JP2003053545A - Tandem arc welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain weld beads which are little in the amount of spatters to be produced, is good in the stability of a molten pool and is good in bead shapes in performing tandem arc welding by arranging a preceding electrode and trailing electrode consisting of solid wires for welding apart a prescribed inter- electrode distance in a welding direction, using a shielding gas having a gaseous composition of rich inert gas and forming the one molten pool with two arcs. SOLUTION: This tandem arc welding method comprises specifying the electrode projection length of the respective electrodes to 22 to 35 mm, the electrode angle formed by the two electrodes when viewed from a direction orthogonal with the welding direction to 1 to 9 deg., the inter-electrode distance to 10 to 29 mm and the sum of the welding current density of the preceding electrode and the welding current density of the trailing electrode to 500 to 1,000 A/mm<2> . A wire without copper plating which is coated with a K compound on the wire surface and is not subjected to copper plating on the wire surface is used as the solid wire for welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem arc welding method which is suitable for high-welding welding, produces a small amount of spatter, has good stability of the molten pool, and is capable of obtaining a good weld bead. Is.

[0002]

[Prior Art] Construction machinery manufacturers, bridge manufacturers, etc.
In the field of thick plate welding of steel, it is desired to further improve the efficiency and automation of welding in order to further reduce the cost. Therefore, in order to meet such a demand, it is conceivable to perform tandem arc welding by a gas shield welding method using a teaching reproduction type welding robot. This tandem arc welding is to perform welding by arranging a leading electrode and a trailing electrode made of a solid wire for welding with a predetermined electrode distance in the welding direction, and generating a gas shield arc from each electrode. Compared with arc welding with a single electrode, the amount of welding (the amount of wire fusion) is significantly larger, which enables highly efficient welding.

When performing tandem arc welding by using such a teaching reproduction type welding robot (hereinafter, simply referred to as a welding robot), in order to avoid the interference between the work and the torch, the welding robot has a wrist portion. As a torch to be mounted, a two-electrode integrated welding torch that can be downsized compared to mounting two single-electrode torches is used, and two electrodes are generated by making the inter-electrode distance between the leading electrode and the trailing electrode close to each other. It is necessary to form and weld one molten pool with the arc. As an example of the two-electrode integrated welding torch, a pair of torch bodies each having a welding wire passage, a shield gas supply passage, a power feeding passage and a cooling water passage are arranged at predetermined intervals in the welding direction, A pair of torch bodies are integrally surrounded and held by the tip end portions of the torch body by a jacket, and one shield gas is introduced in the tip direction of the tip (contact tip) attached to the tip body connected to each torch body. An example is one in which a shield gas nozzle is attached to the tip of the jacket.

However, conventionally, a leading electrode and a trailing electrode made of a solid wire for welding, which does not generate slag as compared with a flux-cored wire, are arranged at a predetermined distance in the welding direction in order to reduce the occurrence of spatter. Stabilize the molten pool when performing tandem arc welding by using a shield gas whose gas composition is rich in inert gas, shortening the distance between the electrodes, and forming one molten pool with two arcs at high current. It was difficult to obtain a weld bead having a good bead shape with a small amount of spatter generation.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to arrange a leading electrode and a trailing electrode made of a solid wire for welding with a predetermined electrode distance in the welding direction, and to make the gas composition inert gas rich. When a tandem arc welding is performed by using shield gas, shortening the distance between electrodes and forming a single molten pool with two arcs at high current, the amount of spatter is small, the molten pool is stable, and the bead shape is good. It is to provide a tandem arc welding method capable of obtaining a good welding bead.

[0006]

In order to achieve the above-mentioned object, the invention of claim 1 arranges a leading electrode and a trailing electrode made of a welding solid wire at a predetermined distance in the welding direction, The sum of the welding current density of the leading electrode and the welding current density of the trailing electrode when performing tandem arc welding by forming one molten pool with two arcs using a shield gas with an inert gas rich gas composition: 500 ~ 100
0 A / mm ² , electrode protrusion length of each electrode: 22 to 35 m
m, distance between electrodes: 10 to 29 mm, electrode angle formed by the both electrodes as viewed from a direction orthogonal to the welding direction: 1 to 9
Is a tandem arc welding method.

According to a second aspect of the present invention, in the tandem arc welding method according to the first aspect, the welding current of the leading electrode is A1, the welding voltage is V1, and the welding current of the trailing electrode is A1.
2. If the welding voltage is V2, (V1 / A1) / (V2
The value of / A2) is 0.78 to 0.97.

According to a third aspect of the present invention, in the tandem arc welding method according to the first or second aspect, when the shielding gas is Ar + CO ₂ , the mixing ratio of Ar is 55 to 96.
%, And in the case of Ar + He + (O ₂ or CO ₂ ), the mixing ratio of Ar + He is 55 to 96%.

A fourth aspect of the invention is the tandem arc welding method according to any one of the first to third aspects,
As a solid wire for welding, C: 0.01 to 0.13
% By weight, Si: 0.5 to 1.1% by weight, Mn: 0.5 to
2.2% by weight, Ti: 0.04 to 0.35% by weight, S:
0.001-0.030% by weight, O: 0.001-0.
020% by weight, the balance consisting of Fe and unavoidable impurities, and 1 K compound on the wire surface.
It is characterized by using a solid wire for welding, which is coated with ˜15 ppm (value converted to potassium) and has no copper plating on the wire surface.

A fifth aspect of the present invention is the tandem arc welding method according to any one of the first to third aspects,
As a solid wire for welding, C: 0.01 to 0.06
% By weight, Si: 0.6 to 0.9% by weight, Mn: 1.4 to
1.9% by weight, Ti: 0.12 to 0.28% by weight, S:
0.005-0.025% by weight, O: 0.003-0.
020% by weight, the balance consisting of Fe and unavoidable impurities, and 1 K compound on the wire surface.
It is characterized by using a solid wire for welding, which is coated with ˜15 ppm (value converted to potassium) and has no copper plating on the wire surface.

According to a sixth aspect of the invention, in the tandem arc welding method according to the fourth or fifth aspect, the solid wire for welding has MoS _{2 on the} wire surface of 10 kg of the wire.
It is characterized in that 0.01 to 0.50 g is applied per unit.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. In the tandem arc welding method of the present invention, the leading electrode and the trailing electrode made of a solid wire for welding are arranged with a predetermined distance between the electrodes in the welding direction, and two arcs are used by using a shield gas whose gas composition is inert gas rich. In 1
Each configuration in tandem arc welding performed by forming two molten pools and the reason for numerical limitation thereof will be described.

In the present invention, the solid wire for welding used as the leading electrode and the trailing electrode has a wire diameter of 1.2 mmφ which is most frequently used in gas shielded arc welding.
It is based on the use of the one. Further, FIG. 2 is a diagram for explaining the electrode protruding length L (wire protruding length), the electrode angle θ, and the interelectrode distance D in the tandem arc welding method of the present invention. As shown in the figure, the electrode protruding length L is the distance between the tip of the tip and the base material, and is the same for the leading electrode 3 and the trailing electrode 4. The electrode angle θ is an angle formed by the leading electrode 3 and the trailing electrode 4 when viewed from the direction orthogonal to the welding direction, and the inter-electrode distance D is the distance between the leading electrode 3 and the leading electrode 3 at a position separated by a length L from the tip of the tip. It is the distance from the trailing electrode 4. In addition, in FIG. 2, 1 is 2
Electrode integrated welding torch, 1a is the torch body for the leading electrode,
1b is a torch body for the trailing electrode, 1c is a jacket, 1d
Is a shield gas nozzle.

"Sum of welding current density of leading electrode and welding current density of trailing electrode: 500 to 1000 A / mm ² " When the sum of welding current densities is less than 500 A / mm ² , the welding amount is small and the efficiency is high. Cannot be achieved. On the other hand, 1000
If it is larger than A / mm ² , the force due to the plasma airflow of both electrodes acting on the molten pool (pool) formed between both electrodes is too strong, and the molten pool (pool) tends to be unstable. Therefore, the sum of the welding current densities of both electrodes is 500
˜1000 A / mm ² . More preferably, 600
~ 800 A / mm ² .

[The length L of the protruding electrode of each electrode: 22 to 35]
mm "electrode protrusion length (wire protrusion length) L is 22
If the length is shorter than mm, the radiant heat from the molten pool raises the chip temperature to 600 ° C or more and the wire feeding becomes unstable, resulting in frequent spattering. Also, when the arc is stopped, the welding wire is fed. The problem often occurs when the welding wire is fused to the hot tip when stopped. On the other hand, in order to achieve high welding, it is preferable that the electrode protruding length L is long, but if the electrode protruding length L exceeds 35 mm, the gas shielding property is deteriorated and blow holes are easily generated in the welding bead. Therefore, the electrode protrusion length L of each electrode is set to 22 to 35 mm. More preferably 2
It is 3 to 27 mm, and its optimum value is 25 mm. When the protruding length L is 25 mm, when the average welding current of both electrodes is 400 A, a high deposition amount of 20 kg / h can be obtained.

"Distance between electrodes D: 10 to 29 mm" When the distance D between the electrodes is smaller than 10 mm, the arcs generated from the leading electrode and the trailing electrode strongly attract each other and interfere with each other, and the melting formed between the two electrodes. The pool (bath pool) becomes unstable. On the other hand, if the inter-electrode distance D is larger than 29 mm, the stability of the molten pool (pool) is good, but the outer diameter of the shield gas nozzle of the two-electrode integrated welding torch mounted on the wrist of the welding robot becomes large. As a result, the application range of the welding robot is narrowed due to the interference between the torch and the work. Therefore, the distance D between the electrodes is set to 10 to 29 mm. More preferably 13-
It is 20 mm, and its optimum value is 15 mm.

[Electrode angle θ: 1 to 9 °] When the electrode angle θ is smaller than 1 °, the plasma of both electrodes is stabilized in the molten pool (melt pool) formed between both electrodes. The force due to the air flow does not sufficiently act, and the molten pool easily becomes unstable. On the other hand, when the electrode angle θ is larger than 9 °, the force due to the plasma airflow of both electrodes acts on the molten pool (melt pool) too much, and the molten pool (melt pool) is likely to become unstable. Therefore, the electrode angle θ is 1 to 9 °
And It is more preferably 3 to 7 °, and its optimum value is 5 °.

"The welding current of the leading electrode is A1, the welding voltage is V1, the welding current of the trailing electrode is A2, and the welding voltage is V2.
Then, the value of (V1 / A1) / (V2 / A2) is 0.
78 to 0.97 "When performing tandem arc welding by forming one molten pool with two arcs, stabilize and maintain the molten pool (bath pool) formed between both electrodes Therefore, as for the welding voltage, it is preferable to reduce the voltage of the leading electrode as compared with the trailing electrode. (V1 /
When the value of (A1) / (V2 / A2) is larger than 0.97, the voltage of the preceding electrode is too high and the molten pool (hot water pool)
Becomes unstable. On the other hand, if it is less than 0.78, the amount of spatter generated by the trailing electrode increases. Therefore, (V
The value of 1 / A1) / (V2 / A2) is 0.78 to 0.97.
And More preferably, it is 0.85-0.93.

In the case of Ar + CO ₂ , the shielding gas has an Ar mixing ratio of 55 to 96%, and Ar + He +.
In the case of (O ₂ or CO ₂ ), the mixing ratio of Ar + He is 5
5 to 96% ”In order to reduce the droplet size and the amount of spatter generated, the shield gas composition should be an inert gas (A
r, He) Rich is good. For Ar + CO ₂ When the mixing ratio of Ar exceeds 96%, also, Ar + He + (O
₂ or CO ₂ ) the mixing ratio of Ar + He is 96%
If it exceeds, the air will be easily entrained and blow holes will be generated in the weld bead. On the other hand, if the mixing ratio is less than 55%, the effect of atomizing droplets and reducing spatter cannot be exhibited in both cases. Therefore, when Ar + CO ₂ is used as the shield gas, the mixing ratio of Ar is 55 to 96.
%, And in the case of Ar + He + (O ₂ or CO ₂ ), Ar
The mixing ratio of + He was set to 55 to 96%.

Next, the solid wire for welding used as the leading electrode and the trailing electrode in the tandem arc welding method of the present invention will be described. The solid wire for welding used in the method of the present invention has a wire structure in which copper is not plated on the surface of the wire. Explaining this point, in the MAG welding (MAG welding) rich in inert gas, the surface tension of the droplets separated from the tip of the wire and transferred in the solid wire with copper plating is smaller than that without copper plating. , The droplets are not spherical but have an ellipsoidal shape that is elongated and elongated in the transition direction (falling direction). Therefore, the droplets that are transitioning from the wire tip to the molten pool of the base material are connected and the wire tip and the molten pool are A momentary short circuit phenomenon may occur in which a short circuit occurs for a very short time, and the connected droplets are broken and scattered to cause spatter generation.

Therefore, the solid wire for welding used in the method of the present invention has a structure in which the surface of the wire is not copper-plated and the wire component values are optimized so that the surface tension of the droplets in the inert gas-rich mag welding is improved. Is adjusted to a substantially spherical shape instead of an elongated shape, and a predetermined amount of a K compound (potassium compound) is applied to the surface of the wire to reduce the size of the droplet to form a droplet. The transition to the base material is made to be regular and smooth, and the occurrence of the above-mentioned instantaneous short-circuit phenomenon that causes the generation of spatter can be significantly suppressed.

The chemical components of the welding solid wire used in the method of the present invention and the reasons for limiting the values will be described below.

"No Copper Plating" The wire structure without copper plating makes it possible for oxygen to infiltrate the surface of the droplet quickly, and to reduce the amount of spatter by reducing the droplet size.

"C: 0.01 to 0.13% by weight" C
Is an effect that secures the strength of the welded portion, keeps the surface tension of the droplets moderate in the solid wire for welding without copper plating, and reduces the spatter caused by the instantaneous short circuit phenomenon in the inert gas-rich mag welding. It is an element that has.
However, when the amount of C is less than 0.01% by weight, the surface tension of the droplets is small and the effect of reducing spatter is not exhibited.
If it exceeds 3% by weight, the surface tension of the droplets becomes too large,
The droplets at the tip of the wire are repelled by the arc force and are scattered as large spatters, which in turn increases the spatter generation amount.
Therefore, the amount of C is set to 0.01 to 0.13% by weight, and 0.01 to 0.06% by weight from the viewpoint of lowering the sputtering.
Is more preferable.

"Si: 0.5 to 1.1% by weight" Si
Has the effect of acting as a deoxidizing element, keeping the surface tension of droplets moderate in the solid wire for welding without copper plating, and reducing spatter caused by the instantaneous short circuit phenomenon in inert gas-rich mag welding. It is an element.
However, when the amount of Si is less than 0.5% by weight, the surface tension of the droplets is small and the effect of reducing spatter is not exhibited.
If the content is more than wt%, the surface tension of the droplets becomes too large, and the droplets at the tip of the wire are repelled by the arc force and scattered as large spatters, which in turn increases the spatter generation amount. Therefore, the Si amount is set to 0.5 to 1.1% by weight, and the range of 0.6 to 0.9% by weight is more preferable from the viewpoint of lowering the sputtering.

"Mn: 0.5 to 2.2% by weight" Mn
Has the effect of acting as a deoxidizing element, keeping the surface tension of droplets moderate in the solid wire for welding without copper plating, and reducing spatter caused by the instantaneous short circuit phenomenon in inert gas-rich mag welding. It is an element.
However, when the amount of Mn is less than 0.5% by weight, the surface tension of the droplets is small and the effect of reducing spatter is not exhibited.
If the content is more than wt%, the surface tension of the droplets becomes too large, and the droplets at the tip of the wire are repelled by the arc force and are scattered as large spatters, which in turn increases the spatter generation amount. Therefore, the amount of Mn is 0.5 to 2.2% by weight, and the range of 1.4 to 1.9% by weight is more preferable from the viewpoint of lowering the sputtering.

"Ti: 0.04 to 0.35% by weight" T
i is an element that acts as a strong deoxidizing element, keeps the surface tension of the droplets moderate in the solid wire for welding without copper plating, and reduces spatter caused by an instantaneous short circuit phenomenon in mag welding. If the Ti content is less than 0.04% by weight, the surface tension of the droplets is small and the effect of reducing spatter is not exhibited, while if it exceeds 0.35% by weight, the surface tension of the droplets becomes too large and the droplets at the tip of the wire Is repelled by the arc force and scattered as large-sized spatters, which in turn increases the amount of spatters generated. Therefore, the Ti amount is 0.04 to 0.35% by weight, and 0.12 to 0.12% from the viewpoint of lowering the sputtering.
The range of 0.28% by weight is more preferable.

"S: 0.001-0.030% by weight"
S is an element that greatly affects the surface tension of the droplet. If the amount of S exceeds 0.030% by weight, the surface tension of the droplets is small and the effect of reducing spatter is not exhibited. If the amount of S is less than 0.001% by weight, the surface tension of the droplets becomes too large and the droplets at the wire tip arc. It is repelled by force and scatters as a large amount of spatter, which in turn increases the amount of spatter generated. Therefore,
The amount of S is 0.001 to 0.030% by weight, and the range of 0.005 to 0.025% by weight is more preferable from the viewpoint of lowering the sputtering.

"O: 0.001 to 0.020% by weight"
O is an element that has a great influence on the surface tension of the droplet, like S. If the amount of O exceeds 0.020% by weight, the surface tension of the droplets is small and the effect of reducing spatter is not exhibited.
If it is less than 0.001% by weight, the surface tension of the droplets becomes too large, and the droplets at the tip of the wire are repelled by the arc force and scattered as large spatters.
Therefore, the amount of O is 0.001 to 0.020% by weight, and 0.003 to 0.0
The range of 20% by weight is more preferable.

"1 to 15 ppm of K compound on the wire surface
(Kalium equivalent value) Must be applied. ”K compounds such as potassium stearate applied to the wire surface are
Since the ionization voltage is low to facilitate the emission of electrons, the potential gradient of the arc is lowered, the creeping of the arc to the droplet is promoted, and the arc is generated so as to wrap around the droplet at the tip of the wire. As a result, the detachment / migration of the droplets is promoted, the droplets are reduced in size and smoothly migrated, and the occurrence of the above-mentioned instantaneous short-circuit phenomenon that causes spattering can be reduced. If the amount of this K compound is less than 1 ppm, the creep of the arc to the droplet at the tip of the wire is not sufficient, and the effect of reducing the droplets that migrate to the base material and reducing spatter cannot be obtained. On the other hand, when it exceeds 15 ppm, rotation (a phenomenon in which the tip of the wire extends for a long time and droplets move while rotating at high speed) easily occurs at a high current, and the molten pool becomes unstable. Therefore, the amount of the K compound applied to the surface of the wire is set to 1 to 15 ppm (value converted to potassium).

"10 kg of wire containing MoS _{2 on the} wire surface
In the welding solid wire used in the method of the present invention, an appropriate amount of Mo is applied to the wire surface as a wire feed lubricant (lubricant particles).
By applying S ₂ , the friction force (feed resistance) when passing through the conduit tube (spring liner) for wire feeding can be reduced to improve the wire feeding property and stabilize the molten pool. The generation of spatter due to instability of the arc due to unstable feeding of the wire can be extremely reduced. The coating amount of MoS ₂ is 0.
If it is less than 01 g, the effect of improving the wire feeding property is not exhibited. On the other hand, when the amount is more than 0.50 g, the clogging amount in the conduit liner increases and conversely, wire feeding instability easily occurs, and the amount of spatter generation increases due to instability of the arc due to this feeding instability. . Therefore,
The amount of MoS ₂ applied on the wire surface is 10 k
It was set to 0.01 to 0.50 g per g.

The K compound and MoS ₂ on the wire surface
As for the coating, after the wire drawing is completed, there is a method of contact coating using a buff or the like, or a method of electrostatically non-contact coating. In this case, the K compound and MoS ₂ may be applied individually, or may be mixed and applied. There is also a method of applying a solution obtained by dissolving or dispersing these compounds in oil for wire feeding after completion of wire drawing. Furthermore, these are added to the wire drawing lubricant used in the intermediate die or the final die of the wire drawing process,
There is a method of attaching and applying to the wire surface during wire drawing treatment,
A coating method suitable for the wire manufacturing process may be appropriately selected.

FIG. 1 is a structural explanatory view showing an example of a welding robot apparatus used for carrying out the tandem arc welding method according to the present invention. This welding robot apparatus includes a multi-joint (6-axis) teaching reproduction welding robot 2 having a two-electrode integrated welding torch 1 attached to the wrist and a two-electrode integrated welding torch 1.
Wire feeding device 5 for feeding the leading electrode 3 to the leading electrode
And a welding power source 7 for the preceding electrode that supplies power to the preceding electrode 3.
A trailing electrode wire feeder 6 for feeding the trailing electrode 4 to the two-electrode integrated welding torch 1, a trailing electrode welding power source 8 for feeding power to the trailing electrode 4, and a welding robot 2 The robot control device 9 controls the operation of the robot and the output of the welding power sources 7 and 8, and the teaching box 10.

[0034]

EXAMPLES Tandem arc welding was carried out by using the welding robot apparatus according to the method of the present invention and the method of the comparative example, and the welding results were evaluated.

Structures shown in Tables 3 and 4 without copper plating
And solid wire for welding with wire diameter of 1.2 mmφ
(Table 3: Wire used in the method of the present invention, Table 4: Comparative example method)
Wire used in. Apply on the wire surface
Potassium stearate was used as the K compound.
Using these solid welding wires, the results are shown in Table 1 and Table 2.
Depending on the welding conditions, the SM490 steel plate with a plate thickness of 12 mm
Tandem arc welding was performed on the down fillet joint.
It was Shield gas composition is 80% Ar + 20% CO ₂ And
And the welding speed is 60 cm / min.

As shown in Tables 3 and 4, the evaluation of the welding results was carried out on the quality of the weld bead shape, which is strongly influenced by the stability of the molten pool, and the amount of spatter generated. These evaluations are ◎: very good, ◯: excellent,
□: Normal, Δ: Slightly inferior.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

In Tables 1 to 4, No. 1-No. 1
No. 1 is an example, and No. 1 is an example. 12-No. 32 is a comparative example.
No. which satisfies the constituent requirements of the present invention. 1-No. In all of the eleventh examples, the amount of spatter generated was small, the stability of the molten pool was good, and a weld bead with a good bead shape could be obtained.

On the other hand, in No. 12-No. The 32 comparative examples lacked any of the requirements specified in the present invention, and thus had the following problems. That is, No. In Comparative Example No. 12, the electrode-to-electrode distance D was too short, the arc and molten pool became unstable, the weld bead shape was poor, and a large amount of spatter occurred. No. In Comparative Example No. 13, the protruding length L of the leading electrode and the trailing electrode was too short and the tip temperature rose due to radiant heat from the molten pool, and the welding wire was fused to the high temperature tip when the arc was stopped. . N
o. In Comparative Example 14 on the contrary, the protruding length L was too long and the bead shape was good, but the gas shielding property was poor and blowholes were generated in the weld bead. No. In the comparative example of No. 15, the sum of the welding current density of the leading electrode and the welding current density of the trailing electrode was too large, and the molten pool became unstable,
The weld bead shape was bad. No. In the comparative example of No. 16, the electrode angle θ was too small, the molten pool became unstable, the weld bead shape was bad, and No. On the contrary, in the comparative example of No. 17, the electrode angle θ was too large, the molten pool became unstable, and the weld bead shape was bad. No. 18 comparative examples are (V1
The value of / A1) / (V2 / A2) was too small, and a lot of spatter occurred on the trailing electrode. No. The 19 comparative examples are
The value of (V1 / A1) / (V2 / A2) was too large, the voltage of the leading electrode was too high, the molten pool became unstable, and the weld bead shape was bad.

No. In Comparative Example No. 20, the amount of C in the welding wire was too large, so that the surface tension of the droplet became too large and spatter was generated frequently. No. In the comparative example of No. 21, since the amount of Si of the welding wire is too small, the surface tension of the droplet is small and spatter is often generated. Two
In the comparative example of 2, since the amount of Si in the welding wire is too large,
The surface tension of the droplets became too large and spatter was generated frequently. No. In the comparative example of No. 23, since the Mn amount of the welding wire is too small, the surface tension of the droplet is small and the spatter is often generated. In Comparative Example No. 24, the Mn content of the welding wire was too large, and therefore the surface tension of the droplet became too large and spatter was generated frequently. No. In Comparative Example No. 25, the amount of S in the welding wire was too large, and thus the surface tension of the droplet was small and spatter was generated frequently. No. In the comparative example of No. 26, since the amount of Ti in the welding wire is too small, the surface tension of the droplet is small and spatter is often generated.
o. On the contrary, in Comparative Example No. 27, the amount of Ti in the welding wire was too large, so that the surface tension of the droplet became too large and spatter was generated frequently. No. In Comparative Example No. 28, the O content of the welding wire was too large, and therefore the surface tension of the droplet was small and spatter was often generated. No. In Comparative Example 29, since the amount of K applied to the wire surface of the welding wire was too small, the effect of reducing spatter was not exhibited, and spatter was generated frequently. On the other hand, No. In the comparative example of No. 30, since the K content was too large, rotation occurred, the molten pool became unstable, and the weld bead shape was poor. No. 31
In the comparative example, since the amount of MoS ₂ applied to the wire surface of the welding wire was too small, the effect of improving the wire feedability was not exhibited, and spatter was often generated. On the other hand, No.
In Comparative Example No. 32, the amount of MoS ₂ was too large, so the amount of clogging in the conduit liner was large, and spatter was often generated due to arc instability due to unstable wire feeding.

[0044]

As described above, according to the tandem arc welding method of the present invention, the leading electrode and the trailing electrode made of a solid wire for welding are arranged at a predetermined distance in the welding direction, and the gas composition is When using a shield gas rich in inert gas to form one molten pool with two arcs and performing tandem arc welding, a weld bead with a small amount of spatter, good stability of the molten pool, and good bead shape Obtainable.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an example of a welding robot apparatus used for carrying out a tandem arc welding method according to the present invention.

FIG. 2 shows an electrode protrusion length L (wire protrusion length), an electrode angle θ, and a tandem arc welding method according to the present invention.
It is a figure for demonstrating the distance D between electrodes.

[Explanation of symbols]

1 ... 2 electrode integrated welding torch 1a ... torch body for leading electrode 1b ... torch body for trailing electrode 1c ... jacket 1d ... shield gas nozzle 2 ... teaching regenerative welding robot 3 ... leading electrode 4 ... trailing electrode 5 ... leading electrode Wire feeding device 6 ... Wire feeding device for trailing electrode 7 ... Welding power source for leading electrode 8 ... Welding power source for trailing electrode 9 ... Robot controller
10 ... Teaching box

Claims (6)

[Claims] 1. A front electrode and a rear electrode made of a solid wire for welding are arranged at a predetermined distance in the welding direction, and a shield gas having an inert gas rich gas composition is used. When forming a pool and performing tandem arc welding, the sum of the welding current density of the leading electrode and the welding current density of the trailing electrode: 500 to 1000 A /
mm ² , the electrode protruding length of each electrode: 22 to 35 mm, the distance between the electrodes: 10 to 29 mm, the electrode angle formed by the both electrodes when viewed from the direction orthogonal to the welding direction: 1 to 9 ° Tandem arc welding method. 2. The welding current of the leading electrode is A1, the welding voltage is V1, the welding current of the trailing electrode is A2, and the welding voltage is V2.
Then, the value of (V1 / A1) / (V2 / A2) is 0.
It is 78-0.97, The tandem arc welding method of Claim 1 characterized by the above-mentioned. 3. The shielding gas has a mixing ratio of Ar of 55 to 96% in the case of Ar + CO ₂ , and Ar + He +.
In the case of (O ₂ or CO ₂ ), the mixing ratio of Ar + He is 5
The tandem arc welding method according to claim 1, wherein the tandem arc welding is 5 to 96%. 4. A solid wire for welding, C: 0.
01-0.13% by weight, Si: 0.5-1.1% by weight,
Mn: 0.5 to 2.2% by weight, Ti: 0.04 to 0.3
5% by weight, S: 0.001 to 0.030% by weight, O:
0.001 to 0.020% by weight, respectively, the balance consists of Fe and unavoidable impurities, and the wire compound is coated with a K compound in an amount of 1 to 15 ppm (calcium conversion value). The tandem arc welding method according to any one of claims 1 to 3, wherein a solid wire for welding without copper plating, which is not plated, is used. 5. A solid wire for welding, C: 0.
01-0.06% by weight, Si: 0.6-0.9% by weight,
Mn: 1.4 to 1.9% by weight, Ti: 0.12 to 0.2
8% by weight, S: 0.005-0.025% by weight, O:
0.003 to 0.020% by weight, respectively, the balance consists of Fe and unavoidable impurities, and the wire surface is coated with 1 to 15 ppm (value converted to potassium) of a K compound, and the wire surface is copper. The tandem arc welding method according to any one of claims 1 to 3, wherein a solid wire for welding without copper plating, which is not plated, is used. 6. A solid wire for welding, wherein MoS ₂ is present on the wire surface in an amount of 0.01 to 0.5 per 10 kg of wire.
The tandem arc welding method according to claim 4 or 5, wherein 0 g is applied.