
The height of the peaks (depth of the valleys) of a is a constant value of 1.2d, and the shaping rate Cm of the wires 1b, 1b, 1b on the outer periphery is
It was measured by changing it variously in the range of 105 to 145 (%). Further, fatigue resistance was measured by a three-roll fatigue test method.

[0023]

[Table 2]

As is clear from Table 2, it can be seen that the products of the present invention have good fatigue resistance. In addition, in the above embodiment, there are two wires on the outer periphery of the two core wires.
This is the case when two wires or three wires are twisted together.
One wire may be twisted around the outer periphery of the core wire, or about 4 to 7 wires may be twisted together.

[0025]

[Effects of the Invention] As explained above, according to the present invention, since the outer periphery of each wire is arranged so as to be filled with rubber, fretting between the wires is reliably suppressed and fatigue resistance is improved. Furthermore, since the outer periphery of each wire is reliably covered with rubber, its corrosion resistance is also improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the cross-sectional state of each part of a steel cord in a first embodiment of the present invention.

FIG. 2 is an explanatory diagram schematically showing the configuration of a twisting device for manufacturing the steel cord.

FIG. 3 is a diagram for explaining the size of shaping applied to the core wire.

FIG. 4 is an explanatory diagram showing the cross-sectional state of each part of a steel cord in a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the cross-sectional state of each part of a conventional steel cord.

[Explanation of symbols]

1a...core wire 1b...Outer wire S...Steel cord

Claims (3)

[Claims] [Claim 1] Two wires each having a shaped core and N wires twisted together with each of the core wires having an excess shaping of more than 100% are formed into a 2+N structure. A steel cord characterized by its structure. 2. The steel cord according to claim 1, wherein N is 2. 3. The steel cord according to claim 1, wherein N is 3.