SU1498828A1 - Apparatus for feeding electroplating baths with pulse current - Google Patents

Abstract

The invention relates to electroplating and can be used to supply electroplating baths with pulsed current. The purpose of the invention is to increase the efficiency of the VA and its reliability. The device contains an alternating current source, an adjustable rectifier 1, a current-limiting element 2, a generator of 3 trigger pulses, a switch 4, parallel n-channel thyristor blocks 5, each of which consists of a main thyristor 6, matching elements 7 and 8, an adjustable delay 9, shaper 10 operating pulses consisting of auxiliary thyristor 11, switching capacitor 12, diode 13, reactor 14, and galvanic bath 15. Improving the efficiency of the device and its reliability is achieved by introducing into each n-channel unit adjustable delay device, two matching elements, the main thyristor and driver working pulses. 2 Il.

Description

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The invention relates to electroplating and can be used to supply electroplating, baths with pulsed current in electroplating workshops of enterprises.

The purpose of the invention is to increase the efficiency of the device and its reliability.

FIG. 1 is a block diagram of the device; in fig. 2 - voltage diagram - currents on individual circuit elements.

The device (Fig. 1) contains an alternating current source, an adjustable amplifier 1, a current-limiting element 2, a generator of 3 trigger pulses, a switch 4, parallel n-channel thyristor blocks 5, each of which consists of a main thyristor 6, matching elements 7 and 8 adjustable delay 9, a driver 10 working pulses, consisting of an additional thyristor 11, a switching capacitor 12, a diode 13, a reactor 14, a galvanic bath 15.

I. The control electrode of the additional thyristor 11 is connected to the output of the generator 3 of the triggering pulses through recalculation - switch 4, delay 9 and matching element 8. The auxiliary thyristor 11 connected in series with the switching capacitor 12 is connected in parallel to the main thyristor 6, the anode of which is through current limiting element

2 is connected to the rectifier 1, and the cathode of the main thyristor 6 is connected to the anode of the plating bath 15. The unlocking generator 3, which is a multivibrator designed for a nominal frequency

30 kHz, with decade dividers connected to its output, is made on integrated circuits. The output frequencies of the generator are 30;

3kHz and 300; thirty; 3 Hz.

Switch 4 is designed to convert a one-shot sequence of low-power pulses into p-stroke, for example into a 3-stroke sequence, i.e. for distributing the trigger pulses across the channel thyristor blocks 5.

The delay of the trigger pulses is produced depending on the division factor of the divider and consists of five sub-bands, i.e. with an oscillator output frequency of 30 kHz delay

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ka is 0.05 ms, and for the 3 kHz and 300, 30.3 Hz subbands, the delays are 0.5 ms, 5 ms 50 ms, and 500 ms, respectively. The switching of the subbands of the frequencies of the enable pulses and their delays are carried out by one control unit synchronously.

Matching elements 7 and 8 are terminal amplifiers, which are completed on a pulse transformer.

The device works as follows.

From the external AC mains, single-phase or three-phase voltage is supplied to adjustable rectifier 1, rectified and smoothed voltage through p-channel blocks 5 is converted into powerful operating pulses and fed to the anode of the galvanic bath 15. P-channel blocks work 5 sequentially, depending on the arrival of the enable signals of the generator 3 through the switch 4, i.e. the frequency of the trigger pulses is n times higher than the frequency of operation of each channel unit 5. The rectified and smoothed voltage through the current-limiting element 2 enters the n-channel blocks 5, which alternately open and close, form steep fronts and cuts of the working pulses. The sequence of operating voltage pulses applied to the anode of the electroplating bath 15 generates operating current pulses in it, which on the surfaces of the products electrically connected to the cathode of the electroplating bath 15 cause precipitation of the metal. Since the electrical resistance of the electrolyte of the bath 15 is the number active, the shape of the operating current pulse replicates the shape of the voltage pulse without phase displacement. The n-channel blocks operate sequentially depending on the arrival of the unlocking signals of the generator 3 through recalculation — switch 4, i.e. the frequency of the trigger pulse generator n times the frequency of operation of each channel unit 5, the number of which is equal to n.

The device works as follows.

At time t, the unlocking impulse of control i (Fig. 2a), coming from the generator 3 of unlocking pulses (Fig. 1) through the switch 4 and the matching element 7 to the control electrode of the main thyristor 6, opens it. When the main thyristor 6 is switched on, the switching capacitor 12 is charged with the one indicated in FIG. 1 with a polarity (Fig. 1) until the voltage of the rectifier 1 (Fig. 2e).

After the time t, necessary for the formation of the required duration of the power working pulse, the control pulse delayed by the adjustable delay 9 arrives at the control electrode of the additional thyristor 11 and opens it, the switching capacitor 12, charged with the one indicated in FIG. 1 polarity, connected in parallel to the main tee, resistor. As a result of the applied negative voltage, the operating current of the main thyristor 6 decreases to zero (Fig. 2b), i.e. it closes. Under the action of the voltage of the rectifier 1, the capacitor 12 is discharged. In order to avoid switching on the main thyristor 6 again, the discharge time of the capacitor 12 to zero is chosen by a large recovery time

thyristor locking properties. By order of the restraining element with the first input

15, the main thyriastor 6 recharges the capacitor 12 with a polarity opposite to that shown in FIG. 1. When the next control pulse arrives at the control electrode of the main thyristor 6, it opens and the switching capacitor 12 is recharged along the circuit: diode 13 - reactor 14 - main thyristor 6 and it

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each channel thyristor unit, the second input of which through the switch is connected to the output of the trigger pulse generator, and the output to the bath anode, characterized in that, in order to increase the device efficiency and its reliability, the driver of the working pulses is completed with series-connected regular shutdown - remote tiristor and commuting

torus 6. Since the switching capacitor 12 and the reactor 14 form an oscillating circuit, the current in this circuit stops when the polarity of the voltage on the capacitor 12 is reversed, i.e. corresponds to that shown in fig. one.

Thus, polarizing current pulses with a fairly steep front and cut through the electroplating bath 15 are not formed due to the charge or discharge of power pulse capacitors with limited operating parameters, including low efficiency, but due to unlocking and locking modern high-speed x power thyristors designed for operating currents of up to several tens of kiloamperes (when connected in parallel) with

a capacitor, a diode and a reactor, the thyristor control electrode being connected to the generator output from the piercing pulses through the switch c and the second matching element, and the auxiliary thyristor control electrode to the output of the generator of the sending pulses through the switch, the delay and the first matching element This diode and follower. the reactor connected to it is connected in parallel to the additional and main thyristors, the additional thyristor is connected in parallel to the main thyristor, the anode of which is connected to the positive output of the rectifier through the current-limiting element, and the cathode is connected to the anode of the galvanic bath.

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IQ is 20 25 988286

Claims (1)

voltage up to 1000 V. The efficiency of the proposed device is 0.83– 0.85, while the efficiency of the known device due to the formation of a working polarizing current pulse due to the repeated switching of the power thyristors and power pulse capacitors does not exceed 0.33 -0.35. The reliability and service life is determined by the working life of the power thyristors and is 10,000 hours, and in the known, 10 cycles of charge-discharge of the power pulse capacitor. Invention Formula A device for supplying electroplating baths with pulsed current, which contains an alternating current source, an adjustable rectifier, a current-limiting element, a trigger pulse generator, a switch and p-channel thyristor blocks, each of which contains a main thyristor, a working pulse generator, and a control circuit including an adjustable delay and matching elements, with the negative terminal of the adjustable rectifier connected to the cathode of the bath, and positive through the current each channel thyristor unit, the second input of which through the switch is connected to the output of the trigger pulse generator, and the output is connected to the bath anode, characterized in that, in order to increase the device efficiency and its reliability, the driver of working pulses is filled with series-connected additional capacitor, diode and reactor , with the control electrode of the thyristor connected to the output of the trigger pulser through the switch c and the second matching element, and the control electrode of the auxiliary thyristor to the output of the generator of the trigger pulses through the switch, the delay and the first matching element, the diode and the reactor connected in series with it, are connected; counter parallel to the additional and main thyristors, the additional thyristor is connected in parallel with the main thyristor, the anode of which through the current limiting element is connected to the positive output of the rectifier, and the cathode is connected to the anode of the galvanic bath. 0 five