JPH0669652B2 - Electric discharge method for oblique holes - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of machining an oblique hole by electric discharge machining.

[Prior Art] When machining a through hole by electrical discharge machining, it is effective to open a pilot hole by pre-machining or the like in order to shorten the machining time (JP-A-51-85594). .

A conventional method for processing an oblique hole will be described with reference to FIGS. 2 to 5.

First, in order to make a pilot hole, a counter boring process is performed on a workpiece 1 to form a machining surface 3 perpendicular to the machining axis 2 (FIG. 2).
Next, drilling is performed to open the pilot hole 4. And
Electric discharge machining is performed with the cylindrical pipe electrode 5, and the pilot hole 4
The diagonal hole 6 parallel to is processed. (Fig. 3). At this time, the following problems occur. That is, electric discharge between the electrode 5 and the workpiece 1 occurs only on the outer peripheral surface 7 of the electrode 5, and no electric discharge occurs on the inner peripheral surface 8, which causes uneven consumption of the electrode 5. Therefore, if a large number of oblique holes are continuously subjected to electric discharge machining, the tip portion 9 of the electrode 5 becomes a pointed shape (Fig. 4), and the size or shape cannot be accurately machined as it is. As a countermeasure against this, as shown in FIG. 5, the diameter of the pilot hole 4'is made smaller than the inner diameter of the electrode 5, but the effect of shortening the electric discharge machining time by the pilot hole 4'is reduced. There is.

As described above, the conventional method has a problem that electric discharge is concentrated on a part of the electrode and causes uneven consumption of the electrode, and a problem that an extra step such as a counterbore process is required to form an oblique pilot hole. was there.

[Problems to be solved by the invention]

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electric discharge machining method for oblique holes, which can reduce uneven wear of electrodes and can continuously open a large number of oblique holes. And

[Means for solving problems]

Therefore, in the present invention, there is provided a machining method for forming an oblique hole having an angle with respect to a line perpendicular to the processed surface of the workpiece by electric discharge machining, and the oblique hole to be formed in the preliminary workpiece. When a pipe electrode for machining the oblique hole is sent out at an angle different from that, a pilot hole having an angle at which the inner peripheral surface and the peripheral side surface of the pipe electrode intersect is formed, and then the above-mentioned forming is attempted. There is provided an electric discharge machining method for an oblique hole, characterized in that the pipe electrode is fed while being rotated in the direction of the oblique hole to perform electric discharge machining.

[Action]

According to the above configuration, when the pipe electrode for processing the diagonal hole is sent out at an angle different from that of the diagonal hole to be formed by the pilot hole, the inner peripheral surface of the pipe electrode and the peripheral side surface of the pilot hole are formed. Since they are formed at an intersecting angle, not only the outer peripheral surface of the pipe electrode during electric discharge machining, but also discharge occurs between the inner peripheral surface of the pipe electrode and the peripheral side surface of the pilot hole,
Since the pipe electrode is rotating, the discharge points are dispersed without being partially concentrated.

[Action]

According to the above configuration, since the advancing direction of the electrode and the direction of the pilot hole have an angle, and the relative positional relationship between the electrode and the pilot hole changes as the electric discharge machining progresses, a part of the electrode is formed. Discharge spots are dispersed without the discharge being concentrated, and uneven consumption of the electrodes can be significantly reduced.

〔Example〕

 An embodiment of the present invention will be described with reference to FIG.

In this embodiment, first, the prepared hole 10 is drilled in a direction perpendicular to the processed surface of the workpiece 1 by drilling or the like. Since the prepared hole 10 is vertical to the processing surface, the spot boring process is not necessary. Next, while the cylindrical pipe electrode 5 is rotated, it is sent out in the direction of the oblique hole to be formed, and the oblique hole is processed by electric discharge machining. The pipe electrode 5 is sent to the position indicated by the imaginary line. At this time, the diameter of the pilot hole 10 is set so that the inner peripheral surface 8 of the pipe electrode 5 and the peripheral side surface of the pilot hole 10 intersect with each other at an elliptical line connecting the points 11 and 12 shown in the drawing. Therefore, at the beginning and the end of the electric discharge machining, that is, when machining the portion 13 near the upper end and the portion 14 near the lower end of the pilot hole 10, electric discharge is also performed on the inner peripheral surface 8 of the pipe electrode 5, so that the pipe It is possible to significantly reduce the consumption of the tip of the electrode 5 in a pointed shape.

From the geometrical conditions, the diameter D of the prepared hole 10 is as follows: the plate thickness of the workpiece 1 is 1, the inclination of the oblique hole is θ, the outer diameter of the pipe electrode 5 is d1, and the inner diameter is d2. Is.

(1) When l> (d1−d2) / 2sinθ, D <d1 / cosθ−ltanθ (2) When l <(d1−d2) / 2sinθ, D <ltanθ + d2 / cosθ Workpiece in this embodiment 1 is a stainless steel material with a plate thickness l = 1 mm, the inclination of the diagonal hole is θ = 10 °, the pipe electrode 5 is made of copper and has an outer diameter d1 = 0.76 mm and an inner diameter d2 = 0.46 mm.
The condition for the diameter D of 10 is D <0.595 mm.
Setting to 0.55 mm gave good results.

As described above, in this embodiment, since the direction of the pilot hole 10 is the direction perpendicular to the surface of the workpiece 1, the counterbore processing is not required to open the pilot hole 10, and the drilling of the pilot hole 10 is not required. It has the advantage of being extremely easy. The diameter of the pilot hole 10 is the pipe electrode 5
Since the inner peripheral surface 8 of the pipe electrode 5 and the peripheral side surface of the pilot hole 10 are large enough to intersect with each other, discharge is also performed on the inner peripheral surface 8 of the pipe electrode 5,
Prevents the tip of the pipe electrode 5 from being consumed in a pointed shape,
There is an advantage that a large number of oblique holes can be continuously processed.

In the above-mentioned embodiment, the pilot hole was processed by a drill,
Other processing methods may be used, and the same effect can be expected even if the cross section of the prepared hole is not circular.

Further, if the working fluid is jetted and sucked by using the hollow portion of the pipe electrode 5, or if the working fluid is jetted and sucked through the pilot hole 10, the consumption of the pipe electrode 5 is further reduced. Target.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, according to the present invention, when the pipe electrode for processing the oblique hole is delivered at an angle different from that of the oblique hole to be formed, the inner peripheral surface of the pipe electrode and the lower hole are formed. Since the peripheral side surfaces of are formed at the intersecting angle,
During electric discharge machining, not only the outer peripheral surface of the pipe electrode but also the inner peripheral surface of the pipe electrode and the peripheral side surface of the pilot hole are generated, and since the pipe electrode is rotating, the discharge location is partially It has an excellent effect that it can be dispersed without being concentrated and the uneven consumption of the pipe electrode can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining an embodiment of the present invention, and FIGS. 2 to 5 are sectional views for explaining a conventional method. 1 ... Workpiece, 4 ... Pilot hole, 5 ... Pipe electrode, 6 ...
… Slanted hole, 7 …… outer peripheral surface, 8 …… inner peripheral surface, 10 …… lower hole.

Claims (1)

[Claims] 1. A machining method for forming an oblique hole having an angle with respect to a line perpendicular to a machining surface of a workpiece by electrical discharge machining, the diagonal hole being intended to be formed in a preliminary workpiece. Is a different angle, and when the pipe electrode for processing the oblique hole is sent out, a lower hole having an angle at which the inner peripheral surface and the peripheral side surface of the pipe electrode intersect is formed, and then the oblique hole to be formed is formed. An electric discharge machining method for an oblique hole, characterized in that the pipe electrode is fed while rotating in the direction of the hole to perform electric discharge machining.