JP2915596B2 - Production method of extra fine wire - Google Patents

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 an ultrafine wire having excellent drawability.

2. Description of the Related Art In recent years, with the miniaturization and multifunctionality of electronic equipment, distribution lines used in such equipment have become increasingly thin, from ultra-fine wires of 50 μm or less to ultra-fine wires of 30 μm or less. Thinning is progressing to. For example, in the case of copper wire, these ultra-fine wires or ultra-fine wires (hereinafter referred to as ultra-fine wires) are obtained by cold drawing while subjecting a rough drawn wire manufactured by a continuous casting and rolling method such as SCR to annealing treatment in the middle. Manufacturing method. However, the aforementioned S
The ingot cast by the continuous casting and rolling method such as the CR method is 5000
mm ² scale for large ingot of a long process of up to the filament, particularly if small amounts, such as the production of alloy fine wire of high-mix is disadvantageous when viewed in cost, or such ingot Since the surface quality is poor, it is necessary to put a peeling step in the middle of the wire drawing process, resulting in poor productivity.

In view of the above, a method using an ingot of a small size of about 20 mmφ, and further, forming the small-sized ingot into a unidirectionally solidified structure or a directionally solidified structure having excellent workability, A method has been proposed in which cold working is performed at once to an ultrafine wire and annealing treatment in the middle is omitted. Since the ingot of this unidirectionally solidified structure or directional solidified structure is manufactured by performing heat extraction at the time of solidification directly through the produced ingot without using a mold, the surface quality is excellent, and therefore, a peeling step is performed on the way. It also has the advantage that it is unnecessary. However,
Even with the above-mentioned method of cold working a unidirectionally solidified structure or a directionally solidified ingot, there is a problem that if the diameter of the ultrafine wire is reduced, disconnection occurs frequently and productivity is significantly reduced.

[0003]

The present invention has been made in view of the above situation, and as a result of intensive research, as a result of cold working of a directional solidified structure or a directional solidified structure ingot, cracks occur at crystal grain boundaries. The inventors have found that the cracks cause disconnection in the subsequent step of cold expansion and contraction to an ultrafine wire, and have conducted further studies to complete the present invention. That is, the present invention is fine the ingot unidirectional solidification structure or directionally solidified structure by hot working
A method for producing an ultrafine wire, comprising forming a material for a fine wire having a recrystallized structure, and then cold-drawing the material for the fine wire. In the method of the present invention, the directionally solidified structure is a structure in which crystal grains 1 are grown in parallel with the longitudinal direction of the ingot as shown in a longitudinal sectional view of FIG. The lump 3 is manufactured by a method such as a hot mold continuous casting method or a Czochralski continuous casting method. When the ingot 3 of the unidirectionally solidified structure 2 is hot worked, the unidirectionally solidified structure 2 is formed.
Is changed to a fine recrystallized structure 4. On the other hand, the directional solidification structure is, as shown in FIG.
The crystal grains 1 grow obliquely from both sides of the ingot toward the center. The ingot 6 of the directional solidification structure 5 minimizes heat extraction from the mold, and the ingot is discharged from the mold. After
It is obtained by immediately forcibly cooling the ingot immediately, and is manufactured by weakening the cooling from the mold and increasing the secondary cooling by a usual horizontal continuous casting method or the like. Also in the case of this ingot 6, the directional solidification structure 5 is changed to a fine recrystallized structure 4 by performing hot working. In the method of the present invention, as a method of hot working a unidirectionally solidified structure or an ingot having a directional solidified structure, any working method such as rolling, extrusion, swager, drawing or the like is applied. In addition, as a method for processing the fine wire material after hot working into an extremely fine wire, a normal cold drawing method is used.

[0004]

According to the method of the present invention, since the ingot of a unidirectionally solidified structure or a directionally solidified structure is used, the surface quality is excellent and there is no need to perform a step such as peeling. Since the ingot is hot-worked, a fine wire material with a fine recrystallized structure can be obtained without causing grain boundary cracking, and ultra-fine wire with excellent wire drawing properties can be obtained by cold-drawing this fine wire material. Manufactured.

[0005]

The present invention will be described below in detail with reference to examples. Example 1 A 15 mmφ oxygen-free copper ingot having a unidirectional solidification structure or a directional solidification structure was manufactured by a heating mold continuous casting method or a horizontal continuous casting method.
The material was hot-rolled in a temperature range of 500 ° C. to obtain a material for a fine wire of 6 mmφ. Next, the above fine wire material is subjected to 3
Cold drawing was performed to a fine wire of 0 μm φ. Example 2 In Example 1, 0.6% of tin was added to copper instead of oxygen-free copper.
Using an added copper-tin alloy, this alloy is
An ultrafine wire having a diameter of 30 μm was manufactured in the same manner as in Example 1 except that hot rolling was performed in a temperature range of ° C. Comparative Example 1 An ultrafine wire having a diameter of 30 µm was produced in the same manner as in Example 1 or 2, except that each ingot produced in Example 1 or 2 was cold-rolled to obtain a material for a fine wire of 6 mmφ. . Comparative Example 2 Ingots of oxygen-free copper or copper-tin alloy were subjected to rolling by both hot and cold methods using polycrystalline ingots produced under ordinary conditions by a horizontal continuous casting method. An ultrafine wire of 30 μm φ was manufactured in the same manner as in Example 1 or 2, respectively. For each extra-fine wire produced in this way,
The extension dose per disconnection was examined. The results are shown in Table 1 together with the measurement results of surface defects. In addition, the rolling direction of the ingot having the directional solidification structure was set to the forward direction with respect to the growth direction of the crystal grains 1 as shown in FIG. Surface defects were measured by eddy current testing at 2 mmφ.

[0006]

[Table 1]

As is clear from Table 1, no surface defects were detected in the method products of the present invention (Nos.
The drawability at φ was also extremely excellent at 7 kg or more per disconnection. On the other hand, although Comparative Examples Nos. 5 to 8 had excellent surface quality, the ingot was cold-rolled, so that cracks were generated between the crystal grains and the drawability of the ultrafine wire was reduced. or
In Nos. 9 to 12, the ingot structure was polycrystalline, so that surface defects were generated, and the cold-worked material also had grain boundary cracks, so that the drawability was extremely reduced. In the above examples or comparative examples,
The reason that the unidirectional solidification structure ingot has better drawability than the directionally solidification structure ingot, and the oxygen-free copper ingot has better drawability than the copper-tin alloy is that the former has a difference in surface quality and the latter has a difference in deformation resistance. It is thought to be due to. Although copper and copper alloys have been described above, the same effects can be obtained by applying the method of the present invention to other metal materials such as aluminum.

[0008]

As described above, according to the method of the present invention, an extremely fine wire having good drawability can be obtained, and an industrially remarkable effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a unidirectionally solidified structure ingot used in the method of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of an embodiment of a directional solidification structure ingot used in the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal grain 2 Unidirectional solidification structure 3 Ingot of unidirectional solidification structure 4 Fine recrystallized structure 5 Directional solidification structure 6 Ingot of directional solidification structure

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C22F 1/08 B21C 1/00 B22D 27/04 H01B 1/02

Claims (1)

(57) [Claims] An ingot having a directionally solidified structure or a directionally solidified structure is hot-worked into a fine wire material having a fine recrystallized structure , and then the fine wire material is cold drawn. A method for producing an extra fine wire.