JPS5949846B2 - Electric discharge machining method - Google Patents

Description

[Detailed description of the invention] In electric discharge machining, machining with a wide machining gap length is
It is highly effective in preventing abnormal discharges such as arcs and short circuits, and enhancing the effects of removing machining debris and cleaning gaps, thereby ensuring stable electrical discharge machining.

Conventionally, the machining gap was controlled by moving the electrode in the opposing Z-axis direction to widen the gap, and by moving the electrode relative to the X-Y plane perpendicular to the Z-axis, that is, by applying feed to one side. A method has been proposed that controls the width of the machining gap, but since the electrode that forms the machining gap or the workpiece is moved, the operation becomes slow and the machining speed decreases, and the machining accuracy is affected due to errors associated with the movement mechanism. There was a drawback that the performance decreased.

The present invention aims to avoid such disadvantageous movements and to achieve a similar effect in a stationary state by means of magnetic action.

That is, the present invention is characterized in that a magnetic field generating device capable of forming and acting on a magnetic field in at least two directions is provided in the processed portion, and the direction of the acting magnetic field is switched or the intensity is controlled. The following will be explained using one embodiment of the drawings. FIG. 1 is a top sectional view of the processed part, FIG. 2 is a side sectional view, and A
P is the machining gap part where the electrode and the workpiece face each other, and P is the center part. Electromagnetic coils or permanent magnets X, X', Y, and Y' that act to form magnetic fields are installed in the cross direction on this side, and the upper and lower Electromagnetic coil or permanent magnet Z, Z in the Z-axis direction
' is provided. Coil excitation is performed by switching in each direction, and when X is excited, a magnetic field is formed in the direction of 1,
In the direction 2 by Y excitation, in the direction 3 by X' excitation,
A magnetic field is formed in the direction 4 by Y' excitation, in the direction 5 by Z' excitation, and in the direction 6 by Z' excitation. Also, if X (5Y) is excited simultaneously, it will move in the intermediate direction and Z direction, and if Y' and x' are excited, x' and Y' will move in the 7.3' direction.
3' and 4' directions by excitation, 1' by Y' and X excitation
, a magnetic field acts in each of the four directions. The magnetic field generated is 200
G or more is preferable and effective. The action of forming a magnetic field on the processed portion A is performed by switching the excitation of each coil, or by controlling the increase/decrease of the excitation current.

Or according to a preset program. The machining part A, that is, the gap between the electrode and the workpiece, is not shown.
Electrical discharge machining is performed by repeating high-current pulse discharges, which are applied from the Yoroe power source, and the magnetic field that forms acts on these discharge streams, creating a strong interaction that leads to good machining results. I'm nervous. By applying a magnetic field, it helps to start the intermittent and repeated pulsed discharge, makes it easier to discharge, increases the repetition of the discharge, makes it possible to repeat the uniform pulsed discharge, and also works to widen the machining gap. These are based on the magnetic trends of magnetic bodies interposed in gaps such as machining debris, electromagnetic forces acting on discharge currents, etc. FIG. 3 shows a test of the change in discharge gap length when a magnetic field is applied. It shows the width of the gap where machining is performed with a constant discharge pressure, with the horizontal axis representing the magnetic flux G and the vertical axis representing the gap length μ.
shows. Normally, the gap is about 10 μ when no magnetic flux is applied, but it is 20 μ at 100 G and 25 to 3 at 200 to 300 G.
It increases to about 0μ. The experiment shows the results of changing the direction of magnetic flux in the same direction but in the opposite direction, and it can be seen that the changes are almost the same. Of course, the electrical discharge flow in electrical discharge machining flows from the electrode facing the machining gap to the workpiece, or from the workpiece to the electrode, so it depends on the direction of the working magnetic field, especially in the X-Y plane direction and the Z-axis vertical direction. Although they show different tendencies, either method works effectively and widens the machining gap. In this way, the machining gap is substantially widened, which improves the removal effect of machining debris and prevents arcing. Since the occurrence of short circuits is prevented, stable machining can be performed, machining speed increases, and high efficiency finishing machining is possible.

In addition, unlike conventional methods, the electrodes and the workpiece are machined in a stationary state without being subjected to any moving movement, so it is possible to perform the process without compromising the machining accuracy and improve the machining accuracy. Machining can be performed at high speed through stable machining using the magnetic field effect during rough machining, and finishing machining after rough machining can be performed in the same manner as finishing machining using the magnetic field effect, resulting in high precision even with worn electrodes. can be finished.

Further, by controlling the applied magnetic field, it is possible to perform enlargement processing with a desired enlargement amount. and switching the direction of the working magnetic field,
Since the increase/decrease control is based on switching control of the excitation current of the magnetic field forming coil, switching can be performed in each direction in turn with a simple configuration, and rapid switching control can be performed.

Further, a composite magnetic field can be formed by simultaneous action in two directions or in multiple directions, and an alternating magnetic field can be formed in two specified directions. Depending on the direction in which the magnetic field is formed and the switching restrictions, it is possible to perform magnification processing only in a specific direction, and it can work in accordance with the processing shape, allowing various processing modes to be considered. The switching speed is usually about 0.1 Hz to 100 Hz, and if high frequencies are not used very much, and a sufficiently large machining enlargement allowance is required, switching may be performed about 1 times every 1 to 5 seconds.

The switching control of the magnetic field direction shown in Fig. 1 is as follows: 1→2→3→4
,1'. ? →Z. l→3'. l→1'. 1, 1 → 2 → 3
In addition to switching such as →4→5→6, 1→3, 2→4,
5→6 Also, each coil is switched at a predetermined time interval.
→P→2→P→3→P→4→P,l→P→2→P→3→
P → 4 → P, also 1.5 → 2.5 → 3.5 → 4.5, 1
．． 6→2.5→3.6→4.5, 1.6→3.5→2.
Any mode such as 6 → 4.5 can be considered, and the mode most suitable for the processing purpose can be selected and used.

Note that if the excitation current to the coil is an alternating current or inversion pulse, or if the conduction polarity is switched, the direction of the generated magnetic field can be reversed, so X can be used as X', and Y can be used as Y'. , Z' can also be used as Z' to reduce the number of coils.

The magnetic field forming device can be arranged in multiple directions in the radial 2π direction with the point P as the center, and the excitation coil can be concentrated in one place so that only the magnetic poles act oppositely on the processed part.

[Brief explanation of the drawing]

FIG. 1 is a top sectional view of an embodiment of the present invention, FIG. 2 is a side sectional view, and FIG. 3 is a characteristic diagram of an example. X, X', Y, Y', Z, Z' are magnetic field generators, A is the processed part, P is the center point, 1, 2, 3, 4, 5, 1'. −Z
, 7.3l, 3l. l, o. 1' is the magnetic field direction.

Claims (1)

[Scope of Claims] 1. A magnetic field generating device capable of forming a magnetic field in at least two directions on the machining part of an electric discharge machining apparatus that machines the machining part by applying a pulse discharge to the machining part where the electrode and the workpiece face each other. A method of electric discharge machining, characterized in that machining is performed while changing the direction of action of a magnetic field in sequence or according to a program. 2. The magnetic field generating device is provided in the radial direction of the X-Y plane perpendicular to the Z-axis where the electrodes of the machining part and the workpiece face, and the machining is performed sequentially or while switching according to a program. An electric discharge machining method according to claim 1. 3 Place the magnetic field generator in the X-Y direction perpendicular to the Z-axis direction of the machining part.
2. The electrical discharge machining method according to claim 1, wherein the electrical discharge machining method is performed by providing the electrical discharge machining device in a planar direction and machining the electrical discharge machining device in sequence or while switching according to a program.