JPS6336890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire-cut electric discharge machining device, and in particular, a machining process is performed between the wire electrode and the workpiece while supplying machining liquid to a minute gap where the wire electrode and the workpiece face each other. The present invention relates to a wire cut electric discharge machining apparatus which is used mainly for processing such as punching and cutting of general molds by applying a voltage using a power source and repeatedly generating electric discharge between the two.

FIG. 1 shows the configuration of a wire guide mechanism that guides and supports a wire electrode in a conventional wire-cut electrical discharge machining apparatus. The wire electrode 10 is connected to the workpiece 1
Wire guides 14a, 14 arranged above and below 2
b, and is opposed to the workpiece 12 at the processing section 16. The machining fluid (generally pure water passed through an ion exchange resin) 20a, which is jetted from the upper and lower machining fluid supply nozzles 18a and 18b,
Using 20b as a medium, electric discharge is repeatedly performed in the machining section 16 with a pulse current from a machining power source (not shown).

The distance l between the upper and lower wire guides 14a, 14b and the upper and lower surfaces of the workpiece 12 (hereinafter l is referred to as wire guide span) is 20 to 30 mm. Generally, wire electrodes 10 with a diameter of 0.05 to 0.3 mm are most often used, and the materials are copper, brass, etc.
Materials such as tungsten are used.

In the wire cut electrical discharge machining apparatus having such a configuration, during electrical discharge machining, the wire electrode 10 is generally said to vibrate due to the repulsive force caused by the gas explosive force during electrical discharge. Therefore, as shown in FIG _. 2, in an ideal state without vibration as shown in FIG. If overcut occurs in the side direction perpendicular to the machining progress direction due to the vibration of the wire electrode 10, the machining groove width will decrease.
It expands to S ₁ . Naturally, since the energy supplied from the processing power source is constant, the second
Comparing figures a and b, the width of the machined groove is S ₀
<S ₁ , regarding the machining feed rate of the wire electrode 10
It is obvious that there is a relationship F ₀ >F ₁ .

That is, in the conventional wire guide mechanism having the configuration shown in FIG. 1, due to the vibration of the wire electrode 10,
Theoretically, it can be seen that the machining feed rate becomes slower. Figure 3 shows experimental proof of this. FIG. 3 shows the relationship between the machining feed rate F on the vertical axis and the guide span l on the horizontal axis. As shown in the figure, the smaller the guide span l, the higher the machining feed rate. This indicates that the state shown in FIG. 2b approaches the state shown in FIG. 2a due to an increase in vibration frequency and a decrease in amplitude due to a decrease in the guide span l. According to experiments conducted by the inventor, it has been found that the minimum value of the guide span l is approximately 5 mm, taking into consideration the supply of machining fluid.

In this way, it has been found that reducing the guide span l leads to an increase in the machining feed rate.However, as a mounting problem, the upper and lower wire guides 14a and 14b are moved closer to the workpiece surface. Examples of such problems include a decrease in operability and difficulty in jetting out the machining fluids 20a and 20b coaxially with the wire electrode 10.

For this reason, in order to increase the machining feed speed, a configuration was considered that suppressed the vibration of the wire electrode, and
- There is one shown in specification No. 91793. What is shown in this specification further includes a guide pin 13 between the wire guides 2 and 3 provided on both sides of the workpiece.
are provided respectively to prevent vibration of the wire electrode. In this configuration, since the guide pin 13 is literally pin-shaped, the wire guides 2 and 3 and the guide pin 13 cannot be accurately aligned when the wire electrodes are arranged in a straight line. There was a problem in that the wire electrodes were arranged in a slightly bent manner. Also,
In order to suppress the vibration of the wire electrode, it is necessary to reduce the distance between the wire guides 2 and 3 and the guide pin 13, but in the configuration shown in this specification, the installation and fixation of the guide pin 13 is difficult. There was a problem that it was not possible to set it to a smaller value.

This invention was made in view of the above-mentioned problems with the conventional device, and it has a simple configuration and is easy to manufacture, without changing the operability of the conventional device or the method of ejecting machining fluid, and makes the wire electrode straight. It is an object of the present invention to provide a wire cut electric discharge machining apparatus having a wire guide assembly that can be easily arranged and that can suppress vibration of a wire electrode.

In order to achieve the above object, the present invention provides a wire guide assembly for guiding and supporting a wire electrode.
The wire guide assembly is disposed on one side or both sides of the workpiece, and includes a first fixed body that surrounds and fixes a first die guide in which a wire electrode passage hole is formed, and this first fixed body. a second fixing body that surrounds and fixes a second die guide in which a wire electrode passage hole is formed; Second
The fixed body of the die guide is fitted to maintain a predetermined distance between the first and second die guides.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. FIG. 4 is a diagram for explaining the propagation state and mode of vibration of the wire electrode 10.
Figure a shows the case of first-order mode vibration, and the wire electrode 10 forms nodes between the upper and lower wire guides 14a and 14b. At this time, the frequency is a and the amplitude is A _a . Next, Fig. 4b shows a case of vibration having an n-th mode, and the frequency is _b and the amplitude is A _b , as in Fig. 4a. At this time, _a < _b and A _a > A _b .
Next, as shown by the arrow _c in FIG. When the part becomes a node of vibration, the vibration is transmitted without being attenuated. Since such low frequency vibrations have large amplitudes, they promote the vibrations of the wire electrode 10, as shown in FIG. 2b. Therefore, as shown in Fig. 4b, external vibrations and internal vibrations due to discharge (herein, inside and outside mean between the two wire guides 14a and 14b or outside thereof) are also converted into higher-order mode vibrations. It can be seen that if this is done, the current state shown in Figure 2a will be approached.

The present invention is a wire cut electric discharge machining apparatus having a wire guide mechanism having the function of increasing the vibration of the wire electrode 10 in this manner. FIG. 5 shows a principle diagram of the apparatus of the present invention, in which two first to fourth die guides 22a to 22d, each having a passage hole for the wire electrode 10, are placed on the upper side of the workpiece 12. 22b, 2 pieces on the bottom 22c, 22
A first die guide 22a, a second die guide 22a,
22b and the third and fourth die guides 22c,
The distance between the supporting points of the wire electrodes 10 between the wire electrodes 22d is 5 mm. In this way, by supporting the wire electrodes 10 at two points on the upper and lower sides of the workpiece 12, which are close to point contact, the transmitted waves of the vibrations of each part can be reduced to a height that is equal to half a period or n periods between the two points of support. Only those of the next mode are used, and for other low frequency ones, the first to fourth dice guides 22
a to 22d exert a damping effect. Further, regarding internal vibrations due to discharge, the reflected waves are of high order, and therefore act in a direction that forcibly suppresses the wire vibrations. By increasing the vibration of the wire electrode 10 in this way, it approaches the ideal state shown in FIG. resolved in time.

FIG. 6 shows a specific example of a wire guide assembly to be applied to the wire-cut electrical discharge machining apparatus of the present invention, in which the first and second die guides are made of a highly wear-resistant material such as diamond or sapphire. 22a, 22b are embedded in sintered bodies 24a, 24b, and these sintered bodies 24a, 24b are fixed to first and second fixed bodies 26a, 26b with adhesive or the like. Dice guides 22a, 22
b・Sintered bodies 24a, 24b・Fixed bodies 26a, 26
At the center of b are passage holes 28a, 30a, 32a and 28b, 30b, through which the wire electrode 10 passes.
32b is formed, and this first fixed body 26
Passing holes 28a, 30a, 32a on the a side and passing holes 28b, 30b, 3 on the second fixed body 26b side
2b is tapered outward to make it easier for the wire electrode 10 to pass through. The diameter of the hole in each die guide 22a, 22b is increased by 0.01 mm from the diameter of the wire electrode 10, and the contact length between the die guide 22a, 22b and the wire electrode 10 is 0.5 mm. There is. This value was chosen experimentally. Then, the pair of first and second fixed bodies 26a and 26b configured in this way are
As shown in FIG. 7, the wire guide assembly 34 is constructed by fitting them together in a separable manner. In this case, the wire guide assembly 34 is constructed by fitting the fitting portions of the first and second fixing bodies 26a and 26b, respectively, and by this fitting, the first and second die guides 2
The centers of 2a and 22b are accurately aligned,
The distance between each die guide 22a, 22b can be set small. Further, the outer peripheries of the two fixed bodies 26a and 26b that are fitted have a continuous tapered shape. The reason why the wire guide assembly 34 is divided into the two fixed bodies 26a and 26b is to eliminate manufacturing difficulties.

FIG. 8 shows a wire guide assembly 34 having this configuration.
This shows a wire guide mechanism to which the wire guide assembly 34 is inserted into the center tapered hole 40 of a mounting plate 38 suspended horizontally in the mounting main body box 36, and a presser bolt 42 screwed into the mounting main body box 36 is used. The wire guide assembly 34 is fixed to the mounting plate 38 by pressing the larger diameter side of the wire guide assembly 34. Lower chamber 36a of the mounting body box 36 partitioned by the mounting plate 38
Processing fluid 20a supplied through pipe 44 to
The mounting body box 36 is inserted through the hole 46 of the mounting plate 38.
It reaches the upper chamber 36b of the mounting body box 36, and is ejected from the hole 48 in the center of the mounting main body box 36 toward the processing section of the workpiece.

Figure 9 shows the relationship between the two, with the vertical axis representing the machining feed rate F and the horizontal axis representing the guide span l. As mentioned above, in the conventional wire guide mechanism (shown by the dotted line), the guide span l is large. In contrast, in the wire guide mechanism applied to the device of the present invention configured as shown in FIG. Little has changed. In addition, in the conventional wire guide mechanism, even if the guide span l is small, depending on the workpiece, if the actual machined part has a change in thickness at both the top and bottom of the workpiece, or even on one side, it is necessary to Therefore, the guide span l may become large, and in this case, the machining feed rate F decreases as described above. However, the wire guide mechanism having the configuration shown in FIG. 8 does not reduce the machining feed rate even in the above case, and can prevent a decrease in the machining feed rate in all machining areas and types.

Figure 10 shows the same guide span l (l = 20~30
This is a comparison diagram of the machining feed rate F of the conventional device (indicated by dotted line) and the device of the present invention (indicated by solid line) in mm), and it can be seen that there is a large difference over the entire thickness T of the workpiece. .

In the above embodiment, wire guide assemblies are placed on both sides of the workpiece, but the same result can be obtained if only one side has a wire guide assembly and the other side has one die guide. The effect was obtained. In addition, in this device, in order to propagate the vibration in a higher order mode, it goes without saying that the closer the wire guide itself is to point contact, the greater the effect, and the narrower the interval between the two die guides, the higher the order can be achieved. The diameters of the holes in the two die guides are desirably chosen to be as large as 2 μm relative to the diameter of the wire electrode, in order to eliminate directionality as much as possible and to provide fixed boundary ends. Furthermore, although this device is effective even when the guide span l is large, in order to reduce the amount of deflection of the wire electrode, it is necessary to
It is preferable to make it smaller in terms of processing accuracy.

As described above, the present invention provides a wire guide assembly as a wire guide mechanism for a wire-cut electrical discharge machining apparatus, which has a die guide close to at least two wire electrodes on one or both sides of a workpiece and in close contact with the wire electrodes. Therefore, the vibration of the wire electrode becomes a higher-order mode, the vibration frequency is increased, the amplitude is decreased, and concentrated discharge etc. can be prevented over time. As a result, the effect of increasing the machining feed rate of the wire electrode is obtained.

Furthermore, the wire guide assembly according to the present invention is composed of a pair of fixed bodies, and a die guide is fixed to each fixed body, so that the wire guide assembly has a simple structure and is easy to manufacture. A wire guide assembly is constructed by fitting the parts together,
The centers of each die guide can be accurately and easily aligned, the wire electrodes can be easily arranged in a straight line, and since the die guides are fixed to a fixed body, the distance between the die guides can be adjusted depending on the fixed state. This has the effect of easily making it smaller.

[Brief explanation of the drawing]

Figure 1 is a front view of a conventional wire guide mechanism, Figure 2 is an explanatory diagram of the vibration of the wire electrode due to the wire guide mechanism, and Figure 3 is the relationship between the wire guide span and machining feed rate of the wire guide mechanism in Figure 1. FIG. 4 is an explanatory diagram of the propagation state and mode of wire electrode vibration, FIG. 5 is an explanatory diagram of the principle of the device of the present invention, and FIG. 6 is a sectional view of the wire guide assembly applied to the device of the present invention. , FIG. 7 is an exploded view of the wire guide assembly, FIG. 8 is a vertical sectional view showing a specific example of the wire guide mechanism applied to the device of the present invention, and FIG.
The figure is a curve diagram showing the relationship between the guide span and machining feed rate between the conventional device and the device of the present invention, and Figure 10 is the relationship between the machining feed rate when the thickness of the workpiece is changed between the conventional device and the device of the present invention. FIG. The same members in each figure are given the same reference numerals, 10 is a wire electrode, 12 is a workpiece, 14a, 14b are wire guides, 16 is a processing section, 18a, 18b is a processing fluid supply nozzle, 20a, 20b is processing liquid, 22
a to 22d are first to fourth die guides, 24
a, 24b are sintered bodies, 26a, 26b are first and second fixed bodies, 28a, 28b, 30a, 30b,
32a and 32b are passing holes, 34 is a wire guide assembly, 36 is a mounting body box, 38 is a mounting plate, 40 is a tapered hole, 42 is a holding bolt, 44 is a pipe, 4
6 and 48 are holes.

Claims (1)

[Scope of Claims] 1. While supplying machining liquid to the opposing micro-gap between the wire electrode and the workpiece, a voltage is applied between the wire electrode and the workpiece using a machining power source, and the voltage is applied between the two. In a wire cut electric discharge machining apparatus that performs machining by repeatedly generating electrical discharge, a wire guide assembly that guides and supports the wire electrode is disposed on one or both sides of the workpiece, and the wire guide assembly A first fixing body that surrounds and fixes a first die guide in which a wire electrode passage hole is formed, and a fitting part that fits into a fitting part provided on the first fixing body. , a second fixing body that surrounds and fixes the second die guide in which the wire electrode passage hole is formed; A wire cut electrical discharge machining apparatus characterized in that the die guides are configured to maintain a predetermined distance from each other. 2. The wire-cut electric discharge machining apparatus according to claim 1, wherein the distance between each die guide of the first and second fixed bodies is set to 5 mm or less.