Welding method and welding equipment

Abstract

This welding method comprises disposing an aluminum-containing workpiece in a region irradiated with laser light, irradiating the workpiece with the laser light, and melting the workpiece at the irradiated portion to perform welding. The laser light is composed of a main beam and a plurality of auxiliary beams, wherein the plurality of auxiliary beams are positioned so as to surround an outer periphery of the main beam. This welding device is provided with a laser device and an optical head for irradiating an aluminum-containing workpiece with laser light outputted from the laser device and melting the workpiece at the irradiated portion to perform welding. The laser light with which the workpiece is irradiated is composed of a main beam and a plurality of auxiliary beams. The plurality of auxiliary beams are positioned so as to surround an outer periphery of the main beam.

Description

[Technical field]

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

[0002] Laser welding is known as one of the techniques for welding workpieces made of metal materials. Laser welding is a welding method in which a laser beam is irradiated onto the part to be welded in the workpiece, and the part is melted by the energy of the laser beam. A pool of molten metal material called a molten pool is formed in the part irradiated with the laser beam, and the molten pool is then solidified to perform welding.

[0003] In addition, when a laser beam is irradiated onto a processing target, the profile of the laser beam may be shaped depending on the purpose. For example, a technique for shaping the profile of a laser beam when the laser beam is used to cut the processing target is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2010-508149 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, aluminum-containing members, for example members made of high-purity aluminum or aluminum alloys, are widely used in vehicle parts and electric / electronic device parts as conductive parts, heat dissipation parts, and weight-reducing components (hereinafter, aluminum-containing members may be referred to as aluminum members). On the other hand, the application of laser welding has been attracting attention in order to realize the miniaturization of parts using aluminum members and the increase in processing speed, but welding defects such as blowholes may occur when aluminum members are joined by general laser welding.

[0006] The present invention has been made in consideration of the above, and an object of the present invention is to provide a welding method and welding apparatus that can suppress the occurrence of welding defects such as blowholes when laser welding workpieces including aluminum. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, a welding method according to one aspect of the present invention includes placing an aluminum-containing workpiece in an area where laser light is irradiated, irradiating the laser light toward the workpiece, and melting and welding the workpiece in the irradiated portion, wherein the laser light is composed of a main beam and multiple sub-beams, and the multiple sub-beams are positioned to surround the outer periphery of the main beam.

[0008] In the welding method according to one aspect of the present invention, a ratio of a power of the main beam to a sum of powers of the plurality of sub-beams may be 0:10 to 4:6.

[0009] In the welding method according to one aspect of the present invention, the sub beams may be positioned to form a substantially ring shape with the main beam at the center.

[0010] In a welding method according to one aspect of the present invention, the laser beam is irradiated toward the object to be processed while the laser beam and the object to be processed are moved relative to each other, and the laser beam is swept over the object to be processed, and at least a portion of the multiple sub-beams may be positioned forward in a sweep direction relative to the main beam.

[0011] In a welding method according to one embodiment of the present invention, the objects to be processed are at least two members to be welded, and when the objects to be processed are positioned in an area to be irradiated with the laser light, the at least two members may be positioned so as to overlap, contact, or be adjacent to each other.

[0012] In the welding method according to the aspect of the present invention, the laser light may be split into the main beam and the plurality of sub beams by a beam shaper, and the beams may be irradiated onto the workpiece.

[0013] In the welding method according to one aspect of the present invention, the beam shaper may be a diffractive optical element.

[0014] In the welding method according to one aspect of the present invention, the workpiece may be pure aluminum, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-silicon alloy, an aluminum-magnesium alloy, an aluminum-magnesium-silicon alloy, an aluminum-zinc-magnesium alloy, or an aluminum-zinc-magnesium-copper alloy.

[0015] A welding method according to one aspect of the present invention irradiates a workpiece containing aluminum with laser light, melting and welding the irradiated portion of the workpiece, wherein the laser light is composed of a main beam and multiple sub-beams, the multiple sub-beams are positioned so as to surround the outer periphery of the main beam, and compared to the case of irradiating a single beam of laser light having a total power of the multiple sub-beams and the main beam, the temperature inside a keyhole formed in the workpiece is suppressed to a level at which no metal vapor of the constituent material of the workpiece is generated or is tolerable, and the melt width is widened.

[0016] A welding apparatus according to one aspect of the present invention includes a laser device and an optical head that irradiates laser light output from the laser device toward a workpiece containing aluminum, thereby melting the irradiated portion of the workpiece to perform welding, and the laser light irradiated to the workpiece is composed of a main beam and a plurality of sub-beams, and the plurality of sub-beams are positioned to surround the outer periphery of the main beam.

[0017] In the welding device according to one aspect of the present invention, a ratio of a power of the main beam to a total power of the plurality of sub-beams may be in a range of 0:10 to 4:6.

[0018] In the welding device according to one aspect of the present invention, the plurality of sub beams may be positioned to form a substantially ring shape with the main beam at the center.

[0019] In a welding device according to one aspect of the present invention, the optical head is configured so that the laser light and the workpiece are movable relative to one another, and the laser light is swept over the workpiece while melting and welding is performed, and at least a portion of the multiple sub-beams may be positioned forward in the sweep direction relative to the main beam.

[0020] In the welding device according to one aspect of the present invention, the workpiece may be configured by overlapping, contacting, or adjacent to at least two members to be welded.

[0021] The welding apparatus according to an aspect of the present invention may further include a beam shaper that splits the laser light into the main beam and the plurality of sub beams.

[0022] In the welding apparatus according to one aspect of the present invention, the beam shaper may be a diffractive optical element. Effect of the Invention

[0023] According to the present invention, it is possible to suppress the occurrence of welding defects such as blowholes when laser welding workpieces containing aluminum. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a laser welding device used in the first embodiment. [Diagram 2] FIG. 2 is a schematic diagram illustrating a diffractive optical element. [Figure 3A] FIG. 3A is a schematic diagram illustrating an example of a beam arrangement. [Figure 3B] FIG. 3B is a schematic diagram illustrating an example of a beam arrangement. [Figure 4]FIG. 4 is a schematic diagram for explaining the arrangement of a plurality of beams of laser light in the embodiment. [Diagram 5] FIG. 5 shows the results when the processing speed and output are changed to lap weld the workpieces (A6061, plate thickness 2 mm each, power ratio of main beam to sub-beam 1:9). [Figure 6A] FIG. 6A is a cross-sectional view in a direction perpendicular to the extending direction of the bead when objects to be processed are lap-welded with plate thicknesses of 2 mm and a power ratio of the main beam to the sub-beam of 1:9. [Figure 6B] FIG. 6B is a cross-sectional view parallel to the bead extension direction and in the plate thickness direction when the objects to be processed are lap-welded with plate thicknesses of 2 mm and a power ratio of the main beam to the sub-beam of 1:9. [Figure 7A] FIG. 7A is a cross-sectional view in a direction perpendicular to the extending direction of the bead when workpieces each having a plate thickness of 2 mm are lap-welded under inappropriate conditions. [Figure 7B] FIG. 7B is a cross-sectional view in the plate thickness direction parallel to the bead extension direction when workpieces each having a plate thickness of 2 mm are lap-welded under inappropriate conditions. [Figure 8] FIG. 8 shows the results when the processing speed and output are changed to lap weld the workpieces (A6061, plate thickness of each 1 mm, power ratio of main beam to sub-beam 1:9). [Figure 9] FIG. 9 shows the results when the processing speed and output are changed to lap weld the workpieces (A6061, plate thickness of each 1 mm, power ratio of main beam to sub-beam 3:7). [Figure 10] FIG. 10 shows the results when the processing speed and output are changed to lap weld the workpieces (A5052, plate thickness of each 2 mm, power ratio of main beam to sub-beam 1:9). [Figure 11] FIG. 11 is a schematic diagram illustrating another example of the beam arrangement. [Figure 12] FIG. 12 is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13A] FIG. 13A is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13B]FIG. 13B is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13C] FIG. 13C is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13D] FIG. 13D is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13E] FIG. 13E is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13F] FIG. 13F is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 13G] FIG. 13G is a schematic diagram illustrating yet another example of the beam arrangement. [Figure 14] FIG. 14 is a schematic diagram showing a schematic configuration of a laser welding device according to the second embodiment. [Figure 15] FIG. 15 is a schematic diagram showing a schematic configuration of a laser welding device according to the third embodiment. [Figure 16] FIG. 16 is a schematic diagram showing a schematic configuration of a laser welding device according to the fourth embodiment. [Figure 17] FIG. 17 is a schematic diagram showing a schematic configuration of a laser welding device according to the fifth embodiment. [Figure 18] FIG. 18 is a schematic diagram showing a schematic configuration of a laser welding device according to the sixth embodiment. [Figure 19A] FIG. 19A is a diagram showing an example of the configuration of an optical fiber. [Figure 19B] FIG. 19B is a diagram showing an example of the configuration of an optical fiber. [Figure 20] FIG. 20 is a diagram showing a schematic relationship between the beam profile of laser light and the state of an object to be processed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiment described below. In addition, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals.

[0026] (Embodiment 1) 1 is a schematic diagram showing a schematic configuration of a laser welding apparatus used in the first embodiment. The laser welding apparatus 100 includes a laser device 110, an optical head 120, and an optical fiber 130 that connects the laser device 110 and the optical head 120. The processing target W is formed by stacking two plate-shaped aluminum members W1 and W2. Examples of the aluminum members W1 and W2 include pure aluminum, Al-Cu alloys such as 2011, 2017, 2024, 2117, and 2219, Al-Mn alloys such as 3003, Al-Si alloys such as 4032 and 4043, Al-Mg alloys such as 5052 and 5056, Al-Mg-Si alloys such as 6061 and 6063, Al-Zn-Mg alloys, and Al-Zn-Mg-Cu alloys such as 7075. The aluminum members W1 and W2 are plate-shaped with a thickness of, for example, about 1 mm to 10 mm. The materials of the aluminum members W1 and W2 may be the same or different from each other.

[0027] The laser device 110 is configured to be able to output laser light with a power of, for example, several kW. For example, the laser device 110 may be configured to include a plurality of semiconductor laser elements therein, and to be able to output multi-mode laser light with a power of several kW as the total output of the plurality of semiconductor laser elements. The laser device 110 may also include various laser light sources such as a fiber laser, a YAG laser, and a disk laser. The optical fiber 130 guides the laser light output from the laser device 110 and inputs it to the optical head 120.

[0028] 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 collimator lens 121 and a condenser lens 122. The collimator lens 121 is an optical system for collimating the input laser light. The condenser lens 122 is an optical system for condensing the collimated laser light and irradiating the workpiece W as the laser light L.

[0029] The optical head 120 is configured to be able to change its relative position with respect to the workpiece W in order to sweep the laser light L while irradiating the laser light L on the workpiece W. Methods for changing the relative position with respect to the workpiece W include moving the optical head 120 itself and moving the workpiece W. That is, the optical head 120 may be configured to be able to sweep the laser light L with respect to a fixed workpiece W. Alternatively, the irradiation position of the laser light L from the optical head 120 may be fixed, and the workpiece W may be held movably with respect to the fixed laser light L.

[0030] The optical head 120 includes a diffractive optical element 123 as an example of a beam shaper, which is disposed between the collimating lens 121 and the condensing lens 122. The diffractive optical element 123 is also called a DOE (Diffractive Optical Element), and is configured by integrating a plurality of diffraction gratings 123a having different periods, as conceptually shown in FIG. 2. The diffractive optical element 123 can shape the beam shape by bending the input laser light in a direction influenced by each diffraction grating or by overlapping the light. In this embodiment, the diffractive optical element 123 is disposed between the collimating lens 121 and the condensing lens 122, but it may be disposed on the optical fiber 130 side of the collimating lens 121 or on the processing object W side of the condensing lens 122.

[0031] The diffractive optical element 123 splits the laser light input from the collimator lens 121 into multiple beams. Specifically, the diffractive optical element 123 splits the laser light into a main beam and multiple sub beams. At this time, the diffractive optical element 123 splits the laser light such that at least some of the multiple sub beams are located forward in the sweep direction relative to the main beam.

[0032] 3A and 3B are schematic diagrams for explaining the arrangement of beams. Note that, FIG. 3A and 3B show the arrangement of multiple beams on the irradiation surface of the laser light L of the processing object W. In the example shown in FIG. 3A, the laser light L includes a main beam B1 and multiple sub-beams B2 split by the diffractive optical element 123. In the example shown in FIG. 3A, the number of sub-beams B2 is eight. The eight sub-beams B2 are positioned so as to surround the outer periphery of the main beam B1. Specifically, the eight sub-beams B2 are positioned so as to form an approximately ring shape with a radius R centered on the main beam B1. Also, as in the laser light L' shown in FIG. 3B, the multiple sub-beams B2 may be continuously overlapped to form a ring shape.

[0033] In the example shown in Fig. 3A, three sub beams B2 are located in front of the main beam B1 in the sweep direction SD. Two sub beams B2 are located on the lateral side of the main beam B1 in a direction perpendicular to the sweep direction SD. Three sub beams B2 are located behind the main beam B1 in the sweep direction SD.

[0034] Furthermore, the main beam B1 and each of the sub beams B2 have, for example, a Gaussian-shaped power distribution in the radial direction of the beam cross section. However, the power distribution of the main beam B1 and the sub beams B2 is not limited to a Gaussian shape. In addition, in FIG. 3A, the diameter of the circle representing the main beam B1 and the sub beams B2 is the beam diameter of each beam. The beam diameter of each beam includes the peak of the beam and is 1 / e of the peak intensity. 2 In the case of a non-circular beam, this specification defines the radius as the radius of the region with an intensity equal to or greater than the peak intensity in the direction perpendicular to the sweep direction SD. 2 The length of the region where the intensity is equal to or greater than this is defined as the beam diameter.

[0035] Here, the power of the main beam B1 is smaller than the sum of the powers of the sub-beams B2, and the powers of the eight sub-beams B2 are equal.

[0036] The ratio between the power of the main beam B1 and the sum of the powers of the eight sub beams B2 is 0:10 to 4:6, preferably 1:9 to 3:7. When the ratio is 1:9, the ratio between the power of the main beam B1 and the power of one sub beam B2 is 1:9 / 8=8:9. When the ratio is 3:7, the ratio between the power of the main beam B1 and the power of one sub beam B2 is 3:7 / 8=21:7. When the ratio between the power of the main beam B1 and the sum of the powers of the eight sub beams B2 is 0:10, the main beam B1 does not exist in Figures 3A and 3B.

[0037] It is preferable that at least the power distribution of the main beam B1 has a somewhat sharp shape. If the power distribution of the main beam B1 has a somewhat sharp shape, the penetration depth when melting the workpiece W can be made deep, so that the welding strength can be ensured and the occurrence of welding defects can be more suitably suppressed. If the beam diameter is used as an index of the sharpness of the main beam B1, the beam diameter R1 of the main beam B1 is preferably 100 μm or more and 500 μm or less, and more preferably 200 μm or more and 400 μm or less. If the main beam B1 has a sharp shape, the power required to achieve the same penetration depth can be reduced and the processing speed can be increased. Therefore, it is possible to reduce the power consumption of the laser welding apparatus 100 and improve the processing efficiency. The power distribution of the sub beam B2 may be as sharp as that of the main beam B1. The beam diameter of the sub beam B2 may also be approximately the same as the beam diameter R1 of the main beam B1. The beam width R2 is 300 μm to 2000 μm, preferably 500 μm to 1200 μm. By setting the beam width R2 in the above range, the surface area of ​​the molten pool can be secured and the surface condition of the bead can be made smooth. Note that the beam width R2 is the width of the sub-beam B2 in the direction perpendicular to the sweep direction SD.

[0038] The beam diameter can be designed by appropriately setting the characteristics of the laser device 110, the optical head 120, and the optical fiber 130 used. For example, the beam diameter can be set by setting the beam diameter of the laser light input from the optical fiber 130 to the optical head 120, or by setting the optical system such as the diffractive optical element 123 and the collimator lenses 121 and 122.

[0039] When welding is performed using the laser welding device 100, first, the workpiece W is placed in an area to be irradiated with the laser light L. Next, while the laser light L, which includes the main beam B1 and eight sub-beams B2 split by the diffractive optical element 123, is irradiated onto the workpiece W, the laser light L and the workpiece W are moved relative to each other to sweep the laser light L, and the workpiece W at the portion irradiated with the laser light L is melted and welded. In the case of FIG. 1, the sweep direction is, for example, the front direction or the depth direction of the drawing. In this way, the workpiece W is welded.

[0040] At this time, in the laser light L, three of the eight sub-beams B2 are positioned forward of the main beam B1 in the sweep direction SD, and the ratio of the power of the main beam B1 to the sum of the power of the eight sub-beams B2 is 0:10 to 4:6, thereby making it possible to suppress the occurrence of welding defects such as blowholes.

[0041] 3A and 3B, the eight sub beams B2 in the laser light L are positioned so as to form a substantially ring shape with the main beam B1 at the center, so that even if the sweep direction is changed from the sweep direction SD shown in Fig. 3A and 3B to any direction, some of the sub beams B2 will be positioned in front of the main beam B1 in the changed sweep direction. Therefore, the effect of suppressing the occurrence of welding defects can be achieved for any sweep direction.

[0042] Next, as an experimental example, an experiment was conducted in which a laser beam was irradiated onto A6061 plate materials with thicknesses of 2 mm and 1 mm, using a laser welding device with the configuration shown in Figure 1. The wavelength of the laser beam output from the laser device was 1070 nm, and the power was 12 kW. In addition, the experiment was conducted both without and with a diffractive optical element (DOE).

[0043] When using a DOE, as shown in FIG. 4, seven DOEs were prepared, each designed to split the laser light into a main beam and 16 sub-beams positioned to form an approximately ring shape around the main beam. The diameter 2R of this ring shape was set to 921 μm on the surface of the workpiece. The sweep direction was the upward direction in the drawing. Each DOE was designed to have the same power of the 16 sub-beams. The beam diameters (spot diameters) of the main beam and the sub-beams were both set to 267 μm. Lap welding tests were performed with the ratio of the power of the main beam to the sum of the power of the 16 sub-beams set to 1:9 for the workpieces W, each of which was made of aluminum members W1 and W2 with a plate thickness of 2 mm, and with the ratios of the power of the main beam to the sum of the power of the 16 sub-beams set to 1:9 and 3:7 for the workpieces W, each of which was made of aluminum members W1 and W2 with a plate thickness of 1 mm. If the ratio of the power of the main beam to the sum of the powers of the 16 sub-beams is 1:9, then the ratio of the power of the main beam to the power of one sub-beam is 1:9 / 16=16:9, and if the ratio is 3:7, then the ratio of the power of the main beam to the power of one sub-beam is 3:7 / 16=48:7.

[0044] The processing object W was lap-welded under conditions in which the sweep speed of the laser light relative to the processing object was changed between 8.3 mm / sec and 300 mm / sec, and the laser output was changed between 3 kW and 11 kW.

[0045] Figure 5 shows the results of lap welding with different processing speeds and output (A6061, plate thickness 2 mm each, main beam to sub-beam power ratio 1:9). The power ratio (center:periphery) indicates the ratio of the power of the main beam to the total power of the sub-beam. The symbols "◎", "〇", "△", "▽", and "×" indicate the visual judgment of the condition of the irradiated area (irradiated area condition), and the numbers in parentheses indicate the number of blowholes that occurred based on the observation of the inside of the welded part using an X-ray CT scanner. Specifically, the symbol "◎" indicates that the irradiated area condition is good. The symbol "〇" indicates that the irradiated area condition is good, but peeling occurred during the driver check. The symbol "△" indicates that the irradiated area condition is good, but the number of blowholes is large. The symbol "▽" indicates that the bead has penetrated through to the back. The symbol "×" indicates non-welding.

[0046] As shown in Fig. 5, for example, when the plate thickness of aluminum members W1 and W2 is 2 mm each, and the power ratio of the main beam to the sub-beam is 1:9, the surface condition of the bead is good and the occurrence of blowholes is suppressed under the conditions of a sweep speed of 83.3 mm / sec to 300 mm / sec and a laser output of 5 kW to 11 kW. According to the results in Fig. 5, it was found that even when the processing speed is increased, by increasing the laser output, the surface condition is excellent and the occurrence of blowholes can be suppressed.

[0047] On the other hand, in the case of inappropriate conditions, for example, welding conditions in which DOE is not used or the DOE is not optimized, the bead surface is uneven and many blowholes occur, as shown in Figures 7A and 7B. In Figures 7A and 7B, W3 is the bead and W4 is the blowhole. Figures 6A and 6B, in which DOE is used under optimal conditions, show that the surface condition of bead W3 is smooth and no blowholes W4 occur, compared to when DOE is not used or is not optimized.

[0048] In addition, by observing the cross section of the molten pool during welding, when the DOE was used under optimal conditions (power ratio of the main beam to the sub-beams: 1:9), no gas was observed in the molten pool, and as a result, no blowholes were present. However, when the welding conditions were inappropriate (DOE was not used or the DOE was not optimized), gas was explosively generated near the front and center of the keyhole, and the gas was not completely released during cooling and remained as a blowhole. When welding the workpiece W containing aluminum, it is presumed that gas is generated and remains as a blowhole if the laser irradiation amount per unit area becomes too large. Therefore, it is preferable to control the power ratio between the main beam B1 and each sub-beam B2 so that it does not become too large. It is preferable that the power ratio between the main beam B1 and each sub-beam B2 is about 1:1 to 10:1. When the total power ratio between the main beam B1 and multiple sub-beams B2 is 0:10, it is preferable that the power ratio of each sub-beam B2 is about the same. The sub-beams may all have the same power or one or some of the sub-beams may have a higher power than the other sub-beams, but it is preferable to control the power ratio between the most powerful main beam and the least powerful sub-beam to be less than 10:1.

[0049] In the above embodiment, the split main beam B1 and the multiple sub-beams B2 do not overlap with each other. However, when the main beam and the sub-beams, or the sub-beams, are arranged so as to overlap with each other, it is preferable to control the amount of laser irradiation to the overlapping portion of the beams so as not to become too large.

[0050] Next, for the workpieces W, which were aluminum members W1 and W2 each with a plate thickness of 1 mm, the workpieces W were lap-welded under the following conditions: the ratio of the power of the main beam to the sum of the power of the 16 sub-beams was 1:9, the sweep speed of the laser light relative to the workpieces W was varied between 8.3 mm / sec and 200 mm / sec, and the laser output was varied between 4 kW and 8 kW.

[0051] Figure 8 shows the results of lap welding with different processing speeds and output (A6061, plate thicknesses of 1 mm each, main beam to sub-beam power ratio of 1:9). As shown in Figure 8, as an example, under the conditions of aluminum members W1 and W2 each having a plate thickness of 1 mm and a main beam to sub-beam power ratio of 1:9, the bead surface condition was good and the occurrence of blowholes was suppressed under the conditions of a sweep speed of 33.3 to 200 mm / sec and a laser output of 5 kW to 8 kW.

[0052] Furthermore, for the workpieces W, which were aluminum members W1 and W2 each having a plate thickness of 1 mm, the workpieces W were lap-welded under the following conditions: the ratio of the power of the main beam to the sum of the power of the 16 sub-beams was 3:7, the sweep speed of the laser light relative to the workpieces W was 100 mm / sec to 300 mm / sec, and the laser output was changed between 3 kW and 8 kW.

[0053] Figure 9 shows the results of lap welding with different processing speeds and output (A6061, plate thicknesses of 1 mm each, main beam to sub-beam power ratio of 3:7). As shown in Figure 9, as an example, under the conditions of aluminum members W1 and W2 each having a plate thickness of 1 mm and a main beam to sub-beam power ratio of 3:7, the bead surface condition was good and the occurrence of blowholes was suppressed under the conditions of a sweep speed of 100 mm / sec to 300 mm / sec and a laser output of 4 kW to 6 kW.

[0054] Next, under the conditions of Fig. 8, the beam diameter (spot diameter) of the main beam and the sub beam was reduced from 267μm to 213μm, and the power density of the main beam and the sub beam was increased to perform lap welding on the workpiece W. As a result, as an example, under conditions of a laser output of 4kW and a sweep speed of 16.7mm / sec to 20mm / sec, the surface condition of the bead became good and the occurrence of blowholes was suppressed. Comparing this result with the result of Fig. 8, it can be seen that when the beam diameter of the main beam and the sub beam is reduced and the power density is increased, the conditions (processing window) under which suitable welding can be achieved tend to shift to the lower output side for the laser output and the lower speed side for the sweep speed.

[0055] Furthermore, experiments were conducted by changing the material of the aluminum members W1 and W2. That is, for the workpiece W, which was made of aluminum members W1 and W2 made of A5052 and had a plate thickness of 2 mm each, the workpieces W were lap-welded under the following conditions: the ratio of the power of the main beam to the total power of the 16 sub-beams was 1:9, the beam diameter (spot diameter) of the main beam and the sub-beams was 267 μm, the sweep speed of the laser light relative to the workpiece W was 16.7 mm / sec to 200 mm / sec, and the laser output was changed between 6 kW and 12 kW.

[0056] Fig. 10 shows the results of lap welding with different processing speeds and output (A5052, plate thicknesses of 2 mm each, main beam to sub-beam power ratio of 1:9). As shown in Fig. 10, as an example, under the conditions of the plate thicknesses of the aluminum members W1 and W2 being 2 mm each and the power ratio of the main beam to sub-beam being 1:9, the bead surface condition was good and the occurrence of blowholes was suppressed under the conditions of a sweep speed of 16.7 mm / sec to 183.3 mm / sec and a laser output of 6 kW to 12 kW. In particular, the particularly preferable conditions for the number of blowholes to be 10 or less are as follows: Laser output is 12kW, and sweep speed is 116.7mm / sec~183.3mm / sec. Laser output is 11kW and sweep speed is 116.7mm / sec~150mm / sec. Laser output is 10kW and sweep speed is 100mm / sec~133mm / sec. Laser output is 9kW and sweep speed is 100mm / sec~116.7mm / sec.

[0057] Furthermore, under the conditions of Fig. 10, the plate thicknesses of the aluminum members W1 and W2 were each changed to 1 mm, and the workpiece W was lap-welded. The power ratio of the main beam to the sub-beam was changed to 3:7. As a result, as an example, the bead surface condition was improved and the occurrence of blowholes was suppressed under the conditions of a laser output of 4 kW and a sweep speed of 150 mm / sec to 225 mm / sec, a laser output of 5 kW and a sweep speed of 150 mm / sec to 275 mm / sec, and a laser output of 6 kW and a sweep speed of 200 mm / sec to 300 mm / sec.

[0058] Further, under the conditions of FIG. 10, the plate thickness of the aluminum members W1 and W2 was changed to 1 mm each, the beam diameter of the main beam and the sub-beam was reduced from 267 μm to 213 μm, and the power density of the main beam and the sub-beam was increased to perform lap welding of the workpiece W. The power ratio of the main beam to the sub-beam was 5:5 or 3:7. As a result, as an example, the surface condition of the bead was good and the occurrence of blowholes was suppressed under the conditions of a laser output of 5 kW and a sweep speed of 375 mm / sec to 450 mm / sec at a power ratio of 5:5, and a laser output of 5 kW and a sweep speed of 250 mm / sec to 300 mm / sec at a power ratio of 3:7. From this result, it can be seen that the range of the sweep speed at which suitable welding can be realized is different between the power ratio of 5:5 and the power ratio of 3:7. In addition, when comparing the results for main and sub beam diameters of 267 μm and 213 μm under conditions of plate thickness of 1 mm and power ratio of 3:7, it can be seen that when the beam diameters of the main beam and sub beam are reduced to increase the power density, the conditions for achieving suitable welding tend to shift toward lower laser output and higher sweep speeds.

[0059] Furthermore, under the conditions of FIG. 10, the aluminum member W1 on the opposite side to the laser light irradiation side was changed to A60601 with a plate thickness of 2 mm, and the workpiece W was lap-welded. As a result, as an example, the surface condition of the bead was good and the occurrence of blowholes was suppressed under the conditions of a laser power of 9 kW and a sweep speed of 100 mm / sec, a laser power of 10 kW and a sweep speed of 116.7 mm / sec, and a laser power of 11 kW and a sweep speed of 133 mm / sec. Note that these combinations of suitable laser power and sweep speed were the same even when the positions of the aluminum members W1 and W2 were interchanged. From this result, it can be seen that suitable welding can be achieved even for welding dissimilar aluminum members.

[0060] As described above, by irradiating a laser beam consisting of a main beam B1 and sub-beams arranged to surround the outer periphery of the main beam B1 onto a workpiece W containing aluminum, so that the power ratio of the main beam to the sub-beams is 0:10 to 4:7, preferably 9:1 to 3:7, it is possible to perform welding while suppressing the occurrence of blowholes.

[0061] (Another example of beam arrangement) In the above-mentioned first embodiment, the multiple sub-beams are positioned so as to surround the outer periphery of the main beam, but the arrangement of the beams is not limited to this.

[0062] For example, in the example shown in FIG. 11, the laser light L1 irradiated to the workpiece is split into a main beam B1 and three sub beams B2. All three sub beams B2 are located forward of the main beam B1 in the sweep direction SD. The power of the main beam B1 is greater than the power of each of the sub beams B2. The ratio of the power of the main beam B1 to the sum of the power of the three sub beams B2 is 0:10 to 4:6. Even with this arrangement, the occurrence of welding defects can be suppressed, as in the case of the first embodiment.

[0063] In addition, in the case of a beam arrangement in the forward direction as shown in Figure 11, the angle θ formed by the lines connecting the center of the main beam B1 and the centers of two adjacent sub-beams B2 is preferably 90° or less, more preferably 60° or less, and even more preferably 45° or less.

[0064] In addition, since it is preferable that the shape of the molten pool is nearly line-symmetrical with respect to the sweep direction SD, it is preferable that the three sub-beams B2 are also arranged so as to be line-symmetrical with respect to the sweep direction SD.

[0065] As shown in FIG. 6, when a DOE is used to split laser light into a main beam B1 and three sub beams B2 and the three sub beams are positioned forward of the main beam in the sweep direction, and the ratio of the power of the main beam B1 to the sum of the power of the three sub beams B2 is, for example, 1:9, then the ratio of the power of the main beam B1 to the power of one of the sub beams is 1:9 / 3=1:3.

[0066] In the example shown in FIG. 12, the laser light L2 irradiated to the workpiece is divided into a main beam B1, 16 sub beams B2, and 8 sub beams B3. The 16 sub beams B2 form a sub beam group G2 and are positioned to form an approximately ring shape with the main beam B1 at the center. The 8 sub beams B3 form a sub beam group G3 and are positioned to form an approximately ring shape with a diameter smaller than that of the sub beam B2 and are positioned to form an approximately ring shape with the main beam B1 at the center. The ratio of the power of the main beam B1 to the sum of the powers of the sub beams B2 and B3 is 0:10 to 4:6. Even with this arrangement, the occurrence of welding defects can be suppressed as in the case of the first embodiment.

[0067] 13A to 13G are schematic diagrams for explaining still another example of the arrangement of beams. In the example shown in FIG. 13A, the laser light L31 includes a main beam B1 and 12 sub beams B2. The 12 sub beams B2 are positioned so as to form an approximately ring shape or an approximately regular hexagon shape with the main beam B1 at the center. In the example shown in FIG. 13B, the laser light L32 includes a main beam B1 and 6 sub beams B2. The 6 sub beams B2 are positioned so as to form an approximately ring shape or an approximately regular hexagon shape with the main beam B1 at the center. In the example shown in FIG. 13C, the laser light L33 includes a main beam B1 and 10 sub beams B2. The 10 sub beams B2 are positioned so as to form an approximately ring shape or an approximately pentagon shape with the main beam B1 at the center. In the example shown in FIG. 13D, the laser light L34 includes a main beam B1 and 5 sub beams B2. The five sub beams B2 are positioned so as to form an approximately ring shape or a pentagon shape around the main beam B1. In the example shown in FIG. 13E, the laser light L35 includes the main beam B1 and a plurality of sub beams B2. The plurality of sub beams B2 are continuously overlapped and positioned so as to form an approximately ring shape or a hexagon shape around the main beam B1. In the example shown in FIG. 13F, the laser light L36 includes the main beam B1 and a plurality of sub beams B2. The plurality of sub beams B2 are continuously overlapped and positioned so as to form an approximately ring shape or a pentagon shape around the main beam B1. In the example shown in FIG. 13G, the laser light L37 includes the main beam B1 and 16 sub beams B2. The 16 sub beams B2 are positioned so as to form an approximately ring shape or an approximately octagon shape around the main beam B1. Furthermore, when a matrix M is defined, the main beam B1 and the sub beam B2 are arranged so as to fill the rectangular grid.

[0068] As in the examples of Figures 13A to 13G, the main beam B1 and the sub beams B2 may be arranged to fill the grid, or may be arranged more freely. In the examples shown in Figures 13A to 13G, the sweep direction of the laser beams L31 to L37 may be arbitrary, and may be a direction deviated from the diagonal of the pentagon or hexagon. The number of sub beams that are not present in front of the sweep direction may be slightly reduced if the sub beams are densely arranged as in Figures 13A, 13C, 13F, and 13G.

[0069] (Embodiment 2) 14 is a diagram showing a schematic configuration of a laser welding apparatus according to embodiment 2. The laser welding apparatus 200 irradiates a workpiece W10 with a laser beam L to weld the workpiece W10. The workpiece W10 is formed by overlapping two plate-shaped aluminum members W11 and W12. The laser welding apparatus 200 realizes welding by the same operating principle as the laser welding apparatus 100. Therefore, only the device configuration of the laser welding apparatus 200 will be described below.

[0070] The laser welding device 200 includes a laser device 210 , an optical head 220 , and an optical fiber 230 .

[0071] The laser device 210 is configured similarly to the laser device 110, and is configured to be able 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.

[0072] 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 W10. The optical head 220 includes a collimator lens 221 and a condenser lens 222.

[0073] Furthermore, the optical head 220 has a galvano scanner disposed between the condenser lens 222 and the workpiece W10. The galvano scanner is a device that can move the irradiation position of the laser light L and sweep the laser light L without moving the optical head 220 by controlling the angles of two mirrors 224a and 224b. The laser welding device 200 is provided with a mirror 226 for guiding the laser light L emitted from the condenser lens 222 to the galvano scanner. Moreover, the angles of the mirrors 224a and 224b of the galvano scanner are changed by motors 225a and 225b, respectively.

[0074] The optical head 220 includes a diffractive optical element 223 as a beam shaper disposed between the collimator lens 221 and the condenser lens 222. The diffractive optical element 223 splits the laser light input from the collimator lens 221 into a main beam and a plurality of sub-beams, similar to the diffractive optical element 123. When sweeping, at least a part of the sub-beams is located forward of the main beam in the sweep direction. The power of the main beam is greater than the power of each sub-beam, and the ratio of the power of the main beam to the total power of the plurality of sub-beams is 0:10 to 4:6. This allows the laser welding device 200 to suppress the occurrence of welding defects when welding the workpiece W10. Note that the diffractive optical element 223 is disposed between the collimator lens 221 and the condenser lens 222 as in the first embodiment, but it may be disposed on the optical fiber 230 side of the collimator lens 221 or on the workpiece W10 side of the condenser lens 222.

[0075] (Embodiment 3) FIG. 15 is a schematic diagram showing a schematic configuration of a laser welding apparatus according to the third embodiment. The laser welding apparatus 300 irradiates the workpiece W20 with a laser beam L to weld the workpiece W20. The workpiece W20 is configured by placing two plate-shaped aluminum members W21 and W22 adjacent to each other so as to butt against each other. The laser welding apparatus 300 realizes welding by the same action principle as the laser welding apparatuses 100 and 200. The configurations of the elements other than the optical head 320 (the laser device 310 and the optical fiber 330) are the same as the corresponding elements of the laser welding apparatuses 100 and 200. Therefore, only the device configuration of the optical head 320 will be described below.

[0076] The optical head 320, like the optical heads 120 and 220, is an optical device for irradiating the workpiece W20 with the laser light input from the laser device 310. The optical head 320 includes a collimator lens 321 and a condenser lens 322.

[0077] Furthermore, the optical head 320 has a galvano scanner disposed between the collimator lens 321 and the condenser lens 322. The angles of mirrors 324a and 324b of the galvano scanner are changed by motors 325a and 325b, respectively. In the optical head 320, the galvano scanner is provided at a position different from that of the optical head 220. However, similar to the optical head 220, by controlling the angles of the two mirrors 324a and 324b, it is possible to move the irradiation position of the laser light L and sweep the laser light L without moving the optical head 320.

[0078] The optical head 320 includes a diffractive optical element 323 as a beam shaper disposed between the collimating lens 321 and the condenser lens 322. The diffractive optical element 323 splits the laser light input from the collimating lens 321 into a main beam and a plurality of sub-beams, similar to the diffractive optical elements 123 and 223. When sweeping, at least a part of the sub-beams is located forward of the main beam in the sweep direction. The power of the main beam is greater than the power of each sub-beam, and the ratio of the power of the main beam to the total power of the plurality of sub-beams is 0:10 to 4:6. This allows the laser welding device 300 to suppress the occurrence of welding defects when welding the workpiece W20. Also, the diffractive optical element 323 is disposed between the collimating lens 321 and the condenser lens 322 as in the first embodiment, but it may be disposed on the optical fiber 330 side of the collimating lens 321 or on the workpiece W20 side of the condenser lens 322.

[0079] (Embodiment 4) 16 is a diagram showing a schematic configuration of a laser welding apparatus according to embodiment 4. The laser welding apparatus 400 irradiates the workpiece W30 with laser beams L11 and L12 to weld the workpiece W30. The laser welding apparatus 400 realizes a welding method using the same principle of operation as the laser welding apparatus 100. Therefore, only the device configuration of the laser welding apparatus 400 will be described below.

[0080] The laser welding apparatus 400 includes a plurality of laser devices 411, 412 that output laser light, an optical head 420 that irradiates the laser light onto the workpiece W30, and optical fibers 431, 432 that guide the laser light output from the laser devices 411, 412 to the optical head 420.

[0081] The laser device 411 is configured similarly to the laser device 110, and is configured to be able to output, for example, a multi-mode laser beam L11 with an output of several kW. The laser device 412 is configured similarly to the laser device 110, and is configured to be able to output, for example, a multi-mode laser beam L12 with an output of several kW.

[0082] The optical fibers 431 and 432 guide the laser beams L11 and L12, respectively, to the optical head 420. The optical fiber 432 may be composed of a plurality of optical fibers or may be composed of a multi-core fiber in order to guide the laser beam L12, which is a plurality of laser beams.

[0083] The optical head 420 is an optical device for irradiating the laser beams L11 and L12 guided from the laser devices 411 and 412 toward the workpiece W30. The optical head 420 includes a collimator lens 421a and a condenser lens 422a for the laser beam L11, and a collimator lens 421b and a condenser lens 422b for the laser beam L12. The collimator lenses 421a and 421b are optical systems for temporarily collimating the laser beams guided by the optical fibers 431 and 432, respectively, and the condenser lenses 422a and 422b are optical systems for focusing the collimated laser beams on the workpiece W30. The collimator lens 421b and the condenser lens 422b may each be composed of a plurality of lenses to collimate or focus the laser beam L12, which is a plurality of laser beams.

[0084] The optical head 420 irradiates the workpiece W30 with the laser beam L11 as a main beam and the laser beam L12 as a sub beam of the laser beam L11 and L12, respectively. That is, the laser beam irradiated toward the workpiece W30 is composed of a main beam and multiple sub beams. When sweeping, at least a part of the multiple sub beams is located forward of the main beam in the sweep direction. The ratio of the power of the main beam to the sum of the powers of the multiple sub beams is 0:10 to 4:6. This allows the laser welding device 400 to suppress the occurrence of welding defects when welding the workpiece W30.

[0085] 3A, 3B, 4, 11, 12, and 13A to 13G can be realized by using the laser welding apparatus 400. Note that, although the examples shown in the figures use laser beams L11 and L12, the number of laser beams may be increased or decreased as appropriate.

[0086] (Embodiment 5) 17 is a diagram showing a schematic configuration of a laser welding apparatus according to embodiment 5. The laser welding apparatus 500 irradiates the workpiece W30 with laser beams L11 and L12 to weld the workpiece W30. The laser welding apparatus 500 realizes a welding method using the same action principle as the laser welding apparatus 100. Therefore, only the device configuration of the laser welding apparatus 500 will be described below.

[0087] The laser welding apparatus 500 includes a laser device 510 that outputs laser light, an optical head 520 that irradiates the laser light onto the workpiece W30, and optical fibers 531, 533, and 534 that guide the laser light output from the laser device 510 to the optical head 520.

[0088] The laser device 510 is configured similarly to the laser device 110, and is configured to be able to output, for example, a multi-mode laser beam with an output of several kW. The laser device 510 is used to output both laser beams L11 and L12 to be irradiated onto the processing object W30. For this purpose, a branching unit 532 is provided between optical fibers 531, 533, and 534 that guide the laser beam output from the laser device 510 to the optical head 520. The laser device 510 is configured to branch the laser beam output from the laser device 510 into a plurality of laser beams and then guide them to the optical head 520.

[0089] The optical fibers 531 and 533 guide the laser beams L11 and L12, respectively, to the optical head 520. The optical fiber 533 may be composed of a plurality of optical fibers or may be composed of a multi-core fiber in order to guide the laser beam L12, which is a plurality of laser beams.

[0090] The optical head 520 is an optical device for irradiating the laser beams L11 and L12, which are branched by the branching unit 532 and guided by the optical fibers 531 and 533, onto the workpiece W30. For this purpose, the optical head 520 includes a collimator lens 521a and a condenser lens 522a for the laser beam L11, and a collimator lens 521b and a condenser lens 522b for the laser beam L12. The collimator lenses 521a and 521b are optical systems for temporarily collimating the laser beams guided by the optical fibers 533 and 534, respectively, and the condenser lenses 522a and 522b are optical systems for focusing the collimated laser beams onto the workpiece W30. The collimator lens 521b and the condenser lens 522b may each be composed of a plurality of lenses in order to collimate or focus the laser beam L12, which is a plurality of laser beams.

[0091] The optical head 520 irradiates the workpiece W30 with the laser beam L11 as a main beam and the laser beam L12 as a sub beam of the laser beam L11 and L12, respectively. That is, the laser beam irradiated toward the workpiece W30 is composed of a main beam and a plurality of sub beams. In addition, when sweeping, at least a portion of the plurality of sub beams is located forward in the sweep direction relative to the main beam. The ratio of the power of the main beam to the sum of the powers of the plurality of sub beams is 0:10 to 4:6. This allows the laser welding device 500 to suppress the occurrence of welding defects when welding the workpiece W30.

[0092] 3A, 3B, 4, 11, 12, and 13A to 13G can be realized with laser welding apparatus 500. Note that, although the examples shown in the figures use laser beams L11 and L12, the number of laser beams may be increased or decreased as appropriate.

[0093] (Embodiment 6) 18 is a diagram showing a schematic configuration of a laser welding apparatus according to embodiment 6. The laser welding apparatus 600 irradiates a workpiece W30 with a laser beam L to weld the workpiece W30. The laser welding apparatus 600 realizes a welding method using the same action principle as the laser welding apparatus 100. Therefore, only the device configuration of the laser welding apparatus 600 will be described below.

[0094] The laser welding apparatus 600 includes a plurality of laser devices 611, 612 that output laser light, an optical head 620 that irradiates the laser light onto the workpiece W30, and optical fibers 631, 632, 635 that guide the laser light output from the laser devices 611, 612 to the optical head 620.

[0095] The laser device 611 is configured similarly to the laser device 110, and is configured to be able to output a multi-mode laser beam with an output of, for example, several kW. The laser device 612 is configured similarly to the laser device 110, and is configured to be able to output a plurality of multi-mode laser beams with an output of, for example, several kW.

[0096] In the laser welding apparatus 600, the laser beams output from the laser devices 611 and 612 are combined before being guided to the optical head 620. For this purpose, a combining section 634 is provided between optical fibers 631, 632, and 635 that guide the laser beams output from the laser devices 611 and 612 to the optical head 620. The laser beams output from the laser devices 611 and 612 are guided in parallel through the optical fiber 635.

[0097] Here, referring to Figs. 19A and 19B, configuration examples of the optical fiber 631 (and 632) and the optical fiber 635 will be described. As shown in Fig. 19A, the optical fiber 631 (and 632) is a normal optical fiber. That is, the optical fiber 631 (and 632) is an optical fiber in which a clad Cl having a lower refractive index than the core region Co is formed around one core region Co. On the other hand, as shown in Fig. 19B, the optical fiber 635 is a multi-core fiber. That is, the optical fiber 635 has two core regions Co1 and Co2, and a clad Cl having a lower refractive index than the core regions Co1 and Co2 is formed around the two core regions Co1 and Co2. Furthermore, the core region Co2 includes a plurality of core regions. Then, at the coupling portion 634, the core region Co of the optical fiber 631 and the core region Co1 of the optical fiber 635 are coupled, and the core region Co of the optical fiber 632 and the core region Co2 of the optical fiber 635 are coupled. Each of the multiple laser beams output from the laser device 612 is guided by each of the multiple core regions of the core region Co2.

[0098] Returning to Fig. 18, the optical head 620 is an optical device for irradiating the workpiece W30 with the laser light L combined by the combining portion 634. For this purpose, the optical head 620 includes a collimating lens 621 and a condensing lens 622 therein.

[0099] In the laser welding device 600, the optical head 620 does not include a diffractive optical element, nor does it have an independent optical system for multiple laser beams. However, the laser beams output from the laser devices 611 and 612 are combined before being guided to the optical head 620. As a result, the laser beam L irradiated toward the workpiece W30 is composed of a main beam and multiple sub-beams. In addition, when sweeping, at least a part of the multiple sub-beams is located forward in the sweep direction relative to the main beam. The ratio of the power of the main beam to the sum of the power of the multiple sub-beams is 0:10 to 4:6. As a result, the laser welding device 600 can suppress the occurrence of welding defects when welding the workpiece W30.

[0100] 3A, 3B, 4, 11, 12, and 13A to 13G can be realized by using the laser welding apparatus 600. Note that, although the examples shown in the figures use laser light output from the laser devices 611 and 612, the number of the laser devices may be appropriately increased or decreased.

[0101] As described above, in an embodiment of the present invention, by positioning multiple sub-beams of laser light so as to surround the outer periphery of the main beam, it is possible to suppress the occurrence of welding defects such as blowholes when laser welding workpieces containing aluminum, such as pure aluminum and aluminum alloys.

[0102] FIG. 20 is a diagram showing a schematic relationship between the beam profile of the laser light and the state of the workpiece. Beam profiles P1, P2, P3, and P4 show the case where the laser light is composed of a single beam. Beam profile P5 shows the case where the laser light is composed of a main beam and a sub-beam. Beam profile P51 is the profile of the main beam, and beam profiles P52 and P53 are the beam profiles of two of the sub-beams. The horizontal direction in FIG. 20 shows the spreading direction of each beam perpendicular to the central axis of each beam. For beam profile P5, the horizontal direction shows the spreading direction of each beam on a plane perpendicular to the central axis of the main beam and the two sub-beams located on either side of it. In addition, the vertical direction shows the power of each beam, the depth from the surface of the workpiece, the temperature of the workpiece, the state of the workpiece, etc.

[0103] Blowholes are likely to occur in welding of workpieces containing aluminum. The cause of blowholes is the vapor of the constituent metals that is generated in the keyhole that occurs during welding. For example, the beam profile P1 in Figure 20 is when the beam is focused on the workpiece, and the shape of the beam profile P1 roughly corresponds to the temperature distribution in the workpiece. In addition, the width of the beam profile P1 at the boundary between the solid phase and the liquid phase roughly corresponds to the melt width. Since the beam profile of a single beam in a focused state is steep, it indicates that at the position of the peak power, the temperature of the constituent metals of the workpiece reaches a temperature at which the metals become in a gas phase. In this case, the constituent metals are likely to bump and cause blowholes. In response to this, conventionally, the beam is defocused to expand the beam diameter, and the power density is reduced to make the beam profile gentler. This alleviates the steep temperature distribution that occurs at the beam irradiation point, suppressing the occurrence of blowholes. However, in the case of defocusing, the beam profile becomes like beam profile P2, and although the temperature of the constituent metals remains within the temperature range in the liquid phase even with the peak power, the beam width with the power to make the constituent metals liquid is narrower than in the case of the focused state. This means that although the beam diameter expands due to defocusing, the beam width of the part with the energy that actually contributes to melting the actual constituent metals does not become wider, that is, the melt width (bead width) does not become wider. In addition, in the case of defocusing, sufficient penetration depth cannot be obtained, or the sweep speed needs to be set to a slower speed. In other words, there is a trade-off between the occurrence of blowholes (welding quality) and the penetration depth and sweep speed. On the other hand, in order to obtain a sufficient melt width by defocusing, if the beam power is set so that the beam profile at the time of defocusing becomes beam profile P3, a high power is required so that the beam profile becomes beam profile P4 at the time of focusing. This also means that the defocusing technology does not effectively utilize the energy of the beam, especially the energy at the tail of the beam profile.

[0104] In contrast, the beam profile P5 includes the beam profile P51 of the main beam in a focused state and the beam profiles P53 and P54 of the sub beams. In this case, compared to the case where a single beam laser light having the total power of the main beam and the sub beams is irradiated in a focused state, the peak power can be suppressed to suppress the formation of blowholes due to bumping, and the melting depth and melting width can be made relatively large. Specifically, the temperature distribution T formed on the processing object in the case of the beam profile P5 is not steep like that of a single beam, and has a wide width that is the temperature of the liquid phase. Furthermore, the steep beam profile in the focused state is utilized, so that the melting depth can be made relatively deep with little energy waste, and it is also suitable for increasing the sweep speed. Note that the peak power of the beam profile P51 of the main beam is lower than that of the beam profiles P53 and P54 of the sub beams. However, since the position of the main beam is affected by the heat of the surrounding sub beams, the temperature of the processing object becomes higher than the temperature that can be reached by the main beam alone. Therefore, the temperature inside the keyhole formed in the workpiece can be precisely controlled by the individual power of the main beam and the sub beam, as well as the distance and power ratio between the main beam and the sub beam, so that metal vapor is not generated or is suppressed to an acceptable level, and an appropriate molten area (penetration depth and molten width) can be obtained. This well-balanced temperature distribution control realizes high-quality welding with suppressed blowhole generation. Note that "metal vapor is not generated or is suppressed to an acceptable level" means, for example, that the number of blowholes is determined to be "◎" in the above experimental example.

[0105] That is, one aspect of the present invention is a welding method in which a laser beam is irradiated onto an aluminum-containing workpiece, and the irradiated portion of the workpiece is melted and welded, the laser beam being composed of a main beam and a plurality of sub-beams, the plurality of sub-beams being positioned so as to surround the outer periphery of the main beam, and the temperature inside a keyhole formed in the workpiece is suppressed to an acceptable level or to no generation of metal vapor of the material constituting the workpiece, and the molten width is widened, compared to the case of irradiating a single beam of laser beam having a total power of the plurality of sub-beams and the main beam. Note that in the welded workpiece, the degree of generation of metal vapor can be confirmed, for example, by the number of blowholes, and the width of the molten width can be confirmed by the bead width.

[0106] The workpiece is not limited to a plate material, and the welding method is not limited to lap welding or butt welding. Therefore, the workpiece may be one in which at least two members to be welded are overlapped, in contact, or adjacent to each other.

[0107] When the laser beam is swept over the workpiece, the sweep may be performed by known wobbling or weaving to increase the surface area of ​​the molten pool.

[0108] Furthermore, the laser light used is not limited to multimode, and single mode laser light may be used.

[0109] The workpiece may be an aluminum plate having a thin metal layer on its surface, such as a plated aluminum plate. Although the workpiece has a thickness of about 1 mm to 10 mm, it may be thinner, about 0.01 mm.

[0110] Furthermore, the present invention is not limited to the above-mentioned embodiments. The present invention also includes configurations in which the components of the above-mentioned embodiments are appropriately combined. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-mentioned embodiments, and various modifications are possible. [Industrial Applicability]

[0111] The present invention is suitable for application to welding of workpieces containing aluminum. [Explanation of symbols]

[0112] 100, 200, 300, 400, 500, 600 Laser welding equipment 110, 210, 310, 411, 412, 510, 611, 612 Laser device 120, 220, 320, 420 Optical Head 121, 221, 321, 421a, 421b Collimating Lenses 122, 222, 322, 422a, 422b Condenser lenses 123, 223, 323 Diffractive optical elements 123a Diffraction Grating 130, 230, 330, 431, 432, 531, 533, 534, 631, 632, 635 Optical Fiber 224a, 224b, 226, 324a, 324b mirror 225a, 225b, 325a, 325b motor 532 Branch Unit 634 Joint B1 Main beam B2, B3 secondary beams G2, G3 sub-beam groups L, L´, L1, L2, L11, L12, L31, L32, L33, L34, L35, L36, L37 Laser light W, W10, W20, W30 Processing target W1, W2, W11, W12 Aluminum parts

Claims

1. An aluminum-containing workpiece is placed in an area to be irradiated with the laser light; The laser light is irradiated toward the processing object, and the processing object is melted at the irradiated portion to perform welding. the laser light is composed of a main beam and a plurality of sub-beams, A beam shaper divides the laser light into the main beam and the plurality of sub beams, and irradiates the main beam and the sub beams onto the processing object. the plurality of sub-beams are positioned so as to surround an outer periphery of the main beam and to form a substantially ring shape with the main beam as a center, and an outer diameter of the ring formed by the plurality of sub-beams is 300 μm to 2000 μm; the ratio of the power of the main beam to the sum of the powers of the plurality of sub-beams is between 0:10 and 4:6; The plurality of sub-beams have a beam diameter of 200 μm or more and 400 μm or less, While irradiating the laser light toward the object to be processed, the laser light and the object to be processed are moved relative to each other, and the laser light is swept over the object to be processed; At least a portion of the sub-beams is located forward of the main beam in a sweep direction.

2. 2. The welding method according to claim 1, wherein the workpieces are at least two members to be welded, and when the workpieces are placed in an area to be irradiated with the laser light, the at least two members are placed so as to overlap, contact, or be adjacent to each other.

3. The method of claim 1 or 2, wherein the beam shaper is a diffractive optical element.

4. The welding method according to any one of claims 1 to 3, wherein the workpiece is pure aluminum, an aluminum-copper alloy, an aluminum-magnesium alloy, an aluminum-silicon alloy, an aluminum-magnesium alloy, an aluminum-magnesium-silicon alloy, an aluminum-zinc-magnesium alloy, or an aluminum-zinc-magnesium-copper alloy.

5. A laser beam is irradiated onto an object to be processed, which includes aluminum, to melt the irradiated portion of the object to be processed and perform welding; the laser light is composed of a main beam and a plurality of sub-beams, A beam shaper divides the laser light into the main beam and the plurality of sub beams, and irradiates the main beam and the sub beams onto the processing object. the plurality of sub-beams are positioned so as to surround an outer periphery of the main beam and to form a substantially ring shape with the main beam as a center, and an outer diameter of the ring formed by the plurality of sub-beams is 300 μm to 2000 μm; the ratio of the power of the main beam to the sum of the powers of the plurality of sub-beams is between 0:10 and 4:6; The plurality of sub-beams have a beam diameter of 200 μm or more and 400 μm or less, While irradiating the laser light toward the object to be processed, the laser light and the object to be processed are moved relative to each other, and the laser light is swept over the object to be processed; At least a portion of the plurality of sub beams is located forward in a sweep direction relative to the main beam, In comparison with the case of irradiating a single beam of laser light having a total power of the plurality of sub-beams and the main beam, the temperature inside the keyhole formed in the object to be processed is suppressed to an acceptable level at which no metal vapor of the constituent material of the object to be processed is generated, and the melting width is widened. Welding method.

6. A laser device; an optical head that irradiates the laser light output from the laser device toward an object to be processed that includes aluminum, and melts and welds the irradiated portion of the object to be processed; A beam shaper; Equipped with The laser light irradiated to the processing object is composed of a main beam and a plurality of sub beams, the beam shaper splits the laser light into the main beam and the plurality of sub-beams; the plurality of sub-beams are positioned so as to surround an outer periphery of the main beam and to form a substantially ring shape with the main beam as a center, and an outer diameter of the ring formed by the plurality of sub-beams is 300 μm to 2000 μm; the ratio of the power of the main beam to the sum of the powers of the plurality of sub-beams is between 0:10 and 4:6; The plurality of sub-beams have a beam diameter of 200 μm or more and 400 μm or less, the optical head is configured so that the laser light and the workpiece are relatively movable, and the laser light is swept over the workpiece while melting and welding the workpiece; At least a portion of the plurality of sub-beams is located forward in a sweep direction relative to the main beam.

7. 7. The welding apparatus of claim 6, wherein the workpiece comprises at least two overlapping, contacting, or adjacent members to be welded.

8. 8. The welding apparatus of claim 6 or 7, wherein the beam shaper is a diffractive optical element.

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