LASER WELDING DEVICE AND METHOD FOR COMPONENT MANUFACTURING

Abstract

Laser welding device (1) designed to emit a beam (1a) to a welding surface (110) in at least one part of several elements (100) for performing laser welding, wherein the laser welding device (1) comprises: a emitter (10) designed to emit the beam to a main area (111, 205, 215) and a secondary area (112, 206, 216) on the welding surface, wherein the secondary area surrounds the main area, wherein the emitter is designed to emit the beam in such a setting that at least one peak occurs in both the main region and the secondary region, and is designed such that the beam emitted towards the main region has an average intensity that is higher than the average intensity of the beam emitted towards the secondary region, wherein the at least one peak is a state in which the intensity of the beam has a local maximum, and wherein the emitter (10) emits the beam (1a) in such a setting that at least one peak occurs in at least each of the areas of: a first point-shaped area (210) which is positioned in the main area (215), a third area (212) which is positioned in the adjacent area (216), wherein the third area is a ring-shaped area surrounding the first area; and a second area (211) which is positioned between the first area and the third area, wherein the second area is an annular area surrounding the first area, wherein the emitter (10) has a mode-setting device (12), wherein the mode-setting device (12) has a diffractive optical element (DOE) for setting a mode of the beam (1a), wherein the mode-setting device (12) is configured to set the beam (1a) in several modes, wherein, in a first mode, the intensity of the beam (1a) in the first region (210) is greater than the intensity of the beam in the third region (212), and the intensity of the beam in the third region (212) is greater than the intensity of the beam in the second region (211), and wherein, in a second mode, the intensity of the beam (1a) in the first region (210) is greater than the intensity of the beam in the second region (211), and the intensity of the beam in the second region (211) is greater than the intensity of the beam in the third region (212).

Description

[0001] The invention relates to a laser welding device and a method for producing a component by laser welding according to claims 1 and 2. BACKGROUND

[0002] The present disclosure is directed to a laser welding device and a method for producing a component by laser welding using the laser welding device.

[0003] Laser welding is known in which multiple elements are welded by irradiating a single beam. In a laser welding method described in Japanese Unexamined Patent Application Publication No. JP 2011-167709, the energy density distribution on an area irradiated by a welding beam conforms to a Gaussian distribution, and the peak energy density on the irradiated area is equal to or greater than a predetermined value. This reduces the occurrence of shrinkage cavities.

[0004] In the prior art, the subsequently published EP 3 590 648 A1 discloses a laser welding device and a method for producing a component by laser welding. The laser light is formed from a main beam and a secondary beam, wherein at least a portion of the secondary beam is directed onto the workpiece in front of the main beam in the welding direction, and the main beam has the same or greater energy density than the secondary beam.

[0005] EP 2 960 005 A1 discloses a laser welding device and a corresponding method for welding two components together. A first laser beam is directed in a point-like manner onto a boundary region between the first and second workpieces, and a second laser beam, also in a point-like manner, is applied to a laser beam spot on each of the two components, in front of and spaced from the first laser beam in the welding direction, so that the laser spots form an interrupted "V" shape to effect pre-melting. Alternatively, four second laser beam spots are also disclosed, so that an interrupted "X" pattern is formed in the welding area.

[0006] According to a third variant, four additional laser points of a third laser beam are directed onto the two components to be welded between the first laser point and the second four laser points in the interrupted "X" variant, so that a closed "X" is created by the adjacent laser points of the first laser beam up to the points of the second laser beam, in order to increase the melting and thus the welding speed. In another variant, the first laser beam is also split into four adjacent laser points.

[0007] US 2005 / 0 098 260 A1 describes a method and device for heating, in particular for welding, plastic using laser beams with the aid of a number of laser points in a focal plane. The laser beams are spatially split minimally, as if they were arranged on the same optical axis, allowing the geometric arrangement to be implemented with minimal adjustment.

[0008] DE 10 2016 218 938 A1 discloses a joining device and a joining method comprising laser radiation from a first, continuously emitting radiation source and a second, pulsed emitting radiation source. The two radiation sources are coupled into a common beam path of a coupler, so that a joining zone region of the second radiation extends across the entire width of the joining zone and is positioned upstream of a joining zone impact region of the first laser radiation at a predetermined distance in one joining direction.

[0009] Further related prior art is disclosed in JP 2015 - 205 327 A (laser welding method and device therefor) and DE 10 2010 003 750 A1 (method and arrangement for changing the beam profile characteristics of a laser beam by means of a multi-clad fiber).

[0010] The present invention is based on the object of increasing the weld seam strength during laser welding while simultaneously reducing spatter formation.

[0011] The problem is solved by independent claims 1 and 2. SUMMARY

[0012] Laser welding can also be performed using different types of lasers. The characteristics of lasers can, for example, cause spattering or lead to cases where a sufficiently deep molten pool is not formed, thus preventing a weld with sufficient strength. A molten pool is defined as a zone in which a base material is melted by the irradiation of the welding beam.

[0013] Preferably, the formation of spatter is reduced while at the same time achieving sufficient weld strength.

[0014] A laser welding apparatus according to the present disclosure is configured to irradiate a beam onto a surface to be welded (to emit a beam toward the welding surface) to perform laser welding in at least a portion of a plurality of elements, and includes an irradiator. The irradiator is configured to irradiate the beam toward a main region and a sub-region on the welding surface. The sub-region is positioned on the welding surface so that it is adjacent to or distant from the main region. A welding direction is a direction in which an irradiation region moves along the welding surface during laser welding. The sub-region also includes at least one zone positioned on a front side of the main region in the welding direction.The radiator is designed to emit the beam in such a way that at least one peak occurs in each of the main and secondary regions, and is designed so that the beam emitted to the main region has an average intensity that is higher than the average intensity of the beam emitted to the secondary region. Peak here refers to a state in which the beam intensity has a local maximum.

[0015] In the molten pool formed in the base material during laser welding, a portion of the molten base material migrates outward and generates spatter upon escaping from the molten pool. However, with the configuration of the present disclosure, a deep molten pool is formed on the welding surface in a zone including the main area, and a shallow weld pool is formed adjacent to the deep molten pool to reduce spatter. In this case, the portion of the molten base material that migrates outward in the deep molten pool of the main area is absorbed by the shallow molten pool adjacent to the deep molten pool; thereby, it is possible to prevent this portion of the molten base material from spreading externally as spatter.

[0016] In the configuration described above, the secondary region also includes at least one zone positioned on a front side of the main region in the welding direction. During laser welding in the welding direction, each radiation target area first receives a low-intensity beam directed toward the secondary region and then receives a high-intensity beam directed toward the main region. Accordingly, a rapid increase in the intensity of the beams to be emitted can be avoided, thus reducing the size and / or amount of spatter generated.

[0017] Beam distribution to the secondary area also allows for a large width of the deep molten pool formed in the primary area, resulting in improved weld strength. Accordingly, spatter formation can be reduced while maintaining sufficient weld strength.

[0018] The secondary area can be a zone surrounding the main area.

[0019] With such a design, regardless of the direction in which laser welding is performed, each radiation target area first receives a low-intensity beam directed toward the secondary area and then a high-intensity beam directed toward the primary area. Consequently, spatter formation can be reduced regardless of the laser welding direction, and there are no strict restrictions regarding the laser welding direction. Accordingly, laser welding can be performed more efficiently.

[0020] The radiator can also emit the beam in such a setting that at least one peak occurs in a central area positioned in the main area and in an outer area positioned in the secondary area and surrounding the central area.

[0021] With such a design, the intensity of the beam in the secondary area can be adjusted accordingly. The radiator may also emit the beam in such a setting that the at least one peak occurs in a first region positioned in the main region, in a third region positioned in the secondary region, and in a second region positioned between the first region and the third region.

[0022] With such a design, the melt pool formed in the main region can be widened, as well as a deep channel (“keyhole”) formed in the center of the melt pool in the main region can be widened to create a stable keyhole. As a result, improved weld strength of the multiple laser-welded elements can be achieved.

[0023] An intensity of the beam in the first region may be greater than an intensity of the beam in the third region, and the intensity of the beam in the third region may be greater than an intensity of the beam in the second region. With such a design, splash formation can be further reduced.

[0024] The intensity of the beam in the first region may be greater than the intensity of the beam in the second region, and the intensity of the beam in the second region may be greater than the intensity of the beam in the third region. With such a design, improved weld strength of the multiple laser-welded elements can be achieved.

[0025] The laser welding device may further comprise a beam generator configured to generate the beam by amplifying light emitted by a laser medium. The beam generator may adjust an intensity distribution of the beam generated by the beam generator using a change element for changing a light propagation direction.

[0026] With such a design, the beam intensity distribution can be flexibly adjusted. This allows for flexible adjustment of the tip positions, for example, depending on the size or properties of the base material, and enables the proper execution of laser welding of various base materials.

[0027] The radiator can be designed in such a way that it changes the intensity distribution of the beam generated by the beam generator by adjusting the changing element. With such a configuration, the beam intensity distribution can be easily adjusted, for example, depending on the base material. Accordingly, laser welding can be carried out properly. The laser welding device can be designed as a fiber laser. With such a design, laser welding can be carried out properly.

[0028] Furthermore, a component can be manufactured by laser welding multiple elements using the laser welding device described above. This manufacturing process reduces spatter during laser welding while simultaneously achieving sufficient weld strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] An embodiment of the present disclosure will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is an explanatory view showing a configuration of a laser welding apparatus; Fig. 2A is a table showing an intensity distribution and evaluation results of welding effects for each beam in a first to a fifth mode; Fig. 2B is an explanatory view showing a central region, a peripheral region, a main region, and a sub-region in the first mode; Fig. 2C is a graph showing an adjustment of the intensity distribution of the beam in the first mode; Fig. 3A is a graph showing measured values ​​of the intensity distribution of the beam in the first mode; Fig. 3B is an explanatory view showing a central region, a peripheral region, a main region, and a sub-region in the second mode; Fig. 3C is a graph showing an adjustment of the intensity distribution of the beam in the second mode; Fig. 4A is a graph showing measured values ​​of the intensity distribution of the beam in the second mode; Fig. 4B is a graph showing an adjustment of the intensity distribution of the beam in the third mode; Fig. Figure 4C is a graph showing measured values ​​of the intensity distribution of the beam in the third mode; Fig. 5A is an explanatory view of a molten pool formed by irradiating the beam in the first to fifth modes, respectively; Fig. 5B is an explanatory view showing a main area and a sub-area in a modified example of the first mode; and Fig. Figure 5C is a graph showing measured values ​​of the intensity distribution of the beam in the fifth mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present disclosure is not limited to the embodiment described below, but can be implemented in various forms within the technical scope of the present disclosure. [Description of the laser welding device]

[0031] A laser welding apparatus of the present embodiment radiates a beam to a welding surface in at least a portion of a plurality of elements to weld the plurality of elements by laser welding. Here, the plurality of elements may be, for example, elements made of iron or an iron alloy, elements made of a non-ferrous metal, or elements made of a non-metallic material. The welding surface may also be provided on an outer surface of one of the elements or may be provided across the respective outer surfaces of the elements. The laser welding apparatus may be configured, for example, as a fiber laser or may be configured as one of various types of lasers, such as solid-state lasers or gas lasers.

[0032] As in Fig. As shown in Figure 1, a laser welding device 1 includes a laser oscillator 30, a light path 20, and a processing head 10. The laser oscillator 30 excites a laser medium and amplifies light emitted by the excited laser medium to thereby generate a beam 1a. If the laser welding device 1 is configured as a fiber laser, a rare-earth-doped fiber can be used as the laser medium.

[0033] The light path 20 guides the beam 1a generated by the laser oscillator 30 to the processing head 10. To perform laser welding, the processing head 10 radiates the beam 1a to a plurality of elements 100, each of which is a base material. The processing head 10 includes a collimator 11, a mode setting device 12, a converging lens 13, and a position corrector 14. The processing head 10 does not need to include the position corrector 14.

[0034] The collimation device 11 is designed to adjust a direction of the beam 1a guided by the laser oscillator 30, for example by means of a lens and / or a mirror. The mode adjusting device 12 is configured to adjust a mode of the beam 1a using a changing element 12a such as a lens and / or a diffractive optical element (DOE) for changing a traveling direction of a light. "Mode" here means a distribution pattern of an intensity of the beam 1a in a radiation region of the beam 1a. The intensity of the beam 1a may be, for example, an energy density of the beam 1a. Specifically, the mode of the beam 1a is adjusted when the beam 1a, whose direction has been adjusted by the collimation device 11, passes through the lens or the like provided on the mode adjusting device 12. In one example, the mode change is performed by adjusting the changing element 12a provided on the mode adjusting device 12.

[0035] The converging lens 13 is designed to adjust a degree of convergence of the beam 1a, for which the mode has been set by the mode setting device 12. During welding, the degree of convergence of the beam 1a is adjusted so that the beam 1a converges immediately in front of the materials.

[0036] The position corrector 14 is designed to adjust a target position of the beam 1a after it passes through the converging lens 13. [Details about the modes]

[0037] As described above, the laser welding device 1 can radiate the beam in several modes. The modes can be set as appropriate, for example, depending on the dimensions of the base materials, the properties of the base materials, or the moving speed of a radiating region (a beam receiving region or beam target region) during laser welding. In at least some modes, the beam is radiated to a main region and a sub-region of the welding surface of the plurality of members 100 that are the base materials. The beam can be set to be partially radiated to each of the main and sub-regions, or can be set to be completely radiated to each of the main and sub-regions. The sub-region is positioned near the main region.Specifically, the secondary area can be positioned adjacent to the main area or at a predetermined or smaller distance from the main area. The secondary area also includes at least one zone on a front side of the main area in the welding direction. Welding direction here refers to the direction in which the irradiation area moves along the weld surface during laser welding.

[0038] An intensity of the beam radiated to the main area is higher than an intensity of the beam radiated to the sub-area. In particular, the laser welding device 1 radiates the beam in such a setting that at least one peak occurs in each of the main area and the sub-area. An average intensity of the beam radiated to the main area is also higher than an average intensity of the beam radiated to the sub-area. Peak here means a state with a local maximum of a beam intensity. Specifically, peak here means a state in which the beam intensity represents a relative maximum, that is, in which the beam intensity assumes a maximum value. Changes in the beam intensity around the peak alternate from increase to decrease. Hereinafter, the beam intensity at the peak is referred to as the "peak value."

[0039] The beam is radiated toward the main region to form a deep molten pool, thus welding the multiple elements 100, as explained in more detail below. Here, molten pool refers to a zone melted by irradiation of the beam within the multiple elements 100. Conversely, the beam is radiated toward the secondary region to form a shallow molten pool, thus reducing spatter. The molten pool formed in the secondary region is shallower than the molten pool formed in an area on the welding surface encompassing the main region, and is adjacent to this molten pool.

[0040] The present embodiment provides a plurality of modes including first to fifth modes, in which the above-described main area and sub-area are provided, respectively. The first to third modes will be described below. In the following, a dot-like area as shown in Fig. 2B, is referred to as the "central region." Furthermore, a plurality of circumferential regions surrounding the central region are referred to as the "first intermediate region," "second intermediate region," "third intermediate region," and "circumferential region." A size relationship between the respective radii of these regions is as follows: radius of the circumferential region > radius of the third intermediate region > radius of the second intermediate region > radius of the first intermediate region.

[0041] In the first mode according to the Fig. 2A and Fig. 2B, a beam is radiated to the welding surface in such a setting that peaks occur in a central region 200 and a peripheral region 201. Also, a beam intensity ratio between a peak value 200a in the central region 200 and a peak value 201a in the peripheral region 201, as in Fig. 2C, set to 7:3.

[0042] In one example, a circular region with a diameter of approximately several hundred micrometers around the central region 200 is thus a main region 205. Furthermore, an annular region that borders and surrounds the main region 205 is a secondary region 206. In other words, the main region 205 and the secondary region 206 are arranged coaxially. The main region 205 and the secondary region 206 may be arranged substantially coaxially. In the first mode, as in Fig. 2C, the beam is adjusted so that the radiation to the surface occurs in a state in which the beam radiated to the main area 205 has a higher intensity than the beam radiated to the sub-area 206. As shown in Fig. 3A, the intensity of the beam actually emitted to the main area 205 is accordingly higher than the intensity of the beam actually emitted to the secondary area 206.

[0043] In the second mode according to the Fig. 3B and Fig. 3C, a beam is radiated to the welding surface in such a setting that peaks occur in a central region 210, a first intermediate region 211 and a peripheral region 212. A size ratio between a first peak value 210a in the central region 210, a second peak value 211a in the first intermediate region 211 and a third peak value 212a in the peripheral region 212, as in Fig. 3C, is configured as follows: first peak value 210a > second peak value 211a > third peak value 212a. More specifically, in one example, a ratio between the first peak value 210a, the second peak value 211a, and the third peak value 212a is set to 8:2:1. The ratio can be appropriately set within a range in which the above-mentioned size relationship is maintained.

[0044] In one example, a circular region with a diameter of approximately several hundred micrometers around the central region 210 is a main region 215. Furthermore, an annular region that borders and surrounds the main region 215 is a secondary region 216. In other words, the main region 215 and the secondary region 216 are arranged coaxially. The main region 215 and the secondary region 216 can be arranged substantially coaxially. Furthermore, the central region 210 is arranged in the main region 215, and the peripheral region 212 is arranged in the secondary region 216. The first intermediate region 211 is arranged between the main region 215 and the peripheral region 212. In the second mode, as in Fig. 3C, the beam is radiated to the welding surface in such a setting that the beam radiated to the main area 215 has a higher intensity than the beam radiated to the secondary area 216. As shown in Fig. 4A, the intensity of the beam actually emitted to the main area 215 is accordingly higher than the intensity of the beam actually emitted to the secondary area 216.

[0045] In the third mode, similar to the second mode, a beam is emitted in such an orientation to the welding surface that peaks appear in the central region 210, the first intermediate region 211 and the peripheral region 212. As in Fig. However, as shown in Figure 4B, the third mode differs from the second mode in that the first to third peak values ​​210a to 212a have the following size ratio: first peak value 210a > third peak value 212a > second peak value 211a. Specifically, in the third mode, a ratio between the first peak value 210a, the second peak value 211a, and the third peak value 212a is set to 6:1.5:2.5 in one example. The ratio can be appropriately set within a range in which the above-mentioned size ratio is maintained.

[0046] In one example, a circular region with a diameter of approximately several hundred micrometers around the central region 210 is the main region 215, similar to the second mode. Furthermore, an annular region adjacent to and surrounding the main region 215 is the secondary region 216. In the third mode, as in Fig. 4B, the beam is radiated to the welding surface in such a setting that the intensity of the beam radiated to the main area 215 is higher than the intensity of the beam radiated to the secondary area 216. Accordingly, as shown in Fig. 4C, the intensity of the beam actually emitted to the main area 215 is higher than the intensity of the beam actually emitted to the secondary area 216. [Manufacturing process of a welded element]

[0047] In a method for manufacturing a welded member according to an embodiment of the present disclosure, first, a mode is selected depending on, for example, properties, dimensions, and so on of the plurality of members 100 to be laser welded, and the changing element 12a is selected depending on the selected mode. Subsequently, the selected changing element 12a is set in the laser welding device 1. Then, laser welding of the plurality of members 100 is performed by irradiating a beam from the laser welding device 1 as described above. A total thickness of the plurality of members 100 along an irradiation direction of the beam may be, for example, 4 mm or more. The beam may be irradiated in, for example, any of the first to third modes.Spot welding of the multiple elements 100 may also be performed, or the welding of the multiple elements 100 may be performed by moving an irradiation area in the welding direction. As a result of this welding, a welded element comprising the multiple welded elements 100 is produced. The welded element may, for example, be a component for use in vehicles, such as automobiles.

[0048] When the beam is irradiated to a welding surface, base materials are melted and form a molten pool in a main region and a sub-region, respectively. As described above, an intensity of the beam irradiated to the main region is higher than an intensity of the beam irradiated to the sub-region. That is, in a zone including the main region on the welding surface, a deep and appropriately wide molten pool is formed to weld the plurality of members 100 with sufficient strength. The beam can form a keyhole in the molten pool of the main region. The beam irradiated to the sub-region forms a molten pool that is adjacent to and shallower than the molten pool of the main region.

[0049] Fig. 5A shows a melt pool 120 formed by a beam in one of the first to third modes in the plurality of elements 100. The plurality of elements 100 are, for example, two stacked plate elements, and a beam is radiated to a melt surface 100 formed on an outer surface of an upper one of the plate elements of Fig. 5A. Then, the beam radiated to a main region 111 forms a deep molten pool 121, which reaches a lower one of the plate elements. Fig. 5A shows an example in which a keyhole 123 is formed in the center of the molten pool 121 of the main region. The beam radiated to a secondary region 112 forms a shallow molten pool 122 surrounding and adjacent to the molten pool 121 of the main region 111. A peripheral region is located in a zone where the shallow molten pool 122 is formed in the weld surface 110.

[0050] In the molten pool 121 of the main region 111, a portion of the molten base material migrates upward toward the welding surface and generates spatter when the portion of the molten base material erupts from a molten surface. In the present embodiment, however, the shallow molten pool 122 is formed in the sub-region 112 so that it is adjacent to the deep molten pool 121 of the main region 111. Accordingly, the portion of the molten base material that migrates toward the welding surface in the molten pool 121 of the main region 111 is absorbed by the molten pool 122 of the sub-region 112, preventing that portion of the molten base material from spreading externally as spatter. Accordingly, spatter generation can be reduced. [Modified examples]

[0051] In the first to third modes, the beam is adjusted so that peaks occur in the peripheral region or in the peripheral region and the first intermediate region. However, the beam can be adjusted so that peaks occur not in the aforementioned regions, but in one or more point-like or linear regions located on a front side of the central region in the welding direction.

[0052] Specifically, as in Fig. 5B illustrates, the beam can be adjusted, for example, such that a peak occurs in an arcuate portion 221 that is part of the peripheral region 201, rather than in the peripheral region 201 of the first mode. The portion 221 is located on a front side of a central region 220 in the welding direction 230. In this case, a main region 225 of circular shape is formed, and a secondary region 226 in strip shape is also formed adjacent to a front side of the main region 225 in the welding direction 230.

[0053] Furthermore, in the second or third mode, the beam can be adjusted, for example, so that peaks occur in an arcuate section that is part of the first intermediate region 211 and in another arcuate section that is part of the peripheral region 212, instead of in the intermediate region 211 and peripheral region 212. These sections are located on the front side of the central region in the welding direction. In this case, too, a circular main region is formed, and a strip-shaped secondary region is formed adjacent to the front side of the main region in the welding direction.

[0054] Even when using these modified examples, a deep molten pool similar to the molten pool in the first to third modes is formed on the weld surface in a zone encompassing the main area. Furthermore, the beam radiated to the secondary area forms a shallow molten pool adjacent to the front side of the molten pool in the main area in the welding direction. Similar to the first to third modes, a portion of the molten base material migrating upward in the molten pool of the main area is absorbed by the molten pool of the adjacent area, preventing this portion of the molten base material from spreading externally as spatter. [Comparison of the different modes]

[0055] Next, a description will be given of the effects on welding when laser welding is performed in each of the above-described first to third modes and in a fourth mode, each of which is an example of the present disclosure. A description will also be given of the effects on welding when laser welding is performed in a fifth mode as a comparison example with the first four modes.

[0056] In the fourth mode, a beam is irradiated in such a way that the peaks appear in a central area and a peripheral area, similar to the first mode, and the beam intensity ratio between the central area and the peripheral area is set to 7:3. Thus, the beam is also irradiated in a circular area in the fourth mode. However, in the fourth mode, the degree of convergence of the beam is insufficient, and thus the beam is not sufficiently focused immediately in front of the base material. Accordingly, the irradiation area is broadened in the fourth mode, as shown in Fig. 5C can be seen.

[0057] In the fifth mode according to Fig. 2A, a beam is directed at a welding surface in such a way that a peak occurs only in a central area. In the fifth mode, the beam is directed onto a circular area surrounding the central area. This means that in the fifth mode, similar to the first to third modes, the beam is directed only to the main area and is not directed to the secondary area.

[0058] Fig. Figure 2A shows the respective beam intensity ratios (hereinafter referred to as measured value ratios) of the first to third intermediate regions and the peripheral region relative to the central region, respectively, for use in the first to fifth modes. Specifically, the measured value ratio is a ratio of a measured value of the beam intensity in the respective region to a measured value of the beam intensity in the central region, and for the calculation, the beam intensity in the central region is assumed to be 100. Fig. Figure 2A also shows a degree of spatter reduction using three levels A to C and an evaluation result for the respective weld strength when using the first to fifth modes.

[0059] The grading is done from low to high in the order of C, B, and A. If the weld strength evaluation result is "A," the molten pool in the main area has a large width and a keyhole is formed in the molten pool in a stable state. The spatter reduction degree indicates the degree of reduction in the amount and / or size of spatter.

[0060] The Fig. The evaluation results shown in Figure 2A are to be read as follows: (1) If the jet intensity is adjusted so that the measured value ratio of the third intermediate range is 1.2 or more, the degree of spatter reduction is improved. If the jet intensity is adjusted so that the measured value ratio of the third intermediate range is 1.5 or more, the degree of spatter reduction is also further improved. (2) If the beam intensity is adjusted so that the measurement ratio of the second intermediate region is 3.8 or more, the degree of spatter reduction is improved. In this case, too, the deep molten pool formed in the main region has a large width, and a keyhole is formed in the molten pool in a stable state, thereby achieving sufficient weld strength. The beam intensity can also be adjusted so that the measurement ratio of the second intermediate region is 3.8 or more and 4.6 or less. (3) If the beam intensity is adjusted so that the measured value ratio of the first intermediate range is 7 or more, similar effects to those in (2) can be achieved. The beam intensity can also be adjusted so that the measured value ratio of the first intermediate range is 7 or more and 8 or less. (4) In the case of setting with peaks in the central region, the first intermediate region, and the peripheral region, the relationship between a setting value of a peak value of the central region, a setting value of a peak value of the first intermediate region, and a setting value of a peak value of the peripheral region is specified as X0:Y0:Z0. When the value ranges of X0, Y0, and Z0 are set to 6 ≤ X0 ≤ 8, 1.5 ≤ Y0 ≤ 2, and 1 ≤ Z0 ≤ 2.5, respectively, similar effects to (2) can be achieved. (5) The ratio of the setting value of the peak value of the central region to the setting value of the peak value of the peripheral region is specified as X1:Z1. Setting the value ranges of X1 and Z1 to 6 ≤ X1 ≤ 8 and 1 ≤ Z1 ≤ 3, respectively, can reduce spatter while achieving sufficient weld strength. (6) The beam intensity can be adjusted so that the measured value ratio of the first intermediate range is 2 or more. The beam intensity can also be adjusted so that the measured value ratio of the first intermediate range is 2 or more, while X1 and Z1 are within the value ranges specified in (5) above. Under this condition, spatter formation can be reduced while achieving sufficient weld strength. (7) If the value ranges of X1 and Z1 are set to 6 ≤ X1 ≤ 8 and 1.5 ≤ Y1 ≤ 2.5, similar effects to (2) can also be achieved. The beam intensity can also be set so that the measured value ratio of the first intermediate range is 7 or more and / or the measured value ratio of the third intermediate range is 1.2 or more. Under this condition, similar effects to (2) can be achieved. (8) The beam intensity can also be adjusted so that the measured value ratio of the peripheral area is 0.6 or more. This improves the degree of spatter reduction. The beam intensity can also be adjusted so that the measured value ratio of the peripheral area is 3.0 or more. This further improves the degree of spatter reduction. The beam intensity can also be adjusted so that the measured value ratio of the peripheral area is 0.6 or more and 3.0 or less. Under this condition, a more suitable weld strength can be achieved. [Effects]

[0061] (1) A fiber laser has good light focusing properties and delivers high output power. Using a fiber laser for laser welding therefore results in the formation of a narrow, deep molten pool in the base material compared to using, for example, a CO2 laser. The molten pool is thus unstable, and a lot of spatter is generated. This requires a spatter shield to prevent spatter, and the provision of such a shield can hinder laser welding. Using a fiber laser for laser welding also results in a narrow welding area, and a keyhole formed in a molten pool is narrow and unstable, resulting in poor weld strength.

[0062] However, when the laser welding device 1 of the above-described embodiment is configured as a fiber laser, the shallow molten pool is formed adjacent to the molten pool of the main area as described above. This reduces the generation of spatter; thus, a spatter guard can be avoided or a smaller spatter guard can be used.

[0063] The secondary zone comprises at least one zone positioned at the front of the main zone in the welding direction. During laser welding in the welding direction, each radiation target zone first receives a low-intensity beam directed toward the secondary zone and then receives a high-intensity beam directed toward the main zone. This prevents a rapid increase in the intensity of emitted beams, thus reducing the amount and / or size of resulting spatter.

[0064] Beam distribution to the secondary zone also allows for a large, deep weld pool width in the primary zone, reducing width variation. This leads to improved weld strength and shortens the time required for laser welding.

[0065] Accordingly, spatter generation can be reduced while maintaining sufficient weld strength. Specifically, according to the laser welding apparatus 1 of the above-described embodiment, spatter generation can be reduced while maintaining sufficient weld strength, even when the base material has a thickness of, for example, 4 mm or more.

[0066] (2) According to the above-described embodiment, the main region and the sub-region are provided coaxially or substantially coaxially. Therefore, regardless of the laser welding direction, each radiation target region first receives a low-intensity beam toward the sub-region and then receives a high-intensity beam toward the main region. Accordingly, spatter generation can be reduced regardless of the laser welding direction, and there is no strict limitation on the laser welding direction. This means that it is possible to reduce one cause of directionality in laser welding, reduce the generation of spatter, and perform laser welding in all directions while reducing fluctuations in weld quality. Accordingly, laser welding can be performed more efficiently.

[0067] (3) In the second and third modes, an additional peak is set in the first intermediate region 211 in addition to the central region and peripheral region 212. Thus, compared to the first mode, the beam intensity around a boundary of the main region is high. Accordingly, the molten pool of the main region has a large width, and the keyhole formed in the center of the molten pool of the main region is widened, making the keyhole more stable. As a result, improved weld strength of the plurality of elements 100 can be achieved.

[0068] (4) In the first mode, the peak value of the first intermediate region 211 is smaller than the peak value of the peripheral region 212. This allows a further reduction of spatter formation.

[0069] (5) In the second mode, the peak value of the first intermediate region 211 is higher than the peak value of the peripheral region 212. With such a configuration, an improved weld strength of the plurality of elements 100 can be achieved.

[0070] (6) According to the laser welding apparatus 1 of the above-described embodiment, a beam is generated by amplifying light emitted from the laser medium, for example, using the laser oscillator 30. Then, the mode of the generated beam is set at the mode setting device 12 of the processing head 10. This enables flexible mode setting compared to, for example, a case where the mode is set in a beam generation step by the laser oscillator 30 or the like. Accordingly, the mode setting can be flexibly performed depending on the size or properties of the base material, for example, and laser welding of various base materials can be properly performed.

[0071] (7) The mode can be changed by changing the changing element 12a of the mode setting device 12. Accordingly, the mode setting can be flexibly adjusted according to, for example, the size or properties of the base material, and laser welding of various base materials can be properly performed. [Other embodiments]

[0072] (1) The modes of the laser welding apparatus 1 in the above-described embodiment are not limited to the first to third modes given as examples. Specifically, although in the first to third modes, the main region is circular and the sub-region is annular, the shape of the main region or sub-region can be modified, for example, by changing the shape of the central region or the peripheral region where a peak of the beam occurs. In the second and third modes, peaks are set in two concentrically arranged peripheral regions. However, peaks may be set, for example, in three or more concentrically arranged peripheral regions. That is, in the sub-region, peaks can be set in three or more regions. For example, peaks can also be set in two or more regions in the main region.

[0073] (2) In the laser welding apparatus 1 of the above-described embodiment, the beam mode is adjusted by passing the beam through a lens or the like provided on the mode adjusting device 12. However, the mode adjustment method is not limited to this. Specifically, the beam mode can be adjusted, for example, by superimposing beams generated by multiple laser oscillators.

[0074] (3) It may be possible to distribute a function performed by a single element in the above-described embodiment among multiple elements, or to integrate functions of multiple elements into a single element. Some of the configurations in the above-described embodiments may also be omitted, but only if the problems to be solved can be clarified. Any implementation that falls within the scope of the technical concept defined by the language of the appended claims may be an embodiment of the present disclosure. [Correspondence with claims]

[0075] The following explains how the terminology used to describe the above embodiment corresponds to the terminology recited in the appended claims.

[0076] The processing head 10 corresponds to an example of a radiator, and the laser oscillator 30 corresponds to an example of a beam generator. The central region 210 corresponds to an example of a first region, the first intermediate region 211 corresponds to an example of a second region, and the peripheral region 212 corresponds to an example of a third region. The first intermediate region 211, the peripheral region 211, and the peripheral region 212 each correspond to an example of an outer region.

Claims

[1] Laser welding device (1) designed to radiate a beam (1a) to a welding surface (110) in at least a part of a plurality of elements (100) for performing laser welding, the laser welding device (1) comprising: a radiator (10) designed to radiate the beam to a main area (111, 205, 215) and a secondary area (112, 206, 216) on the welding surface, the secondary area surrounding the main area, wherein the radiator is designed to emit the beam in such a setting that at least one peak occurs in each of the main region and the secondary region, and is designed such that the beam emitted to the main region has an average intensity that is higher than the average intensity of the beam emitted to the secondary region, wherein the at least one peak is a state in which an intensity of the beam has a local maximum, and wherein the radiator (10) emits the beam (1a) in such a setting that the at least one peak occurs in at least each of the regions of: a first point-shaped region (210) positioned in the main region (215), a third region (212) positioned in the secondary region (216), the third region being an annular region surrounding the first region; and a second region (211) positioned between the first region and the third region, the second region being an annular region surrounding the first region, the radiator (10) comprising a mode setting device (12), the mode setting device (12) comprising a diffractive optical element (DOE) for setting a mode of the beam (1a), the mode setting device (12) being configured to set the beam (1a) in a plurality of modes, wherein, in a first mode, the intensity of the beam (1a) in the first region (210) is greater than the intensity of the beam in the third region (212), and the intensity of the beam in the third region (212) is greater than the intensity of the beam in the second region (211), and wherein, in a second mode, the intensity of the beam (1a) in the first region (210) is greater than the intensity of the beam in the second region (211), and the intensity of the beam in the second region (211) is greater than the intensity of the beam in the third region (212). [2] Method of manufacturing a component by welding a plurality of elements (100) by laser welding, the method of manufacturing comprising the use of a laser welding device (1) according to the preceding claim 1.

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