JPH0418737Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an electric discharge machining electrode, and more particularly to an electric discharge machining electrode for fine workpieces, which is advantageously used to form bottomed holes or grooves.

BACKGROUND ART FIG. 1 is a cross-sectional view for explaining a prior art. The electrical discharge machining electrode 1 has a tip surface 2 perpendicular to an axis extending vertically in FIG.
The outer peripheral surface has a shape corresponding to the desired groove 4. The vicinity of the outer peripheral edge 2a of the electric discharge machining electrode 1 is worn away by the electric discharge, and the electrode 1 changes from the initial state shown by the imaginary line 5 to the rounded state shown by the solid line 6. Therefore, when such an electric discharge machining electrode 1 is used, a groove 7 is formed in the workpiece 3. In other words, the roundness of the groove bottom corners 8 and 9 becomes large, making it impossible to form the groove 4 in the desired shape. Conventionally, in order to form a single groove, machining operations are performed while replacing a plurality of electrical discharge machining electrodes. Therefore, working time becomes longer and productivity is lower.

Purpose The purpose of the present invention is to reduce the roundness R of the bottom corner of the bottomed hole or groove of the workpiece in electric discharge machining to form a bottomed hole or groove, thereby achieving high accuracy. It is an object of the present invention to provide an electric discharge machining electrode for use in fine workpieces, which can form grooves of a desired shape.

Structure of the invention The present invention is an electric discharge machining method for fine workpieces, which is characterized in that the outer periphery of the tip extending toward the workpiece protrudes toward the workpiece and has an acute-angled tapered protrusion. It is an electrode.

Embodiment FIG. 2 is a perspective view of an embodiment of the present invention.
The tip portion 11a of the electric discharge machining electrode 11 extends toward the metal workpiece 12. In the workpiece 12 , a roughly trapezoidal groove is formed by the electrical discharge machining electrode 11 . The electrical discharge machining electrode 11 includes a support portion 11b having a rectangular cross section perpendicular to the axis, and a tip portion 11a connected to the support portion 11b.
and has. Side wall 1 in the thickness direction of the tip portion 11a
3 and 14 are parallel to each other. The remaining two widthwise inclined surfaces 15 and 16 of the tip portion 11a extend toward each other toward the workpiece 12, and the tip portion 11a is formed in a generally tapered shape. An end surface 17 of the tip portion 11a lies within a plane perpendicular to the axis of the electrical discharge machining electrode 11. Projections 18 and 19 are formed on the inclined surfaces 15 and 16 and project from the outer peripheral edge 17a of the end surface 17 toward the workpiece 12. The protrusions 18 and 19 extend between the side walls 13 and 14, and are connected to the inner surfaces 18a and 18 connected to the end surface 17.
9a and an outer surface 18 connected to the inclined surfaces 15 and 16.
b, 19b, respectively. The inner surface 18a and the outer surface 18b intersect at an acute angle. Also, the inner surface 19a
and the outer surface 19b also intersect at an acute angle. Side walls 13, 14
The distance l1 between them is selected to be larger than the width l2 of the workpiece 12 in which the groove is to be formed. That is, during electrical discharge machining, the side walls 13 and 14 of the electrical discharge machining electrode 11
is located above and outside of the workpiece 12. The electrical discharge machining electrode 11 is placed facing the position of the workpiece 12 where the groove is to be formed.

In this way, the protrusions 18 and 19 are formed into a tapered shape. These protrusions 18 and 19 are made by directly using the burrs generated when machining the sloped parts of the outer surfaces 18b and 19b during the manufacture of the discharge electrode, and thereby forming the bottom corners in the bottomed holes or grooves. This enables high-precision finishing. Therefore, in such a discharge electrode, the protrusions 18 and 19 are not added by separate machining, but are formed at the time of manufacturing the discharge electrode.

When using burrs as they are as such protrusions 18 and 19, as shown in FIG. As a result, the inclined surface 16 of the tip portion 11a is formed, and at the same time, the projection 19 shown in the second figure is formed as a burr. This also applies to the other protrusion 18. Width W1 of the tip 11a
is extremely thin, for example about 0.05 mm, so the protrusions 18, 18,
19, and the protrusion 18, which is such a burr,
Electrical discharge machining can be performed with high precision using No. 19.

FIG. 3 is a cross-sectional view showing the shape of the groove 20 when the workpiece 12 is subjected to electrical discharge machining with the electrical discharge machining electrode 11. By using the electrical discharge machining electrode 11, it is possible to form a groove 24 of a desired shape in the workpiece 12, as shown in phantom lines, as described below. Immediately after the start of electrical discharge machining, as shown in FIG.
The bottom corners 21 and 22 of the groove 20 are machined deeper than the bottom surface 23. As the machining process progresses, the protrusions 18 and 19 become smaller due to wear due to electrical discharge, as shown in FIG.
The difference in level between the bottom corners 21 and 22 of 0 and the bottom surface 23 is also reduced. Then, at the end of machining, Fig. 3
As shown in FIG.
The bottom corners 21 and 22 of 0 are finished with high precision with a very small roundness R, and the desired groove shape is obtained.

FIG. 4 is a perspective view of the vicinity of the tip of the electrical discharge machining electrode 26 according to another embodiment of the present invention. What should be noted is that the axis-perpendicular cross section of the tip 27 of the electrical discharge machining electrode 26 is square or rectangular, and the protrusions 29, 3
It is uniform in the axial direction up to the end face 28 having a zero.

FIG. 5 is a side view of the vicinity of the tip of the electrical discharge machining electrode 31 according to still another embodiment of the present invention, and FIG. 6 is a bottom view of the electrical discharge machining electrode 31. What should be noted is that the axis-perpendicular cross section of the tip 32 of the electrical discharge machining electrode 31 is circular, and the circular end surface 33 is shaped like a protrusion 34.
is provided around the entire circumference of the outer peripheral edge 33a. By using this electrical discharge machining electrode 31, a highly accurate bottom corner can be obtained even when machining a hole with a bottom. The electric discharge machining electrode having protrusions all around the outer periphery of the end face of the tip includes electric discharge machining electrodes in which the cross section of the tip at right angles to the axis and/or the end face is triangular, rectangular, or polygonal.

The protrusions 29, 30, 34 in the embodiment shown in FIGS. 4 to 6 are also connected to the electrodes 26,
During the grinding process of 31, it can be formed as a burr. In the present invention, by using the protrusions 18, 19, 29, 30, and 34, which are such burrs, it is possible to finish a highly accurate bottom corner by performing electrical discharge machining with high accuracy.

The experimental results of the present inventor will be described with reference to FIG. In the embodiments shown in FIGS. 1 to 3,
When the width W1 between the protrusions 18 and 19 is 0.05 mm, the height of the protrusions 18 and 19 is 0.01 mm, and the width of the base end of each protrusion 18 and 19 is 0.003 mm,
Groove 20 is formed by electrical discharge machining, and its depth is 0.07
mm, the width of the bottom surface 23 is 0.10 mm, and the width of the upper end of the groove 20 is 0.015 mm.
22 was confirmed to have been formed.

On the other hand, as a comparative example, protrusion 1 which is a burr
When using an electrical discharge machining electrode having a structure in which no grooves 8 and 19 are formed, the R of the bottom corners 21 and 22 is 0.035.
It was warm in mm. The results of this experiment are as described in connection with FIG. In this way, the protrusion 18,
When 19 was not present, only low precision bottom corners could be formed. As another comparative example, an electrode 45 for electric discharge machining shown in FIG. 9 having a structure similar to the electrode for electric discharge machining disclosed in Japanese Patent Publication No. 41-2520 was manufactured and subjected to electric discharge machining. Since it was impossible to manufacture a configuration in which the distance between the protrusions 46 and 47 was set to 0.05 mm as in the embodiment of the present invention, the size was increased 10 times, that is, the width was changed to as shown in FIG. 0.5mm and protrusion 46,4
The height of 7 is 0.2 mm, and the width of one protrusion 46 is 0.2 mm.
mm, and the width of the other protrusion 47 was 0.15 mm, and when the groove was formed by electric discharge machining using the electric discharge machining electrode 45 having such a structure, the bottom corners 21 and 22 of the groove in the above-mentioned embodiment were formed. The radius of the bottom corner corresponding to this was 0.03 mm, making it impossible to form a bottom corner with a small roundness. The present invention has a particularly advantageous structure in that a particularly fine groove is formed by electric discharge machining, and the R of the bottom corner of the groove is made small to achieve high precision.

Workpiece 12 having the groove 20 thus obtained
can be used, for example, as a cutter blade for cutting ultra-fine wire, which is the wire of a servo motor coil. The blade, which is the workpiece 12, is moved close to the ultra-fine wire provided on the fixed blade, and the ultra-fine wire is held in line contact with the bottom 23 of the groove 20 and the slopes on both sides of the groove 23. It is cut between the fixed blade and the fixed blade. In order to allow the groove 20 to bring the ultrafine wire into line contact and hold the wire in a stable state for cutting, it is necessary to reduce the radius R of the bottom corner. The present invention can be implemented not only for manufacturing such cutter blades, but also for electrical discharge machining of other fine workpieces. Protrusion 1
8, 19, it is possible to utilize burrs as described above.

Effects As described above, according to the present invention, in electrical discharge machining to form a bottomed hole or groove, etc., the bottom corner of the bottomed hole or groove of the workpiece can be finished with high precision using the electrical discharge machining electrode. Holes or grooves of desired shape can be formed. In particular, according to the present invention, the protrusion is
The protrusion protrudes toward the workpiece and has a tapered shape, and burrs generated during the manufacture of the discharge electrode can be used as they are for such a protrusion. Therefore, productivity is excellent. Moreover, according to the electrode of the present invention, it is possible to finish the bottom corner of a bottomed hole or groove with high precision.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the vicinity of the tip of a conventional electrical discharge machining electrode 1, FIG. 2 is a perspective view showing the vicinity of the tip of the electrical discharge machining electrode 11 and a workpiece 12 according to an embodiment of the present invention, and FIG. The figure shows a workpiece 12 with an electric discharge machining electrode 11.
FIG. 4 is a perspective view of the vicinity of the tip of the electrical discharge machining electrode 26 according to another embodiment of the present invention, and FIG. 5 is a cross-sectional view showing the shape of the groove 20 during electrical discharge machining. FIG. 6 is a bottom view of the electrical discharge machining electrode 31, and FIG. 7 is a grinding operation when forming burrs, which are the protrusions 18 and 19 of the present invention. FIG. 8 is a simplified perspective view showing the experimental results of the present inventor, and FIG. 9 is a perspective view of an electric discharge machining electrode 45 shown as a comparative example. 1, 11, 26, 31... electrical discharge machining electrode, 3,
12... Workpiece, 2a, 17a, 33a... Outer periphery, 11a, 27, 32... Tip, 18, 1
9, 29, 30, 34...Protrusion.

Claims (1)

[Scope of utility model registration request] 1. An electrical discharge machining electrode for fine workpieces, characterized in that the outer peripheral edge of the tip extending toward the workpiece projects toward the workpiece and has an acute-angled tapered protrusion.