UA86279C2 - method of power supply of single-phase contact butt welders of alternating current - Google Patents

Abstract

The invention relates to the field of welding, or more precisely - to the method of power supply of single-phase contact butt welders of alternating current. In a method of power supply of the single-phase spot-welding machines of alternating current for power supply of arc welding transformer intended for frequency F, by means of two three-phase two-period controlled rectifiers, which are opposite-parallel connected, voltage is formed with frequency of 3F/4. Each half-wave of voltage is formed by successive commutation of two line voltages, in this case the half-wave of one polarity begins by commutation of the same line voltage, on which the previous half-wave of another polarity is finished. The method provides for powering spot-welding machines for flash welding from three-phase electrical network, which have a single-phase transformer. The pulse shape of obtained voltage contributes to the formation of high quality welded connection, because its coefficient of amplitude Kis less than at welding by sinusoid current. The selected sequence of switching on of line voltage at beginning and end of each half-wave ensures reliable power supply, and in the majority of cases practically smooth curve of welding current. In the case three phases of the electrical network of power supply of welding sets are loaded evenly.

Description

low frequency current (N.V. Podola, S.I. Kuchukrnost.

Yatsenko, Contact butt welding with low currents. For this, the inclusion of thyristors of the synchronizing frequency, "Automatic welding", 1957, Mo1, are, for example, relative to the moment of transition through p.63-72|. The frequency of the current is selected from the row of 16 zeros of the linear voltage A-C (Fig. 1), and further for forms - 2/3, 10, or 5 Hz. In accordance with the chosen frequency of the pulse of one polarity at the moment of time M, the welding transformer should be calculated, which is determined by the specified value of the voltage on the motor. outputs of rectifiers and in magnitude is more than 3.Zms and

The disadvantage of this method is that with less than 10ms, the linear voltage A-B is connected to the welding transformer. A-C. This changes the design of the welding machine. from this formation of a half-wave of one polarity, the known method of frequency conversion is concluded. The next half-wave voltage begins with the number of phases for symmetrization of a single-phase voltage from the same line voltage at which the research ended. SA. That is, at the moment of the joint machines, the welding transformer of the time tz-Y2zhn10ms is connected to the linear voltage -SkA. which is designed for industrial frequency. Further, at the moment of time i4-from-3.3ms, connect the li-

The closest in terms of technical solution is its voltage "VS" and this ends the form of electric power supply of single-phase half-wave voltages of negative polarity. ct machines of alternating current, in which the linear voltages V-C, VzhA, C-A, are calculated accordingly for the wires. frequency P, with the help of two HVs, and at moments of time ifi-i2-1-3.3ms, three-phase two-semiperiod controlled voltage rectifiers -АхВ,-Ста,С-В,-АжВ are connected, where и-3,4,5, 6 - orderers that are connected in counter-parallel, form number of the pulse in the series. Next, the described series of voltage with a frequency of ЗР/4, which we accepted as repeating with a frequency of 12.5 Hz. prototype of I.K. Lebedev, A.A. Pismennyi, Usove- The specified method differs advantageously from rshenstvovanie systems of powering machines for contact-prototype in that the shape of the pulse approaches ktnoy welding by resistance, "Welding and rodst- to rectangular, that is, the coefficient of vennie technology decreases - in the 21st century", Sat. tr. the amplitude of the pulse of the welding current, and the duration of the international conference - Kyiv, Institute of Gom much longer compared to the proto-electric welding named after E.O. Paton, 1998, p. 130-136). conditions for effective heating are created

At the frequency of the power supply B-50Hz, the frequency of co- during reflow welding. At the same time, the three phases of mutation of the ZRE/4 rectifiers correspond to 37.5 Hz. networks are loaded evenly. In addition, the

In this method, during each half-wave, each pair of consecutive pulses of different polarity is switched on and off at the same line voltage. At the same time, the form of the voltage in the line voltage, an emergency situation (a short half-wave of one polarity is close to a bruise) is not created even with the supply of soidal pulses, which is not optimal, because the effect of simultaneously controlling all thyristors, which connected heating of the elementary contacts is due to this linear voltage in both rectifiers. reflow welding is carried out only on This condition also makes it possible to obtain a voltage close to the amplitude values of a sinusoid- a continuous curve of the welding current during deposition, the duration of which during the half-cycle depends on the insignificant load power factor. Thus, an increase in the amplitude ratio of the rectifiers. dy of the current Ka:Im/Id, where Im is the maximum value of the device implementing the described method of current, Id is the effective value of the current, not favorably shown in Fig. 2. It contains two three-phase two-half- affects the quality of welding. In addition, this periodic controlled rectifiers 1 and 2, the amplifier method has low reliability in implementation, therefore, the thyristor turn-off pulse distributor 3, which when changing the polarity of the switching pulses, each synchronization unit 4, single-vibrator pulses 5, of the linear voltage is possible at full - welding current sensor 6, unit for measuring effective thyristors, which included the previous linear current value 7, voltage sensor 8, voltage unit. Otherwise, a short measurement of the effective value of the voltage 9, the processor of the closing of the electrical network through thyristors 10, the memory device 11, the block of both rectifiers is possible. voltage and diagnostic message output

The task of the invention is to eliminate the specified non- 12. Number 13 shows the welding transformer. A method of electric feeder is proposed. The blocks in the device are connected in the following way. lation of single-phase contact machines of alternating current The inputs of three-phase two-semi-periodic controlled current, in which for powering the welding rectifiers 1 and 2 are connected to the phase voltages of the transformer designed for frequency E, powered by A, B and C, and the outputs are parallel to each other using two three-phase two-semiperiodic rectifiers, and the positive output of each of the rectified rectifiers, which are turned on counter-currently, is connected to the negative output of the other in parallel, form a voltage with a frequency of РР/4, which is rectified, and then one combined output through is distinguished by the fact that each half-wave of the voltage is a welding current sensor b, the output of which is connected by series switching of two linear channels to the input of the unit for measuring the effective value of voltages, while a half-wave of the same current polarity, connected to one input of the transformer, is started by switching of the same linear voltage, on the torus 13, and the other combined output - with the other input, which completes the previous half-wave of the other field - transformer 13 The inputs of the transformer 13 are also connected to the inputs of the voltage sensor 8, the output for the arrival of the synchronization pulse described above is connected to the input of the measurement unit, the center of the formation of control pulses of the repetitive voltage 9. Amplifier-distributor With the output. When the polarity of the half-waves of the voltage on the tors of rectifiers 2 and 1 changes, and the input through the outputs of the rectifiers, the processor reads from the output block-vibrator 5 with the output of the processor 10, to the inputs to measure the effective current 7, the measured value is connected to the outputs unit for measuring the effective welding current. If this overcurrent value 7, the effective voltage measurement unit 9, exceeds the maximum allowable value, the minting device 11, the voltage assignment unit, the processor 10 disables the generation of keg pulses and the output of a diagnostic message 12 and the thyristor control block and on the unit for setting the synchronization voltage 4, the input of which is connected to phases A and the output of the diagnostic message 12 gives out - and p. a message about an unacceptable weight value

The device works like this. Processor 170 current. works according to the program contained in When changing the polarity of the voltage half-waves on the memory device 11. When it turns on the output of the rectifiers from negative to positive, the diagnostic unit 10 reads from the output of the effective voltage measurement unit message 12 the processor reads the specified voltage 9 the measured effective value of the voltage, which should be at the output of the rectifiers. At the input of the welding transformer. The estimated value in accordance with the functional dependent value is equalized with the given value, and according to the value recorded in the memory device, the processor 10 corrects 11, the processor 10 calculates the moment of its time for the sub-value of its time to include the following thyris- connection to the welding transformer of letters. Adjustment of its time once in a period is necessary for its A-B voltage. After the arrival of a pulse to form a symmetrical voltage in opposite synchronization from the synchronization unit 4, the processor of them according to the sign of half-waves, and thereby calculates the specified time for it and then forms a switching signal of the saturation condition of the welding trans-disconnect thyristors connected to the linear former. voltages A-B in the rectifier, which forms positive The proposed method of electrical supply is half-wave. This signal enters the input of a single-wave contact machine and passed through the experimental rotor 5, from the output of which a pulse is formed, which, when tested in laboratory conditions on a single-phase machine, coincides along the front with the signal from the output of the K-190P type process machine. 10 was welded, and it has a duration of 33,33ms. Thanks to this continuous and pulsating melting of the rail, the amplified pulse from the output of the amplifier of rolled steel with a cross-section from 7000 to 15000 mm of distributor Z is fed to the control inputs with currents of 200...700A. At the same time, the corresponding thyristors were recorded during the entire time of use in each phase with the help of measuring instruments of the controllability conditions of these thyristors. converters and a multi-channel recorder.

After working out the time, their processor un- It was confirmed that this method allows you to calculate the time of 2-3.3ms and during its execution, to feed from the three-phase electrical network, connect the disconnection pulses to the control inputs of thyristor machines for reflow welding, which torus are connected to voltage A-C. Further, such a one has a single-phase transformer. The form of the impulse is the method of calculating the time intervals iz, imh......H2 and lsu of the received voltage contributes to the formation of high-quality opening pulses are formed on the control of the welded connection, because its coefficient amd thyristors, which are connected according to voltage - amplitude Ki is less than when welding a sinusoid-

AC, -V-C (in the negative half-wave rectifier), direct current. The selected power-on sequence

B-C, B-A (in the positive half-wave rectifier), - linear voltage at the beginning and end of each half-wave

VS-StA (in the negative half-wave rectifier), the forks provide reliable power supply in the majority as well

C-A, C-B (in the positive half-wave rectifier), - in cases, an almost continuous welding curve-

SlA,-AzhB (in the negative half-wave rectifier). of current At the same time, three phases of electrical me-

Next, the processor 10 switches to waiting for the power network of the welding machines to download the synchronization pulses from the synchronization unit 4. They are written evenly.

Willow

А-В А-С В-С В-А сС-А С-В ate 5 15 Se i

These -AnS -V-S -VKA -SZA -S-V -AZV

Fig. 1 in-- 13

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Fig. 2

Computer typesetting A. Krulevskyi Signature Circulation 28 approx.

Ministry of Education and Science of Ukraine

State Department of Intellectual Property, str. Urytskogo, 45, Kyiv, MSP, 03680, Ukraine

SE "Ukrainian Institute of Industrial Property", str. Glazunova, 1, Kyiv - 42, 01601