JPH0771775B2 - EDM method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electric discharge machining method suitable for electric discharge machining accompanied by rocking machining.

[Prior Art] Conventionally, in performing electric discharge machining, swing machining in which an electrode is swung with respect to a workpiece has been performed. In this case, the electrode is orbited on the swing plane at a constant speed,
Only the axial position perpendicular to the oscillating plane is servo-controlled so as to keep the voltage between the electrode and the workpiece constant, and the orbital motion in the oscillating plane is independent of the voltage between the electrode and the workpiece. It was only controlled so that the specified swing radius would move at a constant speed.

Under the rough machining conditions, this oscillating movement allows the discharge gap to be picked up, so that the stirring ability of the machining powder can be exhibited, and therefore stable machining can be performed. However, under machining conditions with a narrow discharge gap, there is a problem in that machining is not progressed because it is affected by the secondary discharge due to machining powder in the lateral direction, which hinders forward movement in the servo axis direction perpendicular to the oscillating plane. . Further, as the working depth becomes deeper, middle bulge is more likely to occur in the side surface direction due to the secondary discharge. Furthermore, if the orbiting speed is made higher than the moving speed in the servo axis direction, the side surface of the workpiece may be scraped, which is not preferable.

[Problems to be Solved by the Invention] Since the conventional electric discharge machining method performs electric discharge machining as described above, the swing machining in which the electrode orbits at a constant speed on the swing plane can be performed only under rough machining conditions. There was a problem that it could not be used.

The present invention has been made in order to solve the above problems, and makes it possible to apply rocking machining in which an electrode orbits on a rocking plane to finishing machining, and also to perform work on the side surface of the electrode. It is an object of the present invention to obtain an electric discharge machining method capable of preventing the middle bulge.

[Means for Solving Problems] In an electric discharge machining method according to the present invention, an electrode is made to enter toward a workpiece along a predetermined axis and the electrode is made to be predetermined on a surface perpendicular to the predetermined axis. Electrical discharge machining is performed on the workpiece while rotating around the swing radius of, and the voltage between the electrode and the workpiece is constantly measured during the electrical discharge machining so that the voltage becomes constant. In an electric discharge machining method that servo-controls the movement of the electrode in the predetermined axial direction, when the voltage between the electrode and the workpiece is reduced, the machining depth in the predetermined axial direction is changed according to the machining depth. It is characterized in that the electrode is temporarily moved toward the center of the circular path by a larger distance as the depth becomes deeper.

[Operation] In the electric discharge machining method according to the present invention, in order to keep the voltage between the electrode and the workpiece constant, the swing radius is changed according to the machining depth and the movement amount of the servo axis perpendicular to the swing plane, By simultaneously servo-controlling the swing plane and each direction of an axis perpendicular to the swing plane, the machining states in the bottom surface direction and the side surface direction of the workpiece are made equal.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram showing a movement amount in the electrode servo axis direction with respect to a voltage change between an electrode and a workpiece when an electric discharge machining method according to an embodiment of the present invention is carried out. As is clear from the figure, the electrode moves in the servo axis direction by the servo axis movement amount a (μm) with respect to the voltage change v (V).

FIG. 2 is an explanatory view showing the movement of the electrode on the swing plane.
When a voltage change v (V) occurs while the electrode is orbiting at a swing radius R and a velocity ω, the swing radius R is changed by ka as shown in FIG. Here, k is, for example, a function of the working depth, and is set so that the value when the working depth is deep is larger than when it is shallow. This is because when the machining depth is shallow, the side surface area is small and the influence of the machining powder is small, so it is not necessary to change the swing radius greatly, but when the machining depth becomes deeper, the influence of the machining powder is large. Therefore, it is necessary to greatly change the swing radius. In this way, the change in the swing radius and the movement in the servo axis direction are controlled in synchronization.

As described above, according to the present invention, when the voltage between the electrode and the workpiece decreases, the deeper the machining depth in the predetermined axis (servo axis) direction is, the larger the distance is. By temporarily moving the electrode in the direction of the center of the orbit, it is not affected by the secondary discharge in the side direction of the electrode, and the orbiting plane is rotated at a constant speed from the rough machining condition to the finishing machining condition. There is an effect that swing machining can be realized, and further, it is possible to prevent middle bulging of the workpiece due to secondary discharge in the side surface direction of the electrode.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a movement amount of a servo shaft with respect to a voltage change between an electrode and a workpiece when an electric discharge machining method according to an embodiment of the present invention is carried out, and FIG. It is an explanatory view showing the above movement.

Claims (1)

[Claims] 1. An electrode is introduced toward a work piece along a predetermined axis, and the electrode is rotated with a predetermined swing radius on a surface perpendicular to the predetermined axis with respect to the work piece. Electrical discharge machining is performed, the voltage between the electrode and the workpiece is constantly measured during the electrical discharge machining, and the electric discharge is servo-controlled to move the electrode in the predetermined axis direction so that the voltage is constant. In the processing method, when the voltage between the electrode and the workpiece is decreased, the electrode is temporarily moved by a larger distance as the processing depth becomes deeper according to the processing depth in the predetermined axis direction. An electric discharge machining method characterized in that the electric discharge machining is performed in the direction of the center of a circular path.