JPH10137836A - Peeling die for steel wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably extend a life by forming the peeling die for a steel wire with the steel of >=63 to <66 in HRC (Rockwell hardness, C scale) and hardening the surface coming into contact with a material to be worked with a TiN layer. SOLUTION: The steel wire 1, ground its surface layer with the peeling die 12 and introduced into a housing 11 evacuated into a vacuum, is straightened in a straight line with rolls 14a-14c and pulled out upward with pitch rolls 16. A composite wire 2 wherein copper or a copper alloy adhered is obtained in the meantime, however when an abnormality exists in the peeling die 12, molten copper is leaked from an inserting opening 23 and defective adhesion of copper to the steel wire 1 is generated. The base metal of the peeling die 12 is quenched at a lower temperature than the conventional temperature in the heat treatment, the hardness of the base metal is regulated to be >=63 to <66 in HRC (Rockwell hardness, C scale), and a TiN layer is formed on the ground surface of the steel wire 1 to harden. By this way, the life of the peeling die 12 is improved to be two times or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper-coated steel trolley wire suitable for supplying power to a high-speed railway train or a steel wire arranged in an apparatus for producing a copper-coated steel wire used as a wire for electric discharge machining. The present invention relates to a peeling die for steel wire, and more particularly to a peeling die for steel wire having excellent toughness.

[0002]

2. Description of the Related Art Various electric wires such as trolley wires and electric discharge machining wires are always required to have high strength and high electrical conductivity. Therefore, a composite wire in which a high-strength steel wire is used as a core wire, and high-conductivity copper or a copper alloy is coated as a coating material and bonded is developed and put into practical use. When joining copper and steel, if there is contamination on these joining surfaces, the joining strength is significantly reduced, and the strength of the composite wire is reduced,
Corrosion progresses to the part with poor bonding. In addition, if a flaw exists on the surface of the steel core wire, the strength of the composite wire is significantly reduced.

[0003] A method of manufacturing a copper-coated steel wire is to vertically attach a copper tape to a steel wire, wrap the steel wire with the copper tape, and then weld the copper tape at a butt end extending in the longitudinal direction of the steel wire. After that, there are a method of drawing and a method of plating copper around the steel wire by plating, and the conductivity of the composite material is 60% IACS.
As described above, as a method for thickly coating copper, a dip forming method in which a steel wire is immersed in molten copper is known (Japanese Patent Publication No. 2-11460). In these methods, there is a problem that if the surface of the steel wire is slightly contaminated, copper does not adhere to the steel wire.

[0004] In order to remove oxide scale, oil and other contamination and flaws on the surface of the steel wire, cleaning with acid and warm water, surface polishing with a shot blast, brush or the like, surface grinding with a peeling die, and the like are available. Among these, the method of obtaining a completely fresh steel wire surface with a peeling die can obtain the cleanest steel wire surface. For this reason, in the production of a copper-coated steel wire in which a steel wire is immersed in molten copper, the surface of the steel wire is cleaned using a non-lubricated peeling die.

[0005] However, in the production line of copper-coated steel wire, the feeding speed of the steel wire is 20 to 20 from the viewpoint of production efficiency.
It is set to 50 m / min, and it is necessary to continuously peel such a high-speed steel wire. For this reason, the wear of the peeling dies is extremely severe. In this way, if the peeling die is worn, the steel wire diameter changes, and the roughness of the steel wire surface after peeling increases, etc., so that the bonding strength between the steel wire core wire and the copper coating material decreases, and A copper-coated steel wire having the above performance cannot be obtained. Therefore, to prevent the wear of the peeling dies,
Prolonging the service life has an extremely large effect on increasing the production efficiency. Further, since the peeling dies are less likely to be worn, it becomes possible to use a high-strength steel wire that could not be used conventionally, so that the strength of the copper-coated steel wire can be improved.

Conventionally, such a peeling die is made of a high-carbon steel having a carbon content of about 1.0 to 1.2% by weight as a base material, and a portion in contact with a workpiece is made of TiN ( Those coated with titanium nitride) are used. The hardness of the base material is adjusted to HRC (Rockwell hardness, C scale) of 67 to 72 by heat treatment.

[0007]

However, using this peeling die, a steel wire having a diameter of 12 mm can be cut at 40 m / min.
When a copper-coated steel wire was manufactured by peeling, the life of the peeling die was about 5 to 10 hours, and thereafter, the state of adhesion of the copper to the steel wire deteriorated. As a result of examining the state of the peeling die after use, many cracks were present at the cutting edge of the die. As described above, the conventional peeling dies have a drawback that the service life is as short as about 5 to 10 hours.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a peeling die for a steel wire capable of significantly extending the life by increasing the toughness of a base material. .

[0009]

The steel wire peeling dies according to the present invention are made of HRC (Rockwell hardness, C scale).
Is formed of a steel material of 63 or more and less than 66, and a surface in contact with the workpiece is hardened by a TiN layer.

The inventor of the present application has focused on increasing the toughness of the base metal and has conducted intensive experiments and studies to extend the life of the peeling dies. It has been found that the intended purpose can be achieved by reducing the hardness.

The hardness of the base material of the conventional peeling dies is HR
C is 67 to 72. In the present invention, the HRC was adjusted to 63 or more and less than 66 by lowering the quenching temperature during the heat treatment. The peeling dies can be improved more than twice as much as before.

When the hardness of the base material is less than 63 in HRC,
Since the base material is too soft, adhesive wear between the base material and the workpiece increases. On the other hand, if the hardness of the base material is 66 or more in terms of HRC, the life is the same as that of the conventional product. Therefore, in the present invention, by reducing the hardness of the base material from that of the conventional peeling dies, the toughness is increased, the time required for cracks to be formed is increased, and the life is extended.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, a so-called dip forming apparatus equipped with a peeling die 12 according to an embodiment of the present invention will be described with reference to FIG. In this dip forming apparatus, a steel wire supply device 10 is provided.
A coating device 20 made of copper or a copper alloy is disposed above the above.

First, as shown in FIG. 1, a steel wire 1 is introduced into a housing 11 evacuated while a surface layer thereof is continuously ground by a peeling die 12. This steel wire 1
Passes through the peeling die 12 in the direction of the arrow in FIG. 1 at a supply speed of, for example, 40 m / min. Here peeling dice 1
2, the surface of the steel wire 1 is ground, and the steel wire 1 having a clean surface is wound around the capstan 13 to change its traveling direction upward. In this case, the steel wire 1 is bent by the capstan 13, and the steel wire 1 is straightened by the rollers 14 a, 14 b, and 14 c of the straightening device 14.

Next, the steel wire 1 is pulled upward by the pinch roll 16 and introduced into the crucible 22 from an insertion port 23 provided at the bottom of the crucible 22 of the coating apparatus 20.
Then, the steel wire 1 is pulled upward in the crucible 22, during which the molten metal 21 in the crucible 22 adheres to the steel wire 1. Then, the adhered molten metal 21 solidifies to obtain a composite wire 2 in which copper or a copper alloy is attached around the steel wire 1.

The composite wire 2 is then rolled by a hot rolling device, whereby the steel wire of the core material and the copper or copper alloy region of the coating material are metal-bonded, and FIG. As shown, the coating material 4 is firmly attached to the core material 3. In the composite wire thus manufactured, diffusion of atoms occurs at the interface between the steel wire and the copper or copper alloy region, and the bonding is extremely strong. In this case, if there is an abnormality in the peeling die, molten copper leaks from the insertion port 23 or poor adhesion of copper to the steel wire occurs.

In the present embodiment, as the peeling die 12 for steel wire, the hardness of the base material is 63 or more by HRC and 6 or more.
Use one adjusted to less than 6. This is not adjusted by adjusting the composition of the base material, but by adjusting the heat treatment conditions. That is, the heat treatment of the base material is adjusted to 63 or more and less than 66 in HRC (Rockwell hardness, C scale) by lowering the quenching temperature during the heat treatment than before. Thereafter, a TiN layer is formed on the surface in contact with the workpiece, and a hardening process is performed. The life of the peeling die 12 manufactured in this manner is more than double that of the conventional one.

[0018]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. A copper-coated steel wire was manufactured by the dip forming apparatus shown in FIG. In this embodiment,
The feeding speed of the steel wire 1 is 40 m / min, the diameter of the steel wire before passing through the peeling die is 12.3 mm, and the hole diameter of the peeling die is 1 mm.
2.0 mm. In addition, the comparative example was performed under the same manufacturing conditions.

The peeling die 12 of the embodiment used had a base material hardness of 64 in terms of HRC (Rockwell hardness, C scale) and was coated on its surface with a TiN layer.

On the other hand, in the case of the comparative example, the hardness HRC of the base material of the peeling die 12 and the type of the surface coating layer were 67 and TiN in Comparative Example 1, and 62 in Comparative Example 2 respectively.
And TiN, and Comparative Example 3 was 70 and TiC, respectively.

Table 1 below shows the judgment life and judgment results of the respective examples and comparative examples.

[0022]

[Table 1]

As is apparent from Table 1 above, the hardness of the base material of the steel wire peeling die of this embodiment is 64 in HRC (Rockwell hardness, C scale), and Ti
By providing the N coating layer, the life of the peeling dies for steel wire is 15 hours, which is 2 hours of the conventional peeling dies.
The service life was significantly prolonged compared to ~ 8 hours.

[0024]

As described above, the steel wire peeling dies according to the present invention are formed of a steel material having an HRC (Rockwell hardness, C scale) of 63 or more and less than 66, and come into contact with the workpiece. Since the surface is hardened by the TiN layer, the life can be significantly extended as compared with a conventional peeling die.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a dip forming apparatus provided with a peeling die according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a copper-coated steel wire.

[Description of Signs] 1; steel wire 2; composite wire 3; core material 4; coating material 12; peeling die 13; capstan 14;

Claims (1)

[Claims] 1. A steel wire characterized by being formed of a steel material having an HRC (Rockwell hardness, C scale) of 63 or more and less than 66, and a surface in contact with a workpiece is hardened by a TiN layer. For peeling dies.