JPH1015739A - Manufacture of wire electric discharge machining electrode wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a wire electric discharge machining electrode wire having a high heating speed or a short heating time, eliminating necessity for a heating furnace and reduction gas, also with no time and skill required for position adjusting of a finish die, to be excellent in tensile strength and high temperature tensile strength, eliminating twist and improving straightness. SOLUTION: In a method of manufacturing a brass electrode wire or compound electrode wire W in a very fine region size of 0.01 to 0.10mmϕ wire size, the applied annealing voltage and applied annealing current are adjusted, in the case of performing running current carrying heating for obtaining tensile strength and straightness of the brass electrode wire or the compound electrode wire W, so that input energy represented by 0.24×E×I×(1/3<1/2> ) (E: applied annealing voltage, I: applied annealing current (= preheat current + heating current) is 15.0 to 17.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrode wire for wire electric discharge machining, and more particularly to a method for drawing and annealing an extremely fine electrode wire for wire electric discharge machining.

[0002]

2. Description of the Related Art In the wire electric discharge machining, an arc discharge is generated between a workpiece and a wire, and the workpiece is processed into a predetermined predetermined shape while melting the workpiece.

[0003] As a general electrode wire for wire electric discharge machining at present, brass (Cu) having a wire diameter of 0.1 to 0.3 mmφ is used.
-Zn) wire, alloy brass wire (JP-B-59-9298), or a composite wire in which brass is coated with zinc (Zn) or brass (JP-B-57-5648). In addition, as a fine processing electrode wire such as a lead frame mold, a tungsten-molybdenum (W.Mo) wire having high strength or a composite wire obtained by coating a steel wire with brass (Japanese Patent Laid-Open No. 62-259719). Gazettes), etc., and any of the electrode wires for wire electric discharge machining is usually produced by wire drawing.

[0004] In addition to tensile strength and electric discharge machining, straightness is an important characteristic of the wire for wire electric discharge machining. The straightness of the wire affects the automatic wire connection, and not only facilitates the wire through the die guide of the wire EDM at the start of wire EDM, but also the wire EDM such as unmanned operation at night It is also important to increase the operating rate of

[0005] That is, in the wire electric discharge machining, when moving from machining of one workpiece to machining of the next workpiece, an electrode wire for wire electric discharge machining of a used portion is cut off.
Since the next workpiece is moved to the machining start position and a new electrode wire for wire electric discharge machining is sent out and automatic connection is performed, automatic connection is performed if the straightness of the electrode wire for wire electric discharge machining is poor. And the wire electric discharge machining cannot be performed continuously.

The following methods have been proposed as conventional methods for improving the tensile strength and straightness of an electrode wire for wire electric discharge machining.

(A) A method in which current is heated in a reducing gas or the like. (B) A method in which tension is applied to an electrode wire for wire electric discharge machining while heating using a continuous heating furnace (Japanese Patent Laid-Open No. 17744/1993).
(Claim 3) (c) A method of adjusting the position of a finishing die so that the straightness of the electrode wire for wire electric discharge machining becomes the best during wire drawing of the electrode wire for wire electric discharge machining (Japanese Unexamined Patent Publication No. 3-35809).
No.)

[0008]

However, the tungsten-molybdenum wire used for micromachining is hard, so that the cutting of the cutter during automatic connection is not successful, and the consumption of the cutter is faster than that of brass wire or the like. There is a problem. Further, in the case of a composite wire, the residual stress in the cross section of the wire tends to be non-uniform, and the straightness of the electrode wire for wire electric discharge machining obtained after the die drawing is uneven.

[0009] The conventional method of imparting straightness has the following problems.

For example, in the case of a method using external heating such as a tubular furnace, the heating rate (time) is extremely low, and the working efficiency is very poor.

In the case of the method of heating in a reducing gas (H ₂ , N _2, etc.) atmosphere, it is difficult to control the reducing gas,
In addition, there is a danger, and it is difficult to put it to practical use as a method for imparting straightness particularly to an extra-fine electrode wire for wire electric discharge machining.

In the case of a method of improving straightness by adjusting the finishing die position of a wire drawing machine, although there are great economical and working efficiency advantages as compared with the method described above, the wire is adjusted by adjusting the position of the finishing die. In order to achieve the straightness of the electrode wire for electric discharge machining, the know-how and skill of an operator are required. In addition, every time the size of the electrode wire for wire electric discharge machining is changed, the position of the finishing die must be adjusted, and a position where the line cross section and the residual stress distribution are point-symmetrical must be searched. Even if a point-symmetric position can be found, it is difficult to obtain good straightness unless residual stress remaining on the entire electrode wire for wire electric discharge machining is removed.

Therefore, the present invention solves the above-mentioned problems, and does not require a heating furnace or a reducing gas, and requires time and time for adjusting the position of the finishing die.
An object of the present invention is to provide a method for manufacturing an electrode wire for wire electric discharge machining, which does not require skill, has excellent tensile strength and high-temperature tensile strength, has no twist, and has good straightness.

[0014]

In order to solve the above-mentioned problems, the invention according to claim 1 has a wire diameter of 0.01 to 0.10 mmφ.
In the method for producing a brass electrode wire or a composite electrode wire having the ultrafine region size described above, when conducting running heating for obtaining the tensile strength and straightness of the brass electrode wire or the composite electrode wire, the input energy: 0.24 × ^{E × I × (1/3 1/2)} (E: applied annealing voltage, I: applying annealing current (= preheating current +
The input energy represented by (heating current)) is 15.0 to
The applied annealing voltage and the applied annealing current are adjusted so as to be 17.0.

The invention according to a second aspect of the present invention provides a method for changing the applied annealing voltage E ₂ when only the wire speed is changed while the wire diameter of the brass electrode wire or the composite electrode wire is the same during the running heating.
And E ₂ = (v ′ / v) ^1/2 × E ₁ (v ′: linear velocity after change, v: linear velocity before change, E ₁ : applied annealing voltage before change). It is a manufacturing method of the electrode wire for wire electric discharge machining described.

The reason for limiting the above numerical range will be described below.

The range of input energy is 15.0-17.
The reason for limiting to 0 is that when the input energy is less than 15.0, the tensile strength is excellent, but the input energy is too small, the removal of the residual stress of the electrode wire for wire electric discharge machining becomes incomplete, and the torsion easily occurs. If the input energy is larger than 17.0, over-annealing occurs and twisting does not occur, but the tensile strength is greatly reduced, and the variation in straightness (width) is large.

According to the above construction, the wire diameter is 0.01 to
In the method for producing a brass electrode wire or a composite electrode wire having an ultra-fine area size of 0.10 mmφ, when performing energizing heating for traveling to obtain the tensile strength and straightness of the brass electrode wire or the composite electrode wire, the input energy: 0 .24 × E × I × (1/3 1/2) (E: applied annealing voltage, I: applying annealing current (= preheating current +
The input energy represented by (heating current)) is 15.0 to
Since the applied annealing voltage and the applied annealing current were adjusted to 17.0, the heating rate or the heating time was high, so that a heating furnace and a reducing gas were not required, and it took time and skill to adjust the position of the finishing die. In addition, it is possible to obtain an electrode wire for wire electric discharge machining that is excellent in tensile strength and high-temperature tensile strength, free from twisting, and has good straightness.

[0019]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic view of an apparatus for manufacturing an electrode wire for wire electric discharge machining according to the present invention.

As shown in FIG. 1, an apparatus 1 for manufacturing an electrode wire for wire electric discharge machining according to the present invention comprises a continuous wire drawing machine 3, an electric heating device (annealer) 5, and a winding device 9.

The continuous wire drawing machine 3 uses a bobbin-shaped shaft (not shown) to move an electrode wire W for wire electric discharge machining (hereinafter referred to as a wire).
W supplied from a wire base material 2 wound around
Are provided with a plurality of drawing dies 4 (two in the figure), and pulleys 11 are provided before and after each drawing die 4, respectively.

The electric heating unit 5 includes an electric heating unit 5a for performing annealing for removing strain energy of the wire W supplied from the continuous wire drawing machine 3 and a cooling unit 5b for cooling the wire W after annealing. It consists of. The energization heating section 5 a includes a preheating zone 6 and a heating zone 7.

The winding device 9 is provided with a bobbin 10 for winding the wire W fed from the electric heating device 5.

Next, a method of manufacturing the electrode wire for wire electric discharge machining according to the present invention will be described.

The method for manufacturing an electrode wire for wire electric discharge machining according to the present invention is roughly divided into three parts: a wire drawing step, an electric heating step, and a winding step.

The wire W supplied from the wire preform 2 is fed to a continuous wire drawing machine 3 which is a wire drawing process, and is passed through a wire drawing die 4a for wire drawing. The wire W passed through the wire drawing die 4a is pulled by a pulley 11 located behind the wire drawing die 4a.
b, and the wire drawing die 4a is inserted again through the pulley 11a located in front of the wire drawing die 4a to perform finishing. Thereafter, the wire W is drawn into a wire drawing die 4b having a smaller diameter than the wire drawing die 4a.
And wire drawing. The wire W inserted through the wire drawing die 4b is pulled into the pulley 1 located behind the wire drawing die 4b.
In addition to running backward through 1d, the wire drawing die 4b is inserted again through the pulley 11c located in front of the wire drawing die 4b to perform finishing processing to a predetermined wire diameter.

The wire W that has been subjected to the wire drawing is fed to an electric heating device 5 which is an electric heating step,
Through the heating section 5a and the cooling section 5b.

The preheating current flows by applying a preheating voltage to the wire W at the preheating voltage application point P _1, to preheat the wire W by the preheating current. Then, at the point P ₂ of the applied annealing voltage, the applied annealing voltage E
Is applied. Here, between the preheating voltage applying point P ₁ ~ applied annealing voltage applying point P ₂ is preheating zone 6.

By applying the applied annealing voltage E,
_On the downstream side of the applied annealing voltage application point P _{2 on} the wire W, the pre-heating current and the heating current are combined to apply the applied annealing current I
Flows. Feeding the wire W which is energized to apply annealing current I to the cooling unit 5b feeds, while immersed in annealer coolant C, and discharged at ground point P _3. Here, the heating zone 7 is between the point P _{2 of} applying the applied annealing voltage and the point P ₃ between the ground point.

At this time, the preheating zone 6,
Among the energization heat treatment conditions in the heating zone 7, the input energy is: input energy: 0.24 × E × I × (1/3 ^1/2 ) =
15.0 to 17.0: By adjusting the applied annealing voltage E and the applied annealing current I so that the (1/3 ^1/2 energy loss factor), without torsion, straightness (curl index, width, Thus, it is possible to obtain an electrode wire for wire electric discharge machining, which has good peaks and excellent tensile strength (including high-temperature strength) as a hard material. Here, the energy loss coefficient is a value obtained by applying a ratio of energy loss (irrational number) caused by applying energy (current and voltage) in the anneal cooling water C.

Thereafter, the wire W is fed to the winding device 9 and wound on the bobbin 10 to obtain the electrode wire for wire electric discharge machining of the present invention.

When only the linear velocity is changed while keeping the wire diameter of the wire W the same, the applied annealing voltage E ₂ after the change is: E ₂ = (v ′ / v) ^1/2 × E ₁ (v ′) : Linear velocity after the change, v: linear velocity before the change, E ₁ : applied annealing voltage before the change).

If the linear velocity ratio (= the linear velocity after the modification / the linear velocity before the modification) is simply multiplied by the applied annealing voltage E ₁ before the modification as it is, the wire W will be over-annealed. This greatly reduces the variation in straightness as well.
Therefore, in order also to ensure after the linear velocity change (removal of strain energy) obtained have a straightness in ohmic heating treatment conditions before the change, the linear velocity ratio to the applied annealing voltage E ₁ before the change (=
The linear velocity after the change / the linear velocity before the change) is raised to the power of 1/2. As a result, it is possible to obtain an electrode wire for wire electric discharge machining which is free from twisting even after the change in the linear velocity, has good straightness, and has excellent tensile strength (including high-temperature strength).

[0035]

【Example】

(Example 1) A billet having a diameter of 115 mm and a length of 900 mm is formed into a base material having a diameter of 6.5 mm by hot extrusion. By repeating wire drawing and annealing on this base material, an intermediate material having a diameter of 0.175 mmφ is produced. A linear velocity of 200 m / min, an applied annealing current of 3.9 A (a preheating current of 1.9 A, a heating current of 2.0
A), the applied annealing voltage is 30.0 V, and the input energy is 1
Electric heating for running under the condition of 6.21 is performed, and the diameter is 0.0
An electrode wire for wire electric discharge machining having a diameter of 7 mm was produced.

Example 2 The same intermediate material as in Example 1 was used.
Running energization heating is performed under the conditions that the linear velocity is 200 m / min, the applied annealing current is 3.6 A (preheating current 1.8 A, heating current 1.8 A), the applied annealing voltage is 30.3 V, and the input energy is 15.11. And an electrode wire for wire electric discharge machining having a diameter of 0.07 mmφ.

Example 3 The same intermediate material as in Example 1 was used.
Running energization heating is performed under the conditions that the linear velocity is 200 m / min, the applied annealing current is 3.7 A (preheating current 1.8 A, heating current 1.9 A), the applied annealing voltage is 30.5 V, and the input energy is 15.64. And an electrode wire for wire electric discharge machining having a diameter of 0.07 mmφ.

Comparative Example 1 The same intermediate material as in Example 1
Running energization heating is performed under the conditions that the linear velocity is 200 m / min, the applied annealing current is 3.3 A (preheating current 1.6 A, heating current 1.7 A), the applied annealing voltage is 24.0 V, and the input energy is 10.97. And an electrode wire for wire electric discharge machining having a diameter of 0.07 mmφ.

(Comparative Example 2) The same intermediate material as in Example 1
Only wire drawing at a linear speed of 200 m / min was performed to produce an electrode wire for wire electric discharge machining having a diameter of 0.07 mmφ.

Comparative Example 3 The same intermediate material as in Example 1 was used.
Running energization heating is performed under the conditions that the linear velocity is 200 m / min, the applied annealing current is 4.3 A (preheating current 2.1 A, heating current 2.2 A), the applied annealing voltage is 40.0 V, and the input energy is 23.83. And an electrode wire for wire electric discharge machining having a diameter of 0.07 mmφ.

(Comparative Example 4) The same intermediate material as in Example 1
Running energization heating is performed under the conditions that the linear velocity is 200 m / min, the applied annealing current is 5.1 A (preheating current 2.5 A, heating current 2.6 A), the applied annealing voltage is 48.5 V, and the input energy is 34.27. And an electrode wire for wire electric discharge machining having a diameter of 0.07 mmφ.

Table 1 shows the specifications and evaluation results of the electrode wires for wire electric discharge machining in Examples 1 to 3 and Comparative Examples 1 to 4.

[0043]

[Table 1]

Here, the evaluation of the electrode wire for wire electric discharge machining was performed with respect to tensile strength (MPa), straightness (curl rate (%), curl width (mm), curl peak (piece)), and presence or absence of twist. Was. The curl ratio is the ratio of the curl portion to the entire length of the electrode wire for wire electric discharge machining, the curl width is the curved width of the electrode wire for wire electric discharge machining, and the curl peak is the number of peaks in the entire length of the electrode wire for wire electric discharge machining. It is.

As shown in Table 1, each of the electrode wires for wire electric discharge machining of Examples 1 to 3 had the input energy of 16.
21, 15.11, 15.64 and the specified range (15.0 to
17.0), the tensile strength is as good as 1,700 MPa or more, and the straightness is about 0.2% or less, the width is about 15 mm or less, and the peak is One was good. Furthermore, no twisting was observed.

On the other hand, in the case of the electrode wires for wire electric discharge machining of Comparative Examples 1 and 2, the tensile strengths were as good as 1,872 MPa and 1,978 MPa, respectively.
Since the input energies are 10.97 and 0, respectively, smaller than the specified ranges, the residual stress of the electrode wire for wire electric discharge machining is incompletely removed, and twisting is observed.

In the case of the electrode wires for wire electric discharge machining of Comparative Examples 3 and 4, although no twisting was observed,
Since the input energies are 23.83 and 34.27, respectively, which are larger than the specified ranges, over-annealing occurs, the tensile strength is greatly reduced, and the variation in straightness is also large.

FIG. 2 shows the relationship between the input energy and the tensile strength and the relationship between the input energy and the straightness / width. The curve (a) shows the tensile strength, and the curve (b) shows the straightness / width.

As shown by the curve (a) in FIG. 2, the tensile strength reaches its maximum value (about 1,8 when the input energy is about 10).
70 MPa), and thereafter decreases with an increase in the input energy. In contrast, the curve (b) in FIG.
As shown in the figure, the straightness and width are minimal when the input energy is about 15 and about 17 (about 5 mm and about 10 m, respectively).
m). The tensile strength at this time was about 1,72, respectively.
0 MPa, about 1,740 MPa. When the input energy is in the range of 15 to 17, the maximum value is exhibited when the input energy is about 16, the straightness / width is about 14 mm, and the tensile strength is about 1,750 MPa. The input energy is slightly out of the range of about 15 to 17 (<15 or 1
7 <), the straightness / width sharply deteriorates (increases).

In the electrode wire for wire electric discharge machining, straightness (that is, automatic connection) is regarded as important, not to mention tensile strength and electric discharge machinability. For this reason, it is most desirable that the input energy to be applied at the time of energizing and heating the electrode wire for wire electric discharge machining be in the range of 15.0 to 17.0. Further, it is needless to say that the tensile strength of the electrode wire for wire electric discharge machining in this range is 1,700 MPa or more, and has a sufficient strength.

[0051]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) Excellent tensile strength and high temperature tensile strength,
It is possible to obtain an electrode wire for wire electric discharge machining which has no twist and has good straightness.

(2) Since the heating of the electrode wire for wire electric discharge machining is not a method based on external heating such as a tubular furnace, the heating rate or the heating time is high.

(3) Since the heating of the electrode wire for wire electric discharge machining is not performed in a reducing gas atmosphere, it is difficult to control the reducing gas and there is no danger.

(4) In the method of manufacturing an electrode wire for wire electric discharge machining according to the present invention, although a wire drawing die is used for improving straightness, the residual stress remaining on the entire electrode wire for wire electric discharge machining is removed by energization. Since heating is performed, time and skill are not required for adjusting the position of the finishing die.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing an electrode wire for wire electric discharge machining according to the present invention.

FIG. 2 is a diagram showing a relationship between input energy, tensile strength, and straightness.

[Description of Signs] 1 Manufacturing apparatus 2 Wire preform 3 Continuous wire drawing machine 5 Electric heating device 5a Electric heating unit 5b Cooling unit 6 Preheating zone 7 Heating zone 9 Winding device W Electrode wire for wire electric discharge machining (brass electrode wire or Composite electrode wire) C Annealer cooling water P ₁ Preheating voltage application point P ₂ Applied annealing voltage application point P ₃ Earth point

Claims (2)

[Claims] 1. A method for producing a brass electrode wire or a composite electrode wire having a wire diameter of 0.01 to 0.10 mmφ in an ultrafine region size, wherein the brass electrode wire or the composite electrode wire has a tensile strength and a straightness. when performing driving electric heating, input energy: 0.24 × E × I × ( 1/3 1/2) (E: applied annealing voltage, I: applying annealing current (= preheating current +
The input energy represented by (heating current)) is 15.0 to
A method for producing an electrode wire for wire electric discharge machining, wherein an applied annealing voltage and an applied annealing current are adjusted so as to be 17.0. 2. In the case where only the wire speed is changed while the wire diameter of the brass electrode wire or the composite electrode wire is the same at the time of running electric heating, the applied annealing voltage E ₂ after the change is expressed as E ₂ = (v ′). / V) ^1/2 × E ₁ (v ′: linear velocity after change, v: linear velocity before change, E ₁ : applied annealing voltage before change). Manufacturing method.