CN108372343B

CN108372343B - Arc welding device, arc welding method, and magnetic control device for arc welding

Info

Publication number: CN108372343B
Application number: CN201711384110.2A
Authority: CN
Inventors: 田中伸明; 高梨不二雄
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 2017-01-30
Filing date: 2017-12-20
Publication date: 2020-05-05
Anticipated expiration: 2037-12-20
Also published as: KR20180089278A; KR102051277B1; CN108372343A; JP6817092B2; JP2018122310A

Abstract

The invention provides an arc welding device, an arc welding method and a magnetic control device for arc welding, which can restrain arc interference and magnetic blow without being influenced by construction conditions such as welding posture, inter-electrode distance and the like, thereby realizing high-quality welding with high efficiency. The arc welding device has two or more electrodes composed of one or both of a non-consumable electrode and a consumable electrode. The arc welding device is provided with: a pair of magnetic coils (65, 67) provided on at least the two axillary sides of the electrode (41) disposed closest to the ground connection portion of the workpiece (19) among the plurality of electrodes; a coil excitation unit (61) that excites the pair of magnetic coils (65, 67) to generate magnetic flux; and a control unit that changes external magnetism around the arc in accordance with the relative positions of the electrode (41) and the pair of magnetic coils (65, 67) and the magnetic fluxes from the electrode (41) and the magnetic coils (65, 67).

Description

Arc welding device, arc welding method, and magnetic control device for arc welding

Technical Field

The invention relates to an arc welding device, an arc welding method and a magnetic control device for arc welding.

Background

As for Arc Welding such as Welding using a consumable electrode (Gas Metal Arc Welding: GMAW) or Welding using a non-consumable electrode (Tungsten Inert Gas: TIG), a technique for improving efficiency by using a plurality of electrodes is known. However, welding by a plurality of electrodes causes arc interference when the inter-electrode distance between the electrodes is short. On the other hand, when the inter-electrode distance is long, magnetic blow is easily generated. Therefore, in welding using a plurality of electrodes, there is a problem that welding quality becomes unstable due to melting failure caused by arc instability, poor appearance of a weld bead, and the like. Further, these arc instabilities are also affected by the welding attitude, and for example, there is a problem that sagging of the weld bead is increased in vertical and horizontal welding.

To solve such a drawback, for example, patent documents 1 and 2 are known. In the arc welding method using a two-electrode non-consumable electrode of patent document 1, two non-consumable electrodes facing each other are used as cathodes, and an arc is alternately generated from the two non-consumable electrodes to form one molten pool (hereinafter, referred to as a single molten pool), and welding is performed while feeding an additive material to the molten pool. Patent document 1 describes that in this arc welding method, a single molten pool is formed by two non-consumable electrodes, and the arcs of the two electrodes do not interfere with each other, so that the molten pool is stable over a wide range. Further, it is described that the width of the weld bead and the width of the weld pool can be adjusted according to the distance between the two electrodes, and therefore, fusion defects that are likely to occur during the laminate welding can be eliminated.

In the multi-electrode welding method of patent document 2, in the horizontal multi-electrode welding, a plurality of electrodes of the torch body are arranged in the width direction of a groove formed in the horizontal direction of the base material, out of the wall in which the groove is formed. That is, the method of patent document 2 is a multi-electrode welding method in which welding is performed by generating an arc between a base material and a plurality of electrodes, and when one of walls forming a groove is located lower than the other wall, the postures of the plurality of electrodes are controlled so that the arc is deflected toward the lower wall. Thus, patent document 2 describes that the melting of the lower side of the groove is promoted, the lower side is prevented from becoming insufficiently melted, the generation of a flash portion is prevented, and the sagging of the molten metal on the upper side is also suppressed.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 5-131273

Patent document 2; japanese laid-open patent publication No. 2002-1537

Disclosure of Invention

Problems to be solved by the invention

However, patent document 1 assumes single-puddle welding. The method of generating the arcs mutually by using the welding current as the pulse current can only obtain an effect of preventing the interference of the arcs caused when the distance between the electrodes is short. That is, for the purpose of dispersing the input heat, as shown in fig. 12, when the distance between the

electrodes

501 and 503 is increased to form the double melt pools, the influence of the magnetic blow cannot be prevented. When the same direction current (for example, 150A) is used, magnetic lines of force B1 and B2 are generated in the same direction at the electrode 501 and the electrode 503. In particular, when the ground connection portion of the ground line 507 of the workpiece 505 is limited to be provided at only one position (position P in the drawing), the total current flowing between the electrode 503 and the ground line 507 is larger than the total current flowing between the electrode 501 and the electrode 503 (I1 < I2). Therefore, a magnetic field larger than that of the other portions is generated in the electrode 503 at the position P close to the ground connection portion connected to the ground line 507, and magnetic blow (Mb1 < Mb2) becomes remarkable. Patent document 1 does not describe any welding position such as a horizontal direction and a vertical direction.

In patent document 2, a weld beading and a bite which are likely to occur in a horizontal welding posture are suppressed in a plurality of electrodes, but a single weld pool having a short distance between electrodes is assumed, and no consideration is given to a double weld pool. Further, the problems of arc interference and magnetic blow are not considered in particular. Even if patent document 1 and patent document 2 are combined, magnetic blow, which is a problem in welding with two or more weld pools, cannot be solved.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an arc welding apparatus, an arc welding method, and a magnetic control apparatus for arc welding that can efficiently realize high-quality welding by suppressing arc interference and magnetic blow without being affected by construction conditions such as a welding posture and an inter-electrode distance.

Means for solving the problems

One aspect of the present invention can provide an arc welding apparatus in which two or more electrodes including one or both of a non-consumable electrode and a consumable electrode are arranged along a welding direction, and a welding current is applied between the electrodes and a workpiece to generate an arc,

the arc welding device is provided with: a pair of magnetic coils provided on both the axilla sides of at least an electrode disposed closest to the ground connection portion of the workpiece, among the plurality of electrodes, with the electrode interposed therebetween; a coil exciting section that excites the pair of magnetic coils to generate magnetic flux; and a control unit that changes an external magnetic field around the arc according to a relative position between the electrode and the pair of magnetic coils and a magnetic flux from the electrode and the pair of magnetic coils.

In addition, an aspect of the present invention can provide an arc welding method in which two or more plural electrodes each including one or both of a non-consumable electrode and a consumable electrode are arranged along a welding direction, and a welding current is applied between the plural electrodes and a workpiece to generate an arc, wherein a pair of magnetic coils on both axilla sides sandwiching the electrode, which is provided at least on the electrode arranged closest to a ground connection portion of the workpiece among the plural electrodes, is excited to generate a magnetic flux, and an external magnetic field around the arc is changed according to a relative position of the electrode and the pair of magnetic coils and the magnetic flux from the magnetic coils.

In addition, an aspect of the present invention can provide a magnetic control device for arc welding that controls directivity of an arc generated by an electrode including a non-consumable electrode or a consumable electrode, the magnetic control device for arc welding including: a magnetic coil having a pair of winding portions formed by winding a lead wire at each of front end portions of a U-shaped iron core; a coil moving mechanism that supports the magnetic coil movably in a welding direction while sandwiching the electrode between a pair of the winding portions; a coil exciting section that excites the magnetic coil to generate magnetic flux; and a control unit that changes an external magnetic field around the arc according to a relative position between the electrode and the pair of winding portions and a magnetic flux from the electrode and the pair of magnetic coils.

Effects of the invention

According to the arc welding apparatus and the arc welding method of the present invention, it is possible to suppress arc interference and magnetic blow and realize high-quality welding with high efficiency without being affected by construction conditions such as a welding posture and an inter-electrode distance.

Further, according to the magnetic control device for arc welding of the present invention, it is possible to generate an external magnetic field capable of suppressing arc interference and magnetic blow without being affected by construction conditions such as a welding posture and an inter-electrode distance.

Drawings

Fig. 1 is an external view of an arc welding apparatus according to a first configuration example.

Fig. 2 is a perspective view of a main part of the arc welding apparatus shown in fig. 1.

Fig. 3 is a partially enlarged view of the arc welding apparatus shown in fig. 2.

Fig. 4 is a schematic plan view of the first coil unit, the second coil unit, and the first welding torch and the second welding torch.

Fig. 5 is a schematic explanatory diagram showing a positional relationship between an electrode of the welding torch and the coil unit.

FIG. 6 is a control block diagram of an arc welding system.

Fig. 7 is an operation explanatory diagram showing positions of the electrode and the magnetic coil and a direction of current when electromagnetic force toward the upstream side in the welding direction acts on the arc.

Fig. 8 is an operation explanatory diagram showing positions of the electrode and the magnetic coil and a direction of current when electromagnetic force toward the downstream side in the welding direction acts on the arc.

Fig. 9 is an explanatory diagram showing the positions of the electrodes and the magnetic coils and the direction of the current when an electromagnetic force directed to one side orthogonal to the welding direction acts on the arc.

Fig. 10 is an explanatory diagram showing the positions of the electrodes and the magnetic coils and the direction of the current when an electromagnetic force directed to the other side orthogonal to the welding direction acts on the arc.

Fig. 11 is a main part configuration diagram of an arc welding apparatus of a second configuration example.

Fig. 12 is an explanatory diagram illustrating the cause of magnetic blow in the conventional double-puddle arc welding method.

Description of reference numerals:

19 workpiece

25 welding wire feeding head

27 gas suction part

39 first welding torch

41 electrode

43 second welding torch

47. 48 biaxial slide block

57 first coil unit

59 second coil unit

61 coil exciting part

65 magnetic coil

67 magnetic coil

68 winding part

69 iron core

71. 72 coil moving mechanism

73 control part

100. 300 arc welding device

200 arc welding system

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

The arc welding apparatus of the present invention is not particularly limited in its welding method as long as it is configured to perform arc welding. For example, the present invention can also be applied to gas-shielded non-consumable electrode arc welding such as TIG welding, and gas-shielded consumable electrode arc welding such as MIG welding and carbon dioxide arc welding.

Here, as the arc welding apparatus, an apparatus that performs TIG welding in which welding is performed while moving upward by vertical welding is exemplified, but the arc welding apparatus is not limited to this, and may be applied to any welding posture, and may also be applied to welding in the lateral direction or the downward direction.

[ first structural example ]

Fig. 1 is an external view of an arc welding apparatus according to a first configuration example. In this specification, the direction of the Z axis is a welding direction, the direction of the Y axis is a normal line direction of a welding surface, the direction of the X axis is a direction orthogonal to the welding direction and the normal line of the welding surface, and each direction is represented by an arrow in fig. 1.

The arc welding apparatus 100 is a main apparatus of an arc welding system 200 (see fig. 6) described later. The workpiece 13 has a bevel portion 15, and a rail 11 and a carriage 17 movable along the rail 11 are disposed on the front side of the workpiece 13. An arc welding device 100 is mounted on the carriage 17, and welding of the bevel portion 15 is performed. The arc welding apparatus 100 of the present configuration is configured to be capable of vertical welding from a lower vertical direction to an upper vertical direction along the rail 11. In addition, various power sources, a gas supply unit, a cooling water supply unit, and the like, which will be described later, are connected to the arc welding apparatus 100.

Fig. 2 is a perspective view of a main part of the arc welding apparatus 100 shown in fig. 1. Fig. 2 shows the arc welding apparatus 100 shown in fig. 1 in a state in which the rail 11 is horizontally disposed to be located below.

The carriage 17 of the arc welding apparatus 100 includes a base 21 attached in parallel to the rail 11 and a motor 29 for moving the base. The base 21 is provided with a first coil unit 57, a first torch unit 35, a second torch unit 37, and a second coil unit 59 from the upstream side in the welding direction (the left side in fig. 2). Each of the first torch unit 35 and the second torch unit 37 includes a slide portion, not shown, that is movable on the base 21. The base 21 is provided with a wire reel 23 for supplying a filler wire, a wire feeding head 25, a gas suction portion 27, a motor 29, an operation portion 31, and the like, and the base plate 21 is configured to be movable along the rail 11 by driving of the motor 29.

The first torch unit 35 has a biaxial slider 47 and a first torch 39 attached to the biaxial slider 47. First welding torch 39 incorporates an electrode for arc welding, not shown. The second torch unit 37 also has a biaxial slider 48 and a second torch 43 attached to the biaxial slider 48. The second welding torch 43 also incorporates an electrode for arc welding, not shown.

The first welding torch 39 and the second welding torch 43 can be independently moved by the

biaxial sliders

47 and 48. The

biaxial sliders

47 and 48 each have a lateral sliding portion 51 that can slide, i.e., oscillate, the first welding torch 39 and the second welding torch 43 along the X-axis direction, which is the width direction of the groove of the workpiece 19, and a longitudinal sliding portion 53 that can slide the welding torches along the Y-axis direction, which is the thickness direction of the workpiece 19.

The lateral sliding portion 51 and the vertical sliding portion 53 have a power transmission mechanism or the like for transmitting power of a motor, not shown, and automatically slide the electrodes of the respective welding torches in the X-axis direction and the Y-axis direction, respectively. Further, each welding torch may be oscillated during welding.

The first coil unit 57 includes a pair of

magnetic coils

65 and 67 so as to sandwich the first welding torch 39 in the X-axis direction. The magnetic coils 65 and 67 include a core 69 as a magnetic core and a winding portion 68 around which a wire is wound, and generate an external magnetic field for deflecting an arc. The shape of the core 69 is not particularly limited, and may be, for example, a horseshoe shape (U-shape). In this case, the winding portions 68 may be provided at the pair of distal end portions of the U shape.

Second coil unit 59 has the same configuration as first coil unit 57, and includes a pair of

magnetic coils

65 and 67 so as to sandwich second welding torch 43 in the X-axis direction. The magnetic coils 65 and 67 include horseshoe-shaped (U-shaped) cores 69 serving as magnetic cores, and winding portions 68 around which wires are wound.

First coil unit 57 and second coil unit 59 are disposed to be inclined outward between the welding torches 39 and 43 disposed in parallel to the Y axis direction. Therefore, the

magnetic coils

65 and 67 are disposed in a state where the tip of the core 69 is obliquely inserted into both sides of the welding torches 39 and 43.

The first coil unit 57 is supported by the coil moving mechanism 71. One end of the coil moving mechanism 71 is fixed to the base 21 and supports the first coil unit 57. Coil moving mechanism 71 includes sliders oriented in the Z-axis direction, the X-axis direction, and the Y-axis direction, and supports first coil unit 57 such that the relative position to welding torch 39 can be changed.

The second coil unit 59 is supported by a coil moving mechanism 72 having the same configuration as the coil moving mechanism 71 so that the relative position to the welding torch 43 can be changed.

The

coil moving mechanisms

71 and 72 may be configured to move the first coil unit 57 and the second coil unit 59 by motor driving, or may be configured to manually move the first coil unit 57 and the second coil unit 59. The

coil moving mechanisms

71 and 72 may be only mechanisms for fixing the first coil unit 57 and the second coil unit 59 at desired positions.

Further, a gas suction portion 27 is disposed between the first welding torch 39 and the second welding torch 43. The gas suction unit 27 is disposed at an intermediate position between the first welding torch 39 and the second welding torch 43, and sucks the ambient gas including spatters and fumes generated from the second welding torch 43 and the surplus shielding gas. Preferably, the suction amount is 0.1 to 2.0 (m)³Min) in the range ofAnd (4) attracting.

Instead of the gas suction portion 27, a shielding member such as a plate member for shielding the surrounding space may be provided between the welding torches for each welding torch. Further, the gas suction portion 27 and the shielding member may be provided together.

The

biaxial sliders

47 and 48 change the welding positions and torch intervals of the first welding torch 39 and the second welding torch 43 in accordance with the shape of the workpiece 19. The

coil moving mechanisms

71 and 72 change the relative positions of the welding torches 39 and 43 and the

magnetic coils

65 and 67 in accordance with the movement of the welding torches 39 and 43.

Fig. 4 is a schematic top view of first coil unit 57, second coil unit 59, and first welding torch 39, second welding torch 43.

The first coil unit 57 and the second coil unit 59 are arranged such that open ends of horseshoe-shaped (U-shaped) cores 69 face each other and the axial direction of the winding portion 68 is parallel to the Z-axis direction. The interelectrode distance Wt between the electrode 41 of the first welding torch 39 and the electrode 41 of the second welding torch 43 is preferably 50mm to 400 mm. By setting the inter-electrode distance Wt to 50mm or more, the heat input to the workpiece can be suppressed, and by setting the inter-electrode distance Wt to 400mm or less, the appearance of the weld can be further improved.

Fig. 5 is a schematic explanatory diagram showing a positional relationship between an electrode of the welding torch and the coil unit. In the illustrated example, only first coil unit 57 and first welding torch 39 are shown, but the same applies to second coil unit 59 and second welding torch 43. Fig. 5 is a plan view of the

magnetic coils

65 and 67 viewed from a direction perpendicular to the coil axis Lx, and the electrode 41 of the first welding torch 39 in the drawing shows the electrode tip position.

The magnetic coils 65 and 67 are arranged with their coil axes Lx parallel to each other around the electrode 41. The electrode 41 is disposed so as to be movable relative to the

magnetic coils

65 and 67 in the welding direction, i.e., the Z-axis direction. The movable distance Ls of the relative movement is preferably within 1.5 times the axial total length Lc of the winding portion 68 around the midpoint Oc of the axial total length Lc of the winding portion 68 of the

magnetic coils

65, 67.

That is, the electrode 41 and the

magnetic coils

65 and 67 can pass through the lateral sliding portions 51 of the

biaxial sliders

47 and 48 and the

coil moving mechanisms

71 and 73, and both relative positions can be changed between the distances Ls.

The magnetic coils 65 and 67 may be formed by 1600 turns of the wire in the winding portion 68, and the axial distance Wc between the coil axes Lx of the

magnetic coils

65 and 67 is in the range of 80mm to 200 mm. By making the number of turns of the wire 800 or more, shortage of the magnetic field does not occur, and by making the number of turns of the wire 1600 or less, coarsening of the outer diameter of the magnetic coil does not occur. Further, interference between the magnetic coil and the electrode can be suppressed by setting the distance between the pair of winding portions to 80mm or more, and a shortage of the magnetic field is less likely to occur by setting the distance between the pair of winding portions to 200mm or less. The inter-axis distance Wc can be increased or decreased as appropriate according to the shape of the component. In addition, the number of turns of the wire may be increased or decreased as appropriate according to a desired magnetic flux density applied to the arc spot.

The relative positions of the electrode 41 and the

magnetic coils

65 and 67 are adjustment parameters for deflecting the arc generated from the electrode 41, as will be described later.

Fig. 6 is a control block diagram of the arc welding system 200.

The arc welding system 200 includes a control unit 73 provided separately from the arc welding apparatus 100 mounted on the carriage 17.

The control unit 73 controls the operation of each part constituting the arc welding apparatus 100. For example, control unit 73 controls operations such as movement of carriage 17 by motor 29, sliding of first welding torch 39 and second welding torch 43 by

biaxial sliders

47 and 48, sliding of first coil unit 57 and second coil unit 59 by

coil moving mechanisms

71 and 72, and feeding of filler wire by wire feeding head 25.

The coil exciting portion 61 for supplying electric power to the magnetic coils 65 and 67 (see fig. 3) of the first coil unit 57 and the second coil unit 59 is connected to the control portion 73. The control unit 73 outputs the coil excitation power input from the coil excitation unit 61 to the first coil unit 57 and the second coil unit 59, respectively. The control unit 73 has a function of controlling the amount of power supplied to the

magnetic coils

65 and 67 and reversing the direction of current. In this way, the controller 73 has a function of changing the external magnetic field around the arc of the first welding torch 39 and the second welding torch 43 by reversing the field polarity or changing the coil position by the

coil moving mechanisms

71 and 72. The reversal of the excitation polarity and the movement of the coil position may be performed by the control unit 73, but may be performed by a controller or the like provided separately from the control unit 73.

The control unit 73 is connected to the operation unit 31 via a relay unit 33 mounted on the carriage 17. The operation unit 31 includes operation buttons, a display unit, and the like, not shown, for setting welding conditions, control conditions of the coil unit, and the like. The operation buttons receive an operation from the user to change the setting of the welding conditions specified in the welding operation, an operation to start the welding operation, and the like. Further, operation unit 31 has a connector connected to an external memory, and welding conditions sent from control unit 73 during the welding operation are stored in the external memory connected to the connector. The external memory is a storage medium provided to be detachable from the operation unit 31, and for example, a flash memory is used from the viewpoint of general use, large capacity, and small size.

The display unit of the operation unit 31 is constituted by a liquid crystal monitor or the like, and displays the contents of the welding conditions, error information, and the like. Here, the error information is information related to an error occurring before the welding operation or during the welding operation. The error information includes information related to an error such as an arc interruption, an arc stop, an electrode short circuit, a servo abnormality, and a power supply abnormality.

Further, the arc welding system 200 includes: TIG welding

power supplies

75A and 75B that generate an arc by applying a welding voltage to each electrode of first welding torch 39 and second welding torch 43;

MC power supplies

77A, 77B that supply electric power to the filler wires of the respective electrodes via the wire feed head 25; a cooling water circulation drive unit 79 for circulating cooling water through each torch; and a shielding gas supply driving unit 91 for supplying shielding gas to each torch. These components are also connected to the control unit 73 and are driven and controlled.

TIG

welding power supplies

75A and 75B apply welding voltages between the respective electrodes of first welding torch 39 and second welding torch 43 and the workpiece. The

MC power sources

77A and 77B supply a known arc adjustment voltage via a filler wire. The ground lines E of the TIG

welding power sources

75A, 75B,

MC power sources

77A, 77B are connected to the workpiece via the ground connection portion of the workpiece.

The shielding gas supply driving unit 91 is connected to an Ar gas cylinder 95 provided with a pressure controller 93 via a gas hose 97, and supplies argon gas fed from the Ar gas cylinder 95 to the first welding torch 39 and the second welding torch 43 via a gas hose 99.

The cooling water circulation drive unit 79 circulates the cooling water through the first welding torch 39 and the second welding torch 43. The cooling water circulation drive unit 79 cools the cooling water returned from these torches to a predetermined temperature by heat exchange, and then supplies the cooling water to each torch again to cool the torch.

In the arc welding system 200, all the controls may be performed by one control unit 73, but separate control units may be provided for each application. For example, a control unit that controls electric power supplied from the TIG

welding power sources

75A and 75B to between the electrode and the workpiece, electric power supplied from the

MC power sources

77A and 77B to the filler wire, and a control unit that controls electric power supplied from the coil exciting unit 61 to the coil unit may be provided separately from the control unit 73.

Further, during the welding operation, the control unit 73 stores the welding conditions in an internal memory of the control unit 73, and transmits the welding conditions stored in the internal memory to an external memory connected to the connector of the operation unit 31.

Next, the operation of the arc welding apparatus 100 configured as described above will be described.

Hereinafter, the generation of an external magnetic field by the magnetic coil and the suppression of arc interference and magnetic blow will be described with reference to fig. 7 to 10.

Fig. 7 is an explanatory diagram showing the positions of the electrodes and the magnetic coil and the direction of the current when an electromagnetic force for directing the arc to the upstream side in the welding direction is applied. Since first coil unit 57 and second coil unit 59, and first welding torch and second welding torch 43 have the same configuration, both of them obtain the same operation.

The magnetic flux density and the magnetic lines of force vary depending on the relative positions of the electrode 41 and the

magnetic coils

65, 67, the current applied to the

magnetic coils

65, 67, the direction of the current, and the magnetic flux density. For example, under the conditions of direct current and negative electrode polarity (DCEN), the electrode 41 is disposed on the downstream side of the

magnetic coils

65 and 67 in the welding direction WD, and current flows through the magnetic coil 65 so that the upstream side in the welding direction WD becomes an N-pole (in the direction of arrow D1 in the figure), and current flows through the magnetic coil 67 so that the downstream side in the welding direction WD becomes an N-pole (in the direction of arrow D2 in the figure). Then, the directions of the magnetic lines of force LMF1 generated by the magnetic coil 65, the magnetic lines of force LMF2 generated by the magnetic coil 67, and the magnetic lines of force LMF3 generated by the electrode 41 coincide in the same direction on the downstream side in the welding direction WD of the electrode 41, and the magnetic flux density becomes high. On the other hand, the magnetic lines of force from the

magnetic coils

65 and 67 and the electrode 41 are not aligned in other portions around the electrode 41, and the magnetic flux density is relatively low. As a result, the resultant magnetic force lines LMF of the portion having a high magnetic flux density mainly act on the arc generated from the electrode 41 during welding, and the electromagnetic force EMF acts on the upstream side in the welding direction WD.

The direction of the electromagnetic force EMF acting on the arc varies depending on the orientation of the current of the electrode 41, the

magnetic coils

65, 67, and the relative positions of the electrode 41 and the

magnetic coils

65, 67. Therefore, in the arc welding apparatus of the present configuration, the control section 73 (see fig. 6) controls the directions of the currents of the electrode 41 and the

magnetic coils

65 and 67 and the relative positions of the electrode 41 and the

magnetic coils

65 and 67, thereby deflecting the arc toward the upstream side in the welding direction with respect to the welding direction WD.

Fig. 8 is an operation explanatory diagram showing positions of the electrode and the magnetic coil and a direction of current when electromagnetic force toward the welding direction downstream side acts on the arc.

Under the same conditions as the applied current in the case shown in fig. 7, when the electrode 41 is disposed on the upstream side in the welding direction WD of the

magnetic coils

65 and 67 as shown in fig. 8, the directions of the magnetic lines of force LMF1 from the magnetic coil 65, the magnetic lines of force LMF2 from the magnetic coil 67, and the magnetic lines of force LMF3 from the electrode 41 coincide in the same direction on the upstream side in the welding direction of the electrode 41, and the magnetic flux density increases. On the other hand, the magnetic lines of force from the

magnetic coils

65 and 67 and the electrode 41 are not oriented uniformly in other portions around the electrode 41, and the magnetic flux density is relatively reduced. As a result, the resultant magnetic force lines LMF of the portions having high magnetic flux density mainly act on the arc generated from the electrode 41 during welding, and the electromagnetic force EMF acts on the downstream side in the welding direction WD.

As shown in fig. 7 and 8, by changing the relative positions of the electrode 41 and the

magnetic coils

65 and 67 along the welding direction WD, the direction of the electromagnetic force acting on the arc generated from the electrode 41 can be adjusted to either the upstream side or the downstream side in the welding direction WD. Further, the intensity of the electromagnetic force can be adjusted by increasing or decreasing the applied current to the

magnetic coils

65 and 67.

Fig. 9 is an explanatory diagram showing the positions of the electrodes and the magnetic coils and the direction of the current when an electromagnetic force directed to one side (right side in the figure) orthogonal to the welding direction acts on the arc.

As in the case of fig. 7 and 8, under the conditions of the direct current and the negative electrode polarity (DCEN), the electrode 41 is disposed at the center of the

magnetic coils

65 and 67 in the welding direction WD, and the current flows through the

magnetic coils

65 and 67 so that the upstream side in the welding direction WD becomes the N-pole (the direction of arrows D1 and D2 in the drawing). Then, the direction of the magnetic lines of force LMF2 generated by the magnetic coil 67 and the direction of the magnetic lines of force LMF3 generated by the electrode 41 coincide in the same direction on one side (the left side in the drawing) orthogonal to the welding direction WD of the electrode 41, and the magnetic flux density increases. On the other hand, the magnetic lines of force from the

magnetic coils

65 and 67 and the electrode 41 are not aligned in other portions around the electrode 41, and the magnetic flux density is relatively reduced. As a result, the resultant magnetic force lines LMF mainly acting on the arc generated from the electrode 41 during welding at a portion having a high magnetic flux density act on the electromagnetic force EMF on the other side (right side in the drawing) perpendicular to the welding direction WD.

Fig. 10 is an explanatory diagram showing the positions of the electrodes and the magnetic coils and the direction of the current when an electromagnetic force directed to the other side (left side in the drawing) orthogonal to the welding direction acts on the arc.

In the case of fig. 10, the same conditions as in the case of fig. 9 are applied except that the polarities of the

magnetic coils

65 and 67 are reversed as compared with the case of fig. 9. In this case, the direction of the magnetic lines of force LMF1 generated by the magnetic coil 65 and the direction of the magnetic lines of force LMF3 generated by the electrode 41 coincide in the same direction on the other side (right side in the drawing) orthogonal to the welding direction WD of the electrode 41, and the magnetic flux density increases. On the other hand, the magnetic lines of force from the

magnetic coils

65 and 67 and the electrode 41 are not aligned in other portions around the electrode 41, and the magnetic flux density is relatively reduced. As a result, the resultant magnetic force lines LMF of the portion having a high magnetic flux density mainly act on the arc generated from the electrode 41 during welding, and the electromagnetic force EMF acts on one side (left side in the drawing) perpendicular to the welding direction WD.

As shown in fig. 9 and 10, by arranging the electrode 41 at the center of the welding direction WD of the

magnetic coils

65 and 67, changing the polarity of the

magnetic coils

65 and 67 to the same polarity in the welding direction WD, and changing the direction of the current, the direction of the electromagnetic force acting on the arc generated from the electrode 41 can be adjusted to either one of the one side and the other side orthogonal to the welding direction WD. Further, the intensity of the electromagnetic force can be adjusted by increasing or decreasing the applied current to the

magnetic coils

65 and 67.

In this way, the arc welding apparatus 100 can control the arc deflection direction in a total of 4 directions of the upstream direction, the downstream direction, and two directions orthogonal to the welding direction with respect to the welding direction WD, and can eliminate the influence of magnetic blow by generating electromagnetic force in the opposite direction to the direction of magnetic blow when magnetic blow occurs, for example.

Here, the force applied to the arc varies depending on the magnetic flux density at the electrode position, and when the force is less than 10mT, the force applied to the arc is insufficient, and when the force is more than 90mT, the force applied to the arc is excessive. Therefore, the range in which the welding quality can be most stabilized is preferably 10 to 90 mT. In addition, in the case of preventing magnetic blow, the maximum intensity of magnetic blow depends on the total of currents flowing through the plurality of electrodes. Therefore, it is more preferable that the ratio of the total current to the magnetic flux density (total current/magnetic flux density) in the electrode closest to the ground connection portion (the electrode of the second welding torch 43 in the present configuration example) is in the range of 1.5 to 60.0. By setting the ratio of the total current to the magnetic flux density to 60.0 or less, shortage of the magnetic field does not occur, and by setting the ratio of the total current to the magnetic flux density to 1.5 or more, coarsening of the outer diameter of the magnetic coil can be suppressed.

Next, an arc welding method using the arc welding apparatus 100 configured as described above will be described.

The arc welding apparatus 100 can be applied to, for example, welding a side plate of an LNG tank. That is, first welding torch 39 and second welding torch 43 are arranged in the extending direction of groove 49 (see fig. 3) of the workpiece extending in the vertical direction, and welding is performed by generating an arc between workpiece 19 and the electrode of first welding torch 39 and the electrode of second welding torch 43. A rail 11 is attached to the side plate along the groove 49, and the carriage 17 of the arc welding apparatus 100 rides on the rail 11.

In the present configuration example, the arc welding apparatus 100 disposes a pair of non-consumable electrodes (electrodes 41) one on each of the upstream side and the downstream side with respect to the welding direction by TIG welding. These electrodes are arranged at predetermined welding positions in the XYZ-axis direction by the positioning operation of the

biaxial sliders

47 and 48 by the control unit 73 shown in fig. 6. The arc welding apparatus 100 generates an external magnetic field by the

magnetic coils

65 and 67 disposed on both sides of at least one electrode closest to the ground connection portion of the workpiece 19 among the plurality of electrodes.

The arc welding apparatus 100 deflects the arc generated in each of the first welding torch 39 and the second welding torch 43 by the external magnetic field controlled by the control unit 73, and suppresses magnetic blow. The magnetic blow suppression operation is controlled based on each data such as a magnetic blow suppression data table stored in advance. The magnetic blow suppression data table includes information such as the magnetic blow amount (displacement amount) generated in the first welding torch 39 and the second welding torch 43 in accordance with the welding current, and the drive current of each coil unit for correcting the magnetic blow displacement amount. The magnetic blow-out suppression data table is stored in, for example, an internal memory of the control unit 73. The arc welding apparatus 100 stores the drive currents of the coil units together with other welding conditions in the external memory of the operation unit 31 from the control unit 73, and performs welding. Thus, in the present arc welding method, the controller 73 controls the direction of the arc generation position in the upstream and downstream directions with respect to the welding direction and in the total of four directions of two directions orthogonal to the welding direction in accordance with the welding currents of the first welding torch 39 and the second welding torch 43, and welding can be performed with magnetic blow suppressed.

According to the arc welding apparatus 100 of the present configuration described above, the pair of

magnetic coils

65 and 67 are disposed on both sides of the electrode closest to the ground connection portion of the workpiece 19. These

magnetic coils

65, 67 sandwiching the electrode are arranged in a posture in which the axes of the

magnetic coils

65, 67 are along the welding direction of the workpiece 19. The attitude along the welding direction of the workpiece 19 means an attitude parallel to or inclined with respect to the welding surface of the workpiece 19 except perpendicular to the axis of the

magnetic coils

65, 67 of the workpiece 19.

Each electrode 41 of first welding torch 39 and second welding torch 43 is either positive or negative, and a magnetic field is generated around the electrode. On the other hand, a current flows also to the

magnetic coils

65 and 67 sandwiching the electrode 41, thereby generating a magnetic field. The arc is deflected by the magnetic field around these electrodes and the magnetic field of the

magnetic coils

65, 67. The force (electromagnetic force) for deflecting the arc is intensified in a synthetic magnetic field having uniform magnetic lines. The direction of the electromagnetic force changes depending on the direction of the current flowing through the electrode 41 and the

magnetic coils

65 and 67, and the relative positions of the electrode 41 and the

magnetic coils

65 and 67. Therefore, in the arc welding apparatus, the control unit 73 controls the direction and relative position of the current of the electrode and the coil unit, and the arc can be controlled in the total of 4 directions including the welding direction. This can suppress arc interference and magnetic blow.

In the arc welding apparatus 100, the electrode 41 is positioned between the pair of

magnetic coils

65 and 67, and is not separated from the tip of the magnetic coil by a distance exceeding 1.5 times the total length of the coil portion. This ensures the electromagnetic force necessary for deflecting the arc with low power.

Further, the arc welding apparatus 100 has a configuration in which, for example, two electrodes and only one ground wire are provided, and when a current of 150A flows through each electrode, the total current is 300A. Since the magnetic blow becomes larger as the total current becomes larger, a larger magnetic flux density is required to suppress the magnetic blow. Therefore, the range of the ratio of the total current to the magnetic flux density is set to 1.5 to 60.0 as described above.

Further, the arc welding apparatus 100 suppresses the instability of the arc of the electrode (leading electrode) of the welding torch on the upstream side in the welding direction by the gas suction portion 27 (or the shielding member). That is, in the welding in the vertical upward direction, the shielding gas at the electrode (trailing electrode) of the welding torch on the downstream side in the welding direction rises along the groove 49, and the peripheral air is entrained, whereby the arc instability of the leading electrode caused by the shielding gas disturbing the leading electrode can be suppressed. The gas suction portion 27 (or the shield) has a remarkable effect of stabilizing the arc particularly in the vertical welding.

Further, the arc welding apparatus 100 can arbitrarily change the relative positions of the first coil unit 57 and the second coil unit 59 with respect to the electrode of the welding torch by driving the

coil moving mechanisms

71 and 72. By changing the relative position, the direction of the electromagnetic force acting on the arc can be reversed with respect to the welding direction. In addition, the pair of

magnetic coils

65 and 67 can be moved in the separating direction (X-axis direction), and thus the electrodes can be easily positioned at the center in the separating direction.

The arc welding apparatus 100 sets the distance between the electrodes of the first welding torch 39 and the second welding torch 43 to be in the range of 50 to 400 mm. Thus, the distance between the electrodes is set to 50mm or more, whereby the input heat can be suppressed, and the appearance of the weld can be improved by setting the distance between the electrodes to 400mm or less.

Further, the arc welding apparatus 100 can cause the magnetic field generated by the filler wire to act on the arc by changing the current and polarity applied to the filler wire by the

MC power sources

77A and 77B. Therefore, the arc direction control can be assisted by the combination of the formation of the external magnetic field by the first coil unit 57 and the second coil unit 59.

[ second structural example ]

Next, an arc welding apparatus according to a second configuration example will be described.

The arc welding apparatus 300 of the present configuration example includes a welding torch 109 having an electrode 107, a biaxial slider 111, a magnetic coil 65, a magnetic coil 67, and a camera 115. The magnetic coils 65 and 67 are connected to the same coil exciting section 61, and are driven in accordance with a command from the control section 73.

The control unit 73 is connected to the biaxial slider 111 and the camera 115, and is not shown, but is connected to the coil moving mechanisms 71 and 72 (see fig. 3) and the like as described above, and controls the respective units together.

The camera 115 is mounted, for example, in the vicinity of the welding torch so as to be able to photograph the arc. The camera 115 outputs captured image data as output information. The control unit 73 stores output information output from the camera 115 in an image memory provided in an internal memory or the like. The stored image data of the output information is processed in accordance with a program stored in an internal memory, and the posture of the arc, for example, the arc center position is determined. The control unit 73 calculates the amount of deflection of the magnetic blow from the determined arc posture, and drives the coil exciting unit 61 in accordance with the amount of deflection of the magnetic blow.

Accordingly, the arc welding apparatus 300 can return the deflection of the arc caused by the magnetic blow to the normal state by controlling the current applied to the

magnetic coils

65 and 67, the direction of the current, and the coil moving mechanism in accordance with the magnetic blow generated in the arc. As a result, welding can be performed while sequentially suppressing magnetic blow.

Therefore, according to the

arc welding apparatuses

100 and 300 of the above-described configuration examples, arc interference and magnetic blow can be suppressed without being affected by construction conditions such as a welding posture and an inter-electrode distance, and high-quality welding can be efficiently achieved.

[ examples ] A method for producing a compound

Next, an example of arc welding using the above-described configurations 1 and 2 will be described. The welding conditions described here are examples, and the present invention is not limited to the following welding conditions.

The arc welding conditions are more preferably in the following ranges.

Welding current: 80 to 300A

Arc voltage: 5-15V

Welding speed: 5 to 30cm/min

Distance between electrodes: 50-400 mm

When arc welding was performed under the above welding conditions, it was confirmed that both of the configuration examples 1 and 2 can perform high-quality welding while suppressing the occurrence of arc interference and magnetic blow.

As described above, the present invention is not limited to the above-described embodiments, and modifications and applications of the respective configurations of the embodiments by combining them with each other and by those skilled in the art based on the description of the specification and known techniques are also within the scope of the present invention and are included in the scope of protection.

For example, the coil units are disposed in the pair of welding torches, respectively, but the coil units may be disposed only on the welding torch side disposed closest to the ground connection portion of the workpiece.

In addition, both of the pair of welding torches described above are non-consumable electrodes, but may be consumable electrodes, and either one of them may be a non-consumable electrode and the other may be a consumable electrode.

The arc welding apparatus may be configured such that a torch side generating an arc is separated from a coil unit side generating a magnetic field. In this case, the arc welding magnetic control device including the coil unit, the coil moving mechanism, the coil exciting section, and the control section is added to an arbitrary arc welding device, and thereby a universal device configuration is formed.

As described above, the following matters are disclosed in the present specification.

(1) An arc welding apparatus in which two or more electrodes each including one or both of a non-consumable electrode and a consumable electrode are arranged along a welding direction, and a welding current is applied between the electrodes and a workpiece to generate an arc,

the arc welding device is provided with:

a pair of magnetic coils provided at least on both the axillary sides of an electrode, which is disposed closest to the ground connection portion of the workpiece, among the plurality of electrodes;

a coil exciting section that excites the pair of magnetic coils to generate magnetic flux; and

and a control unit that changes an external magnetic field around the arc according to a relative position between the electrode and the pair of magnetic coils and a magnetic flux from the electrode and the pair of magnetic coils.

According to this arc welding apparatus, the magnetic coils are disposed on both sides of the electrode of the ground wire closest to the workpiece. The magnetic coil sandwiching the electrode is disposed in a posture in which an axis of the core is along a welding direction of the workpiece. The electrode becomes positive or negative, and a magnetic field is generated at the electrode itself. On the other hand, a current also flows through the magnetic coil sandwiching the electrode, and a magnetic field is generated. The arc is deflected by the magnetic field of the electrodes themselves, as well as the magnetic field of the individual magnet coils. The electromagnetic force deflecting the arc becomes stronger when the magnetic lines of force from the respective portions are aligned. The direction of the electromagnetic force changes depending on the electrode, the direction of the current of the magnetic coil, and the relative positions of the electrode and the magnetic coil. Therefore, in the arc welding apparatus, the influence of the magnetic blow of the arc can be eliminated by controlling the direction of the current of the electrode and the magnetic coil and the relative position of the electrode and the magnetic coil with respect to the deflection of the arc caused by the magnetic blow.

(2) In the arc welding apparatus according to (1), the electrode is disposed within a range of 1.5 times the entire length of the winding portion of the magnetic coil with a midpoint of the entire length of the winding portion as a center in the welding direction.

According to this arc welding apparatus, the position of the electrode is located between the pair of magnetic coils, and the electromagnetic force necessary for deflecting the arc can be secured with low electric power.

(3) In the arc welding apparatus according to (1) or (2), the coil exciting section makes a magnetic flux density generated by the electrode be 10mT to 90mT, and a ratio of a total current flowing through the ground connection section to the magnetic flux density is 1.5 to 60.0.

According to this arc welding apparatus, for example, when 150A of current flows through each electrode with one ground wire and two electrodes, the total current becomes 300A. Since the magnetic blow generated is stronger as the combined total current is larger, a large magnetic flux density is required to suppress the magnetic blow. Therefore, by setting the ratio of the total current to the magnetic flux density to 60.0 or less, shortage of the magnetic field does not occur, and by setting the ratio of the total current to the magnetic flux density to 1.5 or more, the increase in the outer diameter of the magnetic coil can be suppressed.

(4) In any one of the arc welding apparatuses (1) to (3), a gas suction portion for sucking ambient gas is provided between the electrodes of the plurality of electrodes.

According to this arc welding device, the instability of the arc of the leading electrode among the plurality of electrodes can be suppressed. For example, in welding in the vertical upward direction, the shielding gas of the trailing electrode rises along the groove, and the rising gas covers the periphery of the leading electrode as a gas involving the peripheral air, and as a result, it is possible to suppress the arc of the leading electrode from becoming unstable.

(5) In any one of the arc welding apparatuses (1) to (4), a shielding member for shielding a space around each of the plurality of electrodes is provided between the electrodes.

According to this arc welding device, the instability of the arc of the leading electrode among the plurality of electrodes can be suppressed. For example, in welding in the vertical direction, the shielding gas of the trailing electrode rises along the groove, and it is possible to suppress unstable arc of the leading electrode due to disturbance of the shielding gas of the leading electrode.

(6) In any one of the arc welding apparatuses (1) to (5), the control unit may move the magnetic coil in the welding direction.

According to this arc welding apparatus, each magnetic coil is movable by the coil moving mechanism. The magnetic coil moves in the welding direction, and thereby the direction of the electromagnetic force acting on the arc can be reversed.

(7) In any one of the arc welding apparatuses (1) to (6), the control unit reverses the excitation polarity of the magnetic coil.

According to this arc welding apparatus, the direction of the generated electromagnetic force can be easily reversed by reversing the direction of the current supplied to the magnetic coil and reversing the direction of the magnetic lines of the external magnetic field around the arc.

(8) In any one of the arc welding apparatuses (1) to (7), the plurality of electrodes are configured by non-consumable electrodes including two electrodes, and an inter-electrode distance between the two electrodes is 50mm to 400 mm.

According to this arc welding apparatus, the inter-electrode distance between the two electrodes is set to 50mm or more, so that the concentration of the arc interference and the input heat is eliminated, and the inter-electrode distance between the two electrodes is set to 400mm or less, so that the appearance of the weld bead is improved.

(9) The arc welding device according to (8), further comprising: a wire feeding head that feeds at least one filler wire toward the non-consumable electrode; a wire power source that independently applies a current to the filler wire; and a wire current adjustment unit that changes at least one of a current and a polarity applied to the filler wire.

According to this arc welding apparatus, the current and polarity of the filler wire are changed by the wire current adjustment unit, so that the magnetic field from the electrode can interfere with the arc. Therefore, the arc direction control can be assisted by the use of the magnetic coil together with the formation of the external magnetic field.

(10) An arc welding method in which two or more electrodes each including one or both of a non-consumable electrode and a consumable electrode are arranged along a welding direction, and a welding current is applied between the electrodes and a workpiece to generate an arc, wherein a pair of magnetic coils on both sides of the electrode, which is provided at least on an electrode arranged closest to a ground connection portion of the workpiece and which is disposed closest to the electrode, is excited to generate a magnetic flux, and an external magnetic field around the arc is changed according to a relative position between the electrode and the pair of magnetic coils and the magnetic flux from the magnetic coils.

According to this arc welding method, the magnetic coils are disposed on both the armpit sides of the electrode closest to the ground connection portion of the workpiece. The magnetic coil sandwiching the electrode is disposed in a posture in which an axis of the core is along a direction of the workpiece. The electrode becomes positive or negative, and a magnetic field is generated at the electrode itself. On the other hand, a current also flows through the magnetic coil sandwiching the electrode, and a magnetic field is generated. The arc is deflected by the magnetic field of the electrodes themselves, as well as the magnetic field of the individual magnet coils. The electromagnetic force deflecting the arc becomes stronger when the magnetic lines of force from the respective portions are aligned. That is, the direction of the electromagnetic force changes depending on the electrode, the direction of the current of the magnetic coil, and the relative positions of the electrode and the magnetic coil. Therefore, in the arc welding method, the direction of the arc can be controlled by controlling the direction of the current of the electrode and the magnetic coil and the relative position between the electrode and the magnetic coil. This can suppress arc interference and magnetic blow.

(11) A magnetic control device for arc welding, which controls the directionality of an arc generated by an electrode composed of a non-consumable electrode or a consumable electrode, wherein the magnetic control device for arc welding comprises: a magnetic coil having a pair of winding portions formed by winding a lead wire at each of front end portions of a U-shaped iron core; a coil moving mechanism that supports the magnetic coil movably in a welding direction while sandwiching the electrode between a pair of the winding portions; a coil exciting section that excites the magnetic coil to generate magnetic flux; and a control unit that changes an external magnetic field around the arc according to a relative position between the electrode and the pair of winding portions and a magnetic flux from the electrode and the pair of magnetic coils.

According to this magnetic control device for arc welding, a pair of magnetic coils is provided so as to sandwich a non-consumable electrode or a consumable electrode. Each magnetic coil has a core around which a wire is wound in a coil shape. The core may also be in the form of two separate rods or a horseshoe (U-shape). The magnetic coil is disposed in a posture in which the axis of the core is along the workpiece. The magnetic coil generates a magnetic field by flowing a current. On the other hand, the electrode sandwiched by the magnetic coil is also positive or negative, and a magnetic field is generated in the electrode itself. The arc is deflected by the magnetic field of the electrodes themselves and the magnetic field of the individual magnet coils. The electromagnetic force deflecting the arc becomes stronger when the magnetic lines of force coincide. The direction of the electromagnetic force changes depending on the electrode, the direction of the current of the magnetic coil, and the relative positions of the electrode and the magnetic coil. Therefore, in the arc welding magnetron device, the direction of the current of the electrode and the magnetic coil and the relative position between the electrode and the magnetic coil are controlled, whereby the arc can be controlled in the front, rear, left, and right directions.

(12) In the arc welding magnetic control device according to (11), the number of turns of the wire in the winding portion is 800 to 1600 turns, and a distance between the pair of winding portions is 80 to 200 mm.

According to this arc welding magnetic control device, the number of turns of the wire is set to 800 or more so that the magnetic field does not become insufficient, and the number of turns of the wire is set to 1600 or less so that the outer diameter of the magnetic coil does not become large, under the same iron core, the same wire diameter, and the same voltage. Further, interference between the magnetic coil and the electrode can be suppressed by setting the distance between the pair of winding portions to 80mm or more, and a shortage of the magnetic field is less likely to occur by setting the distance between the pair of winding portions to 200mm or less. This enables the arc to be effectively directed.

Claims

1. An arc welding apparatus in which two or more electrodes each including one or both of a non-consumable electrode and a consumable electrode are arranged along a welding direction, and a welding current is applied between the electrodes and a workpiece to generate an arc,

the arc welding device is provided with:

a pair of magnetic coils provided on both the axilla sides of at least an electrode disposed closest to the ground connection portion of the workpiece, among the plurality of electrodes, with the electrode interposed therebetween;

a control unit that changes an external magnetic field around the arc according to a relative position between the electrode and the pair of magnetic coils and a magnetic flux from the electrode and the pair of magnetic coils,

the axis of the magnet coil is parallel or inclined with respect to the weld face of the workpiece,

the electrode is disposed within a range of 1.5 times the total length of the winding portion of the magnetic coil with the midpoint of the total length of the winding portion as the center in the welding direction.

2. The arc welding apparatus according to claim 1,

the coil exciting section causes the magnetic flux density generated by the electrode to be 10mT to 90mT,

the ratio of the total current flowing through the ground connection part to the magnetic flux density is 1.5 to 60.0.

3. The arc welding apparatus according to claim 1,

a gas suction unit for sucking ambient gas is provided between the electrodes of the plurality of electrodes.

4. The arc welding apparatus according to claim 1,

a shielding member that shields a surrounding space of each of the electrodes is provided between the electrodes of the plurality of electrodes.

5. The arc welding apparatus according to claim 1,

the control portion moves the magnetic coil in the welding direction.

6. The arc welding apparatus according to claim 1,

the control unit reverses the excitation polarity of the magnetic coil.

7. The arc welding apparatus according to any one of claims 1 to 6,

the plurality of electrodes are composed of non-consumable electrodes including two electrodes, and the inter-electrode distance between the two electrodes is 50mm to 400 mm.

8. The arc welding apparatus according to claim 7,

the arc welding device is provided with:

a wire feeding head that feeds at least one filler wire toward the non-consumable electrode;

a wire power source that independently applies a current to the filler wire; and

and a wire current adjustment unit that changes at least one of a current and a polarity applied to the filler wire.

9. An arc welding method in which two or more electrodes each including one or both of a non-consumable electrode and a consumable electrode are arranged along a welding direction, and a welding current is applied between the electrodes and a workpiece to generate an arc,

a pair of magnetic coils provided on both the arm sides of at least one of the plurality of electrodes disposed closest to the ground connection portion of the workpiece are excited to generate a magnetic flux,

an external magnetic field around the arc is changed according to a relative position of the electrode and the pair of magnetic coils and a magnetic flux from the magnetic coils,

10. A magnetic control device for arc welding, which controls the directionality of an arc generated by an electrode composed of a non-consumable electrode or a consumable electrode,

the magnetic control device for arc welding is provided with:

a magnetic coil having a pair of winding portions formed by winding a lead wire at each of front end portions of a U-shaped iron core;

a coil moving mechanism that supports the magnetic coil movably in a welding direction while sandwiching the electrode between a pair of the winding portions;

a coil exciting section that excites the magnetic coil to generate magnetic flux; and

a control unit that changes an external magnetic field around the arc according to a relative position between the electrode and the pair of winding portions and a magnetic flux from the electrode and the pair of magnetic coils,

11. The arc welding magnetron apparatus according to claim 10, wherein,

the number of turns of the wire of the winding part is 800-1600 turns,

the distance between the pair of winding parts is 80 mm-200 mm.