JP7547145B2 - Laser welding method and laser welding apparatus - Google Patents

Description

The present invention relates to a laser welding method and a laser welding device.

As one method for welding objects made of metallic materials, a laser welding method and laser welding device are known in which a filler wire is supplied onto the surface of the object while a laser beam is irradiated to perform welding (for example, Patent Document 1).

International Publication No. 2020/026750

In this type of laser welding, the number of parameters to be set, such as the diameter of the filler wire, increases compared to laser welding that does not use a filler wire, so it can take longer to set each parameter to prevent welding defects such as bead cracks and spatters.

Therefore, one of the objectives of the present invention is to provide a new and improved laser welding method and laser welding apparatus that enables easier laser welding with fewer welding defects, for example, in laser welding in which a laser beam is irradiated while a filler wire is supplied.

The laser welding method of the present invention is, for example, a laser welding method in which a filler wire is supplied onto the surface of an object, and a laser beam is irradiated onto the surface in a sweeping direction relative to the object, thereby melting the filler wire and welding the object, and the width ratio, which is the ratio of the width of the laser beam on the surface in a direction perpendicular to the sweeping direction to the diameter of the filler wire, is 0.8 or more.

In the laser welding method, the width ratio may be 4 or less.

In the laser welding method, the width ratio may be greater than or equal to 1.5 and less than or equal to 3.6.

In the laser welding method, the laser light may have an annular first power region.

In the laser welding method, the laser light may have a second power region surrounded by a first power region.

In the laser welding method, the laser light has a first power region and a second power region whose width in a direction perpendicular to the sweep direction is narrower than that of the first power region, and the first power region may be at least partially located forward of the second power region in the sweep direction.

In the laser welding method, a power ratio, which is the ratio of the power of the laser light in the second power region to the power of the laser light in the first power region, may be greater than or equal to 0 and less than or equal to 9.

In the laser welding method, the power ratio may be greater than or equal to 3/7 and less than or equal to 7/3.

In the laser welding method, the filler wire may be disposed at a position where the laser light that forms the first power region is irradiated, and may be disposed at a position different from a position where the laser light that forms the second power region is irradiated.

In the laser welding method, the first power region may include multiple beams of the laser light.

In the laser welding method, the multiple beams may be arranged in a circular ring shape.

In the laser welding method, the multiple beams may be arranged in a rectangular ring shape.

In the laser welding method, the laser light may include multiple beams, and the multiple beams may be formed by a beam shaper.

In the laser welding method, the beam shaper may be a diffractive optical element.

In the laser welding method, the filler wire is positioned so as to be in contact with a molten pool formed on the surface, and a first end of the filler wire that is in contact with the molten pool and is close to the surface is spaced apart in a first direction from the irradiation center of the laser light on the surface, and a second end of the molten pool in the first direction is located farther away from the irradiation center in the first direction than the first end.

In the laser welding method, the first direction may be the sweep direction.

In the laser welding method, the laser light and the filler wire may be swept in the first direction relative to the surface.

The laser welding device of the present invention is, for example, a laser welding device that includes an optical head that irradiates a surface of an object with laser light and a filler wire supply unit that supplies a filler wire onto the surface, and that melts the filler wire and welds the object by irradiating the surface with the laser light in a sweeping direction relative to the object, and the width ratio, which is the ratio of the width of the laser light on the surface in a direction perpendicular to the sweeping direction to the diameter of the filler wire, is 0.8 or more.

The present invention provides, for example, an improved and novel laser welding method and laser welding apparatus.

FIG. 1 is an exemplary schematic configuration diagram of a laser welding apparatus according to an embodiment. FIG. 2 is a schematic and exemplary side view of a welded portion in the laser welding method of the embodiment. FIG. 3 is an explanatory diagram showing the concept of the principle of the diffractive optical element included in the laser welding apparatus of the embodiment. FIG. 4 is a schematic diagram showing an example of a beam (spot) of laser light irradiated from the laser welding apparatus of the embodiment on the surface of an object. FIG. 5A is a plan view showing an example of a bead formed on a surface of an object by the laser welding method of the embodiment. FIG. 5B is a plan view showing an example of a bead formed on a surface of an object by the laser welding method of the embodiment. FIG. 5C is a plan view showing an example of a bead formed on a surface of an object by the laser welding method of the embodiment. FIG. 5D is a plan view showing an example of a bead formed on a surface of an object by the laser welding method of the embodiment. FIG. 6 is a schematic diagram showing another example of a beam (spot) on the surface of an object of the laser light irradiated from the laser welding apparatus of the embodiment.

Below, exemplary embodiments of the present invention are disclosed. The configurations of the embodiments shown below, and the actions and results (effects) brought about by said configurations, are merely examples. The present invention can also be realized with configurations other than those disclosed in the following embodiments. Furthermore, according to the present invention, it is possible to obtain at least one of the various effects (including derivative effects) obtained by the configurations.

In addition, in each figure, the direction X is represented by an arrow X, the direction Y is represented by an arrow Y, and the direction Z is represented by an arrow Z. The directions X, Y, and Z intersect with each other and are perpendicular to each other. The Z direction is the normal direction of the surface Wa (machined surface) of the object W, and is the opposite direction to the irradiation direction of the laser light L.

In addition, in this specification, ordinal numbers are used for convenience to distinguish between parts, materials, locations, areas, processes, etc., and do not indicate priority or order.

[Embodiment]
[Configuration of laser welding device]
Fig. 1 is a diagram showing a schematic configuration of a laser welding apparatus 100 according to an embodiment. As shown in Fig. 1, the laser welding apparatus 100 includes a laser device 110, an optical head 120, an optical fiber 130, and a supply mechanism 140 for a filler wire F.

The laser welding device 100 irradiates the surface Wa of the object W with laser light L and supplies a filler wire F onto the surface Wa. The object W and the filler wire F are melted and solidified by the energy of the laser light L, thereby welding the object W.

The object W has multiple components (not shown), which are joined by laser welding.

The multiple components that make up the target object W can each be made of, for example, an iron-based metal material such as iron or an iron alloy, an aluminum-based metal material such as aluminum or an aluminum alloy, or a copper-based metal material such as copper or a copper alloy. The multiple components may be made of the same metal material, or may be made of different metal materials.

Filler wire F, also known as filler metal, is a wire-shaped metal material added during welding. Filler wire F offers the advantage of being able to supply metal material to fill gaps between multiple components when those gaps exist, and can supply an additive that suppresses the formation of intermetallic compounds that weaken the joint strength when the multiple components are made of dissimilar metals.

The laser device 110 is equipped with a laser oscillator and is configured to output, for example, a single-mode laser beam with a power of several kW. The laser device 110 may be configured to include, for example, multiple semiconductor laser elements therein and to output a multi-mode laser beam with a power of several kW as the total output of the multiple semiconductor laser elements. The laser device 110 may also be equipped with various laser light sources, such as a fiber laser, a YAG laser, or a disk laser.

The optical fiber 130 optically connects the laser device 110 and the optical head 120. In other words, the optical fiber 130 guides the laser light output from the laser device 110 to the optical head 120. When the laser device 110 outputs a single mode laser light, the optical fiber 130 is configured to propagate the single mode laser light. In this case, the ^M2 beam quality of the single mode laser light is set to 1.3 or less. The ^M2 beam quality may also be referred to as an M2 factor.

The optical head 120 is an optical device for irradiating the laser light input from the laser device 110 toward the object W. The optical head 120 includes a collimator lens 121, a condenser lens 122, and a DOE 123 (diffractive optical element). The collimator lens 121, the condenser lens 122, and the DOE 123 may also be referred to as optical components. Note that the optical components included in the optical head 120 are not limited to the collimator lens 121, the condenser lens 122, and the DOE 123.

The optical head 120 is configured to be able to change its relative position with respect to the object W in order to sweep the laser light L over the surface Wa. The relative movement between the optical head 120 and the object W can be achieved by moving the optical head 120, moving the object W, or moving both the optical head 120 and the object W. By the relative movement between the optical head 120 and the object W, the irradiation position of the laser light L moves in the sweep direction SD on the surface Wa of the object W. Note that in this embodiment, a case where the sweep direction SD is the X direction is illustrated as an example.

The collimating lens 121 collimates the input laser light. The collimated laser light becomes parallel light. The focusing lens 122 focuses the parallel laser light and irradiates the laser light as laser light L (output light) onto the target W.

The DOE 123 is disposed between the collimator lens 121 and the focusing lens 122, and shapes the shape of the laser light beam (hereinafter referred to as the beam shape).

The filler wire F supply mechanism 140 has a feed device 141 and a nozzle 142. The feed device 141 feeds out the filler wire F at a set constant speed. The nozzle 142 feeds out the filler wire F fed out from the feed device 141 at a set angle toward a set position on the surface Wa. The feed speed of the filler wire F from the feed device 141 can be set to be variable. The supply mechanism 140 is an example of a filler wire supply unit.

The nozzle 142 is configured to be stationary relative to the optical head 120. As an example, the nozzle 142 is fixed to the optical head 120 or a support member that movably supports the optical head 120.

Figure 2 is an enlarged side view of the welded area, and shows a schematic diagram of the state in which filler wire F is supplied onto the surface Wa and laser light L is irradiated to weld the area. Figure 2 is a view along the surface Wa and perpendicular to the sweep direction SD.

The optical head 120 and the nozzle 142 move together in the sweep direction SD along the surface Wa. The feed speed of the filler wire F in the feed device 141 is set appropriately so that the shape shown in FIG. 2 is maintained, that is, so that the filler wire F is neither oversupplied nor undersupplied to the welding site. As a result, the laser light L and the filler wire F move together in the sweep direction SD relative to the surface Wa while roughly maintaining the shape shown in FIG. 2.

The optical axis center of the laser light L and the central axis of the filler wire F are approximately aligned along the same XZ plane. The XZ plane is a plane that is aligned along the X direction and the Z direction, and is a plane that is aligned along the sweep direction SD and the irradiation direction of the laser light L.

The laser light L is irradiated to the surface Wa in the opposite direction to the Z direction. The filler wire F is supplied to the welding site in the supply direction S shown in FIG. 2. The supply direction S is a direction between the opposite direction of the sweep direction SD and the irradiation direction of the laser light L, that is, a direction between the opposite direction of the Z direction and the opposite direction of the X direction.

In addition, as an example, the supply position of the filler wire F is shifted in the sweep direction SD from the irradiation center C of the laser light L on the surface Wa.

As shown in FIG. 2, during welding, a liquid molten pool M is formed on the surface Wa by the irradiation of the laser light L, melting the object W and the filler wire F. As the laser light L moves in the sweep direction SD, the portion of the molten pool M that is outside the irradiation area of the laser light L is cooled and solidified. As a result, a bead B extends from the molten pool M on the surface Wa in the opposite direction to the sweep direction SD.

In the example shown in FIG. 2, during welding, the end face Fe of the filler wire F is in contact with the surface of the liquid molten pool M. The tip e2 of the molten pool M in the sweep direction SD is located farther away from the irradiation center C of the laser light L in the sweep direction SD than the lower end e1 of the end face Fe that is closer to the surface Wa. Experimental research by the inventors has revealed that when such a configuration is obtained during welding, the molten pool M is stable and a suitable welding state with few welding defects such as cracks, humping, and spatters in the bead B can be obtained. Note that FIG. 2 is an example of a welding state with few welding defects, and the configuration of the welded portion in a welding state with few welding defects is not limited to that shown in FIG. The sweep direction SD is an example of a first direction, the lower end e1 is an example of a first end, and the tip e2 is an example of a second end.

Figure 3 is an explanatory diagram showing the concept of the principle of the DOE 123. As shown in Figure 3, the DOE 123 has a configuration in which, for example, multiple diffraction gratings 123a with different periods are superimposed. The DOE 123 can shape the beam shape by bending the parallel light in a direction influenced by each diffraction grating 123a or by superimposing the light. The DOE 123 can also be called a beam shaper.

Figure 4 is a diagram showing an example of a beam (spot) of laser light L formed on the surface Wa of the object W. Note that, for simplicity, in Figure 4, the beam Lm is shown by a solid line and the beam Ls is shown by a dashed line.

DOE123 splits the laser light into multiple beams. The multiple beams include at least one beam Lm and at least one beam Ls. Beam Lm may also be referred to as a main beam, and beam Ls may also be referred to as a sub beam.

In the example of FIG. 4, the laser light L has one beam Lm and 16 beams Ls that surround the beam Lm in a circular ring shape. The beam Lm is positioned near the irradiation center of the laser light L, and the beam Ls is positioned farther from the irradiation center than the beam Lm. The region including the beam Lm is an example of the second power region A2, and the region including the beam Ls is an example of the first power region A1. Note that the number and arrangement of the beams Lm and beams Ls are not limited to the example of FIG. 4. By replacing the DOE 123, the optical head 120 can output laser light L including multiple beams in various arrangements.

As in the example of FIG. 4, when the laser light L includes a plurality of beams, the diameter Dl (width) of the laser light L is defined as the distance between the centers of the two beams Ls that are the furthest apart in the width direction. The width direction is a direction perpendicular to the sweep direction SD, which is the Y direction in this embodiment. Each beam Ls, Lm has, for example, a Gaussian-shaped power distribution along the radial direction on the surface Wa. In this case, the beam diameter of each beam Ls, Lm can be defined as the diameter of a region that includes the peak of the beam Ls, Lm and has an intensity of 1/e2 or ^more of the peak intensity. In addition, the center of each beam Ls, Lm can be the position of the intensity peak.

On the other hand, although not shown, when the laser light L includes only one beam having a Gaussian-shaped power distribution, the diameter of the laser light L can be defined as the diameter of a region that includes the peak of the beam and has an intensity equal to or greater than ¹ /e2 of the peak intensity.

By appropriately designing, setting, or adjusting the laser device 110, the optical fiber 130, the collimator lens 121, the focusing lens 122, and the DOE 123, the laser welding device 100 can output laser light L including the beam Lm and beam Ls as described above.

[Welding method]
In welding using the laser welding device 100, first, the object W and the filler wire F are set in an area to be irradiated with the laser light L. Then, in a state in which the laser light L including the beams Lm and Ls split by the DOE 123 is irradiated on the object W, the laser light L, the filler wire F, and the object W move relatively. As a result, the laser light L moves in the sweep direction SD on the surface Wa while being irradiated on the surface Wa, that is, the laser light L is swept on the surface Wa. In the portion irradiated with the laser light L, the object W and the filler wire F melt, and then solidify as the temperature decreases, thereby welding the object W. At this time, a bead B is formed. The bead B extends along the sweep trajectory. In the present embodiment, as an example, the sweep direction SD is the X direction, but the sweep direction SD may be any direction as long as it intersects with the Z direction, and is not limited to the X direction. Also, a curved sweep may be performed on the surface Wa, thereby forming a curved bead B.

In addition, in a series of experimental studies by the inventors, it was confirmed that by positioning at least a portion of the beam Ls (first power region A1) in the laser light L forward of the beam Lm (second power region A2) in the sweep direction SD, it is possible to suppress the occurrence of welding defects such as cracks in the bead B, humping, and spatters. This can be presumed to be because, for example, the molten pool M of the object W formed by the beam Ls and the beam Lm becomes more stable due to the preheating of the object W by the beam Ls before the arrival of the beam Lm.

[Experimental Results]
The inventors conducted an experiment to evaluate the welding state by actually performing laser welding on an object W by irradiating the object W with laser light L having the beam shape shown in Fig. 4 using the laser welding device 100. Table 1 shows the experimental results of the welding.

In the experiments, the material of the object W was stainless steel (SS400), and the filler wire F was carbon steel, copper-plated, whose main components were C, S, Mn, P, Si, Cr, Ni, Mo, V, and Cu, and is generally used for butt and all-position fillet welding of various welded structures using mild steel and 490 [N/ ^mm2 ] class high-tensile steel, such as automobiles, vehicles, home appliances, industrial machinery, light-weight steel, pipes, and steel frames.

The experiment was conducted on multiple samples of the object W, changing the width ratio and power ratio. The width ratio is the ratio of the diameter Dl (width, see FIG. 4) of the laser light L to the diameter Df (width, see FIG. 2) of the filler wire F, and is Dl/Df. The power ratio is the ratio of the total power Pm of the beam Lm (main beam) in the second power region A2 to the total power Ps of the beam Ls (sub-beam) in the first power region A1, and is Pm/Ps. The experiment was conducted for width ratios of 0.2, 0.8, 2.3, 2.7, 3.1, and 4, and for power ratios of 3/7, 1, 7/3, and 9. The experiment was also conducted for the cases of only the beam Ls (only the sub-beam) and only the beam Lm (only the main beam). The case of only the beam Ls (only the sub-beam) can be said to be a case of a power ratio of 0.

In addition, in all cases in the experiment, the wavelength of the laser light L output from the laser device 110 was set to 1070 [nm], the total power of the laser light L was set to 3.0 [kW], the welding speed was set to 0.5 [m/min], and the supply speed of the filler wire F was set to 1 [m/min]. In addition, the beam quality of the multimode fiber laser was a BPP value of 1.7 [mm mrad].

In Table 1, the welding condition is indicated by ◎ as excellent, ○ as good, and × as poor. Excellent (◎) means that there are no cracks or large irregularities (humping) in the bead B, the flow of the molten pool M is straight, and the number of spatters within the field of view of the high-speed camera is 10 or less [pieces/15 mm]; good (○) means that there are no cracks or large irregularities (humping) in the bead B, the flow of the molten pool M is straight, and the number of spatters within the field of view of the high-speed camera is 20 or less [pieces/15 mm]; and poor (×) means that the criteria for excellent and good are not met.

Note that Table 1 shows the experimental results for welding when the object W is a single plate material with a thickness of 100 mm, but it can be assumed that similar results can be obtained for other types of welding, such as welding multiple components with different thicknesses.

From the experimental results in Table 1 and related experimental results, it was found that the width ratio should be 0.8 or more, preferably 4 or less, more preferably 1.5 to 3.6, and even more preferably 2.3 to 3.1.

If the width ratio is less than 0.8, the density of light energy irradiated to the surface Wa of the object W and the filler wire F becomes excessive, which is believed to increase the vapor pressure of the molten metal in the molten pool M and cause the molten metal flow to become turbulent, resulting in defects such as spattering and poor bead appearance.

After repeated investigations focusing on these points, the inventors discovered that good welding quality can be obtained if the width ratio is 0.8 or more.

Furthermore, it was found that when the width ratio is 4 or less, the density of the light energy irradiated to the surface Wa of the object W and the filler wire F is sufficient, and the preheating effect and stabilization of the molten state can be obtained without increasing the light output.

Furthermore, when the ratio is 2.3 or more and 3.1 or less, the welding condition is stabilized, spatter is suppressed, and the efficiency of light irradiation energy is improved, which is found to be superior in terms of reducing costs in mass production processes.

In addition, when the width ratio is 1.5 or more and 3.6 or less, it was found that the welding condition was stabilized and spatter was suppressed, resulting in a good balance between the light energy density irradiated to the surface Wa of the target object W and the filler wire F and the preheating area.

In addition, the experimental results in Table 1 and related experimental results show that the power ratio is preferably 0 to 9, and more preferably 3/7 to 7/3.

When welding is performed using a beam that does not control the heat input distribution, for example, using only the main beam, the light energy density irradiated to the surface Wa of the workpiece W and the filler wire F becomes excessive, causing the vapor pressure of the molten metal in the molten pool M to increase and the flow of the molten metal to become turbulent. This leads to problems such as spatter generation and poor bead appearance.

When the power ratio, in which the heat input distribution was controlled by adding a secondary beam, was between 0 and 9, it was confirmed from high-speed camera images that the end face Fe of the filler wire F blended with the surface of the liquid molten pool M. However, when the power ratio of the secondary beam was high, the energy of the secondary beam caused the filler wire F to melt and drip in the form of liquid beads before it came into contact with the molten pool M.

As a result of repeated investigations of the heat input distribution, focusing on the melting stability of the filler wire F, the appearance of the bead, the stability of the molten pool M's molten metal flow, and the amount of spatter generated, it was found that better welding quality was obtained when the power ratio was 3/7 or more and 7/3 or less.

Within this power ratio range, the balance between the energy contributing to preheating and the energy contributing to melting is good, so the vapor pressure of the molten metal in the molten pool M is kept within a certain range, which has the effect of stabilizing the flow of the molten metal. As a result, there was no induction of defects such as spatter generation or poor bead appearance.

When the width ratio is 2.3 or more and 3.1 or less, and the power ratio is 3/7 or more and 7/3 or less, in addition to stabilizing the welding condition and suppressing spatter, there is a tolerance for misalignment of the target object W and filler wire F relative to the light irradiation position, which is superior in terms of reducing the rate of defects in the mass production process and long-term reliability.

Furthermore, in the experiment, it was found that when the energy density irradiated to the filler wire F is not excessively high, such as when the filler wire F is not irradiated with the beam Lm (second power region) and only a portion of the beam Ls (first power region), the molten pool M becomes more stable and welding defects such as cracking of the bead B, humping, and spattering are unlikely to occur. When the width ratio or power ratio is excessively small, the energy density of the laser light L irradiated to the filler wire F becomes high, causing the filler wire F to melt rapidly, which in turn makes the molten pool M unstable and makes welding defects more likely to occur.

Figures 5A to 5D are plan views of the bead B obtained on the surface Wa of the object W.

Figure 5A is a photographic image when the width ratio is 2.7 and the power ratio is 3/7. As shown in Figure 5A, under these conditions, there were no cracks or humps in bead B, and the surface of bead B was smooth. In addition, under these conditions, almost no spatter occurred.

Figure 5B is a photographic image when only the main beam is used. Under these conditions, the number of spatters within the field of view of the high-speed camera was approximately 21 to 100 [pieces/15 mm], and as shown in Figure 5B, variation in bead width was also confirmed, so it was rated as x. It is presumed that the cause of the spatters was that the light energy density irradiated to the surface Wa of the target object W and the filler wire F was too high, causing the molten metal flow in the molten pool M to become turbulent.

Figure 5C is a photographic image when only the secondary beam is used. Under these conditions, the number of spatters within the field of view of the high-speed camera was approximately 11 to 20 [pieces/15 mm]. Also, under these conditions, it was confirmed that the filler wire F melted into droplets and dripped before coming into contact with the molten pool M. It was confirmed that the excessive irradiation energy of the secondary beam caused the filler wire F to melt before coming into contact with the molten pool M, resulting in random dripping and a major issue with supply stability. As shown in Figure 5C, there was a lot of humping in the bead B, so it was rated as x.

Figure 5D is a photographic image when the width ratio is 2.3 and the power ratio is 9. Under these conditions, the number of spatters within the field of view of the high-speed camera was approximately 11 to 20 [pieces/15 mm]. As shown in Figure 5D, there was no humping of the bead B, so it was rated as good. It is presumed that by making the diameter Dl of the laser beam L on the surface Wa larger than the diameter Df of the filler wire F, the filler wire F and the molten pool blend well together, resulting in a preheating effect.

When the surface Wa is not a flat surface having steps, the width ratio, power ratio, etc. of the laser light L are defined in a virtual irradiation plane that includes the irradiation center C on the surface Wa of the laser light L and is perpendicular to the irradiation direction of the laser light L.

As explained above, the width ratio, which is the ratio of the width Dl in the direction perpendicular to the sweep direction SD on the surface Wa of the laser light L to the diameter Df of the filler wire F, is preferably 0.8 to 4, more preferably 1.5 to 3.6, and even more preferably 2.3 to 3.1.

Furthermore, as in this embodiment, the power ratio (Pm/Ps), which is the ratio of the power Pm of the laser light in the second power region A2 to the power Ps of the laser light in the first power region A1, is preferably 0 to 9, and more preferably 3/7 to 7/3.

The laser welding method and laser welding device 100 under these conditions have the effect of making it difficult for welding defects such as cracking of the bead B, humping, and spatter to occur. In addition, by setting the laser device 110, optical head 120, filler wire F supply mechanism 140, etc. to satisfy these conditions, it is possible to obtain the advantage that welding with fewer welding defects can be performed more easily, more quickly, or more reliably.

Also, as in this embodiment, the multiple beams Ls and Lm may be formed by a DOE 123 (beam shaper).

With this configuration, for example, it is possible to more easily form a laser light L having a plurality of beams Ls, Lm arranged in a predetermined layout. In addition, there is also the advantage that the arrangement of the beams Ls, Lm in the laser light L can be more easily changed by replacing the DOE 123.

In addition, the laser light of at least one beam Ls included in the first power region A1 and the laser light of at least one beam Lm included in the second power region A2 may be emitted from the same oscillator. In this case, the beam Ls and the beam Lm can be generated from the laser light emitted from a single oscillator.

In addition, the laser light of at least one beam Ls included in the first power region A1 and the laser light of at least one beam Lm included in the second power region A2 may be emitted from different laser oscillators. In this case, it becomes easier to set the characteristics of each of the beams Ls and Ls independently.

[Modification of Beam]
FIG. 6 is a diagram showing an example of a beam (spot) of the laser light L formed on the surface Wa of the object W. In the example of FIG. 6, the laser light L has one beam Lm and 24 beams Ls arranged along the sides of a rectangle. That is, the beams Ls arranged in a rectangular ring shape surround the beam Lm. The beam Lm is positioned near the irradiation center of the laser light L, and the beam Ls is positioned farther from the irradiation center than the beam Lm. Even with such an arrangement of the beams Ls, Lm, the density of the laser light L irradiated to the filler wire F is suppressed from becoming excessively high, the molten pool M is more stabilized, and welding defects are less likely to occur. Note that the beam Ls does not necessarily have to be annular, i.e., it does not have to cover the entire periphery of Lm, and may be arranged in the Y direction or in an arc shape in front of the sweep direction SD.

Although the above is an example of an embodiment of the present invention, the above embodiment is merely an example and is not intended to limit the scope of the invention. The above embodiment can be implemented in various other forms, and various omissions, substitutions, combinations, and modifications can be made without departing from the spirit of the invention. Furthermore, the specifications of each configuration, shape, etc. (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate.

For example, the multiple beams may all have the same power, or one or more beams may have a higher power than the other beams. Also, the multiple beams may be classified into multiple groups, with beams within the same group having approximately the same power and beams between groups having different powers. In this case, the power of each beam may be made to differ in stages between the multiple groups. Note that the number of beams included in a group is not limited to multiple, and may be just one.

In addition, the material of the object is not limited to stainless steel.

The object is not limited to plate material, and the welding of the present invention can be applied to various forms of welding, such as lap welding, butt welding, and fillet welding. In other words, the object may be at least two members to be welded that are overlapped, in contact, or adjacent to each other.

When irradiating the laser light, known wobbling, weaving, output modulation, etc. may be performed to adjust the surface area of the molten pool.

The object may also be a metal object with a thin layer of another metal on its surface, such as a plated metal sheet.

100... laser welding apparatus 110... laser apparatus (laser oscillator)
120: Optical head 121: Collimator lens 122: Condenser lens 123: DOE (diffractive optical element, beam shaper)
123a...diffraction grating 130...optical fiber 140...supply mechanism (filler wire supply unit)
141... Delivery device 142... Nozzle A1... First power region A2... Second power region B... Bead C... Irradiation center Df... (filler wire) diameter Dl... (laser light) diameter F... Filler wire Fe... End surface e1... Lower end (first end)
e2: tip (second end)
L...Laser light Lm, Ls...Beam M...Molten pool Pm, Ps...Power S...Supply direction SD...Sweeping direction W...Object Wa...Surface X...Direction Y...Direction Z...Direction

Claims (14)

1. A laser welding method for supplying a filler wire onto a surface of an object, and irradiating the surface with a laser beam in a sweeping direction relative to the object, thereby melting the filler wire and welding the object, comprising:
a width ratio, which is a ratio of a width of the filler wire in a direction perpendicular to the sweep direction of the laser light on the surface to a diameter of the filler wire, is 0.8 or more;
the laser beam has a second power region and an annular first power region surrounding the second power region,
a power ratio that is a ratio of the power of the laser light in the second power region to the power of the laser light in the first power region is 3/7 or more and 7/3 or less . the surface is planar;
The laser welding method of claim 1 , wherein substantially the entire area of the first power region and the second power region is irradiated onto the planar surface. The laser welding method according to claim 1 or 2 , wherein the width ratio is 4 or less. The laser welding method according to claim 1 , wherein the width ratio is 1.5 or more and 3.6 or less. The laser welding method according to any one of claims 1 to 4, wherein the filler wire is arranged at a position where the laser light forming the first power region is irradiated, and at a position different from a position where the laser light forming the second power region is irradiated. The laser welding method of claim 1 , wherein the first power region includes a plurality of beams of the laser light. The laser welding method of claim 6 , wherein the plurality of beams are arranged in a circular ring shape. The laser welding method of claim 6 , wherein the plurality of beams are arranged in a square-shaped ring. the laser light includes a plurality of beams;
The laser welding method according to any one of claims 1 to 8 , wherein the plurality of beams are formed by a beam shaper. The laser welding method of claim 9 , wherein the beam shaper is a diffractive optical element. The filler wire is positioned in contact with a molten pool formed on the surface;
a first end portion of the end face of the filler wire that is in contact with the molten pool and that is close to the surface is spaced apart from an irradiation center of the laser light on the surface in a first direction;
The laser welding method according to any one of claims 1 to 10 , wherein a second end of the molten pool in the first direction is located farther from the irradiation center in the first direction than the first end. The laser welding method of claim 11 , wherein the first direction is the sweep direction. 13. The laser welding method of claim 11 or 12 , wherein the laser light and the filler wire are swept in the first direction relative to the surface. an optical head that irradiates a laser beam onto a surface of an object;
a filler wire supply section that supplies a filler wire onto the surface;
a laser welding apparatus for irradiating the surface with the laser light in a sweeping direction relative to the object, thereby melting the filler wire and welding the object,
a width ratio, which is a ratio of a width of the filler wire in a direction perpendicular to the sweep direction of the laser light on the surface to a diameter of the filler wire, is 0.8 or more;
the laser beam has a second power region and an annular first power region surrounding the second power region,
A laser welding device , wherein a power ratio, which is a ratio of the power of the laser light in the second power region to the power of the laser light in the first power region, is greater than or equal to 3/7 and less than or equal to 7/3 .

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