SU1599163A1 - Pulse generator for electric discharge machining - Google Patents

Abstract

The invention relates to electrophysical methods of metal processing and can be used as a wide-range pulse generators for EDM machines. The purpose of the invention is to increase processing performance by forming pulses of various shapes and amplitudes over a wide frequency range and increasing efficiency by reducing the power control of the power switches of the power amplifier. The pulse generator for EDM contains an EDM gap 1, diode 2, a probe 3, a pulse frequency divider 4, a pulse generator 5, an encoder 6 of the voltage pulse duration code, a shaper 7 for the duration of the pulse, and an ignition pulse generator 8. Introduction of the ROM 9, DAC 10, voltage pulse amplitude controller 11, comparator 12, power amplifier 13, low-pass filter 14, current sensor 15, amplifier 16 and encoder code 17 and pulse shape allows to obtain current pulses of a wide range of frequencies shape and amplitude, thereby improving processing performance as well as efficiency. 2 Il.

Description

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The invention relates to electrophysical methods of metal processing and can be used as a wide-range pulse generator of EDM machines.

The purpose of the invention is to increase the processing performance by forming pulses of various shapes and amplitudes in a wide frequency range and increasing efficiency by reducing the power control of the power keys of the power amplifier,

In Fig. 1) a block diagram of a pulse generator is shown; 2 is an electrical circuit diagram of a power amplifier.

Pulse generator for EDM contains 1 first electrode of diode 2 connected to the first electrode of the electroerosion gap and the sensor 3 input of the sample gap that is connected to the first input of the 4 frequency divider, the second input of which is connected to the master pulse generator 5, and to the third input - the encoder 6 of the voltage pulse duration code; the output of the splitter 4 frequency is connected through the shaper 7 of the pause duration to the generator 8 of firing pulses, the outputs of which are Single: with the first and second electroerosion gap electrodes, series-connected permanent storage device (ROM) 9, digital-to-analog converter (D / A converter) 10, voltage pulse amplitude regulator 11, comparator 12, power amplifier 13, low-pass filter 14, sensor 15 current and voltage amplifier 16, the output of which is connected to the second input of comparator 12, the output of current sensor 15 is connected. also with the second electrode of the diode. The first ROM input is connected to the encoder 17 of the code and pulse shape. One of the embodiments of the power amplifier 13 (see FIG. 2) contains the first resistor 18, the first terminal of which is connected to the base of the transistor 19, the collector of which is connected to the anode of the pie diode 20 and the first terminal of the first winding 21 of the current transformer 22, the second terminal of which connected to the first output of the second resistor 23 and the anode of the second diode 24, the cathode of which is connected to the cathode of the first diode 21., the second winding 25 of the transformer 22

Q 5 Q Q with p.

five

current is connected to the base-emitter junction of the second transistor 26, the collector of which is connected through the third winding 27 of the current transformer 22 to the positive bus 28 of the first power supply, the negative bus of which and the emitter of the second transistor 26 are connected to the output buses 29, 30, the input bus 31 connected to the second output of the First resistor 18, the second output of the second resistor 23 and the cathode of the second diode 24 are connected respectively with negative and positive. 32.33 tires of the second power supply, the positive bus 33 of which through the third resistor 34 is connected to the base of the first transistor 19.

The pulse generator (figure 1) works as follows.

After the pause formed by the shaper 7, the generator 8 gives a pulse 1 MP. At the time of the breakdown of the MP 1 detected by the Sensor 3 breakdown, the output signal of the sensor 3 breakdown allows the pulse frequency divider 4 to be transmitted to its second generator input 5 pulses. The division factor of the divider 4 frequency, set by the encoder 6 of the voltage pulse duration code, determines the duration of the current power pulse in the interelectrode gap 1, as

about I1I it.t. G F

where (T-J is the required duration

and current pulse; p. is the coefficient dividing the divider 4 frequencies; F is the pulse frequency from the generator of 5 pulses.

The output signal (counter bits) of the 4 frequency divider blocks for the duration of the current pulse duration; the shaper 7 of the pause duration and, arriving at a part of the address inputs of the ROM 9, generates point codes at the data outputs of the ROM 9 (1urm of the voltage pulse from a certain memory area of the ROM 9, which is set by feeding the remaining encoder of the ROM 9; 17 of the pulse shape code, the voltage with which the required current is selected - the current pulse shape in the interelectrode gap 1. Codes

points of the current pulse shape, by which it is approximated, are preliminarily recorded in the corresponding memory area of ROM 9 and stored in it permanently. The output signal from the data outputs of ROM 9 enters the DAC 10, which forms the voltage pulse waveform from the digital code impulse of a given form. A pulse of a given voltage form from the output of the DAC 10 through the regulator 11 amplitude of the voltage pulse, the magnitude of the output signal of which determines the amplitude of the current pulse in MP 1, goes to the nepBbu i input of the comparator 12, to the second input of which comes through the amplifier 16 a sensor 15 signal current.

The signal arriving at the second input of the comparator 2 is proportional to the current value of the current in the interelectrode gap 1. It is compared with the current signal value applied to the first input of the comparator 12 by changing the amplitude of the voltage pulses 12 by the voltage regulator 11 to the first the input of the comparator 12, there is a change in the amplitude of the current in the interelectrode gap I.

Depending on the sign of the difference of the signals, the output signal of the comparator

12 controls power amplifier 13 (turns transistor switches on or off). Moreover, the switching frequency of the comparator 12 is very high and is determined by the speed and accuracy of its operation. Amplifier output

The power is filtered by the low-pass filter 14, which, by filtering the signal with the switching frequency of the comparator 12, selects a current pulse of the required form and, through the series-connected current sensor 16 and (separation) diode 2, separating the ignition and power voltages, enters MP 1. The signal taken from the first output of current sensor 15 is amplified by amplifier 16 and is a feedback signal supplied to the second input of comparator 12, which is compared with the signal fed to the first input of comparator 12. Thus The voltage pulse shape is converted into a current pulse shape.

After the end of the current pulse of the required form with a signal from the output of the 4 frequency divider, it arrives at the input of the former 7 for the duration of the pause -.

the formation of a pause begins and the process of work is repeated from the beginning.

The number of current pulse shapes is determined by the memory size of the ROM 9 and can take on virtually any value by increasing it.

The circuit of the amplifier 13 power (figure 2) works as follows.

At a low input level, due to the current flowing through the resistor 18 and the base-emitter junction of the transistor 19, the latter is open, i.e. through the winding 21 of the current transformer 22

15

thirty

five

A current is flowing, the value of which is no more than several tens of milliamperes and is mainly determined by the resistance of the resistor 23. When the input level takes a positive potential, the transistor 19 is turned off and the accumulated magnetic field energy of the current transformer 22 causes voltage surges of the reverse polarity simultaneously on all three windings 21,

25 25 and 27 transformer 22 current. Choosing the voltage on the winding 25 causes a regenerative turn on of the transistor 26 due to positive feedback through the winding 27,

When the input level again takes a low potential, the transistor 19 is turned on again and, together with the diode 24, shunts the winding 21 of the current transformer 22, which leads to the cessation of the flow of control current in the winding 2 1 and, consequently, to the flow of current in the load connected to output circuit. As soon as the current in the load ceases, a magnetizing current begins to flow in the winding 21 of the current transformer 22, and the whole cycle repeats.

Claims (1)

Invention Formula five A pulse emitter for electro-erosion treatment containing the first electrode of the diode and the sample probe input connected to the first electrode of an electrodrost gap of the electroerosion gap, the output of which is connected to the first input of the frequency divider, to the second input of which is connected the master oscillator and pulse 5, and to the third input - the encoder of the pulse duration code - for example, the output of the frequency divider is connected to the generator of the pause duration to the third input 0 pulses whose outputs are connected to the first and second electroerosive gap electrodes, characterized in that, in order to increase processing performance due to the formation of pulses of various shapes and amplitudes in a wide frequency range and increase efficiency by reducing the power of the power switches of the power amplifier , a sequential storage device, a digital-to-analog conversion voltage pulse amplitude controller, comparator, power amplifier, low pass filter, current sensor, voltage amplifier whose output is connected to the second input of the comparator, the second output of the current sensor is connected to the second electrode of the diode, the first input of a permanent memory connected to the output of the frequency divider, and the second input of the permanent storage device is connected to the encoder code and pulse shape. - where FIG. 2 .