JP2001198689A - Method of laser welding for aluminum material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method pf a laser welding for an aluminum material, in which a filler metal is prevented from being stuck to a weld bead when a wire-shaped filler metal is fed a, so that workability of welding is improved. SOLUTION: A stitch state welded zone 13 is fumed on the surface of a welded material 11, the tip of a filler metal wire 12 is located at a position a little apart from the tip of the welded zone, and the position is irradiated with a laser beam LB. Then the irradiation with the laser beam LB is stopped after ts second from the termination of the feeding of the filler metal wire 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for laser welding aluminum or an aluminum alloy material (hereinafter collectively referred to as an aluminum material) by a YAG laser or the like, and more particularly to an aluminum material having an improved method for adding a filler material. Laser welding method.

[0002]

2. Description of the Related Art From the viewpoint of weight reduction, the use of aluminum materials for automobile parts or structural materials has been actively promoted, and therefore, there has been a demand for improvement in joining techniques of aluminum materials. 2. Description of the Related Art Conventionally, spot welding is frequently used for structural members made of steel in an automobile assembly process. But,
Aluminum has higher thermal conductivity and electrical conductivity than steel, so when resistance spot welding is performed on aluminum, the life of the electrode is shortened and the welding power source needs to be increased in capacity. There are various problems, such as the need to press the welded part of the material with a high pressure, and resistance spot welding cannot be easily performed under the same conditions as in the case of steel. In order to apply resistance spot welding to aluminum materials, it was necessary to at least increase the capacity of the welding power source and increase the size of the welding robot.

On the other hand, since a YAG laser can be welded with low heat input, application of the YAG laser to welding of aluminum materials has been started. This YAG laser can divide laser light in terms of output and time, so that it is possible to irradiate multiple points simultaneously or with a time difference, and to perform laser spot welding using conventional equipment and technology. be able to. In this case, unlike the resistance spot welding, the spot welding by the YAG laser is non-contact, so that the electrode life is not shortened. In addition, there is no need to replace the robot and newly install a large current power supply, and there is an advantage that laser spot welding can be performed using existing equipment.

[0004]

However, a filler material is sometimes added to add a component to a welded portion or to embed a crater formed in a molten and solidified portion by welding.
In this case, particularly in the case of spot welding an aluminum material, conventionally, the supply of the filler material wire has been stopped simultaneously with the stop of the laser beam irradiation. However, since the irradiation time of the laser beam is, for example, 1 second or less, and the filler wire is fed at a speed of, for example, 5 cm / sec, even if the laser irradiation is terminated and the feeding of the filler wire is stopped. In some cases, the filler metal wire enters the bead and adheres to the solidified bead.

[0005] In the case of welding in a stitch shape, a spot-shaped molten bead is formed by laser irradiation.
The irradiation position of the laser beam is slightly shifted, and the laser beam is again irradiated in a spot-like manner to form a molten bead on the next bead (which has already solidified). This operation is repeated to form a stitch. Weld the beads continuously. Also in the case of welding in this stitch shape, the operation of irradiating and stopping the laser beam is sequentially performed, and further, the irradiation position is moved stepwise. In each case, the supply of the filler wire is stopped, and further moved slightly. Need to be done.
Therefore, also in this case, the filler metal wire may enter the molten bead and adhere to the solidified bead.

As described above, when the filler wire is used, if the filler wire adheres to the bead, it is necessary to interrupt the welding operation each time, and the working efficiency is significantly reduced. There is a point. In particular, in applications that require high-speed welding, such a problem becomes a serious problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when a linear filler material is fed, it is possible to prevent the filler material from adhering to a welding bead. It is an object of the present invention to provide a method for laser welding an aluminum material capable of improving the weldability.

[0008]

According to the laser welding method for an aluminum material according to the present invention, a pair of materials to be welded made of aluminum or an aluminum alloy are overlapped at the welded portion, and a laser beam is applied to the material to be welded from the surface side. In the laser welding method for irradiating and welding an aluminum material, a linear filler material is fed to an irradiation position of the laser beam, and the feeding of the filler material is performed at a timing before a laser irradiation stop timing. It is characterized by stopping.

In the laser welding method for aluminum material, the laser welding is, for example, spot welding or stitch welding for welding the material to be welded in a spot-like or stitch-like manner.

In the present invention, since the supply of the filler material is stopped immediately before the stop of the laser beam irradiation, the filler material is prevented from entering the bead. The timing for stopping the supply of the filler material is before the timing for stopping the irradiation of the laser beam.When the supply of the filler material is stopped, the laser beam is being irradiated. The tip of the material melts and burns off, resulting in the tip of the filler material leaving the molten bead. Thereafter, the laser beam stops, so that it is possible to reliably prevent the filler material from entering the bead, and to smoothly proceed to the next bead formation.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a view showing a first embodiment of the present invention. FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a front sectional view. In this embodiment, the present invention is applied to laser spot welding. The upper plate 1 and the lower plate 2 to be welded are overlapped at the end to be spot-welded, and this end is sandwiched between a cylindrical lower holding member 4 and three rod-shaped upper holding members 3 to be pinched. I do. The upper holding member 3 removes a spot to be spot-welded and presses a position surrounding the spot downward. On the other hand, the lower holding member 4 presses the position immediately below the spot to be spot-welded upward.

The position of the lower surface of the lower plate 2 that matches the spot to be spot-welded is recessed so as to form a recess 5. Therefore, the lower plate 2 and the lower holding member 4 do not come into contact with each other in the concave portion 5 to form a space. The upper plate 1 and the lower plate 2 are plate members made of aluminum or an aluminum alloy, and have a thickness of, for example, 1 mm or more.

The upper plate 1 and the lower plate 2 are overlapped with each other at a welded portion, and the upper holding member 3 and the lower holding member 4 sandwich the welded portion. The laser beam LB is irradiated in a pulsed manner with a predetermined energy at the same time as the feed wire 10 is fed. This laser is, for example, a YAG laser or a CO ₂ laser.

Then, the upper plate 1 and the lower plate 2 are melted into spots by the heat energy generated by the irradiation of the laser beam, and a penetration penetration portion 6 is formed. Then, the filler metal wire 1 is supplied to the penetration portion 6 and melted to replenish the material of the bead portion, thereby preventing the formation of a crater.

Next, at a point of time ts seconds or more immediately before the laser beam irradiation stop timing, the supply of the filler wire is stopped. For this reason, the tip of the filler metal wire is heated and melted by the laser beam that is still being irradiated, and is kept in a state where there is a sufficient space between the tip of the filler wire and the molten bead. Then, the irradiation of the laser beam is stopped. Therefore, the filler wire does not enter the molten bead, and the tip of the filler wire does not adhere to the solidified bead. The ts seconds may be set appropriately experimentally so that the filler wire does not adhere to the bead after welding.

In this embodiment, as shown in FIG. 1 (b), since the concave portion 5 is formed on the lower surface of the lower plate 2, the penetrating penetration portion 6 is easily formed. When the penetration penetration portion 6 is formed, air bubbles hardly remain in the welded portion, and a welded portion having no blowhole defect can be easily obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the present invention is applied to stitch-like welding. First, as shown in FIG. 2A, a stitch-shaped welded portion 13 welded in a conventional process is formed on the surface of the material to be welded 11, and a welding progress direction is formed from the tip of the welded portion 13. The tip of the filler wire 12 is positioned at a position slightly apart from the laser beam LB, and the laser beam LB is irradiated to this position, and the filler wire 12 is fed at a speed of, for example, 5 cm / sec.

Then, as shown in FIG. 2B, while the irradiation of the laser beam LB continues, the filler wire 1
Stop feeding 2. As a result, the distal end portion of the filler wire 12 melts at a portion sufficiently receiving heat near the laser beam LB to form a molten bead, but a portion slightly separated from the laser beam LB is separated from the molten bead. It remains as it is. Therefore, the tip of the filler material wire 12 is separated from the molten bead and stopped.

Next, as shown in FIG. 2C, after stopping the filler wire 12, the irradiation of the laser beam LB is stopped. Thereby, the molten bead is solidified, and a stitch-like weld bead 13 having a surface shape partially overlapping the conventional bead is formed. In the present invention, since the irradiation of the laser beam LB is stopped after the filler wire 12 is stopped, it is possible to prevent the filler wire 12 from adhering to the solidified bead.

In this way, even in the case of welding in a stitch shape, it is possible to prevent the filler material wire from adhering to the solidified bead in the same manner as in the first embodiment.

[0021]

As described above, according to the present invention,
Since the timing at which the linear filler material is fed is at least ts seconds before the stop of the laser beam irradiation, when the laser beam stops, the filler material stops at a position separated from the molten bead. This prevents the filler material from adhering to the bead after the bead solidifies.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of the present invention, wherein (a) is a perspective view and (b) is a front sectional view.

FIGS. 2A to 2C are schematic diagrams showing a second embodiment of the present invention.

[Explanation of symbols]

 1: upper plate 2: lower plate 3: upper holding member 4: lower holding member 5: concave portion 6: penetration penetration portion 10, 12: filler metal wire 11: material to be welded 13: welded portion

Claims (2)

[Claims] 1. A laser welding method for an aluminum material, wherein a pair of materials to be welded made of aluminum or an aluminum alloy is overlapped at a welding portion thereof, and the material to be welded is irradiated with a laser beam from a surface side to perform welding. A method for laser welding an aluminum material, comprising: feeding a linear filler material to the irradiation position of (1), and stopping the supply of the filler material at a timing before a laser irradiation stop timing. 2. The laser welding method according to claim 1, wherein the laser welding is spot welding or stitch welding in which the material to be welded is spot-shaped or stitch-welded.