SU1174498A1 - Device for supplying periodic current with back pulse to electroplating tanks - Google Patents

Abstract

DEVICE FOR SUPPLY plating baths periodic current C. reverse pulses, comprising a power-down three-phase transformer, to the three phases of the secondary winding of which is connected a controllable valve rectifier configured zero scheme and general cathodes compound point connected to the device cathode current control, the reverse current valve, an antiparallel controlled valve rectifier and an anode connected to the anode current control device, a control system, characterized in that In order to increase the efficiency of the device, it is equipped with an additional single-phase transformer, the primary winding of which is connected in parallel to the primary winding of the third phase of the power transformer, and the secondary winding is connected at one end to the common connection point of the secondary windings of the power transformer, and cathode (L backflow valve.

Description

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Cx The invention relates to electroplating and can be used in the processes of electrolytic deposition of metals, in particular silver, through the use of a three-phase alternating current of industrial frequency. A device for supplying electroplating baths with a periodic current with a reverse pulse, containing a power three-phase step-down transformer, is connected to the three phases of the secondary winding of a controlled valve rectifier, made according to the zero scheme and a common connection point of the cathodes, connected to the cathode current control device, a return valve current, connected to the counter-parallel controlled valve rectifier and cathode connected to the secondary winding of the first phase of the transformer, and the anode to the device to anode current control system control 1. However, the device does not allow the regulation of the reverse pulse to 1/3 T, while with a decrease in the duration of the reverse pulse between the forward and reverse currents, a pause occurs, causing the device to idle, which leads to a decrease in the efficiency of the transformer and the converter as a whole. . If the pause length increases and reaches 1 or more, the adhesion strength of the deposited metal and the part being coated decreases, thereby reducing the quality of the coating. The closest to the proposed technical essence and the achieved result is a device for supplying electroplating baths with a periodic current with a reverse pulse, containing a power step-down three-phase transformer, to the three phases of the secondary winding of which a controlled valve rectifier is made, according to the zero scheme and common A cathode connection point connected to a cathode current control device, a reverse current valve connected anti-parallel to a controlled valve rectifier and an anode m is connected to the device controlling the anode current, the control system 2. The circuit device reschenie avoids short-circuiting between the phases as a result of possible overlapping forward and reverse currents by synchronizing pulses, comprising valves with the corresponding voltage windings, in which said valves are included. However, when the cathode current flows in the secondary windings of a power transformer, a direct current magnetic flux is created, and when the anode current flows, the reverse flux magnetic flux in the same magnetic conductor, respectively. Due to the occurrence of direct and reverse sequence magnetic fluxes of close magnitude in the magnetic flux, they short circuit, which is observed during the operation of the device. This leads to a strong overheating of the magnetic circuit, large losses of electricity, reaching 20%, distortion of the shape of the periodic current curve, blockage of the leading edge of forward and reverse pulses. All this reduces the efficiency of the device. In addition, during the operation of a cyanic electrolyte, its temperature rises, which leads to a decrease in the reverse current pulse, as a result, pauses appear between the flow of the forward and reverse currents, leading to idle operation of the device, which also degrades coating quality by reducing the adhesion strength of the deposited metal and the part to be coated. The purpose of the invention is to increase the efficiency of the device. The goal is achieved by the device for supplying electroplating baths with a periodic current with a reverse pulse, containing a power step-down transformer, to the three phases of the secondary winding of which is connected a controlled valve rectifier, made according to the zero scheme and a common cathode connection point connected to the cathode current control device , a reverse current valve connected to the counter-parallel controlled valve rectifier and the anode connected to the anode current control device, the control system It is equipped with an additional single-phase transformer, the primary winding of which is connected in parallel to the primary winding of the third phase of the power transformer, and the secondary winding is connected at one end to the common connection point of the secondary windings of the power transformer and to the cathode of the reverse current valve. FIG. 1 shows a circuit diagram of the device; in fig. 2 and 3 are forms of periodic current curves. A device for supplying galvanic baths with a periodic current with a reverse pulse contains a power step-down transformer 1, to the secondary windings 2-- 4 of which valves 5-7 are connected, which form a controlled valve rectifier, made according to the zero scheme, the common point of cathode connection through the device 8 cathode current control is connected to an output terminal for connecting an anode 9 of a galvanic bath, valve 10, the anode of which is connected through an anode current control device 11 also to an output terminal for connecting an anode 9 of the galvanic bath, and the cathode to the sliding contact 12 of the beginning of the secondary winding 13 of the additional single-phase transformer 14, the primary winding 15 of which is connected in parallel to the primary winding of the third phase of the power transformer 1. The common connection point of the windings 2-4 and the end of the secondary winding 13 of the additional transformer 14 connected to the output terminal to connect the cathode 16 of the plating bath. A device for feeding electroplating baths with a periodic current with a reverse pulse operates as follows. The voltage of the three-phase AC network is supplied to the primary windings of the power transformer 1 and simultaneously to the primary winding 15 of the auxiliary transformer 14. A reduced voltage of the required magnitude from the secondary windings 2-4 is applied to the anodes of the valves 5-7. The rectified half-wave current of three phases obtained from them, the value of which is controlled by the device 8 and regulated by changing the control angles of the valves 5-7, feeds the galvanic bath in the cathode direction, and the current obtained by negative half-voltages of the secondary winding 13 of the additional single-phase transformer 14 and the valve 10, the value of which is controlled by the device 11 and is controlled by changing the magnitude of the discharge voltage by the sliding contact 12 for a period of one third of the period at the moment of absence Direct current current feeds the galvanic bath in the anode direction. Regulation of the magnitude of the reverse pulse. In the range from 0 to 1/3 T, which is carried out by the proposed device, allows to obtain the amplitude of the reverse pulse (Fig. 2), which is sufficient for applying high-quality coatings in cyanide electrolytes due to their good scattering properties at elevated temperatures. electrolyte and without pauses between the flow of direct and reverse currents. The amplitude of the reverse pulse (Fig. 3), obtained using known devices. necessary for electrolytes with weaker scattering ability (glandystosynerdistykh and others). The amplitude of the reverse pulse can be adjusted from zero to the required value, depending on the type of electrolyte, process conditions and asymmetry parameters. The introduction of an additional transformer into the circuit makes it possible to increase the efficiency of the device due to the absence of losses on the heating of the magnetic circuit, the losses of electric power, the elimination of short circuits of the forward and reverse magnetic fluxes due to the absence of a magnetic connection between them; to provide better adhesion of the deposited metal to the surface of the part to be coated, since in the process of coating the pause between the passage of forward and reverse currents there is practically no zero to the maximum value of the reverse pulse; obtain uniform coatings with a minimum thickness variation, which leads to savings in precious metals; eliminate the distortion of the shape of the periodic current curve during the entire electroplating time and apply the device not only in the silvering process, but also in the processes of galvanizing, cadmium plating and copper coating with good coating qualities and savings in the application of metals.

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Claims (1)

PERIODIC CURRENT BATTERY POWER SUPPLY DEVICE WITH A REVERSE PULSE, containing a three-phase power step-down transformer, to the three phases of the secondary winding of which is connected a controlled rectifier rectifier, made according to the zero circuit and a common cathode connection point, the cathode is connected to the control current switched on in parallel with the controlled rectifier and rectifier connected to the anode current control device, control system, characterized in that, with intact w improving efficiency device is provided with a complementary single-phase transformer, the primary winding of which is connected in parallel with the primary of the third phase winding of the power transformer, and the secondary winding is connected at one end to a common junction point of the secondary windings of the power transformer, and the other through the sliding contact - to the cathode of the reverse current valve. Figure 1 0 ’Oh