RU2649351C1 - Method of mechanized deposition welding by the combination of arcs - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention can be used for arc mechanized welding in an inert gas environment by a combination of arcs of direct and indirect action. Non-melting electrode is connected to the negative pole of the first welding power source, and the product to its positive pole. Arc of the direct action is ignited between said electrode and the product, into which the first melting electrode is continuously fed. Arc of indirect action is ignited between the non-consumable and the consumable electrodes. In the arc of direct action, a second melting electrode of another chemical composition is continuously fed. Provide continuous burning of the arc of direct action in pulsating mode with the supply of current pulses of a greater or lesser magnitude and periodic alternate ignition and extinction of the mentioned arcs of indirect action. During the delivery of a pulse of a larger arc current of direct action, the arc of indirect action is extinguished, and during the period of a smaller current pulse one of the arcs of indirect action is ignited.

EFFECT: method ensures the stability of the process due to the minimal magnetic interaction of the arcs of direct and indirect action.

3 cl, 4 dwg, 2 tbl

Description

The invention relates to the field of welding and can be used in mechanical engineering for surfacing layers with special properties and welding difficult to weld steels and alloys.

There is a method of direct arc welding in inert gases between a non-consumable electrode and a workpiece with filler wire feeding into the arc zone (see I. A. Gedovius, V. M. Shmakov. “Welding of new materials in the environment of protective gases”, Kuibyshev, 1969. - 111 p., S. 5, Fig. 1).

The disadvantages of this method include low productivity and stability of the melting speed of the electrode wire. This is due to the fact that the wire is heated only by convection and radiation from the arc column; therefore, random changes in the position of the wire relative to the arc column lead to a significant change in its melting rate.

A known method of mechanized plasma surfacing in an argon medium by a combination of direct and indirect arcs, through which a negative pole of a welding power source is connected to a non-consumable electrode, and a positive pole is used to its product, a melting electrode is used, connected to the positive pole of the power source through ballast resistance, the arc is ignited direct action of direct polarity between the non-consumable electrode and the product; and an indirect arc between the non-consumable and the consumable electrode.

The method can be used for a free welding arc. Ballast resistance provides power to the second arc from a single power source, similar to powering arcs from multi-post power sources (see the article by I.E. Taver, M.Kh. Shorshorov "Welding steel with a double plasma jet", Welding production, 1971, No. 10, S. 26-28). This method is adopted as a prototype.

The disadvantage of this welding method is the strong interaction of the intrinsic magnetic fields of the arcs, leading to instability of the spatial position of the arcs and transfer of the electrode metal into the weld pool, which leads to large spatter of the electrode metal and instability of the size of the deposited bead. The use of ballast resistance to power an indirect arc does not ensure arc stability in all modes, since an arc with a consumable electrode burns steadily from a power source with a rigid current-voltage characteristic (CVC), and ballast resistance provides a falling CVC. All this makes it difficult to use an additional second indirect arc with a melting electrode to expand the technological capabilities of the process.

In the known method of mechanized surfacing with a combination of direct and indirect arcs in an inert gas medium, in which a negative pole of a welding power source is connected to a non-consumable electrode, and a positive pole is connected to the product and a direct-action arc is ignited between them, the melting electrode is connected to the positive pole of the second source power supply, the negative pole of which is connected to a non-consumable electrode, ignite an indirect arc between non-consumable and consumable electrodes, the last provide a continuous arc of direct action.

Unlike the prototype, the second electrode wire of a different chemical composition is continuously fed into the direct-acting arc, connecting it to the positive pole of the second power source, provide periodic burning of the direct-acting arc in a pulsating mode and periodic alternate ignition and suppression of indirect arcs between non-consumable and consumable electrodes moreover, during the flow of a large current of a direct-acting arc, the indirect arc is extinguished, and during the flow of a small current of a direct-acting arc they burn one of the arcs of indirect action, the duration of the large current flow in the direct-action arc on the product is set within 0.2 ... 0.5 with respect to the current flow cycle in it, and the minimum average value of the small current of the direct-action arc is chosen to ensure its stable burning .

The average current of the ripple current in a direct-acting arc current of indirect arcs is determined by the formula

where d _E is the diameter of the melting electrode, cm;

V _e - the required rate of melting of the electrode, cm / s;

ρ is the density of the consumable electrode, g / cm ³ ;

α _P is the coefficient of melting of the consumable electrode when welding by a direct-acting arc at reverse polarity at current I _SC .

The pulse currents of indirect arcs can be chosen equal.

The technical result of the proposed method is to ensure stable burning of a combination of three arcs by synchronizing the ripples of the direct current arc current and alternating pulses of indirect arcs from electrodes of different chemical composition and thereby creating the possibility of varying the chemical composition of the weld over a wide range by changing the parameters of indirect arcs and creating the possibility of choosing the optimal chemical composition of the weld metal, using an inherent combination of straight and the consecrated action of the established property that when the currents of arcs of indirect action change, the cross-sectional area of the penetration of the base metal practically does not change.

The force of interaction of the magnetic fields of the arc currents, according to Ampere's law, is proportional to the product of the arc currents. When a direct-acting arc operates in a pulsating mode, and indirect-acting arcs in a pulsed mode, the product of the average currents of direct and indirect-acting arcs during the pulsation period is always less than the product of their average values inherent to the action of the arcs in the stationary mode. The minimum current requirement for a direct-acting arc is due to the need to ensure its stable burning.

The determination of the average currents of the currents of indirect arcs depending on the required melting rate of each electrode wire provides for the regulation of the chemical composition of the deposited metal and weld over a wide range of various alloying elements contained in both wires, and only in one of them.

The difference in currents in the wires during pulses provides even greater possibilities for controlling the chemical composition of the deposited metal, compared with the same currents.

The choice of currents of indirect arcs equal to simplifies the design of an electrical circuit for implementing the method.

In FIG. 1 shows a diagram of the implementation of the method, FIG. 2 - cyclograms of currents in arcs of direct and indirect action, FIG. 3 - dependences of the coefficient of fusion of the electrode wire on the arc current of reverse polarity, in FIG. 4 - current-voltage characteristics of the arc and the power source.

In FIG. 1 presents a diagram of the implementation of the proposed welding method.

An inert argon gas is supplied to the welding torch 1. A non-consumable tungsten electrode is placed in the burner 2. An direct-acting arc 4 from the welding DC power source 5 burns between the electrode 2 and the product 3. The negative pole of source 5 is connected to the non-consumable electrode 2. The positive pole of power source 5 has two outputs with conductors connected to product 3 through electronic keys 6 and 7.

The electronic key 6 provides the inclusion of a small ripple current of a direct arc arc, and the electronic key 7 - a large ripple current. Electronic keys 6 and 7 are controlled using a special control circuit. During the activation period of the electronic key 6, the electronic key 7 is disabled and vice versa. Electronic keys 6 and 7 using an electronic circuit allow you to adjust in the period the duration of the flow of small I _MP and large I _BP pulsation currents in an arc of direct action 4.

In a direct-acting arc 4, a melting electrode 8 is supplied with a constant speed V _E1 . The electrode 8 is connected to the positive pole of the second DC power supply 9. The negative pole of the power supply 9 is connected to a non-consumable electrode 2. An indirect arc 10 can burn between the consumable electrode 8 and the non-consumable electrode 2. In the conductor connecting the electrode 8 to the power source 9, an electronic key 11 is installed, which ignites and extinguishes the indirect arc 10 and controls the duration of the current flow in the indirect arc 10. The duration of the current flow in an indirect arc of 10 t _K1 is equal to the time of flow of a small current in an arc of direct action t _MP .

A second melting electrode 12 with a different chemical composition of the alloying elements than in the first electrode 8, with a constant speed V _E2, is also fed into the direct-acting arc 4. The consumable electrode 12 is also connected to the positive pole of the second DC power source 9. The negative pole of the power source 9 is connected to the non-consumable electrode 2. Between the consumable electrode 12 and the non-consumable electrode 2, a second indirect arc 13 can burn. In the conductor connecting the melting electrode 12 to the power source 9, an electronic key 14 is installed, which ignites and extinguishes the indirect arc 13 and controls the duration of the current flow in the indirect arc 13. The duration of the current flow in an indirect arc 13 t _{K2 is} also equal to the flow time of a small current in an arc of direct action t _MP .

Electronic switches 11 and 14 ignite and extinguish indirect arcs 10 and 13 periodically and alternately during the flow of a small ripple current in a direct arc 4. The duration of the currents in each of the indirect arcs 10 and 13 is equal to the duration of the small current in a direct arc 4. Accordingly, it can vary within 0.8 ... 0.5 of the current flow in a direct-acting arc. Electronic keys are controlled using a special electronic control circuit. Stable ignition of indirect arcs 10 and 13 is ensured by the continuous supply of melting electrodes into the column of a continuously burning direct-acting arc 4 due to a sufficiently high frequency of current pulses.

In FIG. 2 shows the cyclograms of currents of arcs of direct and indirect action. The cyclograms represent the dependences of the change in the arc currents on time t. The shape of the ripple is rectangular, that is, during the ripple, the current does not change. Dependence 1 for a direct-acting arc, in which the current flows continuously, but with ripples. The entire period of the flow of direct current arc is designated t _C. In FIG. 1 shows two periods of pulsations of a direct-acting arc. The flow time of a small current of a direct-acting arc I _MP is t _MP , and the flow time of a large current of a direct-acting arc I _BP is t _BP . High current mainly provides penetration of the product. Low current mainly provides stable ignition of arcs of indirect action. The ratio of the flow time of a small current of a direct-acting arc with respect to the duration of the cycle should be chosen within t _MP / t _C = 0.5 ... 0.8, and large, respectively, t _BP / t _C = 0.5 ... 0.2. This allows you to further control the average direct arc arc current and, therefore, to adjust the penetration area of the base metal, depending on what proportion of the participation of the base metal in the weld metal is required. In addition, this makes it possible, while maintaining the average current, to regulate the arc pressure on the weld pool during periods of current ripple.

Dependence 2 in FIG. 2 is a current flow diagram of one of the indirect arcs between the consumable and non-consumable electrodes. The flow time of the current of the first arc I _1K indirect action is t _1K . The flow time of a small current in a direct-acting arc in FIG. 2 is equal to the current flow time in the first indirect arc t _MP = t _1K . Current I _1K provides the required melting rate of the first electrode wire. Due to this system of current flow to a minimum, the interaction of the magnetic fields of arcs of direct and indirect action is reduced.

The ratio of the current flow time in an indirect arc with respect to the duration of the pulsation cycle of a direct arc should be selected in the range t _K1 = (0.5 ... 0.8) t _C. This will allow, in addition to the indirect arc current, to regulate the cross-sectional area of the deposited metal, depending on what value of the deposited metal fraction in the weld metal is required to be obtained. Accordingly, the energization time duration of the arc in the direct action in this period will _Megapixel t = (0,5 ... 0,2) t _C.

The effective value of the unidirectional arc current with any pulse shape is its average current, since the arc voltage is practically independent of the current.

The average, over two periods of current ripple in a direct-acting arc, the current of the first indirect-action arc with a consumable electrode with a rectangular shape of the current pulse can be determined by the formula

where I _1K - the value of the pulse current of the first arc of indirect action during its course in the cycle;

t _1K - the time flow of the current pulse of the first indirect arc in one period.

Time t _C is the cycle time of the arc of direct action.

Coefficient 2 in the denominator of formula (1) takes into account that the burning of arcs of indirect action alternates and one arc burns once during two periods of ripple of the current of the arc of direct action.

Dependence 3 in FIG. 2 is a current flow diagram of a second indirect arc between a consumable and non-consumable electrodes. The entire period of the current flow in the direct-acting arc is designated t _C. The current flow time of the second indirect arc I _2K is t _2K . The flow time of a small current in a direct-acting arc in FIG. 2 is equal to the current flow time in the second indirect arc in FIG. 4 t _MP = t _2K . Current I _2K provides the required melting rate of the second electrode wire. Due to this system of current flow to a minimum, the interaction of the magnetic fields of arcs of direct and indirect action is reduced. In the general case, the currents of indirect arcs differ from each other I _1K = I _2K , and the current flow in these arcs is always the same t _1K = t _2K = t _MP .

Therefore, the ratio of the current flow time in the second indirect arc with respect to the duration is the same as for the first indirect arc. This allows, in addition to the indirect arc current, to regulate the cross-sectional area of the deposited metal, depending on what value of the deposited metal fraction in the weld metal is required to be obtained.

The average current of the second indirect arc with a melting electrode with a rectangular shape of current pulses per cycle can be determined by the formula

where I _2K is the value of the current of the second indirect arc during the pulse period;

t _2K is the current flow time of the second indirect arc (pulse time).

Time t _C is the cycle time for ripple current in a direct arc.

Coefficient 2 in the denominator of formula (2) takes into account that the burning of arcs of indirect action alternates and one arc burns once during two periods of ripple of the current of the arc of direct action.

The content of any chemical element in the seam is determined by the well-known formula

where С _Э ^О is the content of a given chemical element in the base metal,%;

ψ _О - share of the base metal in the weld metal;

С _Э ^Э - content of this chemical element in the deposited metal,%.

The share of the base metal in the weld metal ψ _О is determined by the formula

where F _About - the cross-sectional area of the penetration of the base metal, cm ² ;

F _H - the cross-sectional area of the weld metal, cm ² .

The cross-sectional area of the deposited metal during surfacing with two electrode wires can be calculated by the formula

where P ₁ and P ₂ - deposition performance, respectively, of the front and rear electrodes, g / s;

ρ is the density of the deposited metal, g / cm ³ ;

V _C - welding speed, cm / s.

In formula (5), it is assumed that the metal densities of the electrodes are equal.

The deposition performance of each of the electrodes can be calculated by the formula

where α _N is the surfacing coefficient, g / (A⋅h);

I - arc current, A.

The deposition coefficient α _N depends on the diameter of the electrode, arc current, electrode stick-out, and arc polarity.

The deposition coefficient is uniquely related to the melting rate of the electrode

where ψ _P is the coefficient of electrode loss due to burning and spraying;

V _e - the melting rate of the electrode, cm / s;

j is the current density in the cross section of the electrode, A / cm ² .

The electrode surfacing coefficient α _H is determined experimentally through the melting coefficient and is given in the specialized literature.

Thus, knowing the content of the chemical element in the electrodes, using formulas (3-7), it is possible to calculate its content in the weld if the cross-sectional area of the base metal F _{O is} known. In the proposed method, it is determined experimentally when surfacing by a known method with a direct-acting arc at a given current equal to the average current of a pulsating direct-acting arc, or theoretically by using a calculated heat distribution scheme during welding.

Since in the proposed method the electrode wires are connected to the positive pole of the power source and are anodes, in the proposed method, when using V _e in formula (7), it is necessary to take its values for the arc of direct action of reverse polarity.

To ensure the required fraction of deposited metal of each of the electrodes in the weld metal at a given average direct arc current and, accordingly, the cross-sectional area of the penetration of the base metal, a certain productivity of melting of each consumable electrode is required, which is determined by its melting speed V _E.

It follows that the required value of the average welding current of each indirect arc can be determined by the formula

where d _E is the diameter of the melting electrode, cm;

V _e - the required rate of melting of the electrode, cm / s;

α _P is the melting coefficient of the consumable electrode when welding by a direct-acting arc at reverse polarity at the arc current I _D = I _C.

Thus, according to the dependences of the melting coefficient in a direct-acting arc of reverse polarity and the required melting rates of the electrodes, it is possible to determine the necessary average currents of indirectly acting arcs in a pulsed mode by the proposed method and, therefore, the values of currents during the pulse period.

Knowing the average current of an indirect arc determined by formula (8), using formula (2), it is possible to calculate its required current in a pulse I _1K or I _2K .

The average current of a direct-acting arc with a non-consumable electrode with a rectangular shape of current ripples during the ripple period can be determined by the formula

where I _MP - the average value of a small current arc direct action during its course in the cycle;

t _MP - the time of flow of a small current arc direct action;

I _BP - the average value of a large arc current of direct action during its course in the cycle;

t _PSU - the flow time of a large current arc direct action.

Time t _MP + t _BP = t _C is the cycle time for a direct-acting arc.

The duration of the current flow of pulses of indirect arcs is equal to the time of flow of a small current of a direct arc

t = t _{1K 2K Megapixel} = t = (0,5 ... 0,8) t _C.

Regulation of the flow time of the currents of arcs of direct and indirect action is necessary to create additional technological capabilities associated with the choice of the optimal transfer of drops of electrode metal and the pressure of the arcs on the weld pool. It is impractical to set the direct arc current flow time less than 0.2 cycle time due to a possible violation of the uniformity of the melting rate of the melting electrodes.

The average direct arc current for the period determines the cross-sectional area of the penetration of the base metal. By changing the ratio of the average currents of arcs of direct and indirect action, it is possible to regulate the proportion of the participation of the base metal in the weld metal.

In FIG. Figure 3 shows the dependences of the melting coefficient α _{P of the} aluminum electrode wire on the arc current of the opposite polarity according to published data. Curve 1 represents the dependence for the wire brand SvAMts with a diameter of d _E = 1.6 mm, curve 2 for wire SvAMg6 with a diameter of d _E = 2.0 mm. Curve 1 for a smaller diameter electrode is located above curve 2 for a larger diameter. Therefore, at the same currents, the melting coefficient and the melting performance of a smaller diameter electrode wire are greater. Similar dependences hold for steel wires in an arc of reverse polarity in inert gases.

As a result of the studies, it was found that the cross-sectional area of the base metal is practically independent of the power transmitted to the weld pool by liquid electrode metal, but depends only on the average direct arc current. This is due to the fact that the power absorbed by the liquid metal of the electrodes is transferred to the weld pool and through it has very little effect on the penetration of the product. Therefore, when using this method, it is easy to determine the content of any alloying element in the seam with known composition of electrode wires, base metal and arc modes. By changing the currents of arcs of indirect action, it is possible to regulate the chemical composition of the weld over a wide range, since the penetration cross section of the base metal practically does not change.

Due to the regulation of the performance of melting and surfacing of wires with their various chemical composition, it is possible to obtain a wide range of alloying elements in the weld metal and weld metal. The performance of the melting and surfacing of each wire can be adjusted separately due to the average current of indirect arcs for two periods of pulsation of the direct arc, the duration of the current flow of these arcs, the diameter of the electrode wires, the release of electrode wires. The participation of the main (or electrode) metal in the weld metal can be regulated practically independently of the current of indirect arcs by the average current of the direct arc. This provides high technological flexibility of the welding method. The need to create new wires can almost completely disappear, since the necessary composition of the seam can be calculated and obtained using known wires.

In FIG. Figure 4 shows the dependences of the current-voltage characteristics of the arc and the power source. Curve 1 represents the steeply falling current-voltage characteristic of the power source, curve 2 represents the current-voltage characteristic of the arc with a non-consumable tungsten electrode, curve 3 shows the current-voltage characteristic of the power source, which ensures minimal welding currents. Curve 2 has a falling section, a minimum of voltage, and an increasing section. Curve 1 and curve 2 intersect at two points B and D. At these points, an arc with a non-consumable electrode may exist. In accordance with the theory of the welding arc, point G is an unstable operating point of the system, since the stability condition is not fulfilled in it and the arc goes out with small deviations of the current. On the contrary, point B is the operating point of the system at which the stability condition is satisfied and with small deviations of the arc current, it passes into a new stable state. The point of intersection of the current-voltage characteristic of arc 2 with the current-voltage characteristic of arc 3 at point B gives the minimum current value, but at which stable burning of the arc with a non-consumable electrode is not provided. This current cannot be used as small when choosing a pulsating mode of combustion of a direct-acting arc between a non-consumable electrode and the product according to the proposed method. On the contrary, at the working point A of the intersection of curves 3 and 2, stable arc burning is ensured. Therefore, the current I _MP for this point can serve as a small ripple current in a direct-acting arc.

Example.

Surfacing was carried out according to the proposed method with electrode wires in accordance with GOST 10543-98: Np-20X14 with a diameter of d _E = 1.6 mm and Np-G13A with a diameter of d _E = 1.2 mm onto a plate of steel 20 with a thickness of δ = 10 mm.

The content of alloying elements in wires and base metal as a percentage according to the certificates is given in table 1.

The deposition rate was V _C = 0.5 cm / s. A direct-acting arc between a non-consumable electrode with a diameter d _e = 3 mm of the welding torch and the product burned in an argon atmosphere. The argon flow rate was G = 10 l / min. The direct-acting arc was powered by a VDU-306 DC welding power source. Indirect arcs were fed from another FORSAGE-500 power source. The electric circuit provided the following parameters of ripples of the direct current arc current: a large ripple current of a rectangular shape I _BP = 300 A, its flow time 0.01 s, a small ripple current of a rectangular shape I _MP = 50 A, its flow time 0.01 s. The ripple period of the direct-action arc was t _C = 0.02 s, the ripple frequency f = 50 Hz. Average direct arc welding current

I _SP = (3000.01 + 500.01) / (0.01 + 0.01) = 175 A.

Previously, during conventional argon-arc surfacing with a direct-acting arc from the same power source at the arc current I _D = I _SP = 175 A, surfacing was performed without filler wire with a welding speed V _C = 0.5 cm / s. The cross-sectional area was determined from the macro section penetration of the base metal F _O = 0.4 cm ² .

The melting rate of the electrode wires according to the proposed method was selected from the condition of equal areas of the deposited metal from each of the wires F _H1 = F _H2 = 0.1 cm ² . To obtain such cross-sectional areas and welding speeds V _C = 0.5 cm / s, the melting and wire feed speeds should be respectively for Np-20X14 V _E1 = 2.5 cm / s and for Np-G13A V V _E2 = 4 , 4 cm / s. In this case, the electrode metal loss coefficient was taken for both electrode wires ψ _P = 0.05.

Through experiments with a direct-current direct-current arc of reverse polarity, it was established that for this purpose arc currents are necessary for the wire Np-20X14 I _C1 = 120 A and for the wire Np-G13A I _C2 = 110A. Therefore, the average values of the currents of pulses of arcs of indirect action for the period of the cycle of the arc of direct action should be equal to the obtained values of the arc of direct action.

The duration of the rectangular current pulses for each of the indirect arcs will be equal to the duration of the small current flow of the indirect arc and be t _K1 = t _K2 = t _MP = 0.01 s.

Using the formula (2), we determine the value of the pulse current of the indirect arc I _1K from the wire Np-20X14

I _1K = I _1C ⋅2t _C / t _2K = 120⋅2⋅0.02 / 0.01 = 480 A.

Similarly, determine the value for the wire Np-G13A

I _2K = I _2C ⋅2t _C / t _2K = 110⋅2⋅0.02 / 0.01 = 440 A.

The content of chemical elements in the weld metal and weld was calculated. Since the areas of deposited metal from each electrode wire are equal, the deposition productivity and the content of any element will be equal to half the sum of its content in each wire. The content of elements in the weld at a known content in the weld metal was calculated by the formula (3) at ψ _О = 0.67. The calculation results in% are shown in table 2.

Selecting various wires and combustion modes of indirect arcs, you can get almost any required chemical composition of the weld metal and weld.

When the axes of the columns of arcs of direct and indirect action are located at an angle to each other according to Ampere’s law, the force of mutual influence of the arcs will be proportional to the product of the currents of these arcs.

During the flow of the larger of the currents of arcs of indirect action, the interaction force of the pillars of arcs is proportional to the product of currents

F ₁ = k⋅480⋅50 = k⋅24000 A ² ,

where k is the coefficient of proportionality, the same for any currents.

When welding by a known method, the direct current arc current would be 175 A, and the indirect arc currents would be reduced by 2 times

F ₂ = k⋅240⋅175 = k⋅42000A ² .

The last work is 1.75 times the maximum of the two works by the proposed method.

The method can be implemented using semi-automatic machines and machines for mechanized and automatic welding in inert gases produced by the industry with filler wire feeding together with used welding power sources. Such installations need to be supplemented with devices for switching currents from the positive poles of DC power supplies with the corresponding electronic control circuit. The latter does not present a problem for the current level of development of electronic and microprocessor technology. Therefore, the method has industrial applicability.

Claims (8)

1. A method of mechanized surfacing of metal layers by a combination of direct and indirect arcs in an inert gas medium, comprising connecting a non-consumable electrode to the negative pole of the first welding power source, and the product to its positive pole, and ignition between the electrode and the direct-arc product, the first melting electrode, which is connected to the positive pole of the second power source, the negative pole of which is connected to cathode, and ignite an indirect arc between non-consumable and consumable electrodes, characterized in that a second melting electrode of a different chemical composition, connected to the positive pole of the second power source, is continuously fed into the direct-acting arc, while providing continuous burning of the direct-action arc in a pulsating mode with the supply of current pulses of a greater or lesser magnitude and periodic alternate ignition and suppression of the mentioned arcs of indirect action, and during the supply of imp The pulses of a larger current of a direct-acting arc are extinguished, and during the supply of a pulse of a smaller current, the arcs of direct action ignite one of the arcs of an indirect action, while the pulse duration of a larger current of a direct-acting arc is set within 0.2 ... 0.5 with respect to the total duration of both pulses of the current flow, and the minimum average value of a smaller pulse current of the direct arc arc is chosen from the condition of ensuring its stable combustion. 2. The method according to p. 1, characterized in that the average current of the arcs of indirect action is determined by the formula

, where d _E is the diameter of the melting electrode, cm; V _e - the melting rate of the electrode, cm / s; ρ is the density of the consumable electrode, g / cm ³ ; α _P is the melting coefficient of the consumable electrode when welding by a direct-action arc on the reverse polarity at current I _SC . 3. The method according to p. 1, characterized in that the currents of both arcs of indirect action are chosen equal.

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