JP2014234571A - Steel cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel cord capable of reducing road noise by improving vibration damping and quietness when being used as a tire reinforcement material.SOLUTION: A steel cord contains a filament made of damping alloy. The filament made of damping alloy, as a single body or an aggregate, shows flat or substantially rectangular, non-circular cross-sectional shape and has a layer twisted structure, which comprises an untwisted core using the filament made of damping alloy and a sheath made by twisting multiple filaments together around the core.

Description

  The present invention relates to a steel cord suitable for reinforcing a tire.

  Tires are required to reduce road noise. Therefore, there is a steel cord having a structure in which a damping alloy wire is inserted into a steel filament (Patent Document 1).

JP 2000-8282 A

  A steel cord having a structure in which a damping alloy wire is inserted into a steel filament can improve vibration damping and noise reduction, but the demand for tire vibration damping and noise reduction does not stop. There is a need for improved vibration damping and quietness.

  It is an object of the present invention to provide a steel cord that can be used for a tire to further improve the vibration damping and noise reduction of the tire together with a tire using the steel cord.

  The steel cord of the present invention that solves the above problems includes a filament made of a damping alloy, and the filament made of the damping alloy has a non-circular cross-sectional shape as a single body or an aggregate.

In the steel cord of the present invention, the filament made of the damping alloy can have a flat or substantially rectangular cross-sectional shape, and the plurality of filaments made of the damping alloy are in close contact with each other by surface contact. And the aggregate has a flat shape or a substantially rectangular cross-sectional shape. Further, regarding the cord structure, it is preferable that the cord structure is a layer-twisted cord structure having a core in which a filament made of a damping alloy is used and a sheath in which a plurality of filaments are twisted around the core. In the case of having this layer-twisted cord structure, the core is more preferably non-twisted.
Since the steel cord of the present invention has a non-circular cross section of a single or aggregated filament made of a damping alloy, the occupancy ratio of the filament made of a damping alloy of a single or aggregated body having a noncircular cross section is circular. A configuration higher than the occupation ratio when the same number of filaments in cross section are arranged can be easily achieved.

  Further, in the tire of the present invention, the above-described steel cord is used as a reinforcing material.

  According to the present invention, since the filament made of the damping alloy has a non-circular cross section as a single body or an aggregate, the cross-sectional area of the filament made of the damping alloy in the cord cross section compared to the case of having a circular cross section. The ratio of can be improved. As a result, the vibration damping property of the vibration damping alloy can be improved, and as a result, the silence of the tire can be improved.

It is typical sectional drawing of the example of a filament of non-circular cross-sectional shape. It is typical sectional drawing of the example of a filament of non-circular cross-sectional shape. It is typical sectional drawing of the steel filament of embodiment of this invention. It is typical sectional drawing of the die | dye which has a non-circular die hole.

  Hereinafter, embodiments of the steel cord and the tire of the present invention will be specifically described with reference to the drawings.

  In the steel cord of the present invention, the filament made of the damping alloy has a non-circular cross-sectional shape as a single body or an aggregate. The noncircular cross-sectional shape has a shape other than a perfect circle in the cross section of the filament. This means that the steel filament usually has a perfect circular shape in cross section due to wire drawing using a die, so that such a cross section does not contain a perfect circular filament. To do.

  An example of a non-circular cross-sectional shape is shown in a cross-sectional view in FIG. FIGS. 1A to 1D are examples in which a single filament made of a damping alloy has a non-circular cross-sectional shape. A filament 1 shown in FIG. 1A has a flat shape, more specifically, a cross-sectional shape of a track shape. A filament 2 shown in FIG. 1B has a substantially rectangular cross-sectional shape. The filament 3 shown in FIG.1 (c) has an elliptical cross-sectional shape. The filament 4 shown in FIG. 1 (d) has a triangular cross-sectional shape. A filament 101 shown in FIG. 1E is a comparative example and has a perfect circular cross-sectional shape.

  Among the non-circular cross-sectional shapes shown in FIGS. 1A to 1D, the filament having the track shape of FIG. 1A and the substantially rectangular cross-sectional shape of FIG. This is because an increase in the amount of rubber used can be suppressed when a steel cord including a filament made of a damping alloy is embedded in a rubber member of a tire.

  Another example of a non-circular cross-sectional shape is shown in cross-sectional view in FIG. FIGS. 2A to 2D are examples in which an assembly of a plurality of filaments made of a damping alloy has a noncircular cross-sectional shape. The filament 5 shown in FIG. 2A has a track-shaped cross section as a whole of the filament 5 as a result of the two filaments 5a and 5b having a curved outer surface being in close contact with each other. The filament 6 shown in FIG. 2B has a substantially rectangular cross section as a whole of the filament 6 because the two filaments 6a and 6b having a substantially rectangular cross section are in close contact with each other in surface contact. The filament 7 shown in FIG. 2 (c) has a track-shaped cross section as a whole of the filament 7 because the three filaments 7a, 7b and 7c having a curved or flat outer surface are in close contact with each other. Yes. The filament 8 shown in FIG. 2D has a substantially rectangular cross section as a whole of the filament 8 because the three filaments 8a, 8b and 8c having a substantially rectangular cross section are in close contact with each other. .

  2 (e) and 2 (f) are comparative examples, and the filament 102 in FIG. 2 (e) is an example in which two filaments 102a and 102b having a circular cross section are arranged in parallel. The filament 103 in (f) is an example in which three filaments 103a, 103b and 103c having a circular cross section are arranged in parallel.

  Since the filaments 1 to 4 shown in FIGS. 1A to 1D and the filaments 5 to 8 shown in FIGS. 2A to 2D have non-circular cross-sectional shapes, By using the filament for the steel cord, a steel cord having vibration damping properties in a wide frequency range can be obtained, and a tire using this steel cord becomes a tire having more excellent silence.

  The filaments 1 to 4 shown in FIGS. 1 (a) to 1 (d) and the filaments 5 to 8 shown in FIGS. 2 (a) to 2 (d) are arranged in the same number of filaments having a circular cross section. It is preferable that the occupation ratio is higher than that in the case where the The definition of the occupation ratio will be described with reference to FIG. Note that the occupation ratio can be similarly determined for the filaments 1 to 4 shown in FIG.

  With respect to the filaments 5 to 8, 102, and 103 shown in FIGS. 2A to 2 F, “filament array regions” are defined as regions in which the outline of the filament is virtually surrounded by a square frame. The arrangement region of the filaments in the filament 5 in FIG. 2A is a region 5A in the illustrated broken line. The arrangement region of the filaments in the filament 6 in FIG. 2B is the same as the region in the outline of the filament 6. The filament arrangement region in the filament 7 of FIG. 2C is a region 7A in the illustrated broken line. The arrangement area of the filaments in the filament 8 of FIG. 2D is the same as the area within the outline of the filament 8. The filament arrangement region in the filament 102 of FIG. 2 (e) is a region 102A in the illustrated broken line. The filament arrangement region in the filament 103 of FIG. 2 (f) is a region 103A in the illustrated broken line.

  The “filament occupancy ratio” in each filament shown in FIGS. 2A to 2F is defined as a percentage of the sum of the cross-sectional areas of the filaments relative to the area of the “filament arrangement region” described above. Expressed by the calculation formula, [(sum of filament cross-sectional areas) / (area of filament arrangement region)] × 100.

  The filaments 5 and 6 made of two filaments shown in FIGS. 2A and 2B are more similar to the filament 102 of the comparative example shown in FIG. High filament occupancy. Further, the filaments 7 and 8 made of three filaments shown in FIGS. 2C and 2D are similar to the filament 103 of the comparative example shown in FIG. Also, the filament occupancy is high.

  Regarding the occupation ratio of the filaments defined as described above, the filaments 5 to 8 shown in FIGS. 2A to 2D are filaments of comparative examples in which the same number of filaments having a circular cross section are arranged as described above. It is higher than the occupation ratios of 102 and 103. Due to the high occupation rate of the filament, the amount of the damping alloy used per unit length of the filament is larger than that of the filament of the comparative example. Accordingly, in the steel cord having the damping alloy filament shown in FIG. 1 and FIG. 2, the one having a high filament occupancy ratio is a conventional steel having only one damping alloy filament in a perfect circular cross-sectional shape. As compared with the cord, the damping performance is excellent and the noise reduction can be improved as the amount of the damping alloy used increases.

  Further, since the filaments 5 to 8 shown in FIG. 2 are in surface contact with each other, the shape of the filament can be stably maintained. This is remarkable in the case of FIGS. 2C and 2D in which three or more filaments are arranged in parallel. In addition, the filaments 5 to 8 have a flat outline in the cross section, and contribute to the thinning of the steel cord using these filaments 5 to 8 and eventually the rubber member embedded and reinforced with the steel cord. To do.

  3A to 3E show examples of the steel cord of this embodiment including a filament made of the damping alloy shown in FIGS. 1 and 2. FIG. Moreover, the steel cord of a comparative example is shown to FIG.3 (f)-(h). The steel cord of the present embodiment shown in FIG. 3 is made of the damping alloy shown in FIG. 1 or FIG. 2, and a filament having a non-circular cross-sectional shape is used as a core, and a plurality of steel filaments are used as sheath filaments around the core. Is a layer-twisted steel cord having a so-called n + m cord structure.

  Specifically, the steel cord 10 in FIG. 3 (a) has a track-shaped cross-sectional shape in which the core is composed of one filament 1 shown in FIG. 1 (a), and eight sheath filaments 12 are included. It has a certain 1 + 8 code structure. The steel cord 20 in FIG. 3 (b) has a track-shaped cross-sectional shape in which the core 21 is composed of the two filaments 5a and 5b shown in FIG. 2 (a), and the number of sheath filaments 22 is 2 + 8. The code structure is as follows. The steel cord 30 in FIG. 3C has a substantially rectangular cross-sectional shape in which the core 31 is composed of the two filaments 6a and 6b shown in FIG. 2B, and the number of sheath filaments 32 is 2 + 8. The code structure is as follows. The steel cord 40 in FIG. 3 (d) has a track-shaped cross section in which the core 41 is composed of the three filaments 7a, 7b and 7c shown in FIG. 2 (c), and the sheath cord 42 has ten pieces. It has a certain 3 + 10 code structure. The steel cord 50 in FIG. 3 (e) has a substantially rectangular cross-sectional shape in which the core 51 is composed of the three filaments 8a, 8b, 8c shown in FIG. 2 (d), and the sheath filament 52 has ten pieces. It has a certain 3 + 10 code structure.

  The steel cord 110 of the comparative example of FIG. 3 (f) has a circular cross-sectional shape in which the core is composed of one filament 101 shown in FIG. 1 (e), and the 1 + 6 steel cord 110 has six sheath filaments 112. It has a code structure. In the steel cord 120 of the comparative example of FIG. 3 (g), the core 121 has two filaments 102a and 102b having a circular cross section shown in FIG. 2 (e) arranged in parallel, and eight sheath filaments 122. It has a 2 + 8 code structure. The steel cord 130 of FIG. 3 (h) has a core 131 of 3 + 10 in which three filaments 103a, 103b and 103c having a circular cross section shown in FIG. 2 (f) are arranged in parallel and ten sheath filaments 132 are provided. The code structure is as follows.

  The steel cords 10 to 50 of the present embodiment shown in FIGS. 3A to 3E are made of the above-described vibration damping alloy, and a filament having a non-circular cross-sectional shape is used for a wide range. It has vibration suppression in the frequency range, excellent vibration suppression, can improve the noise reduction, and the steel filament is used for the sheath, so the strength and rigidity of the steel cord is maintained, and the tire When used to reinforce the steel, it is possible to effectively exhibit the damping properties and quietness by the damping alloy without causing deterioration of uniformity and the like.

  Moreover, the steel cords 10-50 of this embodiment shown to Fig.3 (a)-(e) have the cord structure of a layer twist, and have the outline shape whose core is flat shape or substantially rectangular shape. Thus, the contour of the steel cord has a flat shape, and therefore, when used for tire reinforcement, an increase in the amount of rubber used in the rubber member can be suppressed.

  The core is preferably a filament that is not twisted in the longitudinal direction of the filament, in other words, an untwisted filament. When twisting occurs in the longitudinal direction of the filament, the effect of reducing the thickness of the rubber member using the steel cord by flattening the steel cord by using these filaments decreases in the longitudinal direction of the steel cord. This is because a part to be generated occurs.

  The filament made of the damping alloy used for the core is preferably a twin-type damping alloy. A twin-type damping alloy is a damping alloy that utilizes the martensitic twin structure, and is easily deformed by an external input. At this time, energy loss due to hysteresis occurs, thereby damping the vibration. Twin-type damping alloy is not a material that generates dislocations due to plastic deformation when subjected to external input, but only reversibly changes the positional relationship of atoms. Because. Among twin-type damping alloys, a Cu-based alloy is preferable. The reason is that when the steel cord is used to reinforce the rubber member, it undergoes a cross-linking reaction with S (sulfur) present in the rubber existing around the filament, and a strong adhesion to the rubber is obtained.

  The twin type vibration damping alloys include Cu-Al-Mn alloy, Mg-Zr alloy, Mn-Cu alloy, Mn-Cu-Ni-Fe alloy, Cu-Al-Ni alloy, Ti-Ni alloy, Al -Zn alloy, Cu-Zn-Al alloy, Mg alloy, Cu-Si alloy, Fe-Mn-Si alloy, Fe-Ni-Co-Ti alloy, Fe-Ni-C alloy, Fe-Cr-Ni-Mn- Either Si—Co alloy or Ni—Al alloy can be selected.

The filaments 1 to 4 having the noncircular cross-sectional shape shown in FIGS. 1A to 1D can be manufactured by wire drawing using a die having a noncircular die hole or rolling.
Filaments 5 to 8 shown in FIGS. 2A to 2D are prepared by drawing a plurality of steel filaments and drawing these steel filaments through the die holes of a die having a non-circular die hole. Can be manufactured.
Further, the steel cords 10 to 50 shown in FIGS. 3 (a) to 3 (d) have a plurality of sheath filaments around the core by a stranding machine using the filament subjected to the above-described rolling or wire drawing as a core. The steel cord is obtained by performing a stranded wire process for winding the filament.

  An example of a die having a non-circular die hole used for wire drawing is shown in FIG. The die hole of the die d1 in FIG. 4A is flattened as shown in FIG. 4, specifically, the circle is crushed in the diametrical direction so that the two parallel segments and both ends thereof are convex outward. An elliptical shape connected by a curve, in other words, a track shape, and the die hole of the die d2 in FIG. 4B is substantially rectangular.

  The filament 1 of FIG. 1 (a) can be obtained through a single filament in the die d1 of FIG. 4 (a), and the filaments 5 and 7 of FIGS. 2 (a) and (c) can be obtained through a plurality of filaments. . Moreover, the filament 2 of FIG. 1 (b) can be obtained through a single filament through the die d2 of FIG. 4 (b), and the filaments 6 and 8 of FIGS. 2 (b) and (d) can be obtained through a plurality of filaments. Can do.

  By drawing a plurality of filaments with a die having a non-circular die hole, the filaments that form the core of the steel cord can be arranged in a flat shape or the like in a non-twisted state at a time, In this arranged state, the filament can be guided to a twisting machine. Therefore, a flat core can be obtained easily. In addition, since the filaments are plastically deformed by wire drawing and in close contact with the adjacent filaments, the core filaments are not aligned in a stranded wire using a stranded wire machine to be used in a later process. Can be prevented.

  The filament that has been drawn can be once wound on one spool. When twisting with a twisting machine, a plurality of filaments that have been drawn are unwound at a time from one wound spool and supplied to the twisting machine. A plurality of sheath filaments are wound around a filament serving as a core by this twisting machine to obtain a flat steel cord. As this twister, a buncher twister can be used, but a tubular twister is preferable. This is because the tubular stranding machine essentially does not twist the core.

The tire of the present invention uses the steel cord of the present invention as a reinforcing material. The steel cord described above can be used for tire belts, carcass plies, beads, and the like.
The tire using the steel cord of the present invention can be a tire having high vibration damping properties, low road noise and excellent quietness.

  Steel cords having various cord structures shown in Table 1 were produced. The core filament was a twin-type damping alloy with the same composition. In each example, a plurality of core filaments were drawn through a non-circular die hole shown in FIG. 4 (a) to form an assembly in which adjacent filaments were in close contact with each other in surface contact. A steel filament was wound around this aggregate using a tubular twisting machine and twisted together. In the comparative example, the core filament is a filament having a perfect circular cross section, and the filaments are arranged alone or in parallel.

Table 1 shows the area of the arrangement region of the cores of these steel cords, the sum of the cross-sectional areas of the core filaments, the filament occupancy of the cores, the amount of the damping material, and the damping performance. The out-of-plane rigidity ratio and the in-plane rigidity ratio are shown by relative evaluation when the comparative example 1 is set to 100.
From Table 1, each Example was excellent in the damping performance compared with the comparative example. Each example had the strength and rigidity required for the steel cord, and there was no deterioration in uniformity when used in a tire.

1-8 Filament 10, 20, 30, 40, 50 Steel filament 11, 21, 31, 41, 51 Core 12, 22, 32, 42, 52 Sheath filament

Claims (7)

  A steel cord comprising a filament made of a damping alloy, wherein the filament made of the damping alloy has a non-circular cross-sectional shape as a single body or an aggregate.   The steel cord according to claim 1, wherein the filament made of the damping alloy has a flat or substantially rectangular cross-sectional shape.   2. The steel cord according to claim 1, wherein the steel cord has an aggregate in which a plurality of filaments made of the damping alloy are in close contact with each other in surface contact, and the aggregate has a flat shape or a substantially rectangular cross-sectional shape.   The steel cord according to any one of claims 1 to 3, wherein the steel cord has a layer twist structure including a core in which a filament made of the damping alloy is used and a sheath in which a plurality of filaments are twisted around the core. .   The steel cord according to claim 4, wherein the core is untwisted.   6. The occupation ratio of filaments made of a single or aggregate damping alloy having a non-circular cross section is higher than the occupation ratio when the same number of filaments having a circular cross section are arranged. The steel cord according to any one of the above. A tire in which the steel cord according to any one of claims 1 to 6 is used as a reinforcing material.

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