SU1581503A1 - Method of welding with magnetically-controlled arc - Google Patents

Abstract

The invention relates to arc welding, preferably a non-consumable electrode in shielding gases with an external transverse magnetic field applied to the arc, and can be applied in mechanical engineering and other sectors of the metalworking industry in the manufacture of parts when it is necessary to control the heat input along the weld width in the process. welding. The purpose of the invention is to improve the quality of the welded joint in hard-to-reach places. When moving the arc from one extreme position to the other, the standby mode of the arc is set. When the arc reaches its extreme position, it is switched to the welding mode at the time of the arc moving in the welding direction in the extreme deviated position. The arc is kept in the extreme deflected position, adjusting the strength of the magnetic field so that the arc at the maximum strength of the welding current remains in the extreme deflected position to a predetermined value. After the pulse time has elapsed, the current and the intensity of the magnetic field are simultaneously reduced to the value required to keep the pilot arc in a deviated position to a predetermined value. The simultaneous increase in the intensity of the magnetic field in the arc gap with an increase in the welding current in a pulse allows the amplitude of the arc oscillation to be kept constant, which increases the heat input in the given extremely deviated arc positions. Independent adjustment of the duty and welding arc current allows changing the shape of the fusion in a wide range, without changing the width. 2 Il.

Description

The invention relates to arc welding with a predominantly non-fusible electrode with shielding gases with an external transverse magnetic field applied to the arc and can be used in mechanical engineering and other areas of the metalworking industry in the manufacture of parts when it is necessary to control the nature of heat input across the width of the weld during the welding process.

The purpose of the invention is to improve the quality of the welded joint in hard-to-reach places.

Fig. 1 shows a graph of the relationship between the change in the arc current strength, the magnetic field strength in the arc gap, and the path of movement of the active arc spot) in FIG. 2 is a block diagram of an apparatus for implementing a magnetically controlled arc welding method.

The method consists in that the arc is moved across the seam by an external transverse magnetic field and delays it in the extreme deviated position for a predetermined period of time, when the arc moves from one extreme position to the other, the standby mode of the arc is set, and when the arc reaches its extreme position to the welding mode at the time of the arc movement in the welding direction in the extreme deflected position, while keeping the arc in the extreme deflected position, adjusting the intensity of the magnetic field.

The intensity of the magnetic field is adjusted so that the arc, with the maximum strength of the welding current, remains in its extreme deflected position until. of this value, and after the pulse time has elapsed, the current strength and magnetic field strength are reduced to the values necessary to keep the pilot on duty in the deflected position to a predetermined value. As a result, the arc reached the specified deflected position, while simultaneously increasing the arc current and the voltage the magnetic field of the arc remains in this position.

A simultaneous increase in the magnetic field voltage in the arc gap with an increase in the strength of the welding current in a pulse allows the arc oscillation amplitude to be kept constant, which increases the heat input to the given extreme deviated arc positions, and the control current of the standby and welding arcs allows wide limits to change the shape of the fusion, not changing the width of the seam.

Simultaneously with the initiation of the duty arc between the tungsten electrode and the product, the intensity of the external magnetic field in section I-II (Fig. 1) increases to a predetermined value of X, which leads to a deviation of the arc arc from the axis of the weld for a given gap B, (FIG. ,.), When reaching on

By the strength of the external magnetic field, the values of AND arc are transferred to the welding mode and increase the welding power.

current to value I

Cfi

Increase by 0

five

0

five

Q

0

35

45

50

55

9, the external magnetic field strength in region II-III to the value of H2, at which the welding arc is held in a given deflected position. In section III-IV, the magnetic field strength is kept constant, while the welding arc in a deviated position to a predetermined value moves in the welding direction with a welding speed Vcg. After a predetermined period of time of action of the welding arc (point IV, Fig. 1), the strength of the welding current is reduced to the value I, while reducing the strength of the magnetic field in section IV-V to the value B ,. In section V-VI, the magnetic field strength is reduced to zero, while the arcing arc moves to the weld axis, the polarity of the external magnetic field is changed, and the cycle is repeated.

An example. The method is carried out at argon-arc welding of reforming furnace tubes from steel 45X25H20C with a diameter of 120 mm and a wall thickness of I8 mm. The cutting is performed without beveling the edges with a width of 8 mm. The diameter of the tungsten electrode is 4 mm. Welding mode: standby current I, 60 A, arc welding current 1C6 180 A, arc burning time Cr 0.6 s, welding arc burning time in the extreme deflected position b 1 1-2, welding speed VC6 9 m / h, the arc length is 5 mm, the diameter of the filler wire is d 1.2 mm, the number of passes is 5. The welding arc at the indicated modes is deflected across the weld to the junction point of the weld metal with the weld edge, while the external magnetic field strength is controlled the duty arc H1 is 20 3, the welding arc H 4 60 E.

The device for implementing the welding method comprises a control signal generation unit 1, including an integrator 2, a comparator 3 and a one-shot 4, a source of direct current arc supply 5 5, including a welding current control unit 6 and a current sensor 7 matching amplifier 8 , analog multiplier 9, electromagnet 10, creating

51

external alternating transverse magnetic field in the arc burning zone.

The output of the integrator 2 is connected to the first input of the analog multiplier 9 and the first input of the comparator 3, to the second input of which a reference voltage is applied. The output of the comparator 3 is connected to the input of the integrator 2 and the input of the one-shot 4, the output of which is connected to the input of the welding current control unit 6 of the welding arc power source 5 and the blocking input of the integrator 2. The input of the matching amplifier 8 is connected to the current sensor 7 and the output to the second input analog multiplier 9, the output of which is connected to the coil of an electromagnet 10, creating an external alternating transverse magnetic field in the burning zone of the arc.

The device works as follows.

Integrator 2 Generates a linearly varying voltage U fp (section I-II, Figure 1), which is fed to an analog multiplier 9 and the first input of the comparator 3, to the second input of which serves the reference voltage U, determining the amplitude of the control signal U . When Uvnp reaches a given level, which corresponds to the intensity of the external magnetic field at a given deviation of the pilot arc, a comparator 3 is triggered, the signal from which is fed to the integrator, switching the polarity of the output signal, and the one-shot 4. The one-oscillator 4 forms a pulse, the beginning of which determines the moment switching on the welding current impulse from the current control block and integrator blocking (point II, Figure 1). In section II-III (Fig. 1), the integrator produces a constant signal, which corresponds to the movement of the welding arc in a given deflected position. The end of the pulse from the one-shot 4 determines the instant of switching off the welding current and unlocking the integrator (point III, figure 1). After I remove

815036

By blocking, the integrator generates a signal of opposite polarity (section III-IV, Figure 1), which corresponds to the movement of the arc to another predetermined deviated position relative to the axis of the seam, after which the cycle repeats.

The second input of the analog multiplier JQ of bodies 9 is continuously supplied with the feedback signal from the current sensor 7, amplified by a matching amplifier and, in accordance with the law of changing the intensity of the external magnetic field 15 from changing the arc current at a given amplitude of its oscillation K- Ug.

The resulting control signal from the output of the analog multiplier Upv + Uyr, p K U j, depending on U to,

-)

and determining the amplitude of oscillation of the arc, and the parameter of the welding circuit with a constant proportionality coefficient K, is fed to the coil of the electromagnet 10, which creates an external

25 control magnetic field in the arc burning zone, which makes it possible to stabilize the oscillation amplitude of the pilot arc and the movement of the welding arc in a given deflected position.

Claims (1)

Invention Formula The method of welding with a magnetically controlled arc, in which the arc oscillates cross seam transverse magnetic field and delay the arc in the extreme deviated position for a specified period of time, characterized in that, in order to improve the quality of the welded joint in hard-to-reach places, as the arc moves from one extreme position to the other, the standby mode of arc burning sets upon reaching With the arc of the extreme position, the arc is switched to the welding mode for the time of the arc moving in the welding direction in the extreme deflected position, while the arc is kept in the extreme deflected position, adjusting the magnetic field strength. .SC ten Woo