JP2005329430A - Laser arc complex welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser arc complex welding method capable of simply and efficiently welding aluminum or aluminum alloy. <P>SOLUTION: A laser head 3 to irradiate a work 1 to be welded with laser beams 2 is arranged so that the axis of the laser beams 2 is orthogonal to a surface of the work 1, shield gas 4 is ejected toward the work 1, and an arc torch 6 to generate arc by conducting a welding wire 5 is arranged behind the laser head 3 in the welding direction. Welding is performed while the arc torch 6 is inclined to have an angle of advance with respect to the welding direction, and the arc targeting position 8 on the surface of the work 1 is before the laser beam irradiation point 7 in the welding method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser / arc composite welding method in which laser welding and arc welding are combined, and more particularly to a laser / arc composite welding method suitable for welding aluminum or an aluminum alloy material.

  Laser / arc combined welding, which combines laser welding and arc welding, uses two heat sources with different energy densities, so it stabilizes the arc, speeds up the welding speed, relaxes the groove dimensional accuracy, Effects such as improved penetration depth, improved joint strength, and suppression of welding defects can be obtained (see Non-Patent Document 1). In recent years, aluminum alloys have been adopted as automobile structural materials for reasons such as weight saving and promotion of recycling, and laser-arc combined welding methods have been applied as methods for joining aluminum alloys in automobile manufacturing processes ( Non-patent document 2).

  FIG. 5 is a perspective view showing a conventional laser-arc combined welding method. In the conventional laser / arc combined welding method, generally, as shown in FIG. 5, a laser head 103 for irradiating a workpiece 101 with a laser beam 102 in front of the welding direction and an arc torch 104 in the rear are arranged. Before the weld metal 103 is formed on the welded portion 101 of the workpiece 101 by arc welding, the laser beam 102 is irradiated to the root gap 106 of the groove 105 and the root face surface is melted by laser, and then arc welding is performed. Thus, the droplets of the welding wire are caused to flow into the groove.

  Conventionally, a YAG laser induced arc filler wire composite welding method in which the irradiation positions of the laser beam and the arc are the same has also been proposed (see Patent Document 1). Further, a laser / arc combined welding apparatus in which a laser head and an arc torch are coaxially arranged has been developed (see Non-Patent Document 3). In the coaxial laser / arc combined welding apparatus described in Non-Patent Document 3, the penetration depth is increased by irradiating a laser beam to a position 2 mm ahead or 2 mm behind the arc irradiation point.

JP 2003-290948 A Nobuyuki Abe, 1 other, “Laser / Arc Composite Welding Method and its Future”, Welding Technology, July 2003, p. 62-67 Noritaka Eguchi, “Application of Laser-Arc Hybrid Welding to Aluminum Alloy”, Welding Technology, July 2003, p. 79-83 Takashi Ishide, 3 others, “Hybridization of arc and YAG laser”, Journal of the Japan Welding Society, 2001, Vol. 70, No. 4, p. 12-17

  However, the conventional techniques described above have the following problems. That is, in the conventional laser-arc combined welding method shown in FIG. 5, the distance from the arc pole at the tip of the welding wire to be an electrode to the plasma on the keyhole formed by laser irradiation is increased, and the potential gradient is increased. As a result, the convergence (energy density) of the electron transfer amount decreases, resulting in a problem that the penetration depth becomes shallow. Further, the welding method described in Patent Document 1 has a problem that the laser head to be used is large and can be applied only to a member having a flat surface in order to avoid physical interference between the laser head and a member to be welded. .

  The laser-arc combined welding apparatus described in Non-Patent Document 3 has a problem that the head becomes large and the mechanism becomes complicated. Further, in this laser / arc combined welding apparatus, it is necessary to divide the laser beam before focusing, and to match the laser beam split at the focusing point accurately. There is a problem that the energy of light is lost and the efficiency is lowered. Furthermore, a dedicated condensing lens for condensing the laser beam has to be provided, and there is a problem that the apparatus price is expensive. Furthermore, if the laser head and the arc torch are arranged coaxially, a shielding gas is blown from directly above the welded portion, so that a sufficient gas atmosphere cannot be formed in the traveling direction, and the welding speed is limited. Is done.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a laser-arc combined welding method capable of easily and efficiently welding aluminum or an aluminum alloy material.

  The laser-arc composite welding method according to the present invention is a laser-arc composite welding method in which a workpiece is composite-welded with laser light and an arc, wherein an arc torch is disposed behind the laser head in the welding direction, and the arc torch The welding is characterized in that welding is carried out so that the welding target surface has an advancing angle, and further the arc aiming position on the surface of the material to be welded is in front of the laser beam irradiation point in the welding direction.

  In the present invention, when the tip of the welding wire is extended to the surface of the material to be welded, the arc aiming position, which is the point where the tip of the welding wire and the surface of the material to be welded contact, is ahead of the laser beam irradiation point in the welding direction. Since welding is performed in this manner, the arc length, which is the distance between the anode and cathode of the arc, is shortened, and energy efficiency can be increased. In addition, since the arc torch is arranged to be inclined rearward in the welding direction so as to have a forward angle with respect to the welding direction, the arc torch is supplied from the arc torch without blowing shield gas from the front in the welding direction toward the weld. With this shielding gas, a sufficient shielding gas atmosphere can be formed in front of the weld pool in the welding direction. Furthermore, since the existing laser apparatus and the existing arc welding apparatus can be used, laser / arc combined welding can be easily performed without preparing a special apparatus.

  The protruding length of the wire during welding may be controlled so that the tip of the welding wire supplied from the arc torch is behind the laser beam irradiated from the laser head. Thereby, the penetration depth of a welding part can be increased. This laser-arc combined welding method can be used for welding aluminum or aluminum alloy materials.

  According to the present invention, welding is performed such that the arc target position is ahead of the laser beam irradiation point in the welding direction, so that the arc length can be shortened and energy efficiency can be improved, and the existing laser apparatus and arc welding can be performed. Since the apparatus can be used, laser-arc combined welding can be easily performed.

  Hereinafter, a laser / arc combined welding method according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1A is a cross-sectional view showing the laser-arc combined welding method of the present embodiment, and FIG. 1B is an enlarged cross-sectional view showing the welded portion of FIG. The laser / arc combined welding method of the present embodiment is a method of welding by combining laser welding and arc welding as shown in FIG. 1A, and a laser head that irradiates a workpiece 1 with laser light 2. 3 and an arc torch for injecting a shield gas 4 toward the workpiece 1 and energizing a welding wire 5 sent from a wire feeding device (not shown) to generate an arc. 6 is used.

  In the laser / arc combined welding method of the present embodiment, the laser head 3 is arranged so that the central axis of the laser beam 2 is perpendicular to the surface of the workpiece 1, and the arc torch 6 is positioned more than the laser head 3. Arrange behind the welding direction. At this time, the arc torch 6 is inclined at a forward angle toward the rear side in the welding direction so that an angle θ formed by the surface of the workpiece 1 and the central axis of the arc torch 6 is, for example, 60 to 75 °.

  In the laser / arc combined welding method with a high welding speed, an atmosphere of shielding gas 4 must be formed in front of the welded pool 11 in the welding direction. Therefore, in the conventional laser / arc combined welding method, the shielding gas is blown toward the welded portion from the front in the welding direction rather than the laser head. On the other hand, in the laser / arc combined welding method of the present embodiment, the arc torch 6 is disposed to be inclined rearward in the welding direction, so that the welding direction of the molten pool 11 is caused by the shield gas 4 supplied from the arc torch 6. A sufficient shielding gas 4 atmosphere can also be formed in the front. In addition, when welding aluminum alloy by the laser-arc combined welding method of this embodiment, as the shielding gas 4, for example, an inert gas such as argon can be used.

  Further, in the laser / arc combined welding method of the present embodiment, as shown in FIG. 1 (b), the arc aiming position 8 is set in front of the laser beam irradiation point 7 in the welding direction. In the laser / arc combined welding, arc pole points (cathode points or anodes) on the surface of the material to be welded 1 are generated by plasma 12 generated in the keyhole formed in the molten pool 11 melted by the laser beam 2 and in the vicinity of the opening. Since the point) moves to the laser weld, the heat sources synergize to obtain heat with high energy density. For this reason, the position where the droplet 5b dropped from the tip of the welding wire 5 adheres on the surface of the workpiece 1, that is, the line segment perpendicular to the surface of the workpiece 1 passing through the welding wire tip 5 a during welding. The energy efficiency can be improved by shortening the distance between the intersection 9 (hereinafter referred to as the droplet adhesion point 9) between the surface of the workpiece 1 and the workpiece 1 and the arc target position 8. Therefore, in the laser-arc combined welding method of the present embodiment, the tip of the welding wire 5 before the start of welding (before the occurrence of the arc) is positioned more than the position (laser beam irradiation point) 7 where the laser beam 2 is irradiated during welding. It arrange | positions so that it may become the welding direction front, and it starts welding so that the arc aiming position 8 may become the welding direction front rather than the laser irradiation point 7. FIG. During the welding, the arc aiming position 8 is set in front of the laser irradiation point 7 in the welding direction. Thereby, the arc length is shortened and an efficient heat source can be obtained.

  However, if the arc target position 8 is set to be considerably forward of the laser beam irradiation point 7, the welding wire tip 5a at the time of welding is arranged in front of the laser beam irradiation point 7 in the welding direction, and the laser beam 2 is to be welded. Before reaching 1, the welding wire 5 and the filler metal are consumed as energy for melting, and as a result, the weld may be shallowly penetrated. For this reason, in the laser-arc combined welding method of the present embodiment, the arc aiming position 8 is set in front of the laser irradiation point 7 in the welding direction, and the welding wire tip 5a during welding is more than the laser beam 2. It is preferable to be behind the welding direction. The distance d between the laser beam irradiation point 7 and the arc aiming position 8 is more preferably less than 3 mm. Thereby, sufficient penetration is obtained.

  As described above, in the laser / arc combined welding method of this embodiment, the laser head 3 and the arc torch 6 need to be arranged coaxially as in the laser / arc combined welding apparatus described in Non-Patent Document 3 described above. In addition, since it is not necessary to prepare special optical parts, laser-arc combined welding can be easily and inexpensively performed by combining an existing laser apparatus and an existing arc welding apparatus. Further, unlike the laser / arc combined welding apparatus described in Non-Patent Document 3 described above, the energy of the laser beam is not lost, so that welding can be performed with high efficiency.

  Hereinafter, the effect of the Example of this invention is demonstrated compared with the comparative example which remove | deviates from the scope of the present invention. FIG. 2 is a perspective view showing a welding method according to an embodiment of the present invention, FIG. 3A is a sectional view showing the welded portion, and FIG. 3B is a plan view. First, as an example of the present invention, JIS standard 5182 aluminum alloy plates 21a and 21b having a plate thickness of 4 mm are overlapped by composite welding using both YAG laser 22 laser welding and MIG welding, and the end surfaces thereof are overlapped. Along the overlap surface, the edge angle welding of the MIG torch 23 and the distance D between the arc aiming position 8 and the laser irradiation point 7 were changed and the edge joint was welded. The welding conditions at that time were such that the laser output was 4.0 kW, the focal length was 200 mm, and the focal positions were the surfaces of the aluminum alloy plates 21a and 21b. Further, a MIG welding current was 140 A, a voltage was 21 V, and a welding wire having a diameter of 1.2 mm defined by JIS standard A-5356-WY was used. Further, argon was used as the shielding gas, the shielding gas flow rate was 25 l / min, the welding speed was 2.0 m / min, and the welding length was 200 mm.

  Next, the throat thickness t of the weld metal 24 was measured for each joint welded under the above conditions. FIG. 4 is a graph showing the relationship between the distance D and the throat thickness t of the joint, with the distance D between the laser beam irradiation point and the arc target position on the horizontal axis and the throat thickness t on the vertical axis. In FIG. 4, the case where the arc target position 8 is ahead of the laser beam irradiation point 7 in the welding direction is negative, and the case where the arc target position 8 is behind the laser beam irradiation point 7 in the welding direction is positive. As shown in FIG. 4, in any case where the inclination angle θ of the MIG torch 23 is 60 °, 70 °, and 78 °, the laser beam irradiation point 7 is ahead of the arc aiming position 8 in the welding direction. That is, in the joint of the embodiment in which the distance D between the laser beam irradiation point 7 and the arc target position 8 is smaller than 0, the arc target position 8 is behind the laser beam irradiation point 7 in the welding direction, that is, the laser beam irradiation point 7. And the joint D of the comparative example in which the distance D between the arc target position 8 is larger than 0, the throat thickness t is thicker and the penetration depth is deeper.

(A) is sectional drawing which shows the laser arc combined welding method concerning embodiment of this invention, (b) is an expanded sectional view which shows a welding part. It is a perspective view which shows the welding method of the Example of this invention. (A) is sectional drawing which shows the welding part in the Example of this invention, (b) is the top view. It is a graph showing the relationship between the distance D and the throat thickness, with the distance D between the laser beam irradiation point and the arc target position on the horizontal axis and the throat thickness on the vertical axis. It is a perspective view which shows the conventional laser arc combined welding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101; To-be-welded material 2,102; Laser beam 3,103; Laser head 4; Shielding gas 5; Welding wire 5a; Welding wire front-end | tip 5b; Droplet 6,104; Arc torch 7; Arc target position 9; droplet adhesion part 11; molten pool 12; plasma 21a, 21b; aluminum alloy plate 22; YAG laser 23; MIG torch 24; weld metal 105; groove 106; root gap d, D; Distance between point 7 and arc target position 8; Throat thickness

Claims (3)

In a laser-arc combined welding method in which workpieces are combined and welded with laser light and an arc, the arc torch is disposed behind the laser head in the welding direction, and the arc torch has an advancing angle with respect to the welding direction. The laser-arc combined welding method, wherein the welding is performed such that the welding is performed such that the arc target position on the surface of the workpiece to be welded is in front of the laser beam irradiation point in the welding direction. The wire protrusion length at the time of welding is controlled so that the tip of the welding wire supplied from the arc torch is behind the laser beam irradiated from the laser head in the welding direction. The laser-arc combined welding method described. 3. The laser-arc combined welding method according to claim 1, wherein the method is used for welding aluminum or an aluminum alloy material.

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