SU536927A1 - The method of electroerosive metal processing - Google Patents

Description

one

The invention relates to the field of electrophysical processing methods and, in particular, relates to the method of electrical discharge machining of metals.

The known method of electroerosive processing of metals with an LC-generator of pulses connected to the interelectrode gap with a thyristor in the discharge circuit, activated by the signal of the sensor of the reverse half-wave of the current in the charging circuit.

The thyristor in the discharge circuit is switched on at the moment of current transition in the charge circuit through a zero value.

However, the thyristor after passing through the working pulse may not turn off, since not only the discharge current of the capacitor will flow through it, but also the current from the power supply and the charging circuit. Therefore, this method does not allow to achieve reliable operation of the generator at high values of its output power.

The aim of the invention is to increase the reliability of operation and increase the output power of the generator.

This is achieved by the fact that the thyristor in the discharge circuit is turned on at times when the magnetic flux of the throttle generated by the reverse half-wave charging current reaches a value of 50-100% of its maximum value.

FIG. 1 shows a diagram of an LC pulse generator with a thyristor in a discharge circuit; in fig. 2 curves of current and voltage variations on individual generator elements. The generator consists of a discharge thyristor 1, a sensor of a reverse half-wave of a current in a charging circuit 2, a control unit 3, droplets 4 of a charging circuit, a constant current source 5, a capacitor 6, and a discharge inductance

circuit 7. The generator is connected to the interelectrode gap 8, in parallel with which a device is installed to ensure stable operation of the generator at idle 9. In FIG. 2 marked: curve 10 change

voltage on the choke of the charging circuit, curve 11 of the voltage across the capacitor, curve 12 of the change in the current in the charge circuit and the nature of the current 13 in the interelectrode gap. The processing method is as follows.

From the power source 5, the storage capacitor 6 is charged according to the oscillatory law, and first the current flows in the forward direction, and then in the opposite direction, which

illustrated by curve 10. The thyristor is switched on in the discharge circuit at the moment when the reverse half-wave charging current reaches such a value when the corresponding magnetic flux

Drossel 4 is 50-100% of the maximum

the magnitude of the magnetic flux created by the inverse of the polywave current. This creates better conditions for restoring the blocking properties of the thyristor after the flow of a working current pulse 13, since by creating e. d. self-induction in the winding of the chokes 4, directed against the voltage of the power source 5, the opposite voltage is applied to the thyristor. The beginning of the appearance of this e. d. associated with the moment of opening of the thyristor 1, i.e. with the moment of the appearance of a current pulse 13 in the interelectrode gap 8. The operating time of the emf self-induction, it is desirable to choose more than the duration of the operating current pulse 13. After the termination of this pulse, the charge of the capacitor 6 (curve 11) continues under the action of emf. self-induction due to the electromagnetic energy stored in the choke 4. This processing method allows to increase

reliability of the generator and increase its input power, which leads to an increase in the performance of the processing process.

Claims (1)

Invention Formula The method of electroerosive processing of metals with connected to the interelectrode the interval of the LC pulse generator with a thyristor in the discharge circuit, activated by a signal from the sensor of the reverse half-wave of the current in. charge circuit, characterized in that, in order to increase the reliability of operation and, increase the output power of the generator, the thyristor is turned on at times when the magnetic flux of the throttles generated by the inverse polyvolume charge current reaches 50-100% of its maximum value.