SU759288A1 - Electrode gap automatic controller - Google Patents

Description

The invention relates to electrical discharge machining of conductive materials.

Known automatic regulators / containing an amplitude detector / voltage comparison circuit of the interelectrode gap and the reference, the error signal amplifier and the motor supply electrode And.

The known automatic regulator of the interelectrode gap by the amplitude values of the current or voltage with a pulse signal conversion system with continuous amplitude modulation of the pulse signal by connecting a pulse signal to the source of a capacitor through a diode contains a switching device connected in parallel with the indicated capacitor, which is supported at the moment of pulse appearance. This device, for example, a semiconductor triode, is controlled in such a way that the voltage generated on the capacitor when the next pulse arrives at the device input, remains unchanged for. Most of the following period.

• 2

pulses, the discharge of a capacitor through a switching device occurs in a short, compared with a period of time, the time interval immediately preceding the moment.

The steps of the subsequent impulse.

The disadvantages of such regulators are low control accuracy when working with a vibrating electrode, for example, when piercing holes of small diameter, as well as a small dynamic control range and, as a result, (5 losing machine productivity.

This is due to the fact that the voltage on the interelectrode gap is promoted in amplitude with the vibration frequency of the electrode. At that moment,

• 2θ when the vibrator leads the electrode to the part, the voltage amplitude is minimal and maximum when the electrode is moved away from the part. Thus, every half-period of oscillation, when the electrode is retracted from the part, the regulator receives false information about the size of the minimum interelectrode gap. This is the reason for the re-adjustment of the process, processing, eliminate

3 759288

which artificially reduces the maximum engine speed during feeding, which reduces the regulation accuracy, reduces the dynamic range of the regulator and leads to a loss of performance.

The purpose of the invention is to improve the control accuracy and expand the dynamic range of the regulator when working with a vibrating electrode when flashing holes of small diameter.

For this regulator containing. . a series-connected amplitude detector, a comparison circuit for · ¹ inter-electrode gap, a reference error amplifier, and an electrode feed motor, equipped with a switching device, made, for example, on a semiconductor triode, which is controlled by an electrode position sensor. The amplitude detector circuit is also equipped with switching -. boron connected parallel to the capacitor of the detector by a controlled differentiated control pulse of the switching device at the input of the amplitude detector.

FIG. 1 shows a diagram of the device; in fig. 2 - oscillograms at various points of the circuit.

The input of the amplitude detector consisting of Diode ί and capacitor 2 is connected to the interelectrode one. the gap of the machine through a switching device consisting of a resistor

3 and transistor 4. Transistor base

4 is connected to the output of the electrode position sensor 5. The voltage from the capacitor 2 is fed to the input of the comparison circuit 6, to the other input of which the reference voltage is applied. Parallel to the capacitor 2 is connected a switching device on the transistor 7, the base of which is connected to the output of the electrode position sensor 5 through a differentiating amplifier 8. You. the course of the comparison circuit 6 through the error signal amplifier 9 is connected to the electrode supply motor 10.

Oscillogram a (Fig. 2) - voltage electrode position sensor, proportional to the instantaneous position of the end of the electrode? δ is the voltage across the interelectrode gap; B - control pulses at the output of the electrode position sensor;

g is the voltage at the output of the differentiating amplifier; d - voltage at the input of the amplitude detector;

e is the voltage at the input of the comparison circuit.

The scheme works as follows. When the electrode vibrates, the interelectrode gap periodically changes with the frequency of vibration, as seen on the oscillogram a. According to h

As a result, the amplitude of the voltage across the interelectrode gap (oscillogram &) periodically changes, which is fed to the input of the amplitude detector through the commutating

5 device of resistor 3 and transistor

4. The base of transistor 4 receives impulses from the electrode position sensor 5 (oscillogram b), controlling the operation of this switching

, 0 of the device so that the transistor 4 is open and does not pass the voltage from the interelectrode gap to the input of the amplitude detector all the time, except for those moments when the interelectrode gap is minimal (15 kilogram d). At these moments trans. Sistor 4 is closed and. capacitor 2 is charged through diode 1 to amplitude voltage. ·

The voltage on the capacitor remains unchanged during most of the oscillation period of the electrode due to the low discharge rate through the input resistance of the reference circuit 6. In the next period

25 oscillations of the vibrator datichk 5 position of the electrode again closes the transistor 4. At the same time at the time, MD action of the leading edge of the pulse at the output of the sensor 5 position

-θ electrode differentiating amplifier .8 opens transistor 7. Capacitor 2 is discharged

. the transistor 7 and its charge through the diode 1 after the end of the action of the front of the control pulse, to the new value of the voltage amplitude at the interelectrode gap.

The voltage from the capacitor 2 is fed to the input of the comparison circuit

40 (oscillogram b), and the error через error through amplifier 9 goes to the electrode supply motor 10, which, depending on the magnitude and sign of the error signal, corrects the electrode gap in one direction or another.

The proposed scheme is reliable in operation, has a high accuracy of regulation with a vibrating electrode and has a large dynamic range. .

Claims (1)

Claim 55 Automatic regulator of the interelectrode gap for EDM machines, containing an amplitude detector connected in series with a switching device connected in parallel to the capacitor of the detector, a circuit comparing the voltage of the interelectrode gap and the reference, error signal amplifier and an electrode feed discharger differing 759288 By the fact that, in order to increase the control accuracy with a vibrating electrode and expand the dynamic range of the regulator, it is equipped with a second switching device at the input of the amplitude detector, 5 a differentiating amplifier and an electrode position sensor, the output of which is connected to the control input 'the second switching device directly, and to the control input of the first switching device through a differentiating amplifier. '