JP2012045580A - Method for manufacturing steel wire for reinforcement of rubber article, device for manufacturing the same, steel cord for reinforcement of the rubber article, and pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a steel wire for reinforcement of rubber capable of obtaining the steel wire having high strength and excellent in ductility by devising a final wire drawing process in manufacturing the steel wire using a wire rod of a high carbon steel.SOLUTION: In a method for manufacturing the steel wire for reinforcement of a rubber article where final wire drawing is applied to a high carbon steel wire after plating processing, the final wire drawing includes dry wire drawing composed of a plurality of stages at a front stage, and wet wire drawing is carried out after the dry wire drawing. In the wet wire drawing, an area reduction rate of each pass is gradually reduced at a rear stage.

Description

  The present invention relates to a method and apparatus for manufacturing a steel wire for reinforcing rubber articles, a steel cord for reinforcing rubber articles using a steel wire for reinforcing rubber articles obtained by this manufacturing method, and a pneumatic tire.

  Some rubber articles are reinforced with steel wire (hereinafter also referred to as “steel wire” or simply “wire”). For example, in a pneumatic tire, a steel cord formed by bundling a plurality of steel wires and twisting them as necessary is further used to reinforce a carcass ply or a belt.

  The general manufacturing method of the steel wire constituting the steel cord is that the steel wire is subjected to primary wire drawing by a wire drawing machine, followed by primary heat treatment, that is, patenting, followed by secondary wire drawing, and then secondary wire drawing. After heat treatment, that is, patenting treatment again, a plating layer, for example, a brass plating layer is formed on the surface of the steel wire after the secondary wire drawing by plating, and if necessary, for heat diffusion of the plating layer A diffusion heat treatment is performed, followed by final drawing to obtain a steel wire having a predetermined diameter.

  In recent years, technical development has been advanced on reducing the weight of pneumatic tires in order to reduce the global environmental load. Therefore, with regard to carcass and belt, the steel cord is made from a layer-twisted one to a single-twisted one, and further without twisting, thereby reducing the diameter of the steel cord, and thus the thickness of the carcass and belt layer. Thinning has been done. However, even when a single-twisted steel cord or a non-twisted steel cord is used for a carcass or a belt, it is necessary to avoid a decrease in the strength of the pneumatic tire. Therefore, a single-stranded steel cord and a non-twisted steel cord are required to have a predetermined strength.

  The steel wire used for the untwisted steel cord needs to have a larger wire diameter than the wire used for the twisted steel cord. In addition, in order for the untwisted steel cord to have a predetermined strength, it is necessary that the steel wire of the bare wire has a high strength.

  In order to increase the strength of the steel wire, it is conceivable to manufacture the steel wire using a high carbon steel wire having a higher carbon content than that of the conventional steel wire. However, in the manufacture of steel wires using high carbon steel wire rods, it is difficult to increase the amount of processing in the final wire drawing process as in the case of conventional steel wires, and thus it is difficult to design the wire drawing process. Therefore, depending on the manufacturing process, the steel wire obtained by final drawing may not have sufficient mechanical properties such as strength and ductility.

  Patent Document 1 describes that the final wire drawing step is performed by a combination of dry wire drawing for smoothing the plating surface and subsequent wet wire drawing. However, the wire drawing method of the plating-coated metal wire described in Patent Document 1 has only one pass of dry wire drawing, and since the surface reduction rate is low, for smoothing the plating surface of the steel wire. Although sufficient, it was not a method for improving the mechanical properties of steel wires.

JP 2001-1030 A

  The present invention advantageously solves the above-mentioned problem, and when producing a steel wire using a high-carbon steel wire rod, the final wire-drawing process is devised to provide high strength and ductility. Provided are a rubber reinforcing steel wire manufacturing method and manufacturing apparatus capable of obtaining an excellent steel wire, together with a rubber article reinforcing steel cord and a pneumatic tire using the rubber article reinforcing steel wire obtained by this manufacturing method. For the purpose.

  The method for producing a steel wire for reinforcing a rubber article according to the present invention is a method for producing a steel wire for reinforcing a rubber article in which a final drawing is performed on a high carbon steel wire after the plating treatment. The dry drawing is performed, and the wet drawing is performed after the dry drawing.

In the method for manufacturing a steel wire for reinforcing rubber articles according to the present invention, the wet wire drawing is performed by using a diameter of the steel wire after dry drawing as D0 (mm) and a diameter of the steel wire after final wet drawing as D1 (mm). When the following equation (1):
ε = 2 · ln (D0 / D1) (1)
It is preferable to have a wet drawing amount that satisfies ε represented by 2.7 or less, and in the final drawing, the area reduction rate of each pass in the subsequent stage is the area reduction rate of the pass immediately before the pass. And the area reduction rate of the final pass is preferably 6% or less. In the present invention, the latter stage refers to a path in the latter half of the total number of paths including the final path. Furthermore, the steel wire for final drawing contains 1.00% by mass or more of carbon and 0.10 to 0.40% by mass of chromium, and the steel wire after final drawing has a diameter of 0.5 mm. Thus, the breaking strength is preferably 3000 MPa or more. Furthermore, it is more preferable to perform patenting only once on the steel wire after the primary wire drawing before the final wire drawing. Further, after the final wire drawing, a modification treatment for leaving a compressive stress on the surface of the steel wire can be performed.

The steel cord for reinforcing rubber articles according to the present invention is formed by bundling one or more steel wires for reinforcing rubber articles manufactured by the above-described manufacturing method without twisting them.
The pneumatic tire of the present invention uses a steel cord for reinforcing rubber articles made of a steel wire for reinforcing rubber articles manufactured by the above-described manufacturing method for at least one of a ply cord and a belt cord.

  An apparatus for manufacturing a steel wire for reinforcing a rubber article according to the present invention is a manufacturing apparatus for a steel wire for reinforcing a rubber article provided with a wire drawing device that performs final drawing on a steel wire after plating treatment. It consists of a combination of a wire drawing machine and a wet wire drawing machine, and the area reduction rate of each pass in the subsequent stage of this wet wire drawing machine is lower than the area reduction rate of the pass immediately before the pass. . In the present invention, the latter stage refers to a path in the latter half of the total number of paths including the final path.

  In the apparatus for manufacturing a steel wire for reinforcing rubber articles according to the present invention, it is preferable to include a straightening device that causes compressive stress to remain on the surface of the steel wire drawn by the wire drawing device.

  According to the present invention, since the final wire drawing includes a dry wire drawing composed of a plurality of stages in the previous stage, by performing the wire drawing process within a predetermined range by the dry wire drawing of this final wire drawing, It is possible to reduce the surface area reduction ratio, thereby suppressing the amount of heat generated during wet drawing and obtaining a steel wire having excellent ductility.

It is a flowchart of one Embodiment of the manufacturing method of this invention. It is a schematic diagram of the final wire drawing apparatus. It is a graph which shows the area reduction rate of each pass at the time of final wire drawing, and the temperature of a steel wire. It is a graph which shows the area reduction rate of each pass at the time of final wire drawing, and the temperature of a steel wire. It is explanatory drawing of a correction apparatus. It is a graph which shows the area reduction rate of each pass at the time of final wire drawing, and the temperature of a steel wire.

  Hereinafter, embodiments of the method for manufacturing a steel wire for reinforcing rubber articles and an annealing apparatus of the present invention will be described more specifically.

  In FIG. 1, the flowchart of the manufacturing method of the steel wire for rubber article reinforcement of one Embodiment of this invention is shown. FIG. 1 shows a flow chart of an example of a manufacturing process when manufacturing a steel wire used for a carcass or a belt of a pneumatic tire as an example of a steel wire for reinforcing rubber articles.

  In FIG. 1, when final drawing (step S1) is performed on a plated steel wire made of high carbon steel, dry drawing is first performed in multiple stages (ie, multiple passes) (step S11), and then wet drawing is performed. A line is made (step S12). Thereby, a high carbon steel wire is obtained.

  In the present embodiment, in the final wire drawing (step S1), since the dry wire drawing (step S11) by a plurality of passes is performed in the previous stage, it is possible to strongly process the plated steel wire by this dry wire drawing. . Thereby, the area reduction rate in the wet drawing of the final drawing can be reduced. Therefore, it is possible to suppress the amount of heat generated during this wet wire drawing, particularly in the final pass and before, thus preventing embrittlement of the plated steel wire due to this heat generation and improving the ductility of the plated steel wire. be able to.

  Such ductility improvement of the plated steel wire is particularly effective when the plated steel wire is a steel wire having a large diameter, for example, a diameter of 0.5 mm or more, and the steel wire is a high carbon steel. That is, in the conventional final wire drawing, all were drawn by wet wire drawing, so in order to draw a high carbon steel wire containing about 1.0% by mass of carbon, the load in each pass is increased. For this reason, the heat generation of the steel wire at the final wire drawing increased, and the ductility of the steel wire was reduced.

  On the other hand, in the present invention, by performing dry rolling of a plurality of stages at the time of final wire drawing, even in a high carbon steel containing about 1.0% by mass of carbon, each pass at the time of final wire drawing is performed. The load can be reduced, and the heat generation of the steel wire can be suppressed, and as a result, the ductility of the steel wire can be improved. In addition, it is possible to easily manufacture a steel wire having a large diameter with a wire diameter (diameter) of 0.5 mm or more by first performing a plurality of dry rolling operations at the time of final wire drawing. This is particularly advantageously adapted to the steel wire when one or more untwisted steel wires are used as the steel cord used for reinforcing the carcass or belt of the pneumatic tire.

  Therefore, the steel wire having a diameter of 0.5 mm or more and a breaking strength of 3000 MPa or more, more preferably a breaking strength of 3500 MPa or more is manufactured by final drawing on a high carbon steel wire containing 1.00% by mass of carbon. Therefore, the method for manufacturing a steel wire for reinforcing rubber articles according to the present invention is particularly advantageously adapted.

  The manufacturing process before final wire drawing is not particularly limited, and primary wire drawing, heat treatment (patenting), and plating treatment can be performed.

  Although it does not specifically limit about the steel wire used for primary wire drawing, A steel wire, a stainless steel wire, a high carbon steel wire, etc. can be used. Preferably, it is a high carbon steel containing 1.00% by mass or more of carbon and 0.10 to 0.40% by mass of Cr (chromium). By using as a material a steel wire of high carbon steel containing 1.00% by mass or more of carbon and 0.10 to 0.40% by mass of Cr (chromium), the fracture strength is as high as 3000 MPa or more and A thick steel wire having a diameter of 0.5 mm or more can be produced. Moreover, although the diameter of a steel wire is not specifically limited, For example, the thing of about 5.5 mm can be used.

  The primary wire drawing performed on the steel wire can be performed by a dry wire drawing machine under the same wire drawing conditions as in the prior art. The wire diameter of the steel wire after the primary wire drawing can be set to, for example, about 2.6 mmφ.

  The steel cord after the primary wire drawing can be subjected to a heat treatment and a plating treatment after performing a primary heat treatment (patenting) and a secondary wire drawing in the same manner as in the conventional method for producing a steel wire. Further, a single heat treatment and a subsequent plating treatment can be performed without performing the primary heat treatment and the secondary wire drawing. By omitting the primary heat treatment and the secondary wire drawing, in other words, before the final wire drawing, by performing patenting on the steel wire after the primary wire drawing once, More energy saving can be implemented. Therefore, it is preferable to perform patenting only once on the steel wire after the primary wire drawing.

  Moreover, in the manufacturing process of the steel wire, a steel wire having a large diameter, for example, a diameter of 0.5 mm or more can be easily manufactured by omitting the primary heat treatment and the secondary wire drawing after the primary heat treatment. . This is particularly advantageously adapted to the steel wire when one or more untwisted steel wires are used as the steel cord used for reinforcing the carcass or belt of the pneumatic tire. Therefore, when manufacturing a steel wire having a diameter of 0.5 mm or more after the final wire drawing, it is preferable to perform patenting only once.

  When the patenting is performed only once on the steel wire after the primary wire drawing before the final wire drawing, the heat treatment is the same heat treatment device as the heat treatment step before the plating treatment in the conventional general steel cord manufacturing method. Can be performed under the same heat treatment conditions as in the prior art. Thereby, the patenting process of the steel cord after the primary wire drawing, that is, the process of heating the steel wire to austenite and then cooling it to a fine pearlite structure can be performed.

  After the heat treatment, a plating process is performed in order to improve the adhesion to the rubber. This plating treatment is a treatment for coating the surface of a steel wire with a metal or alloy plating such as copper, zinc, or nickel, and brass (brass) plating can be applied as an example. The conditions for the plating process can be the same as those for the conventional steel wire plating process. For example, in the case of brass plating, brass plating which is an alloy of copper and zinc can be formed on the surface of the steel wire by performing diffusion heat treatment after sequentially performing copper plating and zinc plating.

  Next, final wire drawing (step S1) is performed. In accordance with the present invention, the final wire drawing (step S1) includes a plurality of dry wire drawing (step S11) in the previous stage, and after this dry wire drawing (step S11), the wet wire drawing (step S12) is performed. .

  In FIG. 2, the schematic diagram of the final wire drawing apparatus suitable for said final wire drawing is shown. The final wire drawing device 1 shown in FIG. 2 is a combination of a dry wire drawing device 2 and a wet wire drawing device 3. In the dry wire drawing device 2, the unwound steel wire is drawn sequentially through a plurality of dies. After the dry wire drawing, the steel wire is wound up and cut to an appropriate length, and then wet drawing is performed by unwinding the wet wire drawing device 3.

  The dry wire drawing (step S11) preferably includes a plurality of passes, for example, 4 passes or more and 6 passes or less. Therefore, in the dry wire drawing device 2 of FIG. 2, it is preferable to use 4 or more and 6 or less dies in the subsequent stage among a plurality of dies that are sequentially drawn through the unwound steel wire. By performing a plurality of passes of dry wire drawing in the previous stage, the area reduction rate in wet wire drawing can be reduced, and thereby the reduction in ductility of the steel wire can be suppressed. The number of passes for dry drawing can be increased to 4 or more to demonstrate the effect of dry drawing, and wet drawing can be achieved by reducing the diameter of the plated steel wire after dry drawing. The wire can be drawn even with a wet wire drawing machine for fine and medium products other than a wet wire drawing machine dedicated to thick materials. Moreover, by making the dry wire drawing 6 paths or less, it is possible to suppress dropping of the plating formed on the surface of the steel wire. This dry drawing can be applied to several passes of the former drawing before the final drawing.

The amount of processing after the final wire drawing (step S1) after the dry wire drawing (step S11) is as follows. The diameter of the steel wire after the dry wire drawing is D0 (mm), and the diameter of the steel wire after the final wire drawing is D1 (mm). ), The following formula (1):
ε = 2 · ln (D0 / D1) (1)
It is preferable that the processing amount satisfying ε represented by When ε is 2.7 or less, the amount of heat generated in wet wire drawing can be suppressed, and this has the effect that the ductility of the steel wire after the final wire drawing can be further improved.

  In the final wire drawing (step S1), the area reduction rate of each pass in the subsequent stage of the wet wire drawing machine is made lower than the area reduction rate of the pass immediately before the pass, that is, the area reduction rate in the latter half part. Is preferably gradually decreased, and more preferably, the final pass of the wet wire drawing (step S12) and several passes back from the final pass have a lower surface reduction rate than the immediately preceding pass. In the case where a high carbon steel containing 1.00% by mass or more of carbon and 0.10 to 0.40% by mass of Cr (chromium) is used for the steel wire as described above, the latter stage of the final wire drawing step. If the area reduction ratio is large, the steel wire becomes high temperature during wire drawing, and the ductility after the final wire drawing may decrease. According to the inventor's research, such a ductility decrease after the final drawing is performed by changing the last pass and several passes back from the final pass, for example, 12 to 17 passes when the wet drawing is 17 passes, It can suppress more by making a surface-reduction rate lower than a path | pass.

  In FIG. 3 (a), dry drawing is performed 4 passes before wet drawing at the time of final drawing, and then the 12th to 17th passes are reduced from the previous pass in all 17 passes of wet drawing. The area reduction rate of each pass when the surface area is lowered and the high carbon steel is drawn is shown, and the average temperature of the steel wire at that time is shown in a graph in FIG. For reference, in FIG. 4A, dry drawing is not performed at the time of final drawing, and only 14th to 19th passes are reduced from the previous pass in all 17 passes of wet drawing. The area reduction rate of each pass when the high-carbon steel is drawn at a low rate is shown, and the average temperature of the steel wire at that time is shown in a graph in FIG.

  From the comparison between FIG. 3 and FIG. 4, the example of FIG. 3 when dry drawing is performed before wet drawing is more than the example of FIG. 4 when dry drawing is not performed before wet drawing. Also, the peak value of the average temperature of the steel wire at the time of final drawing is low, and the average temperature of the steel wire at the stage after the final drawing is low. As a result, when dry drawing is performed before wet drawing, heat generation of the steel wire during wet drawing is suppressed, and embrittlement of the steel wire is suppressed. It is considered that the decrease can be suppressed.

  As described above, when the area reduction rate of the final pass of the wet wire drawing and the previous pass is lowered, the area reduction rate of the final pass is more preferably 6% or less. By reducing the area reduction rate of the final pass as much as possible to 6% or less, the ductility of the obtained steel wire can be further improved by reducing the temperature of the steel wire at the end of final drawing.

  Note that, according to this embodiment, even if the area reduction rate of the final pass and several passes back from this final pass is lower than that of the immediately preceding pass, a multi-pass dry drawing is performed in the previous stage at the final drawing. By creating a line pass schedule, the total area reduction rate in the final wire drawing can be made the same as the conventional one. Thereby, it becomes possible to carry out the wire drawing of the wet wire drawing using a medium / fine wire drawing machine. Therefore, the great effect that the capital investment which newly installs a thick wire drawing machine becomes unnecessary is acquired.

  Through the final wire drawing according to the present invention, a steel wire having a wire diameter of preferably 0.5 mm or more can be obtained. The steel wire after the final wire drawing preferably has a breaking strength of 3000 MPa or more, and more preferably has a breaking strength of 3500 MPa or more. A steel wire having a diameter of 0.5 mm or more and a breaking strength of 3000 MPa or more is suitably used for an untwisted steel cord.

  After the final wire drawing, the steel wire is wound around a coil and then used for, for example, a carcass ply or a belt of a tire. After this final wire drawing, a straightening process is performed to leave compressive stress on the surface of the steel wire. You can also.

FIG. 5 shows a schematic diagram of an example of the straightening device 10 suitable for use in the straightening process performed after the final wire drawing. In the figure, D is wire drawing machine final drawing, D _L is the final drawing step of the final die, 11 the brass-plated steel wire wound around the brass-plated steel wire W after final drawing W It is a drive capstan that gives the pulling force to the. Reference numeral 12 denotes a straightening roll for applying a compressive stress to the surface of the brass-plated steel wire W. This straightening roll 12 includes a first straightening portion 12A and a second straightening portion 12B, and each straightening portion 12A, 12B has a plurality of rollers 12a arranged in a staggered manner. When the brass-plated steel wire W directly enters the straightening roll 12 without being wound around the drive capstan and passes between these rollers 12a, the brass-plated steel wire W comes into contact with the peripheral surface of each roller. Bending stress is applied alternately. The roller 12a of the first straightening section 12A and the roller 12a of the second straightening section 12B are arranged in a positional relationship that they are rotated by 90 ° around the brass-plated steel wire W. Therefore, the brass-plated steel wire W Tensile stress and bending stress are applied to the surface of the material from four directions, and compressive stress remains.

In correction device 1 shown in FIG. 5, brass-plated steel wire W from final die D _L, without imposing around the driving capstan, it is guided to directly straightening rolls 12. Brass-plated steel wire W is, by being directed directly to the straightening rolls 12, since the pulling force at the final die D _L is added as correction input directly in straightening rolls 12, the straightening rolls 12 Thus, a large compressive residual stress can be easily obtained in the brass-plated steel wire W.

  The brass-plated steel wire W that has passed through the straightening roll 12 is wound around a multi-strand between the grooved multi-pulley 14 and the drive capstan 11 after the moving direction is changed by the guide roller 13. The brass-plated steel wire W that has passed through the multi-row pulley 14 is wound around the bobbin B.

  In the straightening device 10, the rotation of the brass-plated steel wire W, that is, the torsion, is improved by adjusting the way of passing between the multi-row pulley 14 and the drive capstan 11 and adjusting the inclination of the multi-row pulley 14. Further, the straightness, that is, the straightness of the brass-plated steel wire W is improved by adjusting the amount of biting by the straightening roll 12.

  Accordingly, by performing straightening treatment on the brass-plated steel wire W after the final wire drawing by the straightening device 10, the brass-plated steel wire W is directly inserted into the straightening roll and a large compressive stress remains on the surface of the steel wire. By doing so, the ductility of the brass-plated steel wire W can be improved. Further, the straightness of the brass-plated steel wire W is improved by straightening with the straightening roll 12, and the rotational property of the brass-plated steel wire W is further increased by the multi-strand winding of the multi-pulley 14 and the drive capstan 11. As a result, curling and warping of the tire treat can be prevented.

  A steel wire for reinforcing rubber articles manufactured by the method for manufacturing a steel wire for reinforcing rubber articles according to the present invention is used as a rubber reinforcing steel cord by bundling one of them as it is or without twisting them together. Can do. In addition, you may use for the steel cord of a stranded wire similarly to the past. This rubber reinforcing steel cord can be used for at least one of a ply cord belt and a cord of a pneumatic tire.

Example 1
Primary wire drawing was performed on a wire having a diameter of 5.5 mm containing 1.0% by mass of carbon and 0.2% by mass of chromium to obtain a wire diameter of 2.6 mm. Next, after heating to an austenite phase (about 940 ° C.) as a heat treatment, patenting cooling was performed to 500 ° C. under the condition that a clean fine pearlite structure was obtained. Next, copper plating was formed on the surface of the steel wire as the plating treatment, and then zinc plating was formed on the surface of the steel wire plated with copper, followed by diffusion heat treatment to obtain a brass plating having a thickness of 3 to 4 μm.

  Next, final wire drawing was performed. This final wire drawing is performed by dry wire drawing in 4 passes, reducing the wire diameter from 2.60 mm to 1.86 mm, followed by wet drawing in 15 passes, and a steel wire having a diameter of 0.52 mm did. In this dry wire drawing, the value of ε represented by the formula (1) was 2.55. The wire drawing conditions at the time of the final wire drawing and the wire temperature at that time are shown in Table 1, and these are shown in graphs in FIGS. 6 (a) and 6 (b).

As a result of examining the characteristics of the obtained steel wire, the results of the repeated twist test for evaluating the ductility of the steel wire have an RT value of 10 times and a breaking strength of 3540 MPa, which is excellent in ductility and strength. It was.
In the repeated twist test, a repeated twist test apparatus is used to repeatedly give an amount of twist equivalent to three times per 100 times the diameter of the steel wire to the steel wire held so that the axis is a straight line, This is a test for generating cracks in a steel wire. In order to keep the axis of the steel wire under test in a straight line, light tension is applied in the axial direction of the steel wire. The steel wire twisting first predetermined number N ₀ times, returning to the original state by returning twist by the same amount in the opposite direction from that point. This is repeated as one cycle to generate cracks in the steel wire. Here, the predetermined number N ₀ is the number of twists corresponding to 3 times per 100 times the diameter of the steel wire, and the length of the steel wire subjected to the twist is L (mm), the diameter of the steel wire. Is D (mm), this is a value represented by the formula N ₀ = 3 × (L / 100D).
In this repeated twist test, the steel wire sample length L was set to 100 mm, and a weight of 2.0 kg was used as a load. The number of rotations N ₀ corresponding to 3 times per 100 times the wire diameter d of the steel wire is N ₀ = 6.0 times according to the calculation formula of N ₀ = 3 × (L / 100d). Therefore, the steel wire samples were repeatedly given six rotations in the clockwise and counterclockwise directions, and the number of repetitions until a crack was generated was counted. The rotation speed was about 60 rotations / minute.
The RT value indicates that the larger the numerical value, the better the RT value.

(Comparative example)
A steel wire was obtained in the same manner as in Example 1 except that the final wire drawing was performed only in a wet manner with a total of 19 passes. Table 2 shows the wire drawing conditions at the time of the final wire drawing and the wire temperature of the steel wire at that time. These wire drawing conditions are general final wire drawing conditions for all 19 passes by wet wire drawing as shown in FIG.

  When the characteristics of the obtained steel wire were examined, the RT value was 2 times, the breaking strength was 3520 MPa, and the ductility was inferior to that of Example 1.

(Example 2)
In wet wire drawing, the final pass and five passes before the final pass are lower than the area reduction rate of the pass immediately before the pass, and the area reduction rate of the final pass is 63% or less 5.5% A steel wire was obtained in the same manner as in Example 1 except that. Table 3 shows the wire drawing conditions at the time of the final wire drawing and the wire temperature of the steel wire at that time. This wire drawing condition is the wire drawing condition shown in FIG.

  When the properties of the obtained steel wire were examined, the RT value was 20 times, the breaking strength was 3520 MPa), and the ductility was superior to that of Example 1.

(Example 3)
After the final wire drawing, a steel wire was produced in the same manner as in Example 1 except that the straightening device shown in FIG. The steel wire obtained had an RT value of 10 times for the steel wire of Example 1, whereas the steel wire of Example 3 had an RT value of 18 times. Compared with the ductility.

Example 4
After the final wire drawing, a steel wire was produced in the same manner as in Example 2 except that the straightening device shown in FIG. The obtained steel wire had an RT value of 20 times for the steel wire of Example 2, whereas the steel wire of Example 4 had an RT value of 35 times. Compared with the ductility.

  As mentioned above, although the manufacturing method of the steel wire for rubber article reinforcement of this invention was concretely demonstrated using the Example, this invention is not limited by these Examples and does not deviate from the meaning of this invention. It goes without saying that many variations are possible in the range.

DESCRIPTION OF SYMBOLS 1 Final wire drawing device 2 Dry type wire drawing device 3 Wet wire drawing device 10 Straightening device 11 Drive capstan 12 Processing roll 14 Multi-row pulley

Claims (11)

In the method for producing a steel wire for reinforcing rubber articles, in which the final drawing is performed on the high carbon steel wire after the plating treatment,
The final wire drawing includes a dry wire drawing composed of a plurality of stages in the previous stage, and the wet wire drawing is performed after the dry wire drawing. When the diameter of the steel wire after the dry drawing is D0 (mm) and the diameter of the steel wire after the final wet drawing is D1 (mm), the wet drawing is performed by the following formula (1):
ε = 2 · ln (D0 / D1) (1)
The method for producing a steel wire for reinforcing rubber articles according to claim 1, wherein ε represented by the formula (1) has a wet wire drawing amount satisfying 2.7 or less.   The final wire drawing is characterized in that, in the subsequent stage, the area reduction rate of each pass is lower than the area reduction rate of the pass immediately before the pass, and the area reduction rate of the final pass is 6% or less. The manufacturing method of the steel wire for rubber article reinforcement of Claim 1 or 2.   4. The rubber according to claim 1, wherein the steel wire that performs the final wire drawing contains 1.00% by mass or more of carbon and 0.10 to 0.40% by mass of chromium. Manufacturing method of steel wire for article reinforcement.   The steel wire for reinforcing rubber articles according to any one of claims 1 to 4, wherein the steel wire after the final drawing has a diameter of 0.5 mm or more and a breaking strength of 3000 MPa or more. Manufacturing method.   The method for producing a steel wire for reinforcing rubber articles according to any one of claims 1 to 5, wherein patenting is performed only once on the steel wire after the primary wire drawing before the final wire drawing.   The method for manufacturing a steel wire for reinforcing rubber articles according to any one of claims 1 to 6, wherein after the final wire drawing, a straightening treatment is performed to leave compressive stress on the surface of the steel wire.   A steel cord for reinforcing rubber made by bundling one or more steel wires for reinforcing rubber articles manufactured by the manufacturing method according to any one of claims 1 to 7 without twisting them.   A steel cord for reinforcing rubber articles made of a steel wire for reinforcing rubber articles manufactured by the manufacturing method according to any one of claims 1 to 7 is used for at least one of a ply cord and a belt cord. Pneumatic tire. In an apparatus for manufacturing a steel wire for reinforcing rubber articles, comprising a wire drawing device that performs final wire drawing on a steel wire after plating treatment,
This wire drawing device comprises a combination of a dry wire drawing machine and a wet wire drawing machine, and the area reduction rate of each pass in the subsequent stage of this wet wire drawing machine is set to be smaller than the area reduction rate of the pass immediately before the pass. An apparatus for producing a steel wire for reinforcing rubber articles, characterized by being lowered.   11. The apparatus for manufacturing a steel wire for reinforcing rubber articles according to claim 10, further comprising a straightening device that causes compressive stress to remain on the surface of the steel wire drawn by the wire drawing device.

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