JPH04237531A - Manufacture of copper clad steel wire - Google Patents

Abstract

PURPOSE:To suppress slippage on the boundary part during drawing and to improve adhesive strength by specifying a ruggedness of the surface of a core steel wire. CONSTITUTION:The 3.0-5.5mmphi steel wire on the surface of which 1-10mum ruggedness are given to the >=40% surface area is used as a core material. A copper tape being 0.1-2.0mm in thickness and parallel with the lengthwise direction of the core stock is formed into a pipe having an inner diameter larger than the wire diameter of the steel wire by 3-5mm and after the butted part is welded, the clearance between the core stock and the pipe is eliminated by diameter contracting work. Taking the wire diameter of the clad steel wire without clearance for a reference, cold drawing of a reduction of area, 5-15% per pass is repeated and the drawing is executed so that the total reduction of area exceeds 50%. Consequently, the boundary part between copper and steel indicates a favorable adhesion and is strong in fatigue strength.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copper-clad steel wire having a thick cladding layer and high fatigue properties. The copper clad steel wire obtained by the present invention has Z
By applying N plating, Ni plating, etc., a highly corrosion-resistant wire can be easily manufactured, and by increasing the conductivity, it can also be used as a conductive wire. The copper-clad steel wire obtained according to the present invention can be applied to wires for various uses that utilize the conductivity of copper and the strength characteristics of steel.

0002

[Prior Art] Currently, methods for cladding steel wire with copper include electroplating, which thickens copper by electroplating;
Pipe cladding method in which steel wire is welded and coated with copper tape and then cold drawn; pipe insertion method in which steel wire is inserted into a copper pipe and cold drawn; copper is cast around a steel billet and hot rolled The billet hot rolling method, in which steel wires are made into wire rods, and the molten metal immersion method, in which molten copper is attached to steel wires and solidified, are being considered. Among these, the electroplating method, the pipe-making cladding method, and the molten metal immersion method are often used industrially.

[0003] Each of these cladding techniques has its own characteristics. For example, in the case of electroplating, a thin and uniform cladding layer can be obtained with good adhesion, but thick plating takes time and the processed wire diameter is relatively small, resulting in very low productivity. However, it is difficult to treat waste liquid, which is a pollution problem, and the cost is high. When using the molten metal dipping method and the billet hot rolling method, a thicker coating is possible than when using the plating method, but the thickness of the cladding layer is non-uniform and problems such as the formation of an alloy layer are likely to occur. In the case of the pipe manufacturing cladding method and the pipe insertion method, the thickness of the cladding layer can be made thicker and manufacturing is possible at low cost. Problems such as slippage and bulge deformation at boundaries are likely to occur.

[0004] In the pipe-making cladding method according to the present invention, various means have been proposed for improving adhesion. For example, Japanese Unexamined Patent Publication No. 154777/1984 proposes a method in which the surface of the core material is plated with the same type of metal as the cladding metal. However, this method requires large equipment for plating, and the advantages of the pipe cladding method, such as the simplicity of the manufacturing method and low cost, are not fully obtained. Also, JP-A-1
-245913 proposes roughening the surface of the core material by brushing, but the scratches caused by brushing tend to cause small voids to form at the boundary between the cladding layer and the core material after adhesion. Since these voids deteriorate the fatigue properties of the finished wire, it is necessary to add a process such as heat treatment when using it as a rope, electric wire, or conducting wire. Furthermore, brushing
0.1 mm because the surface is deeply scraped by scratching.
It is not possible to clad a thin copper tape with a thickness of

[0005]

[Problems to be Solved by the Invention] As mentioned above, according to the pipe manufacturing cladding method, the thickness of the cladding layer can be increased, and it can be manufactured at low cost because it can be obtained only by cold working. However, due to the weak adhesion of the cladding layer, slipping may occur at the boundary between the steel wire and the cladding layer during wire drawing.
Problems such as bulge deformation tend to occur, and if you brush and scratch to improve adhesion, small voids will occur at the boundary between the cladding layer and the core material after adhesion, and this will cause problems in the finished product. Problems such as deterioration of the fatigue characteristics of wires occurred.

The present inventors conducted many experiments to solve the above problems, and found that slippage at the boundary during wire drawing can be suppressed as the surface unevenness increases; It has been found that when the surface irregularities become too large, the adhesion decreases and the fatigue properties deteriorate. In the present invention, there is an optimum value for the size of the surface unevenness of the steel wire, and by clarifying the processing conditions in this case, it is possible to suppress slippage at the boundary between copper and steel during wire drawing, and at the same time The aim is to improve the fatigue characteristics of copper-clad steel wire at the finished wire diameter by improving the adhesion of the parts.

[0007]

[Means for Solving the Problems] The present invention was devised in order to solve the above technical problem, and it uses a steel wire as the core material, and a copper tape is formed around it into a pipe shape. When manufacturing a copper clad steel wire, which consists of TIG welding the butt part and then reducing the diameter of the pipe and core material and joining them, the surface is made with irregularities of 1 μm or more and 10 μm or less, making up 40% of the surface area.
Wire diameter of 3.0mm or more and 5.5m attached to 0% or more part
m or less steel wire as a core material, and a copper tape with a thickness of 0.1 mm or more and 2.0 mm or less, which is vertically aligned in the longitudinal direction of this core material, is 3.0 mm or more and 5.0 mm or more than the wire diameter of the steel wire. The following is formed into a pipe shape with a large inner diameter, and after welding the butt parts, the gap between the core material and the pipe is eliminated, and the area reduction rate in one pass is based on the wire diameter of the clad steel wire with no gap. Repeated cold drawing of 5% or more and 15% or less until the total area reduction rate is 5.
This is a method for producing a copper clad steel wire, which is characterized by drawing the copper clad steel wire so that the copper clad steel wire is 0% or more.

That is, the present invention improves the adhesion and fatigue strength of the cladding layer by suppressing the surface irregularities of the core steel wire, and eliminates the gap between the core material and the pipe before drawing the cladding layer. By completely suppressing slippage at the boundary,
This makes it possible to improve the properties and manufacturing costs of copper-clad steel wire. In the present invention, 1 on the surface of the steel wire
To create an unevenness of 1μm or more and 10μm or less, the unevenness is 1μm.
This is because if it is less than 10 μm, the frictional resistance between the copper pipe and the core steel wire will be significantly reduced, causing the cladding layer boundary to slip during the wire drawing process, leading to wire breakage.
This is because if the voids become larger, small voids remain at the boundary between the cladding layer and the core material of the copper-clad steel wire after wire drawing, which may deteriorate the fatigue characteristics of the wire. If voids are formed, they can be eliminated by applying a heat treatment step after wire drawing, but this increases the manufacturing cost significantly.

[0009] Furthermore, the area on which the unevenness of 1 μm or more and 10 μm or less is provided should be at least 40% of the entire surface area of the core steel wire. This is because if it is less than 40%, the frictional resistance between the copper pipe and the core steel wire will be extremely small, and the cladding layer boundary will slip during the wire drawing process, leading to wire breakage. The reason why a steel wire with a wire diameter of 3.0 mm or more and 5.5 mm or less is used as the core material is because if the wire diameter is less than 3.0 mm, the difference between the steel wire of the core material and the minimum inner diameter of the copper pipe will be too large. This is because it becomes difficult to eliminate the gap between the core material and the pipe.
This is because if it is larger than 5.5 mm, the rigidity of the steel wire will increase and welding will become difficult.

[0010] The thickness of the copper tape is 0.1 mm or more and 2.0 m.
The reason for setting it below 0.1 mm is that if it is less than 0.1 mm, it will be difficult to form it into a pipe, and if it is larger than 2.0 mm, the formability and weldability will deteriorate, and furthermore, bulge deformation will occur during subsequent wire drawing. This is because it becomes easier to bend the wire, causing necking or disconnection of the wire. Forming copper tape into a pipe shape with an inner diameter that is 3.0 mm or more and 5.0 mm or less larger than the wire diameter of the steel wire is difficult because if the inner diameter is less than 3.0 mm, the core material will be affected by heat. This is because it causes variations in physical properties, increases the frequency of wire breakage during wire drawing, and if it exceeds 5.0 mm, it becomes difficult to eliminate the gap between the next core material and the pipe.

The reason why the process is performed to eliminate the gap between the core material and the pipe is that if the wire is directly drawn with a gap, the elongation of the copper pipe will be greater than that of the steel core material, and the cladding layer boundary will slip, causing the copper pipe to Because the chisel is processed, the copper may break or break. In particular, in the present invention, from the viewpoint of improving the fatigue characteristics of the finished wire, the surface has minute irregularities of 1 μm to 10 μm, so the frictional resistance between the copper pipe and the core steel wire is insufficient. This is because, depending on the wire drawing conditions, the cladding layer boundary may slip, so it is necessary to suppress the slippage by lightly pressing the copper against the steel wire by reducing the diameter of the pipe.

[0012] The reason why cold wire drawing is performed with a one-pass area reduction rate of 5% or more and 15% or less based on the wire diameter of the clad steel wire with no gaps is that if it is less than 5%, the wire will vibrate. If the ratio exceeds 15%, the frictional resistance between the cladding layer and the die increases, causing large friction on the surface layer. This is because the force exerted may cause slippage at the cladding layer boundary.

[0013] Furthermore, the reason why the wire is drawn so that the total area reduction rate is 50% or more is to strengthen the adhesion of the cladding layer and obtain the processing strain necessary to obtain sufficient fatigue properties.
This is because if it is less than 50%, the adhesion is insufficient and there is a risk of peeling of the cladding layer, resulting in poor fatigue properties.

[0014]

[Structure and Operation] The structure and operation of the present invention will be explained based on the embodiment shown in FIGS. 1 and 2. As shown in FIG. 1, the steel wire 2 drawn out from the feeding device 1 is fed into the shot blasting device 4 via the pinch rollers 3. The pinch rollers 3 straighten the steel wire and prevent the copper composite steel wire 10 from bending or vibrating until it is wound up by the winding machine 11. Therefore, if there is scale on the surface of the steel wire, the scale on the surface of the steel wire may be removed using a bending roller instead of the pinch roller 3 in a step before entering the shot blasting device 4.

In order to create the unevenness specified in the present invention by shot blasting, H
Shot grains having a particle size distribution of 10 μm to 100 μm with v500 or more may be projected at an appropriate pressure depending on the hardness of the steel wire surface. 1μ by shot blasting device 4
The steel wire 2 on which 40% or more of the surface area is provided with irregularities of 1 m or more and 10 μm or less enters the forming device 6 via the guide roller 5. A copper tape 13 supplied from a copper tape supply device 12 is fed into the forming device 6, and the copper tape is formed into a pipe shape around the steel wire 2 by this device. At this time, the inner diameter of the pipe-shaped copper tape is formed to be larger than the wire diameter of the steel wire 2 by 3.0 mm or more and 5.0 mm or less.

The butt portions of the copper tape 13 formed into a pipe shape by the forming device 6 are joined by the welding device 7. The forming device 6 and the welding device 7 produce a composite wire in which the core material is inside the pipe-shaped copper tape, and the swaging device 8 completely eliminates the gap between the steel wire 2, which is the core material, and the pipe-shaped copper tape. be done. The copper composite steel wire 10 in which the pipe-shaped copper tape is weakly composited in this way is once wound up by a winding device 11 via a guide roller 9. Here, the guide rollers 5 and 9 prevent the copper composite steel wire from bending or vibrating.

As shown in FIG. 2, a copper composite steel wire feeding device 1 is provided.
The copper clad steel wire 15 can be manufactured by drawing out the copper composite steel wire 10 from the wire 6, drawing it with the die 14, and winding it up with the winding device 17. As for the wire drawing conditions, the same die as for normal steel wire drawing is used, and the area reduction rate for one pass is 5 to 5.
If the wire is drawn at 10%, a normal wire drawing machine for steel wire can be used.

[0018] In this wire drawing process, if the irregularities on the surface of the steel wire are smaller than 1 μm, slippage will occur at the boundary between the copper pipe and the core material during wire drawing, and only the copper pipe will be pulled, resulting in the copper pipe breaking. . Moreover, if it is larger than 10 μm, small voids remain at the boundary between the copper and the core material of the copper-clad steel wire after wire drawing, which causes deterioration of fatigue properties. By the way, winding once after swaging is necessary when the processing speeds do not match between the composite process of welding and swaging and the next wire drawing process. It is also possible to directly draw the wire without winding it with the winder 11 within the range of conditions and wire drawing speed.

[0019]

[Example] The results of a manufacturing test for copper clad steel wire will be explained below. SWRH with a diameter of 2mm to 8mm for the core material
42A, SWRM8, and SWRH72A steel wire, if the area reduction rate after heat treatment of the core material exceeds 90%, 95
After heating at 0°C for 3 minutes, a patenting treatment of immersion in a 600°C lead bath for 1 minute or annealing at 950°C for 3 minutes was performed.

Since processing limits differ depending on the steel type of the core material, the finished wire diameter varies depending on the core material, but the adhesion process tends to be the same for all steel types. Tables 1, 2, and 3 show the manufacturing conditions, manufacturing status, and property test results when SWRH42A having intermediate hardness was used as the core material. Tests were conducted on copper tapes made of oxygen-free copper as cladding materials with thicknesses ranging from 0.05 mm to 3 mm. Oxygen-free copper was used as the copper tape material because it is necessary to have high conductivity depending on workability and application, so we selected one with as low an oxygen content as possible.

[0021] The abutting portions of the copper tape formed into a pipe shape were welded by TIG welding. Welding was carried out while keeping the oxygen partial pressure low in order to prevent oxide scale from forming in the welded area and impairing adhesion, and to prevent thin low-temperature scale from forming on the surface of the core steel wire. In addition, welding conditions are limited by the thickness of the copper tape and the difference between the diameter of the core material and the outside diameter of the pipe, so we adopted the optimal welding conditions according to the test.

For swaging, two to four stages of swaging devices were arranged in series depending on the difference between the diameter of the core material and the outside diameter of the pipe to reduce the area of the copper pipe. In some cases, it was possible to match the processing speed in the previous steps with the wire drawing speed in the next step, but for comparison purposes, in all tests, after swaging, the wire was wound in a winder, and then the wire drawing speed was Continuous processing was not performed. In the wire drawing process, the wire was drawn with a reduction in area per pass ranging from 3% to 30%, and the total reduction in area was from 30% to a maximum of 99%.

[0023] In the test, we investigated whether the desired characteristics were obtained by observing the manufacturing conditions such as forming, weldability, and wire drawing conditions, observing the boundary between copper and steel after wire drawing, and conducting fatigue tests. . As a result of research on the fatigue properties of many clad wires, it was found that the fatigue strength of copper-clad steel wires is degraded by cracks that exist at the interface between copper and steel and voids that occur due to the roughness of the interface. Therefore,
The fatigue properties of copper-clad steel wire can be evaluated by observing the boundary between copper and steel after wire drawing and confirming that there are no cracks or voids. Furthermore, for confirmation, regarding the copper clad steel wire finished to a wire diameter of 0.8 mm, the S-N curve was determined by Hunter fatigue test and the stress at the fatigue limit was compared. The fatigue limit was determined at a repetition rate of 107 times.

Table 1 (method of the present invention) and Table 2 (comparative method) show the manufacturing status under each manufacturing condition. As is clear from these tables, the method of the present invention can successfully process the wire up to the final diameter, whereas the comparative method, which differs from the conditions of the method of the present invention, can process the forming, welding, swaging, and wire drawing. Various problems occurred during the process, but No. 1 was able to process the wire to the final diameter. 22 and no. There were only 2 levels of 30.

Table 3 shows the fatigue limit of the sample processed to the final wire diameter and the results of microscopic observation of the boundary between copper and steel. No. of the method of the present invention. 5, 6 and comparative method No. As can be seen from 21 and 22, when the surface unevenness of the core steel wire becomes small, it tends to slip during the wire drawing process, and when it becomes large, voids remain at the boundary, which tends to lower the fatigue strength. Furthermore, corroborating the investigation of the relationship between fatigue properties and voids at the boundary, No.
．． No. 22 has deteriorated fatigue properties.

Since the fatigue properties cannot be simply compared when wire diameters are different, the Hunter fatigue test was carried out only on a 0.8 mm sample, but from the results of microscopic observation of the boundary, the No. 1 method of the present invention was tested. Comparative method No. 3, 4, 14, 15, and 16 had good fatigue properties, and microvoids were confirmed. It can be seen that No. 30 has low fatigue properties.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

[0030]

[Effects of the Invention] As described above, when the pipe cladding method according to the present invention is carried out in the production of copper-clad steel wire, slippage at the boundary between copper and steel can be suppressed, and the boundary can be formed by only cold working. Since the adhesion of the wire is improved and voids can be eliminated, it is possible to improve the fatigue characteristics of the copper-clad steel wire at the finished wire diameter.

Furthermore, since the copper clad steel wire obtained by the present invention uses high-strength steel for the core material, it is possible to provide a high-strength and highly corrosion-resistant wire by applying Zn plating, Ni plating, etc. By increasing the conductivity, it can also be used as a high-strength conductive wire.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the unevenness imparting and coating steps in the manufacturing process utilized in the examples of the present invention.

FIG. 2 is a schematic diagram of a wire drawing process.

[Explanation of symbols]

1 Supply device 2 Steel wire 3 Pinch roller 4 Shot blasting device 5 Guide roller 6 Forming device 7 Welding equipment 8 Swaging device 9 Guide roller 10 Composite steel wire 11 Winding device 12 Copper tape supply device 13 Copper tape 14 Dice 15 Copper clad steel wire 16 Supply device 17 Winding device

Claims (1)

[Claims] Claim 1: A copper wire made by using a steel wire as the core material, forming a copper tape around it into a pipe shape, TIG welding the butt portions, and then reducing the diameter of the pipe and the core material to join them. When manufacturing clad steel wire, the surface has a thickness of 1 μm or more.
The core material is a steel wire with a wire diameter of 3.0 mm or more and 5.5 mm or less, which has irregularities of μm or less on 40% or more of the surface area,
A copper tape with a thickness of 0.1 mm or more and 2.0 mm or less, placed vertically in the longitudinal direction of this core material, is placed 3.0 m from the wire diameter of the steel wire.
It is formed into a pipe shape with an inner diameter larger than m or more and less than 5.0 mm, and after welding the abutted parts, the gap between the core material and the pipe is eliminated, and the wire diameter of the clad steel wire with no gap is taken as a standard. A method for manufacturing a copper-clad steel wire, which comprises repeating cold drawing with a pass area reduction of 5% or more and 15% or less so that the total area reduction is 50% or more.