SU1480991A1 - Power source for electric-arc welding - Google Patents

Abstract

The invention relates to an AC power source for electric arc welding with steeply dipping characteristics and can be used in installations for inert gas welding with a non-consumable electrode. The purpose of the invention is to create a single-range power source for electric arc welding with wide control of current limits and expansion of technological capabilities, in particular, obtaining a pulsed current mode. At the source, an additional resistance (inductive or active) is connected in series with the reactive winding of the transformer, which is shunted by anti-parallel connected thyristors. The current limits are controlled by varying the opening angle of the thyristors and by biasing the shunt. The source provides deep regulation of welding current in one range without switching in the power circuit. 1 hp f-ly, 2 ill.

Description

The invention relates to an AC power source for electric arc welding with steeply dipping characteristics and can be used in installations for inert gas welding with a non-consumable electrode.

The purpose of the invention is to create a single-range power source for electric arc welding with wide control of current limits and expansion of technological capabilities, in particular, obtaining a pulsed current mode.

FIG. 1 is a schematic of the proposed power source; in fig. 2 - oscillogram of currents of secondary and reactive windings flowing on the source welding circuit.

The power source consists of a transformer containing a primary magnetic conductor 1, primary 2 and secondary 3 windings, shunt 4, winding 5 bias, reactive winding 6, additional resistance 7, thyristor unit 8. and the primary 2 and secondary 3 windings are mounted on the main magnetic circuit 1 is separated by the magnetic core of the shunt 4, on each rod of which the bias magnetic windings 5 are mounted, and the entire magnetic magnetic circuit is reactive winding 6, in series with which additional resistance is included 7. The thyristor unit 8, with consisting of two parallel-connected thyristors, shunts the reactive winding 6 with the series-connected additional resistance 7. The output terminals of the secondary circuit of the source are connected to the welding torch 9 and to the welded product 10, the primary windings 2 of the transformer are connected to the AC network, winding 5 is magnetized - to an adjustable DC source, and thyristor control circuits 8 are connected to a control pulse shaper with a phase control device.

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The device works as follows.

At idle, the flow created by the primary windings 2 closes along the main magnetic circuit 1 and induces a no-load voltage in the secondary windings 3. The effect of reactive winding 6 in this mode is negligible, since the main flux into the core of shunt 4 practically does not branch because of the presence of a nonmagnetic gap.

In the operating mode, which is close to a short circuit, when the thyristors are closed, the main stream of reactions of the secondary windings 3 is displaced into the package of the shunt 4, the EMF is induced in the reactive winding 6, the anti-phase EMF of the main secondary windings 3.

The short-circuit current is determined according to Ohm’s law by dividing the difference in the emf of the primary secondary 3 and reactive 6 windings by the total resistance of the secondary circuit consisting of the internal inductive resistance of the transformer and the external (active or inductive) resistance 7.

This current value will be minimal for installation. It is depicted in FIG. 2

IN THE FORM OF SINUSOIDS WITH AMPLITUDE.

A further increase in the effective value of the welding current is carried out by opening the shunt thyristors at the appropriate time of the voltage oscillation period. Thus, in FIG. 2 shows the intermediate value of the welding current corresponding to the opening points of the thyristors t and / 2.

At these points, the reactive winding 6 with additional resistance 7 is shunted and the current increases abruptly to the magnitude of the sinusoid with amplitude. Thus, changing the thyristor switching-on moment, the effective value of the welding current is continuously controlled from the minimum value corresponding to the simultaneous action of the secondary 3 and reactive 6 windings with a series connection of additional resistance 7, up to the value of the current determined by the action of the current of the secondary winding 3 in the absence of ka shunt magnetization 4.

A further increase in the welding current is accomplished by changing the bias current of the shunt 4 in a known manner.

Such regulation provides a deep welding of current in one range, i.e., without switching in the power circuit of the source.

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Claims (2)

1. A power source for electric arc welding with a predominantly non-consumable electrode in an inert gas medium with alternating current, comprising a transformer with a magnetised shunt, having a reactive winding covering the entire shunt magnetic circuit and connected in series with the opposite winding of the transformer, characterized in that single-range adjustment of welding current and expansion of technological capabilities, in particular, obtaining a pulsed current mode, the source contains additional resistance and two parallel-connected tistors, with additional resistance connected in series with the reactive winding, and parallel to the circuit consisting of a reactive winding and additional resistance, two anti-parallel connected thyristors are connected. 2. The power supply according to claim 1, is distinguished by a factor of 1 gm, determined by the quotient from that, in order to reduce the activation of the secondary voltage on the internal resistance of the transformer without reactive winding. power, connected in series with the reactive winding, the resistance is in the form of inductance. Thus, changing the time of thyristor switching on, the current value of the welding current is continuously controlled from the minimum value corresponding to the simultaneous action of the secondary 3 and reactive 6 windings when the additional resistance 7 is connected in series to the value of the current determined by the action of the current of the secondary winding 3 at no current bias shunt 4. A further increase in the welding current is accomplished by changing the bias current of the shunt 4 in a known manner. Such regulation provides for a deep welding of current in one range, i.e., without switching in the power circuit of the source. 0 Invention Formula 1. A power source for electric arc welding with a predominantly non-consumable electrode in an inert gas environment with alternating current, comprising a transformer with a magnetised shunt having a reactive winding covering the entire shunt magnetic circuit and connected in series with the opposite winding of the transformer, characterized in that control of welding current and expansion of technological capabilities, in particular, obtaining a pulsed current mode, the source contains additional resistance There are two anti-parallel tistors, an additional resistance is connected in series with the reactive winding, and a parallel circuit consisting of a reactive winding and additional resistance are connected to two anti-parallel connected thyristors. 2. The power supply according to claim 1, of the distinguished power, connected in series with the reactive winding, the resistance is in the form of inductance. -Oh 00 Phie.