JPS6238098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electric discharge machining apparatus that performs machining by applying electric discharge to a minute gap between an electrode and a workpiece.

Applying a magnetic field to the machined part during electric discharge machining is highly effective in widening the machining gap, increasing the effect of removing machining debris and cleaning the gap, and enabling stable electric discharge machining.

Conventionally, there are devices in which a magnetic field generating coil is wound around an electrode, but the structure of the electrode and the setting of the electrode become complicated.
Furthermore, since a constant magnetic field is applied, there is a drawback that the magnetic discharge is concentrated in one place, causing problems, especially when machining iron materials.

The present invention eliminates this drawback, and in order to simplify the structure, a magnetic chuck for supporting and fixing the electrode is used to apply a magnetic field to the processed part, and the applied magnetic field is localized instead of a static magnetic field. A moving magnetic field of varying strength is applied to the magnetic field.

The present invention will be explained below with reference to embodiments shown in the drawings.

In FIG. 1, a magnetic chuck 1 for fixing an electrode is provided at the tip of a support spindle of a mechanical device, and a machining electrode 2 is fixedly supported thereon, and electrical discharge machining is performed while facing a workpiece (not shown). Figure 2 is a front view of the electrode fixing surface of the magnetic chuck 1.
A plurality of magnetic poles 3A, 3 are distributed and arranged over the entire fixed surface.
B, 3C, . . . are provided, and the electrode 2 is attracted and fixed to these magnetic poles. In addition, each magnetic pole is surrounded by non-magnetic materials such as stainless steel 4A, 4B, etc. so that they do not affect each other.
It is buried surrounded by 4C... Figure 3 is a front view of the inside of the magnetic chuck, showing independent magnetic field generating coils 5A, 5B, 5C for each magnetic pole.
... will be established. Reference numeral 6 denotes a power source that excites each coil, and supplies the excitation current separately. 7A, 7
B, 7C... are the ON circuits inserted into the excitation circuit of each coil. The off switch is controlled by a sequential control circuit 8, such as a ring counter.

During electric discharge machining, the machining electrode 2 is fixedly supported by the magnetic chuck 1, followed by a servo to maintain a minute gap with the workpiece, and machining is performed by generating pulsed discharge in the gap. Magnetic chuck 1 during processing
The magnetic field acts on the machining gap through the electrode 2. The working magnetic field acts locally on the machining gap by each magnetic pole 3A, 3B, 3C... and the ring counter 8
The excitation currents of the magnetic field coils 5A, 5B, 5C, . . . are sequentially switched by the switches 7A, 7B, 7C, . The movement of the locally acting magnetic field can be arbitrarily controlled by the excitation order of each coil or by the arrangement of the coils.

In this way, a magnetic field is applied locally to the processed part,
By controlling the position of action and moving the magnetic field, electrical discharge machining can proceed extremely stably.
The generated working magnetic field is usually about 100 to 1000 G, and by applying the magnetic field, it helps to start the pulse discharge, and it is possible to stably generate a uniform pulse discharge.The magnetic field also widens the machining gap and improves the machining process. The waste increases the removal of generated gas, decomposed carbon, etc. By moving the working magnetic field, concentration of electric discharge is avoided, and machining debris such as magnetic powder and ions are easily removed while being oscillated and disturbed, thereby enhancing the cleaning effect of the machining gap. Generally, in electrical discharge machining, the decomposition rate of machining fluid controls the machining speed, but the removal rate of discharge gas, decomposed carbon, etc. is high, and the decomposition rate can be increased through stable machining, so the machining speed is increased, and the magnetic field is localized. By acting on and moving it throughout the machining gap, stable machining is performed with the machining gap substantially widened,
This widening of the machining gap allows for hole machining that is larger than the size and shape of the electrode. Since machining can be performed with the machining gap widened in this way, finishing after rough machining can be easily performed using one electrode by controlling the magnetic field. The working magnetic field can be easily changed by power supply control by the excitation power supply 6, and stable processing in any manner can be performed.

Although not shown, the moving speed of the magnetic field can be adaptively controlled by controlling the ring counter 6 according to the state of the machining gap, and the excitation power source 6 can be controlled by the detection signal of the machining gap. In this case, the magnetic field strength can be adaptively controlled. It can also be controlled using a microcomputer or the like.

Despite such movement and change control of the magnetic field, the magnetic chuck 1 does not move either of the magnetic poles 3A, 3.
B, 3C... are always excited and generate a magnetic field, so the adsorption effect of electrode 2 is always working, and it will not fall off, and it can be stably fixed and supported in a specified position and stable machining can be performed. It is possible to combine the action of the magnetic field with the magnetic field on the machined portion.

FIG. 4 explains another embodiment of the present invention, in which a permanent magnet or electromagnet 9 is provided in a magnetic field generating device, and a magnetic field is applied while moving this on the X-Y plane. 10 is an X-axis screw shaft rotated by a motor 12, and 11 is a Y-axis screw shaft rotated by a motor 13, each of which controls the movement of the magnet 9.
As shown in the side cross section, the magnetic poles of the magnetic chuck include a plurality of magnetic poles 3A, 3B, 3C, . move it.

The motors 12 and 13 of the moving shaft are driven and controlled by a control device (not shown), and the magnet 9 is moved to the magnetic pole 3A,
The upper surface on which 3B, 3C, .
Therefore, it is possible to apply a local magnetic field to the machining gap through the electrode attracted to the lower surface of the magnetic pole to move it, and it is possible to apply an attractive force to the electrode. Note that a plurality of magnets 9 are provided instead of one, and a magnetic field can be applied to a plurality of magnetic poles at the same time.

In the above embodiments, the moving speed of the magnetic field acting on the machining gap can be adaptively controlled to enable stable machining depending on the electric discharge state and machining state in the machining gap, even if it is moved at a predetermined constant speed. can. This magnetic field action has a good effect of eliminating machining debris, decomposed gas, etc., and enables stable machining, and the electric discharge is dispersed without being concentrated, so that it can be controlled so that machining can be performed uniformly overall. In addition to moving the part where the magnetic field acts one after the other, it can be moved in a certain regular order or irregularly, and depending on the discharge state, it can be moved to follow or lead the discharge point. be able to. Further, the movable part can be moved not only to the entire machining gap but also to a desired part or a part where stable machining can be obtained. These movement control devices can be easily implemented by adaptive control devices, copying control devices, NC control devices, and others that have been conventionally used to control electrical discharge machining equipment.

In addition, since the present invention uses a magnet chuck fixed to the electrode to generate the magnetic field, it can function without the need for a special magnetic field generator, and moreover, the electrode attracting surface is divided by a large number of magnetic poles. Since a magnetic field is applied to each part of the machining gap, a local magnetic field can be easily applied to each part of the machining gap, and the parts can be moved.

[Brief explanation of the drawing]

FIG. 1 is a partial side view of an apparatus according to an embodiment of the present invention;
Figure 2 is a front view of the chuck surface of the magnetic chuck, Figure 3 is a top view of the magnetic chuck, Figure 4 is a top view of the magnetic chuck.
The figure is a side view of another embodiment. 1 is a magnetic chuck, 2 is an electrode, 3A, 3
B, 3C... are magnetic poles, 5A, 5B, 5C... are magnetic field coils, 6 is excitation electrode, 7A, 7B, 7C...
is a switch, 8 is a sequential control circuit, 9 is a magnet, 1
0 and 11 are screw shafts, and 12 and 13 are motors.

Claims (1)

[Scope of Claims] 1. An electrical discharge machining device that processes an electrode and a workpiece by applying a pulse discharge to a machining gap where they face each other, and a magnetic chuck for supporting and fixing the electrode or the workpiece is provided, and the magnetic chuck comprises means for distributing and arranging a plurality of magnetic poles and for changing the strength of the magnetic field of each magnetic pole, and for locally applying a magnetic field to each part of the supported and fixed electrode by each magnetic pole, and for changing the magnetic field strength. An electrical discharge machining device characterized in that the control is performed by moving a locally acting magnetic field. 2. A magnetic field generating coil is provided independently for each of the plurality of magnetic poles, an excitation power source is provided that independently supplies an excitation current to the magnetic field generation coil, and the excitation current supplied to each coil of the excitation power source is controlled intermittently or by changing its strength. An electric discharge machining apparatus according to claim 1, which is provided with a control circuit. 3. The electric discharge machining apparatus according to claim 1, further comprising a movement control device that has magnets facing each other on the arrayed magnetic poles and moves the plurality of magnets to face each other over each of the magnetic poles.