Welding method and welding equipment

Abstract

To provide a new welding method and a welding device which, for example, can obtain required welding strength while suppressing spatters.SOLUTION: A welding method irradiates, for example, a processing object containing metal with a laser beam, melts the processing object in the irradiated part, and performs welding. The laser beam is composed of a main power region and at least one sub-power region, power of the main power region is equal to or more than power of the sub power region, a power ratio of the power of the main power region to a total of the power of the main power region and the power of the sub power region is within a range of 144:1 to 1:1. An aspect ratio of a depth of a weld mark to a width perpendicular to a sweeping direction of the weld mark formed in the processing object by relative movement of the laser beam to the processing object may be 0.8 or more.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Laser welding is known as a method 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 on the workpiece, and the energy of the laser beam melts the part. A pool of molten metal material called a molten pool is formed in the part irradiated with the laser beam, and the molten pool then solidifies to complete the welding.

[0003] Furthermore, 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] During welding, it is known that spatter is generated from the molten pool. Spatter is molten metal that has been scattered, and reducing its generation is important for preventing processing defects. Because spatter is molten metal that has been scattered, the generation of spatter also reduces the amount of metal material at the welded area. In other words, excessive spatter generation can lead to a shortage of metal material at the welded area, resulting in poor strength and other problems. Furthermore, the generated spatter adheres to the periphery of the welded area, and if it later peels off and adheres to electrical circuits, it can cause malfunctions in the electrical circuits. Therefore, welding electrical circuit components can be difficult.

[0006] Naturally, it is also important in this type of welding to obtain the required weld strength.

[0007] Therefore, one of the objects of the present invention is to provide a novel welding method and welding apparatus that can obtain a required welding strength while suppressing spatter, for example. [Means for solving the problem]

[0008] In a welding method of the present invention, for example, a laser beam is irradiated onto a workpiece including a metal, and the irradiated portion of the workpiece is melted and welded. The laser beam is composed of a main power region and at least one sub-power region, the power of the main power region is equal to or greater than the power of each of the sub-power regions, and the power ratio of the power of the main power region to the sum of the power of the at least one sub-power region is within a range of 144:1 to 1:1.

[0009] In the welding method, the laser light and the object to be processed move relatively to each other.

[0010] In the welding method, for example, the aspect ratio of the depth of the weld mark formed on the workpiece by the relative movement between the laser light and the workpiece to the width perpendicular to the sweep direction of the weld mark is set to 0.8 or more.

[0011] In the welding method, for example, the relative movement speed between the laser light and the object to be processed is not less than 2 [m / min] and not more than 30 [m / min].

[0012] In the welding method, for example, the relative movement speed is not less than 2 [m / min] and not more than 20 [m / min].

[0013] In the welding method, for example, the relative movement speed is not less than 5 [m / min] and not more than 10 [m / min].

[0014] Furthermore, the welding device of the present invention is, for example, composed of a laser oscillator and an optical head that receives light emitted from the laser oscillator to generate laser light, and irradiates the generated laser light toward an object to be processed to melt and weld the irradiated portion of the object to be processed, wherein the laser light is composed of a main power region and at least one sub-power region, the power of the main power region is equal to or greater than the power of each of the sub-power regions, and the power ratio of the power of the main power region to the sum of the power of the at least one sub-power region is within a range of 144:1 to 1:1.

[0015] In the welding device, the laser light and the workpiece move relative to each other. [Effects of the Invention]

[0016] According to the present invention, it is possible to suppress the occurrence of spatters and obtain the required welding strength. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is an exemplary schematic configuration diagram of a laser welding device according to the first embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing the concept of the principle of the diffractive optical element included in the laser welding apparatus of the first embodiment. [Figure 3] FIG. 3 is a schematic diagram showing an example of a beam (spot) of laser light irradiated from the laser welding device of the first embodiment on the surface of the processing target. [Figure 4] FIG. 4 is a schematic diagram showing another example of a beam (spot) of laser light irradiated from the laser welding device of the first embodiment on the surface of the processing target. [Figure 5] FIG. 5 is an exemplary schematic cross-sectional view showing a weld mark formed on an object to be processed by a laser beam irradiated from the laser welding device of the first embodiment. [Figure 6] FIG. 6 is an exemplary schematic configuration diagram of a laser welding device according to the second embodiment. [Figure 7] FIG. 7 is an exemplary schematic configuration diagram of a laser welding device according to the third embodiment. [Figure 8] FIG. 8 is a schematic diagram showing a schematic configuration of a laser welding device according to the fourth embodiment. [Figure 9] FIG. 9 is a schematic diagram showing a schematic configuration of a laser welding device according to the fifth embodiment. [Figure 10] FIG. 10 is a schematic diagram showing a schematic configuration of a laser welding device according to the sixth embodiment. [Figure 11] FIG. 11 is a diagram illustrating an example of the configuration of an optical fiber. [Figure 12] FIG. 12 is a diagram illustrating an example of the configuration of an optical fiber. [Figure 13] FIG. 13 is a schematic diagram showing a modified example of a beam (spot) of laser light irradiated from the laser welding device of the embodiment on the surface of the processing target. DETAILED DESCRIPTION OF THE INVENTION

[0018] Exemplary embodiments of the present invention are disclosed below. The configurations of the embodiments described below, as well as the actions and results (effects) brought about by the configurations, are merely examples. 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 derivative effects) obtained by the configurations.

[0019] The following embodiments have similar configurations. Therefore, according to the configurations of each embodiment, similar actions and effects based on the similar configurations can be obtained. Furthermore, in the following, similar configurations are given similar reference numerals, and duplicated explanations may be omitted.

[0020] In each figure, direction X is represented by an arrow X, direction Y is represented by an arrow Y, and direction Z is represented by an arrow Z. Directions X, Y, and Z intersect and are perpendicular to each other. The Z direction is the normal direction to the surface Wa (machining surface) of the workpiece W.

[0021] [First embodiment] [Laser welding equipment configuration] 1 is a diagram showing a schematic configuration of a laser welding apparatus according to a 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 laser welding apparatus 100 is an example of a welding apparatus.

[0022] The workpiece W of the laser welding apparatus 100 can be made of, for example, an iron-based metal material, an aluminum-based metal material, a copper-based metal material, or the like. The workpiece W has, for example, a plate shape, and the thickness of the workpiece W is, for example, not less than 1 mm and not more than 10 mm, but is not limited thereto. The workpiece W is made up of multiple members stacked one on top of the other. The number of members and the thickness of each member can be changed in various ways.

[0023] The laser device 110 includes a laser oscillator and is configured to be able to output laser light with a power of several kW, for example. The laser device 110 may also include, for example, a plurality of semiconductor laser elements therein, configured to be able to output 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, or a disk laser, and the laser light may be single-mode or multi-mode. The laser device 110 may also include various laser light sources, such as a fiber laser, a YAG laser, or a disk laser.

[0024] The optical fiber 130 guides the laser light output from the laser device 110 to the optical head 120 .

[0025] 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 condensing lens 122, and a DOE (diffractive optical element) 123. The collimating lens 121, the condensing lens 122, and the DOE 123 may also be referred to as optical components.

[0026] The optical head 120 is configured to be able to change its position relative to the workpiece W in order to sweep the laser light L while irradiating the laser light L 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.

[0027] The collimating lens 121 collimates the input laser light. The collimated laser light becomes parallel light. The condenser lens 122 condenses the parallel laser light and irradiates the laser light as laser light L (output light) onto the workpiece W.

[0028] The DOE 123 is disposed between the collimator lens 121 and the condenser lens 122, and shapes the shape of the laser beam (hereinafter referred to as the beam shape). As conceptually illustrated in FIG. 2, the DOE 123 has a configuration in which, for example, a plurality of diffraction gratings 123a with different periods are superimposed. The DOE 123 can shape the beam shape by bending the parallel light in a direction influenced by each diffraction grating 123a or by superimposing the diffraction gratings 123a. The DOE 123 may also be called a beam shaper.

[0029] [Beam (spot) shape] The DOE 123 splits the laser light input from the collimator lens 121 into multiple beams. Fig. 3 is a diagram showing an example of a beam (spot) of laser light L formed on the surface Wa of the workpiece W, and Fig. 4 is a diagram showing an example of a beam (spot) of laser light L' formed on the surface Wa of the workpiece W. Note that the arrow SD in Figs. 3 and 4 indicates the sweep direction of the beam on the surface Wa of the workpiece W. By replacing the DOE 123, the optical head 120 can output both the laser light L and the laser light L'.

[0030] The DOE 123 splits the laser light so that one main beam B1 spot and at least one sub beam B2 spot are formed on the surface Wa. In the example of Fig. 3, the beam shaping by the DOE 123 forms one main beam B1 spot and multiple sub beam B2 spots arranged in an annular shape around the main beam B1 spot on the surface Wa. In the example of Fig. 4, the beam shaping by the DOE 123 forms one main beam B1 spot and one sub beam B2 spot in an annular shape surrounding the main beam B1 spot on the surface Wa. The area irradiated with the main beam B1 is an example of a main power region, and the area irradiated with the sub beam B2 is an example of a sub power region.

[0031] The DOE 123 also shapes the beam so that at least a part of the spot of any one of the sub beams B2 is located in front of the spot of the main beam B1 in the sweep direction SD on the surface Wa. Specifically, any one of the sub beams B2 should be at least partially located in a region A in front of an imaginary line VL that passes through the front end B1f of the main beam B1 and is perpendicular to the sweep direction SD.

[0032] The main beam B1 and the sub-beam B2 have, for example, a Gaussian power distribution in the radial direction of the beam cross section. 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 diameter of the region of the peak intensity at or above the long axis (e.g., major axis) passing through the center of the beam or the short axis (e.g., minor axis) perpendicular to the long axis (e.g., major axis). 2 The length of the region where the intensity is equal to or greater than this is defined as the beam diameter. The power of each beam includes the peak of the beam and is 1 / e of the peak intensity. 2 The power is in the above-mentioned intensity range. By appropriately designing or adjusting the laser device 110, the optical fiber 130, the collimator lens 121, the condenser lens 122, and the DOE 123, it is possible to form the laser light L including the main beam B1 and the sub-beams B2 as described above.

[0033] [Welding method] In welding using the laser welding apparatus 100, first, the workpiece W is set in an area to be irradiated with the laser beam L. Then, the laser beam L and the workpiece W move relative to each other while the workpiece W is being irradiated with the laser beam L, which includes the main beam B1 and the sub-beams B2 split by the DOE 123. As a result, the laser beam L moves (sweeps) over the surface Wa while being irradiated onto the surface Wa in the sweep direction SD. The portion irradiated with the laser beam L melts and then solidifies as its temperature drops, thereby welding the workpiece W. Note that in this embodiment, as an example, the sweep direction SD is the X direction; however, the sweep direction SD is not limited to the X direction as long as it intersects with the Z direction.

[0034] Experimental studies by the inventors have confirmed that the occurrence of spatter can be suppressed by positioning at least a portion of the sub-beams B2 ahead of the main beam B1 in the sweep direction SD in the laser light L. This can be presumed to be because, for example, by preheating the workpiece W with the sub-beams B2 before the arrival of the main beam B1, the molten pool of the workpiece W formed by the sub-beams B2 and the main beam B1 becomes more stable.

[0035] [Experimental Results] FIG. 5 is a schematic diagram showing a cross section of the workpiece W perpendicular to the sweep direction SD. The inventors focused on the aspect ratio of the weld mark Wm formed on the cross section. The aspect ratio (d / w) is defined as the depth d of the weld mark Wm relative to the width w perpendicular to the sweep direction SD of the weld mark Wm. The weld mark Wm is the region of the so-called weld metal where melting and solidification (e.g., unidirectional solidification) have occurred, and does not include the surrounding heat-affected zone Ah. The width w is the width at the surface Wa, and the depth d is the depth from the surface Wa to the tip Wmt of the weld mark Wm. The width w conforms to JIS Handbook 40-1 Welding I (Basics), 4.1.6 Welding Design, 11605 "Weld Width," and the depth d conforms to JIS Handbook 40-1 Welding I (Basics), 4.1.6 Welding Design, 11619 "Penetration." If the aspect ratio (d / w) is small, it is thought that a sufficient depth d relative to the width w cannot be obtained and the heat-affected zone Ah becomes large, making it difficult to obtain the required weld strength.

[0036] The inventors performed laser welding by actually irradiating the workpiece W with laser light L having the beam shape shown in Figure 3 using the laser welding device 100 under several conditions shown in Table 1 below, and measured the aspect ratio (d / w) of the weld mark Wm in the cross section of the workpiece W. [Table 1]

[0037] In this experiment, the aspect ratio was measured when the ratio of the power of the main beam B1 to the sum of the powers of the sub-beams B2 (hereinafter referred to as the power ratio) was 3:7, 5:5 (=1:1), 7:3, and 9:1, and the relative movement speed (hereinafter referred to as the sweep speed) between the surface Wa and the laser light L was 30 [m / min], 20 [m / min], 10 [m / min], 5 [m / min], 2 [m / min], 1 [m / min], and 0.5 [m / min].

[0038] The wavelength of the laser light output from the laser device 110 was set to 1070 [nm], and the power was set to 6 [kW]. In each case where the power ratio was different, the sum of the power of the main beam B1 and the power of the multiple sub-beams B2 was set to be the same. The radius R (beam radius) of the circumference of the circle on which the sub-beams B2 are arranged around the center of the main beam B1 was set to 300 [μm].

[0039] Furthermore, a single sheet of stainless steel (SUS304) with a thickness of 10 mm was used as the workpiece W. When the workpieces W are stacked in the thickness direction TD (Z direction) and are in close contact with each other, it can be assumed that the aspect ratio is almost independent of the thickness and number of workpieces W. In other words, even when the workpieces W are multiple plate materials made of the same material stacked in close contact with each other in the thickness direction TD, it can be assumed that the same results as in this experiment, in which the workpiece W is a single plate material, will be obtained.

[0040] In Table 1, each row has a different sweep speed, and each column has a different power ratio. The numerical value at each point on the matrix indicates the aspect ratio when an experiment is conducted at the sweep speed of the row to which that point belongs and the power ratio of the column to which that point belongs. The numerical values ​​in the right column are a reference example, and indicate the aspect ratio for each sweep speed when there is no DOE 123 and the laser light irradiated onto the workpiece W has a single beam (spot).

[0041] From the experiments in Table 1, the following findings (1) to (5) were obtained. (1) When the power ratio was 5:5, 7:3, or 9:1, the aspect ratio was 0.8 or more, and practically acceptable weld strength was obtained. When the power ratio was 3:7, the aspect ratio was sometimes less than 0.8. (2) In the practical sweep speed range of 2 m / min to 30 m / min, when the power ratio was 5:5, 7:3, or 9:1, a larger aspect ratio was obtained at each sweep speed than when the power ratio was 3:7. In other words, a higher weld strength was obtained. (3) When the power ratio was 5:5, 7:3, or 9:1, the aspect ratios when the sweep speed was between 2 and 20 m / min were larger than the aspect ratio when the sweep speed was 30 m / min. This means that higher weld strength was obtained. (4) When the power ratio was 5:5, 7:3, or 9:1, the sweep speed at which the aspect ratio reached its maximum value, i.e., the weld strength reached its maximum, was within the sweep speed range of 5 m / min to 10 m / min. (5) Although not shown in Table 1, in the reference example, there was more spatter than when the power ratio was 5:5, 7:3, or 9:1, and the benefits of the laser light L including the main beam B1 and at least one sub-beam B2 were not obtained.

[0042] 3, the laser light L includes 16 sub-beams B2, with one sub-beam B2 located ahead of the main beam B1 in the sweep direction SD. Therefore, before the main beam B1 reaches the processing position on the surface Wa, it is mainly the one sub-beam B2 that heats the processing position. In other words, a power ratio of 9:1 is equivalent to a power ratio of 9:1 / 16 = 144:1.

[0043] From Table 1, it is preferable that the power ratio between the main beam and the total of one or more sub-beams is in the range of 9:1 to 1:1, in which case a high aspect ratio can be suitably achieved.

[0044] Furthermore, from Table 1, it is preferable that the sweep speed is 2 [m / min] or more and 20 [m / min] or less, in which case the aspect ratio can be made 1.1 or more.

[0045] Furthermore, from Table 1, it is more preferable that the sweep speed is 5 [m / min] or more and 10 [m / min] or less, in which case the aspect ratio can be made 1.6 or more.

[0046] This is thought to be because if the sweep speed is too fast, sufficient heat input is not obtained deep inside, resulting in a small depth d, and conversely, if the sweep speed is too slow, the heat input at the surface Wa becomes large, resulting in a large width w.

[0047] As described above, in this embodiment, for example, the ratio between the power of the main beam B1 (main power region) and the sum of the powers of at least one sub-beam B2 (sub-power region) is set within the range of 144:1 to 1:1.

[0048] According to this welding method and welding apparatus, it is possible to obtain a required welding strength while suppressing the generation of spatter.

[0049] In addition, in this embodiment, welding conditions such as the sweep speed (the relative movement speed between the laser light L and the workpiece W (surface Wa)) and power ratio are set so that the aspect ratio (d / w) of the weld mark Wm is 0.8 or more.

[0050] According to this welding method and welding apparatus, it is possible to obtain the required welding strength while suppressing the generation of spatter.

[0051] In this embodiment, the sweep speed is, for example, 2 [m / min] or more and 20 [m / min] or less.

[0052] In this embodiment, the sweep speed is, for example, 5 [m / min] or more and 10 [m / min] or less.

[0053] According to this welding method and welding apparatus, it is possible to obtain higher welding strength while suppressing the generation of spatter.

[0054] [Second embodiment] 6 is a diagram showing a schematic configuration of a laser welding apparatus according to a second embodiment. The laser welding apparatus 200 irradiates a workpiece W1 with laser light L to weld the workpiece W1. The workpiece W1 is formed by overlapping two plate-shaped metal members W11 and W12. The laser welding apparatus 200 achieves welding using the same operational principle as the laser welding apparatus 100. Therefore, only the configuration of the laser welding apparatus 200 will be described below.

[0055] The laser welding device 200 includes a laser device 210 , an optical head 220 , and an optical fiber 230 .

[0056] The laser device 210 includes a laser oscillator and 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.

[0057] The optical head 220, like the optical head 120, is an optical device for irradiating the workpiece W1 with the laser light input from the laser device 210. The optical head 220 includes a collimator lens 221 and a condenser lens 222.

[0058] Furthermore, the optical head 220 has a galvanometer scanner disposed between the condenser lens 222 and the workpiece W1. The galvanometer scanner 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 device 200 is provided with a mirror 226 for guiding the laser beam L emitted from the condenser lens 222 to the galvanometer scanner. Furthermore, the angles of the mirrors 224a and 224b of the galvanometer scanner are changed by motors 225a and 225b, respectively.

[0059] The optical head 220 includes a DOE 223 as a beam shaper disposed between a collimating lens 221 and a condenser lens 222. Like the DOE 123, the DOE 223 splits the laser light input from the collimating lens 221 to generate a main beam and at least one sub beam. At least a portion of the at least one sub beam is located forward in the sweep direction relative to the main beam. In this embodiment, the power ratio can be set in the same way as in the first embodiment.

[0060] [Third embodiment] FIG. 7 is a diagram showing a schematic configuration of a laser welding apparatus according to a third embodiment. The laser welding apparatus 300 irradiates a workpiece W2 with a laser beam L to weld the workpiece W2. The workpiece W2 is configured by two adjacent plate-shaped metal members W21 and W22 that are butt-jointed together. The laser welding apparatus 300 includes a laser oscillator and achieves welding using the same operating 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.

[0061] The optical head 320, like the optical heads 120 and 220, is an optical device for irradiating the workpiece W2 with the laser light input from the laser device 310. The optical head 320 includes a collimator lens 321 and a condenser lens 322.

[0062] Furthermore, optical head 320 has a galvanometer scanner disposed between collimator lens 321 and condenser lens 322. The angles of mirrors 324a and 324b of the galvanometer scanner are changed by motors 325a and 325b, respectively. In optical head 320, the galvanometer scanner is provided at a position different from that of optical head 220. However, similar to optical head 220, by controlling the angles of the two mirrors 324a and 324b, it is possible to move the irradiation position of laser light L and sweep laser light L without moving optical head 320.

[0063] The optical head 320 includes a DOE 323 as a beam shaper disposed between a collimating lens 321 and a condenser lens 322. Like the DOEs 123 and 223, the DOE 323 splits the laser light input from the collimating lens 321 to generate a main beam and at least one sub beam. At least a portion of the at least one sub beam is located forward in the sweep direction relative to the main beam. In this embodiment, the power ratio can be set in the same way as in the first embodiment.

[0064] [Fourth embodiment] 8 is a diagram showing a schematic configuration of a laser welding apparatus according to a fourth embodiment. The laser welding apparatus 400 irradiates the workpiece W with laser beams L11 and L12 to weld the workpiece W. The laser welding apparatus 400 realizes a welding method using the same operational principle as the laser welding apparatus 100. Therefore, only the configuration of the laser welding apparatus 400 will be described below.

[0065] 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 W, and optical fibers 431, 432 that guide the laser light output from the laser devices 411, 412 to the optical head 420.

[0066] 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 or single-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 laser beam L12 with an output of several kW, each of which is a plurality of multi-mode or single-mode laser beams.

[0067] 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 configured with a plurality of optical fibers or may be configured with a multi-core fiber in order to guide the laser beam L12, which is a plurality of laser beams.

[0068] The optical head 420 is an optical device for irradiating the laser beams L11 and L12 guided from the laser devices 411 and 412 onto the workpiece W. The optical head 420 includes a collimating lens 421a and a condensing lens 422a for the laser beam L11, and a collimating lens 421b and a condensing lens 422b for the laser beam L12. The collimating lenses 421a and 421b are optical systems for temporarily collimating the laser beams guided by the optical fibers 431 and 432, respectively, and the condensing lenses 422a and 422b are optical systems for focusing the collimated laser beams on the workpiece W. Note that the collimating lens 421b and the condensing lens 422b may each be composed of multiple lenses for collimating or focusing the laser beam L12, which is a plurality of laser beams.

[0069] The optical head 420 irradiates the workpiece W with the laser beam L11 as a main beam and the laser beam L12 as a sub-beam, out of the laser beams L11 and L12. That is, the laser beam irradiated toward the workpiece W is composed of the main beam and multiple sub-beams. When sweeping, at least a portion of the multiple sub-beams is positioned 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 9:1 to 5:5. This allows the laser welding apparatus 400 to suppress the occurrence of welding defects when welding the workpiece W. The ratio may be 144:1 to 5:5 depending on how the sub-beams are arranged.

[0070] The laser welding apparatus 400 can realize the arrangements shown in Figures 3 and 4. 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.

[0071] [Fifth embodiment] 9 is a diagram showing a schematic configuration of a laser welding apparatus according to a fifth embodiment. The laser welding apparatus 500 irradiates the workpiece W with laser beams L11 and L12 to weld the workpiece W. The laser welding apparatus 500 realizes a welding method using the same operational principle as the laser welding apparatus 100. Therefore, only the device configuration of the laser welding apparatus 500 will be described below.

[0072] 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 W, and optical fibers 531, 533, and 534 that guide the laser light output from the laser device 510 to the optical head 520.

[0073] The laser device 510 has the same configuration as the laser device 110, and is configured to be able to output, for example, a multimode 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 workpiece W. 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 multiple laser beams and then guide them to the optical head 520.

[0074] 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 configured with a plurality of optical fibers or may be configured with a multi-core fiber in order to guide the laser beam L12, which is a plurality of laser beams.

[0075] The optical head 520 is an optical device for irradiating the workpiece W with laser beams L11 and L12 branched by a branching unit 532 and guided by optical fibers 531 and 533. To this end, the optical head 520 includes a collimating lens 521a and a condensing lens 522a for the laser beam L11, and a collimating lens 521b and a condensing lens 522b for the laser beam L12. The collimating lenses 521a and 521b are optical systems for temporarily collimating the laser beams guided by the optical fibers 533 and 534, respectively, and the condensing lenses 522a and 522b are optical systems for focusing the collimated laser beams on the workpiece W. Note that the collimating lens 521b and the condensing lens 522b may each be composed of multiple lenses for collimating or focusing the laser beam L12, which is a plurality of laser beams.

[0076] The optical head 520 irradiates the workpiece W with the laser beam L11 as a main beam and the laser beam L12 as a sub-beam, out of the laser beams L11 and L12. That is, the laser beam irradiated toward the workpiece W is composed of the main beam and multiple sub-beams. When the laser beam is swept, at least a portion of the multiple sub-beams is positioned 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 9:1 to 5:5. This allows the laser welding apparatus 500 to suppress the occurrence of welding defects when welding the workpiece W. The ratio may be 144:1 to 5:5 depending on how the sub-beams are arranged.

[0077] The laser welding apparatus 500 can realize the arrangements exemplified in Figures 3 and 4. 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.

[0078] [Sixth embodiment] 10 is a diagram showing a schematic configuration of a laser welding apparatus according to a sixth embodiment. The laser welding apparatus 600 irradiates a workpiece W with laser light L to weld the workpiece W. The laser welding apparatus 600 realizes a welding method using the same operational principle as the laser welding apparatus 100. Therefore, only the configuration of the laser welding apparatus 600 will be described below.

[0079] 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 W, and optical fibers 631, 632, 635 that guide the laser light output from the laser devices 611, 612 to the optical head 620.

[0080] Laser device 611 is configured similarly to laser device 110 and is configured to be able to output, for example, a multi-mode laser beam with an output of several kW. Laser device 612 is configured similarly to laser device 110 and is configured to be able to output, for example, a plurality of laser beams with an output of several kW, each of which is multi-mode or single mode.

[0081] 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.

[0082] Here, with reference to FIGS. 11 and 12, exemplary configurations of the optical fiber 631 (and 632) and the optical fiber 635 will be described. As shown in FIG. 11, 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 cladding 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. 12, the optical fiber 635 is a multi-core fiber. That is, the optical fiber 635 has two core regions Co1 and Co2, and a cladding Cl having a lower refractive index than the core regions Co1 and Co2 is formed around these 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 is coupled to the core region Co1 of the optical fiber 635, and the core region Co of the optical fiber 632 is coupled to the core region Co2 of the optical fiber 635. Each of the plurality of laser beams output from the laser device 612 is guided by each of the plurality of core regions of the core region Co2.

[0083] Returning to Fig. 10, the optical head 620 is an optical device for irradiating the laser light L combined by the combining unit 634 onto the workpiece W. For this purpose, the optical head 620 includes a collimating lens 621 and a condensing lens 622 therein.

[0084] In the laser welding apparatus 600, the optical head 620 does not include a diffractive optical element, nor does it have independent optical systems 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 W is composed of a main beam and multiple sub-beams. Furthermore, when sweeping, at least a portion of the multiple sub-beams is positioned forward of the main beam in the sweep direction. The ratio of the power of the main beam to the sum of the power of the multiple sub-beams is 9:1 to 5:5. This allows the laser welding apparatus 600 to suppress the occurrence of welding defects when welding the workpiece W. Note that the ratio may be 144:1 to 5:5 depending on how the sub-beams are arranged.

[0085] 3 and 4. In the example shown in the figures, laser beams output from laser devices 611 and 612 are used, but the number of laser devices may be increased or decreased as appropriate.

[0086] In the above embodiment, the split main beam and the multiple sub-beams do not overlap each other, but the main beam and the sub-beams, or the sub-beams themselves, may overlap each other.

[0087] [Variations in the shape of the beam (spot)] Fig. 13 is a diagram showing an example of a beam (spot) of laser light L formed on the surface Wa of the workpiece W. In the example of Fig. 13, all of the sub-beams B2 are arranged in front of the main beam B1. Furthermore, since the ratio between the power of the main beam B1 and the power of the sub-beam B2 is 29:0.2, the ratio between the power of the main beam and the total power of the multiple (five) sub-beams is 29:1. This arrangement is preferable because it allows the workpiece to be preheated more effectively.

[0088] While the embodiments of the present invention have been described above, they 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, the specifications of each configuration, shape, and the like (structure, type, direction, model, size, length, width, thickness, height, number, arrangement, position, material, etc.) can be modified as appropriate.

[0089] For example, in each of the above embodiments, the welding mode of the main beam (main power region) may be keyhole welding or heat conduction welding. Keyhole welding here refers to a welding method that uses a keyhole. On the other hand, heat conduction welding refers to a welding method that melts the workpiece by utilizing heat generated when the laser beam is absorbed by the surface of the workpiece.

[0090] Furthermore, all the sub-beams may have the same power, or one or some of the sub-beams may have a higher power than the other sub-beams. Furthermore, multiple sub-beams may be classified into multiple groups, with the sub-beams in the same group having approximately the same power and the sub-beams in different groups having different powers. In this case, when comparing sub-beams classified into multiple different groups, the powers differ in stages. Note that the number of sub-beams included in a certain group is not limited to multiple, and may be just one.

[0091] Furthermore, the material to be processed is not limited to stainless steel.

[0092] Furthermore, the workpiece is not limited to plate materials, and the welding method is not limited to lap welding or butt welding. Therefore, the workpiece may be formed by overlapping, contacting, or adjacent two members to be welded.

[0093] When the laser beam is swept over the workpiece, the surface area of ​​the molten pool may be adjusted by known methods such as wobbling, weaving, or output modulation.

[0094] The object to be processed may also be a metal plated metal plate or the like, in which a thin layer of another metal is present on the surface of the metal. [Industrial Applicability]

[0095] The present invention can be used in a welding method and a welding apparatus. [Explanation of symbols]

[0096] 100, 200, 300...Laser welding equipment (welding equipment) 110, 210, 310...Laser device (laser oscillator) 120, 220, 320...Optical head 121, 221, 321...Collimating lenses 122, 222, 322...Condenser lens 123, 223, 323...DOE (diffractive optical element) 123a...diffraction grating 130, 230, 330...optical fiber 224a, 224b, 226, 324a, 324b...Mirror 225a, 225b, 325a, 325b...Motor 400...Laser welding equipment 411, 412...Laser device 420...Optical head 421a, 421b...Collimating lenses 422a, 422b...Condenser lenses 431, 432...Optical fiber 500...Laser welding equipment 510...Laser device 520...Optical head 521a, 521b...Collimating lenses 522a, 522b...Condenser lenses 531,534...Optical fiber 532...Branch unit 533...Optical fiber 600...Laser welding equipment 611,612...Laser device 620...Optical head 621...Collimating lens 622...Condenser lens 631, 632, 635...Optical fiber 634...Joining part A...Area (forward in the sweep direction) Ah...Heat affected area B1...Main beam (main power region) B1f…front end B2: Secondary beam (secondary power region) Cl...cladding Co, Co1, Co2...Core region d...depth L, L', L11, L12...Laser light R…radius SD: Sweep direction TD: thickness direction VL...imaginary line W, W1, W2...Processing target Wa...surface W11, W12, W21, W22...Metal parts Wm...welding marks Wmt...tip w…width X…direction Y...direction Z…direction (normal direction)

Claims

1. A laser beam is irradiated onto a workpiece including a metal and swept across the workpiece, thereby melting and welding the irradiated portion of the workpiece; the laser beam is configured by a main power region and at least one secondary power region spaced apart from the main power region and surrounding at least a portion of the periphery of the main power region including a portion forward in a sweep direction relative to the main power region; the power of the primary power region is equal to or greater than the power of each of the secondary power regions; a power ratio between the power of the primary power region and the sum of the power of the at least one secondary power region is in the range of 144:1 to 1:1; an aspect ratio of a depth of a welding mark formed on the processing object by the relative movement between the laser light and the processing object to a width perpendicular to a sweep direction of the welding mark is set to 0.8 or more; At least a portion of the secondary power region is located forward of the primary power region in the sweep direction to preheat the workpiece; A welding method in which the welding form by the main power region is keyhole welding.

2. A welding method as described in claim 1, wherein the secondary power region is arranged in a circular ring shape surrounding the main power region.

3. 3. The welding method according to claim 1, wherein a relative moving speed between the laser beam and the object is 2 m / min or more and 30 m / min or less.

4. 3. The welding method according to claim 1, wherein the relative movement speed is 2 m / min or more and 20 m / min or less.

5. 3. The welding method according to claim 1, wherein the relative movement speed is 5 m / min or more and 10 m / min or less.

6. a laser oscillator; an optical head that receives light oscillated from a laser oscillator, generates laser light, and irradiates and sweeps the generated laser light toward an object to be processed, thereby melting and welding the object at the irradiated portion; It is composed of the laser beam is configured by a main power region and at least one secondary power region spaced apart from the main power region and surrounding at least a portion of the periphery of the main power region including a portion forward in a sweep direction relative to the main power region; the power of the primary power region is equal to or greater than the power of each of the secondary power regions; a power ratio between the power of the primary power region and the sum of the power of the at least one secondary power region is in the range of 144:1 to 1:1; an aspect ratio of a depth of a welding mark formed on the processing object by the relative movement between the laser light and the processing object to a width perpendicular to a sweep direction of the welding mark is set to 0.8 or more; At least a portion of the secondary power region is located forward of the primary power region in the sweep direction to preheat the workpiece; A welding apparatus, wherein the welding form by the main power region is keyhole welding.

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