JP5625604B2 - Steel cord for rubber reinforcement - Google Patents

Description

  The present invention relates to a steel cord for reinforcing rubber, and more particularly, to a steel cord for reinforcing rubber that is improved in rubber permeability without reducing cord strength.

  In general, a steel cord that reinforces a rubber product represented by a conveyor belt or the like is provided with a measure for preventing corrosion due to moisture in the rubber. In order to protect the steel cord from corrosion, the steel wire is plated with zinc, etc., and the cord structure is made into a form in which rubber easily penetrates between the strands. Many proposals have been made (see, for example, Patent Document 1).

  In particular, reinforcing cords for conveyor belts used under high tension have been required to have strong cord strength and at the same time to be protected from moisture corrosion. In order to meet these demands, conventionally, as shown in FIGS. 5A to 5C, a core strand 2 in which a plurality of steel monofilaments are twisted and a plurality of side strands 3 twisted around the core strand 2 are provided. 1 + 6 + 12 + 6 × (1 + 6 + 12) structure shown in FIG. 5A (hereinafter referred to as 7 × 19 configuration code in the present invention) and 1 + 6 + 6 × (1 + 6) structure shown in FIG. 5B (hereinafter referred to as 7 in the present invention). Steel cord 1 ′ having a structure of 1 × 3 + 6 + (6 + 6) + 6 × (1 + 6 + (6 + 6)) (hereinafter referred to as 7 × SeW (19) configuration code in the present invention) shown in FIG. Has been used.

  And in order to ensure the permeability of the rubber in these steel cords 1 ', the cores of the steel cords 1' are slightly crushed and the cores are changed while changing the combinations of the strand diameters in the respective layers. A plurality of side strands 3 have been twisted around the strand 2 in layers. However, although it was possible to secure the rubber permeability to some extent by the combination of the wire diameters, the rubber permeability has a limit, and further improvement has been demanded.

  On the other hand, in order to ensure the permeability of rubber, the core strand is subjected to a substantially spiral kneading process, and the side strand having a slightly smaller outer diameter than the core strand is twisted around the outer periphery. (See Patent Document 2). However, in this proposal, since the core strand and the side strand are each made of monofilament, the strength of the cord as a steel cord is insufficient. There was a limit to ensuring permeability.

JP-A-6-240590 Japanese Utility Model Publication No. 6-42993

An object of the present invention is to solve the above-mentioned problems, and a first object is to provide a steel cord for rubber reinforcement that can improve rubber permeability without reducing cord strength. near is, the second object is to reduce the production cost of the steel cord.

The steel cord for reinforcing rubber according to the present invention that achieves the above object is obtained by twisting a plurality of side strands in which a plurality of strands are twisted around a core strand in which a plurality of strands are twisted together. In the steel cord for reinforcing rubber having a multi-strand structure, the outer diameter of the core strand and the outer diameter of the side strand are made equal to each other, and prior to twisting of the side strand, The spiral stranding process is performed in the longitudinal direction of the core strand, and the spiral outer diameter of the core strand after the crimping process is 1.05 to 1.30 times the outer diameter of the core strand. It is characterized by that.

Furthermore, in the above-described configuration, it is preferable to configure as described in (1) to (4) below.
(1) you pre SL imprint helical pitch of the core strands after processing to 0.20 to 0.60 times the pitch twisting of the side strands adjacent to the core strand.
(2) you to the steel cord structure 7 × 19 configuration code or 7 × 7 configuration code. In this case, the twisted structure of the core strand and the side strand may be equal to each other.
(3) The steel cord has a 7 × SeW (19) configuration code.
(4) Used for reinforcing the conveyor belt.

According to the present invention described above, in the steel cord for rubber reinforcement having a multi-strand structure in which a plurality of side strands are twisted around the core strand, prior to the twisting of the side strands, Since the spiral kneading process is applied in the direction, the rubber that has permeated through the side strands is efficiently penetrated toward the center of the core strand, preventing corrosion of the steel cord due to moisture over a long period of time. No reduction in steel cord strength.
Moreover, in the present invention, the spiral outer diameter of the core strand after the soldering process is 1.05-1.30 times the outer diameter of the core strand before the soldering process. The strength of the steel cord cord can be appropriately secured while maintaining good properties.
Furthermore, in the present invention, since the outer diameter of the core strand and the outer diameter of the side strand are equal to each other, it is possible to configure the outer diameter of each strand constituting the steel cord by a small number of types. Production costs can be reduced.

It is sectional drawing of the steel cord for rubber reinforcement by embodiment of this invention. It is explanatory drawing which takes out and shows the core strand in the steel cord of FIG. 1, (a) is the sectional drawing, (b) is the partial side view. It is sectional drawing of the steel cord for rubber reinforcement by other embodiment of this invention. It is sectional drawing of the steel cord for rubber reinforcement by other embodiment of this invention. FIG. 3 is a cross-sectional view of a conventional steel cord for reinforcing rubber, where (a) is a cross-sectional view corresponding to the steel cord of FIG. 1, (b) is a cross-sectional view corresponding to the steel cord of FIG. 3, and (c) is the steel of FIG. It is sectional drawing equivalent to a code | cord | chord.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view of a rubber-reinforcing steel cord according to an embodiment of the present invention. A rubber-reinforcing steel cord 1 according to the present invention has a single core in which a plurality of wires (19 in the figure) are twisted together. It has a multi-strand structure in which a plurality of (six in the figure) side strands 3 in which a plurality of (19 in the figure) strands are twisted around the strand 2 are twisted together.

In the present invention, the outer diameter of the core strand 2 and the outer diameter of the side strand 3 are made equal to each other , and the core strand 2 is directed in the longitudinal direction of the core strand 2 prior to twisting of the side strand 3. Then , as described below, a spiral kneading process is performed. The dotted line R in the figure shows the outer shape of the core strand 2 after the squeezing process.

  As described above, the core strand 2 is preliminarily spiraled in the longitudinal direction of the core strand 2, so that the rubber that has permeated the side strand 3 efficiently penetrates toward the center of the core strand 2. Therefore, corrosion of the steel cord 1 due to moisture is prevented for a long period of time, and the strength of the cord of the steel cord 1 is not reduced.

  In the embodiment of FIG. 1, the case where the structure of the steel cord 1 is a 7 × 19 configuration cord having a 1 + 6 + 12 + 6 × (1 + 6 + 12) structure is illustrated, but the structure of the steel cord 1 of the present invention is limited to this. is not.

And in this invention , the helical outer diameter D (refer FIG. 2 (a) and (b) ) of the core strand 2 after a crimping process is 1.05-1.30 times the outer diameter Do of the core strand 2, Preferably, it is adjusted to be 1.10 to 1.25 times . Thereby, the cord strength of the steel cord 1 can be ensured appropriately. Here, if the spiral outer diameter D is less than 1.05 times the outer diameter Do of the core strand 2, the rubber permeability to the core strand 2 will be insufficient, and if it exceeds 1.30 times, the cord strength of the steel cord 1 will be low. It will be insufficient.

  More preferably, the helical pitch P of the core strand 2 after the crimping process is 0.20 to 0.60 times the twisting pitch (not shown) of the side strand 3 adjacent to the core strand 2, preferably 0.30. It may be adjusted to be 0.50 times. Thereby, while the twisting operation | work of the side strand 3 can be performed smoothly, the form of the steel cord 1 can be stabilized and the fall of cord strength can be suppressed.

In the conventional rubber reinforcing steel cord corresponding to the embodiment of FIG. 1, the outer diameter of the core strand 2 is set to ensure the strength of the cord of the steel cord 1 ′ as illustrated in FIG. 5 (a). The side strand 3 is twisted around the core strand 2 by making it larger than the outer diameter of the side strand 3. Therefore, when the core strand 2 and the side strand 3 are formed in the same twisted structure as shown in FIG. 5A, each strand constituting the steel cord 1 ′ has four or more types of outer diameters. It was necessary to use a steel filament.

On the other hand, in the steel cord 1 for rubber reinforcement of the present invention shown in FIG. 1, the outer diameters of the core strand 2 and the side strand 3 are equal to each other as described above. Thus, when the outer diameter of the core strand 2 and the side strand 3 is made equivalent, the outer diameter of each strand which comprises the steel cord 1 can be comprised by three types. Thereby, the production cost of the steel cord 1 can be reduced. Furthermore, the twist structure of the core strand 2 and the side strand 3 can be made equivalent as in the embodiment of FIG. In this case, the productivity of the steel cord 1 can be improved.

  FIG. 3 is a cross-sectional view of a rubber reinforcing steel cord 1 according to another embodiment of the present invention. In this embodiment, the structure of the steel cord 1 is formed as a 7 × 7 constituent cord having a 1 + 6 + 6 × (1 + 6) structure. ing.

Also in the case of this embodiment, the outer diameters of the core strand 2 and the side strand 3 are made equal to each other as in the case of the embodiment of FIG. Thus, when the outer diameter of the core strand 2 and the side strand 3 is made equivalent, the outer diameter of each strand which comprises the steel cord 1 can be comprised by two types. Thereby, the production cost of the steel cord 1 can be significantly reduced.

  Furthermore, the productivity of the steel cord 1 can be improved by equalizing the twisted structure of the core strand 2 and the side strand 3 as in the embodiment of FIG. In addition, about the effect by this embodiment, since it is the same as that of the case by embodiment of FIG. 1, the overlapping description is abbreviate | omitted.

FIG. 4 is a cross-sectional view of a rubber reinforcing steel cord 1 according to still another embodiment of the present invention. In this embodiment, the structure of the steel cord 1 is a 1 × 3 + 6 + (6 + 6) + 6 × (1 + 6 + (6 + 6)) structure. The 7 × SeW (19) configuration code is formed. Also in this embodiment, the outer diameter of the core strand 2 and the outer diameter of the side strand 3 are made equal to each other . In addition, since the effect by this embodiment is also the same as that of the case by embodiment of FIG. 1, the overlapping description is abbreviate | omitted.

  In the embodiment of FIGS. 1 and 3 described above, the twisted structure of the core strand 2 and the side strand 3 is shown to be equal to each other. However, in the steel cord 1 for rubber reinforcement of the present invention, the cord strength and the rubber From the viewpoint of ensuring a high balance with permeability, the twisted structures of the core strand 2 and the side strand 3 can be made different.

As described above, the steel cord 1 for rubber reinforcement according to the present invention has a core strand 2 and an outer diameter of the side strand 3 that are equal to each other, and before the side strand 3 is twisted, the core strand 2 is subjected to a helical squeezing process at a predetermined ratio in the longitudinal direction of the core strand 2, and by improving the permeability of the rubber to the steel cord 1, while preventing corrosion due to moisture in the rubber, It is designed to improve flexibility without reducing cord strength, and can be preferably applied as a reinforcing cord for conveyor belts used particularly under high tension.

  The steel cords are referred to as “7 × 19 component cords”, “7 × 7 component cords” and “7 × SeW (19) component cords”, respectively. The structure of these steel cords, the outer diameter of the cords, and the outer side of the core strand before and after the brazing The conventional cords shown in FIGS. 5A to 5C (corresponding to the conventional examples 1 to 3) in which the diameter and the outer diameter of the side strands are made different as shown in Table 1 and the core strand is not subjected to the staking process. ) And the cords of the present invention (corresponding to Examples 1 to 6) and comparative cords (Comparative Examples 1 and 2) shown in FIGS.

  Each of these cords is embedded in rubber, vulcanized in a mold under the same conditions, and the upper, lower, left and right sides of the cord are covered with 2 mm thick rubber, and a conventional test piece having a square cross section and a length of 460 mm. (Conventional Examples 1 to 3), test specimens of the present invention (Examples 1 to 6) and comparative test specimens (Comparative Examples 1 and 2).

  In addition, in this invention test piece (Examples 1-6) and comparative test piece (Comparative Examples 1 and 2), the spiral outer diameters of the core strands after the kneading process are respectively twisted by the side strands adjacent to the core strands. The pitch was set to 0.45 times the pitch.

  About these 11 types of test pieces, rubber permeability and cord strength were measured by the following methods, and the results are shown in Table 1.

[Rubber permeability]
In accordance with the “air permeability test method” according to the Australian standard (AS-1333), 100 kPa of air pressure is injected into each test piece from one end in the longitudinal direction of the test piece. The air pressure permeate | transmitted to the edge part side was measured, and the result was described in Table 1. The smaller the air pressure, the better the air permeability resistance and the better the rubber permeability to the steel cord.

  Furthermore, after that, the steel cord was disassembled, the core strand was taken out, the amount of rubber (%) attached to the periphery of the core strand was measured by visual observation, and the results are also shown in Table 1.

[Strong code]
The load at the time of breaking when each test piece was pulled in the longitudinal direction was measured, and the result was used to evaluate the cord strength. The measurement results are obtained by using an index in which the conventional example 1 is 100 for the examples 1 and 2, the index in which the conventional example 2 is 100 for the examples 3 and 4, and the conventional example 3 for the examples 5 and 6. The results are shown in Table 1 according to an index of 100. The larger the value, the better the code strength.

  According to Table 1, in the “7 × 19 configuration code” and the “7 × 7 configuration code”, the cord of the present invention improves the strength of the cord and the permeability of the rubber as compared with the conventional cord. I understand that. In Comparative Example 1, the core strand outer diameter ratio (D / Do) before and after the soldering was too small, so that the rubber permeability decreased. In Comparative Example 2, the core strand outer diameter ratio (D and before the soldering) (D Since / Do) was too large, it was confirmed that the code strength was reduced.

  In addition, in the “7 × SeW (19) configuration code”, the rubber permeability of the conventional cord was not improved at all, whereas the cord of the present invention improved the cord strength and improved the rubber permeability. It was confirmed that

1 Steel cord for rubber reinforcement 2 Core strand Do Outer diameter of core strand D Spiral diameter of core strand P Spiral pitch of core strand 3 Side strand

Claims (6)

In a steel cord for rubber reinforcement composed of a multi-strand structure in which a plurality of side strands in which a plurality of strands are twisted are twisted around one core strand in which a plurality of strands are twisted together,
The outer diameter of the core strand and the outer diameter of the side strand are made equal to each other, and prior to twisting of the side strand, the core strand is spirally wound in the longitudinal direction of the core strand. A steel cord for rubber reinforcement in which a spiral outer diameter of the core strand after being subjected to the crimping process is 1.05 to 1.30 times larger than an outer diameter of the core strand while being processed . 2. The steel cord for rubber reinforcement according to claim 1, wherein the helical pitch of the core strand after the kneading process is 0.20 to 0.60 times the twisting pitch of the side strand adjacent to the core strand. The steel cord for rubber reinforcement according to claim 1 or 2, wherein the structure of the steel cord is a 7x19 constituent cord or a 7x7 constituent cord. The steel cord for rubber reinforcement according to claim 3, wherein twist structures of the core strand and the side strand are equal to each other. The steel cord for rubber reinforcement according to claim 1 or 2, wherein the steel cord has a structure of 7 x SeW (19). The steel cord for rubber reinforcement according to any one of claims 1 to 5, which is used for reinforcing a conveyor belt.

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