DD210227A1 - ARC WELDING METHOD AND WELDING SYSTEM FOR CARRYING OUT THIS METHOD - Google Patents

Abstract

The invention is preferably intended for automatic UP welding of thick-walled workpieces with a seam joint and can be used in mechanical engineering, in particular in energy and mechanical engineering. While the aim of the invention is to expand the field of application of automatic submerged arc welding, the object is to provide a method and welding system in which the choice of wire feed speed into the welding zone in accordance with a given pulsating state of the arc current ensures stable arc burning. This is achieved in terms of the method essentially in that the arc current pulsation is created by generating unipolar current pulses whose duration corresponds to the intervals for the wire feed into the welding zone. The feed rate of the wire is kept constant for a 0.7-0.9 time period of its feedrate equal time, then reduced to zero with a delay whose mean value is given by the expression alpha = 1.15-0.21d, where alpha is the Wire diameter is. The welding system for carrying out the method is shown in FIG.

Description

-Zf-

9 ^? QOC 7 Berlin, the S, 9, 82 - ^ > U - O / WP S 23 K / 237 820/7

60 472 26

Arc welding process and welding plant to carry out, this process

Field of application of the invention

The present invention is preferably provided for the automatic submerged arc welding thick-walled workpieces with a seam and can in any branch of mechanical engineering, in particular ± m energy and chemical engineering in the production of vessel and boiler bodies, collection containers, pipe parts u, 3 . Find application"

The method and equipment can be successfully used to make the root part of butt and corner seams by automatic UP welding with a wire of the same diameter as that used to fill the seam joint,

The invention is also intended for controlling arc current modulation in UP welding in standard welding apparatus with a voltage-dependent arc-independent electrode wire feed into the welding zone,

Characteristic of the known technical solutions

It is a welding method (SU-copyright 315531, Kl, 3 23 K 9/00) known in which a periodic change of the Sogenstroms and the arc voltage and their pulsation by a synchronous change in the speed of the cord wire feed into the welding zone and the voltage at the Excitation winding of the generator (welding power source) and in the circuit of the armature winding of the motor of the wire

- ·. Oi.! ι ^ ..''.- 'J' J \ L ^ ö tj

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T O O Γ

be ensured feed mechanism "I _n consequently occurs a synchronous change in the current and the Absorbed Absorbed voltage, modulated by a sawtooth waveform.

At the end of each pulse, the Bogsn voltage reaches a minimum value, so wirti a stable burning of the arc only secured if the pause time t _? between two pulses of arc burning, the time does not exceed a time t_ OjOS s. This limits the possibilities of controlling the energy characteristics of the process and the arc's ability to burn in, when one of the most important frequency characteristics - duty cycle

^x z

for a period - at t _? = 0 is practically not regulated,

In the realization of the known SchweiSverfhring within limits of an arc burning time of the current increase to a maximum value and the subsequent current drop only exponential / while the generation of pulses of other shapes, such as trapezoidal or rectangular shape, is not guaranteed »

In addition, the method can be realized only when using welding generators as Schweißstrotnquelle.

There is known an arc welding method (G3-PS 1 361 569 3 23 K 9/16, 3 23 P) in which the arc current pulsation is created by generating unipolar pulses of a given frequency.

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In the course of each interval of electrode wire feed, whose duration is set within limits η = 0.1 to 3.0 s, the absolute value of the feed rate of the wire remains constant constant*·

The pause time between the intervals of the wire feed is selected within a range of m = 0.1 to 1.0 s «

In the course of the entire S _c hweißvorganges the voltage at the output terminals of the welding power source remains constant and is not synchronized to geregalt current ripple.

3eira Welding with a melting electrode, especially in UP welding ', the value of the Sogens.trorn and the forward speed of the wire are functionally related, 3If a wire of 2 to 5 ram diameter is used, the dependence is ü = f (V) in the value range of the Sogenstrom from 300 to 700 A almost linearly, at the moment of the setting of the wire feed the Bogenstrom must fall with a relatively fast speed "while the trailing edge of the current impulse must be steeply * As a result of a slowed Sogenlösung since the moment of the When the wire feed is adjusted, however, the current at the trailing edge of the pulse will fall off a flat inclined line. In this case, the period of arc extinction will depend on the powder properties and the frequency of the current pulsation, the degree of overheating of the molten metal, the evaporation of the metal and of the slag components the amount of molten powder vo In addition, a shape distortion of the current

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pulses appear at the trailing edge thereof due to inertia of the electronic-mechanical wire feed system,

Thus, in the process of arc burning at the end of each pulse, the current drops slowly due to slowed arc quenching and the inertia of the wire feed drive , while the trailing edge line of the current pulse is inclined to the horizontal at a relatively acute angle the following negative consequences,

At the moment of the crystallization of the metal, at the end of each strorage pulse at the tail part of the sponge bath, a molten metal burr is formed with respect to the electrode, which then solidifies, because the bow pressure at the fall of the drop decreases sharply. As a result, the plane of symmetry of the seam is more uniform along its entire length Metaligrat which is of slag and the subsequent cleaning greatly deteriorated the outer seam quality, the separability "

- the frequency characteristics of the periodicity of the electrical

lead wire feed and the current pulsation differ greatly from the programmed, which leads to a deviation from the program, for energy characteristics of the Verschvveißvorganges. For example, the duty cycle S_ for the periods of pulsation of Sogenstroas will be greater than the duty cycle S for the intervals of the wire feed:

^s i ⁷ -7ΓΓΊΓ ~ = ^s

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where Sj - a duty cycle for the periods of pulsations of the Sogenstroms-,

S - a duty cycle for the intervals of the electrode wire feed ,

η - the duration of the interval for the electrode feed,

m - the pause time between the wire feed intervals ,

t _T - the pulse duration during soot burning,

t _o - the pause time between pulses during soot burning

describe*

Due to a considerable deviation of the shape of the strorage pod from the rectangular shape, S _T ? S, t _T > n, t ₂ < ra _# was · :: too. leading to an understanding of the arc welding and burn-in capability of the wire feed interval and the pauses m between operations corresponding thereto.

It is a welder welding together with consumable electrode in individual points (Nietschv ^ eißen) (s "book of O, I, Vainboiiii" automatic arc point welding ", publishing house" Mashinostroenie ", I960, S, 166-169, 174) known, the is connected to a sheet-fed power source and includes a welding head and an electrode carrier housed in the housing of the head. The wire feeding mechanism is provided with a welding torch and an electric drive motor. In the axis of symmetry of the wire feeding axis system is a guide nozzle on the housing

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fastened with a replaceable tip, while on the opposite housing wall a console with an electrode wire magazine is arranged. The welding system is equipped with a feed and control unit connected to the electric motor and with a control unit for the wire feed mode of operation with a control vibrator and sparking fan, which ensure that the motor supply circuit is switched on and off.

The welding head is set over the welding position. " The operator actuates the feeding and control section by pressing the start button simultaneously closing the welding circuit with the feeding source and the spark circuit of the electric motor of the wire feeding mechanism Wire to the workpiece, an arc is ignited, and the welding is completed. At the same time, the multivibrator and an electronic controller of the control unit start counting the given welding time. »After the wire feed interval has elapsed, the actuators open the feeding circuit of the wire feed robot's electric motor and the feeding circuit with the supply sources» Ois welding is over,

In this case, at the moment when the electric motor is switched off, the rotational movement of the drive roller is not stopped instantaneously, but it continues to turn by a certain angle, depending on the inertia of the drive. «

To trigger the next pulse of Sobrbrennung must

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7 OO ^ ¹ * 7

the surgeon presses the start button repeatedly »An uninterrupted change of the periods of soot burning in the automatic cycle is not guaranteed by the known system.

The known device ensures for each mode a default value of the period of arc burning and the regulation of a delay of the arc, d * h, its extinguishing time after the setting of the wire feed when switched Schweißst romkreis *

The well-known welding plant makes it possible to carry out the operating mode only in one cycle »The constructive design of the system does not allow to specify and regulate the pause time between the cycles of the soot burning and to control the electrodynamic behavior of the electric motor of the wire feed mechanism» As a result, no regulation the duration of the intervals for the wire feed and the pauses between them in the pulsating operation of the arc burning allows.

In addition, no regulation of the duration of the current drop and the Hinterfiankensteilheit of the current pulse is ensured. As a result, the control ability for the seam forming conditions is greatly deteriorated, which deteriorates the quality of milling, especially in the execution of the root portion of the butt and corner joints by edge preparation.

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Object of the invention

The present invention seeks to broaden the field of application of automatic submerged arc welding for the execution of root seams, the production of relatively thin-walled workpieces, the execution of butt joints at maximum air gaps.

Explanation of the essence of the invention

It is an object of the present invention to provide an arc welding method and apparatus for carrying out this method in which the choice of the advancing speed of the electrode wire in the welding zone in accordance with a predetermined pulsating state of the arc ensures a stable arc firing which allows the root seams of to get high quality.

The above object is achieved in that in the realizable by a consumable electrode arc welding method, consisting in that the pulsation of the arc current is created by generating unipolar Stroaiimpulsen with a predetermined pulse repetition frequency and pulse duration corresponding to the duration of time intervals, in the course of the Electrode wire is supplied to the welding zone, and alternating with breaks, in the course of which Elaktrodendrahtvorschub is set in the welding zone, according to the invention, the Stromifflpulses determining feed rate of the electrode wire for a 0.7 to o, 9 times the duration

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Interval for its feed constant time is kept constant and then reduced to zero with a delay whose mean is expressed by the expression:

CL β 1,15 - 0,21d

where d is the diameter of the electrode wire

In the welding operation control process, it is desirable to limit the delay value limit deviations from the delay average by a range of 0.64 - 4. Q - _T ^ - 1.7 ° .

The object is also achieved by the fact that in the welding plant for carrying out the LichtbogsnschwaiSverfahrenj which is connected to a Schweißstronsquelle and a welding head containing a mechanism enta feeding the electrode wire in the welding zone and an electric drive motor for the wire feed mechanism Riechanismus, a dining and control part of the electric motor, an electrode wire feed control unit whose input is connected to the output of the supply and control part of the electric motor and the outputs of which are connected to the electric motor, according to the invention, the wire feed mode control unit comprises a stabilized supply source , at whose output sine series connection of a control multiplexer with separately controlled '.Vertan the Strominipulsdauer. and the break time, a signal power amplifier, a control relay, at whose output a group of the inputs

VVP S 23 K / 237 S26 / 7 60 472 26

7 82 6 ⁷

connected to a control unit for the trailing edge steepness of the current pulse, at whose output a different group of the electric drive motor for the Elektrodendrahtvorschubmechanisinus umsteuernden contactless control elements is connected, wherein the outputs of the two groups of Elements connected to the electric motor »

Ä'usführunqsbeisoiel

The present invention will be explained in more detail below with reference to several embodiments. In the accompanying drawings:

Fig. 1: Cyclogram of the welding process with a pulsating arc according to the proposed arc welding method;

2 shows an overview circuit diagram of a welding system for carrying out the arc welding method;

3 shows a block diagram of a control unit for the operating mode for the electrode wire projection into the welding zone.

The realizable by a consumable electrode arc welding method is that the pulsation of the arc current is created by generating unipolar current pulses at a predetermined pulse repetition frequency. The duration t _T (Fig * 1) of each current iris becomes

Λ Λ S *? Λ Λ -, f-J

.α »W / UL ·. \ j /

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by the duration η (Figure la) of time intervals during which the electrode wire is fed to the welding zone. On an experimental occasion, the duration t, (Fig, Ib) of the 31-pulse trailing edge was determined in performing the welding on an apparatus equipped with an electrode wire feeding mechanism with an AC and DC electric drive. It was found that for a high quality weld forming with a UP weld with a wire of 1.5; 2.0; 3.0; 5.0 mm diameter, the required shape of the current pulse is ensured at the values of the duration t of the back trailing edge of 0.1 to 0.15 s.

Based on the manufacturing requirements, the duration η of the intervals for the electrode wire feed is taken from a range of η = 0.3 to 0.1 s * Since t-, = 0.1 to 0.15 s, in each pulse Time for the wire feed to the flywheel zone at a constant speed of 0.7 η to 0.9 η »

On the basis of technological experiments, for each value of the electrode wire diameter, a mean value V and a permissible maximum and minimum value V or "V

³ η max n mm

the Vorschubgeschvvindigkeit of the wire determined "Here, the lower limit value of the speed out a stable arc burning during the pause guarantee is set in the course of the wire feed rate in the welding zone and the duration of = 0.3 to 0.8 s is chosen within a range from m , The maximum velocity value is chosen to ensure stable arc burning for a recommended arc voltage as a function of wire diameter.

ή _f ~ λ f + ' r »· / Ö L · Ό /

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In the known value range of the wire feed rate and the known trailing edge duration t, of the current pulse, corresponding delay values were calculated for each value of the wire diameter according to the formulas:

V V V.

λ - ⁿ . ο ^max - ^ mm

max t__ min _ ^ _3x

determined "

By a graphical and analytical processing of the experimentally determined data an expression was obtained, which mathematically has a function:

α = f <d);

a = 1.15 - 0.2.1 d

describes where d = the wire diameter »

In the welding operation control process, the limit deviation values of the deceleration of their mean value are in a range of

0.64 0. <a _χ < 1.7 CL

set "

The following is a concrete example that confirms the possibility of realizing the proposed Lichtboger welding method *

example

It was a root seam in the execution of a rotatable butt weld connection of a tube billets, the dimensions

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O, 0042 m / s 0,036 m / s 0.4 S 0.5 S.

325 75 mm welded with a V-shaped seam joint tube part »Oa the filling of the seam joint is realized under powder with a wire of 3 mm diameter, a wire of the same diameter is used for the execution of the root seam. The parameters of the manufacturing process were the following:

Weld speed Wire feed speed Duration of the wire feed interval

break time

When welding with a 3 mm diameter wire, the mean delay is the same;

• & = L, 15 - 0,21d a 1,15 - 0,21. 3 = C, 52 m / s ² ,

while the limit of acceleration is in a range of

0.333 ^ CL _I 5 0.88.

Based on the inertia of the welding apparatus used was found that the duration t, the pulse trailing edge must be 0.1 s. The test shows that a- = 0.36, ie, the value of the delay is within acceptable limits »

The utilization of the welding method according to the invention in concrete operation allowed a root seam to be higher

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7 c

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To get quality.

Prior to the development and transfer of the inventive method to production, the same root seam was formed on similar workpieces in an arc hand welding because the use of automatic UP welding technology with a quiet stable burning arc is impossible due to the occurrence of blow-throughs In both cases, the welded joints on workpieces were made of low carbon steel (Sample 1) and on steel workpieces of pearlite class (Sample 2) of the following chemical composition: 0.14 % C, 0.33 % Mn, 0.3 % Si , 0 _f 18 % V, 1.15 % Cr, 0.26 % Mo formed.

The technical-economic values for forming a root seam of a butt joint 325 χ 40 mm are given below.

Ifd «technical-economic

., Codes ι i r «

HandschwelSung Automatic Sample 1 Sample 2 UP-Schvveißg "

with a pulsating arc sample 1 sample 2

Labor intensity f. the weld of the seam root · (h)

0.494

, 598

0.24

0.28

Seam cleaning after shaving by means of

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Grinding wheel (h) 0.0745 0.0745 Steel brush (h) 0.0153 0.0153 Air chisel (h) G, 03 0.03

Total labor intensity for the formation of a root seam (h) 0.5138 0.717S C, 2.4 0.28

Specific power consumption per 1 kg of molten metal (kWh) 10 10 4.5 4.5

It can be seen from the given data ₃ that the use of the arc welding method according to the invention allowed to increase the efficiency of the process by 2 to 2.5 times and to reduce the power consumption for the welding by a factor of 2; h *, the production of welding pieces has become more economical »

By controlling the frequency characteristics and maintaining an optimal form of current pulses, it became possible to

- To use the automatic UP welding with a wire of 3 tnm diameter and more to the formation of the root part of a series of butt and corner joints in the manufacture of vessels, pipe parts and other workpieces, which the need to exploit the

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Excludes arc welding for these seams, increases the profitability of the production and improves the quality of the weldments,

To eliminate burn-in and other defects in UP welding of works with a root gap of up to 1.5 mm and a seam thickness of up to 2 mm, using a 3 to 5 mm diameter wire,

to obtain a concave suture surface in the form of a meniscus _s which is of particular importance in the execution of root plies in welds with a conventional Nahtfuge and in the execution of compounds having a narrow Nahtfuge, d, h,., there will be a separation of a slag crust without Change in the chemical composition of the sweat powder significantly easier »

to reduce the number of layers needed to fill the joint when forming horizontal and corner seams,

to use the UP weld to produce relatively thin-walled workpieces of 100 mm diameter and less by preventing the flow of molten metal and slag compared to welding with a quiet arc,

To expand the field of application of the UP-welding in relation to the existing technology of its execution with constant values of electrical operating data.

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The arc welding method according to the invention is realized with the aid of a welding installation 1 (FIG. 2) which is connected to a welding power level 2 and encloses a welding head 3. The welding head 3 contains a mechanism 4 for feeding the electrode wire into the welding zone, an electric drive motor 5 for the electrode wire feed mechanism 4, a pressure and drive roller 6 Όζηt 7 ₄ a guide nozzle 8 with a replaceable tip 9 for the wire feed in the SchvveiS zone of workpieces 10 and a welding wire magazine 11 "to control the welding head 3 is the system 1 with a feed To ensure the work of a pulsating arc and the regulation of the frequency characteristics of the welding process, the system 1 is provided with a control unit 13 for the mode for Elektrodendrahtvorschub _# whose input to the supply and control part 12 and its output the electric motor 5 of the electrode wire feed trachea anisurator 4 is connected *

The control unit 13 (FIG. 3) for the solenoid wire feed mode includes a stabilized supply source 14 which includes a series arrangement of a rectifier 15, a smoothing filter 16 and a stabilizer 17. At the output of the stabilizer 17 is connected a series circuit of a control multivibrator IS separately regulated values of the current pulse duration and the pause time, a signal power amplifier 19, a control relay 20 and a control unit 21 for the Hinterfiankensteilheit a Stromimpuises laid. To the outputs of the control relay 20 and the control unit 21 groups of contactless Stellale-

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7

22 and _e 23 connected whose outputs are coupled to the electric motor 5, Oedes element 22 and 23 consists of gage-parallel connected thyristor «

sn.

To carry out the welding with a pulsating arc, the following operations are carried out beforehand: The welding head 3 (FIG. 2) is introduced and arranged above the sliding piece 10 at the beginning of the seam. Since the wire feed mechanism 4 is provided with an AC motor, a required screw feed rate is determined by means of its change wheels. By means of the control divider 17 (FIG. 3), the required duration of wire feed time intervals in the weld zone and pauses between them is set * Then the welding power source 2 (Fig. 2) is turned on, and the equipment 1 is ready for welding *

The welding system operates as follows: To move the workpiece 10 (for example for the rotation of pipe billets or for the horizontal movement of sheets) with a predetermined welding speed, a drive (not shown in FIG. 2) is actuated. If the welding head 3 is in contact with a movable vane mounted, it is moved. From the supply part 12, the voltage is supplied to the input of the stabilized supply source 14 (Fig. 3) of the wire feed operating unit 13 which via the mechanism 4 (Fig. 2) feeds the wire to the welding zone in accordance with the predetermined pulsating state of the wire feed Welding current concerned »At the moment of advancing the wire into the welding zone, it touches the workpiece 10, the welding circuit is closed and an arc is ignited» This is how it works

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the welding process with melting electrode during the pulsating arc.

The control unit 13 (Fig. 3) for the wire feed mode operates as follows: The supply voltage is supplied from the feed section 12 to the inputs of the non-contact control elements 22 and 23 and via the stabilized supply source 14 to the control multivibrator IS, amplifier 19, control relay 20 and control unit 21 supplied for the trailing edge steepness of Stromiapuises *

After the voltage supply, the multivibrator 13 provides square wave signals with a controllable current pulse duration and pause time. These pulses pass through the amplifier 19 to the relay 20, which controls the work of the elements 22 which supply the voltage to the electric motor at a set periodicity pulsating state of the electrode wire feed into the welding zone is made possible »

In accordance with the modes provided for the multivibrator 18, the relay 20 is in the on and off state over a predetermined time corresponding to the duration of the wire feed intervals and the pauses between them.

At the moment of Aoschaitens of the relay 20, the control unit 21 turns on the rear slope of the current pulse which reverses over the group of the non-contact actuating elements 23 the electric motor 5 for the duration of the predetermined period of time.

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Λ ***. I = Y ft »W /

20 -

The elements 18 j 19; 20; 22 thus ensure a predetermined duration of the intervals for the wire feed and the pauses between them. This allows the characteristics of the pulsating state of the Schev / eißstroms; the duty cycle for the period to regulate the frequency of the pulsation.

The elements 20; 21; 23 provide for a given inversion time during the break and for the trailing edge steepness of the current pulse *

Such an embodiment of the control unit 13 for the operating mode zus feed pressure feed allows to carry out the process with a controllable duration of the periods of arc combustion and the pauses between them and to control the pulse shape of the arc current.

This precludes current pulse shape distortion of the inertia of the electric motor 5 of the wire feed mechanism 4 and the arc extinguishing delay.

The present design of the welding equipment makes it possible to carry out the process of UP-welding with a melting electrode and a pulsating arc and to regulate the frequency characteristics of the process. As a result, it becomes increasingly possible to increase the manufacturing properties of the UP-welding: arc incombustibility, thermal Duty Cycle, Outer Seam Quality and Separation to Control and Control Slag Crust «This extends the range of application of the automatic UP weld to perform rooting.

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for producing relatively thin-walled workpieces, for performing butt joints at maximum air gaps.

Claims (1)

Inventive a sprue Si 1. LichtbogenschvveiSverf Ahren, which is realized by a consumable electrode, consisting in that the pulsation of the arc current is created by the generation of unipolar current pulses having a predetermined pulse repetition rate and pulse duration corresponding to the duration of time intervals, fed in the course of which the electrode wire of the Schweißzcne and alternating with pauses during which the electrode wire feed is set in the welding zone, characterized by the fact that the feeding current of the electrode wire determines the current pulse for a 0.7 to o, 9-fold interval of its feeding time held constant and then reduced to zero with a delay whose mean is expressed by the expression: CL = 1.15 - 0.21d where d is the diameter of the electrode wire » 2. The method according to item 1, characterized in that in the control process for the welding operation, the delay of the deviation from the mean value of the delay by a range of 0.64 α < ⁰ ^ ₁ <1.7CL are restricted, 3 · Safety system for carrying out the method according to WP S 23 K / 237 826/7 60 472 26 ? 37 8? 6 7 & m ***? * X ^ λ υ -. ? % ^ J * - 23 - Points 1 and 2 ', which is connected to a Schvveißstromquelle and includes a welding head, the an electrode wire feed mechanism and an electric drive motor for the Elektrodendrahtschubmechanismus, a feed and control part of the electric motor, an ingot for the wire feed mode, the input to the output of Supply and control part of the electric motor and its outputs are connected to the electric motor, characterized in that the control unit (13) for the operating mode for Elektrodendrahtvorschub a stabilized Speisequeile (14), ar> whose output is a series circuit of a Steuermultivibrator (IS ) with separately controlled values of the current pulse duration and the pause time, a signal power amplifier (19), a control relay (20), at whose output, a group of k controlling the engagement of the electric drive motor (5) for the electrode wire feed mechanism (4) ontaktlosen control elements. (22) is connected, and a sailing unit (21) for the trailing edge steepness of the current pulse is at the output another group of the electric drive motor (5) for the Elsktrodendrahtvorschubmechanisfiius (4) umsteuerndan contactless control elements (23) is connected, wherein the outputs of the two groups of elements (22; 23) are connected to the electric motor (5). - For this 2-page drawings -