JPS5917544Y2 - Wire cut electrical discharge machining equipment - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a wire-cut electrical discharge machining apparatus that relatively moves a wire electrode and a workpiece and processes the workpiece into a desired contour and shape using the wire electrode.

A conventionally known wire-cut electrical discharge machining apparatus of this type will be explained with reference to FIG.

Figure a is a configuration diagram, and figure b is a sectional view of a main part.

A wire electrode 1 with a diameter of 05 to 0.3 mm is usually supported at two locations: an upper wire guide 2 and a lower wire guide 3.
In the machining section 4, a pulse current is supplied by the machining power source 8 through the machining fluid 7 supplied from the machining fluid nozzle 6 in the machining gap where the wire electrode 1 and the workpiece *5 face each other, and electrical discharge is repeatedly performed.

Further, the relative movement between the wire electrode 1 and the workpiece 5 is performed by a drive motor 10 that operates an Processing such as cutting out the shape is performed.

Here, the progress of machining in the wire-cut electrical discharge machining apparatus will be explained with reference to FIG.

The electric discharge between the wire electrode 1 and the workpiece 5 in the direction indicated by the arrow P in the figure can be roughly divided into an A part and a B part.

Considering the state of electrical discharge machining in part A, wire electrode 1
The discharge is repeated between the workpiece 5 and the workpiece 5 at a distance of the discharge gap g.

The discharge energy at part A is consumed as the wire electrode 1 moves in the direction of arrow P in the figure.

Therefore, the magnitude of the discharge energy greatly influences the machining progress speed.

Next, in the state of electrical discharge machining in section B, the electrical discharge is repeated across the discharge gap g, similar to that in section A, and the machining progresses in a direction perpendicular to arrow P.

That is, the discharge energy in the discharge at part B is consumed to form the machined groove width S, which is twice the discharge gap g plus the diameter of the wire electrode 1.

Therefore, the magnitude of the discharge energy at portion B greatly influences the magnitude of the machined groove width S.

However, in reality, the discharge energy of parts A and B is not supplied independently, but is supplied between the wire electrode 1 and the workpiece 5.

As a result, discharge energy is distributed between part A and part B.

In wire-cut electric discharge machining, in order to increase the machining speed, it is necessary to increase the discharge energy in section A and to decrease it in section B.

In other words, as much of the supplied energy as possible needs to be consumed in part A.

Furthermore, in terms of machining accuracy, the machining groove width S needs to be constant, so the discharge energy at section B must be constant.

In short, in order to increase the machining speed, the energy supplied to section A must be increased and the energy supplied to section B must be decreased.

And the meaning of maintaining the machining speed obtained in this case,
In order to keep the machining groove width S constant, the distribution of discharge energy in the above A and B sections must be maintained constant.

The machining conditions set in wire cut electrical discharge machining have been described above.

Next, we will discuss the problems with conventional machining conditions.

As shown in FIG. 3, when the wire electrode 1 is moving in the direction indicated by the arrow Q in the figure, the wire electrode 1 is actually in a vibrating state, and there is a considerable amount of excess energy compared to the case in FIG. Processing is being carried out.

The reason why the wire electrode 1 vibrates in this way is due to the fourth
As shown in the figure, when an electric discharge occurs between the wire electrode 1 and the workpiece 5 in the R1 section, ionization progresses in the vicinity and the area becomes very susceptible to dielectric breakdown, so that a subsequent electric discharge occurs.

In other words, discharge occurs in groups in the R1 portion.

Next, since the machining liquid 7 flows toward the center of the workpiece 5, the discharge group in the R1 section as described above is divided into R1, R2 as shown in FIG. ,R
3° Move to R4 and R5 sections.

In this case, although not necessarily in the numerical order in the figure, the center of the workpiece *5 has the most ions, and the machining chip also has poor discharge conditions at the center, so a group of discharges naturally flows to the center. concentrate.

This is also evidenced by the fact that the machined cross section, which is unique to wire-cut electrical discharge machining, is hollow.

In short, the repulsive force applied to the wire electrode 1 due to the gas explosive force during the discharge by the discharge group from R1 to R5 becomes an excitation force, and the wire electrode 1 vibrates.

In other words, the discharge group is a forced vibration force, and its movement is a forced vibration frequency.

Additionally, fluctuations in the tension applied to the wire electrode 1 may aggravate the vibrations.

Since the wire electrode 1 vibrates in this manner, it is possible to imagine a pseudo wire electrode 12 whose cross section is considered to be equivalent to the vibration range, as shown in FIG.

Therefore, since the diameter of the pseudo wire electrode 12 is larger than the diameter of the actual wire electrode 1, the discharge energy at section B1 in FIG. 3 inevitably becomes larger than the discharge energy at section B in FIG.

Comparing FIG. 2 and FIG. 3, the following relationship holds true for the same energy supply.

Diameter of pseudo wire electrode 12>Diameter of wire electrode 1, ", B,
Discharge energy in section B > Discharge energy in section B, °, Machining groove width S1 > Machining groove width S Therefore, discharge energy in section A1 <Discharge energy in section A, °, Machining speed in the case of Fig. 3 <In Fig. 2 Machining speed (direction of arrow Q) (direction of arrow P) Because the wire electrode 1 is vibrating in this way, it is originally
The discharge energy that should be consumed in the A1 part of the diagram is B1.
This increases the machining groove width S1.

In other words, the vibration of the wire electrode 1 greatly reduces the processing efficiency.

In order to prevent this, a method can be considered in which the wire electrode 1 is held between dampers.

This will be explained using FIG. 6.

FIG. 6a is a partially cutaway sectional view, and FIG. 6 is a top view of the nozzle outlet and a sectional view taken along the line CC' shown in FIG. 6a.

FIG. 6C is a top view of the nozzle spout, and in the figure, 1 is a wire electrode running in the direction of the arrow, 3 is a lower wire guide, 6 is a machining liquid nozzle, and 13 is formed of rubber or the like and is inside the machining liquid nozzle 6. It's a damper fitted into the damper.

When the wire electrode 1 is moved in the direction of the arrow to relatively move the workpiece 5 and the wire electrode 1 for processing, the wire electrode 1 is placed above the lower wire cut 3, inside the processing liquid nozzle 6, and at the sixth position. Processing fluid nozzle 6 as shown in Figure C
Since the workpiece is held by the damper 13 in the closed state, the workpiece is processed into the desired shape.

At this time, vibrations generated in the wire electrode 1 are absorbed by the damper 13.

However, due to the nature of the damper 13 sandwiching the wire electrode 1,
It is difficult to avoid using materials that are highly prone to wear.

Furthermore, it has the disadvantage that the damper 13 tends to obstruct the flow of the machining fluid 7.

This idea was made in consideration of these points,
An object of the present invention is to provide a wire-cut electrical discharge machining device that can suppress vibration of a wire electrode without interfering with the flow of machining fluid, has a high machining speed, and has high machining accuracy.

This invention is based on a wire electrode 1 that vibrates in primary mode and multi-order mode, as shown in the principle diagram of FIGS. 5a and 5b.
are held in contact with each other by a pin 14 disposed between the upper wire guide 2 and the lower wire guide 3, thereby suppressing vibration of the wire electrode 1.

An embodiment shown in FIG. 7 will be described below.

FIG. 7a is a partially cutaway sectional view, and FIG. 7 is a top view of the nozzle outlet and a DD' sectional view shown in FIG. 7a.

FIG. 7C is a top view of the nozzle outlet.

In the figure, the same reference numerals as in FIG. 6 indicate the same or corresponding parts.

Reference numeral 14 denotes a thin wire-shaped pin made of ceramic or the like and fitted into the processing liquid nozzle 6.

Therefore, the pin 14 is provided in the machining fluid nozzle 6 disposed in the machining part 4 of the workpiece 5, that is, in the position closest to the gap between the wire electrode 1 and the workpiece 5, and is provided in the lower wire guide 3.
It will be provided on the gap side.

In such a configuration, when processing is performed by moving the wire electrode 1 in the direction of the arrow to move the workpiece 5 and the wire electrode 1 relatively, the wire electrode 1 is connected to the processing fluid nozzle 6 above the lower wire guide 3. and with the machining fluid nozzle 6 closed as shown in FIG.
contact by.

That is, by disposing the pin 14 further inside between the upper wire guide 2 and the lower wire guide 3, the distance between the supporting points of vibration of the wire electrode 1 becomes narrower, and as a result, the workpiece is machined. Vibrations generated in the wire electrode 1 are suppressed by the pin 14.

FIG. 8 is a characteristic curve diagram obtained through experiments to compare machining speeds when using the pin 14, when using the damper 13, and when using the conventional method.

The horizontal axis is the thickness t of the workpiece, and the vertical axis is the processing speed F (
mm/m1n), and 17 represents pin 1 according to this invention.
4 is used, 16 is the characteristic curve for the case using the damper 13 in FIG. 6, and 15 is the characteristic curve for the conventional case in FIG.

It can be seen from these characteristic curves 15 to 17 that the machining speed according to this invention is 1.7 to 1.8 times faster than conventional machining in the range of thin plate thickness, as in the case of the tamper type.

Although the case where the pin 14 is provided on the lower wire guide 3 has been described above, it may also be provided on the upper wire guide 2.

Furthermore, they may be provided on both sides, and in this case, the vibration isolation effect is further improved.

Further, the cross-sectional shape of the pin may be any shape as long as it does not damage the wire electrode.

As described above, in this invented device, a pin is provided inside at least one of the upper and lower parts of the machining fluid nozzle on the gap side with respect to the wire guide.

Since the wire electrode is held in contact with this pin, the pin is placed inside the machining liquid nozzle closest to the machining part and at a position closest to the machining part, which obstructs the flow of machining fluid. Furthermore, since the span of wire vibration is short, the vibration of the wire electrode is sufficiently suppressed, which improves the ejection condition of machining chips at the center of the workpiece, and improves machining speed and machining accuracy. It has the effect of further improving.

[Brief explanation of the drawing]

Figure 1 shows a conventional wire-cut electric discharge machining device, Figure a is an overview diagram showing its configuration, Figure B is a sectional view of the main part showing the details of the machining section, and Figure 2 is the ideal process of machining. Figure 3 is a diagram showing the progress of conventional machining, Figure 4 is a diagram showing the state.
Figure 5 is an explanatory diagram of the vibration process of the wire electrode, Figure 5 is a diagram of the principle of this invention, Figure 6 shows the configuration of a single damper type, figure a is a partially cutaway sectional view, figure b is the top view of figure a above. Figures and C-C
' sectional view, Figure 0 is a top view, Figure 7 shows an embodiment of this invention, Figure A is a partially cutaway sectional view, Figure B is a top view of Figure A and a sectional view taken along line DD', 0. The figure is a top view, and FIG. 8 is a characteristic curve diagram showing the relationship between the plate thickness t of the workpiece and the machining speed. In the figure, 1 is a wire electrode, 3 is a lower wire guide,
6 is a processing liquid nozzle, and 14 is a pin. The same reference numerals in the figures indicate the same or corresponding parts.

Claims (2)

[Scope of utility model registration request] (1) A continuously supplied wire electrode is supported by two upper and lower wire guides, and the wire electrode and the workpiece are opposed to each other with a minute gap between the upper and lower wire guides, and the wire guide is built in and the workpiece is In a wire-cut electrical discharge machining device that performs machining by relatively moving the wire electrode and the workpiece by supplying machining fluid to the gap from a machining fluid nozzle placed close to the gap, A wire-cut electric discharge machining apparatus characterized in that a pin is provided inside at least one of the machining fluid nozzles on the side of the gap from the wire guide, and the wire electrode is held in contact with the pin. (2) The wire-cut electric discharge machining apparatus according to claim 1, wherein the pin is made of ceramic.