JPH10286670A - Method and device for electrogas arc welding of horizontal posture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a weld bead without incomplete fusion on the lower side of a groove and also a pushed back effect in the direction reverse to the welding direction of a preceding molten metal on the lower side of the groove by imparting a magnetic field to a welding arc from the groove surface in the direction toward the farthest-side and welding while generating a downward Lorentz's force in the welding arc. SOLUTION: An electric current 10 is formed in a welding arc 3 from a welding wire 2 to a molten pool 4. In this state, with a magnetic field 9a imparted vertically to the surface of a base material 6, a Lorentz's force is actuated so that the welding arc 3 is deflected downward, thereby melting the lower side of a groove 60 well and enabling a weld bead 63 to be obtained without incomplete fusion on the lower side of the groove 60. In addition, a pushed back action is generated in the counter-welding direction of the preceding molten metal on the lower side of the groove 60 by the arc pressure of the welding arc 3; hence, undercut is reduced in the upper part of the groove 60. In order to allow a magnetic field 9a, 9b to be imparted nearly vertically to the surface of the base material 6, an electromagnet is installed in a sliding copper patch 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal electrogas arc welding method and a welding apparatus for manufacturing a large steel structure such as a bridge.

[0002]

2. Description of the Related Art Conventionally, welding is an indispensable operation when manufacturing large steel structures such as chimneys, bridges, pressure vessels, and the like. In particular, since a large steel structure as described above cannot be easily inverted at the time of manufacture, welding in a horizontal (horizontal) posture is inevitable.
Electrogas arc welding, which can perform one-pass welding up to a maximum thickness of about 32 mm, is used in the vertical position. However, in the horizontal position, the molten metal is biased downward by the gravitational force due to gravity. Not applied, because normal bead shape cannot be obtained due to the problem.

[0003]

In the electrogas arc welding in the horizontal position, as described above, the molten metal is deflected to the lower side of the groove by the gravity, as shown in a schematic view from the surface of the base material 6 in FIG. In addition, due to the gravity of the molten metal itself, a leading A of the molten metal (molten pool) occurs below, and an undercut 61 occurs at the upper end of the groove 60, as is apparent from the cross-sectional view of FIG. Below the groove 60, the preceding molten metal 4 is wrapped under the welding arc 3, so that the fusion failure 62 is likely to occur and proper welding cannot be performed. In addition, 1 is a welding torch, 2 is a welding wire, 63 is a welding bead.

SUMMARY OF THE INVENTION In view of the above technical problems, the present invention provides an electrogas arc welding method in a horizontal position that does not cause welding defects such as poor fusion, undercut, and overlap, and that enables proper welding and high efficiency welding. And a welding device therefor.

[0005]

In order to solve this problem, according to the first aspect of the present invention, there is provided a magnetic field 9a substantially perpendicular to the surface of the base material 6, more specifically, from the welding wire 2 to the molten pool 4. For example, when the current 10 flows from left to right in the figure as shown in FIG.
A magnetic field 9a is applied to the welding arc 3 toward the depth side from the surface 0, and welding is performed while generating a downward (gravity direction) Lorentz force 11a to the welding arc 3.

The operation of the present invention will be described with reference to FIG. 3, which is a schematic view showing the downward deflecting operation of the welding arc 3. As shown in FIG.
, A current 10 is formed toward the molten pool 4. In this state, by applying a magnetic field 9a in a direction perpendicular to the surface of the base material 6 and causing the Lorentz force 11a to deflect the welding arc 3 downward (in the direction of gravity), the lower side of the groove 60 is well formed. Since it is melted, it is possible to obtain a weld bead 63 without a fusion defect below the groove 60.
In addition, the arc pressure of the welding arc 3 causes the pre-melted metal to be pushed back in the anti-welding direction shown by A in FIG. 9 below the groove 60, thereby reducing the undercut 61 above the groove 60. Is also obtained.

A second aspect of the present invention is to provide a case where the magnetic field 9 'is substantially perpendicular to the surface of the base material 6, more specifically, when the current 10 spreads radially near the front surface of the molten pool as shown in FIG. In the above, welding is performed while applying a magnetic field 9a ′ to the molten pool 4 in the depth direction from the surface of the groove 60 to generate a Lorentz force 11a ′ in the anti-welding direction (push-back) on the molten pool 4. Features.

The operation of the present invention will be described with reference to a schematic diagram showing the action of pushing back the molten metal shown in FIG. 4. As shown in FIG. 4, near the front surface of the molten pool, a current 10 spreading radially is generated. Is formed. By applying a magnetic field 9a 'in a direction substantially perpendicular to the base material 6 and causing the Lorentz force 11a' to act to push back the molten metal in the anti-welding direction, welding without an undercut 61 above the groove 60 is achieved. Bead 63 can be obtained.

According to a third aspect of the present invention, a magnetic field 9b in a direction substantially perpendicular to the surface of the base material 6, more specifically, a current 10 in a substantially unidirectional direction in the molten pool 4, for example, as shown in FIG. When flowing toward the right side, a magnetic field 9 b is applied to the molten pool 4 from the back side of the groove 60 toward the surface, and an upward (anti-gravity direction) Lorentz force 11 b is generated in the molten pool 4. It is characterized by welding.

The operation of the present invention will be described with reference to the schematic diagram of FIG.
As shown in FIG. 2, a current 10 in one direction is formed in the molten pool 4. By applying a magnetic field 9b in a direction substantially perpendicular to the base material 6 and causing the Lorentz force 11b to act in the lifting direction of the molten pool 4, a weld bead 63 without an undercut 61 above the groove 60 can be obtained. it can.

A fourth aspect of the present invention relates to a combination of the first to third aspects of the present invention.
Magnetic fields 9a, 9a ', 9b substantially perpendicular to the surface are applied to the welding arc 3 and the molten pool 4, respectively, to apply a downward (gravitational) Lorentz force 11a to the welding arc 3 and to the molten pool 4. Welding is performed while generating a Lorentz force 11a ′ in the anti-welding direction (push-back) and a Lorentz force 11b in the upward direction (anti-gravity direction). Thus, welding defects such as poor fusion, undercut 61, and overlap do not occur, and proper welding and high-efficiency welding can be performed.

The invention according to claim 5 is characterized in that a part of the welding current is diverted to the vicinity of the welded portion in order to make the current flowing in the molten pool 4 unidirectional, whereby the effect of the present invention described above is reduced. Further increase. The diverting position in the vicinity of the welded portion is preferably obtained from an additional wire inserted into the molten pool 4 and / or a sliding copper abutment.

A seventh aspect of the present invention relates to a preferred apparatus for performing the above-described electrogas arc welding method, and comprises a magnetic field 9 substantially perpendicular to the surface of the base material 6.
magnetic field generating means 13a, 13 for providing a, 9a ', 9b
a ′, 13b, at least one magnetic field generating means is provided, and the magnetic field generating means 13a, 13a ′,
13b and the current flowing through the weld pool and the arc, the Lorentz force 11a downward (in the direction of gravity)
And / or Lorentz force 11a ′ in the anti-welding direction (push-back) and / or Lorentz force 11b in the molten pool is directed upward (anti-gravity direction). The three types of Lorentz force and the number of magnetic field generating means do not necessarily have to correspond one-to-one.
A plurality of the three Lorentz forces may be generated by one magnetic field generating means.

A magnetic field 9 substantially perpendicular to the surface of the base material 6
As means for applying a to the welding arc 3 or the molten pool 4, a magnet body (permanent magnet, electromagnet) is preferably installed on the sliding copper abutment as described in claim 8, but is not limited thereto. Instead, a magnet body may be independently arranged near the welding arc 3 or near the molten pool 4. In order to effectively unidirectionalize the current 10 flowing in the molten pool 4, a diverting means for diverting a part of the welding current to the vicinity of the welded portion is provided, and the diverting means is used. The current flowing through the pond 4 may be made unidirectional.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. It's just

FIG. 1 shows an embodiment of an electrogas arc welding method in a horizontal position according to an embodiment of the present invention and a welding apparatus therefor. Reference numeral 7 denotes a DC welding power source, and a welding wire 2 is provided on the plus side of the welding power source 7. The base metal 6 is connected to the minus side, and a welding arc 3 is generated between the welding wire 2 protruding from the welding torch 1 and the base material 6, and the base material 6 is melted by this arc heat. The molten pool 4 is composed of a sliding copper metal 5 and a base metal 6.
Is formed in a closed space.

On the other hand, in order to be able to add magnetic fields 9a, 9a ', 9b in a direction substantially perpendicular to the surface of the base material 6, an electromagnet (or a permanent magnet) 13A,
13B is installed. The electromagnet 13A has a magnetic field 9a, 9a '.
And the electromagnet 13B can apply the magnetic field 9b. The electromagnets 13A and 13B are iron cores 14a,
The coils 16a and 16b are wound around 14b, and the electromagnet 13A is arranged so that the center of the iron core 14a is located near the arc 3, and the electromagnet 13B is arranged so that the center of the magnetic field is located near the molten pool 4. The positive and negative directions (NS directions) of the magnetic fields 9a and 9b are directed toward the back from the surface of the groove 60 in one electromagnet 13A on the welding arc 3 side and open in the other electromagnet 13B on the molten pool 4 side. The magnetic field lines (NS) are biased toward the front side from the back side of the tip 60.

Next, Lorentz force 1 generated in welding arc 3
1a will be described. As shown in FIG.
Inside, a current 10 is formed from the welding wire 2 toward the molten pool 4 from the left side to the right side in the figure. In this state, the one electromagnet 13A causes the magnetic field 9a to extend in the direction perpendicular to the surface of the base material 6 and the NS direction to the depth side from the surface of the groove 60.
Is added, the Lorentz force 11a can act to deflect the welding arc 3 downward (in the direction of gravity) according to Fleming's left-hand rule. As a result, the lower side of the groove 60 is melted well, so that a weld bead 63 without the fusion defect 62 below the groove 60 can be obtained. Further, the groove 60 due to the arc pressure of the welding arc 3 is formed.
A pushback action of the lower molten metal in the anti-welding direction shown by A in FIG. 9 on the lower side also occurs, whereby the effect of reducing the number of undercuts 61 above the groove 60 can be obtained.

Next, the Lorentz force 11b generated in the molten pool 4
Will be described. As shown in FIG. 4, near the front surface of the molten pool 4, a current 10 that spreads radially is formed.
In this state, when the magnetic field 9a 'is applied to the molten pool 4 in the NS direction toward the depth side from the surface of the groove 60, the Lorentz force 11a' is applied to the molten pool 4 in the anti-welding direction (pushing direction) according to Fleming's left-hand rule. (Return), and a push-back action occurs in the direction opposite to the welding direction of the preceding molten metal, so that a weld bead 63 without the undercut 61 above the groove 60 can be obtained. Further, as shown in FIG. 5, a current 10 is formed in the molten pool 4 in a generally one direction from the left side to the right side in the figure. In this state, the other electromagnet 1
When the magnetic field 9b is applied in a direction perpendicular to the surface of the base material 6 by 3B and the NS direction is applied from the back side of the groove 60 toward the surface side,
According to Fleming's left-hand rule, the weld bead 63 without the undercut 61 at the top of the groove 60 is obtained by the Lorentz force 11b acting on the weld pool 4 upward (anti-gravity direction) in the direction in which the weld pool 4 is lifted. Can be.

In this embodiment, the appropriate welding condition ranges are welding current 200 to 400 A, arc voltage 18 to
38V, welding speed 10-20cm / min, magnetic flux density 4
00 to 800 Gauss. Regarding the above condition range, the welding current is a range in which droplet transfer can be performed stably, the arc voltage is a range in which the arc can be stably maintained in the welding current range, and the welding speed is a groove 60 space in the welding current range. The range in which the welding amount filling the space is balanced, and the magnetic flux density are the ranges in which the electromagnetic force required to improve the shape of the bead 63 can be generated and the arc can be stably maintained. The appropriate welding condition range can be appropriately changed depending on the diameter and material of the welding wire 2 to be used, the shape and material of the base material 6, and the like.

FIG. 2 shows an electrogas arc welding apparatus in a horizontal position showing a configuration in which part of the welding current is diverted to the sliding copper abutment 5 in addition to the configuration of FIG.
A shunting device 8 is provided on the minus terminal side of the above, and a part of the welding current flowing through the base material 6 is diverted to the sliding copper abutment 5. According to such a configuration, the current 10 flowing through the molten pool 4 is made more unidirectional due to the branch current to the sliding copper abutment 5, whereby the strength of the Lorentz force 11a is further improved, and the effect of FIG. 1 is enhanced. .

FIG. 8 shows an electrogas arc welding apparatus in a horizontal position showing a configuration in which a part of the welding current is diverted to an additional wire inserted into the molten pool 4 in addition to the configuration of FIG. A flow dividing device 8 is provided on the minus terminal side, and a part of the welding current flowing through the base material 6 is diverted to the additional wire 15 inserted into the molten pool 4. In this case, the oscillating copper abutment 5 had a shape in which a part of the wire was punched out so that the addition wire 15 could be inserted into the molten pool 4. According to this configuration, when a part of the welding current is diverted to the additional wire 15 inserted into the molten pool 4, the current flowing through the molten pool 4 is further unidirectionalized as compared with FIG. The strength was further improved than in FIG. 2, and an effect stronger than that in FIG. 2 was obtained.

[0023]

As described above, according to the first, fourth and seventh aspects of the present invention, when performing the electrogas arc welding in the horizontal position, the welding arc, the welding current flowing in the molten pool, and the welding arc are not affected. By applying a perpendicular magnetic field to the base material to generate a downward (gravity direction) Lorentz force, the welding arc is deflected downward (gravity direction) and the lower side of the groove is melted well, The welding bead having no fusion failure on the lower side of the groove can further obtain an effect of pushing back the molten metal on the lower side of the groove in the welding direction by the arc pressure of the welding arc. Also,
According to the second, fourth and seventh aspects of the present invention, a magnetic field in the vertical direction is applied to the base material so as to generate a Lorentz force in the anti-welding direction (push-back) with respect to the front of the molten pool. Due to the effect of pushing back the molten metal in the anti-welding direction, a weld bead having no undercut at the top of the groove can be obtained.

According to the third, fourth and seventh aspects of the present invention, a perpendicular magnetic field is applied to the base material so as to generate an upward (anti-gravity) Lorentz force on the molten pool. In addition, a weld bead having no undercut at the upper part of the groove can be obtained by the effect of lifting molten metal.

According to the fifth, sixth and ninth aspects of the invention, the current flowing through the molten pool is made more unidirectional, so that the strength of the Lorentz force is further improved, and the effect of the invention is enhanced.

Further, according to the present invention, a magnetic field substantially perpendicular to the surface of the base material can be applied to the welding arc or the molten pool with a simple structure.

[Brief description of the drawings]

FIG. 1 is a connection circuit diagram of an electrogas arc welding apparatus according to a first embodiment of the present invention.

FIG. 2 is a connection circuit diagram of an electrogas arc welding apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a downward deflection action of a welding arc in the present invention.

FIG. 4 is a schematic view showing a push-back action of a preceding molten metal in the present invention.

FIG. 5 is a schematic view showing a lifting action of a molten metal in the present invention.

FIG. 6 is a sectional view of a weld bead showing a defect of the conventional method.

FIG. 7 is a plan view and a front sectional view illustrating an example of a magnetic field generating unit according to the first to third embodiments of the present invention.

FIG. 8 is a connection circuit diagram of an electrogas arc welding apparatus according to a second embodiment of the present invention.

FIG. 9 is a schematic view of a molten pool shape viewed from a base material surface side for explaining a problem of the conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding torch 2 Welding wire 3 Welding arc 4 Weld pool 5 Sliding copper equivalent 6 Base metal 7 Welding power supply 9a, 9a ', 9b Magnetic field 10 Current

Claims (9)

[Claims] In an electrogas arc welding in a lateral position, a magnetic field substantially perpendicular to a surface of a base material is applied to a welding arc, and welding is performed while generating a downward (gravity direction) Lorentz force on the welding arc. Characteristic welding method. 2. In electrogas arc welding in a horizontal position, a magnetic field in a direction substantially perpendicular to the surface of a base material is applied to a weld pool to generate a Lorentz force in an anti-welding direction (push-back) in the weld pool. Welding method characterized by performing. 3. In electrogas arc welding in a horizontal position, a magnetic field in a direction substantially perpendicular to the surface of a base material is applied to a molten pool, and welding is performed while generating an upward (anti-gravity direction) Lorentz force in the molten pool. A welding method characterized in that: 4. In the electrogas arc welding in a horizontal position, a magnetic field substantially perpendicular to a surface of a base material is applied to a molten pool to generate a downward (gravity direction) Lorentz force in a welding arc and / or A welding method characterized in that welding is performed while generating a Lorentz force in an anti-welding direction (push-back) in a pond and / or generating an upward (anti-gravity direction) Lorentz force in a molten pool. 5. The welding method according to claim 1, wherein a part of the welding current is diverted to the vicinity of the welded portion in order to make the current flowing in the molten pool unidirectional. 6. The welding method according to claim 5, wherein the branching position near the welded portion is an additional wire or / and a sliding copper abutment inserted into a molten pool. 7. An electro-gas arc welding apparatus configured to be capable of arc welding in a horizontal position, a first magnetic field generating means for applying a magnetic field in a substantially vertical direction to a base material surface for generating a downward Lorentz force on a welding arc; A second magnetic field generating means for applying a magnetic field in a direction substantially perpendicular to the surface of the base material for generating a Lorentz force in the weld pool in an anti-welding direction (push-back); and a Lorentz upward (anti-gravity direction) to the weld pool. At least one magnetic field generating means is provided among the third magnetic field generating means for applying a magnetic field in a direction substantially perpendicular to the surface of the base material for generating the force, and the first to third magnetic fields are provided by the provided magnetic field generating means. An electrogas arc welding apparatus characterized in that at least one of Lorentz forces can be generated. 8. The welding method according to claim 6, wherein a magnet body is provided on a sliding copper plate as means for applying a magnetic field substantially perpendicular to the surface of the base material to the welding arc or the molten pool. apparatus. 9. The welding apparatus according to claim 6, further comprising a diverting means for diverting a part of the welding current to the vicinity of the welded portion, wherein the diverting means makes the current flowing in the molten pool unidirectional.