JP2002144065A - Method for laser welding and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for laser welding by which a put-together hands shaped lapped joints are excellently welded from the outer side of rounded parts, and equipment therefor. SOLUTION: The vicinity of the rounded parts of the put-together hands shaped lapped joints 5 and 6 is heated with sub-laser beams 20 and 30, layers 21 and 31 in which a change in structure occurs is formed, thus the gap between the joints 5 and 6 is narrowed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method and an apparatus therefor, and more particularly to a laser welding method and an apparatus for a worship type joint in which a metal plate is bent and butt-joined.

[0002]

2. Description of the Related Art In recent years, with the advance of laser welding technology, various members and portions having various shapes have been used for laser welding. Common laser welding includes lap welding, butt welding, and dovetail joint welding.

[0003] In these laser weldings, one of the factors that determine the quality is the distance between the members to be welded, and it is important to keep this distance within an allowable range in order to perform good welding.

For example, in overlap welding, as shown in FIG. 5, the gap between the welded members 51 and 52 is corrected by pressing the overlapped welded members 51 and 52 from the upper plate 52 side by a rotating roller 54. Meanwhile, the laser beam 53 is applied to the welding portion by the laser welding machine 55 to perform welding.

In the butt welding, as shown in FIG. 6, the butt-welded members 61 and 62 are pressed by jigs 65 and 66 having sufficiently high rigidity to thereby form the butt-welded members 61 and 62. The gap is corrected and the laser welding machine 55
The laser beam 53 is radiated to the welding portion to perform welding.

In the case of a worship type joint, for example, according to the technique disclosed in Japanese Patent Application Laid-Open No. 10-225785, as shown in FIG. The gap between the members to be welded 71 and 72 is corrected by the sandwiching jig 75, and welding is performed from the inside of the worship type joint, that is, from the side where the planar members are in abutted state.

As described above, at the time of laser welding, the gap between the members to be welded is corrected by means for mechanically applying a force so that appropriate welding can be performed.

[0008]

However, in laser welding of a worship type joint, there is a case where the inside of the R (R) portion is a closed space. Not only those that can be welded.

In the case of a space in which the inside of the R is closed or a structure in which the jig cannot be inserted inside, a portion which is not only weldable from the inside but also becomes a worship type joint is mechanically interposed. It is also difficult to correct. For this reason, there has been a problem that the gap is opened more than an allowable size at the time of laser welding, resulting in poor welding.

Therefore, an object of the present invention is to provide a worship type joint with an R
An object of the present invention is to provide a laser welding method capable of appropriately welding from the outside of a portion.

It is another object of the present invention to provide a laser welding method and a laser welding method capable of satisfactorily welding a worship type joint from the outside of an R portion.

[0012]

The object of the present invention is achieved by the following constitution.

(1) A laser welding method for a worship joint, which comprises an auxiliary heating step of heating the vicinity of an R portion at a welding portion of the worship joint before irradiation with a welding laser. Laser welding method.

(2) In the auxiliary heating step, the width is １ ／ of the plate thickness from the top of the R portion of the welding portion to the stop of the R portion.
(1) The step of forming a structure-changed layer in which the structure of the member to be welded is changed in a range of up to 3.5 times and a depth of 2/5 to 3/5 of the plate thickness. Laser welding method.

(3) The auxiliary heating step is performed in a range of 10 to 50 J.
The laser welding method according to (1) or (2), wherein the step of applying an energy of / mm to the vicinity of the R portion.

(4) The laser welding method according to (2), wherein the structure change layer has a phase transformation structure.

(5) The laser welding method according to (2), wherein the structure change layer is a melt-solidified structure.

(6) A laser irradiation means for welding, and an auxiliary heating means for heating the vicinity of the R portion in the welding portion of the dovetail joint before welding by the laser irradiation means for welding. Laser welding equipment.

(7) The auxiliary heating means is 10 to 50 J
The laser welding apparatus according to (6), wherein an energy of / mm is applied to the vicinity of the R portion.

(8) The laser welding apparatus according to (6) or (7), wherein the auxiliary heating means is a laser.

(9) The laser is an Nd: YAG laser, and the laser light output of the Nd: YAG laser has a spot diameter of 0.45 to 8 mm and a laser output of 0.8 to 3.5 k.
(8) The laser welding apparatus according to (8), wherein the laser beam is irradiated to the vicinity of the R portion for heating in a range of W and a heating time of 0.0054 to 0.096 seconds.

[0022]

According to the laser welding method according to the first aspect of the present invention, before the irradiation of the welding laser, the vicinity of the R portion in the welded portion of the joint type joint is auxiliary-heated.
Due to this auxiliary heating, the vicinity of the R portion undergoes a structural change and expands, and the gap at the mating portion of the joint is narrowed, so that good welding can be performed.

According to the laser welding method according to the second aspect of the present invention, the width of the welded portion is 1/2 to 3.5 times the plate thickness from the top of the R portion to the stop of the R by the auxiliary heating. Since the structure change layer in which the structure of the member to be welded is changed is formed in a depth range of 2/5 to 3/5 of the plate thickness, the member to be welded is effectively expanded by the structure change layer. As a result, it is possible to narrow the gap at the mating portion of the worship joint, and to perform good welding of the worship joint.

According to the laser welding method according to the third aspect of the present invention, as the auxiliary heating step, heating is performed by applying an energy of 10 to 50 J / mm to the vicinity of the R portion. It is possible to form a structure change layer in the joint and narrow the gap at the joint of the worship type joint,
Good welding of the worship type joint can be performed.

According to the laser welding method according to the fourth aspect of the present invention, since the structure change layer has a phase-transformed structure, it is possible to effectively reduce the gap at the joint portion of the worship joint. Good joints can be welded.

According to the laser welding method according to the fifth aspect of the present invention, since the structure-change layer is made of a melt-solidified structure, it is possible to effectively narrow the gap between the joints of the worship joint. Good joints can be welded.

According to the laser welding apparatus according to the sixth aspect of the present invention, before the welding by the welding laser irradiation means, the auxiliary heating means for heating the vicinity of the R portion in the welded portion of the joint is provided. By the auxiliary heating by the auxiliary heating means, a structure change is caused in the vicinity of the R portion to cause expansion, thereby making it possible to narrow the gap at the mating portion of the wedge-shaped joint and to perform good welding.

According to the laser welding apparatus of the present invention, since the auxiliary heating means heats the vicinity of the R portion by applying an energy of 10 to 50 J / mm, the R portion can be effectively formed. Structural change is caused in the vicinity to expand the structure, thereby making it possible to narrow the gap at the mating portion of the worship type joint, and to perform good welding.

According to the laser welding apparatus of the present invention, the laser is used as the auxiliary heating means, so that the laser beam for laser welding can be used as the auxiliary heating means, so that it is easy to improve the laser welding. Welding can be performed.

According to the laser welding apparatus according to the ninth aspect of the present invention, the Nd: YAG laser is used for the Nd: YAG laser.
The laser beam output of the AG laser is adjusted to a spot diameter of 0.45 to 8
mm, a laser output of 0.8 to 3.5 kW, and a heating time of 0.0054 to 0.096 seconds. When used, it is possible to surely cause a change in the structure near the R portion and expand the structure, thereby making it possible to narrow the gap between the mating portions of the worship joint, and to perform good welding.

[0031]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a view showing a main part of a laser welding apparatus to which the present invention is applied, and FIG. 2 is an enlarged view of a cross section of a welded part.

FIG. 1 shows a laser welding apparatus to which the present invention is applied.
As shown in FIG. 7, the welded members 5 and 6 which are formed by bending a metal plate and butting against a dowel shape are to be welded from the outside of the R portion of the dovetail shape. The main laser emitting unit 1 for emitting a main laser beam 10 for performing actual welding
And auxiliary laser beams 20 and 3 for gap correction described later.
It has two sub-laser emitting units 2 and 3 for emitting 0, and a case 4 for supporting and storing these sub-laser emitting units 2 and 3.

Each of the laser emitting units 1, 2, and 3 is provided with a laser light source (not shown), similarly to a normal laser welding machine.
The output energy of the laser light emitted from each of the laser emitting units 1, 2, and 3 is controlled by a controller (not shown) connected to the laser light source. ing.

Next, a description will be given of a laser welding method for a worship type joint using the laser welding apparatus.

First, before irradiation of the main laser for welding, the members to be welded 5 and 6 are irradiated with the sub-laser beams 20 and 30.
Is heated in the vicinity of the R portion to form the structure change layers 21 and 31. This heating step is called an auxiliary heating step.

As shown in FIG. 2, the structure-changed layers 21 and 31 formed by the auxiliary heating step have a width L equal to 板 of the plate thickness from the top of the R portion of the welded portion to the R stop.
It is preferable that the depth D is in the range of 2/5 to 2/5 of the plate thickness (see Example below). By changing the structure in this range, the gap at the joint of the worship joint becomes narrower due to expansion due to the change in structure, and an appropriate gap tolerance can be set. The term "R stop" refers to a boundary between a curved R portion of a member to be welded and a straight portion having no curvature, and the R portion apex is a center between one R stop and the other R stop of the member to be welded. Say The width of the structure-changed layer by heating refers to the length in the direction perpendicular to the thickness direction of the layer whose structure has been changed by heating.

In order to obtain a texture change layer in such a range, as will be understood from the results of the examples described later, when a Nd: YAG laser is used as the laser of 0.45-8 mm, laser power 0.8-3 kW, and heating time 0.0054
It is preferable to heat in a range of 0.096 seconds. The amount of energy applied at this time is about 10 to 50 J / mm.
It has become.

Therefore, even when using a laser other than the Nd: YAG laser, for example, a carbon dioxide gas laser, it is possible to form an organization change layer by applying energy of about 10 to 50 J / mm and heating the vicinity of the R portion. Is possible. Similarly, about 10 to 10 by heating means other than laser.
It can be implemented even when an energy of 50 J / mm is applied.

After the formation of such a structure change layer, welding is performed by the main laser beam 10 from the main laser emitting section 1. At this time, the gap between the members to be welded 5 and 6 is within the allowable range due to the formation of the structure change layers 21 and 31, so that a good weld bead 11 is formed.

Here, the structure changing layer means that the structure of the material changes to a structure different from that before heating.
For example, it becomes a phase transformation structure or a melt-solidified structure. The phase transformation structure refers to a structure in which the structure of the material has changed due to transformation of the phase by heating from the structure before heating,
The melt-solidified structure refers to a changed structure in which the structure of the material has changed by melting and solidifying by heating from the structure before heating.

Since the vicinity of the R portion expands due to such a structural change, unlike the mere thermal expansion or the like, after the auxiliary heating is completed, that is, even when the auxiliary heated portion is cooled, the gap of the worship type joint is welded. The condition suitable for is maintained.

Next, the operation of this embodiment will be described.

FIG. 3 shows the case where the output of the auxiliary laser beam is 1 kW, the spot diameter is 0.45 mm, and the laser beam is irradiated while moving at the scanning speed of 3 to 7 m / min to the apex of the R-shaped joint. FIG. 3 is a drawing for explaining the amount of deformation.
FIG. 3A schematically shows the irradiation position and the state of the laser beam when one of the members 6 of the worship joint is irradiated with the laser beam 30 ′, and FIG. 3B shows the amount of deformation of the member to be welded with respect to the scanning speed. Here, as shown in FIG. 3A, the amount of deformation is indicated by “−” in the direction in which the gap of the worship-type joint is reduced, and “+” in the direction in which the gap is expanded.

As can be seen from FIG. 3B, a maximum deformation of about 0.5 mm occurs in the "-" direction due to the auxiliary heating. The gap between the two welded members of the worship type joint is usually less than 1 mm when they are fitted together without using a special jig. Therefore, a maximum of 0.5 mm
If it can be obtained, the members on both sides are deformed by about 1 mm, and the clearance of the worship joint is sufficiently reduced.

FIG. 4 shows that the output of the auxiliary laser beam is 3 kW, the spot diameter is 8 mm (the defocus state where the focus is weakened), and the scanning speed is 2 to 7 m / sec.
FIG. 4A is a view for explaining the amount of deformation when irradiating laser light while moving the laser beam at a distance of min. FIG. 4B shows the deformation amount of the member to be welded with respect to the scanning speed. Fig. 4
As shown in A, the direction in which the gap of the worship type joint is narrowed is “−”, and the direction in which the gap is widened is “+”.

As can be seen from FIG. 4B, the shape is deformed in the "-" direction by a maximum of about 0.4 mm by the auxiliary heating.
When the scanning speed is reduced, at 1 m / min, the surface is in a molten state, which is not preferable. At 2 m / min, the surface does not melt, but is deformed in the “+” direction, that is, the direction in which the gap is widened. I have. The result is that if the scanning speed is reduced and the amount of energy applied to the member to be welded is increased, the surface of the member to be welded may be melted, or the desired deformation may not be obtained without melting. It indicates that there is. On the other hand, by adjusting the amount of energy applied to the member to be welded as an appropriate value of the scanning speed,
The deformation amount can be about 0.4 mm at the maximum, and it is possible to obtain an optimum amount of energy for narrowing the gap of the worship joint.

[0048]

EXAMPLES Next, examples and comparative examples in which welding of a joint of a worship type were actually performed under various conditions in accordance with the above-described embodiment will be described.

Example 1 Mild steel plates having a thickness of 1.6 mm were used as the members 5 and 6 to be welded as the worship type joint, and the radius of curvature of the bent portion of the worship type was formed to 5 mm on the inner side. Butted.

For the members 5 and 6 to be welded, Nd: Y with a laser output of 1 kW is output from the sub-laser emitting portions 2 and 3.
Using an aG laser, laser beams 20 and 30 condensed to a spot diameter of 0.45 mm were irradiated at a scanning speed of 5 m / min to a position shifted by 2 mm from the end of R to the direction of the apex of the R portion.

Subsequently, Nd: YaG laser light 10 having a laser output of 2 kW was irradiated from the main laser emitting portion 1 while moving at the same scanning speed of 5 m / min as described above.
As a result, a weld bead 11 is formed, and the workpiece 5
And 6 were joined as a dovetail joint.

When the welded portion was visually evaluated, it was found that a weld bead having no perforation or the like and a good build-up state was obtained, and the weld was surely welded.

Embodiment 2 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was carried out under the same conditions as in Example 1 except that the irradiation position of 0 was 0 mm in the direction from the stop of R to the vertex of the R portion. As a result, although the width and depth of the structure-changed layers 21 and 31 were slightly changed, the weld bead portion was found to have a sound weld with no holes as a result of a visual inspection.

Embodiment 3 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 1 except that the irradiation position of 0 was 4 mm from the stop of R to the top of the R portion. As a result, although the width and depth of the structure-changed layers 21 and 31 were slightly changed, the weld bead portion was found to have a sound weld with no holes as a result of a visual inspection.

Embodiment 4 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was carried out under the same conditions as in Example 1 except that the laser output of 0 was set to 0.8 kW. As a result, although the widths and depths of the microstructure-changed layers 21 and 31 were slightly smaller than those in Example 1, as a result of a visual inspection, a sound weld without any perforations was formed in the weld bead portion.

Embodiment 5 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 1 except that the laser output of No. 0 was set to 1.6 kW. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly larger than those in Example 1, as a result of the visual inspection, a sound weld without a hole was formed in the weld bead portion.

Embodiment 6 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 1 except that the scanning speed of 0 was 4.0 m / min. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly larger than those in Example 1, as a result of the visual inspection, a sound weld without a hole was formed in the weld bead portion.

Embodiment 7 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 1 except that the scanning speed of 0 was set to 6.0 m / min. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly larger than those in Example 1, as a result of the visual inspection, a sound weld without a hole was formed in the weld bead portion.

Comparative Example 1 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 1 except that the irradiation position of 0 was 5 mm from the stop of R to the direction of the apex of the R portion. As a result, the widths and depths of the structure-changed layers 21 and 31 were greatly reduced, and as a result of a visual inspection, a hole was formed in the weld bead portion, and sound welding could not be performed.

Comparative Example 2 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The irradiation position of 0 is -3 mm from the end of R to the top of the R part.
The welding was performed under the same conditions as in Example 1 except that the welding was performed. As a result, although a structure-changed layer was obtained, the gap of the butt was not sufficiently reduced, and as a result of a visual inspection, a hole was formed and sound welding could not be performed.

Comparative Example 3 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 1 except that the laser output of 0 was set to 12 kW. As a result, the structure change layer penetrated the member to be welded and was deformed in a direction in which the gap of the butt was widened, so that no weld bead was formed and welding could not be performed.

Comparative Example 4 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
Except that the laser power of 0 was set to 0.05 kW,
The welding was performed under the same conditions as in Example 1. As a result, a microstructure-changed layer was hardly formed, and as a result of the visual evaluation, a hole was formed in the weld bead portion, so that sound welding could not be performed.

Comparative Example 5 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
Except that the scanning speed of 0 was set to 30 m / min,
The welding was performed under the same conditions as in Example 1. As a result, a microstructure-changed layer was hardly formed, and as a result of the visual evaluation, a hole was formed in the weld bead portion, so that sound welding could not be performed.

Comparative Example 6 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
Except that the scanning speed of 0 was set to 30 m / min,
The welding was performed under the same conditions as in Example 1. As a result, the structure change layer penetrated the member to be welded and was deformed in a direction in which the gap of the butt was widened, so that no weld bead was formed and welding could not be performed.

Example 8 Mild steel plates having a thickness of 1.6 mm were used as the welded members 5 and 6 to be welded as the worship-type joints in the same manner as in the first embodiment. Is formed to 5 mm on the inner side and butted. The Nd: YaG laser having a laser output of 3 kW is applied to the members to be welded 5 and 6 from the sub-laser emitting units 2 and 3 using a spot diameter of 8 m.
m and defocused laser beams 20 and 3
Irradiation was carried out at a scanning speed of 6 m / min at a scanning speed of 6 m / min to a position shifted by 2 mm in the direction of the R portion apex from the R stop.

Subsequently, Nd: YaG laser light 10 having a laser output of 2 kW was emitted from the main laser emitting section 1 while moving at the same scanning speed of 5 m / min as described above.
As a result, a weld bead 11 is formed, and the workpiece 5
And 6 were joined as a dovetail joint.

When the welded portion was visually evaluated, it was found that a weld bead having no perforation or the like and a good build-up state was obtained, and the weld was surely welded.

Embodiment 9 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the irradiation position of 0 was 0 mm from the stop of R to the top of the R portion. As a result, although the width and depth of the structure-changed layers 21 and 31 were slightly changed, the weld bead portion was found to have a sound weld with no holes as a result of a visual inspection.

Embodiment 10 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the irradiation position of 0 was 4 mm from the stop of R to the top of the R portion. As a result, although the width and depth of the structure-changed layers 21 and 31 were slightly changed, the weld bead portion was found to have a sound weld with no holes as a result of a visual inspection.

Embodiment 11 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the laser output of the laser beam of 0 was set to 2.5 kW. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly smaller than those in Example 8, as a result of the visual inspection, a sound welding without holes was formed in the weld bead portion.

Embodiment 12 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the laser output of the laser beam of 0 was set to 3.5 kW. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly larger than those in Example 8, as a result of the visual inspection, a sound weld having no holes was formed in the weld bead portion.

Embodiment 13 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the scanning speed of 0 was 5.0 m / min. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly larger than those in Example 8, as a result of the visual inspection, a sound weld having no holes was formed in the weld bead portion.

Embodiment 14 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the scanning speed of 0 was set to 7.0 m / min. As a result, although the widths and depths of the structure-changed layers 21 and 31 were slightly larger than those in Example 8, as a result of the visual inspection, a sound weld having no holes was formed in the weld bead portion.

Comparative Example 7 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the irradiation position of 0 was 5 mm from the stop of R to the direction of the apex of the R portion. As a result, the widths and depths of the structure-changed layers 21 and 31 were greatly reduced, and as a result of a visual inspection, a hole was formed in the weld bead portion, and sound welding could not be performed.

Comparative Example 8 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The irradiation position of 0 is -3 mm from the end of R to the top of the R part.
The welding was performed under the same conditions as in Example 8 except that the welding was performed. As a result, although a structure-changed layer was obtained, the gap of the butt was not sufficiently reduced, and as a result of a visual inspection, a hole was formed and sound welding could not be performed.

Comparative Example 9 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the laser output of 0 was set to 12 kW. As a result, the structure change layer penetrated the member to be welded and was deformed in a direction in which the gap of the butt was widened, so that no weld bead was formed and welding could not be performed.

Comparative Example 10 Laser Lights 20 and 3 from Sub-Laser Emitting Units 2 and 3
Except that the laser power of 0 was set to 0.05 kW,
Welding was performed under the same conditions as in Example 8. As a result, a microstructure-changed layer was hardly formed, and as a result of the visual evaluation, a hole was formed in the weld bead portion, so that sound welding could not be performed.

Comparative Example 11 Laser beams 20 and 3 from sub-laser emitting units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the scanning speed of 0 was set to 600 m / min. As a result, a microstructure-changed layer was hardly formed, and as a result of the visual evaluation, a hole was formed in the weld bead portion, so that sound welding could not be performed.

COMPARATIVE EXAMPLE 12 Laser Lights 20 and 3 from Secondary Laser Emitting Units 2 and 3
The welding was performed under the same conditions as in Example 8 except that the scanning speed of 0 was set to 0.1 m / min. As a result, the structure change layer penetrated the member to be welded and was deformed in a direction in which the gap of the butt was widened, so that no weld bead was formed and welding could not be performed.

Tables 1 and 2 summarize the conditions of the above Examples and Comparative Examples and the results of the visual evaluation. Table 1 shows Examples 1 to 7 and Comparative Examples 1 to 6, and Table 2 shows Examples 8 to 14 and Comparative Examples 7 to 12.

[0081]

[Table 1]

[0082]

[Table 2]

From the results of these Examples and Comparative Examples,
It can be seen that it is effective to heat the R portion of the worship joint from the outside with the sub-laser and change the structure of that portion in order to perform laser welding of the worship joint satisfactorily.

In particular, the heating range is such that the width L is １ ／ of the plate thickness from the top of the R portion of the welded portion to the stop of the R portion.
It can be seen that the depth D is preferably in the range of 1/3 to 2/3 of the plate thickness. The irradiation output of the sub-laser light is as follows: when an Nd: YAG laser is used, the laser spot diameter is 0.45 to 8 mm, and the laser output is 0.8 to 3 k.
It is understood that it is preferable to heat W and the heating time in the range of 0.0054 to 0.096 seconds.

From these results, the energy applied to the member to be welded as auxiliary heating is, as the lower limit, (800 (W) / ((0.45 (mm) / 2) ² ×
π)) × 0.0054 (sec) × 0.45 (mm) =
12.2 (J / mm)

The upper limit is (3000 (W) / ((8 (mm) / 2) ² × π)) ×
0.096 (sec) × 0.8 (mm) = 45.9 (J
/ Mm).

Therefore, by applying an energy of about 10 to 50 J / mm, preferably about 12 to 46 (J / mm) to the vicinity of the R portion of the member to be welded, a desired structure change layer is formed, and an appropriate welding is performed. Can be performed.

Although the embodiments and examples to which the present invention is applied have been described above, the present invention is not limited to such embodiments and examples.

For example, in the above-described embodiment, the main laser emitting section for performing the laser welding and the sub-laser sub-laser emitting section for performing the auxiliary heating are separately provided. The present invention can be implemented even with a laser welding device having a part. In this case, first, before the laser welding, the output of the laser beam is set to about 10 to 50 J.
The auxiliary heating is performed by adjusting the energy of / mm to be applied to the vicinity of the R portion of the member to be welded, and then the output of the laser beam is adjusted to the energy for welding to perform the welding. In this case, there is no need to prepare a separate laser device as the auxiliary heating means, so that the present invention can be easily implemented.

In the present invention, as described above,
Since the gap is narrowed by causing a structural change in the welded member by the auxiliary heating, the auxiliary heating is performed by one laser beam, and even if the auxiliary heating part cools before welding is performed, the width is reduced. Since the gap is left as it is, sufficiently good welding can be performed.

Further, as the auxiliary heating means, about 10 to
As long as the energy of 50 J / mm can be applied to the vicinity of the R portion of the member to be welded, a gas burner or the like may be used instead of the laser beam.

[Brief description of the drawings]

FIG. 1 is a drawing showing a main part of a laser welding apparatus to which the present invention is applied.

FIG. 2 is an enlarged view of a cross section of a welded portion.

FIG. 3 shows an output of a sub laser beam of 1 kW and a spot diameter of 0.1 kW.
It is 45 mm and is a figure for demonstrating the deformation | transformation amount when irradiating a laser beam, moving at the scanning speed of 3-7 m / min with respect to the R part vertex of a dovetail joint.

FIG. 4 shows an output of a sub laser beam of 3 kW and a spot diameter of 8 m.
m, and scanning speed 2 to 7 with respect to the apex of the R-shaped joint
It is a drawing for explaining an amount of deformation when irradiating a laser beam while moving at m / min.

FIG. 5 is a view showing a conventional lap welding method.

FIG. 6 is a view showing a conventional butt welding method.

FIG. 7 is a view showing a method of welding an end of a conventional worship type joint from the inside.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Main laser emission part, 2, 3 ... Sub-laser emission part, 4 ... Sub-laser emission part storage case, 5, 6 ... Member to be welded, 10 ... Main laser beam, 11 ... Weld bead, 20, 30, 30 ' .., 30 ″... Sub-laser beam, 21, 31.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Osamu Niikura Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Minoru Kasukawa Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture F Term (reference) 4E068 AA05 AH01 AJ03 BD00 DA14 DB01

Claims (9)

[Claims] 1. A laser welding method for a worship joint, comprising an auxiliary heating step of heating the vicinity of an R portion at a welding portion of the worship joint before irradiation with a welding laser. Laser welding method. 2. The method according to claim 1, wherein the auxiliary heating step includes:
Between the top of the part and the R stop, the width is 1/2 of the plate thickness
2. The laser according to claim 1, wherein said step is a step of forming a structure-changed layer in which the structure of the member to be welded is changed in a range of 3.5 times and a depth of 2/5 to 3/5 of the plate thickness. Welding method. 3. The method according to claim 1, wherein the auxiliary heating step is performed at 10 to 50 J / m.
3. The laser welding method according to claim 1, wherein the step of applying m energy to the vicinity of the R portion. 4. The laser welding method according to claim 2, wherein the structure change layer has a phase transformation structure. 5. The laser welding method according to claim 2, wherein the structure change layer is a melt-solidified structure. 6. A laser irradiation means for welding, and an auxiliary heating means for heating the vicinity of an R portion at a welding portion of the joint, before welding by the laser irradiation means for welding,
A laser welding apparatus comprising: 7. The auxiliary heating means may be 10 to 50 J / m.
7. The laser welding apparatus according to claim 6, wherein m energy is applied to the vicinity of the R portion. 8. The laser welding apparatus according to claim 6, wherein said auxiliary heating means is a laser. 9. The laser is an Nd: YAG laser, and the laser light output of the Nd: YAG laser has a spot diameter of 0.45 to 8 mm, a laser output of 0.8 to 3.5 kW, and a heating time of 0.1 to 3.5 kW. 9. The laser welding apparatus according to claim 8, wherein a laser beam is irradiated to the vicinity of the R portion for heating in a range of 0054 to 0.096 seconds.