JPH11319933A - Steel wire drawing method and steel wire - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for drawing a high strength and high ductility wire. [Structure] In drawing using a die, wire drawing is performed using three dies successively, and the three dies at this time are reduced from A, B, C to the material entering side, respectively. A wire drawing method characterized in that the area ratios Ra, Rb and Rc satisfy the following. Ra + Rb + Rc: 40% or less Rb / Ra is 2 or more Rb / Rc is 2 or more

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire drawing method used in the manufacture of steel wires such as tire cords, belt cords, hose wires, ACSR wires, control cables, PWS wires, and PC wires.

[0002]

2. Description of the Related Art In general, ultra-fine high-carbon steel wires drawn such as steel cords are usually hot-rolled as necessary, and then cooled and adjusted to a diameter of 4.0 to 5.5 mm. A final patenting process is performed, followed by a brass plating process and a final wet drawing process. Many of such ultra-fine steel wires are used as steel cords after being subjected to stranded wire processing such as double twisting or five twisting. Steel cords must have the following properties: 1) higher strength, 2) excellent high-speed drawability, 3) excellent fatigue properties, 4) excellent high-speed stranded wire properties, etc. No.

[0003] For this reason, high-quality steel materials have been conventionally developed in response to requests. For example, JP-A-60-2048
No. 65 discloses that the Mn content is regulated to less than 0.3% to suppress the generation of a supercooled structure after lead patenting,
By controlling the amount of elements such as i and Mn, high-strength and high tough ductile ultra-fine wires and high-carbon steel wires for steel cords with less breakage during stranded wire are disclosed,
JP-A-63-24046 discloses that the content of Si is 1.
A high toughness and high ductility ultrafine wire is disclosed in which the tensile strength of the lead patenting material is increased by setting it to at least 00% to reduce the drawing ratio.

[0004]

SUMMARY OF THE INVENTION The present invention provides a method for producing a steel wire having higher strength and excellent twist characteristics without changing the steel used conventionally.

[0005]

The easiest way to improve the strength of a drawn wire is to increase the amount of wire drawing, but there is a limit because increasing the strength reduces ductility. In order to improve this limit, as the strength increases, there are problems such as deterioration of the lubrication state and increase in residual stress due to non-uniform processing. Therefore, a wire drawing method for suppressing these has been required.

For this purpose, a plurality of continuous dies are conventionally arranged without a drive function, and the ratio of the reduced area in each die is changed. The present inventors have found that it is possible to positively change the lubrication state and the processing state by doing this.

[0007] Specifically, three dies are used consecutively. The main purpose of each die is to improve residual stress and lubrication condition. The second is the main surface reduction processing, and the third is the uniformization of the processing state and the improvement of the residual stress.

[0008] Then, the dies are moved from the material entry side to A,
Ra, Rb, Rc, A
When the area reduction rate of the entire die from R to C is defined as Rabc, a wire drawing method satisfying the following conditions is performed.

(A) Rabc: 40% or less (b) Rb / Ra: 2 or more (c) Rb / Rc: 2 or more The reasons for limiting the above conditions will be described below. First, with respect to the total area reduction rate Rabc of all three dies under the condition (a),
If it is 40% or more, wire drawing cannot be performed, so the upper limit is set to 40%.

Next, condition (b) is adjusted so that Rb / Ra becomes 2 or more. If the ratio is less than 2, it is difficult to improve the lubrication state, and the residual stress in the longitudinal direction of the surface of the drawn wire is not in a good compression state. In order to obtain a more stable effect, it is desirable that Rb / Ra is 5 or more.

The condition (c) is adjusted so that Rb / Rc becomes 2 or more. If it is less than 2, the working state is not uniform, and the residual stress of the drawn wire is not in a good state, so it is set to 2 or more. In order to obtain a more stable effect, Rb / Rc is desirably 5 or more.

[0012] Such a drawing method is hereinafter referred to as triple die drawing. Further, as a feature of the wire obtained by the above-described drawing method, the residual stress in the length direction of the wire is adjusted to the compression side at least at a depth of 0.2 r (r: radius of the wire) from the surface layer toward the central axis. Have been. Alternatively, or by improving the lubrication condition, the surface Rmax is reduced to 10 μm.
m or less.

The most effective effect of wire drawing using three dies is applied to the finishing die portion of wire drawing. In order to increase this effect, the triple-die drawing of the present invention may be applied to all the dies, or the triple-die drawing may be applied to several dies which are traced back from the finishing dies as necessary.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The effects of the present invention will be described below based on embodiments. A 5.5 mm wire of JIS SWRS82A was made a 1.85 mm wire by wire drawing and intermediate patenting. The wire was subjected to a patenting process to obtain a steel wire having a pearlite structure. Table 1 shows the mechanical properties at this time.

[0015]

[Table 1] Mechanical properties of patenting wire

This wire was subjected to a brass plating treatment to obtain a 0.3 mm wire by continuous drawing. Table 2 shows the mechanical properties when the triple wire drawing method was used for the finishing dies, when it was used at three locations from the finish, and when normal wire drawing was performed for comparison.

[0017]

[Table 2] Mechanical properties of wire after drawing

As shown in Table 2, while the tensile strength does not change much, the steel wire of the present invention shows excellent twisting characteristics. Table 3 shows the results of confirming whether the surface roughness and the residual stress were compressed to 0.2r. In the table, items of residual stress are indicated by ○ when compression is performed up to the portion of 0.2 r, and x when not compressed. The surface roughness was measured at any point in the circumferential direction. The residual stress is X
It was measured by a line diffraction method.

[0019]

[Table 3] Roughness and residual stress of drawn wire

It can be seen that the steel wire produced by the method of the present invention has a small surface roughness and the residual stress is adjusted to the compression side.

[0021]

According to the present invention, a wire having high strength and excellent ductility can be easily obtained.

Claims (4)

[Claims] In a method for drawing and drawing a steel wire using a die, wire drawing is performed using three consecutive dies, and the surface reduction rate of the three dies at that time is as follows. A method for drawing a steel wire. (A) Rabc: 40% or less (b) Rb / Ra: 2 or more (c) Rb / Rc: 2 or more However, Rabc; Reduction rate of all three dies Ra, Rb, Rc; A, B, C from the side
The area reduction rate of each time. 2. The steel wire produced by the method for drawing a steel wire according to claim 1, wherein the residual stress is on the compression side at least at a depth of 0.2 r from the surface layer of the steel wire. Here, r: radius of the wire. 3. The steel wire having a surface roughness Rmax of 10 μm.
A steel wire manufactured by the method for drawing a steel wire according to claim 1, wherein: 4. The steel wire according to claim 1, wherein the residual stress is on the compression side at least at a depth of 0.2 r from the surface layer of the steel wire, and Rmax in the surface roughness of the steel wire is 10 μm or less. Steel wire manufactured by the method of drawing steel wire.