JPS62259715A - Electric discharge machine - Google Patents

Abstract

PURPOSE:To make voltage of a working power source constant as well as to prevent electric discharge machining from getting worse even if voltage of a commercial power source is varied to some extent, by setting an electric discharge machining power source down to a voltage stabilizer. CONSTITUTION:If a working current flowing between a tool electrode E and a workpiece W is a low current, for example, such one in a range of less than 10A, a selector switch 14 is closed and a voltage stabilizer 13 is connected to a circuit. With this connection, an output voltage of the stabilizer 13, that is, the constant voltage set to an optional value is connected to the tool electrode E and the workpiece W through a switch 10 and a discharge current limiting resistor 11. Therefore, the setting working current peak value is maintained irrespective of voltage variations in a commercial power source, thus high accurate finishing can be done.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electrical discharge machining device, and in particular, the present invention relates to an electrical discharge machining device, in particular, a constant torque source is connected in parallel between a machining electrode and a workpiece, and the machining electrical discharge machine shown in FIG. There was processing equipment. In FIG. 5, (1) is an AC power source for drawing (hereinafter simply referred to as commercial power source), (81 is a processing power supply device, (4) is a processing electrode, (5) is a workpiece, (
6) is an electrode driving device, and FIG. 6 shows details of the processing power source (3) in FIG. 5. In this Figure 6, (γ
) is a transformer that transforms the voltage of commercial power supply (1), (8a)
~ (8f) is a rectifier that rectifies the output voltage of the transformer, (9
) is a capacitor that smoothes the rectified current voltage to make it into a DC voltage, αQ is a switch that applies the DC power voltage between the electrodes, al) l-11, a current limiting resistor, the figure shows the switch turned on -An oscillation control device that controls off.

Next, the operation of the conventional device will be explained. Commercial power supply (1
) is received by the processing power supply wave f(8), and the processing power supply (3) transfers the voltage of the received commercial power supply (υ) to the transformer (γ).
Transform the voltage to the desired voltage and then rectify it? ,>(8a)-
Connect to (8f).

Thus, '4' rectified by the rectifiers (8a) to (8f)
The voltage is smoothed by a capacitor (9) and becomes fc DC voltage,
This DC voltage is applied to the switch σ0) and the current limiting resistor C
The machining electrode (11) is connected to the workpiece (5) through the electrode drive device (6), and the machining electrode is brought close to the workpiece (5) and a machining current is applied to perform electrical discharge machining. Let's do it.

[Problem that the invention seeks to solve]

By the way, in the above configuration, when the voltage of the commercial power supply (1) is vA, and the maximum voltage applied when the electrodes are open is v8, v is v, = xxvA (x times) converted to rel 0', which is a proportional constant. Also, when the machining electrode and the workpiece are short-circuited by electric discharge to form a closed circuit, the peak value of the current flowing through the circuit is Ov, -v as shown in equation (A).

Mach = □ ... (A) Here, R is the resistance value of the current limiting resistor Ql, Vo is the arc voltage between the electrodes, and OR is the machining current machining (A)
0, which can be easily found from the formula.However, if the voltage VA of the commercial power supply (1) fluctuates and becomes V' = vA+, ΔvA,
The beam value of the machining current is expressed by the formula (B1).

KΔvA = Engineer −−1 · −−(B) Therefore,
When the voltage vA of the commercial power supply (1) fluctuates, the peak value of the power supply current is affected by this fluctuation.

As a result, the predetermined surface roughness cannot be obtained by electrical discharge machining, and the machining speed decreases, resulting in deterioration of caro-e characteristics. /J%
In order to reduce the voltage, a constant voltage device (2
)? In some cases, the device is inserted between the commercial power source (1) and the machining power source (8), but in order to maintain a constant voltage over the entire range in which the machining current can be set, the device is difficult and expensive. There were many shortcomings such as:

This invention was made in order to eliminate the above-mentioned conventional drawbacks, and even when the voltage of the commercial power source fluctuates, the machining current can be reduced only in the case of machining in a low machining current range. The purpose is to provide an economical and inexpensive electrical discharge machining device that maintains the peak value at the selected value and does not deteriorate the machinability of electrical discharge machining. Means] The electric discharge machining apparatus according to the present invention includes a detection means for detecting a current flowing between the electrodes, a constant voltage source that keeps the peak value of the current flowing between the electrodes constant, and a voltage source in which the detected current value is in a low current region. The device is equipped with a control device that applies power from the constant voltage source between the electrodes when the electrode is in the position of the electrode.

[Effect]

The electric discharge machining apparatus according to the present invention uses a constant voltage device as the machining power source during electric discharge machining with a low current, thereby keeping the voltage of the machining power source constant and the peak value of the machining current flowing between the electrodes constant.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained with reference to FIG. 1, in which the same parts as in FIG. 3 are denoted by the same reference numerals. In FIG. ) is the changeover switch that connects the constant voltage device to the circuit, and (18) is the voltage detection between both ends of the current limiting resistor device? Based on this, when the current 'a flowing between the electrodes is in a predetermined low current region, the control device controls the changeover switch a (on) to switch the power source to the constant voltage device (1'i). It has the detailed construction shown in the figure. In other words, I2g+ is a resistor, 4 is a differential amplifier, (g)) is a comparator, (21) is a relay, and 2 is a transistor switch. When , the comparator which sends out the output conducts the υtransistor switch (21), and the relay (21) is energized.As a result, the constant voltage device (08) is applied between the electrodes by the switching operation of the changeover switch (0). Ru.

Next, the operation of the above embodiment will be explained. Commercial power supply(
The processing power supply device (8) receives the voltage of 1). In this example, the commercial power supply (
1) is transformed by a transformer (7) to a desired voltage and connected to rectifiers (8a) to (8f). Rectifier (8
The voltage rectified in steps a) to (8f) is smoothed by a capacitor (9) and becomes a DC voltage. This DC voltage source is connected to the processing electrode (4) through the switch σ0) and the current limiting resistor.
The machining electrode (4) is brought close to the workpiece (5) by an electrode drive device (6), and a machining current is applied to perform machining.

At this time, if the machining current flowing between the machining electrode (4) and the workpiece (5) is a low current, in this embodiment a machining current in the region of approximately 1 OA or less, the changeover switch C14) is closed to set the machining current. Connect the voltage device α3) to the circuit. Constant voltage device (1
3) to the circuit, the output voltage of the constant voltage device (1B+, that is, a constant voltage set to an arbitrary value) is applied to the machining electrode (4) and the workpiece ( When the output voltage of the constant voltage device α3) is set to v8 as the maximum voltage applied when the electrode vB1 is open, v8 is converted to VBki v8.

Now, when the machining electrode (4) and the workpiece (5) are short-circuited due to discharge, the machining current flowing through the circuit causes the current limiting resistor to increase the arc voltage between the R1 electrodes.

When R.R. It can be expressed as

Therefore, the voltage vA of the commercial power supply (1) fluctuates and becomes y/.

= V ±ΔvA, the voltage connected to the machining electrode (4) and workpiece (5) through the switch αQ and the current eye resistor (6) is always VB constant9, and the machining The machining current peak value is not affected by fluctuations in the power supply voltage of the commercial power source (1) and is maintained at the set machining current peak value.

In addition, in the above embodiment, the switch a→ which connects the voltage regulator o91 to the circuit may be a switch (15) composed of an electronic element as in the embodiment of FIG. A constant voltage device (13) is used as a constant voltage source, but as shown in Figure 4, a transformer (7) is used as a constant voltage source.
Instead, a constant voltage transformer σ7) may be used to configure the machining power source.

〔Effect of the invention〕

As described above, according to the present invention, the voltage of the machining power supply in the low current region is configured to be a constant voltage source, so that finishing machining with good reproducibility and high precision can be realized, and the equipment can be made inexpensive. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a machining power supply device of an electric discharge machining apparatus according to an embodiment of the present invention, FIG. 2 is a partial detailed block diagram of FIG. 1, and FIGS. A configuration diagram showing an example, FIG. 5 is an overall configuration diagram showing an electric discharge machining apparatus,
FIG. 6 and FIG. 7 are configuration diagrams showing conventional examples, respectively. In the figure, (1) is a commercial AC power supply, (8) is a processing power supply device,
(4) is a processing electrode, (5) is a workpiece, (8a) to (
8f) is a rectifier, C11) is a current limiting resistor (current detection means), 09) is a constant voltage device, (b) to (16) are changeover switches, and μs) is a control device. In addition, in the figures, the same symbols indicate the same or corresponding parts.

Claims (1)

[Claims] Electrical discharge machining involves rectifying commercial AC power to obtain DC power, applying this DC power between the electrodes of the machining electrode and the workpiece, and reducing the distance between the machining electrode and the workpiece to perform electrical discharge machining. In the apparatus, a detection means for detecting the current flowing between the electrodes, a constant voltage source that always keeps the peak value of the machining current flowing between the electrodes constant, and a constant voltage source that detects the current flowing between the electrodes when the detected current value is in a low current region. An electrical discharge machining device characterized by comprising a control device for applying power between electrodes.