KR20080028555A - Precess for manufacturing a plated steel filament of steel cord for rubber enforcement - Google Patents

Abstract

A manufacturing method of a plated steel wire for a steel cord for reinforcing rubber products is provided to improve initial adhesive force and aging adhesive force by automatically coating and pressing zinc and copper onto a surface of a brass-coated wire during the continuous wire drawing process using an existing wet wire drawing process flow, thereby coating thin films of zinc and copper on the brass-coated wire. A manufacturing method of a plated steel wire for a steel cord for reinforcing rubber products comprises: passing a brass-coated steel wire(2) through a wet drawing bath(4) to draw out the steel wire; passing the steel wire passing through the wet drawing bath through a zinc lubricating bath(7); pressing the steel wire passing through the zinc lubricating bath; passing the pressed steel wire through a copper lubricating bath(9); and pressing the steel wire passing through the copper lubricating bath. The zinc lubricating bath contains 100 to 1,500 ppm of zinc, and the copper lubricating bath contains 200 to 2,000 ppm. The steel wire has an area reduction rate of 5 to 10% in each of the pressing processes.

Description

Manufacturing method of plated steel wire for reinforcing rubber products {precess for manufacturing a plated steel filament of steel cord for rubber enforcement}

1 is a schematic diagram showing a wet drawing operation process used in the method for producing a plated steel wire for steel cord of the present invention.

The present invention relates to a method for manufacturing a steel cord plated steel wire for reinforcing rubber products, and more particularly, to a brass plated wire rod which is stretched in the longitudinal direction while reducing the brass plated wire rod to a wire rod having a desired diameter. In the method, a zinc coated on the surface of the wire rod is installed by installing a crimping die on the wire moving path between the bath and the winder while installing a lubricating bath containing zinc and copper at the outlet of the wet drawing machine. In the process of passing the copper die and copper is bonded to the pole surface of the previously formed plating layer to form a thin zinc and copper plating layer on the surface of the rubber product reinforcement plated steel wire to improve the initial and aging adhesion with the rubber It relates to a manufacturing method.

Steel cords used for reinforcing rubber products, such as tires, are generally processed through steelmaking, hot rolled wire manufacturing, drawing, heat treatment (patenting), drawing, heat treatment, coating (plating), and drawing. It will be described in detail as follows.

First, hot rolled wire of a certain diameter (mostly 5.5 mm) is made of carbon steel having a carbon content of 0.6 to 0.95% by weight, and then subjected to one pattening heat treatment and one to two drawing processes. A steel wire having a diameter of 1.0 to 2.0 mm is produced.

Then, to recover the processed internal metal structure, once again the patten heat treatment is performed, and then copper plating having a thickness of 0.5 to 1.5 μm is performed, and zinc plating of 0.3 to 1.0 μm is sequentially performed thereon. After the thermal diffusion process to obtain a brass plated layer is drawn to a diameter 0.1 to 0.6 mm to produce a steel cord steel wire for reinforcement into rubber products.

Wire rods manufactured in this way are used by twisting into various structures (1x3, 1x4, 2 + 2, 2 + 7, 3 + 6, 3 + 9 + 15, etc.), depending on the application, such as strength, modulus, heat resistance, and heat resistance. Fatigue is superior to other types of inorganic and organic fibers, and is useful for reinforcing rubber products such as tires and conveyor belts.

In general, steel cord steel wire used for tire reinforcement is used by forming a brass plating on the surface of the steel to improve adhesion with tire rubber and final drawing workability of the steel wire manufacturing process. A composition maintained in the range of 60 to 70 wt% and zinc of 30 to 40 wt% is generally used.

The adhesion between brass plated steel wire and tire rubber is known to be influenced by the bond between the copper constituting the brass plating and the sulfur component contained in the rubber.

In other words, the copper cord and the rubber are bonded by chemically reacting copper in the brass plating layer with sulfur in the tire rubber to form a copper sulfide layer.

Copper contained in the brass plating of the steel wire surface is known to act as an accelerator for the adhesion reaction of the rubber during the curing of the rubber during the molding of the tire rubber, in order to obtain a high adhesion between the steel wire and the rubber Since the rate of adhesion reaction must be properly controlled, a copper plating layer containing zinc in an appropriate ratio is formed.

On the other hand, the adhesion between the brass-plated steel wire and the tire rubber decreases with time as compared with the initial vulcanization adhesion due to various factors, and such a decrease in adhesion due to extreme heat and moisture applied to the tire while driving the vehicle. This is because the adhesive layer between the steel wire and the rubber is deteriorated.

Therefore, in order to prolong the life of the tire reinforced by the steel cord, it is also important not only to improve the initial adhesion between the steel cord and the rubber, but also to prevent aging adhesion deterioration caused by extreme heat and moisture over time.

Aging adhesion of steel cords can be improved by lowering the copper composition ratio of the brass plating layer. In this respect, British Patent No. 1,295,419 reduces the absolute amount of copper reacted with sulfur in the rubber by lowering the copper content to 60 wt% or less. However, this method increases β-brass during brass plating due to the low copper content in brass plating. This β-brass is very poor in processability due to its crystal structure, so that the final drawing process after the plating process is performed. There is a drawback of low freshness and a low initial adhesion.

Methods of improving adhesion by adding a third element to brass to form a plating layer made of a ternary alloy are known.

      That is, in French Patent-2,198,830, British Patent-1,122,528, US Patent-2,912,355, and Korean Patent Publication No. 82-631, a method of obtaining a plated layer made of Cu-Zn-Co ternary alloy by adding cobalt after brass plating is performed. EP-188,036 and US Pat. No. 4,222,918, etc., disclose a method of obtaining a plating layer made of ternary alloy by plating nickel after brass plating.

      However, as described above, in order to plate cobalt or nickel as a third element in addition to the copper and zinc plating layers, the plating process is increased by one step. There is a disadvantage of an increase in manufacturing cost.

      In addition, JP-A-90-13046 and JP-A-94-283 disclose organic substances containing a third element instead of a method of plating a third element on a brass plating layer, for example, a hydrocarbon water-based mineral oil. A method is disclosed in which an oil containing cobalt stearate is introduced into a stranded wire of a brass plated steel cord to coat an oil so that a plating layer made of a ternary alloy is formed on the surface of the steel wire.

      However, even in the ternary alloy of Cu-Zn-Co (or Ni) prepared by coating and alloying an organic material including the third element, the brass itself serves as a cathode to the steel wire in a low pH atmosphere. It is pointed out that the formation of a double electrode promotes corrosion, and it is difficult to suppress the phenomenon of corrosion due to the promotion of de-zinc phenomenon of brass in a high pH atmosphere.

      On the other hand, as a way to solve the above disadvantages of the brass itself has been a lot of research on a new plating method that does not use copper at all, and as a specific example, Korean Patent Publication No. 95-32717 After plating, the surface of the cobalt is plated again to form a zinc-cobalt alloy plating layer by a thermal diffusion method to improve corrosion resistance and rubber adhesion of the steel wire cord.

However, in the method of forming the Zn-Co alloy plated layer, the steel wire itself is exposed to a high temperature atmosphere during the thermal diffusion process, and thus, the steel wire is subjected to a heat effect. As a result, the tensile strength of the steel wire decreases, resulting in thermal diffusion equipment and a large amount of energy. It is also pointed out that the manufacturing cost is increased due to the need.

The present invention has been made to solve the above-mentioned problems in the prior art, the installation of a wet bath containing zinc and copper on the outlet side of the wet drawing machine and on the wire transfer path between the bath (bath) and the winder In the process of passing the crimp dies, zinc and copper coated on the surface of the wire rod are bonded to the pole surface of the previously formed plating layer so as to form a thin film of zinc and copper on the surface of the wire rod. An object of the present invention is to provide a method for manufacturing a plated steel wire for reinforcing rubber products having improved aging adhesive strength.

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

Brass-plated wire rod that passes through brass dies installed inside the wet drawing machine so that the wire can be drawn step by step with a certain range of reduction rate and reduced to wire of the desired diameter and stretched in the longitudinal direction In the wire drawing method, a lubrication bath containing zinc and copper is installed on the outlet side of the wet drawing machine, and a crimping die is installed on the wire rod moving path between the lubrication bath and the winder and applied to the wire surface. And the zinc and copper are bonded to the pole surface of the brass plating layer previously formed by the high temperature and the high pressure in the process of passing through the pressing die to form a thin zinc and copper plating layer on the surface. .

In the present invention, the zinc content in the bath (Bath) installed on the outlet side of the wet drawing machine is preferably maintained to about 100 to 1500ppm, if it is contained less than 100ppm of the extreme surface that reacts with the sulfur contained in the tire rubber Due to the lack of zinc, the synergistic effect of the aging adhesive strength of the plated steel wire and the tire rubber is significantly lowered. When it exceeds 1500 ppm, the amount of zinc on the polar surface reacting with the sulfur contained in the tire rubber is excessive and the reaction with the rubber By interfering with the reaction of the initial rubber and copper, the initial adhesive strength drops sharply.

In addition, the copper content in the bath (Bath) installed after the wet drawing machine outlet zinc lubrication bath (Bath) is preferably maintained in the range of about 200 ~ 2000ppm, if less than 200ppm sulfur contained in the tire rubber Insufficient amount of copper on the surface of the surface reacts with the copper, which significantly reduces the initial adhesion between the plated steel wire and the tire rubber. When it exceeds 2000 ppm, the amount of copper on the surface of the surface reacts with sulfur contained in the tire rubber. Over time, as the copper sulfide layer continues to grow over time, the aging adhesion drops sharply.

In the present invention, the reduction rate in the crimping die in which zinc and copper are compressed to the pole surface of the brass plating layer previously formed by high temperature and high pressure is preferably 5 to 10%, and the reduction rate of the crimping die is 5 If it is less than%, there is almost no crimping effect, so the bonding of zinc and copper to the pole surface of the previously formed brass plating layer cannot be expected, and if it exceeds 10%, the drawing workability due to excessive reduction rate is significantly reduced.

1 is a schematic diagram of a wet drawing process used in the method for producing a plated steel wire for reinforcing rubber products of the present invention, the manufacturing process of the plated steel wire for reinforcing rubber products of the present invention will be described as follows.

The brass plated wire rod 2 drawn out from the supply bobbin 1 is guided by the guide roller 3 and moved to the wet bath 4 filled with the wet lubricating liquid therein.

Inside the wet wire (4) (4) is drawn out cones (5, 5 ') consisting of a pair of multi-stage concentric structure, the wire (2) introduced into the wet wire (Bath) (4) these Each stage of the drawing cones 5 and 5 'is sequentially passed through to the outside of the wet bath 4.

At this time, the wire rod 2 passes through a plurality of dice (6a) (6 'a) and a die (6b) mounted on the exit side installed on the path passing through each end of the drawing cone (5) (5'). In the process, stretching occurs with a gradual decrease in diameter from the original diameter.

Meanwhile, a zinc lubrication bath (7) is installed at the wire rod exit side of the wet drawing bath (4), and a crimping die (8a) is mounted at the exit side of the zinc lubrication bath (7). The wire exiting the bath (4) is squeezed out of the zinc component in the crimping die (8a) via a zinc bath (7) and the fresh wire exiting the zinc bath (7) is then After the final drawing is made in the crimping die 8b via the copper lubrication tank (9) installed, the drawing is guided to the take-out capstan 10 to be wound on the take-up bobbin 11.

At this time, in the process of passing through the zinc and copper lubrication bath (Bath) (7) (9) is the zinc and copper components are coated on the pole surface of the plating layer.

As such, the wire rod flowing into the crimping dies 8a and 8b with zinc and copper applied to the pole surface of the brass plated wire rod is subjected to the high pressure and high temperature applied to the surface of the brass plated wire. At the same time as crimping, alloying is performed, and thin zinc and copper plating layers are formed on the surface of the brass plating layer of the fresh wire.

Hereinafter, specific examples and comparative examples of the present invention will be described, but the following examples are merely illustrative and should not be understood as limiting the claims of the present invention.

< Example  1>

Brass-plated diameter 1.45mm steel wire consisting of 65wt% copper and 35wt% zinc is 0.25mm in diameter. In the final step, zinc and copper baths with 800ppm zinc content and 1100ppm copper content were maintained (7). After passing through (8), the reduction ratio of the crimping dies (8a) and (8b) is set to 8% so that the zinc and copper plating layers of the thin film are formed on the pole surface of the brass plating layer, and the plating obtained through the above manufacturing process. The wire rods were twisted together in a stranded wire to fabricate steel cords having a 2 + 2 structure.

< Example  2>

Brass-plated diameter 1.45mm steel wire consisting of 65wt% copper and 35wt% zinc is drawn to 0.25mm in diameter and passed through zinc and copper baths with 1100ppm zinc content and 1500ppm copper content at the final stage. After making the reduction ratio of the crimping dies to 8%, the zinc and copper plating layers of the thin film are formed on the pole surface of the brass plating layer, and the plating wires obtained through the above manufacturing process are twisted with each other in a twisted pair to have a 2 + 2 structure. Table 1 shows the results of the evaluation of the adhesiveness test for the initial adhesion and the aging adhesiveness, the appearance of the adhesiveness, and the fresh workability.

< Comparative example  1>

Brass-plated diameter 1.45 mm steel wire consisting of 65 wt% copper and 35 wt% zinc was passed through a copper bath (8) with a copper content of 4000 ppm at the final stage in freshness to a diameter of 0.25 mm. A thin film copper plated layer is formed on the pole surface of the brass plated layer with the reduction ratio of the die 8b at 8%, and the steel wire having a 2 + 2 structure is twisted by twisting the plated wires obtained through the above manufacturing process in a twisted pair. Table 1 shows the results of the adhesion test for the initial adhesion and the aging adhesion, the evaluation of the adhesive appearance, and the evaluation of the fresh workability.

< Comparative example  2>

Brass-plated diameter 1.45mm steel wire consisting of 65wt% copper and 35wt% zinc was drawn to 0.25mm diameter in the final stage to pass through zinc bath (7) with zinc content maintained at 3000ppm and then crimped A thin film galvanized layer is formed on the pole surface of the brass plated layer with the reduction ratio of the die 8a at 8%, and the steel wire having a 2 + 2 structure is twisted by twisting the plated wires obtained through the above manufacturing process in a twisted pair. Table 1 shows the results of the adhesion test for the initial adhesion and the aging adhesion, the evaluation of the adhesive appearance, and the evaluation of the fresh workability.

< Comparative example  3>

Brass-plated diameter 1.45 mm steel wire consisting of 65 wt% copper and 35 wt% zinc to a diameter of 0.25 mm. In the final step, zinc and copper baths with a zinc content of 30 ppm and a copper content of 1100 ppm were maintained (7). After passing through (8), the reduction ratio of the crimping dies (8a) and (8b) is set to 8% so that the zinc and copper plating layers of the thin film are formed on the pole surface of the brass plating layer, and the plating obtained through the above manufacturing process. The wire rods were twisted together in a stranded wire to fabricate steel cords having a 2 + 2 structure.

< Comparative example  4>

Brass-plated diameter 1.45mm steel wire consisting of 65wt% copper and 35wt% zinc to be 0.25mm in diameter. Zinc and copper baths with 800ppm zinc content and 50ppm copper content at final stage (7) After passing through (8), the reduction ratio of the crimping dies (8a) and (8b) is set to 8% so that the zinc and copper plating layers of the thin film are formed on the pole surface of the brass plating layer, and the plating obtained through the above manufacturing process. The wire rods were twisted together in a stranded wire to fabricate steel cords having a 2 + 2 structure.

< Comparative example  5>

Brass-plated diameter 1.45mm steel wire consisting of 65wt% copper and 35wt% zinc to be 0.25mm in diameter. In the final step, zinc and copper baths with zinc content of 1100ppm and copper content of 1500ppm are maintained (7) After passing through the (8), the reduction ratio of the crimping dies (8a) (8b) to 3% to produce a thin film of zinc, copper plating layer on the pole surface of the brass plating layer, the plating obtained through the above manufacturing process The wire rods were twisted together in a stranded wire to fabricate steel cords having a 2 + 2 structure.

 < Comparative example  6>

Brass-plated diameter 1.45mm steel wire consisting of 65wt% copper and 35wt% zinc to be 0.25mm in diameter. In the final step, zinc and copper baths with zinc content of 1100ppm and copper content of 1500ppm are maintained (7) After passing through (8), the reduction rate of the crimping dies (8a) and (8b) is set to 15% so that the zinc and copper plating layers of the thin film are formed on the pole surface of the brass plating layer, and the plating obtained through the above manufacturing process. The wire rods were twisted together in a stranded wire to fabricate steel cords having a 2 + 2 structure.

< Comparative example  7>

In the conventional method, a steel plate having a 2 + 2 structure is fabricated by twisting plating wires obtained by drawing a brass-plated diameter 1.45 mm steel wire made of 65 wt% copper and 35 wt% zinc to 0.25 mm in diameter in a twisted pair. And the results of the evaluation of the adhesion test and the adhesion appearance and the fresh workability for aging adhesion is shown in Table 1.

Physical property measurement method used in the present invention is as follows.

 1) Initial Adhesion (Kg / 0.5 “) and Initial Adhesion Appearance (%)

     It was measured according to ASTM D-2229.

 2) Aging Adhesion (Kg / 0.5 “) and Aging Adhesion Appearance (%)

    * Salt aging test: Test after 12 days immersion in 20% sodium chloride solution

    * Moisture-resistant aging test: Test after storage for 12 days in 70 ℃ × 96% constant temperature and humidity chamber

    * Heat aging test: Test after storage for 12 days in a drying furnace at 100 ℃

 3) Fresh workability

   * Disconnection rate (times / ton)

     : The number of times wire was cut during production of 1 ton of wire in the final drawing process was evaluated.

In Table 1 above,

A: index for adhesion at initial adhesion test

B: Index for adhesion at salt aging test

C: Index for adhesion at the time of wet heat aging test

D: Index for adhesive force during heat aging test

E: Index for the adhesive appearance during the initial adhesion test

F: Index for adhesive appearance in salt aging test

G: Index for the adhesive appearance during the heat-resistant aging test

H: As the index for the adhesive appearance in the heat-resistant aging test, all the indexes were converted in terms of 100 when the result of the conditions of 1100 ppm of zinc, 1500 ppm of copper, and 8% of crimp die reduction ratio was 100.

As shown in the above examples and comparative examples, the steel wire for reinforcing steel products was manufactured in the embodiment of the present invention to prevent the improvement of the initial adhesive strength and the aging adhesive strength with the rubber.

As described above, the plated wire for manufacturing steel cord manufactured by the method of the present invention may be continuously wired by utilizing the existing wet drawing workflow without requiring a separate plating process or thermal diffusion process on the surface of the brass plated wire. Since thin film zinc and copper plating are performed by automatic zinc and copper coating and pressing of the copper component, there is an advantage of improving the initial adhesive strength and aging adhesive strength without deteriorating the fresh workability.

Claims (3)

In drawing the steel wire plated with brass through a wet drawing bath, the steel wire passing through the wet drawing bath is passed through a zinc lubrication bath, followed by crimping, followed by a copper lubrication bath. Method for producing a plated steel wire for reinforcing steel products characterized in that the crimping after passing through. The steel for reinforcing rubber products according to claim 1, wherein zinc is contained in the zinc lubrication bath in the range of 100 to 1,500 ppm, and copper is contained in the copper lubrication bath in the range of 200 to 2,000 ppm. Manufacturing method of plated steel wire for cord. The method of manufacturing a plated steel wire for reinforcing rubber products according to claim 1, wherein each reduction rate during crimping is 5 to 10%.

Images