SU574297A1 - Device for short-circuiting protection at electric erosion machining - Google Patents

Description

one

The invention relates to the field of electrical discharge machining using wire non-profiled electrode tools of various metals and alloys.

Devices are known for preventing Short Circuits during EDM with wire electrode tools, in which they specifically reduce the energy supplied to the erosion gap in order to reduce the likelihood of wire breaks. But it also leads to a decrease in performance during the normal EDM process.

The aim of the invention is to eliminate the disadvantages by limiting the current through the electrode tool during a short circuit.

This is achieved in that a transformer with a rectangular magnetization loop and a delay element are included in the device.

The electrical schematic diagram of the device is shown in the drawing.

An impulse generator 1 through nonlinear element 2 is connected to the winding 3 of transformer 4. The core of transformer 4 is made of an IPG memory magnetic circuit with a pronounced rectangular hysteresis loop, for example, ferrite.

2

IOLT, pulse power amplifier 5 or another power trigger switch (for example, a thyristor or a thyratron) is connected via a nonlinear) 1st element 6 to the winding 7 of the same transformer 4. The output of the pulse amplifier 5 or power switch is connected to an electrical erosion gap, i.e. wire electrode-tool 8 and to the workpiece 9, and in parallel, through the element 10 delaying, nonlinear element 11, to the winding 12 of the transformer. To the winding 13, similarly, through the nonlinear element 14, an auxiliary emulsion generator 15 is connected, connected on the one hand to synchronize the generated pulses through the dividing device 16 and the delay element 17 to the master oscillator, and on the other to the feed regulator 18.

The feed regulator 18, made according to known schemes, the output of which is supplied with a signal from the erosion gap, controls the feed motor 19 and enables the starting of the auxiliary generator 15 to start.

The scheme works as follows. The master oscillator 1 generates current pulses with a frequency f, and the unipolar impulse current passing through the winding 3 does not magnify the BCP core in one of the saturated states. As a result, the current in the winding 7 induced during the reversal of magnetic reversal is amplified by the pulse power amplifier 5, supplied to the electrode tool 8 and performs erosion treatment. At the same time, the working pulse, delayed in element 11, is fed to the winding 12 of the transformer 4.

The turn-on direction of the winding 12 is opposite to that of the winding 3, so that the current pulse passing through it reverses the magnetic circuit into an opposite saturated state of the hysteresis loop of the magnetic circuit.

The subsequent impulse of the master oscillator 1 again remagnetizes the magnetic circuit to its original state, and so on.

When a short-circuit of the electrode-tool 8 on the part 9 occurs, the pulsed current through the winding 12 will sharply decrease due to the puncturing effect of the short-circuited erosion gap and will not be able to remagnetize the magnetic core of the transformer 4 to its original state and that will remain saturated from the previous current pulse of the master oscillator 1. Subsequent pulses from the master oscillator 1 can not be induced in the winding 7 and, thus, at the input of the amplifier 5 power trigger pulses cease to come from and tool-electrode 8 and part 9, stops flowing powerful pulse current, thereby prevents the wire electrode 8 from heating and breakage.

At the same time, the reverse signal of the feed regulator 18 is the trigger signal of the auxiliary pulse generator 15. The pulses of this generator, the passage through the winding 13, which is turned on in phase with the winding 12, make the magnetic circuit reversal to the initial state, which makes it possible to induce the pulses of the master oscillator 1 to the input winding 7 of the power amplifier 5. The frequency of the pulses of the auxiliary generator 15 is synchronized by the pulses of the master oscillator 1, but significantly lower, due to the operation of the dividing device 16.

Since the effective short-circuit current through the electrode-tool 8, which produces a thermal effect, is:

. KZ -I p Ti / 2

where In is the current value in pulse; Tn is the pulse duration;

/ 2 - the frequency of the auxiliary generator,

moreover, the effective current through the electrode will be

ef. . slave where / eff. slave / n Gi / 1,

And it will not have a damaging effect on the electrode tool 8.

At the end of the short circuit (due to the removal of the electrode tool using the feed controller), the last pulse of the auxiliary generator 15 is brought to its original initial state and then the auxiliary generator 15 is turned off by the signal of the feed regulator 18. The current pulses from the master oscillator 1 begin to be induced again.

At the input of the power amplifier 5 with the frequency / and the electroerosive cutting process begins again.

Nonlinear elements, such as diodes, in the winding circuits serve to produce unipolar pulses capable of one-sideally reversing the magnetic core, as well as to limit the reverse effect of the input and output circuits of the power amplifier. Locking of the auxiliary generator 15 with the signal of supply regulator 18 can occur only after the generation of the next current pulse. The delay elements serve to prevent the pulses of the power amplifier and the auxiliary generator from coinciding with the pulses of the master oscillator in time.

Claims (1)

Invention Formula A device for protection against short circuits during electrical erosion processing, consisting of a master oscillator, a power amplifier, an auxiliary generator and a supply controller, characterized in that, in order to limit the current through the electrode tool during a short circuit, A carbon loop connected between master oscillator and power amplifier, the output of which through a delay element is connected with another winding of the transformer, which interacts with an auxiliary generator, which is controlled by a regulator filing. . 7 at