JPS5964224A - Electric discharge machine - Google Patents

Abstract

PURPOSE:To stabilize electric discharge machining, by detecting the fluctuation of the voltage of a DC power source in a charging circuit for a capacitor provided in parallel with the spark gap, to change the switching conditions for a charging switch to keep the charging speed constant. CONSTITUTION:The terminal voltage of a capacitor 5 provided in parallel with a spark gap between an electrode 6 and a workpiece 7 is detected by a detection circuit. A switch 4 is controlled to keep the terminal voltage constant in charging. The fluctuation of the voltage of a DC power source 1b in a charging circuit is detected by a detection circuit 9 to change the switching conditions (on- off frequency, duty factor, etc.) for the switch 4 to compensate for the fluctuation of the voltage to keep the charging speed constant. Electric discharge pulses can thus be stabilized without stabilizing the DC power.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machine, and more particularly, to an electric discharge machine having a machining power supply section using a combination of a transistor and a capacitor (hereinafter abbreviated as Tr-C circuit). .

There is a method that uses a combination of a transistor and a capacitor as a machining power supply method for an electric discharge machine, but currently, a method to keep the terminal voltage of the capacitor constant is a method that detects the terminal voltage of the capacitor and stops switching of the transistor in the charging circuit. There is something.

With this method, the power supply voltage is not stabilized, so if the input voltage fluctuates, the charging speed will fluctuate, making it difficult to maintain stable machining conditions, especially machining speed. there were. As a measure to improve this, a stabilizing power supply device may be added to the processing power supply section, but this is not a good idea as it increases the cost.

FIG. 1 is a schematic circuit diagram of a conventional Tr-C type electric discharge machining apparatus, in which 1 is the above-mentioned stabilized power supply device, 2
is a resistor connected in series with the power supply, 3 is a pulse generation circuit, 4 is a switching transistor, which is turned on and off by the pulse signal from the pulse generation circuit 3,
5 is a capacitor connected in series with a power source, 6 is an electrode for electric discharge machining, and 7 is a workpiece. According to the same configuration, the transistor 4 is turned on and off by a pulse signal from the pulse generation circuit 3 outputted at a constant cycle, and the voltage supplied from the stabilized DC power supply 1a keeps the terminal voltage of the discharging capacitor 5 constant. It was electrical discharge machining. However, with this type of conventional circuit configuration, the price of the stabilized DC power supply 1a is high, and it cannot be said to be the best measure for solving the instability of machining speed due to fluctuations in input voltage.

The present invention has been made in view of the drawbacks in the prior art described above. To provide a low-cost electric discharge machining device which makes the charging speed of a discharge capacitor constant even if there is a fluctuation in the electric discharge voltage, and ensures stable maintenance of the electric discharge machining speed.

The present invention detects the amount of fluctuation in the input power supply voltage, corrects the voltage fluctuation by setting the switching frequency or on-duty of the switching element of the charging circuit of the discharging capacitor or the impedance of the charging circuit to the initial setting, and adjusts the charging speed. This is to keep the value constant.

The present invention will be described in detail below with reference to FIGS. 2 to 6.

FIG. 2 is a block diagram showing one embodiment of the first embodiment.
Items with the same reference numerals as in the figures have the same functions. In FIG. 2, an inexpensive DC power source 1b is connected to the source for electrical discharge machining.

A voltage detection circuit 8 for detecting the voltage between the terminals of the discharge capacitor 5 is provided. Furthermore, a DC power supply voltage detection circuit 9 is provided for detecting the voltage between the terminals of the DC' idler 1b.

That is, a voltage detection circuit 8 that instructs to stop switching is added to the pulse generator 3 that detects the terminal voltage of the capacitor 5 and drives the transistor 4, which is a switching element of the charging circuit, to charge and discharge the capacitor. By detecting the state and controlling the output of the pulse generator 3, the terminal voltage of the discharging capacitor 5 is kept constant.Furthermore, after detecting the voltage fluctuation of the DC power supply 1b, the terminal voltage of the discharging capacitor 5 is kept constant. so that the charging speed of
Charging circuit switching conditions, charging circuit inhibition.

- A voltage detection circuit 9 for changing the dance is added. Therefore, DC power supply 1bK'F! If there is a fluctuation in the L source, it is compared and detected by a shaft ratio device, which will be described later, and the analog data is converted into digital data. As shown in FIG. 3, this data is added to the address of the digital data (voltage fluctuation data) to the address of the data currently set (setting data) in the machining condition setting data bank 10, and then As a result, a command is output to the pulse generator 3 to keep the charging speed constant with respect to the set value.

If the circuits shown in FIGS. 2 and 3 are shown in more detail, the fourth
As shown in Figs. The fourth cell shows the voltage detection circuit 8 that detects the voltage between the terminals of the capacitor 5 in FIG. resistors 16 and 17 and gain adjustment resistors 18 and 1
．． 9, resistors 21, 22, 23 connected to the input section of the operational amplifier 20'3, and an integrating capacitor 24. It consists of 5 resistors.

The analog signal for comparison detection with this operational amplifier is
The signal is input to the A/D converter 33, converted into a digital signal, and input to one of the input terminals of the comparison circuit 26. A digital signal from the voltage setting data output circuit 27 is input to the other input terminal of the comparison circuit 26.

The comparison circuit 26 compares the detection output signal A and the setting data B, the comparison result is determined in the determination circuit, and the output pulse signal turns on and off the switching transistor 29 that controls the pulse generator 3. The transistor 4 is controlled to be turned on or off.

Next, the peripheral circuits of the direct current voltage detection circuit 9 and the power condition setting data bank 10 shown in FIG. 2 and the third factor are shown in FIG. 5 and will be described. Figure 5 shows voltage fluctuation detection 2.
Regarding the frequency converting section, reference numeral is a detecting section that detects the voltage between the terminals of the DC' power supply 1b in FIG. Comparison circuit 31 No. 9
A reference voltage E is input to one input terminal, and the comparison difference voltage is converted into a digital signal by an A/D converter 32 and input as an address signal to a processing condition setting data bank 10 consisting of a memory element. be done. On the other hand, machining pulse conditions are input in advance to the machining condition setting data bank 10 as address signals. Therefore, in the data bank IO, the voltage fluctuation state is detected by the address input from the A/D converter 32, and is output as processed data, and is output to the pulse generator 3.

The pulse generator 3 continuously generates pulses based on the output signals of the capacitor terminal voltage detection circuit 8 and the DC power supply voltage 9, and controls the terminal voltage of the charging capacitor 5 to be kept constant. , constantly detects fluctuations in the DC power supply 1b, and controls on/off of the transistor 4 so that the charging speed of the capacitor 5 is constant with respect to the set value.

This stabilizes the voltage applied between the electrode 6 and the workpiece 7! As with Ryo, there is no fluctuation, and good electrical discharge machining can be obtained.

As is clear from the above-mentioned embodiments, according to the present invention, fluctuations in the power supply voltage are detected and the switching element inserted in the power supply circuit is controlled on and off to keep the charging speed of the discharging capacitor constant. Because it is configured as follows, the price per person (
115), which is a stabilized DC power supply, has the effect of easily maintaining a stable machining speed and providing a good electrical discharge machining device.

[Brief explanation of the drawing]

Figure 1 is an overall block diagram of a conventional discharge power Loe device.
2 to 5 are diagrams for explaining one embodiment of the present invention, in which FIG. 2 is an overall block diagram and FIG. 3 is a second embodiment of the present invention.
FIG. 4 is a partial block diagram for explaining the operation of the figure, and is a circuit configuration diagram specifically showing the discharging capacitor terminal voltage detection circuit of FIG. 2. FIG. 5 is a circuit diagram specifically showing the DC power supply voltage detection circuit of FIG. 2. In FIG. 8... Discharge capacitor terminal voltage detection circuit, 9...
DC power supply voltage detection circuit, 10... Processing condition setting bank, 15... Impedance matching circuit, 20, 31.
... operational amplifier, 26 ... comparison circuit, M ... voltage setting data output circuit, Japan ... judgment circuit, 29 ... transistor, 30 ... voltage detection section, 32, 33 ...
A/D converter. Agent Patent Attorney Masami Akimoto

Claims (1)

[Claims] An electric discharge machining electrode and a workpiece are opposed to each other through a machining gap, a DC power source is connected in series with the electrode and the workpiece, and a switching circuit is provided to control the power supply circuit on and off. An electrical discharge machining device that includes a parallel-connected discharge capacitor connected to a series circuit of an electrode and a workpiece, and discharges the workpiece by the discharge voltage of the capacitor, and the voltage between the terminals of the DC power source is a DC power supply voltage detection circuit that detects the amount of variation in the DC power supply voltage and changes the switching conditions of the DC power supply circuit; and a DC power supply voltage detection circuit that detects the voltage between the terminals of the discharging capacitor and issues a switching stop command to the switching circuit. By providing a voltage detection circuit between the terminals of the discharging capacitor, detecting the amount of variation in the DC power supply voltage, and changing the switching conditions,
An electric discharge machining apparatus characterized in that the electric discharge machining apparatus is configured to correct an amount of variation in power supply voltage with respect to an initial setting so as to maintain a constant charging speed of a discharge capacitor.