JP3332197B2 - Method of manufacturing electrode wire for electric discharge machining - 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 electrode wire for electric discharge machining used for wire electric discharge machining, and more particularly to a method for producing an electrode wire for electric discharge machining using a copper alloy.

[0002]

2. Description of the Related Art In wire electric discharge machining, a thin metal wire (electrode wire for electric discharge machining) serving as an electrode wire is wound up and three-dimensionally fed to a work to be wound. In this method, a workpiece is blown while performing electric discharge to perform a saw-tooth processing, and a three-dimensional product can be created with high accuracy without using an electrode having a specific shape. Particularly, since a hard metal or the like that is difficult to machine can be machined with high precision, the practical range has been expanding in recent years.

Conventionally used electrode wires for electrical discharge machining include, for example, Cu-35 wt% Zn brass electrode wires. "Journal of Copper and Copper Technology", 26, (1987) P181
(Presenters: Orimo, Ishibashi, Okuno) It is known that the higher the Zn concentration in the composition, the higher the processing speed can be. However, the amount of Zn (zinc) is 40% by weight.
If β exceeds, a β phase is formed, so that wire drawing cannot be performed by cold rolling. Thus, due to the problem of workability, in the electrode wire for electric discharge machining containing Zn, Cu-35% by weight Z
An n-brass wire is considered a standard product.

However, since an improvement in the processing speed leads to an improvement in productivity, various proposals have been made to increase the processing speed while containing Zn. For example, an electrode wire whose core material is coated with an alloy containing 50% or more of Zn (Japanese Patent Publication No.
-5648). Further, as an electrode wire for forming a coating layer on a core material, for example, Zn (or Zn
Alloy wire) in which a Zn-enriched layer is formed on the surface by immersion annealing (JP-A-62-218026) and a composite electrode wire in which a steel wire is coated with a metal having good electrical conductivity (Japanese Patent Publication No. 57-57).
No. 211), a predetermined thickness of Cu-
An electrode wire in which a Zn alloy layer is provided, and a Zn layer having a predetermined thickness is further provided on the surface of the Cu-Zn alloy layer (Japanese Patent Application Laid-Open No. 61-117021)
Publication). Also, an electrode wire (JP-B 2-49849) has been proposed in which an alloy layer is provided on the surface of a copper-coated steel wire so that the concentration of Zn increases toward the outer surface.

Further, Cr, Zr, Fe, Be, Co, T
An alloy containing 0.03 to 5.0% by weight of any one of i and the like is used as a core material, and a metal containing 95% or more of Zn is hot-dip plated on the surface thereof, and then cold-worked to 5% or more. (JP-A-59-134629) has also been proposed. By the way, in this proposal, among the alloys constituting the core material, a Cu—Zr alloy or a Cu—Cr alloy requires a solution treatment in order to obtain a desired tensile strength. -Solution treatment of the Cr alloy is usually performed at 950 ° C. for a wire rod of 8 to 13 mmφ.
After the heat treatment for 3 hours, rapid cooling is performed.

[0006]

Therefore, as a conventional method for manufacturing an electrode wire for electric discharge machining, a Cu--Zr alloy or a C
If the solution of the u-Cr alloy is carried out at 950 ° C. for 3 hours, it is unavoidable that this will cause an increase in cost. Down becomes possible. Further, according to the conventional electrode wire for electric discharge machining, although a certain machining speed and machining characteristics can be obtained, it is desired to further improve the machining speed and the disconnection resistance.

Accordingly, an object of the present invention is to provide a method of manufacturing an electrode wire for electric discharge machining, which enables a running solution while improving the machining speed and machining characteristics.

[0008]

In order to achieve the above-mentioned object, the present invention comprises a copper alloy containing Zr or Cr ,
A medium-sized wire rod capable of running solution is run while being heated at 700 to 950 ° C. in an inert gas atmosphere, and the wire rod that has passed through the inert gas atmosphere is immediately cooled with water.
Running solution treatment, forming a surface layer of a Zn layer or Cu-Zn layer on the surface of the wire rod after the running solution treatment,
The wire having the surface layer is cold drawn.

According to this method, a traveling solution heat treatment is performed by heating a copper alloy containing Zr or Cr while traveling in an inert gas atmosphere and cooling immediately after the heating.
The copper alloy turns into a solution. Further, a surface layer for improving the processing speed by Zn or Cu-Zn is formed on the solution-treated wire while the wire is running. As a result, in the solution treatment, the heat resistance of the electrode wire is improved, and the processing speed is improved by forming the surface layer.

The formation of the surface layer can be carried out by applying a slurry of a Zn powder, a resin anti-settling agent and a solvent, and then drying the slurry. According to this method, the material for forming the surface layer can be formed using the coating means and while the wire is running. Therefore, equipment cost can be reduced. The surface layer can be formed by an electroplating method or a hot-dip plating method. This forming method can be performed while running the wire rod, and an apparatus for this can be easily configured.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a manufacturing facility for achieving a method for manufacturing an electrode wire for electric discharge machining according to the present invention. The manufacturing equipment shown in FIG. 1 includes a traveling solution treatment line A and a powder coating line B. First, the configuration of the traveling solution heat treatment line A will be described. The traveling solution heat treatment line A has a configuration in which a payoff 1, a heating electric furnace 2, a cooling water tank 3, a constant-speed winding machine 4, and an alignment winding machine 5 are sequentially arranged in series in the processing flow direction. .

The payoff 1 has two pulleys 6a and 6b, and is used for winding and guiding a wire 7 which becomes an electrode wire for electric discharge machining after machining. The inside of the heating electric furnace 2 is heated by a heater (not shown), and openings (not shown) for inserting the wires 7 are provided at both ends. An inert (N ₂ , Ar, etc.) gas for preventing oxidation or the like from being generated on the surface of the wire 7 is supplied into the inside, and the wire 7 from the payoff 1 (this wire) is supplied in the inert gas atmosphere. 7 will be described later). The heating electric furnace 2 is provided with a gas supply port 8 and a gas discharge port 9 for flowing an inert gas.

The cooling water tank 3 is filled with a predetermined amount of cooling water 10 and a plurality of guide pulleys 11 so that the wire 7 from the heating electric furnace 2 can pass through the cooling water 10.
a, 11b, 11c, and 11d are provided. Furthermore,
The constant-speed winding machine 4 has a plurality of built-in pulleys 12a and 12b,
It has a function of sending the wire 7 from the cooling water tank 3 to the subsequent stage at a constant speed. The aligning winder 5 includes a pulley 13 that guides the wire 7 from the constant-speed winder 4 and a pulley (or reel) 14 that winds the wire 7.

Next, the configuration of the powder coating line B will be described. The wire rod 15 that has been subjected to the solution treatment in the traveling solution treatment line A is wound around a pulley 14. The wire 15 pulled out from the pulley 14 is
It is introduced into a powder coating container 16 provided with 7,18. The die 17 is provided on the entrance side of the powder coating container 16, and the die 18 is provided on the exit side. A dryer 19 is provided downstream of the powder coating container 16. The powder coating container 16 contains Zn powder (or
A slurry having a viscosity of about 1000 cps obtained by mixing three kinds of Cu--Zn powder), a resin anti-settling agent and a solvent is enclosed.

Further, a heating electric furnace 2 is provided downstream of the drying machine 19.
0 is set. The heating electric furnace 20 includes a furnace body 20a having a hollow structure inside, and a heater 20b provided around the furnace body 20a to heat the inside of the furnace body. Furnace body 20a
Inside, an inert gas (N ₂ gas) is introduced. For this purpose, a gas supply port 20c is provided at one end, and a gas exhaust port 20d is provided at the other end. This heating electric furnace 20
At the subsequent stage, a surface oxide layer removing device 21 and a bobbin 22 are sequentially installed.

In the above configuration, the wire 7 to be processed in the traveling solution heat treatment line A is, for example, 0.9 mm.
φ Cu-0.16 wt% Zr (zirconium) is used. The reason for using the Cu-Zr alloy wire is to prevent arc discharge from being generated in the electrode wire during electric discharge machining, thereby generating heat at the time of electric discharge, and preventing disconnection due to withstanding the tension during machining. It is.

The wire 7 having the above-described structure is drawn out of the payoff 1 and moves 1 m in the inert gas atmosphere of the heating electric furnace 2.
700 ° C to 95 while running at a transport speed of about
Heat to 0 ° C to form a solution. By this solution treatment,
Zr can be dissolved as a solid solution, and the electrode wire can have heat resistance. Wire 7 heated by heating electric furnace 2
Is carried into the cooling water tank 3 immediately after leaving the heating electric furnace 2,
It is rapidly cooled by the cooling water 10 in the tank. Thereafter, the cooled wire 7 is wound on the pulley 14 of the aligning winder 5 via the constant speed winder 4.

Conventionally, a Cu—Zr alloy wire is 8 to 13 mm.
A copper wire having a diameter of about φ is subjected to a solution heat treatment at 950 ° C. for 3 hours and then rapidly cooled to add heat resistance. But,
Such conventional heat treatment is costly and time consuming,
The production cost of the electrode wire for electric discharge machining cannot be reduced. Therefore, in the present invention, an intermediate size (e.g., 0.9 mmφ) capable of forming a solution at low cost is 700-950 °.
C was cooled with water after the traveling heating, so that heat resistance could be added by heat treatment in the line as described above.

Next, the processing of the powder coating line B will be described. The wire 15 (solution-treated Cu-Zr alloy wire) that has been subjected to the solution heat treatment at the traveling solution treatment line A is moved from the traveling solution treatment line A or rewound onto another bobbin or the like. ) And drawn by a die 17. Next, in the process of passing through the powder coating container 16, the surface of the wire 15 is uniformly coated with the powder. Furthermore, dryer 1
The drying of the powder coating (hot air drying) is performed in the process of passing through 9. Thereby, a surface layer containing Zn is formed on the surface of the Cu—Zr alloy wire.

Further, the wire 23 on which the surface layer is formed is sent to the heating electric furnace 20 and subjected to heat treatment. The inside of the furnace body 20a of the heating electric furnace 20 is, for example, 8
It is heated to 00 ° C., and is heated in an inert atmosphere while being conveyed in the furnace at a speed of 1 m / min. The wire 23 exiting the heating electric furnace 20 is naturally cooled in the atmosphere while moving, and thereafter, the surface oxide layer of the wire 23 is mechanically removed by the surface oxide layer removing device 21. Thereafter, the wire 23 is wound around the bobbin 22.
Furthermore, it is sent to another line and cold drawing is performed.

The wire 23 passing through the powder coating line B as described above has a surface of 10 to 10
A Cu- (30-40) wt% Zn alloy layer of about 20 μm was applied as a surface layer. Thus, Cu-Zn
By applying the alloy layer, the processing speed can be improved.

[0022]

EXAMPLES The present inventors made a prototype by the method of the present invention and evaluated the electric discharge machining property. Thickness 4 as work piece
The breaking limit speed was measured using 0 mm SKD-11. In addition, the surface roughness of the workpiece was evaluated. As a result, while using a 0.02 mm wire, the discharge current was set to 36 A, the off-time (current pause time) was kept constant (2.8 μs), and the on-time (current application time) was changed to enable processing (wire speed). (Limit speed at which the cut-off was not completed) was measured. For comparison with the present invention, 0.2 mm
A φ-35 wt% Zn electrode wire (comparative example) was prepared.

When the ON time (current application time) was 0.8 μs, the processing speed of the Cu-35 wt% Zn electrode wire (Comparative Example) was 1.53 mm / min, whereas the electrode wire according to the present invention was Was 1.75 mm / min, and it was confirmed that the processing speed was improved. In addition, when the current application time is lengthened, the processing speed increases, but the electrode wire according to the present invention has the following disadvantages.
The wire was disconnected in 2 μs. On the other hand, in the comparative example, 1.5 μs
The wire was disconnected during the current application time. From this, it was confirmed that the electrode wire according to the present invention was excellent in disconnection resistance.

Further, the surface roughness of the workpiece according to the comparative example was 1.35 μm, whereas the surface roughness of the electrode wire according to the present invention was 1.285 μm. Was found to be excellent. In forming the surface layer, in FIG. 1, it was provided by a powder coating method. However, the present invention is not limited to the powder coating method.
A hot-dip plating method or the like can be used.

Although a Cu—Zr alloy wire was used as the core material, a Cu—Cr alloy wire having the same heat resistance, Cu—Zr
An r-Cr alloy wire or the like can also be used.

[0026]

As is clear from the above, according to the present invention, a wire made of a copper alloy containing Zr or Cr is run while heating in an inert gas atmosphere, and the wire passed through the inert gas atmosphere is moved. Immediately water-cooled and solution treated,
A surface layer of a Zn layer or a Cu-Zn layer is formed on the surface of this wire, and furthermore, a method of manufacturing an electrode wire for electric discharge machining by cold drawing is adopted. Improvement and cost reduction can be achieved, and the processing speed can be improved by forming the surface layer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a manufacturing facility for achieving a method for manufacturing an electrode wire for electric discharge machining according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Payoff 2 Heating electric furnace 3 Cooling water tank 4 Alignment winding machine 7 Wire rod 10 Cooling water 16 Powder coating container 17, 18 Dice 19 Dryer 20 Heating electric furnace 21 Surface oxide layer removal apparatus

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-134624 (JP, A) JP-A-4-176849 (JP, A) JP-A-62-4834 (JP, A) JP-A-5-134 177443 (JP, A) JP-A-61-136733 (JP, A) JP-A-59-153805 (JP, A) JP-A-3-68734 (JP, A) JP-A-61-197126 (JP, A) JP-A-6-79535 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23H 7/08

Claims (3)

(57) [Claims] 1. A traveling device made of a copper alloy containing Zr or Cr.
A medium-sized wire rod capable of solution treatment is run while being heated at 700 to 950 ° C. in an inert gas atmosphere, and the wire rod that has passed through the inert gas atmosphere is immediately cooled with water and run. An electrode for electric discharge machining, wherein a surface layer of a Zn layer or a Cu-Zn layer is formed on the surface of the wire rod which has been subjected to the running solution treatment, and the wire rod having the surface layer is cold drawn. Wire manufacturing method. 2. The electrode wire for electric discharge machining according to claim 1, wherein said surface layer is formed by applying a slurry of a Zn powder, a resin settling inhibitor and a solvent in a slurry state and then drying the slurry. Production method. 3. The method according to claim 1, wherein the surface layer is formed by an electroplating method or a hot-dip plating method.