Welding method and welding apparatus

Abstract

To provide a new welding method and a new welding apparatus that can make areas of a weld part smaller while suppressing sputter for instance, which can make a diameter of a beam smaller in other words.SOLUTION: In the welding method, a portion irradiated with a laser beam in a work-piece is melted to perform welding by irradiating a surface of the work-piece with the laser beam that moves in a sweeping direction relatively with respect to the work-piece. The lase beam includes a plurality of beams, and the plurality of beams include at least one main beam and at least one sub beam that is smaller in power than the main beam. On the surface are formed a main power region including the at least one main beam and a sub power region including the at least one sub beam, where a shortest distance between centers of the plurality of beams made adjacent to each other on the surface is 75[μm] or less.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a welding method and a welding apparatus.

Background Art

[0002] Laser welding is known as one of methods for welding a workpiece made of a metal material. Laser welding is a welding method in which a laser beam is irradiated onto a portion to be welded of a workpiece, and the portion is melted by energy of the laser beam. A pool of molten metal material called a molten pool is formed in a portion irradiated with the laser beam, and welding is performed by subsequent solidification of the molten pool.

[0003] Further, when irradiating a workpiece with a laser beam, a profile of the laser beam may be shaped depending on the purpose of the irradiation. For example, when a laser beam is used for cutting a workpiece, a technique for shaping the profile of the laser beam is known (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of Invention

Problem to be Solved by the Invention

[0005] Incidentally, it is known that spatter, or flying debris, is generated from the molten pool during welding. This spatter is scattered molten metal, and reducing its generation is important in preventing processing defects. Since spatter is scattered molten metal, its generation also means that the amount of metal material at the weld site is reduced. In other words, if a lot of spatter is generated, the amount of metal material at the weld site will be insufficient, which can lead to problems such as insufficient strength. Furthermore, the generated spatter adheres to the area around the weld site, and if it later peels off and adheres to electrical circuits, it can cause malfunctions in the electrical circuits. Therefore, welding components for electrical circuits can be difficult in some cases.

[0006] Furthermore, in this type of welding, when the workpiece is smaller or thinner, it becomes necessary to reduce the area of ​​the weld, that is, to reduce the diameter of the beam.

[0007] Therefore, one of the objectives of the present invention is to obtain a novel welding method and welding apparatus that can reduce the area of ​​the weld, that is, reduce the diameter of the beam, while suppressing spatter. [Means for solving the problem]

[0008] In the welding method of the present invention, for example, welding is performed by irradiating the surface of a workpiece with laser light that moves in a sweeping direction relative to the workpiece, thereby melting the portion of the workpiece irradiated with the laser light, wherein the laser light includes a plurality of beams, the plurality of beams including at least one main beam and at least one sub-beam having less power than the main beam, a main power region including the at least one main beam and a sub-power region including the at least one sub-beam are formed on the surface, and the minimum distance between the centers of adjacent plurality of beams on the surface is 75 [μm] or less.

[0009] In the welding method described above, the laser light may be a single-mode laser light.

[0010] In the welding method described above, the diameter of the beam on the surface may be 100 [μm] or less.

[0011] In the welding method described above, the distance between the centers of the plurality of beams that are furthest apart in a direction perpendicular to the sweeping direction on the surface may be 300 [μm] or less.

[0012] In the welding method described above, the ratio of the power in the main power region to the power in the sub-power region may be within the range of 72:1 to 1:50.

[0013] In the welding method described above, at least one sub-beam may be positioned in front of the at least one main beam in the sweeping direction.

[0014] In the welding method described above, at least one sub-beam may be positioned behind the at least one main beam in the sweeping direction.

[0015] In the welding method described above, the at least one sub-beam may be positioned offset from the at least one main beam in a direction intersecting the sweep direction.

[0016] In the welding method described above, a plurality of sub-beams may be arranged around the at least one main beam, with the at least one sub-beam being the sub-beam.

[0017] In the welding method described above, the plurality of sub-beams may be arranged in an arc shape.

[0018] In the welding method described above, the plurality of sub-beams may be arranged in a rectangular shape.

[0019] In the welding method described above, the main power region and the sub power region may be arranged such that a molten pool formed by the at least one main beam included in the main power region and a molten pool formed by the at least one sub beam included in the sub power region partially overlap each other.

[0020] In the welding method described above, the wavelength of the laser beam of the at least one main beam included in the main power region and the wavelength of the laser beam of the at least one sub beam included in the sub power region may be the same.

[0021] In the welding method described above, the wavelength of the laser beam of the at least one sub beam included in the sub power region may be a wavelength having a higher absorptivity for the processing target than the wavelength of the laser beam of the at least one main beam included in the main power region.

[0022] In the welding method described above, the laser beam of the at least one main beam included in the main power region and the laser beam of the at least one sub beam included in the sub power region may be emitted from the same oscillator.

[0023] In the welding method described above, the laser beam of the at least one main beam included in the main power region and the laser beam of the at least one sub beam included in the sub power region may be emitted from different laser oscillators.

[0024] In the welding method described above, the M of the laser beam 2 beam quality may be 1.3 or less.

[0025] In the welding method described above, the distance between centers of the plurality of beams may be 5 µm or more.

[0026] In the welding method described above, the arrangement of the plurality of beams may be formed by a beam shaper.

[0027] In the welding method described above, the beam shaper may be a diffractive optical element.

[0028] In the welding method described above, the workpiece may consist of at least two overlapping members.

[0029] In the welding method described above, the diameter of the main beam and the diameter of the sub-beam may be the same.

[0030] The welding apparatus of the present invention comprises, for example, a laser oscillator and an optical head that performs welding by irradiating the surface of a workpiece with laser light including a plurality of beams formed from light emitted from the laser oscillator, thereby melting the portion of the workpiece irradiated with the laser light. The workpiece and at least a part of the optical head are configured to move relative to each other so that the laser light moves in a sweeping direction relative to the workpiece. The plurality of beams include at least one main beam and at least one sub-beam having less power than the main beam. A main power region including the at least one main beam and a sub-power region including the at least one sub-beam are formed on the surface, and the minimum distance between the centers of adjacent plurality of beams on the surface is 75 [μm] or less. [Effects of the Invention]

[0031] According to the present invention, it is possible to suppress the generation of spatter and to reduce the area of ​​the weld, that is, to reduce the diameter of the beam. [Brief explanation of the drawing]

[0032] [Figure 1] Figure 1 is an illustrative schematic diagram of a laser welding apparatus according to the first embodiment. [Figure 2] Figure 2 is an explanatory diagram illustrating the concept of the principle of the diffractive optical element included in the laser welding apparatus of the first embodiment. [Figure 3]Figure 3 is a schematic diagram showing an example of a beam (spot) of laser light emitted from the laser welding apparatus of the first embodiment on the surface of the workpiece. [Figure 4] Figure 4 is a schematic diagram showing an example of a beam (spot) of laser light emitted from the laser welding apparatus of the first embodiment on the surface of the workpiece. [Figure 5] Figure 5 is an explanatory diagram showing an example of the intensity distribution of each beam in a direction perpendicular to the sweep direction on the surface of the workpiece irradiated by the laser welding apparatus of the first embodiment. [Figure 6] Figure 6 is an explanatory diagram showing another example of the intensity distribution of each beam in a direction perpendicular to the sweep direction on the surface of the workpiece irradiated by the laser welding apparatus of the first embodiment. [Figure 7] Figure 7 is a graph showing the ratio of the number of spatters in welding using the laser welding apparatus of the first embodiment to the number of spatters in welding using a laser welding apparatus without a diffractive optical element, as a reference example. [Figure 8] Figure 8 is an explanatory diagram showing the surface of the welding area by the laser welding apparatus of the first embodiment, and the change in surface height in the sweeping direction. [Figure 9] Figure 9 is an illustrative schematic diagram of a laser welding apparatus according to the second embodiment. [Figure 10] Figure 10 is an illustrative schematic diagram of a laser welding apparatus according to the third embodiment. [Figure 11] Figure 11 is a schematic diagram showing an example of a beam (spot) of laser light emitted from the laser welding apparatus of the first embodiment on the surface of the workpiece. [Figure 12] Figure 12 is a schematic diagram showing an example of a beam (spot) of laser light emitted from the laser welding apparatus of the first embodiment on the surface of the workpiece. [Figure 13] Figure 13 is a schematic diagram showing an example of a beam (spot) of laser light emitted from the laser welding apparatus of the first embodiment on the surface of the workpiece. [Figure 14]Figure 14 is a schematic diagram showing an example of a beam (spot) of laser light emitted from the laser welding apparatus of the first embodiment on the surface of the workpiece. [Figure 15] Figure 15 is a diagram showing the arrangement of numbers indicating the position of each beam, illustrating an example of a beam (spot) of laser light emitted from a laser welding apparatus of the first embodiment on the surface of a workpiece using a matrix with numbered cells. [Figure 16] Figure 16 is an explanatory diagram showing the beam arrangement and the number of each beam, as in the example shown in Figure 3. [Modes for carrying out the invention]

[0033] Illustrative embodiments of the present invention are disclosed below. The configurations of the embodiments shown below, as well as the actions and results (effects) brought about by such configurations, are examples only. The present invention can also be realized by 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 derived effects) that can be obtained by the configuration.

[0034] The embodiments shown below have similar configurations. Therefore, the configurations of each embodiment provide similar functions and effects based on those similar configurations. In the following, similar components are given the same reference numerals, and redundant explanations may be omitted.

[0035] Furthermore, in each figure, direction X is represented by arrow X, direction Y by arrow Y, and direction Z by arrow Z. Directions X, Y, and Z intersect and are also orthogonal to each other. The Z direction is the normal direction to the surface Wa (machined surface) of the workpiece W.

[0036] [First Embodiment] [Configuration of a laser welding system] Figure 1 shows a schematic configuration of a laser welding apparatus 100 according to the first embodiment. The laser welding apparatus 100 comprises a laser device 110, an optical head 120, and an optical fiber 130 connecting the laser device 110 and the optical head 120. The laser welding apparatus 100 is an example of a welding apparatus.

[0037] The workpiece W of the laser welding apparatus 100 can be made of, for example, iron-based metal materials, aluminum-based metal materials, copper-based metal materials, etc. The workpiece W may have a plate-like shape, and its thickness may be, for example, 1 mm or more and 10 mm or less, but is not limited to this. Furthermore, the workpiece W may consist of multiple overlapping components. The number of components and the thickness of each component can be varied.

[0038] The laser device 110 is equipped with a laser oscillator and, for example, is configured to output single-mode laser light with a power of several kW. Alternatively, the laser device 110 may be configured to include multiple semiconductor laser elements internally, and to output multi-mode laser light with a power of several kW as the combined output of these multiple semiconductor laser elements. Furthermore, the laser device 110 may be equipped with various laser light sources such as fiber lasers, YAG lasers, and disk lasers.

[0039] 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 single-mode laser light, the optical fiber 130 is configured to propagate the single-mode laser light. In this case, the M of the single-mode laser light 2 The beam quality is set to 1.3 or lower. 2 Beam quality can also be referred to as the M2 factor.

[0040] The optical head 120 is an optical device for irradiating the laser light input from the laser device 110 toward the workpiece W. The optical head 120 includes a collimating lens 121, a focusing lens 122, and a DOE 123 (diffractive optical element). The collimating lens 121, the focusing lens 122, and the DOE 123 may also be referred to as optical components.

[0041] The optical head 120 is configured to change its relative position to the workpiece W in order to sweep the laser beam L while irradiating it onto the workpiece W. The relative movement between the optical head 120 and the workpiece W can be achieved by moving the optical head 120, moving the workpiece W, or moving both the optical head 120 and the workpiece W.

[0042] The collimating lens 121 collimates the input laser beam. The collimated laser beam becomes parallel light. The focusing lens 122 then focuses the parallel laser beam and irradiates the workpiece W with the laser beam L (output light).

[0043] The DOE123 is positioned between the collimating lens 121 and the focusing lens 122 to shape the laser beam (hereinafter referred to as the beam shape). As conceptually illustrated in Figure 2, the DOE123 has a configuration in which, for example, multiple diffraction gratings 123a with different periods are superimposed. The DOE123 can shape the beam by bending or superimposing parallel light in the direction influenced by each diffraction grating 123a. The DOE123 may also be referred to as a beam shaper.

[0044] [Beam (spot) shape] The DOE123 splits the laser light input from the collimating lens 121 into multiple beams. Figures 3 and 4 show examples of laser beams (spots) formed on the surface Wa of the workpiece W, respectively. In Figures 3 and 4, for simplicity, the main beam B1 is shown as a solid line and the secondary beam B2 is shown as a dashed line. The arrows SD in Figures 3 and 4 indicate the sweeping direction of the beam on the surface Wa of the workpiece W. As illustrated in Figures 3 and 4, the optical head 120 can output laser light containing multiple beams in various arrangements by changing the DOE123.

[0045] DOE123 splits a laser beam into multiple beams. These multiple beams include at least one main beam B1 and at least one secondary beam B2. The secondary beam B2 is a beam with less power than the main beam B1. For example, the power ratio of the main beam B1 to the secondary beam B2 is set to 2:1, but is not limited to this.

[0046] Furthermore, the DOE123 splits the laser beam so that at least one main beam B1 spot and at least one sub-beam B2 spot are formed on the surface Wa. In the example in Figure 3, the beam shaping by the DOE123 forms one main beam B1 spot and multiple sub-beam B2 spots arranged in a square (rectangular) shape around the main beam B1 spot on the surface Wa. Also, in the example in Figure 3, the multiple beams are arranged in a 3x3 square matrix, and the spacing between beams in the row direction (Y direction) and the spacing between beams in the column direction (X direction, sweep direction SD) are all set to be the same. Of the nine beams, the central beam is the main beam B1, and the eight beams surrounding this single main beam B1 are the sub-beams B2.

[0047] In the example shown in Figure 4, beam shaping by DOE123 forms multiple spots of main beam B1 and multiple spots of sub-beam B2 arranged in a square (rectangular) pattern around the spots of the main beam B1 on the surface Wa. In the example shown in Figure 4, the multiple beams are arranged in a 4x4 square matrix, and the spacing between beams in the row direction (Y direction) and the spacing between beams in the column direction (X direction, sweep direction SD) are all set to be the same. Of the 16 beams, the four central beams are main beam B1, and the 12 beams surrounding these four main beam B1 are sub-beam B2. The region irradiated by the main beam B1 is an example of the main power region, and the region irradiated by the sub-beam B2 is an example of the sub-power region.

[0048] Furthermore, experimental research by the inventors revealed the optimal power ratio range for suppressing sputtering depending on the material being processed: a main power region containing at least one main beam and a sub-power region containing at least one sub-beam. For example, for iron-based metal materials such as carbon steel, stainless steel, or iron alloys, a power ratio of 10:1 to 1:20 between the main power region containing at least one main beam and the sub-power region containing at least one sub-beam is preferable. For copper-based metal materials such as pure copper or copper alloys, a power ratio of 10:1 to 1:1 between the main power region containing at least one main beam and the sub-power region containing at least one sub-beam is preferable. For aluminum-based metal materials such as pure aluminum or aluminum alloys, a power ratio of 10:1 to 1:1 between the main power region containing at least one main beam and the sub-power region containing at least one sub-beam is preferable.

[0049] Furthermore, as shown in Figure 3, the DOE123 shapes the beam such that at least a portion of the spot of any of the sub-beams B2 on the surface Wa is located in front of the spot of the main beam B1 in the sweep direction SD. Specifically, it is sufficient that at least a portion of any of the sub-beams B2 is located in a region A in the sweep direction SD that is forward of a virtual straight line VL passing through the front end B1f of the main beam B1 and perpendicular to the sweep direction SD. Alternatively, the spot of any of the sub-beams B2 may be located behind the spot of the main beam B1. In this case, it is sufficient that at least a portion of any of the sub-beams B2 is located in a region (not shown) in the sweep direction SD that is backward of a virtual straight line (not shown) passing through the rear end (not shown) of the main beam B1 and perpendicular to the sweep direction SD.

[0050] Figures 5 and 6 show examples of the intensity distribution of each beam on the surface Wa of the workpiece W, in a direction perpendicular to the sweep direction SD. Both Figures 5 and 6 show the distribution at position x1 in Figure 3. Position x1 is the position in the X direction of the center of the main beam B1.

[0051] As shown in Figures 3-6, in this embodiment, in the Y direction, i.e., the width direction when the sweep direction SD is the X direction, the main beam B1 is located near the center of the irradiation area of ​​beams B1 and B2, and the sub-beam B2 is located further away from the center. The width of the laser beam L is defined as the distance w between the centers of the two beams that are furthest apart in the width direction. In Figure 5, the width of the laser beam L is the distance w1 between the centers of the beams (sub-beam B2) located at both ends in the width direction, and in Figure 6, the width of the laser beam L is the distance w2 between the centers of the beams (sub-beam B2) located at both ends in the width direction.

[0052] Experimental studies by the inventors revealed that the width of the laser beam L is preferably between 50 [μm] and 300 [μm], and more preferably between 50 [μm] and 200 [μm]. Furthermore, the diameter bd of each beam is preferably 100 [μm] or less, and more preferably 25 [μm] or less. Additionally, the minimum distance bi (see Figures 3 and 4) between multiple adjacent beams is preferably 75 [μm] or less, and more preferably 50 [μm] or less.

[0053] Furthermore, multiple beams may be integrated. In this case, the main beam B1 and the secondary beam B2 have a power distribution in the radial direction of their beam cross-section, for example, a Gaussian shape. In this case, the beam diameter of each beam includes the peak of that beam, and the peak intensity is 1 / e 2 This can be defined as the diameter of the region of intensity above. For non-circular beams, in this specification, 1 / e of the peak intensity is defined as the longer axis (e.g., major axis) passing near the center of the beam or the shorter axis (e.g., minor axis) perpendicular to the longer axis (major axis). 2 The length of the region where the intensity is above is defined as the beam diameter. Furthermore, the power of each beam includes the peak intensity of that beam, and is 1 / e 2 This represents power within the intensity range described above.

[0054] Through appropriate design or adjustment of the laser device 110, optical fiber 130, collimating lens 121, focusing lens 122, and DOE 123, the laser welding apparatus 100 can output laser light L including the main beam B1 and sub-beam B2 as described above.

[0055] [Welding Method] In welding using the laser welding apparatus 100, first, the workpiece W is set in the area to be irradiated by the laser beam L. Then, with the laser beam L, including the main beam B1 and sub-beam B2 divided by the DOE 123, irradiating the workpiece W, the laser beam L and the workpiece W move relative to each other. As a result, the laser beam L moves (sweeps) across the surface Wa in the sweep direction SD while being irradiated onto the surface Wa. The part irradiated by the laser beam L melts, and then solidifies as the temperature decreases, thereby welding the workpiece W. In this embodiment, for example, the sweep direction SD is the X direction, but the sweep direction SD is not limited to the X direction and only needs to intersect with the Z direction.

[0056] Experimental studies by the inventors have confirmed that sputtering can be suppressed by positioning at least a portion of the sub-beam B2 ahead of the main beam B1 in the sweep direction SD in the laser beam L. This is presumed to be because, for example, preheating the workpiece W with the sub-beam B2 before the main beam B1 arrives stabilizes the molten pool of the workpiece W formed by the sub-beam B2 and the main beam B1.

[0057] Furthermore, from the viewpoint of performing sufficient preheating over a relatively wide area, it was found that the minimum distance between multiple beams is preferably 5 [μm] or more, and more preferably 10 [μm] or more.

[0058] [Experimental Results] Figure 7 is a graph showing the ratio of the number of spatters in welding using the laser welding apparatus 100 of this embodiment to the number of spatters in welding using a laser welding apparatus without a DOE of 123, as a reference example.

[0059] The inventors conducted an experiment using a laser welding apparatus 100 to perform laser welding on a workpiece W by irradiating it with laser light L having the beam shapes shown in Figures 3 and 4, and measuring the number of sputters. As a reference example, they also conducted an experiment to measure the number of sputters under the same conditions when there was no DOE123 and the laser light irradiated onto the workpiece W was a single beam (spot). The graph in Figure 7 shows the ratio of the number of sputters in each case of Figures 3 and 4 to the number of sputters in the reference example case.

[0060] In this experiment, the number of spatter particles larger than 50 μm generated during welding was measured for cases where the relative movement speed between the surface Wa and the laser beam L (hereinafter referred to as the sweep speed) was 30 [m / min], 20 [m / min], 10 [m / min], 5 [m / min], 2 [m / min], 1 [m / min], and 0.5 [m / min].

[0061] In this experiment, the wavelength of the laser light output from the laser device 110 was set to 1070 nm. In the case of the beam shape shown in Figure 3 (circle in Figure 7), the beam shape shown in Figure 4 (square in Figure 7), and the reference example (triangle in Figure 7), although the number and arrangement of beams differed, the total power of the laser light L was set to 1.5 kW in all cases.

[0062] In this experiment, for the beam shapes shown in Figure 3 and Figure 4, the width w(w1,w2) of the laser beam L was set to 100 [μm], and the diameter bd of the spot of each beam was set to 21 [μm]. Furthermore, the distance between the centers of adjacent beams in the X and Y directions was set to 33 [μm] for the beam shape shown in Figure 3, and to 25 [μm] for the beam shape shown in Figure 4. Also, M 2 The beam quality was set to 1.06.

[0063] Furthermore, a single sheet of stainless steel (SUS304) with a thickness of 10 mm was used as the material to be processed W. It can be estimated that when the materials to be processed W are stacked in the thickness direction (Z direction) and are in close contact with each other, the aspect ratio is almost independent of the thickness and number of materials to be processed W. In other words, it can be estimated that the same results will be obtained even when the materials to be processed W are multiple sheets of the same material stacked in close contact with each other in the thickness direction, as in this experiment where the material to be processed W is a single sheet.

[0064] As shown in Figure 7, the ratio was 1 or less for each condition in the experiment. In other words, in all cases where welding was performed with the beam shapes in Figure 3 and Figure 4, the number of spatters was less than or equal to the reference example.

[0065] Furthermore, this experiment confirmed that humping is reduced. Humping is a phenomenon that occurs during welding when the balance of surface tension of the molten metal is disrupted, causing the flow velocity of the molten metal in the backward direction of welding to become intermittent, resulting in the periodic occurrence of peaks and valleys in the molten metal. Figure 8 shows the surface Wa of the welded area Wm and the change in the height of the surface Wa in the sweep direction for the beam shape shown in Figure 4. The upper part of Figure 8 is a photograph of the surface Wa of the welded area Wm, and the lower part shows the change in the position of the surface Wa of the welded area Wm in the Z direction at position y1 in the upper photograph with a solid line, and the change in the position of the surface Wa of the welded area Wm in the Z direction in the reference example without DOE123 with a dashed line. As shown in the lower part of Figure 8, the maximum difference in the position of the surface Wa in the Z direction at position y1 in this embodiment is δ1, and the maximum difference in the reference example is δ0, so it can be seen that δ1 < δ0. Thus, according to this embodiment, humping can be reduced compared to the reference example without DOE123.

[0066] As described above, in this embodiment, the laser light L output by the laser welding apparatus 100 includes a plurality of beams, each of which includes at least one main beam B1 and at least one sub-beam B2 having less power than the main beam B1, and a main power region including at least one main beam B1 and a sub-power region including at least one sub-beam B2 are formed on the surface Wa. The minimum distance between the centers of adjacent plurality of beams on the surface Wa is set to 75 [μm] or less.

[0067] Such welding methods and welding apparatus make it possible to reduce the width of the welded area Wm while suppressing the generation of spatter.

[0068] Furthermore, experimental studies by the inventors revealed that the diameter of each beam (main beam B1, sub-beam B2) is preferably 100 [μm] or less on the surface Wa, and the distance between the centers of the most widely spaced beams in the direction perpendicular to the sweep direction SD is preferably 300 [μm] or less on the surface Wa.

[0069] Such welding methods and welding apparatus make it possible to narrow the width of the welded area Wm while suppressing the generation of spatter, for example.

[0070] Also, the M of the laser light L 2 The beam quality is preferably 1.3 or less. This allows for a narrower width of the weld area Wm while suppressing spatter generation.

[0071] Furthermore, experimental studies by the inventors have shown that, as shown in Figures 3 and 4, in each of the following cases, the width of the welded area Wm can be made narrower while suppressing spatter generation: when at least one sub-beam B2 is positioned in front of at least one main beam B1 in the sweep direction SD; when at least one sub-beam B2 is positioned behind at least one main beam B1 in the sweep direction SD; when at least one sub-beam B2 is positioned offset in a direction intersecting the sweep direction SD with respect to at least one main beam B1; when multiple sub-beams B2 are positioned around at least one main beam B1; and when multiple sub-beams are arranged in a square shape.

[0072] Furthermore, experimental research by the inventors revealed that when the ratio of power in the main power region to the power in the sub-power region is within the range of 72:1 to 1:50, the width of the welded area Wm can be narrowed while suppressing spatter generation.

[0073] Furthermore, in this embodiment, the main power region and the sub-power region may be arranged such that the molten pool formed by at least one main beam B1 included in the main power region and the molten pool formed by at least one sub-beam B2 included in the sub-power region partially overlap. In this case, at least a portion of the energy of the main beam B1 is irradiated onto the molten pool formed by the sub-beam B2 of the workpiece W. As a result, the molten pool formed by the main beam B1 becomes relatively stable, and the effect of suppressing sputter generation is obtained.

[0074] Furthermore, in this embodiment, the main beam B1 may have a power density capable of generating keyholes in the workpiece W. In this case, the penetration depth in welding can be increased.

[0075] Furthermore, in this embodiment, the wavelength of the laser light of at least one main beam included in the main power region and the wavelength of the laser light of at least one sub-beam included in the sub-power region may be the same. In this case, the main beam and sub-beam can be generated from a single laser beam.

[0076] Furthermore, in this embodiment, the wavelength of the laser light of at least one sub-beam included in the sub-power region may be a wavelength that has a higher absorption rate for the workpiece than the wavelength of the laser light of at least one main beam included in the main power region. In this case, even if the power or power density of the sub-beam is relatively low, the energy delivered to the workpiece can be made relatively large, and the effects of irradiating with a sub-beam can be enjoyed.

[0077] Furthermore, in this embodiment, the laser light of at least one main beam included in the main power region and the laser light of at least one sub-beam included in the sub-power region may be emitted from the same oscillator. In this case, the main beam and sub-beam can be generated from laser light emitted from a single oscillator.

[0078] Furthermore, in this embodiment, the laser light of at least one main beam included in the main power region and the laser light of at least one sub-beam included in the sub-power region may be emitted from different laser oscillators. In this case, it becomes easier to independently set the characteristics of the main beam and the sub-beam.

[0079] [Second Embodiment] Figure 9 shows a schematic configuration of the laser welding apparatus of the second embodiment. The laser welding apparatus 200 irradiates the workpiece W1 with laser light L to weld the workpiece W1. The workpiece W1 is composed of two plate-shaped metal members W11 and W12 stacked on top of each other. The laser welding apparatus 200 achieves welding by the same operating principle as the laser welding apparatus 100. Therefore, only the configuration of the laser welding apparatus 200 will be described below.

[0080] The laser welding apparatus 200 comprises a laser device 210, an optical head 220, and an optical fiber 230.

[0081] The laser device 210 is equipped with a laser oscillator and is configured similarly to the laser device 110, and is configured to output laser light with a power of, for example, several kW. The optical fiber 230 guides the laser light output from the laser device 210 and inputs it to the optical head 220.

[0082] The optical head 220, like the optical head 120, is an optical device for irradiating the laser light input from the laser device 210 toward the workpiece W1. The optical head 220 is equipped with a collimating lens 221 and a focusing lens 222.

[0083] Furthermore, the optical head 220 has a galvanoscanner positioned between the focusing lens 222 and the workpiece W1. The galvanoscanner is a device that can move the irradiation position of the laser beam L and sweep the laser beam L without moving the optical head 220 by controlling the angles of two mirrors 224a and 224b. The laser welding apparatus 200 is equipped with a mirror 226 to guide the laser beam L emitted from the focusing lens 222 to the galvanoscanner. In addition, the angles of the mirrors 224a and 224b of the galvanoscanner are changed by motors 225a and 225b, respectively.

[0084] The optical head 220 includes a beam shaper, the DOE 223, positioned between the collimating lens 221 and the focusing lens 222. Similar to the DOE 123, the DOE 223 splits the laser light input from the collimating lens 221, generating a main beam and at least one sub-beam. At least a portion of the sub-beam is located forward of the main beam in the sweep direction. In this embodiment as well, the power ratio can be set in the same manner as in the first embodiment.

[0085] [Third Embodiment] Figure 10 shows a schematic configuration of a laser welding apparatus according to the third embodiment. The laser welding apparatus 300 irradiates the workpiece W2 with laser light L to weld the workpiece W2. The workpiece W2 is composed of two plate-shaped metal members W21 and W22 placed adjacent to each other so as to butt together. The laser welding apparatus 300 is equipped with a laser oscillator and achieves welding by the same operating principle as the laser welding apparatuses 100 and 200. The configuration of elements other than the optical head 320 (laser device 310 and optical fiber 330) is the same as the corresponding elements of the laser welding apparatuses 100 and 200. Therefore, only the configuration of the optical head 320 will be described below.

[0086] The optical head 320, like the optical heads 120 and 220, is an optical device for irradiating the laser light input from the laser device 310 toward the workpiece W2. The optical head 320 is equipped with a collimating lens 321 and a focusing lens 322.

[0087] Furthermore, the optical head 320 has a galvanoscanner positioned between the collimating lens 321 and the focusing lens 322. The mirrors 324a and 324b of the galvanoscanner have their angles changed by motors 325a and 325b, respectively. The optical head 320 has the galvanoscanner in a different position than the optical head 220. However, similar to the optical head 220, by controlling the angles of the two mirrors 324a and 324b, the irradiation position of the laser beam L can be moved and the laser beam L can be swept without moving the optical head 320.

[0088] The optical head 320 includes a beam shaper, the DOE 323, positioned between the collimating lens 321 and the focusing lens 322. Similar to the DOEs 123 and 223, the DOE 323 splits the laser light input from the collimating lens 321, generating a main beam and at least one sub-beam. At least a portion of the sub-beam is located forward of the main beam in the sweep direction. In this embodiment as well, the power ratio can be set in the same manner as in the first embodiment.

[0089] Figures 11-14 also show other examples of the arrangement of multiple laser beams L on the surface Wa of the workpiece W.

[0090] In the example shown in Figure 11, the laser beam L has one main beam B1 and one sub-beam B2, with the sub-beam B2 positioned ahead of the main beam B1 in the sweep direction SD (X direction).

[0091] In the example shown in Figure 12, the laser beam L has one main beam B1 located in the center and 16 sub-beams B2 arranged in a ring around it.

[0092] In the example shown in Figure 13, the laser beam L has 25 beams arranged in a 5x5 square matrix, as well as one sub-beam B2 located in the center, nine main beams B1 arranged in a 3x3 square (quadrilateral) shape around it, and sixteen sub-beams B2 arranged in a square (quadrilateral) shape around those. In this example as well, the spacing between beams in the row direction (Y direction) and the spacing between beams in the column direction (X direction, sweep direction SD) are all set to be the same.

[0093] In the example shown in Figure 14, the laser beam L has multiple beams extending in a zigzag pattern along the Y direction. In other words, each beam is located either at the front or rear of the X direction, and the position of the beam alternates between the front and rear as it moves toward the Y direction. One main beam B1 is located at the rear of the midpoint in the Y direction. Multiple sub-beams B2 are arranged in the Y direction and in the opposite direction to the main beam B1. The spacing between adjacent beams is approximately the same.

[0094] In addition to the examples described above, various other beam arrangement patterns are possible. To illustrate the variations in beam arrangement, we introduce a 7x7 matrix with numbered cells from 1 to 49, as shown in Figure 15. Each cell indicates the position of a beam. In the matrix illustrated in Figure 15, the cell numbers are set so that the rows in the opposite direction of the X direction (rear in the X direction) are larger, and the columns in the Y direction (front in the Y direction) are larger.

[0095] Figure 16 shows the arrangement of the main beam B1 and sub-beam B2, the cell numbers where the main beam B1 is located, and the cell numbers where the sub-beam B2 is located, in the pattern shown in Figure 3. As shown in Figure 17, in the pattern shown in Figure 3, the main beam B1 is located at position number 25, and the eight sub-beams B2 are located at positions 17-19, 24, 26, and 31-33. Note that the matrix in Figure 15 shows the relative positions of multiple beams, and the size and spacing of each beam can be changed as appropriate.

[0096] Multiple beams can be arranged in patterns such as [1] to

[22] below, where the numbers indicate the cell positions in the matrix in Figure 15. [1](Figure 11) Main beam B1:25 Subbeam B2:18 [2] Main beam B1:25 Subbeam B2: 18, 32 [3] Main beam B1:25 Sub-beam B2: 17, 19 [4] Main beam B1:25 Sub-beam B2: 17~19 [5] Main beam B1:25 Sub-beam B2: 11, 17, 19 [6] Main beam B1: 24, 25 Subbeam B2: 17, 18 [7] Main beam B1:25 Sub-beam B2: 18, 24, 26, 32 [8] Main beam B1:25 Sub-beam B2: 17, 19, 31, 33 [9](Figure 3) Main beam B1:25 Sub-beam B2: 17~19, 24, 26, 31~33

[10] Main beam B1:25 Sub-beam B2: 1,3,5,7,15,21,29,35,43,45,47,49

[11] (Figure 4) Main beam B1: 24, 25, 31, 32 Sub-beam B2: 16~19, 23, 26, 30, 33, 37~40

[12] Main beam B1:25 Sub-beam B2: 10~12, 16, 20, 23, 27, 30, 34, 38~40

[13] Main beam B1:25 Sub-beam B2: 9~13, 16, 20, 23, 27, 30, 34, 37~41

[14] Main beam B1:25 Sub-beam B2: 9~13, 16~20, 23, 24, 26, 27, 30~34, 37~41

[15] (Figure 12) Main beam B1:25 Sub-beam B2: 3~5, 9, 13, 15, 21, 22, 28, 29, 35, 37, 41, 45~47

[16] Main beam B1:25 Sub-beam B2: 10~12, 16~20, 23, 24, 26, 27, 30~34, 38~40

[17] Main beam B1: 18, 24~26, 32 Sub-beam B2: 10~12, 16, 17, 19, 20, 23, 27, 30, 31, 33, 34, 38~40

[18] Main beam B1: 17~19, 24~26, 31~33 Sub-beam B2: 10~12, 16, 20, 23, 27, 30, 34, 38~40

[19] Main beam B1: 17~19, 24, 26, 31~33 Sub-beam B2: 10~12, 16, 20, 23, 25, 27, 30, 34, 38~40

[20] Main beam B1: 18, 24~26, 32 Sub-beam B2: 9~13,16,17,19,20,23,27,30,31,33,34,37~41 [twenty one] Main beam B1: 17~19, 24~26, 31~33 Sub-beam B2: 9~13, 16, 20, 23, 27, 30, 34, 37~41

[22] (Figure 12) Main beam B1: 17~19, 24, 26, 31~33 Sub-beam B2: 9~13, 16, 20, 23, 25, 27, 30, 34, 37~41

[0097] As shown in Figure 12, the multiple sub-beams B2 may be arranged in a roughly circular or arc shape. In this case, the centers of each sub-beam B2 may be located on the same circumference.

[0098] Although embodiments of the present invention have been illustrated above, these embodiments are merely examples and are not intended to limit the scope of the invention. The above embodiments 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, each configuration, shape, and other specifications (structure, type, orientation, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate.

[0099] For example, in each of the above embodiments, the welding method of the main beam (main power region) may be keyhole welding or heat conduction welding. Keyhole welding, as used here, is a welding method that utilizes a keyhole. On the other hand, heat conduction welding is a welding method that melts the workpiece by utilizing the heat generated when laser light is absorbed on the surface of the workpiece.

[0100] Furthermore, all subbeams may have the same power, or one or some subbeams may have a higher power than the others. Also, multiple subbeams can be classified into multiple groups, with subbeams having approximately the same power within the same group, and subbeams having different powers between groups. In this case, comparing subbeams classified into multiple different groups will result in gradually different power levels. Note that a group may contain more than one subbeam; it may contain just one.

[0101] Furthermore, the material to be processed is not limited to stainless steel.

[0102] Furthermore, the workpiece is not limited to sheet metal, nor is the welding method limited to overlap welding or butt welding. Therefore, the workpiece may consist of at least two members to be welded, which are overlapped, in contact with, or adjacent to each other.

[0103] Furthermore, when sweeping the laser beam over the workpiece, the surface area of ​​the molten pool may be adjusted by sweeping using known methods such as wobbling, weaving, or output modulation.

[0104] Furthermore, the object to be processed may be a metal plated metal sheet, where a thin layer of another metal exists on the surface of the metal. [Industrial applicability]

[0105] This invention can be used in welding methods and welding apparatus. [Explanation of Symbols]

[0106] 100, 200, 300... Laser welding equipment (welding equipment) 110, 210, 310… Laser devices (laser oscillators) 120, 220, 320… Optical heads 121,221,321…Collimating lenses 122,222,322… Focusing lenses 123,223,323…DOE (Diffractive Optical Elements) 123a...Diffraction grating 130, 230, 330… Fiber optics 224a, 224b, 226, 324a, 324b…Mirror 225a, 225b, 325a, 325b… motors A... (the area in front in the sweeping direction) B1...Main beam (beam, main power area) B1f…front end B2... Sub-beam (beam, sub-power region) bd... (beam) diameter bi… (minimum distance between beams) L... Laser light SD…Sweep direction VL…Virtual line W, W1, W2... Processing targets Wa... Surface W11, W12, W21, W22… Metal components Wm...Welding area w, w1, w2... Distance (width) x1,y1…position X…direction Y... Direction Z…direction (normal direction)

Claims

1. A welding method comprising irradiating the surface of a workpiece with laser light that moves in a sweeping direction relative to the workpiece, thereby melting and welding the portion of the workpiece irradiated with the laser light, The laser light includes a plurality of beams, The plurality of beams include at least one main beam having a Gaussian-shaped power distribution and at least one sub-beam having a Gaussian-shaped power distribution and having less power than the main beam. With respect to the at least one main beam, the at least one sub-beam is positioned in front of the sweep direction, A main power region including the at least one main beam and a sub-power region including the at least one sub-beam are formed on the surface. On the aforementioned surface, the minimum distance between the centers of adjacent beams is 5 [μm] or more and less than 75 [μm]. The aforementioned laser light is single-mode laser light, The M of the laser beam ２ The beam quality is 1.3 or less. On the aforementioned surface, the diameter of the beam is 25 [μm] or less. On the aforementioned surface, the distance between the centers of the plurality of beams that are furthest apart in the orthogonal direction perpendicular to the sweeping direction is 50 [μm] or less. The laser light comprises, as a plurality of beams, one main beam and two sub-beams adjacent to the main beam on both sides in a direction orthogonal to the main beam, such that their ends overlap, and the power between the main beam and each of the two sub-beams is not zero. A welding method in which the plurality of beams are arranged in a matrix with the centers of each beam spaced apart in the sweeping direction and the orthogonal direction.

2. The welding method according to claim 1, wherein the ratio of the power in the main power region to the power in the sub-power region is within the range of 72:1 to 1:

50.

3. The welding method according to claim 1 or 2, wherein the at least one sub-beam is positioned behind the at least one main beam in the sweeping direction.

4. The welding method according to any one of claims 1 to 3, wherein the at least one sub-beam is positioned offset from the at least one main beam in a direction intersecting the sweep direction.

5. The welding method according to any one of claims 1 to 4, wherein a plurality of sub-beams are arranged around the at least one main beam, with respect to the at least one sub-beam.

6. The welding method according to any one of claims 1 to 5, wherein the main power region and the sub-power region are arranged such that the molten pool formed by the at least one main beam included in the main power region and the molten pool formed by the at least one sub-beam included in the sub-power region partially overlap.

7. The welding method according to any one of claims 1 to 6, wherein the wavelength of the laser light of at least one main beam included in the main power region and the wavelength of the laser light of at least one sub-beam included in the sub-power region are the same.

8. The welding method according to any one of claims 1 to 6, wherein the wavelength of the laser light of the at least one sub-beam included in the sub-power region is a wavelength that has a higher absorption rate for the workpiece than the wavelength of the laser light of the at least one main beam included in the main power region.

9. The welding method according to any one of claims 1 to 8, wherein the laser light of at least one main beam included in the main power region and the laser light of at least one sub-beam included in the sub-power region are emitted from the same oscillator.

10. The welding method according to any one of claims 1 to 8, wherein the laser light of at least one main beam included in the main power region and the laser light of at least one sub-beam included in the sub-power region are emitted from different laser oscillators.

11. The welding method according to any one of claims 1 to 10, wherein the distance between the centers of the plurality of beams is 5 [μm] or more.

12. The welding method according to any one of claims 1 to 11, wherein the arrangement of the plurality of beams is formed by a beam shaper.

13. The welding method according to claim 12, wherein the beam shaper is a diffractive optical element.

14. The welding method according to any one of claims 1 to 13, wherein the object to be processed is a welding method according to any one of claims 1 to 13, wherein at least two members are stacked on top of each other.

15. The welding method according to any one of claims 1 to 14, wherein the diameter of the main beam and the diameter of the sub-beam are the same.

16. A laser oscillator, An optical head that performs welding by irradiating the surface of a workpiece with laser light containing multiple beams formed from light emitted from the laser oscillator, thereby melting the portion of the workpiece irradiated with the laser light, Equipped with, The workpiece and at least a portion of the optical head are configured to move relative to each other so that the laser beam moves in a sweeping direction relative to the workpiece. The plurality of beams include at least one main beam having a Gaussian-shaped power distribution and at least one sub-beam having a Gaussian-shaped power distribution and having less power than the main beam. With respect to the at least one main beam, the at least one sub-beam is positioned in front of the sweep direction, A main power region including the at least one main beam and a sub-power region including the at least one sub-beam are formed on the surface. On the aforementioned surface, the minimum distance between the centers of adjacent beams is 5 [μm] or more and less than 75 [μm]. The aforementioned laser light is single-mode laser light, The M of the laser beam ２ The beam quality is 1.3 or less. On the aforementioned surface, the diameter of the beam is 25 [μm] or less. On the aforementioned surface, the distance between the centers of the plurality of beams that are furthest apart in the orthogonal direction perpendicular to the sweeping direction is 50 [μm] or less. The laser light comprises, as a plurality of beams, one main beam and two sub-beams adjacent to the main beam on both sides in a direction orthogonal to the main beam, such that their ends overlap, and the power between the main beam and each of the two sub-beams is not zero. A welding apparatus in which the centers of the plurality of beams are arranged in a matrix in the sweeping direction and the orthogonal direction.

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