SU256912A1 - Wide-band transistor oscillator for supplying precision electrical discharge machines - Google Patents

Description

(21) 1216952 / 25-08

(22) 05.02.68

(46) 07.07.83. Null 25 (72) M.Sh.Otto, MVV.Koreiblum, V.O. Vengerov and B.Sh.Shulman (71) Experimental Research Institute of machine tools

(53) 621.9.048.4.06 (088.8) (54) (57) 1. PSHROYUDIAPAZONNL transistor POWER GENERATOR FOR PRECISION EDM containing a source of DC voltage connected to v, erosive gap via an isolating diode and power units, controllable blockage preamplifiers and a master oscillator made on the basis of a blocking oscillator that triggers three blocks of standby multivibrators and shapers, characterized in that, in order to produce discharge current pulses of the order of hundreds and thousands of kilohertz, a high-frequency block is introduced into it which is connected in parallel to the erosion gap, and the input is connected to the output of one of the preamplifier blocks 2. The generator is in accordance with claim 1, in order to increase the gain in the high-frequency unit In addition, in the output transformer stages, current-limiting resistances are included in the emitter circuit, and the total erosion load. In the collector circuit of the output stage transistors, the output windings of the start-up transformer are connected between the base and the emitter of the output stage transistors.

3. The generator according to claims 1 and 2, characterized in that, in order to obtain at the output of the generator packets of high-frequency pulses, following with a frequency of up to tens of kilohertz, and current pulses of a stepped forefor with an adjustable pause between pulses and packets, two blocks of standby multivibrators and shapers and inputs of a preamplifier block go out, one of which is connected to the high-frequency block, pulse coincidence circuits are connected, simultaneously connected to the output of the third block of the standby multivibrator and a pad, to the input of which a potential-potential coincidence circuit is connected, and its input through a variable resistance is connected to the input of the indicated block,. and potential input to its output.

transistor generators are known for powering EDM machines, which contain a constant voltage source connected to the erosion gap through a separator; a diode, and power units, controlled by preamplifier units and a master oscillator, made on the basis of a blocking oscillator, which triggers three units of pending multivibrators.

The known transistor oscillators do not provide pulse frequencies of the order of hundreds and thousands of kilohertz, which is necessary for precision EDM machines. The sensor for the elimination of short-circuits in these generators is high-impedance, which in some cases leads to unstable operation of the feed control (especially at high frequencies). The known generators do not provide adjustment of the pause between step-shaped current pulses, which is necessary to increase the stability of the process without wear-free processing modes; do not provide the formation of packets of high-frequency pulses of the order of tens of kilohertz, which are necessary in precision processing modes. In addition, to form impulse parquets in

These generators used an additional device, which complicates their design.

In the described generator, the output stages are simplified, and their constructive execution provides the parameters of high-frequency pulses necessary for precision EDM machines.

The generator has a higher efficiency that improves process stability and provides for regulation of the pause between step-shaped current pulses and high-frequency pulse packets that follow with a frequency up to tens of kilohertz.

The described generator contains a high-frequency unit, the output of which is connected in parallel to the erosion gap, and the input to the output of one of the preamplifier blocks.

A transformer start is used to control the transistors of the output stages of the high-frequency unit, and the output windings of the triggering transformer are connected between the base and the emitter of the transistors of the output stages.

Between the outputs of the two blocks of standby multivibrators and drivers and the inputs of the blocks of preamplifiers, one of which is connected to the high-frequency block, are switched on pulsed coincidence circuits simultaneously connected to the output.

the standby multivibrator unit and the driver, to the input of which a pulse-potential coincidence circuit is connected, and its pulse input through a variable resistance is connected to the input of the specified block, and the potential input is connected to its output.

Fig. 1 is a schematic diagram of the described generator; Fig. 2 shows the same high-frequency unit. The master oscillator 1 controls the 2.2 and 2 preamplifiers, and the latter controls the power blocks 3 and the high-frequency block 4

I set the g1Iy oscillator 1 to be an interlocking oscillator that starts up through separation stages 5 and b / blocks 7, 7, and 7 of the waiting multivibrators — and shapers. At the input unit 7, a potential-impulse-potential coincidence circuit 8 is switched on, and at the output of units 7 and 7, impulse circuits 9 coincidence fall. The device - 10 elimination of short circuits (ULC) is connected to the separation stage 5. Power units 3 and. high-frequency unit 4 contains parallel-connected output stages, which are power transistor switches with current-limiting 1 resistance, have Dwe erosion gap 11 or (when idle the generator), resistance 12, as the total load. High frequency unit 4 is separated from the power units 3 by a diode 13. Power supply of power units 3 is carried out from rectifier 14, and high-frequency block 4 - from rectifier 15. Both rectifiers are connected to a common power transformer 16. Units 2, 2, 2, 7, 7 and 7, ULK 10 dividing askady 5 and 6 and the blocking oscillator are fed .from sources, combined into a unit 17

In the output stages of the high-frequency unit 4 (see Fig. 2), the current-limiting resistances 18 are included in the emitter circuit and the total erosion load 11 is in the collector circuit of transistors 19. The transistors 19 are triggered between the base and the emitter through the windings 20 of the output pulse of the main transformer 21 of the pre-final stage 22. Overvoltage on the collectors of transistors. 19 are eliminated using a common high-frequency damping diode 23, in series with which resistance is included to prevent the rising edge of the current pulses. A chain of diode 23 and resistance is connected in parallel to the total erosion load 11.

The generator works as follows.

Positive pulses from the output of the blocking oscillator through the diodes 24 and 25 are fed to the input, dividing

cascades 5 and b, the transistors 26 and 27 of which in the initial state are open to saturation. On the secondary circuits 28, 29 and 30 of the output pulse transformers of stages 5 and 6 along the in-. Here, the positive pulses, which through diodes 31 and 32 start waiting for {multivibrators using transistors 33 and 34 of blocks 7 and 7, start pulses of a given duration, on-i determined by the value of variable capacitances 35 and resistance 36, then go to the inputs of two-stage formers transistors 37 and 38. The winding 29 of the output transformer of the separation stage 5 together with the diode 39 forms a potential-potential pulse input that is connected to the collector of the transistor 38 of the preamplifier block 7. Transistor 33 to the moment. supplying a positive pulse to the input of the transistor 33 of the standby multivibrator unit l is open until saturation, i.e. diode 39 is also open

During the multivibrator generation of the impulse block 7, the transistor 38 of the driver is locked, i.e. its collector has a negative potential, blocking the diode 39, as a result of which no positive pulses are received at the input of transistor 33. After the multivibrator unit 7 returns to its initial state, the establishment begins, during which the positive pulses of the winding 29 are again fed to the input of the transistor 33, and the moment of the next multivibrator start depends on the amplitude of the triggering pulses. The variable resistance 40 connected between the diode 39 and the base of the transistor 33 makes it easy and simple to regulate the amplitude of the triggering pulses and, consequently, a pause between a pulse of a standby multivibrator unit 7 over a wide range, and the frequency of these pulses can be ten kilohertz .

The pulses from the output of a current source l are fed through diodes 41, 42 and 43 to the inputs of blocks 2, 2 and 2 of preparative amplifiers. The input of block 2 also receives pulses from the output of block 7 through the diode 44, and to the input of the block. 2 pulses from the output of block 7 through diode b.-pyioa 41, 44 and 43, 45 form pulsed cxei-Ej 9 matches. The first cascades on the transistors 46 of the blocks 2, 2 and 2 of the preamplifiers are made according to the emitter follower circuit, and in the initial state the transistors 46 are closed because

The transistors 38 of the "shrowers" in the blocks 7, 7 and 7 are open until saturation and through the diodes 41-45 they shunt the input of the transistors 46. When pulses are formed by multivibrators

blocks 7, 7 and the transistors 3S are closed, therefore, the diodes 41-45 are locked, and the transistors 46 are open. However, if the pulse at the output of block 7 is finished, then the transistor 38 of this block is again open, shunt through diodes 41 and 43 of the transistors 46 of blocks 2 and 2, regardless of the presence of pulses at the output of blocks 7 and 7. Thus, the pause between long pulses is forming. by block 7, pauses are defined by high-frequency packets (pulses from the output of blocks 2 and 2, the first of which starts Hej-ieHee 2/3 of power blocks 3, and the second high-frequency block 4, pulses from the output of block 2 correspond in duration and frequency to pulses at the output of the block. If the duration of the pulses at the output of block 7 is several periods of high-frequency oscillations of the blocking generator, then the output of the generator produces step-like current pulses, and the ratio of amplitudes in such pulses is determined by the number of power blocks 3 connected to the output of block 2 to the number of power blocks 3 connected to output of block 2. If the duration of the pulses at the output of block 7 is equal to the duration of the pulses at the output of block 7, then the generator generates current pulses with a constant ar the plate At frequencies of the order of tens of kilohertz in the high-frequency unit 4, at least 2/3 of the EQs of the transistors 19 are disconnected, and in this case it is a low-power generator of igniting pulses. The internal resistance of this generator can be reduced by a factor of three to four compared with the internal resistance of the ignition pulse generator in well-known wide-range transistor generators due to the parallel operation of two, three, or more output and frequency cascades in the high-frequency unit 4. Thus, the resistance 12, the signal from which is fed to the input of the ULC can be reduced by a factor of three to four, respectively, which will increase the stability of the work feed regulator. ULC at. Short erosion gap eases through diode 47 blocks the separation cascade 5 and, consequently, the power units 3, the output stages of which are powered by rectifier 14. After the electrodes are diluted, the voltage regulator on the erosion gap 11 immediately appears the high frequency unit 4, which does not turn off with short cues, and the operation of separation stage 5 is resumed. At frequencies of the order of hundreds and thousands of kilohertz

the power units 3 are disconnected and the high frequency unit 4 remains the only source of technological current. High-frequency pulses or img-pulses in from the output of the block 2 pre-amplifiers arrive at the input of the block 4o

The use of a start-up transformer between the base and the emitter tran-. In the presence of a common radiator (collector / get an 1S circuit with a common emitter, which has the greatest gain and better frequency properties compared to a circuit with obvcim collector. In addition, the transformer triggering of several output stages from one pre-final cascade 22 reduces the nonsynchronous operation of the transistors 19, which is significant when the required pulse duration is about 10--10-sec.

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Claims (3)

1. MIRCODIC BAND TRANSISTOR GENERATOR FOR POWERING PRECISION ELECTROEROSION MACHINES, containing a constant voltage source connected to the erosion gap through a diode diode and power blocks controlled by blocks, preliminary amplifiers and a master oscillator based on blocking oscillators and blocking oscillators characterized in that, in order to obtain pulses of discharge current with a duration of the order of hundreds and thousands of kilohertz, high frequency pleasing unit, whose output is' connected in parallel erosive gap, and the input - to the output of one of the pre-amplifier blocks. 2. The generator by π. 1, it is important that in the high-frequency unit, in order to increase the gain and improve the frequency characteristics, in the output stages with transformer start, current-limiting resistances are included in the emitter circuit, and the total erosion load .- in the collector circuit of the output stage transistors, the output windings of the starting transformer are connected between the base and the emitter of the output stage transistors. 3. The generator according to claims 1 and 2, characterized in that, in order to obtain at the output of the generator packets of high-frequency pulses following with a frequency of up to tens of kilohertz and step-shaped current pulses with an adjustable pause between * pulses and packets , between the outputs / L of the two blocks of the waiting multivibrate / f ditches and the drivers and the inputs of the blocks f ** of the preamplifiers, one of which is connected to the high-frequency block, pulse matching circuits are included, simultaneously connected to the output of the third block of the waiting multivibrator and a shaper, to the input of which a pulse-potential coincidence circuit is connected, and its input through a variable resistance | connected to the input of the indicated block, and the potential input to its output