RU2648618C1 - Method of automatic welding by the combination of arcs - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to the field of welding production. Method includes igniting an arc of direct action between the non-consumable electrode and the article and igniting an arc of indirect action between two meltable electrodes that are continuously fed into the welding zone. In this case, the arc of indirect action is placed behind the arc of direct action with respect to the direction of its movement within the weld pool. Said arcs are supplied with periodic pulsation of the magnitude of the currents between the low and high currents, in the way that during the course of a large current of an arc of direct action, a small current flows in an arc of indirect action, and during a period of a small arc current of a direct action in an arc of indirect action, a large current flows.

EFFECT: use of the invention provides an increase in productivity and quality of welding.

6 cl, 6 dwg, 3 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., P. 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 automatic plasma welding in an argon medium by a combination of direct and indirect arcs, by 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 via ballast, ignite the arc 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 , p. 26-28). This method is adopted as a prototype.

The disadvantages of this welding method include the low productivity of surfacing and the limited ability to control the chemical composition of the weld, due to the use of one electrode wire and the strong interaction of the intrinsic magnetic fields of the arcs, leading to instability of their spatial position and transfer of electrode metal into the weld pool, which leads to large spatter and loss of electrode metal and instability of the size of the deposited roller. 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.

In the known method of automatic welding by a combination of direct and indirect arcs in an inert gas medium, in which the negative pole of the welding power source is connected to the non-consumable electrode and the positive pole is connected to the product and the direct action arc is ignited between them, the melting electrode is connected to the pole of the second power source , light an indirect arc from it, feeding it continuously into the welding zone.

In contrast to the prototype, the second electrode wire is continuously fed into the welding zone, connecting it to the other pole of the second power source, an indirect arc between the melting electrodes is ignited, positioning it behind the direct acting arc with respect to the direction of the welding speed within the length of the weld pool formed on the product with an arc of direct action, provide pulsation of the currents of arcs of direct and indirect action, and during the flow of a large current of the arc of direct action, in the indirect arc flows m high current, and during the flow of a small current of a direct-acting arc, a large current flows in an indirect-arc, the duration of a large current in a direct-acting arc is set on the product within 0.2 ... 0.8 with respect to the current flow in it, moreover minimum average values of small currents of arcs of direct and indirect action are chosen to ensure their stable combustion.

The diameters of the electrodes of the indirect arc can be selected different.

Departures of electrodes of an indirect arc can be selected different.

The chemical compositions of the electrode wires can be selected different.

Indirect arc electrodes can be connected to a DC power source.

Indirect arc electrodes can be connected to an AC power source.

The technical result of the proposed method is to increase the productivity of surfacing while improving the stability of the welding process by reducing the magnetic interaction of the arcs. The increase in productivity is provided by the use of a second consumable electrode in an indirect arc. Reducing the magnetic interaction of the arcs is ensured both by removing the arcs from each other to a distance to the length of the weld pool, and due to the pulsating nature of the arc currents.

The force of interaction of the magnetic fields of arcs according to Ampere's law, as two conductors, is inversely proportional to the distance between them.

The force of interaction of the magnetic fields of the arc currents, also according to Ampere's law, is proportional to the product of the arc currents. When a direct action arc and an indirect action arc are pulsed according to the proposed algorithm, the product of the average currents of the direct and indirect action 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 location of the melting electrodes of the indirect arc behind the non-consumable electrode of the direct arc relative to the direction of the welding speed within the length of the weld pool ensures that droplets of the electrode metal enter the weld pool and the formation of a single seam in which the base and electrode metals are mixed.

The limitation of the minimum average values of small currents of arcs of direct and indirect action is aimed at ensuring their stable combustion in the "arc-power source" system.

Determining the range of the ratio of the ripple time in arcs to the period provides additional technological capabilities of the arcs, for example, with insufficient power of the welding power sources.

The choice of different diameters of the melting electrodes expands the technological capabilities of the method in relation to the surfacing performance of each of the electrodes.

The choice of the flights of the melting electrodes with various additionally expands the technological capabilities of the method with respect to the surfacing performance of each of the electrodes.

The choice of various chemical compositions of the melting electrodes expands the technological capabilities of regulating the chemical composition of the deposited metal by using various combinations of well-known wire grades by adjusting the direct current arc, the diameter and the electrode extension.

In FIG. 1 shows a diagram of the implementation of the method, FIG. 2 is a current flow diagram in a direct-acting arc, in FIG. 3 is a current flow diagram in an indirect arc, FIG. 4 - current-voltage characteristics of the arc and the power source, in FIG. 5 - dependences of the coefficient of fusion of electrode wires, in FIG. 6 - dependence of the content of alloying elements in the weld metal on the arc current of indirect action.

In FIG. 1 presents a diagram of the implementation of the proposed welding method. Argon is supplied to the nozzle of the welding torch 1. A non-consumable tungsten electrode is placed in the burner 1. Between the electrode 2 and two parts of the product 3, a direct-acting arc 4 from the welding DC power source 5 burns. The negative pole of source 5 is connected to the non-consumable electrode 2. The positive pole of power supply 5 has two outputs with conductors connected to the product 3 through electronic keys 6 and 7. The welding torch 1 moves along the product 3 with a welding speed V _C. Welding pool 8 arises from the direct-acting arc. Behind the direct-acting welding arc 4 with respect to the direction of the welding speed, melting electrodes 9 and 10 are located within the weld pool 8. They are connected to the second welding power source of direct or alternating current 11. Between them, it continuously burns a pulsating arc of indirect action 12. The consumable electrodes 9 and 10 can have different diameters and lengths, different chemical composition. In the General case, they are melted and served with different speeds V _E1 and V _E2 independent feed mechanisms. Between the axis of the non-consumable electrode 2 and the plane in which the consumable electrodes 9 and 10 are located, a distance Δ that lies within the weld pool. Drops of electrode metal from electrodes 9 and 10 fall into the weld pool 8.

The device of the welding source 5 provides two modes of supply of the arc of direct action: with high and low currents. 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 ripple currents in an arc of direct action.

The device of the welding source 11 also provides two modes of power supply of the arc of indirect action: with high and low currents. In the conductors connecting the melting electrodes 9 and 10 with the power source 11, electronic keys 13 and 14 are installed, which provide ripple current of the indirect arc 12 and regulate the duration of the flow of large and small currents in the indirect arc 12. The duration of a large current flow in an indirect arc of 12 t _{BC is} also equal to the time of a small current flow in a direct action arc of 4 t _MP . Accordingly, it can vary within 0.8 ... 0.2 of the current flow in a direct-acting arc.

Electronic keys 13 and 14 periodically switch the indirect arc 12 from a small current to a large one depending on the magnitude of the flow of ripple current in a direct-acting arc 4. Electronic keys are controlled using a special electronic control circuit. The stability of the indirect arc 12 is provided due to its continuous burning and supply of melting electrodes 9 and 10 with the speed of their melting.

In FIG. 2 shows a sequence diagram of the direct current arc current. The cycle diagram represents the dependence of the change in the arc current on time t. The shape of the current ripples is rectangular, that is, during one ripple the current does not change. The entire period of the flow of direct current arc is designated t _C. 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 _PSU is t _BP . High current mainly provides penetration of the product. A small current mainly supports stable arc burning. 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 = 0.2 ... 0.8, and large, respectively, t _BP / t _C = 0.8 ... 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.

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 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 value of a small current arc direct action during its course in the cycle;

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

I _BP - the 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 action of the average current on the penetration of the product in a pulsating mode is equivalent to the action of the direct current equal to it of an arc of direct polarity.

The relationship in FIG. 3 is a sequence diagram of an indirect arc current between melting electrodes. The flow time of a small arc current I _MK indirect action is equal to the flow time of a large arc current direct action t _BP . The flow time of a large arc current I _BK indirect action is equal to the flow time of a small arc current direct action t _MP . Current I _BK provides mainly the required rate of melting of the electrode wires. I _MK provides predominantly stable arc burning. Due to such a system of flow of currents of arcs of direct and indirect action, the interaction of magnetic fields of arcs is reduced to a minimum. Additionally, a decrease in the magnetic interaction of the arcs is provided due to their removal from each other in comparison with the known method.

The ratio of the ripple time of a small or large current in an indirect arc with respect to the duration of the ripple cycle of a direct arc should be selected in the range t = (0.2 ... 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 duration of the flow of large or small current in an arc of direct action in this period will be t = (0.8 ... 0.2) t _C.

The average, for a period, current of an indirect arc with a melting electrode with a rectangular shape of the current pulse can be determined by the formula

where I _MK - the value of a small arc current of an indirect action during its course in the cycle;

t _MK - the time of flow of a small current of an indirect arc in one period;

I _BC - the value of a large current of an indirect arc during its course in the cycle;

t _BC - time of the large current flow of an indirect arc in the period.

Time t _C is the cycle time of arcs of direct and indirect action.

The effect of the average current on the melting rate of the electrodes in a pulsating mode is equivalent to the action of an equal direct current in a stationary mode.

In FIG. Figure 4 shows the dependences of the current-voltage characteristics of the arc and the power source. Curve 1 represents the steeply dropping current-voltage characteristic of a power source for an arc with a non-consumable electrode, curve 2 represents the current-voltage characteristic of an arc with a non-consumable tungsten electrode, curve 3 shows a current-voltage characteristic of a power source that provides 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 current at this point corresponds to a large ripple current in the direct-acting arc I _PSU . The intersection point of the current-voltage characteristic of arc 2 with the current-voltage characteristic of source 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.

In FIG. 5 shows the dependences of the melting coefficient α _{P of the} aluminum electrode wire on the arc current of the opposite polarity according to the literature. Curve 1 represents the dependence for the wire brand Sv-AMts with a diameter of d _e = 1.6 mm, curve 2 for wire Sv-AMg6 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. The dependences α _P for direct polarity are characterized by a large angle of inclination with respect to the axis of the currents. This is due to the dependence of the electrode melting coefficient at zero outflow on the arc current.

The melting coefficient is related to the surfacing coefficient by the empirical ratio

where Ψ _П - loss coefficient for waste and spraying.

The surfacing performance for each of the melting electrodes can be calculated by the formula

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

I _SK - average arc current of indirect action, A.

In this case, the surfacing coefficient of each electrode will generally be different depending on the pole of the power source connected to the electrode.

From the graphs of FIG. 5 it follows that the diameter of the consumable electrode has a significant effect on the deposition coefficient and, therefore, on its productivity.

The literature provides a formula for the melting rate of a thin silicon-manganese electrode wire in an arc of reverse polarity in a protective gas. For the melting coefficient in g / (A⋅s), it takes the form

where ρ is the density of the electrode material, g / mm ³ ,

L - reach, mm;

J is the current density, A / mm ² .

Formula (5) shows a significant dependence of the fusion coefficient on the electrode overhang. A similar dependence takes place for an arc of direct polarity and an arc of alternating current. Therefore, by changing the reach of the melting electrode, it is possible to control the performance of the melting in the proposed method.

The choice of well-known brands of electrode wires of various chemical composition provides unlimited possibilities for obtaining and regulating the chemical composition of the weld.

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

- содержание данного химического элемента в основном металле, %;Where

- the content of this chemical element in the base metal,%;

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

- содержание данного химического элемента в наплавленном металле, %.

- the content of this chemical element in the weld 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 by an indirect arc can be calculated by the formula

where P ₁ and P ₂ - the performance of surfacing electrodes, g / s;

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

V _C - welding speed, cm / s.

In formula (8), it is assumed that the metal densities of the electrodes are equal.

The deposition coefficient α _N depends on the diameter of the electrode, arc current, electrode stick-out, current type or 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 deposition coefficient of electrodes an is determined experimentally through the melting coefficient and is given in the specialized literature, as shown in FIG. 5.

Thus, knowing the content of the chemical element in the electrodes, using formulas (3-9), 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, F _O can be determined experimentally by surfacing using a known method with a direct arc at a given current equal to the average current of a pulsating arc of direct action or theoretically by using an adequate design of the heat distribution during welding.

The melting rate of each electrode in cm / s can be determined by the formula

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

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

Thus, according to the dependences of the melting coefficient in the direct arc and the current of the indirect arc, it is possible to determine the melting rate of the electrodes of the indirect arc in a pulsating mode according to the proposed method, and, therefore, to calculate the chemical composition of the deposited metal and weld.

In FIG. 6 shows the dependences of the content of alloying elements of manganese and chromium on the indirect current of the indirect arc for Sv-AMts and Sv-AMg6 wires with the diameters indicated for FIG. 5. Curve 1 represents the dependence for magnesium, and curve 2 for manganese. The wire of Sv-AMts was connected to the negative pole of the power source, and the wire of Sv-AMg6 was connected to the positive. The deposition coefficient for Sv-AMg wire was taken as α _N = 8 g / (Ah), and for the Sv-AMg6 wire, α _H = 7 g / (Ah). The manganese content in the wire Sv-AMts was taken 1%, and magnesium 0%. The magnesium content in the Sv-AMg6 wire was taken to be 6%, and the manganese content was 0%.

The content of elements in the weld metal С _{Н was} calculated by the formula

where C ₁ and C ₂ - respectively, the content of the element in the first and second wires,%;

P ₁ and P ₂ - the melting capacity of the wires, g / s

From the dependencies in FIG. Figure 6 shows that the content of each of the elements in the deposited metal is extremely weakly dependent on the arc current of an indirect action. The difference takes place only in the third decimal place. This is because the electrode surfacing coefficients are usually quite close, the indirect arc current is the same for each of the electrodes and the melting performance is proportional to the current and deposition coefficient. At the same time, such a weak dependence makes it possible to control the content of the same elements in the weld over a wide range, since the cross section of the deposited metal and weld varies, and the cross section of the base metal remains almost constant. In accordance with formula (7), the proportion of the participation of the base metal in the weld and the content of alloying elements in accordance with formula (6) changes significantly. Thus, in the proposed method provides the possibility of significant separate regulation of the chemical composition of the weld due to the parameters of arcs of direct and indirect action or a joint change in the parameters of these arcs. The necessary composition is easy to provide, since the penetration of the product is practically independent of the power transferred to the product by the electrode metal of an indirect arc.

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.

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 electrodes is transmitted to the weld pool and through it has a very small 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 varying the arc current of an indirect action, it is possible to widely control the chemical composition of the weld, 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 diameter of the electrode wires, the extension of the electrode wires, the pole of connection to the power source. The participation of the main (or electrode) metal in the weld metal can be regulated almost independently of the indirect arc current by the average direct-acting arc current. 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.

If, for example, 50 grades of welding wires of various chemical composition are known, then, according to the theory of combinations, from them 49–50 = 2450 combinations of two wires can be obtained. Given the difference in wire diameters, spikes and polarity of the electrodes, it is possible to provide almost any desired composition of the deposited metal and, accordingly, the weld, without creating new grades of wires, as is required when welding by a known method.

Example.

Surfacing was carried out according to the proposed method with welding electrode wires in accordance with GOST 10543-98: Np-20X14 with a diameter d _E = 1.6 mm and Np-G13A with a diameter d _E = l, 2 mm onto a steel plate 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. A small direct current arc was provided by installing it in one of the conductors connecting the power source to the shunt ballast. Turning on and off the ballast resistance was carried out using a special electronic circuit. The indirect arc was powered by two FORSAGE-500 power sources for mechanized welding with electrode wire feed mechanisms. To ensure a small current of the indirect arc, one power source was turned on, and to ensure a large current, two sources were turned on in parallel. Switching sources from one to two parallel was carried out using the same special electronic circuit.

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. The average welding current of a direct-acting arc according to the formula (1)

I _SP = (300⋅0.01 + 50⋅0.01) / (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 feeding with a welding speed V _C = 0.5 cm / s. The macro section determined the cross-sectional area of the penetration of the base metal F _O = 0.4 cm ² . The length of the weld pool behind the non-consumable electrode was ≈1.0 cm.

The average arc current of an indirect action was chosen I _SK = 150 A. The positive pole of the FORSAGE-500 power source was connected to the Np-20X14 wire, and the negative pole to the Np-G13A wire. Based on the dependences of the melting coefficient in a direct-acting arc, the melting coefficients of the electrodes and the deposition coefficients were determined. The loss factor for fumes and spatter was taken Ψ _P = 0.05. Received for Нп-20Х14 α _Н = 14 g / (А⋅ч), for Нп-Г13А = 15 g / (А⋅ч). The deposition rates are summarized in table 2.

The total area of the deposited metal for two wires F _HO = 0.31 cm ² , the participation of the base metal in the weld metal

ψ _О = F _О / (F _О + F _Н ) = 0.5 / (0.5 + 0.31) = 0.62.

The duration of the flow of a large rectangular current for an indirect arc will be equal to the duration of the flow of a small current of a direct arc and be t _K = t _MP = 0.01 s.

The value of a large current of an indirect arc must be selected. We took I _BK = 250 A. In this case, the small current of the indirect arc from formula (2)

I _SC = (I _MK ⋅t _MK + I _BK t _BK ) / t _C

150 = (I _MK ⋅ 0.01 + 250 ⋅ 0.01) / 0.02.

Hence I _MK = 50 A.

When implementing the method, an indirect arc was located at a distance of 0.7 cm behind the non-consumable electrode. In this case, drops of electrode metal fell into the weld pool. The result is a smooth weld bead with stable bulge and weld width.

The content of chemical elements in the weld metal and weld was calculated. The content of elements in the weld metal С _{Н was} calculated by the formula (11). P ₁ and P ₂ - the performance of the melting wires in g / s were taken from table 2.

The content of elements in the weld at a known content in the weld metal was calculated by the formula (3) at ψ _О = 0.62. The calculation results in% are shown in table 3.

In the seam received a significant content of manganese and chromium, which are almost only in one of the wires. The experimental determination of the content of manganese and chromium in the weld coincided with the calculated content with a relative accuracy of ± 5%.

The inverse problem can also be solved when, based on the required content of the main alloying elements in the seam, the content of these elements in the wires and the necessary welding parameters that will ensure the composition of the seam should be calculated. With the modern capabilities of computer technology, this problem can be solved by quickly sorting out the solution to the direct problem given in the example.

By selecting various well-known brands of wires and combustion modes of direct and indirect arcs, almost any desired chemical composition of the deposited metal and weld can be obtained.

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 a large current of an indirect arc, the interaction force of the columns of arcs is proportional to the product of currents

F ₁ = k⋅250⋅50 = k⋅12500 A ² ,

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

During the flow of a small current of an indirect arc, the interaction force of the columns of arcs is proportional to the product of currents

F ₁ = k 50 - 300 = k - 15,000 A ² .

The value is greater when a small current flows in an indirect arc. When surfacing by a known method, the magnetic interaction of the arcs will be proportional to the product of the average currents

F ₁ = k 150-175 = k⋅26500 A ² .

Thus, the strength of the magnetic interaction according to the proposed method, without taking into account the removal of the indirect arc from the direct arc, decreases by almost 1.8 times when a small current flows in an indirect arc and more than 2 times when a large current flows in an indirect arc .

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 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 (6)

1. A method of automatic welding with direct and indirect arcs in an inert gas medium, including ignition of a direct action arc between a non-consumable electrode and a workpiece and ignition of an indirect action arc from a consumable electrode, which is continuously supplied to the welding zone, characterized in that the welding zone is continuously fed the second melting electrode with the formation of an indirect arc between the melting electrodes located behind the direct arc in relation to the direction of its movement within the welding a bath formed on the product by a direct-acting arc, while the non-consumable electrode is connected to the negative pole of the first welding power source, the positive pole of which is connected to the product, and each of the melting electrodes is connected to the corresponding pole of the second welding power source, and the power of the arcs is direct and indirect carry out with periodic pulsation the magnitudes of the currents between small and large currents so that during the flow of a large current of a direct-acting arc, in a braid arc a small current flows, and during a small current flow of a direct-acting arc, a large current flows in an indirect-acting arc, while the duration of a large current flow in a direct-acting arc is set to 0.2 ... 0.8 with respect to the flow cycle in it, the value of the small current of the direct-acting arc is set from the condition for ensuring stable burning of the direct-acting arc, the value of the large current of the direct-acting arc is set from the condition of ensuring a given penetration of the product, the value of the small current of the indirect arc is determined from the condition of ensuring stable burning of the indirect arc, and the value of the large current of the indirect arc is determined from the condition of ensuring the specified melting speed of the melting electrodes. 2. The method according to p. 1, characterized in that use consumable electrodes with different diameters. 3. The method according to p. 1 or 2, characterized in that the departures of the melting electrodes are set different. 4. The method according to any one of paragraphs. 1-3, characterized in that they use melting electrodes with different chemical compositions. 5. The method according to any one of paragraphs. 1-4, characterized in that the melting electrodes are connected to a welding DC power source. 6. The method according to any one of paragraphs. 1-4, characterized in that the consumable electrodes are connected to a welding AC power source.

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