JP2008055506A - Two-welding wire feeding arc welding method, multilayer welding method, and narrow groove welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an improved bead shape in which no humping, undercut and underfill are generated when welding is performed for a steel material with a low molten metal viscosity. <P>SOLUTION: In a two-welding wire feeding arc welding method, a first (preceding) welding wire 11 and a second (succeeding) welding wire 12 insulated from each other are supplied from the nozzle 6 at the tip end of a welding torch to weld a steel material with a low molten metal viscosity. In this method, a welding current Iw is energized in the preceding welding wire to generate an arc 3 to form a molten pool 21 while no welding current is energized in the succeeding welding wire. The succeeding welding wire is inserted in a position rising after the molten pool 21 is dug down by the pressure of the arc 3, in the two welding wire feeding arc welding method. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in welding performance of a two-weld wire feeding arc welding method in which two welding wires are fed close to each other for welding.

  2. Description of the Related Art Conventionally, various two-weld wire feed arc welding methods for feeding and welding two welding wires from one or more welding torches have been proposed. The two welding wire feeding arc welding method can perform high welding welding and high-speed welding as compared with a general consumable electrode arc welding method using a single welding wire. Hereinafter, the prior art regarding this 2 welding wire feeding arc welding method is demonstrated.

[Prior art 1]
Prior art 1 described in Patent Document 1 is a consumable electrode arc welding method in which an angle formed by a preceding welding wire and a succeeding welding wire is inserted into a nozzle under a maximum of 20 degrees, and an arc is generated by the preceding welding wire. The welding wire is inserted into the molten pool, a part of the welding current flowing from the preceding welding wire to the base metal is shunted, led to the following welding wire, and joined to the ground end of the welding power source. That is, a welding current is supplied to the preceding welding wire to generate an arc to form a molten pool, and a part of this welding current is diverted to the subsequent welding wire to be supplied and inserted into the molten pool. A welding method is disclosed.

[Prior Art 2]
In the prior art 2 described in Patent Document 2, a consumable electrode wire is disposed in parallel as a preceding welding wire and a filler wire as a subsequent welding wire in the welding progress direction, and the filler wire is inserted into the molten pool to be melted. And welding power is controlled by controlling the ground current flowing between the ground ends of the welding power source and changing the amount of current led to the filler wire via the molten pool. That is, a welding current is applied to the preceding welding wire to generate an arc to form a molten pool, and a current for controlling the current to generate heat in the subsequent welding wire is controlled and inserted into the molten pool. A method is disclosed.

[Prior Art 3]
In the prior art 3 described in Patent Document 3, a first welding wire (preceding welding wire) and a second welding wire (following welding wire) that are electrically insulated from one welding torch are preset. The first welding wire is repeatedly energized with a first peak current and a first base current energized as one cycle, and the first welding wire is repeatedly applied to the second welding wire. Repeats energization with a second peak current energization and a second base current energization as one cycle, and two arcs are formed between the first welding wire, the second welding wire and the base material. Welding is generated. Furthermore, in the prior art 3, the energization of the first base current and the second base current is controlled so as to suppress the instability of the arc state due to the interference between the two arcs.

JP-A-3-275280 Republished patent WO02 / 018086 JP 2001-287031 A

  In lap fillet welding of high-strength steel for automobiles, a flat bead shape as shown in FIG. 8A is required from the viewpoint of ensuring fatigue strength. At the same time, as shown in FIG. 8B, a welded portion without undercut and underfill in the upper plate portion is required. As the above-mentioned high-tensile steel for automobiles, a steel material (hereinafter referred to as a low-viscosity steel material) having a low molten metal viscosity is often used. When this low-viscosity steel material is welded, the viscosity of the molten pool is low, so the molten wire does not fill the bottom of the molten pool deeply dug by the strong arc force caused by the large current flow. It often causes weld defects such as fill.

  When the above-described two welding wire feeding arc welding methods of the prior arts 1 and 2 are applied to the welding of the low-viscosity steel material described above, the molten wire filling to the bottom of the molten pool is performed as a subsequent welding wire (filler wire). Promoted by the insertion of. For this reason, humping is less likely to occur, so the welding speed range (high-speed weldability) in which good welding is possible is expanded. However, in the prior arts 1 and 2, since the succeeding welding wire is heated and inserted into the molten pool, the molten pool becomes a high temperature state and the surface tension becomes weak, so the occurrence of undercut and underfill is not improved. . Furthermore, there is a case where the arc state becomes unstable due to interference caused by the current flowing through the succeeding welding wire to the arc of the preceding welding wire.

  Moreover, when the 2 welding wire feeding arc welding method of the prior art 3 described above is applied to welding of a low-viscosity steel material, filling of the molten wire to the bottom of the molten pool is promoted by insertion of the subsequent welding wire. . For this reason, humping is less likely to occur, so that high-speed weldability is improved. However, in the prior art 3, since the molten pool becomes a high temperature state by heat input from two arcs and the surface tension becomes weak, the occurrence of undercut and underfill is not improved. Furthermore, because of the restriction due to interference between the two arcs, the distance between the two welding wires may not be set to a desired distance that maximizes the high-speed weldability.

  Therefore, the present invention provides a two-weld wire feed arc welding method capable of suppressing the occurrence of humping, undercutting, and underfill in welding of low-viscosity steel materials.

In order to solve the above-described problems, a first invention is a two-weld wire feeding arc welding method in which a first welding wire and a second welding wire that are insulated from each other are closely fed and welded.
The first welding wire is a preceding welding wire and the second welding wire is a trailing welding wire;
The preceding welding wire is energized with a welding current to generate an arc to form a molten pool,
The second welding wire feeding arc is characterized in that the subsequent welding wire is inserted at a position that promotes cooling of the molten pool without passing a welding current, and cools the molten pool and compensates the molten metal. It is a welding method.

  Moreover, 2nd invention is a position where the position which accelerates | stimulates cooling of the said molten pool is a position which rises after the said molten pool is dug down by the pressure from the said arc of the said prior welding wire, It is characterized by the above-mentioned. It is the 2 welding wire feeding arc welding method of 1st invention description.

Further, a third invention is a multilayer pile welding method using the two-welding wire feed arc welding method according to the first or second invention,
Each layer is welded by reciprocating the first welding wire and the second welding wire;
At the time of welding in the forward direction, the first welding wire is the preceding welding wire and the second welding wire is the following welding wire,
In the multi-pass welding method, the second welding wire is used as the preceding welding wire and the first welding wire is used as the subsequent welding wire during welding in the backward direction.

  Moreover, 4th invention is a narrow groove welding method which welds the narrow groove of a thick plate using the 2 welding wire feeding arc welding method of 1st or 2nd invention description.

  According to the present invention, in welding of low-viscosity steel material, by inserting a subsequent welding wire at a position that promotes cooling of the molten pool, it is possible to fill the molten metal and form a good surplus. The occurrence of humping can be suppressed. Furthermore, according to the present invention, the temperature of the molten pool can be lowered by inserting it into the rising portion of the molten pool without cooling the subsequent welding wire, so that the surface of the molten pool can be reduced. It is possible to suppress the occurrence of undercut and underfill by increasing the tension. Furthermore, in the present invention, no current is passed through the subsequent welding wire, so that interference of the preceding welding wire with the arc does not occur.

  According to the third aspect of the present invention, in the multi-layer welding method using a material that reduces the viscosity of the molten metal, it is possible to form a sound weld bead by suppressing the occurrence of undercut and underfill, Enables weld welding. Furthermore, since the reciprocal welding can be efficiently performed only by reversing the welding direction, the welding operation time can be shortened.

  According to the fourth invention, the occurrence of undercut and underfill can be suppressed by using the two-weld wire feed arc welding method for narrow groove welding using a material with low viscosity of the molten metal. it can. Furthermore, solidification cracks in the welded portion can be suppressed. Furthermore, since two welding wires are used, high welding welding is possible, and the welding time is shortened.

[Embodiment 1]
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of a two-welding wire feed arc welding apparatus according to Embodiment 1 of the present invention. The figure shows a case where the first welding wire 11 is a preceding welding wire and the second welding wire 12 is a subsequent welding wire. Hereinafter, a description will be given with reference to FIG.

  The welding power source PS outputs a welding voltage Vw between the power feed tip 4 and the base material 2 to generate an arc 3 in the first welding wire 11 (preceding welding wire), and outputs a welding current Iw. A first feed control signal Fc1 for controlling the rotation of the motor M1 and a second feed control signal Fc2 for controlling the rotation of the second feed motor M2 are output.

  The first feed motor M <b> 1 rotates the first feed roll 71, pressurizes it with the first pressure roll 81, and feeds the first welding wire 11. The first feeder WF1 includes the first feeding motor M1, the first feeding roll 71, the first pressure roll 81, and the like. The first welding wire 11 is supplied with power from the power supply tip 4 in the welding torch and generates an arc 3 between the base metal 2 and forms a molten pool 21. As a welding method for generating the arc 3, CO2 welding, MAG welding, pulse MAG welding, or the like is used.

  The second feed motor M2 rotates and drives the second feed roll 72, pressurizes the second feed roll 72, and feeds the second welding wire 12 (following welding wire). The second feeder WF2 includes the second feeding motor M2, the second feeding roll 72, the second pressure roll 82, and the like. The second welding wire 12 is fed in the guide member 5 in the welding torch while being insulated from the preceding welding wire 11, and is inserted at a position that promotes cooling of the molten pool 21. The second welding wire 12 is inserted in the cooled state without conducting current.

  As shown in the figure, the first welding wire 11 is disposed in advance with respect to the welding direction, and the second welding wire 12 is disposed downstream, and both the welding wires 11 and 12 are fed through the nozzle 6. Be paid. As described above, the welding wires 11 and 12 are electrically insulated from each other. In the figure, both welding wires 11 and 12 are examples of feeding in one welding torch. However, two welding torches may be brought close to each other and fed in each welding torch.

  FIG. 2 is a schematic diagram of an arc generating portion in the present invention. The figure shows a case where the first welding wire 11 is a preceding welding wire and the second welding wire 12 is a subsequent welding wire. Between the preceding welding wire and the base material 2, an arc 3 through which a welding current I flows is generated, and a molten pool 21 is formed. The molten pool 21 below the arc 3 is dug down by receiving pressure (arc force) from the arc 3. The bottom layer dug down is the bottom. The molten pool 21 gradually rises and rises because the influence of the arc force weakens as it moves away from here. And the back is solidified to form a surplus. Since it is during welding of a low-viscosity steel material, if the viscosity of the molten metal is low, the digging will become deeper. When the digging is deep, it reaches the non-melting part at the bottom and causes a humping phenomenon.

  In order to prevent the occurrence of humping, a subsequent welding wire is inserted into the molten pool 21 dug down by an arc force. The subsequent welding wire is inserted in the cooled state (cold wire state) without passing current. When the succeeding welding wire is inserted, the succeeding welding wire becomes a molten metal and is supplemented, so that a healthy surplus is formed without lack of swell. As a result, the occurrence of humping can be prevented.

  Furthermore, since the subsequent welding wire is inserted into the molten pool 21 in the cooled state, the temperature of the molten pool 21 is lowered and the surface tension is increased. As a result, even if the viscosity of the molten pool 21 is low, the surface tension is increased, so that the occurrence of undercut and underfill can be suppressed and a sound bead shape can be obtained. Since the cooling effect differs depending on the position in the molten pool 21 where the subsequent welding wire 12 is inserted, the subsequent welding wire 12 is inserted at a position where cooling of the molten pool is promoted, as will be described later.

  As the insertion position of the succeeding welding wire is closer to the arc 3 than the portion where the succeeding welding wire is raised, the tip of the succeeding welding wire 12 is more likely to touch the arc 3 and drops into the molten pool 21 as a droplet. . At this time, large spatters are scattered and the bead appearance is deteriorated. Furthermore, since the droplets drop into the molten pool 21 at a high temperature, the cooling effect of the molten pool 21 described above is gradually reduced, and the effect of suppressing the occurrence of undercut and underfill is also reduced. Therefore, if the tip of the subsequent welding wire does not become a droplet by the arc 3 before the portion where the insertion position rises, cooling of the molten pool is promoted.

  As the insertion position of the succeeding welding wire 12 is behind the rising portion, the succeeding welding wire is inserted after the surplus is substantially formed with the molten metal in the rising portion being insufficient. . For this reason, the humping suppression effect becomes low. Furthermore, since it is far from the arc 3, the temperature of the molten pool 21 is lowered, and the subsequent welding wire is not sufficiently melted, thereby causing poor fusion. Therefore, it is particularly important that the insertion position of the subsequent welding wire is appropriate.

  As described above, the position where the subsequent welding wire is inserted into the molten pool 21 is in a slightly wider range before and after the portion where the molten pool swells. If inserted in this range, cooling of the molten pool is promoted. . When a higher cooling effect is required, it may be inserted into the rising part of the molten pool.

  FIG. 3 is a diagram illustrating an example of an appropriate insertion position of the above-described subsequent welding wire. This figure shows a case where a lap fillet joint made of a low-viscosity steel material is welded at 1.5 m / min. The arc is generated by a pulse MAG welding method. The horizontal axis of the figure indicates the weld pool length in the weld pool (longitudinal diameter of the weld pool), and the vertical axis indicates the distance (inter-wire distance) between the preceding welding wire and the subsequent welding wire. The minimum value of the major axis of the weld pool is about 4 mm from the stability of the arc state.

  As shown in the figure, the range in which a good bead is formed is a range in which the distance between wires is approximately 3 to 7 mm. However, when the major axis of the molten pool is 7 mm or less, the appropriate upper limit value of the distance between wires is substantially equal to the major axis of the molten pool. When the distance between the wires becomes less than the appropriate lower limit, the insertion position of the subsequent welding wire becomes closer to the arc than the portion where the molten pool swells, and as described above, the cooling effect of the molten pool decreases and undercut and Underfill is likely to occur. If the distance between wires exceeds the appropriate upper limit value, the insertion position of the subsequent welding wire will be behind the part where the weld pool swells, and as described above, the formation of surplus will be poor and humping will occur. It becomes easy to do.

  According to the first embodiment described above, in welding of a low-viscosity steel material, by inserting a subsequent welding wire at a position that promotes cooling of the molten pool, the molten metal is filled to form a good surplus. Therefore, the occurrence of humping can be suppressed. Furthermore, according to the first embodiment, the temperature of the molten pool can be lowered by inserting the trailing welding wire into the rising portion of the molten pool without being heated, so that the molten pool can be lowered. It is possible to suppress the occurrence of undercut and underfill by increasing the surface tension. Furthermore, in the present invention, no current is passed through the subsequent welding wire, so that interference of the preceding welding wire with the arc does not occur.

  In the above description, the low-viscosity steel material is used as a base material, but the viscosity of the molten pool may be low even when the low-viscosity steel material is not used as the base material. When a pulse MAG welding wire is used as the preceding welding wire, the pulse MAG welding wire is made of a low-viscosity material for the purpose of facilitating droplet transfer by the pulse. For this reason, when this welding wire becomes molten metal, a molten pool having low viscosity is formed. Even in this case, the present invention is effective. In the following description, the low-viscosity steel material and the welding wire as described above are collectively described as materials that lower the viscosity of the molten metal.

[Embodiment 2]
FIG. 4 is a diagram showing a multilayer pile welding method using the above-described two welding wire feed arc welding method according to the second embodiment of the present invention. The first welding wire 11 and the second welding wire 12 are fed from one welding torch 6, and the welding torch 6 is reciprocated to weld each layer. FIG. 3A shows the time when welding is performed by moving the welding torch 6 in the forward direction, and FIG. 4B shows the time when welding is performed by moving the welding torch 6 in the backward direction. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 5A, during the forward direction welding, the first welding wire 11 is a preceding welding wire and the second welding wire 12 is a subsequent welding wire. Therefore, an arc 3 is generated between the first welding wire 11 that is the preceding welding wire and the base material 2, and consumable electrode arc welding is performed, and the second welding wire 12 that is the subsequent welding wire is energized. Without being inserted into the molten pool. In this way, the above-described 2-welding wire feed arc welding is performed.

  As shown in FIG. 5B, at the time of backward welding, the second welding wire 12 is a preceding welding wire, and the first welding wire 11 is a subsequent welding wire. Therefore, the arc 3 is generated between the second welding wire 12 that is the preceding welding wire and the base material 2 to perform consumable electrode arc welding, and the first welding wire 11 that is the subsequent welding wire is energized. Without being inserted into the molten pool. In this way, the above-described 2-welding wire feed arc welding is performed.

  FIG. 5 is a configuration diagram of a welding apparatus for carrying out a multi-layer welding method using a two-weld wire feed arc welding method. In the figure, the same components as those in FIG. 1 described above are denoted by the same reference numerals and description thereof is omitted. Hereinafter, different components will be described.

  The second welding power source PS2 outputs the welding voltage Vw and the welding current Iw from the positive output terminal P1 when the first welding wire 11 is a preceding welding wire, and is positive when the second welding wire 12 is a preceding welding wire. The welding voltage Vw and the welding current Iw are output from the output terminal P2. The second welding power source PS2 outputs a first feed control signal Fc1 for controlling the rotation of the first feed motor M1 and a second feed control signal Fc2 for controlling the rotation of the second feed motor M2.

  The welding voltage Vw output from P1 is applied between the first power feed tip 41 and the base material 2 to generate the arc 3. On the other hand, the welding voltage Vw output from P2 is applied between the second power feeding tip 42 and the base material 2 to generate an arc.

  In the above, one welding power source PS2 has two plus output terminals P1 and P2, but two welding power sources may be used so that each has P1 and P2.

  According to the above-described second embodiment, in the multi-layer welding method using a material that lowers the viscosity of the molten metal, it is possible to suppress the occurrence of undercut and underfill and form a sound weld bead, Enables high welding welding. Furthermore, since the reciprocal welding can be efficiently performed only by reversing the welding direction, the welding operation time can be shortened.

[Embodiment 3]
Since construction machines, steel frames, bridges, and the like are thick plate welded structures, a large amount of weld metal is required at the welded portion, and a long time is required for welding. For this reason, welding is recently performed with a narrow groove weld joint having a narrow groove width and a large groove depth. In such narrow gap welding, when a material that lowers the viscosity of the molten metal is used for the base material or the welding wire as described above, undercut and underfill are likely to occur.

  FIG. 6 is a cross-sectional view of a narrow groove weld. As shown in the figure, in a weld formed by a narrow groove weld joint, crystal grains called columnar crystals meet at the center of the weld metal. And since the bead width with respect to the penetration depth is narrow, the molten metal cannot be filled in the central part where the crystal grains meet due to welding heat shrinkage, and a shrinkage-like solidification crack often occurs.

  FIG. 7 is a diagram showing a bead formation process when a narrow groove welded joint is welded using the above-described two-weld wire feed arc welding method. This figure corresponds to FIG. 6 described above. The figure shows the case where a material that makes the molten metal less viscous is used.

  The growth direction of the columnar crystals is the direction of heat flow by welding. In the present embodiment, as shown in FIG. 5A, the heat flow is directed not only to the plate width direction but also to the upper plate thickness where the subsequent welding wire is fed to cool the molten pool. For this reason, in this embodiment, as shown in FIG. 5B, the columnar crystals are less likely to receive strain concentration without meeting at the center of the welded portion, so that welding heat shrinkage occurs. However, solidification cracking is unlikely to occur.

  According to the above-described third embodiment, the occurrence of undercut and underfill is suppressed by using the two-weld wire feed arc welding method for narrow groove welding using a material with low viscosity of the molten metal. can do. Furthermore, solidification cracks in the welded portion can be suppressed. Furthermore, since two welding wires are used, high welding welding is possible, and the welding time is shortened.

It is a block diagram of the 2 welding wire feed arc welding apparatus which concerns on Embodiment 1 of this invention. It is a schematic diagram of the arc generation part in 2 welding wire feeding arc welding which concerns on Embodiment 1 of this invention. In the 2 welding wire feeding arc welding method which concerns on Embodiment 1 of this invention, it is a figure which shows an example of the insertion position of the subsequent welding wire from which a favorable bead is obtained. It is a figure which shows the multilayer pile welding method which concerns on Embodiment 2 of this invention. It is a block diagram of the welding apparatus for enforcing the multilayer pile welding method which concerns on Embodiment 2 of this invention. It is sectional drawing of the welding part which shows the subject in the narrow gap welding method which concerns on Embodiment 3 of this invention. It is a figure which shows the bead formation process in the narrow gap welding method which concerns on Embodiment 3 of this invention. It is a figure which shows the favorable bead cross section for explaining the subject of a prior art, and a bad bead cross section.

Explanation of symbols

2 Base material 3 Arc 4 Feeding tip 5 Guide member 6 Nozzle 9 Welding bead 11 First welding wire 12 Second welding wire 21 Weld pool 41 First feeding tip 42 Second feeding tip 71 First feeding roll 72 Second feeding Roll 81 First pressure roll 82 Second pressure roll Fc1 First feed control signal Fc2 Second feed control signal Iw Welding current M1 First feed motor M2 Second feed motor PS Welding power supply P1 First plus output Terminal P2 Second plus output terminal Vw Welding voltage WF1 First feeder WF2 Second feeder

Claims (4)

In a two-weld wire feed arc welding method in which a first welding wire and a second welding wire that are insulated from each other are fed in close proximity and welded,
The first welding wire is a preceding welding wire and the second welding wire is a trailing welding wire;
The preceding welding wire is energized with a welding current to generate an arc to form a molten pool,
The second welding wire feeding arc is characterized in that the subsequent welding wire is inserted at a position that promotes cooling of the molten pool without passing a welding current, and cools the molten pool and compensates the molten metal. Welding method.   2. The welding wire according to claim 1, wherein the position that promotes cooling of the weld pool is a position that rises after the weld pool is dug down by pressure from the arc of the preceding welding wire. Feed arc welding method. In the multilayer pile welding method using the 2 welding wire feeding arc welding method according to claim 1 or 2,
Each layer is welded by reciprocating the first welding wire and the second welding wire;
At the time of welding in the forward direction, the first welding wire is the preceding welding wire and the second welding wire is the following welding wire,
A multilayer prime welding method, wherein during welding in the backward direction, the second welding wire is used as the preceding welding wire, and the first welding wire is used as the subsequent welding wire. A narrow groove welding method for welding a narrow groove of a thick plate using the two-welding wire feed arc welding method according to claim 1.

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