JPH10128623A - Manufacture of electrode wire for electric discharge machining and device therefof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and stably obtain excellent straightness of a wire. SOLUTION: A wire 16, after it is suitably elongated through a plurality of dies by traction with a capstan, is finished to a prescribed wire size by finish dies 14. Just before the wire 16 via the capstan is placed in the finish dies 14, on the coaxial line of an axial hole 17 thereof, the wire 16 is positioned, to be straightly put into the axial hole 17. Between the capstan and the finish dies 14, guide dies 15 are provided, the wire is positioned in a prescribed distance L approximate from the finish dies 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an electrode wire for electric discharge machining by drawing a capstan.

[0002]

2. Description of the Related Art In electric discharge machining, an arc discharge is generated between a workpiece and a wire, and the workpiece is melted and processed into a predetermined arbitrary shape programmed.
The wire is generally a brass wire having a wire diameter of 0.1 to 0.3 mm, an alloy brass wire (for example, Japanese Patent Publication No. 59-9298), or zinc (Zn) or brass (Cu / Cu).
Composite wire coated with Zn) (for example, Japanese Patent Publication No. 57-564).
No. 8) is used. In addition, as an electrode wire for fine processing such as a mold used for manufacturing a lead frame, a tungsten-molybdenum wire having high strength or a composite electrode wire obtained by coating a copper wire with brass (for example, Japanese Patent Publication No. 62-259719). ), And any wire is usually manufactured by wire drawing. In the wire drawing, for example, a wire is wound around a pair of capstans and pulled, whereby the wire is appropriately drawn through a plurality of dies, and processed to a predetermined wire diameter by a finishing die.

On the other hand, as properties required for a wire, tensile strength and discharge properties are naturally important, but straightness free of wire distortion is required. This requires automatic wire connection in a wire electric discharge machine in order to increase the operation rate, such as rationalization of work and unmanned continuous operation at night, and straightness of the wire is necessary for this. With this automatic connection, when moving from one electric discharge machining to the next electric discharge machining, cutting the wire by a cutter or energizing cutting method, moving the workpiece on the table to the next electric discharge machining start position, The next electrical discharge machining is started by automatically inserting and connecting the wire into the die guide and the like. Therefore, if the straightness of the wire is poor, it is difficult to insert the wire into the die guide, the start hole, and the like, and in some cases, the machine may be stopped.

Conventionally, as a technique for improving the straightness of a wire, a method of removing the residual stress by heating the wire and applying a tension to obtain the straightness (Japanese Unexamined Patent Publication No.
245919), a method of adjusting the position of a finishing die so that the straightness of the wire becomes the best (Japanese Patent Laid-Open No.
JP-A-35809) has been proposed.

[0005]

However, the conventional wire manufacturing method has the following problems. First, the method of heating a wire has a problem that equipment costs are increased because a tubular furnace or the like is required for heating, and the number of man-hours increases, leading to a reduction in efficiency. In the method of adjusting the finishing die position, there are few economical and working efficiency disadvantages such as the heating method, but it requires a high degree of skill to search for a point where the residual stress distribution of the line cross section is point symmetric. Therefore, the straightness of the wire varies depending on the operator. There is also a problem that every time the wire size is changed, the troublesome position adjustment of the finishing die must be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and provides a method and apparatus for manufacturing an electrode wire for electric discharge machining capable of easily and stably obtaining excellent straightness with a simple structure. It was invented to do so.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an electrode for electric discharge machining in which a wire is appropriately drawn through a plurality of dies by pulling by a capstan and then finished to a predetermined wire diameter with a finishing die. In the method of manufacturing a wire, the wire passing through the capstan is positioned on the same axis as the shaft hole immediately before entering the finishing die, and is inserted straight into the shaft hole. Further, the present invention is an apparatus for carrying out this manufacturing method, wherein a capstan for pulling a wire through a plurality of dies as needed is drawn, and the wire passing through the capstan is finished to a predetermined wire diameter. In a manufacturing apparatus of an electric discharge machining electrode wire having a wire drawing die, a guide die is provided between a capstan and a wire drawing die, and the guide die is inserted straight into a shaft hole of the wire drawing die. As described above, it is located at a predetermined distance close to the wire drawing die. In this manufacturing apparatus, the distance between the guide die and the wire drawing die is L, the wire diameter is D, the wire drawing speed is Vs, the wire drawing lubricating oil concentration is Jr, the mechanical reduction is Mr, and the wire reduction is Wr. L ≦ (D / 2) ² π × Vs × J
It is preferable to satisfy r / (Mr-Wr). The drawing die is a finishing die for finally finishing the wire. Alternatively, it may be a finishing die and a ground-winding die that works until finishing.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, the reason why straightness is poor when manufacturing an electrode wire for electric discharge machining will be considered. FIG.
(A) shows an example of a continuous wire drawing machine that performs wire drawing, and passes through a pair of capstans 1A and 1B for wrapping around the wire 3 and drawing appropriately, and the capstans 1A and 1B. And a finishing die 4 for finishing the wire 3 to a predetermined wire diameter. A final capstan 2 is provided behind the finishing die 4. In such a configuration, a slip occurs between the wire drawing capstans 1A and 1B and the wire 3. This is because the wire 3 is pulled out from the finishing die 4 by the rotation (speed) of the final capstan 2.
The peripheral speed of B is faster and slips. Due to this slip, the wire 3 follows a wavy trajectory 5 that deviates from the ideal linear trajectory 7 and has a node at the position of the rear capstan 1B, and has an irregular arc with respect to the finishing die 4. Enter in a state (deflection). That is, FIG.
As shown in FIG.
As a result, the residual stress of the manufactured wire 3 becomes not only uneven in the circumferential direction, but also causes uneven wear of the finishing die 4, resulting in variation in straightness. , Good straightness cannot be obtained. Therefore, even if the guide die 6 is simply provided in front of the finishing die 4 as shown in the drawing, an arc trajectory having this die position as a node remains, and there is no effect on the improvement of straightness.

FIGS. 1 and 2 show an embodiment of the present invention devised in view of such circumstances. In the production apparatus 11 for an electric discharge machining electrode wire, a coaxial guide die 15 is provided between a pair of capstans 12 and 13 and a finishing die 14, and a guide die 1 is provided.
5 is arranged at a predetermined distance L close to the finishing die 14 so that the wire 16 enters the shaft hole 17 of the finishing die 14 straight. Capstan 12,
Numeral 13 is a frustoconical roller having a predetermined taper, and as shown in FIG. 2, they are juxtaposed so that their rotation axes are parallel and slightly offset from each other in the axial direction. A wire 1 is inserted between these capstans 12 and 13.
6 is multiplied, so that appropriate wire drawing is performed according to the difference in the peripheral speed. Between the pair of capstans 12 and 13, a plurality of ground-winding dies 18 that perform operations up to finishing are provided. Finishing dies 15
Together with the ground winding die 18, it is called a wire drawing die. The guide die 15 has a rectangular cross section in outer shape, a shaft hole 19 corresponding to the wire diameter formed in the center, and both ends thereof are slightly enlarged in diameter. The guide die 15 may be a skin pass die that does not have a reduction rate of the cross section, or may be a roller-shaped one in the circumferential direction of the wire. The finishing die 14 has a rectangular cross-sectional shape similar to that of the guide die 15, and has a shaft hole 17 formed in the center. The shaft hole 17 is formed in a tapered shape, and is smaller than the inlet side so that the diameter on the outlet side becomes a diameter corresponding to the finished diameter (wire diameter D).

The wire 16 generated by the slip
Varies with the capstan peripheral speed, wire drawing speed, wire drawing lubricant concentration (friction coefficient), size, and the like. That is, if the distance between the guide die 15 and the finishing die 14 is extremely long, the wire 16 coming out of the guide die 15 will run out, and it will be difficult to obtain good straightness. In view of this, in the present invention, the distance L between the guide die 15 and the finishing die 14 satisfies the following expression.

L ≦ (D / 2) ² π × Vs × Jn / (Mr−Wr) L: distance between dies (mm) D: wire diameter (mm) Vs: drawing speed (m / min) Jn: Drawing wire lubricating oil concentration (%) Mr: mechanical reduction (%) Wr: wire reduction (%) Here, the distance L between the dies is a distance from the outlet side surface 20 of the guide die 15 to the inlet side surface 21 of the finishing die 14, The wire diameter D is the product wire diameter after passing through the finishing die 14,
The drawing speed Vs is equal to the peripheral speed of the final capstan 22.
This is the speed after passing through the finishing die 14. The wire drawing lubricating oil concentration Jn is selected to be suitable for the wire diameter D.
It is related to the coefficient of friction. This wire drawing lubricating oil concentration J
If n is too low, "line chatter" during die wear, wire drawing, etc.
Will occur. Conversely, if the concentration is high, "line breakage" or the like may occur, and the wire 16 may protrude from the capstans 12, 13, 22 in some cases. Further machine reduction M
r is a deceleration rate from one capstan to the next capstan, and wire reduction Wr is a cross-section reduction rate of the wire 16. By setting the distance L between the dies as described above, the wire 16 via the capstans 12 and 13 can be used.
Is positioned on the same axis as the shaft hole 17 by the guide die 15 immediately before entering the finishing die 14, and enters the shaft hole 17 straight regardless of the presence or absence of slip.

Table 1 shows the results of determining the straightness of the wires (Examples 1, 2, and 3) manufactured by the manufacturing apparatus 11 having this configuration. In the same table, the wires (Comparative Examples 4, 5, and 6) manufactured by the wire drawing machine having the guide die 15 but not having the installation requirements of the present invention, and the wire manufactured by the wire drawing machine without the guide die 15 are used. The wire (conventional example 7) is also shown. The manufacturing conditions are as follows: a hard electrode wire having a wire diameter D of 0.07 mm, a drawing speed Vs of 200 m / min, a drawing lubricating oil concentration Jn of 11%, a mechanical reduction Mr of 8%, and a wire reduction Wr of
It was 5.48%. Therefore, according to the formula, the guide die 15
Should be set within a distance of 3.36 mm from the finishing die 14. Note that “curl rate”, “width”, and “mountain” were used as the straightness determination values. These values are obtained as follows. Take a test piece about 1,500 mm long from the bobbin of the product, mark it at a position 1,000 mm from one end, and hang it vertically as shown in Fig. 3. Next, the dimension from the marked line 31 to one end of the test piece 32 is measured without applying tension, and this value is set to λ (mm), and the curl rate C (%) is calculated by the following equation. Further, a convex portion formed in the left-right direction between λ is regarded as a “mountain” (symbol Y), the number y is counted (two in the illustrated example), and the distance (height) W between the peaks of the “mountain” Is measured to obtain the value of “width”.

C = {(1,000−λ) / 1,000} × 100

[0015]

[Table 1]

As shown in Table 1, in the first and second embodiments, the distance satisfying the above equation (L = 3.23 mm, 2.46 mm)
In each case, the “width” indicating straightness is good as W = 10 mm and W = 15 mm, and the curl rate C is
0.1%, the number y of "mountains" was also one, and no generation of twisting was observed. In Example 3, the finishing dies 1
4 and the guide die 15 are installed in front of the ground winding die 18, and the distance between the dies (L = 3.
23 mm), no twist, and the straightness was further improved (W = 5 mm). On the other hand, in Comparative Examples 4 and 6 in which the guide dies 15 are installed at distances (L = 20.76 mm, 25.48 mm) that do not satisfy the above expression, the values indicating the straightness vary (C = 0.2 to 0.3%, W = 60 ~
85mm, 55 to 75mm, y = 1 to 2), W = 20mm or less, which is a standard for good automatic connection, could not be cleared. In Comparative Example 4, twisting was also observed. In Comparative Example 5, the guide dies 15 were provided only in front of the ground winding dies 18. Even when the distance L between the dies satisfied the above expression (L = 3.23 mm), the straightness was low. (C = 0.3-0.4%, W = 80-90mm, y = 2-3)
), Twisting was also observed. Guide dice 1
In the conventional example 7 having no example 5, the straightness was reduced to the examples 1 to 3 of the present invention.
(C = 0.4-0.5%, W = 60)
~ 95mm, y = 2 ~ 3). Therefore, it has been proved that the manufacturing method of the present invention is extremely effective for improving the straightness of the wire 16.

Focusing on the fact that the straightness of the wire 16 is reduced due to the arc-shaped wire locus due to slippage in the manufacturing process (see FIG. 4 described above), the wire locus can be corrected. Since the guide die 15 is provided between the finishing die 14 and the capstans 12 and 13, and the guide die 15 is located at a distance (L) close to the finishing die 14, there is no line distortion such as curl or twist. An excellent straightness wire 16 can be obtained easily and without variation. That is, the automatic connection property of the wire 16 can be improved, and the efficiency of the continuous electric discharge machining operation by the electric discharge machine equipped with the automatic connection mechanism can be improved. In addition, the present invention has a simple configuration in which the guide die 15 is installed at a distance L between the dies that satisfies the expression. Therefore, even if the manufacturing conditions such as a change in the size of the wire 16 are changed, the calculation of the expression and the calculated value It is only necessary to set the guide die 15 based on the above, no skill is required, and anyone can set it easily and quickly. By providing the guide die 15 not only in the finishing die 14 but also immediately before the ground winding die 18, the straightness can be further improved. This guide die 15
As an effect, in addition to the prevention of line runout, suppression of pulling force of a finishing die or the like can be obtained as a synergistic effect.

In the method of manufacturing an electrode wire for electric discharge machining according to the present invention, the guide die 1 shown in the above embodiment is used.
5 in place of a wire drawing die (1
By performing center alignment on (4, 18), it is also possible to obtain a good straightness by inserting the wire 16 straight. The present invention also includes alloy brass wire including brass wire,
It can also be applied to composite electrode wires coated with zinc or brass.

[0019]

In summary, according to the present invention, excellent straightness can be obtained easily and without variation, and an excellent effect of improving automatic wire connection can be exhibited.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part showing an embodiment of a method and an apparatus for manufacturing an electrode wire for electric discharge machining according to the present invention.

FIG. 2 is a plan view showing the whole of FIG. 1;

FIG. 3 is a side view showing a method of evaluating straightness of a wire for explaining the operation and effect of FIG. 1;

FIG. 4 is a diagram for explaining a basic technique of the present invention;
(A) is a side view, (b) is a principal part enlarged view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Manufacturing apparatus of electrode wire for electric discharge machining 12, 13 Capstan 14 Finishing dies (drawing dies) 15 Guide dies 16 Wire 17 Shaft hole 18 Ground winding dies (drawing dies) D Wire diameter L Distance between dies (approx. distance)

Claims (5)

[Claims] 1. A method for producing an electrode wire for electric discharge machining, in which a wire is appropriately drawn through a plurality of dies by pulling with a capstan and then finished to a predetermined wire diameter with a finishing die, the wire passing through the capstan is removed. A method for manufacturing an electrode wire for electric discharge machining, wherein the electrode wire is positioned on the same axis as the shaft hole immediately before being put into the finishing die, and is inserted straight into the shaft hole. 2. An electric discharge machining method comprising: a capstan for pulling a wire through a plurality of dies to draw the wire appropriately; and a wire drawing die for finishing the wire passing through the capstan to a predetermined wire diameter. In the apparatus for manufacturing an electrode wire, a guide die is provided between the capstan and the wire drawing die, and the guide die is inserted into the wire drawing die so that the wire goes straight into an axial hole of the wire drawing die. A manufacturing apparatus for an electrode wire for electric discharge machining, wherein the apparatus is located at a predetermined distance close to the electric wire. 3. The apparatus for manufacturing an electrode wire for electric discharge machining according to claim 2, wherein the distance between the guide die and the wire drawing die is L, the wire diameter is D, the wire drawing speed is Vs, and the wire drawing is performed. When the lubricating oil concentration is Jr, the mechanical reduction is Mr, and the wire reduction is Wr, the following condition is satisfied: L ≦ (D / 2) ² π × Vs × Jr / (Mr−Wr) Equipment for manufacturing electrode wires. 4. The apparatus for producing an electrode wire for electric discharge machining according to claim 2, wherein the drawing die is a finishing die for finally finishing the wire. 5. The apparatus for producing an electrode wire for electric discharge machining according to claim 2, wherein the wire drawing die is a finishing die for finally finishing the wire and a ground winding die acting until finishing. .