JP2000126940A - Pipe electrode holder of superfine pipe electrode for electric discharge machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily insert/fix a superfine pipe electrode into a collet as it is by inserting an inserting jig into the collet and a rubber bush. SOLUTION: Until the large diameter step part 11b of an inserting jig 11 abuts to the lower end surface of a collet 2, the inserting jig 11 is inserted into a tool installing hole 2h of the collet 2 so that a rubber bush 5 is pushed in the tip of the inserting jig 11. A superfine pipe electrode 7 is introduced along the taper surface 11e of a through hole 11h of the inserting jig 11 so that this pipe electrode 7 is inserted until the tip projects from the upper end of the rubber bush 5. Thus, the inserting jig 11 into which this pipe electrode 7 is inserted, the rubber bush 5 and the collet 2 are installed in a collet holder 3 to be fastened by a collet nut 4. Since the rubber bush 5 compresses both of this pipe electrode 7 and the inserting jig 11 in sealing a work liquid, a fear of leaking the work liquid supplied by a supply cylinder 6 can also be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for holding a pipe electrode of a small-hole electric discharge machine, and more particularly to an improvement in an apparatus for holding an extremely fine pipe electrode by a collet chuck.

[0002]

2. Description of the Related Art A small hole electric discharge machine for electric discharge machining of a small hole in a workpiece is widely used. This small hole electric discharge machine
A small-diameter, long pipe electrode is attached to a pipe electrode holding device including a collet chuck attached to the lower end of the processing head, and a working fluid is fed into the pipe electrode and a predetermined gap is formed between the workpiece and the pipe electrode. The pipe electrode is advanced with respect to the workpiece while applying a pulse current for electric discharge machining, and a deep hole having a fine diameter is machined.

[0003] The hole to be machined by this small hole electric discharge machine is
With the miniaturization of equipment, there has recently been a demand for smaller diameters.
Along with this, the outer diameter of the pipe electrode used has been increasingly smaller. At present, the pipe electrode used for practical use is, for example, a thin one having an outer diameter of φ0.15 m.
m, inner diameter φ 0.07 mm, outer diameter φ 0.1 mm,
There are those with an inner diameter of about 0.04 mm, and those with a minimum outer diameter of up to an outer diameter of 0.08 mm. Moreover, its length is as long as about 200 to 350 mm. Such a very thin pipe electrode is extremely bendable and easily broken, and therefore requires careful handling. However, it is extremely difficult to mount the pipe electrode on an electric discharge machine.

A pipe electrode holding device for attaching and detaching a pipe electrode to and from an electric discharge machine usually includes a collet chuck 1 as shown in FIG. The collet chuck 1 includes a collet holder 3 mounted on a processing head (not shown), a collet 2 for gripping a pipe electrode 7, and a collet nut 4 for tightening the collet 2, similarly to a known collet chuck. Except for the upper end, the collet 2 has a tool mounting hole 2 similar to a known collet for attaching and detaching a tool.
h, a slit 2s, and a tapered surface 2a. In addition, in the small-hole electric discharge machine, a supply cylinder 6 for supplying a machining liquid required for electric discharge machining to a pipe electrode, and a rubber bush 5 for sealing the machining liquid are incorporated in the collet holder 3. The rubber bush 5 is disposed between a tapered seat 6 a provided at a lower end of the supply cylinder 6 and a tapered seat 2 b provided at an upper end of the collet 2, and has a through hole 5 h formed at the center of the rubber bush 5. Are positioned so as to coincide with the center of the tool mounting hole 2h of the collet 2. The pulse current for electric discharge machining is supplied from a power supply device (not shown) to the collet holder 3.
Is supplied to the collet 2 via the. In FIG. 6, the dimension in the direction (lateral width direction) perpendicular to the center of the collet chuck 1 is shown enlarged with respect to the dimension in the center direction.

In such a configuration, the pipe electrode 7
Is inserted through the collet 2 and the rubber bush 5,
It is attached so that the tip protrudes above the rubber bush 5. When the collet nut 4 is screwed into the collet holder 3, the collet 2 pushed into the tapered hole 3 a of the collet holder 3 tightens and fixes the pipe electrode 7. Further, the rubber bush 5 is compressed by the pressing force generated between the collet 2 and the supply cylinder 6 when the collet nut 4 is tightened, and the through hole 5h of the rubber bush 5 is reduced.
Adheres to the pipe electrode 7. In this way, the pipe electrode 7 is fixed, and the machining liquid supplied from the through hole 6b of the supply cylinder 6 is supplied to the pipe electrode 7 without leaking outside.

However, if the outer diameter of the pipe electrode 7 is extremely small, the pipe electrode 7 is sandwiched between the slits 2s of the collet 2 when the pipe electrode 7 is mounted on the collet 2.
Its insertion is very difficult. And even after the insertion, when the collet nut 4 is tightened, the pipe electrode 7 is often misaligned, and is often sandwiched again by the slit 2s and collapsed. Further, it was impossible to directly hold the pipe electrode with the collet 2 with an extremely thin pipe electrode. As described above, it is extremely difficult or impossible to mount a micro pipe electrode.

Therefore, a method of forming a shank portion by bonding or welding a reinforcing pipe to the end of such a very thin pipe electrode and mounting the pipe electrode with the shank on an electric discharge machine is adopted. Sometimes. In this case, the outer diameter of the shank portion is naturally formed to be an outer diameter that can be easily attached to and detached from the collet, for example, about 1 mm.

[0008]

However, attaching a reinforcing shank to an ultra-thin, thin-walled pipe electrode requires special techniques. In addition, techniques for securing conductivity and sealing a high-pressure working fluid are also required. Because of the necessity, the above-mentioned special pipe electrode with a shank has not been mass-produced at present.
Therefore, even if such a pipe electrode with a shank becomes insufficient, you have to make it yourself,
Processing of ultra-fine holes was very difficult and had to be expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make it possible to easily insert an ultrafine pipe electrode into a collet as it is, and to securely fix the ultrafine pipe electrode. Another object of the present invention is to provide a pipe electrode holding device in which leakage of a supplied working fluid is reliably suppressed.

[0010]

According to the present invention, there is provided a pipe electrode holding apparatus for an ultra-fine pipe electrode for electric discharge machining, wherein (1) a pipe electrode for holding a pipe electrode 7 so as to be able to conduct electricity and supplying a machining fluid to the pipe electrode 7 In the holding device, a collet chuck 1 including a collet 2, a supply cylinder 6 for supplying a processing liquid to a pipe electrode 7, a rubber bush 5 arranged between the collet 2 and the supply cylinder 6, and a detachable attachment to the collet 2. And an insertion jig 11 capable of inserting the pipe electrode 7.

Further, another aspect of the present invention is a pipe electrode holding apparatus for an ultra-fine pipe electrode for electric discharge machining. (2) In the pipe electrode holding apparatus described in the above (1), the insertion jig 11 has a large outer diameter. 11a is formed so that it can be inserted into the tool mounting hole 2h of the collet 2 and has an outer diameter that can be fixed, and a step 11b having a larger diameter at one end and a step 11c having a smaller diameter at the other end. Alternatively, a tapered surface 11d is formed, and a through hole 11h whose inner diameter is slightly larger than the outer diameter of the pipe electrode 7 is formed at the center thereof, and when the insertion jig 11 is inserted into the rubber bush 5, The insertion jig 11 is formed to have a length that allows the rubber bush 5 to be inserted into the rubber bush 5 except for a margin L2 for fixing the pipe electrode 7.

Further, another aspect of the present invention is a pipe electrode holding device for an ultra-fine pipe electrode for electric discharge machining. In the above, the pipe electrode holding device includes a collet chuck 1 including a collet-like jig 21 and a collet holder 3 similar to a collet, a supply cylinder 6 for supplying a processing liquid to the pipe electrode 7, a collet-like jig 21, The collet-like jig 21 includes a rubber bush 5 disposed between the cylinders 6, and the collet-like jig 21 has a through hole 21 h into which the pipe electrode 7 can be inserted, and a tapered surface 21 a that contacts the tapered hole 3 a of the collet holder 3. The rubber bush 5 is formed to have a length to be inserted into the rubber bush 5 except for the interference L2 for fixing the pipe electrode 7 and the tapered seat 21b on which the rubber bush 5 is placed. And a protruding pipe 21c.

[0013]

1 to 4 show a first embodiment and a second embodiment.
1 is an embodiment showing a pipe electrode holding device for an ultrafine pipe electrode for electric discharge machining according to the present invention. Components that are the same as the conventional collet chuck described in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. 1 is an assembled sectional view showing a state in which an insertion jig into which a very fine pipe electrode is inserted is mounted on a collet chuck, FIGS. 2 and 3 are sectional views of the insertion jig, and FIG. It is a schematic diagram explaining a state and a liquid sealing state. In these figures, the direction perpendicular to the center of the collet chuck (width direction)
Are enlarged with respect to the dimension in the center direction.

The structure of the collet chuck 1 itself in FIG. 1 is the same as that of the collet chuck 1 described in FIG. 6 is different from FIG. 6 in that an insertion jig 11 is inserted into the collet 2 instead of the ultrafine pipe electrode 7. Although the mechanism for tightening the collet is exemplified by a mechanism for tightening with a collet nut, it should be noted that a mechanism for tightening the collet other than the collet nut can similarly employ the insertion jig of the present invention. .

As shown in FIG. 2, the insertion jig 11 has an outer diameter that can be fixed so that the outer diameter of a region 11a occupying most of the insertion jig can be easily inserted into the tool mounting hole 2h of the collet 2. For example, it is formed to about φ1 mm. At one end of the insertion jig 11, a step portion 11b having a larger diameter is formed, and at the other end, a step portion 11c having a smaller diameter is formed. here,
The small-diameter step portion 11c has a tapered surface 11d as shown in FIG.
It may be. Since the difference in diameter between the step 11c and the region 11a is about 0.4 mm, there is not much difference between the step processing and the taper processing. Then, the length between the region 11a and the small-diameter step portion 11c or the region 11a and the tapered surface 11d
The total length L1 is formed to a length as described in FIG. The material of the insertion jig 11 is the collet 2
(Cu), copper-tungsten alloy (UuW) or the like is selected to supply a pulse current for electric discharge machining to the pipe electrode 7 from.

A through hole 11h having a predetermined inner diameter D into which the ultrafine pipe electrode 7 can be inserted is formed at the axial center of the insertion jig 11 so as to coincide with the center thereof. A tapered surface 11e is formed at the opening of the through hole 11h where the pipe electrode 7 is inserted. The inner diameter D of the through hole 11h is set so that the pipe electrode 7 can be energized.
The gap with is minimized. For this reason, the insertion jig 11 is selectively used depending on the outer diameter of the pipe electrode 7 to be attached and detached. For example, φ0.2 to φ0.15 mm
The insertion jig 11 having an inner diameter of φ0.22 mm is used for the pipe electrode 7, and the insertion jig 11 having an inner diameter of 0.17 mm is used for the pipe electrode 7 having a diameter of about φ0.15 to φ0.08 mm or less. . Of course, it is most preferable to arrange the insertion jigs 11 having the through holes 11h having the inner diameter D corresponding to the respective outer diameters of the pipe electrode 7. In this way, the pipe electrode 7 enters the through hole 11h of the insertion jig 11, and the pulse current for electric discharge machining passes from the collet 2 through the insertion jig 11,
Power is supplied to the pipe electrode 7. In addition, when the pipe electrode 7 rotates during processing, the core of the pipe electrode 7 is prevented from swinging. In addition, in supplementing this runout, in the small hole electric discharge machine, the guide electrode (not shown) separately provided near the workpiece is sandwiched by the pipe electrode, and the runout of the pipe electrode is further suppressed. I have.

The pipe electrode 7 is fixed as shown in FIG. 4. First, the positional relationship between the components shown in FIG. 4 will be described. When the tip of the insertion jig 11 is inserted into the rubber bush 5, the length of the insertion jig 11 is set so that the distance L2 from the tip of the insertion jig 11 to the upper end of the rubber bush 5 is, for example, about 2 mm. L1, the entire length of the rubber bush 5 and the entire length of the collet 2 are formed. By doing so, when the rubber bush 5 is compressed when the pipe electrode 7 is fixed, the rubber bush 5 is deformed unevenly and the through hole 5
This prevents the pipe electrode 7 from being bent out of alignment with the through hole 11h of the insertion jig 11 and bending the pipe electrode 7. Note that the distance L
Numeral 2 depends on the hardness and length of the rubber bush 5 and the compressive force applied to the rubber bush 5 when the pipe electrode 7 is chucked, but is determined in accordance with them.

In the above configuration, the pipe electrode 7
Is fixed to the pipe electrode holding device as follows.
First, the insertion jig 11 is inserted into the tool mounting hole 2h of the collet 2 until the large-diameter step portion 11b of the insertion jig 11 contacts the lower end surface of the collet 2, and the rubber bush 5 is attached to the tip of the insertion jig 11. Push in. Then, insert the pipe electrode 7 into the insertion jig 11.
The pipe electrode 7 is inserted until its tip projects from the upper end of the rubber bush 5. Thus, the pipe electrode 7 was inserted,
The insertion jig 11, the rubber bush 5, and the collet 2 are assembled to the collet holder 3, and tightened with the collet nut 4. Then, the pipe electrode 7 is connected to the section L of the rubber bush 5.
It is fastened at the part 2 and fixed to the pipe electrode holding device.

In the present invention, the tightening force of the pipe electrode 7 by the rubber bush 5 is not strong at all, but since the wall thickness of the pipe electrode is thin, this weak tightening force is sufficient. In other words, since the area of the end face of the microfine pipe electrode 7 is small, the axial force applied to the pipe electrode is small even if the jet pressure of the machining liquid applied to the tip face of the microfine pipe electrode is high. The electrodes are fixed. As for the seal of the working fluid, since the rubber bush 5 compresses both the pipe electrode 7 and the insertion jig 11,
Concerns about leakage of machining fluid have been eliminated. Particularly, a small-diameter stepped portion 11c or a tapered surface 11d is provided at the tip of the insertion jig 11.
Is formed, the rubber bush 5 abuts on the pipe electrode 7 and the tip of the insertion jig 11 in a smooth curve, and the tightening pressure of the rubber bush 5 on the pipe electrode 7 and the insertion jig 11 is reduced. Be even. Thus, the pipe electrode 7 is securely fixed, and the seal between the pipe electrode 7 and the insertion jig 11 is completed.

The insertion jig 11 is attached to the collet 2
Since the operation and effect are exhibited by the configuration in which the device 1 is mounted, another embodiment as shown in FIG. 5 can be adopted. Instead of the insertion jig 11 and the collet 2, a collet-like jig 21 in which these are integrated is attached. In this case, the collet-like jig 21 is inserted into the collet 2
1 is formed in the same shape as the outer shape of both when fixed. That is, the collet-like jig 21 includes a collet 2 having a tapered surface 21a that comes into contact with the tapered hole 3a of the collet holder 3 and a tapered seat 21b on which the rubber bush 5 is placed.
And a through hole 21 into which the pipe electrode 7 is inserted.
h and a protruding pipe 21 c inserted into the rubber bush 5 by a predetermined distance are formed in the same manner as the insertion jig 11. The lower end surface of the collet-like jig 21 has a through hole 2
A tapered surface 21e is formed at the insertion opening of the 1h pipe electrode. Further, a process corresponding to the step portion 11 and the tapered surface 11d of the insertion jig 11 is applied to the tip of the protruding pipe 21c. Note that the collet-like jig 21 does not require a tightening function as a collet, and thus has no slit. Further, since a portion corresponding to the large-diameter step portion 11b of the insertion jig 11 is not necessary, it may be omitted.

By mounting such a collet-like jig 21 instead of the collet 2 and the insertion jig 11, the above-described functions and effects can be applied as they are.

[0022]

As described above, according to the present invention, by inserting the insertion jig into the collet and the rubber bush,
Alternatively, by mounting a collet-like jig instead of the collet and the insertion jig, the pipe electrode can be easily and reliably inserted. In addition, with the interference for fixing the pipe electrode left in the rubber bush,
Since the insertion jig or the collet-like jig is inserted into the rubber bush, the pipe electrode can be securely fixed without damaging the pipe electrode, and the working fluid is surely sealed.

Further, the operation and effect of the present invention can be obtained only by adding the insertion jig of the present invention to the existing pipe electrode holding apparatus or by attaching a collet-like jig to the existing pipe electrode holding apparatus. Low cost.

[Brief description of the drawings]

FIG. 1 is an assembled sectional view showing a pipe electrode holding device on which an insertion jig is mounted.

FIG. 2 is a sectional view showing a vertical section of the insertion jig.

FIG. 3 is a sectional view showing another longitudinal section of the insertion jig.

FIG. 4 is a schematic diagram illustrating a fixed state and a liquid-sealed state of a pipe electrode.

FIG. 5 is an assembled sectional view showing a pipe electrode holding device on which a collet-like jig is mounted.

FIG. 6 is an assembled sectional view showing a conventional pipe electrode holding device.

[Explanation of symbols]

 Reference Signs List 1 collet chuck 2 collet 2h tool mounting hole 3 collet holder 4 collet nut 5 rubber bush 6 supply cylinder 7 pipe electrode 11 insertion jig 11b large diameter step of insertion jig 11c small diameter step of insertion jig 11d insertion Tapered surface of jig 11h Through hole of insertion jig 21 Collet-like jig 21a Tapered surface of collet-like jig 21b Tapered seat of collet-like jig 21c Projected pipe of collet-like jig 21h Through-hole of collet-like jig

Claims (3)

[Claims] 1. A pipe electrode holding device for holding a pipe electrode so as to be able to conduct electricity and supplying a processing liquid to the pipe electrode, comprising: a collet chuck including a collet; a supply cylinder for supplying a processing liquid to the pipe electrode; A pipe electrode holding device, comprising: a rubber bush disposed between the collet and the supply cylinder; and an insertion jig which is detachable from the collet and into which the pipe electrode can be inserted. 2. The insertion jig is formed to have an outer diameter such that most of its outer diameter can be inserted into a tool mounting hole of the collet and can be fixed, and one end of the jig has a larger diameter step. The other end is formed with a step portion or a tapered surface with a smaller diameter than the other end, and a through hole whose inner diameter is slightly larger than the outer diameter of the pipe electrode is formed at the center thereof, and When the jig is inserted into the rubber bush, the rubber bush is formed to have a length that allows the insertion jig to be inserted into the rubber bush, leaving a margin for fixing the pipe electrode. The pipe electrode holding device according to claim 1. 3. A pipe electrode holding device for holding a pipe electrode so as to be able to conduct electricity and supplying a working fluid to the pipe electrode, wherein the pipe electrode holding device includes a collet-like jig similar to a collet and a collet holder. And a supply cylinder for supplying a processing liquid to the pipe electrode, a collet-like jig, and a rubber bush disposed between the supply cylinders, wherein the collet-like jig inserts the pipe electrode. Possible through-holes, a tapered surface that abuts the tapered hole of the collet holder, a tapered seat on which the rubber bush is placed, and a rubber bush that leaves an interference for fixing the pipe electrode. A pipe electrode holding device, comprising: a protruding pipe formed to have a length to be inserted.