阅读说明：本技术 多电极埋弧焊接方法以及焊接装置 (Multi-electrode submerged arc welding method and welding device ) 是由 山崎亮太 迎井直树 铃木励一 于 2018-06-13 设计创作，主要内容包括：在角焊焊接用的多电极埋弧焊接方法以及焊接装置中,先行极(4)的极性是相反极性,先行极4的喷枪角度θ<Sub>L</Sub>是5°≤θ<Sub>L</Sub>≤45°,后行极(5)的喷枪角度θ<Sub>T</Sub>是40°≤θ<Sub>T</Sub>≤60°,且是θ<Sub>L</Sub>≤θ<Sub>T</Sub>,先行极(4)的电流密度J<Sub>L</Sub>[A/mm<Sup>2</Sup>]和电弧电压V<Sub>L</Sub>[V]满足5.0≤J<Sub>L</Sub>/V<Sub>L</Sub>≤18.5的条件。由此,即使是母材的板厚厚的情况,也能通过得到充分的深熔深效果来减低气孔缺陷,且能在通过熔融金属的稳定化保持合适的焊道形状的情况下实施高速焊接。(In a multi-electrode submerged arc welding method and welding device for fillet welding, the polarity of a leading electrode (4) is opposite, and the spray gun angle theta of the leading electrode (4) L Theta is more than or equal to 5 degrees L Not more than 45 degrees, and the angle theta of the spray gun of the back row pole (5) T Theta is not less than 40 degrees T Not more than 60 degrees and is theta L ≤θ T Current density J of the leading electrode (4) L [A/mm 2 ]And arc voltage V L [V]J is more than or equal to 5.0 L /V L The condition is less than or equal to 18.5. Thus, even when the thickness of the base metal is thick, the porosity defect can be reduced by obtaining a sufficient deep penetration effect, and the appropriate bead shape can be maintained by stabilizing the molten metalAnd (5) implementing high-speed welding.)

1. A multi-electrode submerged arc welding method for fillet welding using 2 electrodes of a leading electrode and a trailing electrode,

the polarity of the leading pole is the opposite polarity,

angle theta of the spray gun of the leading electrode_LTheta is more than or equal to 5 degrees_LNot more than 45 degrees, and the angle theta of the spray gun of the backward pole_TTheta is not less than 40 degrees_TNot more than 60 degrees and is theta_L≤θ_T，

Current density J of the leading electrode_L[A/mm²]And arc voltage V_L[V]The condition of the formula (1) is satisfied,

5.0≤J_L/V_Lless than or equal to 18.5 … formula (1).

2. A multi-electrode submerged arc welding method for fillet welding having 3 or more electrodes, characterized in that,

the polarity of the leading pole positioned most forward with respect to the welding direction is the opposite polarity,

angle theta of the spray gun of the leading electrode_LTheta is more than or equal to 5 degrees_L45 DEG or less, and a lance angle theta of the rearmost trailing pole with respect to the welding direction_TTheta is not less than 40 degrees_TNot more than 60 degrees and is theta_L≤θ_T，

Current density J of the leading electrode_L[A/mm²]And arc voltage V_L[V]Satisfying condition を of formula (1),

5.0≤J_L/V_Lless than or equal to 18.5 … formula (1).

3. The multi-electrode submerged arc welding method according to claim 1 or 2,

the welding speed S [ cm/min ] satisfies the condition of the formula (2),

5.0≤J_L/V_L100/S … formula (2).

4. The multi-electrode submerged arc welding method according to claim 1 or 2,

the wire diameter R of the leading electrode_LAnd the protruding length E of the leading electrode_LThe condition of the formula (3) is satisfied,

6.0≤E_L/R_Lformula (3) is less than or equal to 12.5 ….

5. The multi-electrode submerged arc welding method according to claim 1 or 2,

and setting the welding current of the back row electrode as alternating current.

6. The multi-electrode submerged arc welding method according to claim 1 or 2,

the wire diameter R of the leading electrode_LIs 1.2 to 2.0 mm.

7. The multi-electrode submerged arc welding method according to claim 1 or 2,

the diameter R of the welding wire of the back pole_TIs 1.6 to 6.4 mm.

8. The multi-electrode submerged arc welding method according to claim 1 or 2,

the wire diameter R of the leading electrode_LAnd a wire diameter R of the trailing pole_TThe relation of the formula (4) is satisfied,

0.8≤R_T/R_L… formula (4).

9. A welding apparatus, characterized in that welding is performed by the multi-electrode submerged arc welding method according to claim 1 or 2.

Technical Field

The present invention relates to a multi-electrode submerged arc welding method and a welding apparatus, and more particularly, to a multi-electrode submerged arc welding method and a welding apparatus for feeding 2 or more electrode wires into a granular flux for welding.

Background

In horizontal fillet welding in the field of shipbuilding, it is required to reduce the blow hole defect due to vaporization of an anticorrosive coating. For example, patent document 1 discloses a tandem gas shielded arc welding method for horizontal fillet welding in which a solid wire is used for a leading electrode and a Flux Cored Wire (FCW) is used for a trailing electrode. In patent document 1, the deep penetration effect is obtained, and the gasified rust preventive paint can be discharged to reduce the defect of the blowholes.

Further, as tandem submerged arc welding in which 2 electrode wires are fed into a granular flux for welding to perform welding, for example, patent document 2 discloses: the welding method is characterized in that various welding conditions such as the diameter of an electrode wire, the current, the voltage, the inter-electrode distance and the action angle of a leading electrode and a trailing electrode are set to be specific ranges, and the welding is carried out at a horizontal fillet attitude with a welding speed of 160-200 cm/min by using a molten flux with a basicity within a specific range.

Patent document 3 also discloses a large fillet length horizontal fillet submerged arc welding method in which welding is performed by setting the diameters of the electrode wires of the leading electrode and the trailing electrode, the angles formed by the respective electrode wires and the welding line, the inter-electrode distance, and the like in specific ranges.

Disclosure of Invention

Problems to be solved by the invention

The method described in patent document 1 is a tandem gas shielded arc welding method using a shielding gas. In order to sufficiently ensure the deep penetration effect for an object having a large plate thickness, it is necessary to increase the values of the current and voltage of the leading electrode and the trailing electrode. However, in the tandem gas-shielded arc welding method, if the values of the current and the voltage are excessively increased, a drop of a weld bead due to an increase in the amount of molten metal, a change in the arc length due to a phenomenon of molten metal flowing between the leading electrode and the trailing electrode, and an arc instability due to an excessive electromagnetic force generated during welding occur. Therefore, in the method described in patent document 1, the effect of the deep penetration is insufficient for the object having a plate thickness of more than 12mm due to the influence of the arc length fluctuation and the arc instability, and therefore, the suppression of the blow hole defect is not considered. Further, the tandem gas-shielded arc welding method described in patent document 1 requires the use of a solid wire for the leading electrode and the use of FCW for the trailing electrode, and is not suitable for another welding method in which the conditions of the type of wire and the wire diameter are changed.

In addition, the method described in patent document 1 has the following problems: in order to achieve both the stability of the arc and the stability of the molten metal between the leading electrode and the trailing electrode and to ensure a good bead shape and a sufficient deep penetration effect, the welding speed is practically limited to about 120 cm/min.

In addition, in the horizontal fillet tandem submerged arc welding method described in patent document 2, although high-speed welding at 160 to 200cm/min is possible, the target steel sheet is a steel sheet having a thickness of less than 8mm such as a boiler wall, and a sufficient deep penetration effect cannot be obtained for a thick steel sheet having a thickness of more than 12mm, and the porosity defect cannot be reduced.

Further, in the horizontal fillet submerged arc welding method described in patent document 3, the diameter of the leading electrode wire is set to 1.2 to 2.0mm, and the inclination angle of the leading electrode from the vertical plate is set to less than 40 °, so that the deep penetration effect cannot be obtained appropriately, and the porosity defect cannot be reduced.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a multi-electrode submerged arc welding method and a welding apparatus for fillet welding, which can reduce the void defects by obtaining a sufficient deep penetration effect even when the thickness of a base material is thick, and can perform high-speed welding while maintaining an appropriate bead shape by stabilizing a molten metal.

Means for solving the problems

The above object of the present invention is achieved by the following configuration.

That is, the multi-electrode submerged arc welding method is a multi-electrode submerged arc welding method for fillet welding using 2 electrodes of a leading electrode and a trailing electrode, the polarity of the leading electrode being opposite polarity (DCEP), the torch angle θ of the leading electrode being equal to the torch angle θ_LTheta is more than or equal to 5 degrees_LNot more than 45 degrees, and the angle theta of the spray gun of the backward pole_TTheta is not less than 40 degrees_TNot more than 60 degrees and is theta_L≤θ_TCurrent density J of the leading electrode_L[A/mm²]And arc voltage V_L[V]The condition of formula (1) is satisfied.

5.0≤J_L/V_LLess than or equal to 18.5 … type (1)

The multi-electrode submerged arc welding method is a multi-electrode submerged arc welding method for fillet welding having 3 or more electrodes, in which the polarity of a leading electrode positioned at the forefront with respect to the welding direction is opposite, and the lance angle θ of the leading electrode is set to be larger than the welding angle θ of the leading electrode_LTheta is more than or equal to 5 degrees_L45 DEG or less, and a lance angle theta of the rearmost trailing pole with respect to the welding direction_TTheta is not less than 40 degrees_TNot more than 60 degrees and is theta_L≤θ_TCurrent density J of the leading electrode_L[A/mm²]And arc voltage V_L[V]The condition of formula (1) is satisfied.

5.0≤J_L/V_LLess than or equal to 18.5 … type (1)

In the above-mentioned multi-electrode submerged arc welding method with 2 electrodes or 3 or more electrodes, the welding speed S [ cm/min ] may satisfy the condition of formula (2).

5.0≤J_L/V_L100/S … formula (2)

Further, the multi-electrode submerged arc welding method using 2 electrodes or 3 or more electrodesIn the method, the wire diameter R of the leading electrode may be_LAnd the protruding length E of the leading electrode_LThe condition of formula (3) is satisfied.

6.0≤E_L/R_LLess than or equal to 12.5 … type (3)

In the above-described multi-electrode submerged arc welding method with 2 electrodes or 3 or more electrodes, the welding current of the trailing electrode may be an alternating current.

In the above-mentioned multi-electrode submerged arc welding method with 2 electrodes or 3 or more electrodes, the wire diameter R of the leading electrode may be set to be smaller than the wire diameter R of the leading electrode_LIs 1.2 to 2.0 mm.

In the above-mentioned multi-electrode submerged arc welding method with 2 electrodes or 3 or more electrodes, the wire diameter R of the trailing electrode may be set to be smaller than the wire diameter R of the trailing electrode_TIs 1.6 to 6.4 mm.

In the above-mentioned multi-electrode submerged arc welding method with 2 electrodes or 3 or more electrodes, the wire diameter R of the leading electrode may be set to be smaller than the wire diameter R of the leading electrode_LAnd a wire diameter R of the trailing pole_TThe relationship of the formula (4) is satisfied.

0.8≤R_T/R_L… type (4)

The welding apparatus of the present invention performs welding by the above-described multi-electrode submerged arc welding method.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the multi-electrode submerged arc welding method and welding apparatus for fillet welding according to the present invention, the deep penetration effect can be obtained by setting the polarity of the leading electrode (the electrode positioned at the forefront with respect to the welding direction in the case of 3 electrodes or more) to the opposite polarity, and the torch angle θ of the leading electrode is set to the opposite polarity_LTheta is set to be more than or equal to 5 DEG_LNot more than 45 degrees, and can lead the melting depth direction to face the butt joint part of the steel plate, and can obtain more proper melting depth. Further, the lance angle θ of the trailing electrode (the electrode positioned farthest forward in the welding direction in the case of 3 electrodes or more) is set to be larger than the lance angle θ_TTheta is set to be more than or equal to 40 DEG_TIs less than or equal to 60 degrees and is set as theta_L≤θ_TThe weld bead formed by the leading electrode can be flattened and shaped into a good weld bead shape. Further, passing current density J_L[A/mm²]And arc voltage V_L[V]J is more than or equal to 5.0_L/V_LUnder the condition of less than or equal to 18.5, the concentration of the electric arc is improved, the electric arc is generated in the state that the welding wire is drilled into the inner side of the surface of the steel plate, and further the deep melting effect can be obtained by the proper welding wire melting amount. In the case of 3 electrodes or more, the electrode located in the middle is used to adjust the amount of molten wire to an appropriate range. Therefore, the electrode positioned in the middle does not directly affect the deep penetration effect and the bead shaping effect, and therefore, the lance angle, the welding conditions, and the like are not particularly limited.

Thus, even when the thickness of the base metal is large, the blowhole defect can be reduced by obtaining a sufficient deep penetration effect, and high-speed welding can be performed while maintaining an appropriate bead shape by stabilizing the molten metal.

Drawings

Fig. 1 is a schematic front view for explaining submerged arc welding with 2 electrodes in a multi-electrode submerged arc welding method according to an embodiment of the present invention.

Fig. 2 is a schematic side view for explaining the 2-electrode submerged arc welding method shown in fig. 1.

Fig. 3 is a schematic front view for explaining submerged arc welding having 3 or more electrodes in the multi-electrode submerged arc welding method according to the embodiment of the present invention.

Fig. 4 is a schematic side view for explaining the multi-electrode submerged arc welding method shown in fig. 3.

Detailed Description

An embodiment for implementing the present invention is described in detail below with reference to the drawings. The present invention is not limited to the embodiments described below.

In the multi-electrode submerged arc welding method according to the present embodiment, the submerged arc welding method with 2 electrodes is as follows as shown in fig. 1 and 2: 2 welding wires (consumable electrodes) 40 and 50 constituting the leading electrode 4 and the trailing electrode 5 are fed into a granular flux 3 supplied from a feeder (not shown) to weld the base material constituted by the lower plate 1 and the upright plate 2.

Specifically, the welding wires 40 and 50 are inserted into the welding torch, protrude from the tip of each torch, and are positioned on the base material at a predetermined inter-electrode distance G and a predetermined torch angle θ, which will be described later_L、θ_TA given tilt angle configuration. Further, the space between the leading electrode 4 and the base material, the space between the trailing electrode 5 and the base material, and the space between the leading electrode 4 and the trailing electrode 5 are filled with the soldering flux 3, respectively.

The welding wires 40 and 50 of the leading electrode 4 and the trailing electrode 5 may be either a solid wire or an FCW, and the solid wire is not particularly limited, but is preferably used as the welding wire 40 of the leading electrode 4 in order to more suitably obtain the deep penetration effect. The welding wires 40 and 50 are applicable to even inexpensive solid welding wires that do not contain expensive elements such as rare earth elements. The soldering flux 3 is a general flux for fillet soldering.

The welding wires 40 and 50 of the leading electrode 4 and the trailing electrode 5 are connected to a welding power supply (not shown), respectively, and supply electric power of a predetermined arc voltage and welding current to the butting portion (the corner portion between the upper surface of the lower plate 1 and the side surface of the upright plate 2) with the lower plate 1 and the upright plate 2 as base materials. Thereby, arcs are generated between the leading electrode 4 and the base material and between the trailing electrode 5 and the base material, respectively, and the welding wires 40 and 50 of the leading electrode 4 and the trailing electrode 5 and the base material are melted by the arc heat to become molten metal 7 a. Further, the soldering flux 3 is melted on the molten metal 7a to form a molten slag 8 a. Then, when the leading electrode 4, the trailing electrode 5, and the feeder are moved forward in the welding direction X, the molten metal 7a and the molten slag 8a solidify behind them, and a weld bead (weld metal) 7b and a solidified slag 8b on the weld bead (weld metal) are formed.

Fig. 3 and 4 show submerged arc welding with 3 electrodes. In this case, the intermediate pole 6 is disposed between the leading pole 4 positioned furthest forward with respect to the welding direction and the trailing pole 5 positioned furthest rearward with respect to the welding direction, and the welding wire 60 constituting the intermediate pole 6 is also fed into the welding flux 3 together with the welding wires 40 and 50 to be welded. The welding wire 60 of the intermediate pole 6 may be either a solid wire or FCW.

In the present embodiment, various welding conditions are set so that, even when the thickness of the base metal is thick, a sufficient deep penetration effect can be obtained to reduce the pore defects such as dents and pores, and high-speed fillet welding can be performed while providing a good bead shape.

The following describes various welding conditions and reasons therefor.

[ lance angle θ of leading electrode 4 and trailing electrode 5_L、θ_T]

As shown in fig. 2, the lance angle is represented by an angle formed by the center line of the leading and trailing electrodes 4 and 5 (the center line of the projection which is the tip of the welding wires 40 and 50) and the upper surface of the lower plate 1. In the present embodiment, the lance angle θ of the leading electrode 4_LTheta is more than or equal to 5 degrees_LNot more than 45 degrees and the spray gun angle theta of the back row pole 5_TTheta is not less than 40 degrees_TIs less than or equal to 60 degrees and is set as theta_L≤θ_T. Even when the axial lower plate 1 is disposed at an angle to the horizontal plane with the weld line (the base material is inclined), the effect of the present invention can be obtained without the direction of action of gravity interfering with the effect of deep penetration.

The angle theta of the spray gun of the leading electrode 4_LThe reason why the angle is set to 5 ° or more and 45 ° or less is that the lance angle θ_LLess than 5 °, the weld beads 7b overlap, and not only become unsuitable as a shape, but also the welding wire 40 of the leading electrode 4 approaches the surface of the lower plate 1, and the arc point may become unstable.

In addition, if the lance angle θ_LIf the melting depth exceeds 45 degrees, the steel sheet may be deviated toward the lower plate 1 side, and the effect of the deep melting depth in the butt portion of the steel sheets may not be obtained, and the porosity defect may not be reduced.

Further, the lance angle θ as the leading electrode 4_LPreferably 20 DEG-theta_L≤35°。

Further, the lance angle θ passing through the trailing pole 5_TTheta is set to be more than or equal to 40 DEG_TThe convex shape of the weld bead 7b formed by the leading electrode 4 is flattened to a good weld bead shape at 60 DEG or less.

[ Tilt angles of leading electrode 4 and trailing electrode 5]

The inclination angle is represented by an angle formed by the center line of the leading electrode 4 and the trailing electrode 5 and a plane having the welding direction X as a normal. In the present embodiment, the inclination angles of the leading electrode 4 and the trailing electrode 5 with respect to the welding direction X are not particularly limited, but it is preferable to set the bead shapes so as to form a receding angle or an advancing angle of 0 ° or more and 15 ° or less, respectively, in consideration of the welding bead shape.

In addition, when the electrode is at a receding angle, the penetration tends to be deep, and when the electrode is at an advancing angle, the penetration tends to be shallow and the weld bead tends to be wide.

[ interelectrode distance G ]

The inter-electrode distance G, which is the distance between the electrodes, is not particularly limited, and is preferably 10 to 45 mm. By setting the interpolar distance G to 10mm or more, arc interference between electrodes is prevented and a suitable weld bead shaping effect can be obtained. Further, setting the inter-electrode gap distance G to 45mm or less is more effective in suppressing the size of the equipment and the occurrence of defective portions.

Diameter R of welding wire 40 of leading electrode 4 and trailing electrode 5_L、R_T]

Diameter R of welding wire 40 of leading electrode 4_LPreferably 1.2 to 2.0 mm. Diameter R of welding wire 40 of leading electrode 4_LIf the current is less than 1.2mm, the wire feeding speed must be excessively increased when the current is increased, and the feeder becomes large. On the other hand, the diameter R of the wire 40 of the leading electrode 4_LWhen the thickness exceeds 2.0mm, the current density J described later is increased_L[A/mm²]The value of (3) requires an increase in current, which leads to an increase in the amount of deposited metal. Therefore, the bead shaping effect of the trailing electrode 5 cannot be obtained appropriately, and appearance defects such as an increase in throat thickness and overlapping may occur.

Therefore, the wire diameter R of the leading electrode 4 is adjusted_LThe thickness of the welding bead is set to 1.2-2.0 mm, which can provide proper current, prevent the excessive welding wire feeding speed and the increase of deposited metal amount, and can further prevent the bad appearance in the proper welding bead shaping effect of the back electrode 5.

Further, the diameter R of the welding wire 50 of the trailing pole 5_TPreferably 1.6 to 6.4 mm. Thus, it is more suitableThe projection weld bead shape of the leading electrode 4 can be shaped while securing the deposition amount of the trailing electrode 5. In general gas-shielded arc welding, it is not considered to feed a welding wire having a diameter exceeding 2.0mm, and it is sometimes difficult to achieve both an appropriate bead shaping effect and a deposited metal amount.

Further, the diameter R of the welding wire 40 of the leading electrode 4 is adjusted_LDiameter R of welding wire 50 with trailing pole 5_TRatio of (R)_T/R_L) Preferably, the concentration is 0.8 or more. This ensures the total amount of deposited metal of the leading electrode 4 and the trailing electrode 5 appropriately, and enables the weld bead shaping effect of the trailing electrode 5 to be obtained more appropriately, thereby enabling a good weld bead shape to be formed.

If R is_T/R_LLess than 0.8, the diameter R of the welding wire 50 of the trailing electrode 5_TDiameter R of welding wire 40 with leading electrode 4_LThe diameter is excessively small, the arc is not sufficiently spread, and the bead shaping effect cannot be obtained appropriately.

R_T/R_LA more preferable range is 1.0. ltoreq.R_T/R_LLess than or equal to 5.0. That is, if the diameters of the leading electrode 4 and the trailing electrode 5 are made the same, the management of the welding wire becomes easy. In addition, the diameter R of the welding wire 50 of the trailing electrode 5 can be suppressed_TThe increase in the length of the leg due to the excessive diameter-enlarging of the electrode.

[ projection length E of leading electrode 4_L]

Further, the diameter R of the wire 40 of the leading electrode 4_LLength of projection E of welding wire 40 from leading electrode 4_LRatio of (E)_L/R_L) Preferably, it is set to 6.0. ltoreq.E_L/R_LLess than or equal to 12.5. If E_L/R_LLess than 6.0, protrusion length E_LIt is excessively short, and the tip may be fused at the welding end point or the like. In addition, if E_L/R_LOver 12.5, a projection length E_LThe length of the wire becomes excessively long, and the wire feeding speed needs to be increased due to the decrease in current, and the wire is likely to be misaligned in the penetration direction due to misalignment of the wire target position, which may result in deterioration of the bead appearance.

Therefore, the wire diameter R of the leading electrode 4 is set_LAnd of the leading electrode 4Length of projection E_LSatisfies E is more than or equal to 6.0_L/R_LThe condition of less than or equal to 12.5 prevents the welding of the contact tip at the welding end point, and can inhibit the deviation of the welding depth direction and the deterioration of the welding bead appearance.

[ polarities of leading electrode 4 and trailing electrode 5]

In addition, regarding the polarity of the leading electrode 4 and the trailing electrode 5 when electric power is supplied, it is preferable that the leading electrode 4 is set to the opposite polarity (DCEP) and the trailing electrode 5 is set to the Alternating Current (AC) in consideration of the point that the deep penetration effect is easily obtained and the discharge of bubbles is easy, the amount of deposited metal, and the shape of the weld bead. By setting the welding current of the trailing electrode 5 to ac, electromagnetic interference between the leading electrode 4 and the trailing electrode 5 during welding can be suppressed, and an appropriate bead shape can be obtained. When the number of electrodes is 3 or more, it is preferable that the welding current of the intermediate electrode 6 is AC in order to suppress electromagnetic interference with the leading electrode 4.

[ Current Density J of leading electrode 4_LAnd arc voltage V_LRatio of (J)_L/V_L)]

Current density J of power supplied to leading electrode 4_L[A/mm²]And arc voltage V_L[V]Is controlled by a control device not shown so as to satisfy J5.0 ≦ J_L/V_LThe condition is less than or equal to 18.5.

Satisfies the current density J of the leading electrode 4_L[A/mm²]And arc voltage V_L[V]Ratio of (J)_L/V_L) Under the condition of 5.0 to 18.5, the arc concentration is improved, the arc can be generated in a state that the welding wire 40 is drilled into the inner side of the surface of the steel plate, and the deep melting effect can be obtained by the appropriate welding wire melting amount.

If J_L/V_LBelow 5.0, the welding wire 40 cannot penetrate further inward than the surface of the steel plate to generate an arc, and the effect of deep penetration cannot be obtained. In addition, if J_L/V_LIf the amount of the molten wire exceeds 18.5, the amount of the molten wire of the leading electrode 4 excessively increases, and therefore the bead appearance cannot be sufficiently shaped by the trailing electrode 5, which makes the bead appearance unsuitable.

In addition, in order to obtain the deep penetration effect and the weld bead shaping effect more suitablyIt is desirable to set the current density J of the leading electrode 4_L[A/mm²]And arc voltage V_L[V]Ratio of (J)_L/V_L) Is set to J of 8.5 or less_L/V_L≤13.0。

In particular by setting the lance angle theta of the leading electrode 4 as described above_LTheta is set to be more than or equal to 20 DEG_LLess than or equal to 35 degrees, current density J of leading electrode 4_L[A/mm²]And arc voltage V_L[V]Ratio of (J)_L/V_L) Is set to J of 8.5 or less_L/V_LNot more than 13.0, the weld depth direction is concentrated on the butt portion of the base metal, and the weld bead shaping effect of the trailing electrode 5 can be obtained suitably, and a suitable weld bead can be obtained.

[ welding speed S ]

In addition, in order to maintain the deep melting effect, the welding speed S [ cm/min ]]Is controlled by a control device not shown so as to satisfy J5.0 ≦ J_L/V_L100/S conditions.

This makes it possible to make the bead appearance suitable by the deep penetration effect of the leading electrode 4 and the bead shaping effect of the trailing electrode 5. If J_L/V_LWhen the welding speed S is too high, the weld depth becomes shallow due to 100/S less than 5.0, and the defects such as undercut are likely to occur. Further, if the welding speed S is low, the amount of deposited metal increases excessively, the bead appearance deteriorates, and the construction efficiency decreases. For this purpose, priority is given to J_L/V_LThe upper limit of 100/S is set to 26.0.

As described above, according to the multi-electrode submerged arc welding method and the welding apparatus of the present embodiment, it is possible to reduce the void defects by the deep penetration effect by setting various welding conditions, and to perform fillet welding with a base material thickness of 20mm at a high speed up to a welding speed of 250cm/min, preferably 200 cm/min.

In particular, in the present embodiment, at least the polarity of the leading electrode 4 is set to the opposite polarity, and the lance angle θ of the leading electrode 4 is set to_LTheta is set to be more than or equal to 5 DEG_LNot more than 45 degrees, and the angle theta of the spray gun of the backward pole 5_TTheta is set to be more than or equal to 40 DEG_TIs less than or equal to 60 degrees and is set as theta_L≤θ_TMaking the current density J of the leading electrode 4_L[A/mm²]And arc voltage V_L[V]J is more than or equal to 5.0_L/V_LThe condition of less than or equal to 18.5 enables fillet welding with a deep penetration effect at a high speed while maintaining a good bead shape even when the thickness of the base metal is large.

The present invention is not limited to the above-described embodiments, and should be broadly construed in accordance with the claims. Further, the present invention can be modified and improved as appropriate based on these descriptions.

For example, the multi-electrode submerged arc welding method according to the present embodiment may be any of 1-cell welding in which 1 molten pool is formed by the leading electrode 4 and the trailing electrode 5, and 2-cell welding in which 2 molten pools are formed by the leading electrode 4 and the trailing electrode 5. In the welding method of the present invention, the welding may be performed by oscillation. Further, the welding posture is not particularly limited, and horizontal fillet welding may be adopted, or downward fillet welding may be adopted.