JP2001205465A - Method of composite welding by laser arc and welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of a composite welding by a laser and arc where the laser and the arc are used jointly with which method an arc is stable even when the welding is carried out at high speed, a welding bead having an excellent form is available and the efficiency of the welding work is remarkably improved, and to provide a composite welding equipment using the laser and arc. SOLUTION: The front and the rear sides of an arc electrode 5 with respect to the advancing direction of a welding work are irradiated with a guide beam B1 and a following beam B2, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding technique for steel, aluminum alloy, and the like, and more particularly, to a technique for improving butt welding, lap welding, fillet welding, and the like by using a laser and an arc together. The present invention relates to a laser-arc combined welding method that can be performed efficiently and a welding apparatus for performing such laser-arc combined welding.

[0002]

2. Description of the Related Art As a welding method using an arc and a laser together, a method described in, for example, JP-A-6-238474 is known. According to this publication, a TIG welding torch for preheating is arranged in front of a laser torch, and by irradiating a laser to a portion preheated by a TIG arc, a thick material can be processed even with a low-output laser oscillator. Have been.

[0003]

However, according to an experiment conducted by the present inventor, when the arc electrode is disposed in front of the laser irradiation position, there is no problem when the welding speed is relatively low. When the welding speed is increased, the arc becomes unstable, and the weld bead tends to be disturbed, and it has been confirmed that there is a problem in the weldability at high speed. Laser
This has been a problem in the arc composite welding method.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional laser-arc combined welding method, and has a good shape without causing arc instability even in high-speed welding. It is an object of the present invention to provide a laser-arc combined welding method capable of obtaining a bead and greatly improving the efficiency of welding work, and a welding apparatus for performing such laser-arc combined welding.

[0005]

A laser-arc combined welding method according to a first aspect of the present invention is characterized in that a laser beam is applied to the front and rear of the arc electrode in the welding direction. Such a configuration in the laser-arc combined welding method is used as means for solving the above-mentioned conventional problems.

In the laser-arc combined welding method according to the second aspect of the present invention, the arc electrode is a TIG electrode. In the laser-arc combined welding method according to the third aspect, the arc electrode is a MIG electrode. It has a certain configuration.

A laser according to claim 4 of the present invention.
In the arc combined welding method, the focus of the leading beam disposed in front of the arc electrode is located within a range of less than 5 mm on the forward side in the welding progress direction with respect to the electrode center point where the axis center line of the arc electrode crosses the surface of the workpiece. The leading beam and the succeeding beam are irradiated so that the focal point of the succeeding beam disposed behind the arc electrode is located within a range of 3 to 10 mm on the rear side in the welding traveling direction with respect to the electrode center point, 5
In the laser-arc combined welding method according to the above, the subsequent beam is irradiated so that the height of the beam focal point is within 1.0 mm below the surface of the workpiece,
In the laser-arc combined welding method according to claim 6, the material to be welded is an aluminum alloy material. In the laser-arc combined welding method according to claim 7 of the present invention, the power density of the leading beam is reduced. 17kW /
mm ² or more, the power density of the subsequent beam 21.2KW /
mm ² or more.

According to another aspect of the present invention, there is provided a laser-arc combined welding apparatus comprising: an arc torch for holding an arc electrode; a first laser head for irradiating a leading beam forward of the arc torch in a welding direction; A second laser head for irradiating a subsequent beam to the rear side in the welding direction, and a gas nozzle for supplying an inert gas such as argon or helium coaxially with the arc electrode of the arc torch. The laser-arc combined welding apparatus according to No. 9 has an arc torch holding an arc electrode and an optical system for condensing a YAG laser transmitted through two optical fibers into two beam spots, respectively. A laser head that irradiates the beam in front of the arc electrode and the other beam behind the arc electrode, and the arc electrode of the arc torch A gas nozzle for supplying an inert gas such as argon or helium is provided coaxially. The laser-arc combined welding apparatus according to claim 10 of the present invention further comprises an arc torch holding an arc electrode and a single arc torch. It has an optical system that focuses a YAG laser transmitted via an optical fiber to two beam spots by a beam splitter, and irradiates one beam forward of the arc electrode and the other beam backward of the arc electrode. A laser head and a gas nozzle for supplying an inert gas such as argon or helium coaxially with an arc electrode of an arc torch are provided to solve such a conventional problem described above in a laser-arc combined welding apparatus. This is characterized in that it is a means for performing

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A laser-arc combined welding method according to the present invention irradiates a laser beam forward and backward of an arc electrode with respect to a welding traveling direction. The arc generated from the arc electrode is stabilized by the plasma induced by the irradiation of the leading beam located in front of the arc electrode,
Since the subsequent laser beam is efficiently absorbed by the molten pool formed by the leading beam and the arc, a deep penetration weld bead can be stably obtained even during high-speed welding.

[0010] At this time, the arc electrode may be a second electrode.
Further, as described in claim 3, both the TIG electrode and the MIG electrode can be used. That is, an arc may be generated between the non-consumable tungsten electrode and the workpiece, or an arc may be generated between the tip of the continuously supplied filler wire and the workpiece. Substantially the same effect can be obtained.

The irradiation positions of the leading beam and the trailing beam are set at the electrode center point (the point where the axis center line of the arc electrode intersects the surface of the material to be welded). Irradiation is performed so that the focus of the leading beam is located within a range of less than 5 mm on the front side in the welding direction, and the subsequent beam is positioned within a range of 3 to 10 mm on the rear side in the welding direction with respect to the electrode center point. Irradiation can be performed such that the focal point is located, so that the arc is more stable and a deeper penetration can be obtained even during high-speed welding. Furthermore, since a deeper penetration is obtained for the succeeding beam, the irradiation is performed such that the focal height position is within a range of 1.0 mm below the surface of the material to be welded as described in claim 5. It is desirable to do.

The laser-arc combined welding method according to the present invention can be applied to welding of all metallic materials.
The combined use of arc heat and the splitting of the laser beam into a leading beam and a trailing beam can increase the total energy density supplied to the welded portion. In particular, the effect is great when applied to an aluminum alloy having a high laser reflectance.

[0013] When the laser-arc combined welding method according to the present invention is applied to such an aluminum alloy, in order to obtain a sufficient penetration depth in high-speed welding, it is necessary to provide a method as described in claim 7. It is desirable that the power density of the leading beam be 17 kW / mm ² or more and the power density of the succeeding beam be 21.2 kW / mm ² or more.
That is, the power density of the leading laser is 17 kW / mm ²
If it is less than 30, the plasma generated by laser irradiation is not sufficiently formed, and the effect of arc stabilization at the time of high-speed welding tends not to be obtained.
When it is less than W / mm ² , sufficient penetration depth at high speed may not be obtained in lap welding of an aluminum alloy having a plate thickness of 1.0 to 3.0 mm, which is most frequently used.

An apparatus for performing such laser-arc combined welding is as described in claim 8.
A laser head for irradiating a leading beam and a laser head for irradiating a succeeding beam are respectively provided before and after an arc torch, or transmitted from two optical fibers as described in claim 9. The laser beams are bundled in parallel by a laser head, focused on two beam spots, and one beam is irradiated to the front of the arc electrode and the other beam is irradiated to the rear of the arc electrode. As described in claim 10, a laser beam transmitted from one optical fiber is focused on two beam spots by a beam splitter in a laser head unit, and one beam is directed forward of an arc electrode. One in which the other beam is irradiated to the rear of the arc electrode can be used.

[0015]

According to a first aspect of the present invention, there is provided a laser-arc combined welding method wherein the laser beam is applied to the front and back of the arc electrode in the welding direction. Therefore, the plasma generated by the irradiation of the leading beam preceding the arc electrode stabilizes the arc, and the subsequent laser beam is efficiently absorbed by the molten pool formed by the leading beam and the arc, so that high-speed welding is performed. This provides an extremely excellent effect that a deep penetration weld bead can be stably obtained even at times.

In the laser-arc combined welding method according to the second and third aspects of the present invention, a TIG electrode or a MIG electrode is used as the arc electrode, so that a stable arc can be obtained and defects can be obtained. In the laser-arc combined welding method according to the fourth aspect, the focal point of the leading beam is located within a range of less than 5 mm on the front side in the welding traveling direction with respect to the electrode center point. Since both beams are irradiated so that the focal point of the subsequent beam is also located within a range of 3 to 10 mm on the rear side in the welding traveling direction with respect to the electrode center point,
The arc can be further stabilized even at the time of high-speed welding, and the penetration of the welded portion can be further deepened. In the laser-arc combined welding method according to claim 5, the focal height of the subsequent beam is changed from the surface of the workpiece to the surface. Since the irradiation is performed so as to be within the range up to 1.0 mm below, further deeper penetration can be obtained.

A laser according to claim 6 of the present invention.
In the arc composite welding method, the welding method is applied to an aluminum alloy material, so that it can be used for welding aluminum alloy materials having a high reflectance of a laser beam more widely than a normal laser welding method. In the laser-arc combined welding method according to claim 7 of the present invention, when welding such an aluminum alloy material, the power density of the leading beam is set to 17 kW / mm ^2.
As described above, the power density of the succeeding beam is set to 21.2 kW / mm ²
Because welding is performed as described above, even in high-speed lap welding of the most frequently used aluminum alloy with a plate thickness, a sufficient arc stabilizing effect by plasma is obtained and a deep welded sound weld portion is reliably obtained. The effect is excellent.

On the other hand, a laser according to claim 8 of the present invention.
The arc combined welding apparatus includes an arc torch having an arc electrode, a gas nozzle for supplying an inert gas, a first laser head, and a second laser head. The subsequent beam is applied to the front and rear sides of the arc torch, respectively. The laser-arc combined welding apparatus according to claim 9 of the present invention also includes an arc torch, a gas nozzle, and a laser head, The laser head has an optical system for condensing the YAG laser transmitted through the two optical fibers into two beam spots, and irradiates the condensed beams to the front and rear sides of the arc electrode, respectively. The laser-arc combined welding apparatus according to claim 10 of the present invention also includes an arc torch, a gas nozzle, It has a laser head, and the laser head has an optical system that focuses a YAG laser transmitted through one optical fiber to two beam spots by a beam splitter, and forwards both the focused beams in front of an arc electrode. And the rear side, respectively, so that both have a structure suitable for carrying out the laser-arc combined welding method according to the present invention, and the present invention The laser-arc combined welding method can be easily performed.

[0019]

EXAMPLES The present invention will be described below more specifically based on examples.

FIG. 1 shows an embodiment of an apparatus for performing laser-arc combined welding according to the present invention. A laser-arc combined welding apparatus 1 shown in FIG. 1 is a MIG torch as an arc torch. 2, a first laser head 3a located on the front side of the MIG torch 2 and a second laser head 3b located on the rear side of the MIG torch 2 with respect to the welding progress direction indicated by the arrow in the figure. ing.

The MIG torch 2 has a conduit cable 4
Is connected to a MIG welding device (not shown) via
The filler wire 5 serving as a consumable electrode (arc electrode) is supplied, and the MIG torch 2 is provided with a gas nozzle 2a opened around the filler wire 5, and a shielding gas made of an inert gas such as argon is supplied to the filler wire W. They are supplied coaxially. On the other hand, the first and second
The laser heads 3a and 3b are connected to a YAG laser oscillator (not shown) via optical fibers 6a and 6b, and the laser heads are located before and after a point where the filler wire 5 intersects the workpiece W (hereinafter referred to as an electrode center point). Beams B1 (leading beam) and B2 (subsequent beam) are irradiated respectively.

Such a combined laser-arc welding apparatus 1
, The arc voltage by the MIG torch 2 is 22V,
The current is set to 180 A, the output of the leading laser beam B1 is 1.2 kW, and the output of the succeeding laser beam B2 is 2.
2A, the distance d1 between the center point of the electrode where the filler wire 5 intersects the workpiece W and the focal point of the leading beam B1 is 2 mm, and the distance d1 between the center point of the electrode and the subsequent beam B2 is shown in FIG. Assuming that the distance d2 from the focal point is 5 mm,
2 mm aluminum alloy materials W1 and W2 were overlapped and lap welding was performed from the upper side of the alloy material W1.

FIG. 3 shows the relationship between the tensile strength and the welding speed of the lap welded joint obtained in this way, as shown in FIGS. 2 (b) and (c), in the case of only the leading beam B1 and in the case of the subsequent beam. FIG. 6 is a diagram showing a comparison with the case of only a beam B2.
In the case of only the leading beam B1 or the succeeding beam B2, the output of these laser beams was set to 4 kW in accordance with the total laser output in the method of the present invention described above.

As a result, as shown in FIG. 2B, when only the leading beam B1 is irradiated without irradiating the succeeding beam B2, a sufficient penetration can be obtained when the welding speed exceeds 4 m / min. And the tensile strength began to decrease. When only the succeeding beam B2 is irradiated without irradiating the leading beam B1, the welding speed is 5 m / m.
in, the tensile strength is secured until it exceeds 5 m / m
When the value exceeds "in", a tendency to sharply decrease was observed. On the other hand, in the case of the welding method according to the present invention in which the leading beam B1 and the succeeding beam B2 were irradiated before and after the arc, it was confirmed that welding could be performed without decreasing the strength up to a welding speed of 7 m / min.

When the welding bead was observed with only the subsequent beam B2, the arc was not sufficiently formed when the welding speed was 6 m / min, resulting in an extremely unstable bead appearance. On the other hand, in the case of using only the leading beam B1, a weld bead having no problem up to the high-speed range was obtained, but sufficient welding strength was not obtained due to the shallow penetration depth. On the other hand, in the case of the welding method according to the present invention, a stable arc is obtained by the leading beam B1, and the molten pool formed by the leading beam B1 and the arc is irradiated with the succeeding beam B2 to efficiently absorb energy. Therefore, it is considered that welding at a high speed became possible.

FIG. 4 shows that the focal point of the succeeding beam B2 is fixed at the tip of the filler wire 5, that is, at a position 5 mm behind the electrode center point (d2 = 5 mm), the position of the leading beam B1 is changed, and the welding speed is 7 m. / Min shows the change in the penetration depth when welding is performed in the same manner. According to this, the focal position of the leading beam B1 is 5 m from the electrode center point.
When the distance exceeds m, the penetration depth was found to be shallow. This is presumably because, when the leading beam B1 was too far from the arc, the effect of stabilizing the arc during high-speed welding with plasma was reduced.

FIG. 5 shows that the focal position of the leading beam B1 is fixed 2 mm ahead (d1 = 2 mm) from the center of the electrode, the position of the trailing beam B2 is changed, and the welding speed is 7 m / m.
In the same manner, the depth of penetration changes when welding is performed, and according to this result, deep penetration is obtained when the focal position of the subsequent beam B2 is within a range of 3 to 10 mm from the electrode center point. Was confirmed.

FIG. 6 shows that the focus of the leading beam B1 is 2 mm ahead (d1 = 2 mm) from the center of the electrode and the focus of the succeeding beam B2 is 5 mm behind (d2 = 5) from the center of the electrode.
mm), and shows the change in penetration depth when the same welding is performed at a welding speed of 7 m / min by changing the focal height position of the succeeding beam B2 in the same manner. It has been found that deep penetration can be obtained when the focal height of the beam B2 is within a range of 1.0 mm from the surface of the workpiece W to the inside of the workpiece W.

In addition, regarding the output of the leading beam B1, when the output is lower than 1.2 kW at a beam diameter of 0.3 mm, that is, the power density is 17 kW / mm ^2.
If less than, a phenomenon that the arc tends to be unstable was observed. This is probably because if the power density of the leading beam B1 is too low, the reflection of the beam on the surface of the workpiece W becomes large. The output of the succeeding beam B2 can be welded even if it is low. However, for example, in order to weld a steel plate or an aluminum alloy having a thickness of about 0.6 to 3.0 mm generally used in an automobile or the like at a high speed. When the power density was less than 21.2 kW / mm ² , it was recognized that insufficient strength was likely to occur due to insufficient penetration.

FIG. 7 shows another embodiment of the apparatus for performing laser-arc combined welding according to the present invention. The laser-arc combined welding apparatus 11 shown in the figure is a MIG as an arc torch. Torch 2 and laser head 13
The laser head 13 includes an optical system including a collimation lens 13a and a focusing lens 13b therein. The laser head 13 is provided with a YAG laser oscillator (not shown) via two optical fibers 6a and 6b. The transmitted laser is focused on two beam spots, respectively, and a leading beam B1 and a following beam B
2 irradiates the front and rear sides of the filler wire 5 supplied from the MIG torch 2.

FIG. 8 shows still another embodiment of an apparatus for performing laser-arc combined welding according to the present invention, and shows a laser-arc combined welding apparatus 21 shown in FIG.
Is a laser-arc combined welding apparatus 1 according to the above embodiment.
1, MIG torch 2 as an arc torch,
The laser head 23 mainly includes a collimation lens 23a, a focusing lens 23b, and a beam splitter 23c.
The laser beam transmitted from the YAG laser oscillator (not shown) via the optical fiber 6 is split by the beam splitter 23c and condensed into two beam spots, and the leading beam B1 and the succeeding beam B2 And irradiates the front and rear sides of the filler wire 5 supplied from the MIG torch 2, respectively, and has the same functions as the laser-arc combined welding apparatuses 1 and 11 according to the above-described embodiments. .

In each of the above embodiments, the MIG electrode is used as the arc electrode.
It has been confirmed that basically the same function and effect can be obtained by the G electrode. At this time, if necessary, a filler material such as a filler wire can be supplied to the molten pool.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a laser-arc combined welding apparatus according to the present invention.

FIG. 2 (a) is a schematic explanatory view showing the arrangement of an arc electrode, a leading beam and a succeeding beam in the laser-arc combined welding apparatus shown in FIG. (B) It is the schematic explanatory drawing which shows arrangement | positioning of an arc electrode and a beam in the comparative example using only a leading beam. (C) It is a schematic explanatory drawing which shows the arrangement | positioning of an arc electrode and a beam in the comparative example using only the succeeding beam.

FIG. 3 is a graph showing the welding speed in the laser-arc combined welding according to the present invention in comparison with the case of the laser-arc combined welding according to the comparative example using only the leading beam or the succeeding beam.

FIG. 4 is a graph showing the relationship between the penetration depth and the focal position of the leading beam in the laser-arc combined welding according to the present invention.

FIG. 5 is a graph showing a relationship between a penetration depth and a focal position of a subsequent beam in laser-arc combined welding according to the present invention.

FIG. 6 is a graph showing a relationship between a penetration depth and a focal height position of a subsequent beam in laser-arc combined welding according to the present invention.

FIG. 7 (a) is an explanatory view showing another embodiment of the laser-arc combined welding apparatus according to the present invention. (B) FIG.
It is the arrow view from the upper part of the laser-arc combined welding apparatus shown to (a).

FIG. 8 is an explanatory view showing still another embodiment of the laser-arc combined welding apparatus according to the present invention.

[Explanation of symbols]

 1,11,21 Laser-arc combined welding equipment 2 MIG torch (arc torch) 2a Gas nozzle 3a First laser head 3b Second laser head 5 Filler wire (arc electrode) 6,6a, 6b Optical fiber 13,23 Laser head 13a, 23a Collimation lens (optical system) 13b, 23b Focusing lens (optical system) 23c Beam splitter (optical system) B1 Leading beam (laser beam) B2 Subsequent beam (laser beam) W, W1, W2

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B23K 9/26 B23K 9/26 D 26/04 26/04 C 26/06 26/06 C 26/08 26/08 K 26/14 26/14 Z // B23K 103: 10 103: 10 (72) Inventor Masayuki Inoue 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term in Nissan Motor Co., Ltd. 4E001 AA03 BB07 BB08 BB12 CB01 DD02 DD03 EA01 4E068 BC01 CA02 CA11 CD02 CD04 CE08 CH08 CJ01 DB04

Claims (10)

[Claims] 1. A laser-arc combined welding method comprising irradiating a laser beam forward and backward in a welding traveling direction with respect to an arc electrode. 2. The laser-arc combined welding method according to claim 1, wherein the arc electrode is a TIG electrode. 3. The laser-arc combined welding method according to claim 1, wherein the arc electrode is a MIG electrode. 4. A focal point of a leading beam disposed in front of the arc electrode is located within a range of less than 5 mm on a forward side in a welding traveling direction with respect to an electrode center point at which an axis center line of the arc electrode intersects a surface of a workpiece, The focal point of the subsequent beam disposed behind the arc electrode is 3-1 to the rear side in the welding traveling direction with respect to the electrode center point.
The laser-arc combined welding method according to any one of claims 1 to 3, wherein the leading beam and the succeeding beam are irradiated so as to be located within a range of 0 mm. 5. The laser-arc combined welding method according to claim 4, wherein the subsequent beam is irradiated such that the height of the beam focus is within 1.0 mm below the surface of the workpiece. . 6. The laser according to claim 4, wherein the material to be welded is an aluminum alloy material.
Arc combined welding method. 7. The power density of the leading beam is 17 kW / m.
m ² or more, power density of subsequent beam is 21.2 kW / m
The laser according to claim 6, characterized in that m ² or more - arc hybrid welding method. 8. An arc torch holding an arc electrode,
A first laser head for irradiating a leading beam on the forward side in the welding direction of the arc torch, a second laser head for irradiating a succeeding beam on the rear side in the welding direction of the arc torch, and argon, coaxial with the arc electrode of the arc torch; A laser-arc combined welding apparatus comprising a gas nozzle for supplying an inert gas such as helium. 9. An arc torch holding an arc electrode,
The YAG laser transmitted through the two optical fibers is
It has an optical system that focuses on each of the two beam spots,
A laser head that irradiates one beam in front of the arc electrode and the other beam behind the arc electrode, and a gas nozzle that supplies an inert gas such as argon or helium coaxially with the arc electrode of the arc torch. A laser-arc combined welding apparatus characterized by the above-mentioned. 10. An arc torch for holding an arc electrode, and an optical system for converging a YAG laser transmitted via one optical fiber to two beam spots by a beam splitter, and using one of the beams for arc irradiation. A laser head for irradiating the other beam behind the arc electrode in front of the electrode, and a gas nozzle for supplying an inert gas such as argon or helium coaxially with the arc electrode of the arc torch are provided. Laser-arc combined welding equipment.