JPH09150323A - Electric discharge machining electrode wire and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both characteristics of high tensile strength as well as high conductivity which cap attain the higher accuracy and higher speediness of electric discharge machining. SOLUTION: A core material 2 is enveloped by an Nb/Cu two-phase dispersion strengthening compound unit 3 comprising an Nb/Cu layered compound unit 3a superposing a sheet material 6 of Nb alloy or a sheet material 7 of Cu or Cu alloy closely wound, this Nb/Cu two-phase dispersion strengthening compound unit 3 is enveloped by a Cu layer 14 consisting of Cu or Cu alloy, the Cu layer 4 is enveloped by a Cu-Zn alloy layer 5. Ordinary temperature tensile strength of the core material in an annealed condition is set to 10kgf/ mm<2> or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining electrode wire used in wire electric discharge machining and a manufacturing method thereof, and more particularly to an electric discharge machining electrode wire excellent in tensile strength and conductivity and a manufacturing method thereof. is there.

[0002]

2. Description of the Related Art Wire electric discharge machining is a machining method for fusing a work piece to a predetermined size by an electric discharge phenomenon between a traveling wire electrode wire and the work piece, which is difficult to mechanically cut or cut. Widely used in the processing of molds and the like. In the recent field of die processing, there is a strong demand for higher precision and higher speed. With a diameter of 0.1 mm or less, 150 kgf
/ Mm ² (about 1,500 MPa) or higher high tensile strength, 2
The appearance of ultrafine electrode wires having high conductivity characteristics of 0% IACS or higher is awaited.

As this type of electrode wire, a W single electrode wire having a high tensile strength has been conventionally used. The W electrode wire is
Tensile strength is about 400kgf / mm ² (about 4,000MP
It has about 4 times the strength of a) and general-purpose brass electrode wire. For this reason, the W electrode wire has a wire diameter of 0.1 m for higher accuracy.
Even if the thickness is extremely thinned to m or less, it is possible to apply a sufficient tension that does not cause vibration of the electrode wire, which causes a reduction in processing accuracy. However, considering that W itself is a kind of rare metal, is a difficult-to-machine material, and the electrode wire is a consumable item, an ultrafine W electrode wire using W as an electrode wire is very expensive. It becomes a thing. Furthermore, W
When the electrode wire is used, the strength is too high, so that the delivery reel for applying a voltage to the electrode wire and the take-up reel are heavily worn, and an unstable discharge phenomenon is likely to occur due to a change in contact resistance or the like.

[0004]

In order to improve the drawbacks of these W electrode wires, brass (Cu-35%) which is a general-purpose electrode wire is used.
A composite electrode wire having a tensile strength intermediate between that of the (Zn) electrode wire and the W electrode wire and having a Cu—Zn alloy layer coated around the high-strength steel wire has been developed as an electrode wire for high-precision machining (for example, JP-A-56-126528).

As shown in FIG. 3, this composite electrode wire 11
Uses a high tensile strength steel 12 which is a tension member as a core portion, and surrounds the core portion, and a Cu—Zn alloy layer 13 is arranged. As a result, the composite electrode wire 11 has a tensile strength of about 15
0 to 200 kgf / mm ² (about 1,500 to 2,000
(MPa), a sufficient tension can be applied for high-precision machining, and wear on the feed reel and the take-up reel can be reduced. That is, the composite electrode wire 11 has an appropriate tensile strength and can be supplied at a relatively low cost.

However, since the composite electrode wire 11 has the Cu-Zn alloy layer 13 having a low tensile strength as the outer layer, the composite electrode wire 11 must have sufficient tensile strength to be secured. The proportion of the high tensile strength steel 12 in the core part of 1 must be increased. However, in this case, since the electrical conductivity of the high tensile strength steel 12 is only about 10% IACS, the electrical conductivity of the composite electrode wire 11 is lowered,
There is a big problem that it is difficult to increase the electric discharge current which is indispensable for increasing the speed of electric discharge machining.

Therefore, the present invention solves the above-mentioned problems and further improves the precision and speed of electric discharge machining, and has the characteristics of high tensile strength and high conductivity for electric discharge machining. An object is to provide an electrode wire and a manufacturing method thereof.

[0008]

In order to solve the above-mentioned problems, the invention of claim 1 is such that the core material is Nb in which a sheet material of Nb or Nb alloy and a sheet material of Cu or Cu alloy are superposed and tightly wound. Surrounded by a Nb / Cu2 phase dispersion strengthened composite consisting of a Cu / Cu laminated composite, and the Nb / Cu2 phase dispersion strengthened composite surrounded by a Cu layer composed of Cu or a Cu alloy,
It is an electrode wire for electric discharge machining in which the Cu layer is surrounded by a Cu-Zn alloy layer.

The invention of claim 2 is the electrode wire for electrical discharge machining according to claim 1, wherein the core material is made of a metal having a tensile strength at room temperature of 10 kgf / mm ² or more in an annealed state.

In the invention of claim 3, the core material is Nb or N
Nb / Cu comprising a Nb / Cu laminated composite in which a sheet material of b alloy and a sheet material of Cu or Cu alloy are superposed and tightly wound.
A discharge machining electrode surrounded by a Cu2 phase dispersion strengthened composite, the Nb / Cu2 phase dispersion strengthened composite surrounded by a Cu layer made of Cu or a Cu alloy, and the Cu layer surrounded by a Cu-Zn alloy layer. This is a method for manufacturing an electrode wire for electric discharge machining, which is manufactured by subjecting a wire to surface-reduction processing such as extrusion and drawing.

According to a fourth aspect of the invention, the electrode for electric discharge machining according to the third aspect is characterized in that the plate thickness ratio between the sheet material of Nb or Nb alloy and the sheet material of Cu or Cu alloy is 1: 9 to 9: 1. It is a method of manufacturing a wire.

The invention of claim 5 uses a hydrostatic extrusion method or a lubricating oil extrusion method as the extrusion method.
It is a manufacturing method of the electrode wire for electric discharge machining described.

The invention of claim 6 is the method of manufacturing an electrode wire for electric discharge machining according to claim 3, wherein the diameter of the electrode wire for electric discharge machining is 0.1 mm or less.

The invention according to claim 7 is the method for producing an electrode wire for electric discharge machining according to claim 3, wherein the core material is made of a metal having a tensile strength at room temperature of 10 kgf / mm ² or more in an annealed state.

The reasons for limiting the above composition range will be described below.

The reason for limiting the plate thickness ratio between the sheet material of Nb or Nb alloy and the sheet material of Cu or Cu alloy to the range of 1: 9 to 9: 1 is that the sheet thickness of the sheet material of Nb or Nb alloy is This is because if the thickness is less than 1/9 of the sheet thickness of the Cu or Cu alloy sheet material, sufficient tensile strength cannot be obtained. vice versa,
The sheet thickness of Nb or Nb alloy sheet material is Cu or Cu
This is because if it exceeds 9 times the plate thickness of the alloy sheet material, the electrical conductivity will drop significantly.

According to the present invention, a sheet material of Nb or Nb alloy and Cu or Cu are provided around the core material.
An Nb / Cu two-phase dispersion-strengthened composite body composed of an Nb / Cu laminated composite body in which an alloy sheet material is overlapped and tightly wound is arranged, and a Cu layer composed of Cu or a Cu alloy is provided around the composite body.
Further, since the Cu-Zn alloy layer is arranged around the electrode layer, it is possible to obtain an electrode wire for electric discharge machining which has excellent electric discharge machinability as well as high tensile strength and high conductivity characteristics.

In the plastic working of the composite material, if the difference in deformation resistance between the constituent materials is too large, a plastic instability phenomenon called a necking phenomenon occurs, and troubles such as wire breakage easily occur. In the present invention, since the strength of the Nb / Cu2 phase dispersion strengthened composite, that is, the deformation resistance is high, it is necessary to use a material having a high deformation resistance as the core material in order to prevent the occurrence of the plastic instability phenomenon. . 10 kgf in the annealed state
By using a metal having / mm ² or more at room temperature tensile strength, and strain hardening by reduction process at ambient temperature, as a result, it is possible to prevent occurrence of plastic instability phenomenon, maintaining good reduction process of it can.

[0019]

Embodiments of the present invention will be described below.

As shown in FIG. 1, the electric discharge machining electrode wire 1 of the present invention comprises four layers of a core material 2, a Nb / Cu2 phase dispersion strengthened composite body 3, a Cu layer 4 and a Cu—Zn alloy layer 5. It consists of

The core material 2 is arranged to be a core of Nb or Nb alloy sheet material (hereinafter referred to as Nb sheet) 6 and Cu or Cu alloy sheet material (hereinafter referred to as Cu sheet) 7, and is subjected to electric discharge machining. Nb or N at the center of the electrode wire 1 for
It is formed of a b-alloy in a cylindrical shape having a predetermined length and diameter.

The Nb / Cu2 phase dispersion reinforced composite body 3 is arranged so as to have good high tensile strength and high conductivity characteristics, and the Nb sheet 6 and the Cu sheet 7 are stacked and
It is composed of a Nb / Cu laminated composite body 3a which is closely wound with the b-sheet 6 inside, and is provided so as to surround the core material 2.

The Cu layer 4 is the Cu-Z provided on the outermost layer.
Between the two phases of Zn in the n alloy layer 5 and the Nb / Cu2 phase dispersion strengthening type composite body 3, it is arranged as a reaction preventing layer for preventing generation of Nb-Zn based intermetallic compound having no ductility.
Other than Cu, it is a material that does not or does not easily form an intermetallic compound having no ductility with the constituent elements of the Nb / Cu2 phase dispersion strengthened composite 3 and the element of the Cu-Zn alloy layer 5 of the outermost layer, and is cold. It may be replaced with a metal material capable of surface reduction with a cross-section reduction rate of 50% or more. The production of Nb-Zn-based intermetallic compounds can be reduced depending on the production conditions, and in that case, the Cu layer may be omitted.

The Cu—Zn alloy layer 5 is arranged to improve the electric discharge machinability, and is provided so as to surround the Cu layer 4. As the Cu-Zn alloy layer 5, Z having good electric discharge machining characteristics
Except for Cu-Zn alloys with n added in the range of 10 to 50 wt%, replace with a composite material in which Zn or a Zn-based alloy is coated around a metal material that can be cold-worked with a surface reduction of 50% or more. May be.

Next, the method of the present invention will be described.

A Cu sheet 7 having a length longer than that of the Nb sheet 6 is superposed on the Nb sheet 6. Among the overlapped sheets, the Nb sheet 6 is placed inside, and the Nb sheet 6 is tightly wound around a cylindrical core material 2 made of Nb or an Nb alloy and having a predetermined length and diameter. Since the length of the Cu sheet 7 is longer than the length of the Nb sheet 6, the extra length portion 7a of the Cu sheet 7 is generated. The extra length portion 7a of the Cu sheet 7 is further tightly wound to form the Cu layer 4. The Cu layer 4 may be formed by using a Cu pipe.

The composite consisting of these three layers is inserted into a Cu-Zn tube. Then, a sealing tool is attached to the opening of the Cu—Zn tube to form an extruded billet. After the extruded billet is extruded (hydrostatic extrusion method, lubrication extrusion method, etc.), diameter reduction processing is performed by surface reduction processing such as die drawing to obtain a wire material, and the electric discharge machining electrode wire 1 is obtained.

Next, the mechanism by which the Nb / Cu laminated composite in which the Nb sheet and the Cu sheet are superposed and tightly wound into the Nb / Cu two-phase dispersion strengthened composite having high tensile strength properties will be described.

In the Nb / Cu laminated composite 3a, the Nb layer and the Cu layer are layered at the time of formation, but the layered structure is destroyed by the subsequent surface-reduction processing such as extrusion and wire drawing, and the final structure is obtained. Then, one of the layers changes into a dispersed structure with a dispersed phase.

In the processing region where the layered structure does not collapse, the composite rule is established and the tensile strength of the Nb / Cu laminated composite 3a itself is low, so it is difficult to apply it as a strength member of the electric discharge machining electrode wire 1. . On the other hand, the composite rule cannot be applied in the processed region where the layered structure collapses to become a dispersed structure. As a result, Nb / Cu2 phase dispersion strengthened composite 3
Is up to 250 kgf / mm ² (about 2,500 MPa)
It is possible to obtain a tensile strength of up to 10 and a composite body that satisfies the characteristics required for the strength member of the electric discharge machining electrode wire 1 is obtained. Further, by using Cu as one of the constituent materials of the Nb / Cu2 phase dispersion strengthened composite 3, the Nb / Cu2 phase dispersion strengthened composite 3 has high conductivity characteristics even after the dispersion structure is formed. .

Next, examples of the present invention will be described.

FIG. 3 is a diagram showing a method for laminating the Nb / Cu laminated composite of the present invention.

Nb / C of the composite electrode wire produced in this example
Table 1 shows the specifications of the u laminated composite.

[0034]

[Table 1]

(Example 1) Nb sheet having a thickness of 0.22 mm, a length of 1730 mm and a width of 100 mm, a thickness of 0.025 mm and a length of 2 was used as a core of industrial pure Nb having a diameter of 6 mm.
Cu sheets having a width of 862 mm and a width of 100 mm were laminated in a sushi roll shape to form a laminated composite. This laminated composite has an outer diameter of 2
Cu-35 wt% Zn with 7.1 mm and inner diameter of 25.1 mm
It was inserted into an alloy (JIS C2700) pipe, and a sealing tool was attached to the opening of the pipe to form a billet for hydrostatic extrusion. The volume ratio of Nb in this billet is about 5
%, The volume ratio of the Nb / Cu laminated composite was about 75%, the volume ratio of the Cu layer was about 5%, and the volume ratio of the Cu—Zn layer was about 15%. After isostatic pressing, a diameter reduction process was performed by drawing a die to prepare linear 0.1 mm, 0.07 mm, and 0.05 mm ultrafine composite electrode wires.

Example 2 Nb sheet having a thickness of 0.15 mm, a length of 2425 mm and a width of 100 mm, a thickness of 0.025 mm and a length of 3 was used as a core of industrial pure Nb having a diameter of 6 mm.
An ultrafine composite electrode wire was produced in the same manner as in Example 1 by using a Cu sheet having a width of 555 mm and a width of 100 mm.

(Embodiment 3) Nb sheet having a thickness of 0.05 mm, a length of 5655 mm, and a width of 100 mm, a thickness of 0.025 mm, and a length of 6 are used with a core of industrial pure Nb having a diameter of 6 mm.
An ultrafine composite electrode wire was produced in the same manner as in Example 1 using a Cu sheet having a width of 785 mm and a width of 100 mm.

(Embodiment 4) Nb sheet having a thickness of 0.05 mm, a length of 4240 mm and a width of 100 mm, a pure Nb for industrial use having a diameter of 6 mm as a winding core, a thickness of 0.05 mm and a length of 48.
An ultrafine composite electrode wire was produced in the same manner as in Example 1 using a Cu sheet having a width of 10 mm and a width of 100 mm.

(Embodiment 5) Nb sheet having a thickness of 0.05 mm, a length of 2825 mm and a width of 100 mm, a thickness of 0.1 mm and a length of 311 is used as a core of industrial pure Nb having a diameter of 6 mm.
Example 1 using a Cu sheet of 0 mm and width of 100 mm
An ultrafine composite electrode wire was prepared in the same manner as in.

(Embodiment 6) With a core of industrial pure Nb having a diameter of 6 mm, a thickness of 0.05 mm, a length of 850 mm and a width of 1
00mm Nb sheet, thickness 0.45mm, length 910
An ultrafine composite electrode wire was produced in the same manner as in Example 1 using a Cu sheet having a size of 100 mm and a width of 100 mm.

Here, the length of the Cu sheet is longer than that of the Nb sheet in each of the examples.
This is because the end portions of the sheet are aligned and wound around the core to form the Cu layer in the extra length portion of the Cu sheet.

Table 2 shows the tensile strength and conductivity characteristics obtained for each wire diameter in each example.

[0043]

[Table 2]

As shown in Table 2, Example 3 (Nb: Cu)
= 2: 1), the tensile strength shows the highest value, and Nb /
The tensile strength is reduced as the composition of Nb and Cu in the Cu2 phase dispersion strengthened composite becomes closer to the Nb rich side and the Cu rich side. Nevertheless, 150k in each example
A tensile strength of gf / mm ² (about 1,500 MPa) or more was obtained.

Φ0.1 mm, φ0.07 mm, φ
When each electrode wire of 0.05 mm is examined, the tensile strength is improved as the wire diameter becomes smaller. this is,
It is shown that the finer the wire diameter is, the better the tissue is dispersed.

The conductivity characteristics were improved as the composition of Nb and Cu in the Nb / Cu two-phase dispersion strengthened composite became closer to the Cu-rich side, and showed the highest value in Example 6. Nevertheless, Example 1 (Nb: Cu =
13.5 even when the wire diameter of 9: 1) is 0.05 mm
It has a conductivity of% IACS, and is more than the conductivity characteristic (about 10% IACS) in the composite electrode wire of the prior art.
It can be seen that it shows excellent characteristics.

Φ0.1 mm, φ0.07 mm, φ
When examining each electrode wire of 0.05 mm, the conductivity decreases as the wire diameter becomes smaller. This indicates that the finer the electrode diameter, the finer the distribution of the structure, and the smaller the area of the Cu simple structure having high conductivity.

[0048]

In summary, according to the present invention, Nb or Nb alloy sheet material and C are used as the strength members of the electrode wire.
Nb that is tightly wound by stacking u or Cu alloy sheet material
Since the Nb / Cu2 phase dispersion strengthened composite having the / Cu laminated composite as a base material is arranged, it is possible to obtain an excellent effect that an electrode wire for electric discharge machining having high tensile strength and high conductivity can be obtained. Demonstrate.

[Brief description of the drawings]

FIG. 1 is a view showing a cross section of an electric discharge machining electrode wire of the present invention.

FIG. 2 is a diagram showing a method for laminating a Nb / Cu2 phase dispersion strengthened composite of the present invention.

FIG. 3 is a view showing a cross section of a conventional electric discharge machining electrode wire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrode wire for electrical discharge machining 2 Core material 3 Nb / Cu2 phase dispersion strengthening type composite body 3a Nb / Cu laminated composite body 4 Cu layer 5 Cu-Zn alloy layer 6 Nb sheet (sheet material of Nb or Nb alloy) 7 Cu sheet (Cu or Cu alloy sheet material)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazutaka Sasaki 3550 Kidayomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Tsuchiura Plant (72) Inventor Kenichi Kikuchi 3550 Kidayomachi, Tsuchiura City, Ibaraki Hitachi Cable Shares (72) Inventor Takamitsu Kimura 4-10-1 Kawajiri-cho, Hitachi-shi, Ibaraki Hitachi Cable Ltd. Toyoura factory

Claims (7)

[Claims] 1. A core material is surrounded by a Nb / Cu two-phase dispersion strengthening type composite body composed of an Nb / Cu laminated composite body in which a sheet material of Nb or Nb alloy and a sheet material of Cu or Cu alloy are superposed and tightly wound. Then, the Nb / Cu2 phase dispersion strengthened composite is surrounded by a Cu layer made of Cu or a Cu alloy.
An electrode wire for electric discharge machining, characterized in that the layer is surrounded by a Cu-Zn alloy layer. 2. The core material is 10 kgf / m in an annealed state.
A metal having a tensile strength at room temperature of m ² or more.
The electrode wire for electric discharge machining described. 3. A Nb / Cu two-phase dispersion-strengthened composite body composed of a Nb / Cu laminated composite body in which a sheet material of Nb or Nb alloy and a sheet material of Cu or Cu alloy are superposed and densely wound on a core material. Then, the Nb / Cu2 phase dispersion strengthened composite is surrounded by a Cu layer made of Cu or a Cu alloy.
A method for producing an electrode wire for electric discharge machining, characterized in that an electrode wire for electric discharge machining, the layer of which is surrounded by a Cu-Zn alloy layer, is produced by surface-reduction processing such as extrusion and drawing. 4. The Nb or Nb alloy sheet material and C
The plate thickness ratio of the u or Cu alloy sheet material is 1: 9 to 9:
The method for producing an electrode wire for electric discharge machining according to claim 3, wherein 5. The method for producing an electrode wire for electric discharge machining according to claim 3, wherein a hydrostatic extrusion method or a lubricating oil extrusion method is used as the extrusion method. 6. The wire diameter of the electric discharge machining electrode wire is 0.1 m.
The method for producing an electrode wire for electric discharge machining according to claim 3, wherein the length is m or less. 7. The core material is 10 kgf / m in an annealed state.
A metal having a normal temperature tensile strength of m ² or more.
A method for producing the electrode wire for electric discharge machining as described above.