JPS58137524A - Discharge machining device - Google Patents

Abstract

PURPOSE:To prevent a workpiece from being rusted by providing an auxiliary power supply which applies negative electric potential to the workpiece of wire cut discharge machining. CONSTITUTION:Such a pulse voltage as to make a workpiece 2 positive is applied to a wire electrode 3 and said workpiece 2 of a wire cut discharge machining unit, and the discharge machining is performed. Further, the negative pole a nd the positive pole of an auxiliary power supply 13 are applied to the workpiece 2 and machining liquid respectively so that the workpiece 2 is maintained at negative electric potential even in case said machining is finished or interrupted. Thus the workpiece can be prevented from being rusted at finish or interruption of the machining.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining apparatus that uses a conductive machining fluid such as water and has a function of preventing rust from forming on a workpiece. .

In this type of electrical discharge machining equipment, which passes a wire electrode through the machined surface of the workpiece and generates electrical discharge between it and the workpiece to perform arbitrary machined part IBI, cooling of the electrode terminal part, wire electrode, and electrical discharge machined part is required. Furthermore, water is used for the purpose of removing sludge that has formed due to the discharge force. When water is used as a machining fluid in this way, rust occurs on the workpiece. Therefore, for the purpose of reducing the electrolytic action, a rust-preventing substance having a reducing action is mixed into the machining fluid to prevent rust.

According to such a method, although the degree of rusting during machining (g) is reduced while the machining material (g) is flowing out, the rust preventive substance affects the machining characteristics itself. As is well known, when machining is performed using a conductive substance such as water as a machining fluid, the ratio of workpiece removal by electrolysis compared to electrical discharge machining is 10 to 20%, but this The electrical conductivity of the machining fluid is greatly influenced by the electrical conductivity K, and when a reducing substance is mixed in as mentioned above, the ratio changes completely,
Extra effort is required, such as changing processing conditions before starting work.

In addition, because the machining time of electric discharge machining is long, the work may be temporarily stopped during machining and restarted the next day, but if the machining fluid is not supplied and left in the air, the workpiece Because things are usually at the earth level, they are vulnerable to oxidation from the atmosphere, and it is as if no measures are taken to prevent rust. When water is used as a machining fluid, it is often automated, but it is highly likely that it will be left unattended after machining as described above, and rusting of the workpiece may deteriorate the appearance of the product. When the workpiece is a press die, there is a risk that the dimensional accuracy of the die will deteriorate due to rust formation, and the rust must be removed by machining or manual processing, which is troublesome.

Furthermore, when the workpiece is made of carbide,
Another disadvantage was that electrolysis of molecules occurred, resulting in a decrease in hardness.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide an electrical discharge machining apparatus that can reliably prevent rusting of a workpiece during electrical discharge machining.

A feature of the present invention is that an auxiliary power source is provided separately from the electrical discharge machining power source, and the negative electrode of the auxiliary power source is brought into contact with the workpiece, and the positive electrode is brought into contact with the machining fluid, and the machining fluid is connected to the workpiece through the workpiece mounting base. This structure connects the workpiece to a negative electrode, which prevents rust from forming.

The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of an electric discharge machining apparatus using a wire electrode, which is a subject of the present invention, and FIG. 2 is a schematic configuration diagram, partially in cross section, when the present invention is applied thereto. To explain the configuration of FIG. 1, the workpiece mount 1 installed in a processing tank (not shown) is
The workpiece 2 is placed and fixed on the upper surface thereof. 3 is a machining wire electrode wound around a reel 4, which is passed through a machining start hole 5 drilled in the workpiece 2 and is attached to a winding reel 6 provided on the underside of the workpiece, which is consumed during electrical discharge machining. This is to wind up the wire. 7 is a pump nozzle that supplies machining fluid 8 to the electrical discharge machining section. 9 is an AC power source, 10 is a DC power source for processing (DC300V) obtained by rectifying the AC power source, 1
Reference numeral 1 denotes a switch inserted into a DC power supply circuit, and 18 a contactor connected to the wire electrode 5, which is connected to the negative pole of the processing DC power supply through a cable. Well, the positive electrode of the DC power supply 10 is connected to the workpiece 2 by cable. The device closes a switch 11, performs electrical discharge machining on the workpiece using an arc generated in the gap between the wire electrode 3 and the workpiece 2, and electrical discharge machining the workpiece into an arbitrary shape by arbitrarily moving the wire electrode 3. It is something to do.

FIG. 2 shows an electric discharge machining apparatus having the configuration shown in FIG. 1 to which the circuit of the present invention is added.
An auxiliary power source 16 is connected between the processing liquid 8, which is a reservoir 2, and the workpiece 2. This auxiliary power source 13 has a much lower voltage than the processing DC power source 10, and is, for example, a battery (9V) power source. The negative terminal of this auxiliary power supply 13 is a resistor 14t.
The positive electrode is connected to the float electrode fj15 floating on the surface of the machining fluid 8, and is also connected to the workpiece mount 1 through a resistor 16. It is. A pump 17 sucks up the machining fluid 8 in the machining tank 12 and injects it into the electrical discharge machining section through a pipe.

In the electrical discharge machining apparatus having the configuration as shown in the figure, electrical discharge machining is performed by closing the switch 11 in the same way as explained in FIG. Current is being supplied.

Then, when the electrical discharge machining being carried out under program control ends when the operator is absent, such as late at night, the electrical discharge machining is stopped by closing the switch 11.
The drive of the pump 17 is also stopped. Therefore, the workpiece 2
is about to rust, but a minute current from the auxiliary power supply 13 flows through the closed circuit of the float electrode 15 - machining fluid 8 - 1 @ attachment table 1 - workpiece 2 - resistor 14, and the workpiece 2 is rusted. Keep it on the negative side. In this way, when electrical discharge machining is stopped, the workpiece 2 is reduced to 11m by the supply of a minute current from the auxiliary power source 13, and since anions are not soluble in water, the workpiece 2 is exposed to the outside world. The applied oxidation effect is negated, and rusting of the workpiece 2 can be prevented. This prevention of rust is the workpiece 2.
This is performed while the machine is placed on the mounting table 1, and is particularly effective when performing electrical discharge machining again after stopping electrical discharge machining for a long time, or when an operator is involved.

In the above embodiment, the auxiliary power supply that supplies a very small current to the workpiece was explained as being separate from the electrical discharge machining power supply. By configuring and connecting them in the same manner as shown in FIG. 2, the configuration of the power supply device can be further simplified.

As is clear from the above embodiments, according to the present invention, a DC auxiliary power source is configured in addition to the electric discharge machining power source, and when the electric discharge machining is stopped, a minute current is supplied so that the workpiece is on the cathode potential side of the auxiliary power source. Since the workpiece is constructed so that it can flow, rust will not develop even if the workpiece is left in the atmosphere for a long time after electrical discharge machining, and it is possible to prevent the machining accuracy of the workpiece from deteriorating due to rust.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of an electric discharge machining apparatus using a wire electrode, which is a subject of the present invention, and FIG. 2 is a vertical cross-sectional side view of an electric discharge machining apparatus to which an auxiliary power source is added according to the present invention. 1... Workpiece mounting stand, 2... Workpiece, 3...
Wire electrode, 8... Processing fluid, 9... AC power supply, 10
...DC power supply for processing, 11...Switch, 12...
・Processing tank, 16...Auxiliary power supply, 14.16...Resistor, 15...Float electrode, 17...Po agent Patent attorney Masami Akimoto

Claims (1)

[Claims] A workpiece placed in an electric discharge machining tank and a wire electrode arranged in an electric discharge machining chamber are made to face each other across a machining gap, and the positive electrode of the electric discharge machining power supply is connected to the workpiece by a wire electrode. An electrical discharge machining apparatus that connects a negative electrode to an electrode and performs electrical discharge machining by supplying machining fluid to the electrical discharge machining section, wherein the negative electrode is connected to the workpiece, and the machining fluid is brought into contact with the machining fluid in a machining tank. An electric discharge machining apparatus characterized in that an auxiliary power supply is provided, which connects a positive electrode to an electrode that is electrically connected to the workpiece through a workpiece mounting base, and converts the workpiece into a negative electrode.