JP2554878Y2 - Wire electric discharge machine - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention applies a voltage between electrodes between a wire electrode and a workpiece in a processing tank containing a processing fluid.
The present invention relates to a wire electric discharge machine for processing the workpiece by discharge energy generated between the wire electrode and the workpiece.

[0002]

2. Description of the Related Art Conventionally, a technique for manufacturing a mold using a wire electric discharge machine is widely known, and at present, wire electric discharge machining is indispensable in manufacturing a mold. .

[0003] As such a wire electric discharge machine, various types are conventionally known. For example, a conventional wire electric discharge machine has a capacitor system in which electric energy supplied from a power source is temporarily stored in a capacitor, and then discharged between the two electrodes. Electric energy supplied from an electrode is directly intermittently supplied through a transistor as a switching element. There is a transistor method for supplying the voltage between the poles, and a transformer coupling method using both of them.

FIG. 2 is a conceptual diagram showing a transistor type wire electric discharge machine. In this transistor-type wire electric discharge machine, a wire electrode 1 is connected to a cathode side of a DC power supply 5 through a line 13 via a machining pulse generating transistor 4 and a resistor 3, and a workpiece 6 is connected to an anode of the DC power supply 5. Side through line 14. When the pulse signal from the oscillator is oscillated by the transistor 4, a discharge current is obtained from the power supply 5 through the transistor 4 and functions as a switching element of the transistor 4. EDM is
While supplying a machining fluid from a machining fluid injection nozzle 8 between a workpiece 6 serving as an anode and the wire electrode 1 serving as a cathode, a discharge is generated between the two electrodes, and the workpiece 6 is machined using the discharge energy. It is done by doing.

[0005] By the way, water used as a machining fluid for wire electric discharge machining is generally subjected to an ion exchange treatment, but the electrical insulation of the machining fluid is not as high as that of oil. For this reason, if there is a DC potential between the wire electrode 1 and the workpiece 6, a leakage current flows, causing an electrolytic action on the workpiece. That is, the leakage current flows between the wire electrode 1 and the workpiece 6 in all locations where the machining fluid exists. Then, when the electrolytic action occurs, the workpiece 6 connected to the anode gradually melts, similarly to the elution phenomenon of the metal on the anode side in electroplating. Therefore, in actual machining, this electrolytic action can be said to be effective in increasing the machining speed, but on the other hand, it causes corrosion on the surface of the workpiece 6. In particular, when the workpiece 6 is made of a material composed of a plurality of structurally different elements such as an alloy material, an unbalance occurs in the degree of corrosion. For example, when the workpiece 6 is made of a cemented carbide, cobalt as a binder is selectively eluted, leading to damage due to electrolytic corrosion or the like of the cutting edge, which can be called the life of the mold. Become. The bad phenomenon caused by the leakage current is called electrolytic corrosion, and this causes abnormal wear and chipping at the cutting edge of the mold.

Accordingly, various attempts have been made in the past to suppress electrolytic corrosion. As one of them, a circuit for suppressing electrolytic corrosion by a transformer coupling is disclosed, for example, in Okawa Shuppan Co., Ltd., Applied Mechanical Engineering No. 12, 1988 (monthly magazine) (see FIG. 3). This circuit is inserted between both electrodes of the wire electric discharge machine shown in FIG. 2 and a DC power supply as an adapter (inside of a dashed line 10 in FIG. 3). It converts it into an alternating waveform and suppresses the electrolytic action. In the circuit of FIG. 3, reference numeral 7 denotes a capacitor C incorporated between the lines 13 and 14, and reference numeral 12 denotes a coil L.

[0007]

However, in the case of the above-described circuit for suppressing electrolytic corrosion due to the transformer coupling, for the time being,
Electrolytic action can be suppressed, but not completely. That is, in the processing completion state, the processing stop state, or the state where the wire electrode is disconnected due to some trouble and the processing is interrupted, etc., even if the processing pulse generation transistor is turned off, the leakage current of the transistor, A current induced by electrostatic or electromagnetic coupling on a power supply line or various electric circuits generates a potential difference between the wire electrode and the workpiece. If a potential difference is generated between the wire electrode and the workpiece, and a machining fluid is interposed between the wire electrode and the workpiece, a leakage current flows, so that electrolytic corrosion of the workpiece proceeds. Therefore, it is necessary to prevent leakage current from flowing between the wire electrode and the workpiece at any other time during the electric discharge machining.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to prevent the electrolytic corrosion of a workpiece due to a leakage current, a machining completed state, a machining stopped state, and the like.
An object of the present invention is to provide a wire electric discharge machine in which a wire electrode, a workpiece, and a processing tank have the same potential during non-machining such as a machining interrupted state.

[0009]

SUMMARY OF THE INVENTION The present invention is configured as follows to achieve the above object. That is,
This invention applies a gap voltage between a wire electrode and a workpiece in a processing tank containing a machining fluid, and processes the workpiece by discharge energy generated between the wire electrode and the workpiece. In a wire electric discharge machine, one of the electrodes connected to the wire electrode, the electrode of the opposite polarity connected to the workpiece and the machining tank are in a machining completed state, a machining stopped state, and a non-machining state such as a machining interrupted state. The present invention relates to a wire electric discharge machine configured to have the same potential as each other.

[0010] Alternatively, the present invention applies a voltage between the wire electrode and the workpiece in a processing tank containing a processing fluid,
In a wire electric discharge machine for processing the workpiece by discharge energy generated between the wire electrode and the workpiece, a line serving as one electrode connected to the wire electrode and an opposite polarity connected to the workpiece. A first switch provided in a line for short-circuiting a line serving as an electrode, a second switch provided in a line for short-circuiting the workpiece and the processing tank, and the first switch and the second switch are completely processed. The present invention relates to a wire electric discharge machine having a controller that closes and short-circuits in response to non-machining such as a state, a machining stop state, and a machining interrupted state.

[0011]

The wire electric discharge machine according to the present invention is constructed as described above and operates as follows. That is,
In this wire electric discharge machine, when a command signal is transmitted from the machining control system immediately before the application of the machining pulse, the first switch and the second switch are opened, and a potential difference is generated between the wire electrode and the workpiece. It is in a state where electric discharge machining is performed.
On the other hand, when processing of the workpiece by the discharge energy is interrupted, completed, or stopped, a command signal is transmitted from a processing control system, that is, a controller, and the first switch and the second switch are closed. Accordingly, the wire electrode, the workpiece, and the processing tank are always at the same potential, and no leakage current flows between the wire electrode and the workpiece. Therefore, when the wire electric discharge machine is not performing electric discharge machining, electrolytic corrosion does not occur on the workpiece.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of a wire electric discharge machine according to the present invention will be described below. FIG. 1 is an electric circuit diagram showing an embodiment of the wire electric discharge machine according to the present invention. This electric circuit relates to a transistor type wire electric discharge machine.

In this wire electric discharge machine, a wire electrode 1 is connected to a resistor 3 and a transistor 4 in series via a feeder 2 through a line 13.
Are connected to the cathode side of the DC power supply 5 through a line 13. The workpiece 6 is connected to the anode side of the DC power supply 5 through a line 14. A first switch 20 as a first electrical contact includes a line 15 connecting an electrode-side line 13 connected to the wire electrode 1 and an opposite-polarity electrode-side line 14 connected to the workpiece 6. Connected in the middle of. Therefore, when the first switch 20 is closed, the wire electrode 1 and the workpiece 6 have the same potential, the potential difference between the two becomes zero, and no leakage current flows. The second switch 21 as a second electric contact is provided between the workpiece 6 and the machining fluid 17.
Is connected by a line 16 to a processing tank 30 containing the water. Therefore, when the second switch 21 is closed, the workpiece 6 and the processing tank 30 have the same potential, the potential difference between the two becomes zero, and no leakage current flows. In this case, the first switch 20 and the second switch 21 are connected to the controller 2
It is preferable that the opening and closing operation be performed in synchronization with the command of No. 5.

A control circuit having an oscillator 9 is connected to the base of the transistor 4 and generates a pulse signal whose pulse width and pause time are controlled.

The first switch 20 and the second switch 21 of this wire electric discharge machine are connected to a controller 25.
That is, the opening and closing operations are simultaneously performed by a command signal from the processing control system. That is, immediately before the machining pulse is applied to the electric circuit of this wire electric discharge machine, a command signal is started from the machining control system, and thereby the first switch 2 is turned on.
0 and the second switch 21 are simultaneously opened. On the other hand, at the time of non-machining in the machining completed state, the machining interrupted state, or the machining stopped state, a command signal is started from the machining control system, whereby the first switch 20 and the second switch 21 are simultaneously closed. .

Next, the operation of the wire electric discharge machine will be described. When processing the workpiece 6, the first switch 20 and the second switch 21 are simultaneously opened by receiving a command signal from the processing control system. Subsequently, the transistor 4 is turned on by a pulse signal from the control circuit. First switch 2
Since 0 and the second switch 21 are in an open state, a voltage between contacts is generated when the transistor 4 is turned on. If the distance between the poles is a distance that can cause dielectric breakdown, discharge starts immediately, the two poles discharge, and the workpiece 6 is processed by the discharge energy generated at that time. Then, when the pulse signal reaches the pause time, the discharge stops.
This discharge is repeatedly performed in response to the pulse signal.

When the workpiece 6 is not machined in the machining completed state, the machining interrupted state, or the machining stopped state, a command signal is issued from the machining control system, that is, the controller 25, and the command signal from the controller 25 is received. One switch 20 and the second switch 21 are closed at the same time. As a result, the wire electrode 1 and the workpiece 6 are electrically short-circuited to have the same potential, and the workpiece 6 and the processing tank 30 are also electrically short-circuited to have the same potential. Accordingly, no leakage current flows between the workpiece 6 and the wire electrode 1 or the processing tank 30, so that electrolytic corrosion of the workpiece 6 does not occur, and undesirable electrolytic corrosion does not occur. Processing accuracy can be improved.

In the above embodiment, the transistor-type wire electric discharge machine has been described. However, it is needless to say that the present invention can be applied to the transformer-coupled wire electric discharge machine shown in FIG.

[0019]

The wire electric discharge machine according to the present invention is configured as described above, and has the following effects. That is, this wire electric discharge machine has a first switch provided in a line for short-circuiting a line of one electrode connected to a wire electrode and a line of an electrode of the opposite polarity connected to the workpiece, and the workpiece and Since there is a second switch provided in a line for short-circuiting the machining tank and a controller for short-circuiting the first switch and the second switch in a closed state, other than during electric discharge machining, that is, a machining completed state, machining At the time of non-machining in the interrupted state or the machining stopped state, the wire electrode, the workpiece and the machining tank can always be at the same potential by the command of the controller, and there is no leakage between the wire electrode and the workpiece. No current flows and no electrolytic corrosion of the workpiece occurs. In particular, the cutting edge, which can be called the life of the mold, does not undergo electrolytic corrosion due to leakage current,
Damage to the cutting edge of the mold can also be prevented, and the quality of the machined surface of the workpiece improves.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a wire electric discharge machine according to the present invention.

FIG. 2 is an electric circuit diagram of a conventional wire electric discharge machine.

FIG. 3 is an electric circuit diagram showing a circuit for suppressing electrolytic corrosion caused by a transformer in a conventional wire electric discharge machine.

[Description of Signs] 1 Wire electrode 4 Transistor 5 DC power supply 6 Workpiece 13 Line 14 Line 16 Line 17 Processing fluid 20 First switch 21 Second switch 25 Controller 30 Processing tank

Claims (2)

(57) [Scope of request for utility model registration] 1. An inter-electrode voltage is applied between a wire electrode and a workpiece in a processing tank containing a machining fluid, and the workpiece is displaced by discharge energy generated between the wire electrode and the workpiece. In a wire electric discharge machine to be processed, one electrode connected to the wire electrode, an electrode of the opposite polarity connected to the workpiece, and the processing tank are processed in a non-processed state such as a completed state, a stopped state, and a suspended state. A wire electric discharge machine characterized in that the electric potential is sometimes set to be equal to each other. 2. An inter-electrode voltage is applied between a wire electrode and a workpiece in a machining tank containing a machining fluid, and the workpiece is displaced by discharge energy generated between the wire electrode and the workpiece. In a wire electric discharge machine to be processed, a first switch provided in a line for short-circuiting a line serving as one electrode connected to the wire electrode and a line serving as an electrode of an opposite polarity connected to the workpiece, the workpiece A second switch provided in a line for short-circuiting the processing tank and the processing tank, and closing the first switch and the second switch in response to non-processing such as a processing completed state, a processing stopped state, and a processing interrupted state. A wire electric discharge machine, comprising: a controller that short-circuits the electric discharge machine.