JPS6059100B2 - Electric discharge machining equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a machining electrode in an electric discharge machining device, and in particular, the present invention relates to a machining electrode in an electrical discharge machining device. In the event of an emergency such as a power outage, an auxiliary pressure source installed separately from the main pressure source separates the machining electrode from the workpiece (several meters to seven meters) to prevent damage to the machining electrode due to contact with the workpiece. It is an object of the present invention to provide an electric discharge machining apparatus that prevents the above.

Conventional electric discharge machining equipment of this type does not have a mechanism that widens the gap between the machining electrode and the workpiece even if an emergency situation such as a power outage occurs during electric discharge machining, and the gap between the machining electrode and the workpiece is kept in a narrow gap during electric discharge machining. The operation will be stopped while the In this way, in the event of a power outage, etc., if the gap between the machining electrode and the workpiece remains as it was during electrical discharge machining (several microns to several tens of pins), the weight of the electrode and the electrode stand on which it is attached, and the electrode The electrode often moves and comes into contact with the workpiece due to oil leakage from the cylinder that drives the table. In particular, if the electrode is made of a brittle material such as graphite, or if it is a small-diameter electrode or thin plate electrode that is used to process small holes or slits, it has the disadvantage of being easily damaged or deformed by contact with the workpiece. . This invention was made with attention to this point, and it can be used in emergencies such as power outages. When a situation occurs, the machining electrode is separated from the workpiece by an auxiliary pressure source provided separately from the main pressure source to widen the gap between the two, thereby eliminating the above-mentioned drawbacks.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 1 is a pressure oil circuit diagram showing one embodiment of the present invention;
Figures a and b are circuit diagrams showing the switching function of the switching valve device shown in Figure 1, Figure 3 is a circuit diagram showing the excitation circuit of the switching valve device, and Figure 4 is an operation diagram of the switching valve device. .

In the figure, 1 is integrated with a main cylinder 3 that is controlled by pressure oil supplied from one pressure source 2a at a predetermined pressure, and a machining electrode 5 whose discharge gap G with respect to the workpiece 4 is controlled. The attached electrode stand, 3a is a pressurized chamber for electrode stand separation that moves the electrode stand 1 in a direction away from the electrode 5 or the workpiece 4 using pressure oil supplied from the pressure source 2a, and 3b is a pressure source There is an electrode stand approach pressurizing chamber in which the electrode stand 1 is moved in the direction in which the electrode 5 approaches the workpiece 4 by pressure oil supplied from the electrode stand 2a.

6, 6 are a pair of balance cylinders attached to the electrode stand 1 on both sides of the main cylinder 3, and these balance cylinders 6, 6 are controlled by pressure oil supplied from the other pressure source 2b. There is.

In addition, 7a and 7b are check valves, 7-1a and 7-1
b is a pilot type check valve, and when the electrode stand 1 is brought close to the workpiece 4, pressure oil is supplied to the electrode stand approach pressurizing chamber 3b via 7-1a, and this pressure oil is used as a control signal. Pressurized chamber 3 for electrode stand separation from 7-1b when the valve is opened
The oil in a is discharged. Similarly, when separating the electrode stand 1 from the workpiece 4, pressure oil is supplied via 7-1b.
- Drain oil from 1a. Similarly, 7-1c is a pilot-operated check valve, and when a power outage occurs (described later), the electrode stand 1
When the pressurizing chamber 3b is separated from the workpiece 4, the oil in the pressurizing chamber 3b is discharged into the tank. Further, 7-1d is a pilot type check valve for draining oil from the balance cylinders 6,6. Reference numeral 8 denotes a switching valve device, which is connected between an accumulator 9, which will be described later, and a pressure chamber 3a for electrode stand separation.

When the switching valve device 8 is deenergized, the P-A. , B-R connection and P-B. ．． The excitation circuit is composed of solenoid valves 8a and 8b connected A to R, and is constructed as shown in FIG. In FIG. 3, 8a-1, 8b-
1 is an excitation coil for each of the solenoid valves 8a and 8b, 10 is a capacitor in which energy is stored during operation of the electrical discharge machining apparatus, 11 is a backflow prevention diode, and 12 is a rectifier that converts the factory power source 13 into direct current. Further, the connections between the boats of the solenoid valves 8a and 8b are as follows. That is, in the de-energized state shown in FIG. 1, the solenoid valve 8a (7) A boat is connected to the pressure chamber 3a for electrode stand separation via the check valve 7a, and further connected to the pressurization chamber for electrode stand approach. 3b is connected to the control circuit of the pilot check valve 7-1b,
The P boat is connected to the solenoid valve 8b (7) B boat, and the solenoid valve 8b (:I) P boat is connected to the accumulator 9, which will be described later. Further, when the solenoid valve 8b is in the energized state during operation and the energizing source disappears due to a power outage, the solenoid valve 8b maintains the energized state by the energy stored in the capacitor 10, and the solenoid valve 8b
It is configured to be deenergized after a certain time T delay determined by the resistance R of the coil and the capacitance of the capacitor 10.
Note that the solenoid valve 8a (7) B boat and the solenoid valve 8b (7) A boat are closed, and the R boats of the solenoid valves 8a and 8b are connected to the tank. Reference numeral 9 denotes an auxiliary pressure source, such as an accumulator, which is connected between the switching valve device 8 and the other pressure source 2b and stores a predetermined amount of pressure oil from the pressure source 2b.

Note that the capacity of the accumulator is set to be sufficiently larger than the capacity of the main cylinder 3. Next, the operation will be explained. When the electric discharge machining apparatus is operated, the switching valve device 8 is energized and becomes the state shown in FIG. Pressure oil is accumulated in the accumulator 9 during operation of the electrical discharge machining apparatus.

In this state, if a power outage occurs, both pressure sources 2a and 2b
Since the pump drive motor stops, the supply of oil to the main cylinder 3 and balance cylinders 6, 6 is stopped, and the source of bias for the switching valve device 8 is also removed, so the solenoid valve 8a is turned off at the same time as the power outage. Forced. However, the solenoid valve 8b continues to be energized for the above-mentioned running time T. The switching valve arrangement 8 therefore has a second switching function as shown in FIG. 2b. The circuit from the accumulator 9 to the pressurizing chamber 3a for electrode stand separation is opened for a certain period of time, and the pressure oil accumulated in the accumulator 9 is supplied to the pressurizing chamber 3a for electrode stand separation via the solenoid valves 8a and 8b. Then, the electrode stand 1 is moved back. At the same time, the pilot type check valve 7-1c is opened by the control signal from the solenoid valve 8a (7) A boat, and the pressurized chamber 3b for accessing the electrode stand is communicated with the tank. Next, when the time T has elapsed, the solenoid valve 8b is also deenergized, returning to the state shown in FIG. 1, and the pressure oil supply circuit from the accumulator 9 is cut off. Therefore, the electrode stand 1 is moved back by a distance proportional to the delay time T of the solenoid valve 8b, and the gap between the electrode 5 and the workpiece 4 is widened. According to this invention, as described above, a predetermined amount of pressure oil is accumulated in the auxiliary pressure source during operation of the electric discharge machining apparatus, and between the auxiliary pressure source and the pressurizing chamber for electrode stand separation of the main cylinder. A switching valve device is provided, and this switching valve device is configured to open a circuit from the auxiliary pressure source to the electrode separation pressurizing chamber for a certain period of time when the urging source disappears while in the energized state. The pressure oil accumulated in the auxiliary pressure source automatically widens the gap between the machining electrode and the workpiece, even if the machining electrode is made of brittle material, thin, or has a thin wall. This has an excellent effect of preventing the processing electrode from being damaged or deformed by contact with the workpiece.

[Brief explanation of drawings]

Fig. 1 is a pressure oil circuit diagram showing one embodiment of the present invention;
Figures a and b are circuit diagrams showing the switching function of the switching valve device shown in Figure 1, Figure 3 is a circuit diagram showing the excitation circuit of the switching valve device, and Figure 4 is an operation diagram of the switching valve device. . In the drawing, 1 is an electrode stand, 2a, 2b are main power sources, 3 is a main cylinder, 4 is a workpiece, 5 is a processing electrode, 6, 6 is a balance cylinder, 8a, 8b is a direct current solenoid valve,
9 is an auxiliary pressure source.

Claims (1)

[Claims] 1. A main cylinder controlled by a pressure source of a predetermined pressure and equipped with a pressurizing chamber for electrode stand separation and a pressurizing chamber for electrode stand approach, and a balance cylinder controlled by a pressure source of a predetermined pressure. an electrode stand on which a machining electrode is attached and which is driven by the cylinders to control the discharge source by approaching or moving away from the workpiece; and an auxiliary pressure source that accumulates a predetermined amount of pressure oil from the pressure source. and a switching valve device connected between the auxiliary pressure source and the electrode stand separation pressurizing chamber,
The switching valve device has a first switching function that cuts off a circuit from the auxiliary pressure source to the pressurized chamber for separating the electrode stand during energization, and a first switching function that interrupts the circuit from the auxiliary pressure source to the pressurized chamber for electrode stand separation during energization, and auxiliary for a certain period of time when the energization source disappears during energization. An electric discharge machining apparatus comprising: a second switching function that opens a circuit from a pressure source to the electrode stand separation pressure chamber and communicates the electrode stand approach pressure chamber with a tank. 2. The electrical discharge machining apparatus according to claim 1, characterized in that a cumulator is used as the auxiliary finger pressure source. 3 The switching valve device uses two solenoid valves that connect P-A and B-R when de-energized and connect P-B and A-R when energized, and the A port of one solenoid valve is connected when de-energized. It is connected to the pressure chamber for separating the electrode pedestal via a check valve, and is further connected to the control circuit of a pilot check valve connected to the pressurization chamber for approaching the electrode pedestal, and the P port is connected to the B port of the other solenoid valve. and the other P port is connected to the above accumulator, and if a power outage occurs during energization, the other solenoid valve will maintain the energized state by the energy stored in the capacitor and will not operate for a certain period of time than the other solenoid valve. The electric discharge machining apparatus according to claim 1, which is deenergized with a delay.