Arc welding device

Abstract

FIELD: welding production.SUBSTANCE: invention which can be used in arc welding with coated electrodes, for example when performing repair work on magnetized pipelines. The device comprises a control unit and a welding current source, the positive output of which is configured to be connected to a coated electrode, and the negative output is configured to be connected to a welded product, while it is equipped with a second welding current source, a chain of series-connected diodes, a stabilizing diode, a reverse diode, and a transistor. The positive output of the second source is connected to the anode of the reverse diode and, through the said chain of diodes, to the cathode of the stabilizing diode and the collector of the transistor, the base of which is connected to the control unit, wherein the cathode of the reverse diode is connected to the positive output of the welding current source, and the negative output of the second source is connected to the anode of the stabilizing diode, the emitter of the transistor, the corresponding output of the control unit and the negative output of the welding current source.EFFECT: ensuring the technological stability of the arc welding process at low values of welding current and eliminating sticking of the electrode.1 cl, 1 dwg

Description

[0001] The invention relates to arc welding with coated electrodes and can be used when performing repair work on magnetized pipelines.

[0002] A prior art device for welding magnetized pipelines (RU Patent 199253, published August 24, 2020, IPC B23K 9 / 09) is known. The device comprises a welding rectifier with a drooping volt-ampere characteristic, an inverter-commutator with a control unit, and a controller. The device further comprises a push-pull high-precision inverter and an electronic unit for regulating the welding current amplitude. The inverter-commutator is capable of smoothly regulating the welding current frequency within a specified range, and the controller is capable of controlling the push-pull high-frequency inverter and the electronic unit for regulating the welding current amplitude of positive and negative polarity within a specified range.

[0003] The disadvantage of the technical solution is the automatic regulation of the current amplitude of positive and negative polarity, which can lead to sticking of the electrode when the current becomes less than necessary and to an increase in spatter during periods of increased welding current.

[0004] A device for arc welding with controlled transfer of electrode metal is known (patent RU 2359796, IPC B23K9 / 173, B23K9 / 095), containing a DC power source, a transistor, a choke, a current sensor, a control unit and an electrode.The device is additionally provided with N-diodes, a zener diode and a delay line connected in series and in accordance with each other, wherein the choke is made with a saturable magnetic circuit and a sectioned winding, the extreme terminals of which are connected, respectively, to the "plus" terminal of the power source and to the electrode, and a tap from it is connected to the anode of the first diode, the cathode of the N-diode is connected to the cathode of the zener diode and to the collector of the transistor, the emitter of which is connected to the anode of the zener diode and the "minus" terminal of the power source, the current sensor is connected between the "minus" terminal of the power source and the welded product and is connected via a delay line to one of the inputs of the control unit, the other input of which is connected to the electrode, and the output of the control unit is connected to the base of the transistor.

[0005] The disadvantage of this technical solution is the difficulty of monitoring the voltage across the interelectrode gap with the required accuracy, which could potentially lead to a disruption of the operating algorithm and increased metal spatter during welding.

[0006] A device is known for arc welding magnetized pipelines with coated electrodes (patent RU 2797673, published 06 / 07 / 2023, IPC B23K9 / 09, B23K9 / 173, B23K9 / 10), containing a welding current source, a current inverter with a control unit and an electrode. The device is additionally provided with a network switch and a relay with two normally open contacts, wherein the current inverter is connected via the “plus” and “minus” input terminals to the corresponding “plus” and “minus” output terminals of the welding current source, and is connected via the “electrode” output terminal to the electrode and has an “article” output terminal for connection to the article, wherein one normally open contact is connected to the “plus” and “electrode” terminals of the current inverter, and the other normally open contact is connected to the “minus” and “article” terminals of the current inverter, wherein one output of the control unit is connected to the input of the current inverter, a relay is connected to the other two outputs, and the network switch is connected to the input of the control unit.

[0007] The disadvantage of the technical solution is the lack of feedback between the welding current source and the voltage across the interelectrode gap. This does not allow the current to increase at the moment of short-circuiting the interelectrode gap with a drop of molten electrode metal, and at low arc current values, this will lead to sticking.

[0008] The technical result consists in ensuring the technological stability of the arc welding process with consumable electrodes and implementing the possibility of modulating the magnitude of the welding current, and the automatic increase in the welding current during the short-circuit period of the interelectrode gap eliminates sticking of the coated electrode.

[0009] The technical result is achieved in that a device for arc welding with coated electrodes, comprising a control unit and a welding current source, the positive output of which is configured to be connected to a coated electrode, and the negative output is configured to be connected to a welded product, in accordance with the proposed solution, is provided with a second welding current source, a chain of series-connected diodes, a zener diode, a freewheeling diode and a transistor, wherein the positive output of said second source is connected to the anode of the freewheeling diode and through said chain of diodes - to the cathode of the zener diode and the collector of the transistor, the base of which is connected to the control unit, wherein the cathode of the freewheeling diode is connected to the positive output of the welding current source, and the negative output of said second source is connected to the anode of the zener diode, the emitter of the transistor,the corresponding output of the control unit and the negative output of the welding current source.

[0010] Fig. 1 shows a functional diagram of a device for arc welding with coated electrodes, comprising a welding current source 1, the first output of which is connected to a coated electrode 2, the second output is connected to a product 3. A second welding current source 4 is additionally introduced, the “plus” terminal of which is connected to series-connected diodes 5, wherein the cathode of the last diode 5 is connected to the cathode of a zener diode by the collector of a transistor 7, the emitter of the transistor 7 is connected to the anode of a zener diode 6 and the “minus” terminal of the second welding current source 4, and the base of the transistor 7 is connected to the control unit 8. The positive output of the additionally introduced welding current source 4 is connected to the positive output of the welding current source 1 by a reverse diode 9, and the negative outputs of the additionally introduced second welding current source 4 and the welding current source 1 are connected directly.

[0011] Welding current source 1 has a current regulation limit of 20 to 60 A, and the additionally introduced second welding current source 4 has a current regulation limit of 60 to 200 A.

[0012] The arc welding device operates as follows. Direct current from welding power source 1 is supplied to coated electrode 2 and workpiece 3. An electric arc is ignited between electrode 2 and workpiece 3, causing electrode 2 to melt and a drop of liquid metal to form, which flows onto workpiece 3, forming a bridge (Fig. 1 not shown).

[0013] At the moment when a liquid metal bridge exists, the voltage on the interelectrode gap becomes less than the voltage drop on the chain of series-connected diodes 5 and transistor 7, the current of the second welding current source 4 through the reverse diode 9 flows through the coated electrode 2 and the product 3. The total current of welding current sources 1 and 4, flowing through the bridge, ensures the maintenance of the liquid state of the bridge, the flow of a drop of molten metal of the coated electrode 2 onto the product 3, after which the bridge naturally disappears, and an electric arc is ignited between the coated electrode 2 and the product 3.

[0014] At the final moment of the jumper's existence, the voltage drop across it exceeds the voltage across the chain of series-connected diodes 5 and transistor 7, and the current of the second welding current source 4 stops flowing through the coated electrode 2 and the product 3 and again flows through the chain of series-connected diodes 5 and transistor 7. This ensures the destruction of the jumper at a low current value through it and, accordingly, the exclusion of its explosion, and reduces metal spatter.

[0015] Control unit 8 turns off transistor 7. In this case, the voltage at the output of welding current source 2 increases to a value sufficient for current to flow through reverse diode 9 to coated electrode 2 and product 3.

[0016] As a result, the burning current of the electric arc is equal to the sum of the currents of welding current sources 1 and 4. To complete the pulse, the control unit 8 turns on the transistor 7. The current of the welding current source 2 stops flowing through the coated electrode 2 and the product 3, and again flows through the chain of series-connected diodes 5 and transistor 7.

[0017] Thus, the proposed solution ensures the technological stability of the arc welding process with coated electrodes at low values ​​of welding current and the possibility of its amplitude modulation; the automatic increase of the welding current during the short-circuit period of the interelectrode gap eliminates sticking of the coated electrode.

Claims

A device for arc welding with coated electrodes, comprising a control unit and a welding current source, the positive output of which is configured to be connected to a coated electrode, and the negative output is configured to be connected to a welded article, characterized in that it is provided with a second welding current source, a chain of series-connected diodes, a zener diode, a free-wheeling diode and a transistor, wherein the positive output of said second source is connected to the anode of the free-wheeling diode and, through said chain of diodes, to the cathode of the zener diode and the collector of the transistor, the base of which is connected to the control unit, wherein the cathode of the free-wheeling diode is connected to the positive output of the welding current source, and the negative output of said second source is connected to the anode of the zener diode, the emitter of the transistor, the corresponding output of the control unit and the negative output of the welding current source.

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