JPH0746424Y2 - Jet nozzle for wire electric discharge machine - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is for a wire electric discharge machine in a wire electric discharge machine for electric discharge machining a workpiece with electric discharge energy generated between a traveling wire electrode and the workpiece. Regarding a jet nozzle.

[Conventional technology]

Conventionally, the wire electric discharge machine guides the wire electrode by various rollers and supplies it to the upper wire head, and the table on which the workpiece is mounted is commanded from the NC device in the X and Y directions according to the machining shape of the workpiece. It moves to generate an electrical discharge between the workpiece and the wire electrode, and the electrical discharge machining is performed on the workpiece by the discharge energy.

The wire electrode and the table repeat servo movements during machining, so not only do they move relatively in the machining direction during wire electrical discharge machining, but if electrical discharge machining becomes unstable depending on the situation such as machining chips, a short circuit will be resolved. Therefore, for a moment, it also retreats along the machining trajectory, and then advances again to perform electric discharge machining. The wire electric discharge machine receives a command from the NC device,
The workpiece moves in the horizontal direction, that is, the X direction and the Y direction, the movements of the two are combined, and the relative movement of the two causes electric discharge machining of a predetermined machining shape on the workpiece.

Generally, the machining fluid supply device in the wire electric discharge machine is
The machining fluid is jetted to the electric discharge machining portion of the workpiece from a jet nozzle installed in the vertical direction with respect to the electric discharge machining portion and the wire electrode. As a machining fluid supply device in a wire electric discharge machine, for example, there are those disclosed in Japanese Utility Model Publication No. 61-178627, Japanese Utility Model Publication No. 61-178628, Japanese Utility Model Publication No. 61-195927, and the like.

In general, the wire diameter of the wire electrode used in the wire electric discharge machine is as small as φ0.03 to φ0.35, spark discharge occurs during machining, and when the wire electrode is exposed to the air,
The wire breaks instantly. Therefore, the wire electrode is always arranged in the machining fluid during electric discharge machining.

Normally, the wire electrode is caused to travel to the center of the liquid column ejected from the jet nozzle by the working liquid pressure applied to the jet nozzle, and a voltage between electrodes is applied between the wire electrode and the workpiece to cause discharge, and the discharge Energy is used to wire-discharge machine a workpiece. Or, with some types of wire EDM,
There is also one in which wire electric discharge machining is performed by causing an electric discharge between a workpiece and a wire electrode while the workpiece is submerged in the machining liquid.

Recently, as the machining speed of the wire electric discharge machine has increased, the machining fluid pressure supplied to the jet nozzle has also increased, and the gap between the end face of the jet nozzle and the machining surface of the workpiece is maintained at a very small gap. It's starting to happen. Further, regarding the lower wire head in the wire electric discharge machine, the guide holder to which the jet nozzle is attached is provided at the tip of the arm extending from the machine body. In other words, there is a guide holder at the tip of the cantilever arm, and the jet nozzle is attached to the guide holder.

[Problems to be solved by the device]

Generally, in the case where the conventional machining fluid is jetted from the upper and lower jet nozzles to the wire electrode and the electric discharge machining part of the workpiece, the machining fluid is evenly distributed to the electric discharge machining part of the workpiece and the wire electrode. When the non-applied state occurs, or when air is present at the electric discharge machining site, a phenomenon occurs in which the wire of the wire electrode is broken due to air discharge.

The machining fluid supplied from the jet nozzle for machining fluid supply is a transparent water column containing no air when the fluid pressure is low, but the jet stream of machining fluid increases as the machining speed of electrical discharge machining increases. When the pressure is increased, a negative pressure is generated between the jet nozzle and the workpiece, and air is sucked from the surroundings or is entrained by an external force. Occurs, that is, it becomes a milky white water column,
When the machining fluid in such a state is jetted to the electric discharge machining part of the workpiece and the wire electrode, the above-mentioned air discharge is caused, which causes the wire of the wire electrode to be broken.

At the time of electrical discharge machining, high pressure liquid is supplied,
The jet nozzle must withstand it. Typically,
The through holes of the jet nozzle, that is, the jet holes are set to about φ5 to φ10, and accordingly, the outer diameter of the jet nozzle is formed to about φ13 to φ15. That is, the jet nozzle is configured to have a strength capable of withstanding the hydraulic pressure of the machining fluid supplied during electric discharge machining.

On the other hand, the gap between the end surface of the jet nozzle, that is, the discharge side of the machining liquid and the machining surface of the workpiece is set to a minute gap in order to maintain stable machining conditions. As described above, when the jet nozzle having a certain degree of mechanical strength is brought close to the workpiece at a high moving speed, when the workpiece is attached to the machining table for machining, the preparatory work for machining is performed. If a jet nozzle collides with a clamp that holds the workpiece during electrical discharge machining, such as a clamp or metal fitting, due to a mishandling by a worker, etc. A phenomenon in which the accuracy of a certain guide holder decreases may occur.

In particular, since the wire electric discharge machine requires high-precision machining, it is necessary to pay close attention to the lower surface of the workpiece, in other words, the verticality of the upper surface of the machining table and the axial direction of the wire electrode. When a collision accident occurs in the guide holder that supports the guide holder, it is necessary to restore the setting accuracy of the guide holder and spend a great deal of time and labor for the restoration operation.

On the other hand, for example, if the jet nozzle is made of an elastic material such as vinyl chloride resin, accuracy deterioration due to impact such as collision can be reduced, but due to the working fluid pressure supplied at high pressure, the jet nozzle has a jet hole. Is deformed, and as a result, a turbulent flow is generated in the discharged liquid, the laminar flow shape is broken in the supply of the working liquid, and it becomes impossible to secure the processing accuracy for the processed shape of the workpiece.

The purpose of this device is to solve the above problems,
In a wire electric discharge machine that ejects machining fluid to the electric discharge machining part of the wire electrode and the work piece to generate electric discharge between the work piece and the wire electrode, and to perform electric discharge machining of the work piece by the discharge energy. The ejection shape is jetted in a laminar shape to secure the strength of the jet nozzle body and prevent the guide holder supporting the jet nozzle body from being impacted by an unexpected collision and lowering the accuracy of the guide holder. It is an object of the present invention to provide a jet nozzle for a wire electric discharge machine, which can secure machining accuracy for a machining shape of a workpiece.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the present invention is directed to a jet nozzle having a jet hole which is disposed so as to generate an electric discharge between a traveling wire electrode and a workpiece to face a workpiece to be electric discharge machined and which jets a machining liquid to an electric discharge machining site. And a wire electric discharge machine having a guide holder in which the jet nozzle is held by a nozzle holder, the jet nozzle is detachably fixed to the guide holder with the nozzle holder, and the jet projecting to the outside of the nozzle holder The present invention relates to a jet nozzle for a wire electric discharge machine, characterized in that a notched groove forming a thin portion that is sheared and broken by an excessive external force is formed on an outer peripheral surface of a tip portion of the nozzle.

[Action]

The jet nozzle for the wire electric discharge machine according to the present invention is configured as described above and operates as follows. That is,
In this jet nozzle for a wire electric discharge machine, the jet nozzle is detachably fixed to a guide holder with a nozzle holder, and the outer peripheral surface of the tip portion of the jet nozzle protruding to the outside of the nozzle holder is sheared and broken by an excessive external force. Since the notch groove forming the thin wall portion is formed, the portion of the notch groove is thin and weak in strength as compared with other portions. Therefore, the jet nozzle is fixed to the guide holder for accuracy, but when the jet nozzle receives an excessive external force such as an unexpected impact, the cutout groove portion is cut by the shear pin function. It is possible to minimize the influence of external force on the guide holder that supports the jet nozzle, because the jet nozzle main body at the tip portion where the groove is formed is broken due to shear fracture.

〔Example〕

Hereinafter, embodiments of the jet nozzle for a wire electric discharge machine according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing a partially broken surface showing an embodiment of a jet nozzle for a wire electric discharge machine according to the present invention, and FIG. 2 is a plan view of FIG.

In the wire electric discharge machine, the workpiece 2 is attached to the workpiece mount.
Is installed. The workpiece mount can be moved horizontally by servo movement, that is, in the X and Y directions. That is, workpiece 2
The workpiece mounting table to which is attached moves in the X and Y directions according to the machining shape of the workpiece 2 in response to a command from the NC device, so that machining can proceed with the wire electrode 1 supplied to the electric discharge machining site. Is configured. The upper and lower wire heads provided for the workpiece 2 are a power feeding member, a power feeding pressing member,
A die guide member, a machining fluid injection nozzle, etc. are provided respectively.

The wire electrode 1 sent from an automatic wire feeder (not shown) through a roller guide, a tension roller, etc. (not shown) passes through the power supply in the upper wire head, the die guide member, the jet nozzle, etc. A voltage between the electrodes is applied between the wire electrode 1 and the workpiece 2 at the electrical discharge machining site between the heads to cause electrical discharge, and the workpiece 2 is subjected to electrical discharge machining. Then, the wire electrode 1 becomes the used wire electrode 1, and the jet nozzle 3 in the lower wire head, the power supply,
It is pulled out by a wire pulling device through a die guide member and the like, and is discharged to a take-up reel, a used wire pool portion and the like (not shown).

1 and 2 show an example of a main part of a mounting structure for mounting the jet nozzle according to the present invention to a wire electric discharge machine. Here, an example of a lower wire head is shown. 2 shows a jet nozzle 3 arranged below 2 and a guide holder 5 constituting a lower wire head.

An electric power supply, a die guide and the like are arranged in the hollow portion 11 of the guide holder 5, but these are not the essential parts of the present invention, and therefore, illustration and description thereof are omitted here.

The mounting structure of the jet nozzle 3 is mainly composed of an arm 6 fixed to the apparatus main body, a guide holder 5 fixed to the arm 6 by a set bolt 7, and an upper end surface 16 of the guide holder 5 and a lower end surface 17 of the jet nozzle 3. It is composed of a nozzle holder 4 that presses into contact. The nozzle holder 4 is
It is composed of a cap nut having an internal thread 13, and has a flange portion 14 extending inward in the radial direction at the upper end thereof.

When the jet nozzle 3 is attached to the guide holder 5 with the nozzle holder 4 and fixed in a removable manner, the lower end surface 17 of the jet nozzle 3 is placed in contact with the upper end surface 16 of the guide holder 5,
The female screw 13 of the nozzle holder 4 is screwed into the male screw 12 formed on the upper portion of the guide holder 5, and the flange portion 14 of the nozzle holder 4 is brought into contact with the step portion 15 formed on the outer peripheral portion of the jet nozzle 3 This can be achieved by fastening the holder 4 to the guide holder 5.

In this case, in order to prevent the working fluid from leaking through the threaded portions of the nozzle holder 4 and the guide holder 5, the nozzle holder 4
The O-ring 8 is arranged between the guide holder 5 and the guide holder 5 for sealing.

An example of fixing the arm 6 and the guide holder 5 will be described. The mounting portion 25 of the guide holder 5 is formed with an elongated hole 22 extending in the vertical direction. The side surface of the mounting portion of the guide holder 5 is brought into contact with the side surface of the arm 6, and the set bolt 7 is inserted into the elongated hole 22 of the guide holder 5 with the washer 23 interposed.
The set bolt 7 is screwed into the female screw 24 of the arm 6. Next, the guide holder 5 is adjusted in the vertical direction with respect to the arm 6 to set it at a predetermined position, and the set bolt 7 is moved to the arm 6
Tighten the female screw 24 of to fix. In this case, the position of the guide holder 5 is set, for example, between the lower surface of the workpiece 2 and the upper end surface 21 of the jet nozzle 3 fixed to the guide holder 5.
Positioning is performed so that a predetermined gap, that is, a predetermined gap L is formed.

This jet nozzle for a wire electric discharge machine is particularly characterized by the outer shape of the jet nozzle 3. The jet nozzle 3 has a jet hole 10 formed in the center thereof through which the wire electrode 1 travels. The machining fluid is ejected from the jet hole 10 as a liquid column,
The wire electrode 1 extends to the center of the jet hole 10 so as to run in the center of the liquid column in order to avoid air discharge.

The jet nozzle 3 is formed with an annular notch groove 9 on the outer peripheral surface thereof and has a wall thickness or a thin wall. The cutout groove 9 of the jet nozzle 3 is exposed to the outside of the guide holder 5 and the nozzle holder 4 when the jet hole 10 is fixed to the guide holder 5 so as to face the workpiece 2. The nozzle holder 4 is positioned so as to project outward from the upper end surface 26.

The cutout groove 9 formed in the jet nozzle 3 is
The shape is not limited as long as it is formed so that the shearing force becomes small at any part in the longitudinal direction.

Further, as for the material for manufacturing the jet nozzle 3, as long as the material has mechanical strength to some extent, does not cause rust or corrosion with respect to a working fluid such as water, and has an electrically insulating property. It's good. Further, depending on the purpose of wire electric discharge machining, the jet nozzle is used by replacing it with another one and is also a consumable item. Therefore, it is preferable to use a material that is easily available, inexpensive, and has good machining characteristics, for example, a synthetic resin such as an acetal resin.

In FIG. 1, a notch groove 9 formed in the jet nozzle 3
An example of the shape of is shown. The cutout groove 9 is composed of a flat surface 18 extending outward in the radial direction perpendicularly, a cylindrical outer surface 19 and a tapered surface 20 extending in the radial upward direction. By forming the notch groove 9 in such a shape, for example, when an unexpected collision accident occurs in the jet nozzle 3 and the jet nozzle 3 is broken by the impact force at the portion of the notch groove 9, The influence of breakage of the jet nozzle 3 on the holder 5 is minimized.

The shape of the notch groove 9 formed on the outer peripheral surface of the jet nozzle 3 is
The shape is not limited to that shown in FIG. 1, and may be configured, for example, in the shape shown in FIG. 3, FIG. 4 or FIG. In FIG.
An annular notch 9A having a V-shaped cross section is formed on the outer peripheral surface of the jet nozzle 3. Or, in FIG. 4,
An annular notch 9B having a U-shaped cross section is formed on the outer peripheral surface of the jet nozzle 3. Alternatively, in FIG. 5, an annular cutout groove 9C having a square cross section is formed on the outer peripheral surface of the jet nozzle 3.

[Effect of device]

The jet nozzle for a wire electric discharge machine according to the present invention is configured as described above and has the following effects. That is, in this jet nozzle for a wire electric discharge machine, the jet nozzle is detachably fixed to the guide holder by the nozzle holder for accuracy reasons, but the tip end portion of the jet nozzle protruding to the outside of the nozzle holder is fixed. Since a notch groove that constitutes a thin wall portion that is sheared and broken by excessive external force is formed on the outer peripheral surface of the nozzle, the outer peripheral surface of the tip of the jet nozzle becomes a thin wall portion due to the notch groove. ,
The portion of the notch groove is relatively weak in strength, and the stress is concentrated.

Therefore, when the jet nozzle receives an excessive external force such as an impact due to an unexpected accident, an operator's mistake, etc., the portion of the cutout groove functions as a shear pin and stresses the portion where the cutout groove is formed. Are concentrated, which causes the jet nozzle body to break due to shear fracture, which can minimize the influence of external force on the guide holder that supports the jet nozzle, and the machining of the machining shape of the workpiece. Accuracy can be secured.

Further, when the nozzle holder is held by the guide holder so that the jet hole faces the workpiece, the notch groove is positioned so as to project from the end surface of the nozzle holder. Even if it is exposed and the jet nozzle is broken, it hardly affects the mounting state of the guide holder by the jet nozzle.

[Brief description of drawings]

FIG. 1 is a partially sectional front view showing an embodiment of a jet nozzle for a wire electric discharge machine according to the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is another view of the jet nozzle according to the present invention. 4 is a sectional view showing an embodiment of the jet nozzle according to the present invention, and FIG. 4 is a sectional view showing another embodiment of the jet nozzle according to the present invention. 1 ... Wire electrode, 2 ... Workpiece, 3 ... Jet nozzle,
4 ... Nozzle holder, 5 ... Guide holder, 9,9A, 9B, 9C
...... Notch groove, 10 …… Jet hole.

Claims (1)

[Scope of utility model registration request] 1. A jet nozzle having a jet hole arranged to face a workpiece to be electric discharge machined by generating an electric discharge between a traveling wire electrode and the workpiece, and having a jet hole for jetting a machining liquid to an electric discharge machining site. And a wire electric discharge machine having a guide holder that holds the jet nozzle by a nozzle holder, wherein the jet nozzle is detachably fixed to the guide holder by the nozzle holder, and the jet nozzle protrudes to the outside of the nozzle holder. A jet nozzle for a wire electric discharge machine, characterized in that a notched groove forming a thin portion that is sheared and broken by an excessive external force is formed on the outer peripheral surface of the tip portion of the wire electric discharge machine.