JPH0976123A - Electric discharge tool electrode and electric discharge machine using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably discharge work chips even if the working speed is high, so as to prevent abnormal electric discharge, by forming a discharging passage extending from the electric discharge end side to the opposite side. SOLUTION: Two spiral grooves 13c, 13d extending from the electric discharge end side to the opposite side are formed on the outer periphery of a tool electrode 13. The grooves 13c, 13d function as discharging passages for discharging work chips. Fine metallic powder as work chips generated in the electric discharge working process are discharged by pressure generated with the electric discharge. That is, since the spiral grooves 13c, 13d are formed on the tool electrode 13 from the electric discharge end side to the opposite side, the metallic powder generated near the electric discharge part is smoothly and quickly discharged upward by the pressure of electric discharge through the grooves 13c, 13d in a state where it is mixed with insulating liquid 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining tool electrode and an electric discharge machine using the tool electrode, and more particularly to a machine suitable for machining fine holes.

[0002]

2. Description of the Related Art FIG. 6 shows a state in which machining is performed by a conventional electric discharge machine. As shown, an electric discharge machining tool electrode (hereinafter simply referred to as a tool electrode) 101
And the workpiece 102 as electrodes, and the tool electrode 101 is gradually lowered while repeatedly performing spark discharge 104 between the tip end of the tool electrode 101 and the workpiece 102 in the insulating liquid 103, A hole 105 is formed by removing a small amount of the workpiece 102 by electric discharge.

In the above-mentioned electric discharge machining, fine metal powder 107, which is a scrap, is generated. In order to finish the hole 105 with high precision, this metal powder is provided between the outer circumference of the tool electrode 101 and the inner circumference of the hole 105. It is indispensable to discharge 107 quickly without accumulating.

Since the metal powder 107 is a conductor, if it collects, the abnormal discharge 1 on the side of the tool electrode 101 will occur.
09 is likely to occur, and there is a risk that an infinite number of grooves 110 may be formed on the inner peripheral surface of the already formed hole 105 due to abnormal discharge.

Usually, the discharge of the metal powder 107 is performed by the pressure associated with the normal spark discharge 104, and further, the artificially pressurized insulating liquid is injected to forcibly remove it.

[0006]

However, the finer the hole to be machined, the more difficult it becomes to efficiently discharge the metal powder 107, and in order to reliably discharge the metal powder 107, it is necessary to slow down the processing speed. At present, there is no choice but to take effective measures, and this is a problem that should be solved in order to improve production efficiency.

The present invention has been made in view of the above-mentioned drawbacks of the prior art. An object of the present invention is to reliably discharge the machining waste even if the machining speed is large and prevent the occurrence of abnormal discharge, thereby improving the efficiency. It is an object of the present invention to provide an electric discharge machining tool electrode and an electric discharge machining machine that make it possible to perform fine machining.

[0008]

[Means for Solving the Problems] To achieve the above object,
The electric discharge machining tool electrode according to the present invention has a discharge path extending from the discharge end side to the opposite side.

To achieve the same object, an electric discharge machine according to the present invention comprises a tool electrode and a tool driving means for holding the tool electrode and moving the tool electrode at least in a contacting / separating direction with respect to a workpiece. The tool electrode has a discharge path extending from the discharge end side to the opposite side.

In the electric discharge machining tool electrode and the electric discharge machine having the above construction, the machining waste is pressurized by the pressure generated by the normal electric discharge generated between the tip of the tool electrode and the workpiece, and is smoothly discharged through the discharge passage. Is discharged to.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is carried out in order to discharge machining waste without delaying, while maintaining a high machining speed when a hole having a very small diameter is formed by electric discharge machining.

[0012]

Next, an electric discharge machine (including an electric discharge tool electrode according to the present invention) as an embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, the electric discharge machine is equipped with a machining tank (not shown), in which an insulating liquid 1 such as white kerosene is stored, and a mounting base 2 is provided at the bottom. . The processing tank is further mounted on a movable table (not shown) that is driven in the front-rear direction (indicated by arrow Y) and in the left-right direction (direction perpendicular to the plane of the drawing), and is moved to an appropriate position by operating the movable table. Moved and positioned.

On the other hand, the column of the electric discharge machine (colu
An electrode head 7 is movably attached to the mn) 5 in the up-down direction (indicated by arrow Z) and is moved up and down by a head driving means (not shown). A rotary table unit 9 as a rotating means is attached to the electrode head 7. The rotary table unit 9 has a unit main body 9a containing a rotary drive means (not shown) including a motor and the like, and a rotary table 9b rotated by the rotary drive means.

A chuck 11 is attached to the rotary table 9b, and an electric discharge machining tool electrode (hereinafter, simply referred to as a tool electrode) 13 is detachably attached to the chuck 11.

The above-mentioned electrode head 7 and the electrode head 7
The head driving means for moving up and down, the rotary table unit 9, the chuck 11 and the like constitute a tool driving means for moving the tool electrode 13. In this embodiment, the tool driving means causes the tool electrode 13 to perform a contacting / separating operation and a rotating operation with respect to a workpiece (described later).

In the case of this embodiment, the tool electrode 13 is formed in a substantially columnar shape, and the material thereof is brass, copper, carbon, silver-tungsten sintered material or the like depending on the purpose of processing. As is apparent from FIG. 2, the discharge end of the tool electrode 13 is sharpened in a conical shape with an angle of θ, for example, about 120 °. The discharge end face of the tool electrode 13 is shown in FIG.
Also, in FIG. 2, reference numeral 13a is used.

On the outer peripheral portion of the tool electrode 13, there are two spiral grooves 13c and 13 extending from the discharge end side to the opposite side.
d is formed. The grooves 13c and 13d act as a discharge path for discharging machining waste and the like.

As shown in FIG. 2, the outer peripheral surface of the tool electrode 13 (including the inner surfaces of the spiral grooves 13c and 13d) is coated with an insulating material 15 such as Teflon.

Next, the processing status of the electric discharge machine will be described.

As shown in FIG. 1, the work piece 17 is placed and fixed on the mount 2 by an operator. However, the workpiece 17 is completely immersed in the insulating liquid 1. In this state, a processing tank (not shown) accommodating the mounting base 2 and the insulating liquid 1 is appropriately moved in a horizontal plane, and the portion of the workpiece 17 to be processed is positioned directly below the tool electrode 13. It

The movement of the processing tank is performed by moving a movable table (not shown) equipped with the processing tank by an operator's operation.

After the positioning of the processed portion of the work piece 12 is completed, the operator lowers the electrode head 7 to an appropriate position to bring the tool electrode 13 into close proximity to the work piece 12.
Then, the processing start switch is turned on.

Then, the head driving means (not shown) is actuated, the electrode head 7 starts descending (feeding) at a predetermined speed, and the rotary table unit 9 starts rotating (indicated by an arrow R). At the same time, A required pulse voltage is applied to the tool electrode 13 and the workpiece 17.

As described above, the tool electrode 13 descends while rotating (indicated by the arrow R), and the feed (lowering) control by the head driving means is performed so as to keep the electrode gap, that is, the discharge gap constant.

Therefore, as shown in FIGS. 3 and 4, spark discharge 20 is repeatedly performed between the discharge end surface 13a of the tool electrode 13 and the workpiece 17, and the workpiece 20 is discharged by this discharge 20.
The surface of 7 is removed in minute amounts to form holes 22.

In the above-mentioned electric discharge machining step, fine metal powder 24 (shown in FIG. 4), which is machining scrap, is generated. The metal powder 24 is discharged by the pressure associated with the discharge 20. That is, the tool electrode 13 has a spiral groove 13c,
Since 13d is formed from the discharge end side to the opposite side, the metal powder 24 generated in the vicinity of the discharge portion is mixed with the insulating liquid 1 by the pressure of the discharge, so that the grooves 13c, 13
It is smoothly and promptly discharged upward (indicated by arrows A and B in FIG. 4) through d.

The metal powder 24 is also discharged from the gap between the outer peripheral surface of the tool electrode 13 and the inner peripheral surface of the hole 22.

In this embodiment, the tool electrode 13 and the hole 2
Although the gap between the inner surface of No. 2 and the inner surface is shown to be extremely large, this is for clarifying the configuration, action, etc., and is actually about 0.02 (mm), for example.

As described above, in the electric discharge machine, the metal powder 24 serves not only as a gap between the outer peripheral surface of the tool electrode 13 and the inner peripheral surface of the hole 22 but also as a discharge path formed in the tool electrode 13. It is smoothly discharged through the grooves 13c and 13d. Therefore, even if the machining speed is set to a high value, the metal powder 24 does not become stagnant, abnormal discharge due to the metal powder is prevented, and the processing of the fine holes 22 can be performed efficiently.

By the way, in the electric discharge machine, the rotary table unit 9 shown in FIG.
Is being rotated by the rotary table unit 9 to perform electric discharge machining. Because of this structure, the metal powder 2
4 is a spiral groove 13c, 1 formed in the tool electrode 13
Rather than rising only along with the action of pressure along 3d, the discharge is promoted by the upward thrust generated due to the spiral shape of the grooves 13c and 13d and this rotation.

It should be noted that the above-described rotation operation of the tool electrode 13 is not always performed, and the effect of discharging the metal powder can be sufficiently satisfied without rotation. Therefore, the electric discharge machining may be performed only by lowering the electrode head 7 without providing the rotary table unit 9.

Now, in the electric discharge machine, the following operation is performed during the machining of the hole 22.

That is, the electrode head 7 shown in FIG. 1 is operated, and as shown in FIGS.
3 is reciprocated once or several times (indicated by arrows U and D) in the up-and-down direction, which is the direction of approaching and separating from the workpiece 17. Thereby, the metal powder 24 is discharged more efficiently. That is, as shown in FIG. 5A, when the tool electrode 13 is pulled up from the inside of the hole 22, the insulating liquid 1 around the tool flows into the hole 22 (indicated by an arrow I). Then, as shown in FIG. 5B, the tool electrode 13 is again inserted into the hole 22.
When it is inserted into the hole 22, the pressure inside the hole 22 increases and the insulating liquid in the hole vigorously jumps out from the gap between the tool electrode 13 and the inner peripheral surface of the hole (indicated by the arrow O), and together with the insulating liquid, the metal powder 2
4 is discharged.

In the present embodiment, the tool electrode 13
Has a substantially columnar shape, but various types of tool electrodes are adopted depending on the shape of a hole or the like to be processed in the workpiece.

Further, in this embodiment, the tool electrode 13
The discharge passage provided in the
Although they are c and 13d, they may be grooves that extend straight in the axial direction of the tool electrode 13, or may be pores formed so as to penetrate the axial center of the tool electrode. However, forming a groove in the outer peripheral portion is particularly effective for a minute tool electrode.
This is easier than forming a hole inside.

Further, since the grooves 13c and 13d are formed in a spiral shape, it is difficult for the metal powder 24 which has once risen to fall again.

Further, as described above, the tool electrode 13 is
An insulating material 15 (shown in FIG. 2) is coated on the outer peripheral surface thereof. With this configuration, abnormal discharge is less likely to occur between the outer peripheral portion of the tool electrode and the inner peripheral surface of the hole.

In addition, although the present invention is effective for processing a small diameter hole, even when forming a relatively large hole,
It is also useful when machining other than holes.

[0040]

As described above, according to the present invention,
The machining waste is smoothly discharged not only through the gap between the outer peripheral surface of the tool electrode and the inner peripheral surface of the hole, but also through the discharge passage formed in the tool electrode. Therefore, even if the processing speed is set to a high value, the processing waste is not delayed, abnormal discharge is prevented, and fine processing can be efficiently performed.

[Brief description of drawings]

FIG. 1 is a front view of a main part of an electric discharge machine according to the present invention including a partial cross section.

2 is a vertical cross-sectional view of a part of a tool electrode used in the electric discharge machine shown in FIG.

FIG. 3 is an operation explanatory view showing a machining situation by the electric discharge machine shown in FIG. 1.

4 is an operation explanatory view showing a machining situation by the electric discharge machine shown in FIG.

5 is an operation explanatory view showing a machining situation by the electric discharge machine shown in FIG. 1;

FIG. 6 is an operation explanatory view showing a situation where machining is performed by a conventional electric discharge machine.

[Explanation of symbols]

1 Insulating Liquid 2 Mounting Base 5 Column 7 Electrode Head 9 Rotating Table Unit 11 Chuck 13 (Electric Discharge Machining) Tool Electrodes 13c, 13d (of Tool Electrode 13) (spiral) Groove (Discharge Path) 15 Insulation Material 17 Workpiece 20 Spark discharge 22 Hole 24 Metal powder (processing waste)

Claims (7)

[Claims] 1. An electric discharge machining tool electrode, characterized in that a discharge path from the discharge end side to the opposite side is formed. 2. The electric discharge machining tool electrode according to claim 1, wherein the discharge path is a groove formed on an outer peripheral portion of the tool. 3. The electric discharge machining tool electrode according to claim 2, wherein the groove has a spiral shape. 4. The electric discharge machining tool electrode according to claim 1, wherein the outer peripheral surface of the tool is coated with an insulating material. 5. A tool electrode is provided, and tool driving means for holding the tool electrode and moving the tool electrode in at least a contacting / separating direction with respect to a workpiece. The tool electrode is provided from the discharge end side to the opposite side. An electric discharge machine characterized in that a discharge path extending therethrough is formed. 6. The electric discharge machine according to claim 5, wherein the tool driving means discharges the machining waste together with the insulating liquid by reciprocally moving the tool electrode in the contact and separation directions. 7. The discharge path is a spiral groove formed on the outer peripheral portion of the tool, and the tool driving means has a rotating means for rotating the tool electrode.
Alternatively, the electric discharge machine according to claim 6.