JPH0215313B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high-speed tack welding method in which tack welding is performed continuously at high speed prior to main welding.

[Conventional technology]

Conventionally, when tack welding is performed at high speed, welding is performed by a two-electrode MIG welding method using a leading electrode 1 and a trailing electrode 2, as shown in FIG. That is, the distance between the leading electrode 1 and the trailing electrode 2, each using a solid wire as a welding wire, is shortened to prevent the molten metal 4 generated by the arc 3 of the leading electrode 1 from flowing out behind the trailing electrode 2. Welding is performed by forming a continuous weld bead while blocking it with the arc 5 of the trailing electrode 2.

[Problem that the invention seeks to solve]

In this two-electrode welding method, the leading electrode 1 ensures the penetration depth of the base metal, and the trailing electrode 2 secures the penetration depth of the molten metal.
The purpose of use of both electrodes is different.

However, conventionally, the leading electrode 1 and the trailing electrode 2
In both cases, a solid wire is used as the welding wire, and as shown in FIG. 4, in this solid wire 6, a droplet 7 is transferred in a flow, the tip of the wire is elongated, and an arc 8 is constricted. Therefore, it is suitable for ensuring the penetration depth of the base metal of the leading electrode 1, but it is suitable for satisfying the purpose of blocking the molten metal 4 of the trailing electrode 2 when performing tack welding at a very high speed. As a result, the flow of the molten metal becomes unstable, resulting in an irregular weld bead (humping bead) with a significantly uneven weld bead shape.

If an irregular bead occurs during tack welding, welding defects such as slag entrainment and poor fusion are likely to occur during actual welding, and there is also the problem that it is difficult to follow the weld line during actual welding. Therefore, it was necessary to suppress the welding speed of tack welding to about 6 m/min.

[Means to solve the problem]

The high-speed tack welding method of the present invention uses a solid wire as the welding wire of the leading electrode and a flux-cored wire as the welding wire of the trailing electrode to form a continuous weld bead at high speed.

[Effect]

In order to create a continuous weld bead during high-speed tack welding using multiple electrodes, it is necessary to stabilize the pool of molten metal that forms between the leading and trailing electrodes. In order to stably create this puddle of molten metal, use a solid wire as the welding wire of the leading electrode to ensure the base metal penetration depth. It is necessary to block the metal. When a flux-cored wire is used as the welding wire for the trailing electrode, the width of the arc column is wider than when a solid wire is used, so the molten metal can be effectively blocked by the arc force.

〔Example〕

FIG. 1 shows an arc configuration diagram when tack welding is performed by an embodiment of the present invention using two electrodes,
In the figure, 1 is a leading electrode using a solid wire, 2 is a trailing electrode using a flux-cored wire, 3 is the arc of the leading electrode 1, 5 is the arc of the trailing electrode 2, and 4 is molten metal.

The continuity of the bead is achieved by reducing the thermal gradient and suppressing the plasma airflow behind the leading electrode 1, thereby reducing the temperature difference between the base material and the molten metal, resulting in a continuous bead. When a flux-cored wire is used as the welding wire for the trailing electrode 2, the droplets 10 of the flux-cored wire 9 migrate as a lump due to the influence of the flux filled inside the wire, as shown in FIG. , the width of the arc 5 becomes wider. In other words, the plasma airflow is not constricted and the energy is dispersed. The arc 5 with the width of the trailing electrode 2 widened suppresses the plasma airflow behind the leading electrode 1, reducing the thermal gradient and creating a stable pool of molten metal 4.

Therefore, even if the tack welding speed is increased, the bead formation is stable, and a smooth weld bead can be continuously obtained even at high speeds.

According to the above example, using a steel plate with a thickness of 12 mm, we physically tack welded a Y groove with a groove angle of 90 degrees and a depth of 4 mm, and determined the limit of welding speed that does not cause irregular beads. As a result, the welding speed limit is approximately 10m/
minute, which is a significant improvement compared to 6 m/min when tack welding is performed with two electrodes in the conventional example. Note that in the above tack welding, the welding current of the leading electrode 1 is 1500A, and the welding current of the trailing electrode 2 is 400A.

〔Effect of the invention〕

As explained above, in a tack welding method using a plurality of electrodes, this invention uses a solid wire as the welding wire of the leading electrode, a flux-cored wire as the welding wire of the trailing electrode, and each electrode By effectively exerting this effect, a pool of molten metal can be stably formed between the electrodes, and a continuous and smooth weld bead can be formed at high speed. Further, by forming a continuous weld bead, it becomes easy to follow the weld line during main welding, and it is also possible to prevent weld defects from occurring during main welding.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an arc according to an embodiment of the present invention.
FIG. 2 is a diagram of the arc configuration of a flux-cored wire, FIG. 3 is a diagram of the arc configuration of a conventional example, and FIG. 4 is a diagram of the arc configuration of a solid wire. 1... Leading electrode, 2... Trailing electrode, 3, 5, 8
... arc, 4 ... molten metal, 6 ... solid wire, 7, 10 ... droplet, 9 ... flux cored wire.

Claims (1)

[Claims] 1 In a welding method that uses multiple electrodes to perform tack welding of base metals at high speed, tack welding is performed using a solid wire as the welding wire of the leading electrode and a flux-cored wire as the welding wire of the trailing electrode. A high-speed tack welding method characterized by welding.