Laser welding method and laser welding device

Abstract

This laser welding method joins a plate-shaped first member formed from a metal material and a second member formed from a metal material by laser welding. The laser welding method comprises a configuration step and a laser irradiation step. In the arrangement step, the second member is brought into contact with or close to one main surface of the first member. In the laser irradiation step, the other main surface of the first member, which is the main surface on the opposite side of the one main surface, is irradiated with laser light. Furthermore, in the laser irradiation step, the first member and the second member are melted so as to form a welded section having a substantially circular or oval shape in plan view, and a fillet weld section is formed at the joint between the first member and the second member.

Description

[0001] This application is a divisional application of the following application:

[0002] The original application was filed on February 8, 2021.

[0003] The original application number was 202180012407.4.

[0004] The original invention application was titled: Laser welding method and laser welding apparatus. Technical Field

[0005] This invention relates to laser welding methods and laser welding apparatus. Background Technology

[0006] Laser welding is sometimes used when joining metal components together. Laser welding joins metal components by locally melting and solidifying the metal components through laser irradiation. Compared to methods such as resistance welding, laser welding offers advantages such as faster welding speed and less heat-affected zone.

[0007] Patent Document 1 discloses a laser welding method in which two metal plates are joined perpendicularly to each other, and a laser is irradiated along the joint to form a T-shaped or H-shaped steel section. In the method disclosed in Patent Document 1, two laser beams are simultaneously irradiated from both sides of the joined metal plates to opposite positions, and the irradiation points are moved in the same direction to perform welding.

[0008] Patent Document 2 discloses a method for manufacturing H-beams as follows: A single-pass welding process is performed by simultaneously irradiating a laser onto two T-shaped joints formed by pressing flange material against both ends of web material. In the method disclosed in Patent Document 2, laser welding is performed while the flange material is held in a state where the angle between it and the web material on the laser-irradiated side is smaller than the angle between it and the web material on the opposite side of the laser-irradiated side.

[0009] Patent Document 3 discloses a method for laser welding the upper guide rail and connecting bracket of a sliding component in the manufacture of a car seat. In the method disclosed in Patent Document 3, the lower surface of the connecting bracket, which has an L-shaped cross-section, overlaps the upper surface of the U-shaped cross-section portion of the upper guide rail, and lasers are irradiated on the overlapping two sides.

[0010] Patent document 4 discloses a method for welding T-joints and lap joints of structures by combining arc welding and laser welding.

[0011] Patent Document 5 discloses an apparatus for laser welding a cylindrical metal rod to a foil-shaped metal plate arranged parallel to the centerline of the metal rod. In the technology disclosed in Patent Document 5, the metal rod is arranged at a designated position on the metal plate arranged on a flat surface. Pressure is applied to the metal rod towards the metal plate using the two recesses of an inverted Y-shaped optical unit. In this state, a laser beam incident from the top of the optical unit is split into two branch paths to form a waveguide. The beam is focused by a focusing lens provided at the end of the branch path, and the laser is irradiated from both sides so that the focusing point is located near the position where the metal plate contacts the metal rod arranged on the metal plate.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Japanese Patent Publication No. 2005-21912.

[0015] Patent Document 2: Japanese Patent No. 5656220.

[0016] Patent document 3: Japanese Patent Publication No. 2019-69784.

[0017] Patent document 4: Japanese Patent No. 3907373.

[0018] Patent document 5: Japanese Patent No. 3935639. Summary of the Invention

[0019] However, previous technologies have the following problems (i) to (ix).

[0020] (i) In the past, the laser spot diameter and melting range were narrow, and the welding parts had to be correctly aligned. When the laser or the welding object was misaligned, the low margin made it impossible to join properly.

[0021] (ii) In conventional techniques, when the bevel precision of the welded components is poor, the resulting workpiece gap can cause the laser with a small spot diameter to pass through the irradiation area, or improper welding can lead to burn-through, incomplete penetration, or undercut, resulting in a significant decrease in fatigue strength. To avoid such situations, it is necessary to improve the bevel precision, which will result in a substantial increase in costs.

[0022] (iii) In conventional techniques, welding multiple overlapping components leads to increased thickness, requiring higher energy lasers to increase penetration. In this case, low-speed scanning can easily cause burn-through or porosity, while high-speed scanning can cause spatter, resulting in incomplete filling or bulging, making control difficult. Furthermore, the stacking can lead to the accumulation of precision errors in the components, and sometimes improper welding positions can result in incomplete bonding or insufficient bonding strength.

[0023] (iv) In the case of joining by laser welding, although the amount of angular deformation (strain) is smaller compared to the case of joining by arc welding, the amount of angular deformation (strain) must be prevented or corrected as disclosed in the above-mentioned Patent Document 2.

[0024] (v) In conventional techniques, the direction or range of laser irradiation is limited by the shape of the weld, resulting in only localized welding and insufficient strength. For example, when welding the outer circumferential surface of a tube against or close to the main surface of a plate material, the contact area is a line contact, so it can only be welded linearly, making it difficult to obtain sufficient strength.

[0025] (vi) In the prior art, the fillet weld portion is small or almost non-existent in the laser-irradiated area. In order to form a fillet weld, it is necessary to combine it with a combined arc welding as disclosed in the aforementioned Patent Document 4, or to add filler materials such as filler, or to additionally add a shape to the component that can form a fillet weld.

[0026] (vii) In conventional techniques, during continuous welding, the heat input increases as the welding progresses into the latter half. Furthermore, with a constant laser output, the heat input increases due to the decrease in scanning speed at the end, making burn-through control difficult.

[0027] (viii) In conventional techniques, multiple laser irradiations or the use of multiple laser heads are required to form fillet welds on both sides of T-joints, etc. This results in an increase in the number of processes or equipment costs. In addition, other equipment such as arc welding machines are sometimes required besides laser welding machines.

[0028] (ix) In the prior art, there are the following problems: when laser welding must be performed on the head of the laser welding device or in complex shapes or narrow positions that the laser cannot reach, a special laser welding device is required, or the structure needs to be modified in order to irradiate such positions, or multiple processes are required, etc.

[0029] The present invention was made in view of the aforementioned problems, and its object is to provide a laser welding method and laser welding apparatus that can form fillet welds with a large positional tolerance when welding metal components of various shapes to metal plates, and can form fillet welds without adding filler material even in the case of complex joint configurations, and can perform joints with high productivity and high strength.

[0030] One aspect of the present invention relates to a laser welding method for joining a plate-shaped first component made of metallic material to a second component made of metallic material by laser welding, comprising: a configuration step in which the second component abuts against or approaches a main surface of the first component; and a laser irradiation step in which a laser is irradiated onto a main surface opposite to the main surface of the first component that the second component abuts against or approaches, i.e., another main surface of the first component; wherein, in the laser irradiation step, the first component and the second component are melted to form a weld portion that is generally circular or oval in plan view and a fillet weld portion is formed at the joint of the first component and the second component. Attached Figure Description

[0031] Figure 1 This is a schematic diagram showing the configuration of the laser welding apparatus according to the first embodiment.

[0032] Figure 2A This is a perspective view illustrating a method of joining sheet materials together using laser welding, showing the configuration steps of arranging metal sheets together in a mating state.

[0033] Figure 2B This is a perspective view illustrating a method of joining sheet materials together using laser welding, showing the laser irradiation step of irradiating the upper surface of a metal sheet with a laser.

[0034] Figure 3 It is a top view showing the scanning trajectory of the laser spot during laser welding.

[0035] Figure 4 This is a top view showing the welded section.

[0036] Figure 5 It means Figure 4 A cross-sectional view of the VV line section.

[0037] Figure 6A It is a top view showing the positional relationship between the mating part of the metal plate and the annular center of the laser spot.

[0038] Figure 6B This is a front view showing the positional relationship between the mating parts of the metal plates and the annular center of the laser spot.

[0039] Figure 7 This is a cross-sectional view showing the welded portion formed by the laser welding method according to the second embodiment.

[0040] Figure 8 This is a perspective view (partial cross-sectional view) showing the welded portion formed by the laser welding method according to the third embodiment.

[0041] Figure 9 This is a perspective view (partial cross-sectional view) showing the welded portion formed by the laser welding method according to the fourth embodiment.

[0042] Figure 10 This is a perspective view (partial cross-sectional view) showing the welded portion formed by the laser welding method according to the fifth embodiment.

[0043] Figure 11A It is a top view showing the positional relationship between the metal plate and pipe and the center of the welded part.

[0044] Figure 11B It is a front view showing the positional relationship between the metal plate and pipe and the center of the welded part.

[0045] Figure 12 This is a perspective view (partial cross-sectional view) showing the welded portion formed by the laser welding method according to the sixth embodiment of the present invention.

[0046] Figure 13 This is a perspective view illustrating the laser welding method according to the seventh embodiment of the present invention.

[0047] Figure 14A This is a top view showing the generally circular weld portion formed by the laser welding method according to the eighth embodiment.

[0048] Figure 14B This is a top view showing the generally circular weld portion formed by the laser welding method according to the 9th embodiment.

[0049] Figure 14C This is a top view showing the generally circular weld portion formed by the laser welding method according to the 10th embodiment.

[0050] Figure 14D This is a top view showing the generally circular weld portion formed by the laser welding method according to the 11th embodiment.

[0051] Figure 14E This is a top view showing the generally circular weld portion formed by the laser welding method according to the 12th embodiment.

[0052] Figure 14F This is a top view showing the generally circular weld portion formed by the laser welding method according to the 13th embodiment.

[0053] Figure 15A This is a perspective view (partial cross-sectional view) showing the welded portion formed by the laser welding method according to the 14th embodiment.

[0054] Figure 15B This is a top view showing the welded portion formed by the laser welding method according to the 15th embodiment.

[0055] Figure 15C This is a cross-sectional view showing the welded portion according to the 15th embodiment.

[0056] Figure 16A This is a perspective view showing the welded portion formed by the laser welding method according to the 16th embodiment.

[0057] Figure 16B This is a cross-sectional view showing the welded portion according to the 16th embodiment.

[0058] Figure 16C This is a perspective view showing the welded portion formed by the laser welding method according to the 17th embodiment.

[0059] Figure 16D This is a cross-sectional view showing the welded portion according to the 17th embodiment.

[0060] Figure 17 This is a perspective view (partial cross-sectional view) showing a welded portion formed by the laser welding method according to the 18th embodiment of the present invention.

[0061] Figure 18A This is a perspective view illustrating the laser welding method involved in the embodiment.

[0062] Figure 18B This is a perspective view showing the laser welding method involved in the comparative example.

[0063] Figure 18C This is a cross-sectional view showing the shape deformation state of the steel plate in the T-joint formed by the laser welding method involved in the embodiment.

[0064] Figure 18D This is a cross-sectional view showing the shape deformation state of the steel plate in the T-joint formed by the laser welding method involved in the comparative example.

[0065] Figure 19AThis is a schematic diagram illustrating a method for testing the fatigue strength of samples as described in the embodiments.

[0066] Figure 19B This is a schematic diagram illustrating the first method of fatigue strength testing using the samples involved in the comparative example.

[0067] Figure 19C This is a schematic diagram illustrating the second method of fatigue strength testing using the samples involved in the comparative example.

[0068] Figure 20 It is a graph representing the results of a fatigue strength test. Detailed Implementation

[0069] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited in any way except for its essential structure.

[0070] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are illustrative of the present invention, and the present invention is not limited in any way except for its essential structure.

[0071] [First Embodiment]

[0072] 1. Simplified structure of laser welding device 1

[0073] Figure 1 This is a schematic diagram showing the configuration of the laser welding apparatus 1 according to the first embodiment.

[0074] like Figure 1 As shown, the laser welding apparatus 1 includes a laser oscillator 11, an optical path 12, and a focusing unit 13. The laser oscillator 11 generates laser LB according to instructions from a controller (control unit) 16 connected to the laser oscillator 11.

[0075] The laser LB generated by the laser oscillator 11 is propagated to the focusing unit 13 through the optical path 12. In the focusing unit 13, the propagated laser LB is focused onto the upper surface of the metal plate (first component) 501 (forming a light spot). Here, the focusing unit 13 has the function of focusing the laser LB (as a focusing unit) and also has the function of scanning the light spot on the upper surface of the metal plate 501 (as a scanning unit). The scanning of the light spot is also performed according to instructions from the controller 16.

[0076] The controller 16 is constructed by including a microprocessor consisting of a CPU, RAM, ROM, etc., and its peripheral circuitry.

[0077] Furthermore, in the laser welding apparatus 1 according to this embodiment, an optical cable is used as an example of optical path 12, but various other optical paths capable of propagating laser LB can also be used. In this embodiment, a T-joint is formed by joining metal plate 501 and metal plate (second member) 502.

[0078] The laser welding apparatus 1 includes a welding robot 14 and a driver 15 that drives the welding robot 14. The welding robot 14 has a focusing unit 13 mounted on its distal end, and the focusing unit 13 moves in three dimensions according to instructions from a controller 16 connected to the driver 15.

[0079] 2. Overview of Laser Welding Methods

[0080] Figure 2A This is a perspective view illustrating a method of joining sheet materials together using laser welding, showing the configuration steps in which the end face 502a of metal plate 502 is mated to the lower surface 501b of metal plate 501. Figure 2B This is a perspective view illustrating a method of joining sheet materials together using laser welding, showing the laser irradiation step of irradiating the upper surface 501a of the metal sheet 501 with laser LB. Figure 3 This is a top view showing the scanning trajectory LLB of the laser beam (LB) during laser welding.

[0081] (1) Configuration steps

[0082] First, prepare a metal plate 501 as the first component and a metal plate 502 as the second component. The thickness of the metal plate 501 is T501.

[0083] like Figure 2A As shown, the end face 502a of the metal plate 502 is aligned with the lower surface 501b of the metal plate 501. At this time, a slight gap can remain between the lower surface 501b of the metal plate 501 and the end face 502a of the metal plate 502. In other words, the end face 502a of the metal plate 502 can be brought close to the lower surface 501b of the metal plate 501.

[0084] (2) Laser irradiation steps

[0085] like Figure 2B As shown, while maintaining the state where the end face 502a of the metal plate 502 is aligned with the lower surface 501b of the metal plate 501, a designated area of ​​the upper surface 501a of the metal plate 501 is irradiated with laser LB. During the irradiation of laser LB, as... Figure 2B As indicated by the arrow, the laser LB spot is scanned in a circular pattern around the specified location. Specifically, as... Figure 3As shown, with position Ax503 on the upper surface 501a of the metal plate 501 as the center, the laser LB spot is made to perform a circular scan around the position Ax503 as the circular center, so that the scanning trajectory LLB becomes a vortex.

[0086] Here, as Figure 3 As shown, the area irradiated by laser LB (the designated area) is a portion of the upper surface 501a of metal plate 501 located on the opposite side of the area abutted by the end face 502a of metal plate 502 (the opposite side of the plate thickness T501 of metal plate 501) and its surrounding area. Furthermore, the outer diameter φL of the region where the laser spot of LB circulates is equal to or larger than the outer diameter of the region W502 corresponding to the plate thickness of metal plate 502.

[0087] By setting the outer diameter φL to be equal to or larger than the outer diameter of region W502 (equal to or larger than the thickness of metal plate 502), the portion where metal plate 501 and metal plate 502 are to be joined can be melted. In the case of forming a T-joint as in this embodiment, a fillet weld can be formed at the stress concentration location of the joint, and metal plate 501 and metal plate 502 can be joined with high strength.

[0088] 3. Morphology of welded part 503

[0089] Figure 4 This is a top view showing the welded portion 503 formed based on welding using the laser welding device 1. Figure 5 It means Figure 4 A cross-sectional view of the VV line section.

[0090] like Figure 4 As shown, after metal plate 501 and metal plate 502 are joined using the laser welding apparatus 1 according to this embodiment, a welded portion 503 that is approximately circular in plan view is formed. However, the plan view shape of the welded portion is not limited to approximately circular; it may also be oval.

[0091] like Figure 5 As shown, when viewing the metal plates 501, 502 and the welded portion 503 in cross-section, the upper surface (the side of the upper surface 501a of the metal plate 501) 503a of the roughly circular welded portion 503, when viewed from above, has a shape that is recessed to some extent relative to the periphery of the upper surface 501a of the metal plate 501.

[0092] Furthermore, in the generally circular weld portion 503 viewed from above, fillet weld portions 503b and 503c are provided on the lower surface 501b side of the metal plate 501 and near the butt joint portion of the metal plate 502. The fillet weld portions 503b and 503c are formed based on the inflow of molten metal generated during welding when the laser LB spot is circumferential, as shown in FIG. 2(b), without the need to supply filler materials such as wire to both sides of the butt joint portion. Therefore, in the laser welding method according to this embodiment, the metal plate 501 and the metal plate 502 can be joined with high strength.

[0093] 4. Setting the position of the circumferential center Ax503 of the laser LB spot.

[0094] Figure 6A This is a top view showing the positional relationship between the mating portions of metal plates 501 and 502 and the annular center Ax503 of the laser LB spot. Figure 6B This is a front view showing the positional relationship between the mating parts of metal plates 501 and 502 and the annular center Ax503 of the laser LB spot.

[0095] Figure 6B As shown, in the laser welding described in this embodiment, the end face 502a of the metal plate 502 is abutted against the lower surface 501b of the metal plate 501 to achieve contact (see reference). Figure 2A Therefore, the mating portion between metal plate 501 and metal plate 502 is the region W502, which is equivalent to the thickness of metal plate 502.

[0096] In the laser welding described in this embodiment, the annular center Ax503 of the laser LB spot is set within a region W502 on the upper surface 501a of the metal plate 501. Thus, as... Figure 6A As shown, a weld portion 503 with a center and approximately circular shape when viewed from above is formed in region W502 within the upper surface 501a of the metal plate 501.

[0097] As described above, based on the setting of the annular center Ax503, fillet weld portions 503b and 503c can be formed on both sides of the mating portion between the lower surface 501b of the metal plate 501 and the end face 502a of the metal plate 502 without the need to supply filler material or pre-process the peripheral portion of the welded portion, which has an advantage in terms of high-strength bonding of the metal plate 501 and the metal plate 502.

[0098] Furthermore, by using a laser to melt the two components 501 and 502 to be joined, fillet welds 503b and 503c are formed based on the effects of gravity and surface tension at the joint corners, which can further improve the strength.

[0099] [Second Embodiment]

[0100] Figure 7 This is a cross-sectional view of the welded portion 509, which is approximately circular in plan view and formed by the laser welding method according to the second embodiment.

[0101] In this embodiment, a laser welding apparatus with a structure substantially the same as that described in the first embodiment is used. The difference from the first embodiment is that there are three metal plates 506 to 508 to be joined.

[0102] like Figure 7 As shown, in the laser welding method of this embodiment, in the configuration step, metal plates 506 and 507 are stacked, and the end face of metal plate 508 abuts against or approaches the lower surface of metal plate 507. Furthermore, in this embodiment, a small gap G1 is spaced between metal plates 506 and 507. However, the gap G1 between metal plates 506 and 507 is not necessary.

[0103] Furthermore, in the laser welding method according to this embodiment, laser LB is used to irradiate the upper surface 506a of the metal plate 506 from above, thereby forming a weld portion 509 that is approximately circular when viewed from above. As a result, the metal plates 506, 507, and 508 are joined together.

[0104] Furthermore, in this embodiment, during the laser irradiation step, the laser LB spot is scanned in a circular manner around a designated position to form a weld portion 509 that is approximately circular or oval in shape when viewed from above, and fillet weld portions 509b and 509c are formed in the same manner as in the embodiment described above. Moreover, as... Figure 7 As shown, the upper surface 509a of the roughly circular welded portion 509, when viewed from above, is recessed to a certain extent relative to the upper surface 506a of the metal plate 506.

[0105] In the laser welding method described in this embodiment, although welding is performed on two overlapping metal plates 506 and 507, a high-strength bond can be achieved in the same way as in the first embodiment described above.

[0106] In the technology disclosed in Patent Document 2 above, a laser is irradiated from the top of a metal plate, and the laser spot is laterally oscillated on the upper surface (scanning in a zigzag pattern, a curved pattern, a wave pattern, or a spiral pattern). With this method, the following problems may arise: the configuration of weldable metal components is limited, and sometimes sufficient joint strength cannot be obtained based on the configuration.

[0107] Furthermore, as shown in (iii) above, in the prior art, in such Figure 7 When multiple metal plates are stacked and welded as shown, the following problem arises: even if each component is within tolerance, deviations caused by their precision errors will result in a smaller target position margin.

[0108] In addition, in order to form Figure 7 In the case of joints with the shape shown, beveling accuracy is required, and the workpiece clearance margin is less than 0.2. Therefore, the shear surface or fracture surface generated by stamping will affect the joint strength.

[0109] Furthermore, when there are gaps between workpieces, there are also problems such as undercutting or the inability to overlap multiple metal plates to form a joint.

[0110] In this regard, if the laser welding method described in this embodiment is adopted, the above-mentioned problems can be solved, and metal components can be welded with a relatively high degree of freedom.

[0111] [Third Implementation]

[0112] Figure 8 This is a perspective view (partial cross-sectional view) of the welded portion 513, which is formed by the laser welding method according to the third embodiment, and is approximately semi-circular from top view.

[0113] In this embodiment, a laser welding apparatus with a structure substantially the same as that described in the first embodiment is used. The difference from the first embodiment lies in the arrangement of the metal plate 512 relative to the metal plate 511 and the formation position of the welding portion 513.

[0114] like Figure 8 As shown, in the laser welding according to this embodiment, a corner joint is formed using two metal plates (first component and second component) 511 and 512. Specifically, the end face of the metal plate 512 is brought into contact with or close to the end of the lower surface (one main surface) 511b of the metal plate 511. Furthermore, laser LB is irradiated onto the upper surface (the other main surface) 511a of the metal plate 511. Moreover, similar to the first embodiment described above, the spot of laser LB is made to circulate around a designated position on the upper surface 511a of the metal plate 511. As a result, a weld portion 513 that is approximately semi-circular when viewed from above is formed.

[0115] In addition, a fillet weld portion 513b is formed at the portion of the metal plate 512 that abuts against the lower surface 511b of the metal plate 511.

[0116] The definition of the area involved in the ring of the laser LB spot is the same as in the first embodiment described above. However, when forming the corner joint, the scanning trajectory is controlled in a way that the outer side of the upper surface 511a of the metal plate 511 is not irradiated by the laser LB.

[0117] Even when forming a corner joint using the laser welding method described above, the metal plate 511 and the metal plate 512 can be joined with high strength with a large positional margin, just like in the first embodiment described above.

[0118] [Fourth Embodiment]

[0119] Figure 9 This is a perspective view (partial cross-sectional view) of the welded portion 518, which is formed by the laser welding method according to the fourth embodiment and is approximately circular from top view.

[0120] In this embodiment, a laser welding apparatus with a structure substantially the same as that described in the first embodiment is used. The difference from the first embodiment is that an L-shaped metal plate 517 is used as a second component.

[0121] like Figure 9 As shown, in the laser welding according to this embodiment, a flared joint is formed using two metal plates (first component and second component) 516 and 517. Specifically, a portion of the metal plate 517, which has an L-shaped cross-section, abuts against the lower surface (one main surface) 516b of the metal plate 516. Furthermore, a laser LB is irradiated onto the upper surface (the other main surface) 516a of the metal plate 516. In this embodiment, similar to the first embodiment described above, the laser spot of the LB is made to circulate around a designated position on the upper surface 516a of the metal plate 516. This forms a weld portion 518 that is approximately circular when viewed from above.

[0122] Furthermore, a fillet weld portion 518b is formed near the gap portion where the lower surfaces 516b of the metal plate 517 and the metal plate 516 abut.

[0123] Here, the area of ​​the upper surface 516a irradiated by the laser LB is the area on the opposite side of the position of the bend 517a of the metal plate 517, separated by the thickness of the metal plate 516 when viewed from above, and its surrounding area. The definition of the area involved in the annularity of the laser LB spot is the same as in the first embodiment described above.

[0124] Even when forming a corner joint using the laser welding method described above, the metal plate 516 and the metal plate 517 can be joined with high strength with a large positional margin, just like in the first embodiment described above.

[0125] [Fifth Embodiment]

[0126] Figure 10 This is a perspective view (partial cross-sectional view) of the welded portion 523, which is formed by the laser welding method according to the fifth embodiment and is approximately circular from a top view. Figure 11A This is a top view showing the positional relationship between the metal plate 521 and the pipe 522 and the center (circumferential center of the laser LB spot) Ax523 of the welded part 523. Figure 11B This is a front view showing the positional relationship between the metal plate 521 and the pipe 522 and the center (circumferential center of the laser LB spot) Ax523 of the welded part 523.

[0127] 1. Laser welding method

[0128] like Figure 10 As shown, in the laser welding according to this embodiment, a metal plate (first component) 521 is joined to a pipe 522. Specifically, the outer peripheral surface of the pipe 522 is partially brought into contact with or close to the lower surface (one main surface) 521b of the metal plate 521. Furthermore, a laser LB is irradiated onto the upper surface (another main surface) 521a of the metal plate 521. Moreover, in this embodiment, similar to the first embodiment described above, the laser spot of the LB is made to circumferentially surround a designated position on the upper surface 521a of the metal plate 521. As a result, a weld portion 523 that is approximately circular when viewed from above is formed.

[0129] In addition, fillet weld portions 523b and 523c are formed on both sides of the position where the pipe 522 abuts or approaches the lower surface 521b of the metal plate 521.

[0130] Here, the area of ​​the upper surface 521a irradiated by the laser LB is the position on the opposite side of the metal plate 521 that is abutted or approached by the outer peripheral surface of the tube 522 when viewed from above, and the surrounding area thereof. The definition of the area involved in the annularity of the laser LB spot is the same as in the first embodiment described above.

[0131] Even when forming a corner joint using the laser welding method described above, the metal plate 521 and the pipe 522 can be joined with high strength with a large positional margin, just like in the first embodiment described above.

[0132] 2. The annular center Ax523 of the laser LB spot.

[0133] like Figure 11A and Figure 11BAs shown, in the laser welding method of this embodiment, the position where the lower surface (one main surface) 521b of the metal plate 521 abuts or is closest to the outer peripheral surface 522a of the tube 522 is set as the annular center Ax523 of the laser LB spot. Therefore, when using the laser welding method of this embodiment, a welded portion 523 that is approximately circular in plan view with the annular center Ax523 as the center is formed.

[0134] However, the annular center Ax523 of the laser LB spot can be set in the range Ar522. Specifically, the range Ar522 is set as follows.

[0135] like Figure 11B As shown, a portion of the outer peripheral surface 522a of the pipe 522 is brought into contact with or close to the lower surface 521b of the metal plate 521. At this time, a virtual line L0 is drawn below the metal plate 521, with a gap G2 relative to the lower surface 521b of the metal plate 521. Furthermore, the intersection points of the virtual line L0 and the outer peripheral surface 522a of the pipe 522 are set as positions P1 and P2.

[0136] Here, the gap G2 is equal to or less than 1 / 2 of the thickness T521 of the metal plate 521.

[0137] Draw virtual lines L1 and L2, orthogonal to the upper surface 521a of the metal plate 521, from positions P1 and P2 respectively. In this case, the area between virtual lines L1 and L2 is set as range Ar522.

[0138] The range Ar522 is set as described above for the following reasons.

[0139] The inventors of this invention have discovered that when the gap G2 is greater than half the thickness T521 of the metal plate 521, problems such as decreased shear force or burn-through occur as the gap G2 increases. The inventors conducted in-depth research on this problem and concluded that: because the gap G2 is greater than (T521 / 2), the bending stress acting on the weld 523 increases, and the amount of molten metal flowing into the gap G2 increases, leading to a decrease in plate thickness at areas of uneven thickness or stress concentration, which is the cause of decreased strength. Therefore, the following conclusion is drawn: to reliably ensure welding quality, the gap G2 must be controlled to be equal to or less than half the thickness T521 of the metal plate 521.

[0140] In addition, after conducting experiments on the relationship between the gap (GAP) and tensile shear force when laser welding two metal plates, the following results were obtained: the strength increases slightly up to 20% of the plate thickness, the increase decreases at 30%, it is equivalent to GAP being "0" at 50%, and decreases by 17% at 70%.

[0141] Furthermore, in this embodiment, when welding the metal plate 521 and the pipe 522, the range Ar522 is specified as described above. However, the component as the second component is not limited to the pipe 522, and various components such as metal plates and wires are also included.

[0142] [Sixth Implementation]

[0143] Figure 12 This is a perspective view (partial cross-sectional view) of the welded portion 528, which is formed by the laser welding method according to the sixth embodiment and is approximately circular from a top view.

[0144] In this embodiment, a laser welding apparatus with a structure substantially the same as that described in the first embodiment is used. The difference from the first embodiment is that wire 527 is used as a second component.

[0145] like Figure 12 As shown, in the laser welding according to this embodiment, a wire (second component) 527 is joined to the lower surface (one main surface) 526b of a metal plate (first component) 526. Specifically, the end face of the wire 527 is brought into contact with or close to the lower surface 526b of the metal plate 526. Furthermore, a laser LB is irradiated onto the upper surface (another main surface) 526a of the metal plate 526. Moreover, in this embodiment, similar to the first embodiment described above, the laser spot of the LB is made to circumferentially surround a designated position on the upper surface 526a of the metal plate 526. As a result, a weld portion 528 that is approximately circular when viewed from above is formed.

[0146] In addition, fillet weld portions 528b and 528c are formed on both sides of the portion of the wire 527 that abuts or approaches the lower surface 526b of the metal plate 526.

[0147] Here, the area of ​​the upper surface 526a irradiated by the laser LB is the position on the opposite side of the metal plate 526 that is abutted or close to the end face of the wire 527 when viewed from above, and its surrounding area. The definition of the area involved in the annularity of the laser LB spot is the same as in the first embodiment described above.

[0148] Even when joining using the laser welding method described above, the metal plate 526 and the wire 527 can be joined with high strength with a large positional margin, just like in the first embodiment described above.

[0149] [Seventh Embodiment]

[0150] Figure 13 This is a perspective view used to illustrate the laser welding method according to the seventh embodiment.

[0151] In this embodiment, a laser welding apparatus with a structure substantially the same as that described in the first embodiment is used. The difference from the first embodiment lies in the arrangement of the metal plates 531 and 532, and the supply line (filler material) 533.

[0152] like Figure 13 As shown, in the laser welding involved in this embodiment, similarly to the first embodiment described above, two metal plates (first component and second component) 531 and 532 are used to form a T-joint. Specifically, the end face 532a of the metal plate 532 is brought close to the lower surface (one main surface) 531b of the metal plate 531. Here, in this embodiment, the gap G3 between the lower surface 531b of the metal plate 531 and the end face 532a of the metal plate 532 is equal to or greater than 1 / 2 of the plate thickness T531 of the metal plate 531.

[0153] Furthermore, in the laser welding method according to this embodiment, laser LB is irradiated on the upper surface (another main surface) 531a of the metal plate 531 while the wire (filler material) 533 is supplied to the irradiation range. In addition, similar to the first embodiment described above, a weld portion with a generally circular shape when viewed from above is formed by making the laser LB spot circulate around a designated position on the upper surface 531a of the metal plate 531.

[0154] Even when forming a corner joint using the laser welding method described above, the metal plate 531 and the metal plate 532 can be joined with high strength with a large positional margin, just like in the first embodiment described above.

[0155] Here, when laser welding is performed with metal plates 531 and 532 arranged with a gap G3 equal to or greater than 1 / 2 of the plate thickness T531, problems such as reduced strength or burn-through may occur if the wire 533 is not supplied. However, if the wire 533 is supplied during laser welding as in this embodiment, the metal deficiency caused by the gap G3 can be compensated by the supply of the wire 533 (due to insufficient metal flowing into the gap G3), thus suppressing the occurrence of problems such as insufficient strength or burn-through.

[0156] Furthermore, while no specific mention has been made of devices related to the supply of the welding wire 533 above, as long as a wire supply machine (filler material supply machine) is provided to supply the welding wire 533 to the head or other positions of the welding robot 14 as needed, it is possible to achieve the following: Figure 13 The supply of filler material shall be performed as shown.

[0157] [Eighth Embodiment]

[0158] Figure 14A This is a top view showing the generally circular welded portion 538 formed by the laser welding method according to the eighth embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0159] like Figure 14A As shown, in the laser welding method of this embodiment, the end face of the metal plate 537 abuts against or approaches a main face of the metal plate 536 (relative to the end face of the metal plate 536). Figure 14A The paper surface is located on the opposite side of the front main surface. Furthermore, on the other main surface of metal plate 536 ( Figure 14A The paper surface and the front main surface form multiple roughly circular welded parts 538 when viewed from above.

[0160] Multiple welded portions 538 are formed in an overlapping manner and are arranged in a direction extending along the end face of the metal plate 537.

[0161] If the laser welding method described above is used, not only can the same effect as the first embodiment described above be obtained, but it also has advantages, for example, when performing welding that requires gas sealing.

[0162] [Ninth Embodiment]

[0163] Figure 14B This is a top view showing the generally circular welded portion 541 formed by the laser welding method according to the ninth embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0164] like Figure 14B As shown, in the laser welding method of this embodiment, the end face of the metal plate 540 abuts against or approaches a main face of the metal plate 539 (relative to the end face of the metal plate 539). Figure 14B The paper surface is located on the opposite side of the front main surface. Furthermore, on another main surface of metal plate 539 ( Figure 14B The paper surface and the front main surface form multiple roughly circular welded parts 541 when viewed from above.

[0165] Multiple welded portions 541 are arranged in a direction extending along the end face of the metal plate 540 in a state of mutual separation and spacing.

[0166] Even when using the laser welding method described above, the same effect as in the eighth embodiment described above can be obtained.

[0167] [Embodiment 10]

[0168] Figure 14C This is a top view showing the generally circular welded portion 544 formed by the laser welding method according to the 10th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the 1st embodiment described above is used.

[0169] like Figure 14C As shown, in the laser welding method of this embodiment, the end face of the metal plate 543 is brought into contact with or near a main face of the metal plate 542 (relative to the end face of the metal plate 542). Figure 14C The paper surface is located on the opposite side of the front main surface. Furthermore, on the other main surface of metal plate 542 ( Figure 14C The paper surface and the front main surface form multiple roughly circular welded parts 544 when viewed from above.

[0170] Multiple welded portions 544 are arranged in two side-by-side columns, and the configuration of each column is the same as in the eighth embodiment described above. Furthermore, the columns are arranged at intervals between each other.

[0171] If the laser welding method described above is used, not only can the same effect as the first embodiment be obtained, but it also has advantages, for example, when performing welding that requires higher gas sealing performance than the laser welding method of the eighth embodiment.

[0172] [11th Embodiment]

[0173] Figure 14D This is a top view showing the generally circular welded portion 547 formed by the laser welding method according to the 11th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0174] like Figure 14D As shown, in the laser welding method of this embodiment, the end face of the metal plate 546 abuts against or approaches a main face of the metal plate 545 (relative to the end face of the metal plate 545). Figure 14D The paper surface is located on the opposite side of the front main surface. Furthermore, on the other main surface of metal plate 545 ( Figure 14D The paper surface and the front main surface form multiple roughly circular welded parts 547 when viewed from above.

[0175] Multiple welded portions 547 form the same columns as in the ninth embodiment described above, and each column is arranged side by side at intervals.

[0176] If the laser welding method described above is used, not only can the same effect as the first embodiment be obtained, but it also has advantages, for example, when performing welding that requires higher gas sealing performance than the laser welding method of the ninth embodiment.

[0177] [12th Embodiment]

[0178] Figure 14E This is a top view showing the generally circular welded portion 550 formed by the laser welding method according to the 12th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the 1st embodiment described above is used.

[0179] like Figure 14E As shown, in the laser welding method of this embodiment, the end face of the metal plate 549 is brought into contact with or near a main face of the metal plate 548 (relative to the end face of the metal plate 548). Figure 14E The paper surface is located on the opposite side of the front main surface. Furthermore, on the other main surface of metal plate 548 ( Figure 14E The paper surface and the front main surface form multiple roughly circular welded parts 550 when viewed from above.

[0180] Multiple welded parts 550 are formed in an overlapping manner and are arranged in a serrated manner when viewed from above.

[0181] Even using the laser welding method described above, the same effect as in the eighth embodiment described above can be obtained.

[0182] [13th Embodiment]

[0183] Figure 14F This is a top view showing the generally circular welded portion 553 formed by the laser welding method according to the 13th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the 1st embodiment described above is used.

[0184] like Figure 14F As shown, in the laser welding method of this embodiment, the end face of the metal plate 552 is brought into contact with or close to a main face of the metal plate 551 (relative to the end face of the metal plate 552). Figure 14F The paper surface is located on the opposite side of the front main surface. Furthermore, on the other main surface of metal plate 551 ( Figure 14F The paper surface and the front main surface form multiple roughly circular welded parts 553 when viewed from above.

[0185] Multiple welded portions 553 are formed in a spaced-apart manner and are arranged in a serrated manner when viewed from above.

[0186] Even using the laser welding method described above, the same effect as in the ninth embodiment described above can be obtained.

[0187] [14th Embodiment]

[0188] Figure 15A This is a perspective view (partial cross-sectional view) showing the welded portion (generally circular welded portion 556 and linear welded portion 557 in plan view) formed by the laser welding method according to the 14th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the 1st embodiment described above is used.

[0189] like Figure 15A As shown, in the laser welding method of this embodiment, a portion of the outer peripheral surface of the tube 555 is arranged to abut or approach the lower surface (one main surface) 554b of the metal plate 554. Furthermore, a laser LB is irradiated onto the upper surface (another main surface) 554a of the metal plate 554 to form a plurality of weld portions 556 that are approximately circular in plan view and linear weld portions 557 that are linear in plan view.

[0190] In addition, fillet weld portions 556b and 556c are formed on both sides of the portion where the pipe 555 abuts or approaches the lower surface 554b of the metal plate 554.

[0191] In the laser welding method described in this embodiment, the weld portion 556 and the linear weld portion 557 can be formed continuously, or multiple weld portions 556 can be formed first, and then the linear weld portion 557 can be formed by connecting the weld portions 556 to each other. Furthermore, continuous formation means continuously forming the weld portion 556 and the linear weld portion 557, which are approximately circular in top view, by performing laser LB spot scanning while maintaining laser oscillation.

[0192] Even using the laser welding method described above, the same effect as in the eighth embodiment can be achieved, and it has advantages in ensuring higher gas-tightness.

[0193] [15th Embodiment]

[0194] Figure 15B This is a top view showing the welded portion (generally circular welded portion 560 and linear welded portion 561) formed by the laser welding method according to the 15th embodiment. Figure 15CThis is a cross-sectional view showing the welded portion (generally circular welded portion 560 from top view and linear welded portion 561 from top view) formed by the laser welding method according to the 15th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0195] like Figure 15B As shown, in the laser welding method of this embodiment, a portion of the outer peripheral surface of the tube 559 is arranged to abut or approach the lower surface (one main surface) 558b of the metal plate 558. Furthermore, laser LB is irradiated onto the upper surface (another main surface) 558a of the metal plate 558 to form two weld portions 560 and one linear weld portion 561. The two weld portions 560 are spaced apart from each other radially from the tube 559, and the linear weld portion 561 is formed to extend radially along the tube 559.

[0196] In addition, fillet weld portions 560b and 560c are formed on both sides of the portion where the pipe 559 abuts or approaches the lower surface 558b of the metal plate 558.

[0197] In the laser welding method of this embodiment, a welding portion 560 that is approximately circular when viewed from above and a linear welding portion 561 can be formed continuously, or two welding portions 560 can be formed first, and then the linear welding portion 561 can be formed by connecting the welding portions 560 to each other.

[0198] Even when using the laser welding method described above, the same effect as in the fifth embodiment described above can be obtained, and the following effect can also be obtained.

[0199] In the laser welding method of this embodiment, for example, when it is desirable to give width in order to obtain a fillet weld effect, considering that the stress applied to the radial center of the tube 559 is smaller than that at the end in terms of stress distribution when peeling or shearing load is applied, the operation steps can be shortened by connecting this part with a linear welding part 561.

[0200] [Sixth Embodiment]

[0201] Figure 16A This is a perspective view showing the approximately circular welded portion 564 formed by the laser welding method according to the 16th embodiment, viewed from above. Figure 16B This is a cross-sectional view showing the generally circular welded portion 564 formed by the laser welding method according to the 16th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0202] like Figure 16Aand Figure 16B As shown, in the laser welding method of this embodiment, a portion of the outer peripheral surface of the circular cross-section wire (second member) 563 is arranged to abut or approach the lower surface (one main surface) 562b of the metal plate 562. Furthermore, laser LB is irradiated onto the upper surface (another main surface) 562a of the metal plate 562 to form a plurality of weld portions 564 that are approximately circular in plan view. The plurality of weld portions 564 are formed in a state of being spaced apart from each other in the direction in which the wire 563 extends.

[0203] In addition, fillet weld portions 564b and 564c are formed on both sides of the portion where the wire 563 abuts or approaches the lower surface 562b of the metal plate 562.

[0204] Even with the laser welding method described above, the circular cross-section wire 563 can be joined to the metal plate 562 with a large positional margin and high strength.

[0205] [17th Embodiment]

[0206] Figure 16C This is a perspective view showing the welded portion (generally circular welded portion 567 from top view and linear welded portion 568 from top view) formed by the laser welding method according to the 17th embodiment. Figure 16D This is a cross-sectional view showing the welded portion (generally circular welded portion 567 and linear welded portion 568 in plan view) formed by the laser welding method according to the 17th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0207] like Figure 16C and Figure 16D As shown, in the laser welding method of this embodiment, a metal plate 566 having an L-shaped cross-section is partially contacted with the lower surface (one main surface) 565b of a metal plate 565. Furthermore, a laser LB is irradiated onto the upper surface (another main surface) 565a of the metal plate 565 to form three weld portions 567 and two linear weld portions 568. The three weld portions 567 are spaced apart from each other, and the linear weld portions 568 are formed in a manner that connects the weld portions 567 to each other.

[0208] In the laser welding method of this embodiment, the welding part 567 and the linear welding part 568 can be formed by a continuous process, or three welding parts 567 can be formed first, and then the linear welding part 568 can be formed by connecting the welding parts 567 to each other.

[0209] Furthermore, a fillet weld portion 567b is formed near the portion where the lower surfaces 565b of the metal plate 566 and the metal plate 565 abut.

[0210] The laser welding method described above can achieve the same effect as the fourth embodiment described above, and has advantages when performing welding that requires higher gas sealing performance.

[0211] [Embodiment 18]

[0212] Figure 17 This is a perspective view (partial cross-sectional view) showing the generally circular welded portion 571 formed by the laser welding method according to the 18th embodiment. In this embodiment, a laser welding apparatus with a structure substantially the same as that of the laser welding apparatus 1 according to the first embodiment described above is used.

[0213] like Figure 17 As shown, in the laser welding according to this embodiment, two metal plates (first component and second component) 569 and 570 are used to form a lap joint. Specifically, metal plate 570 is overlapped with the lower surface (one main surface) 569b of metal plate 569. Furthermore, metal plates 569 and 570 can be overlapped without gaps or with gaps between them. Next, laser LB is irradiated onto the upper surface (the other main surface) 569a of metal plate 569 to form a weld portion 571 that is approximately circular in plan view. Furthermore, in this embodiment, similar to the first to the 17th embodiments described above, the laser spot of LB is made to circulate around a designated position on the upper surface 569a of metal plate 569. This forms a weld portion 571 that is approximately circular in plan view.

[0214] Furthermore, a fillet weld portion 571b is formed at the end of the portion where the lower surfaces 569b of the metal plate 570 and the metal plate 569 overlap.

[0215] Even when forming a corner joint using the laser welding method described above, the metal plate 569 and the metal plate 570 can be joined with high strength with a large positional margin, just like in the first embodiment described above.

[0216] [Results Confirmed]

[0217] (1) Shape deformation (angular deformation) based on thermal deformation

[0218] (i) Examples and Comparative Examples

[0219] Figure 18A This is a perspective view illustrating the laser welding method involved in the embodiment. Figure 18B This is a perspective view showing the laser welding method involved in the comparative example.

[0220] First, such as Figure 18A and Figure 18BAs shown, a hot-rolled steel plate (SPFH590) of 40mm×100mm×3.2mm was prepared. Furthermore, the end face of the steel plate 573 was arranged to abut against the lower surface 572b of the steel plate 572.

[0221] • Example

[0222] like Figure 18A As shown, in the laser welding method described in this embodiment, a laser LB is irradiated onto the upper surface 572a of the steel plate 572, and five weld portions 574, which are approximately elliptical in shape when viewed from above, are formed by scanning in a manner that causes the laser spot of the LB to circulate around a designated position. As shown in the portion surrounded by the double-dotted line, each weld portion 574 has a planar shape with a major axis of 7 mm and a minor axis of 3.5 mm, and a total weld portion of 35 mm is formed based on the five weld portions 574.

[0223] In addition, the laser welding conditions are 3500W and 250mm / s.

[0224] Comparative examples

[0225] like Figure 18B As shown, in the laser welding method of the comparative example, laser LB is irradiated from the side where the lower surfaces 572b of steel plate 573 and steel plate 572 are joined, and the laser spot of laser LB is scanned along the end edge of the steel plates 573 involved in the joining. As a result, a linear weld portion 974 is formed along the end edge of the steel plate 573. The length of the weld portion 974 is 35 mm.

[0226] In addition, the laser welding conditions are 3500W and 50mm / s.

[0227] (ii) Shape deformation (angular deformation)

[0228] Figure 18C This is a cross-sectional view showing the shape deformation state of the steel plate 572 on the T-joint formed by the laser welding method involved in the embodiment. Figure 18D This is a cross-sectional view showing the shape deformation state of the steel plate 572 on the T-joint formed by the laser welding method involved in the comparative example.

[0229] First, such as Figure 18C As shown, in the laser welding method described in the embodiment, the steel plate 572 is deformed by an angle θ1. The angle θ1 is approximately 0.1°.

[0230] Secondly, such as Figure 18D As shown, in the laser welding method involved in the comparative example, the steel plate 572 was deformed by an angle θ2. The angle θ2 is approximately 0.5°.

[0231] As described above, when using the laser welding method described in the embodiments, compared to the case of using the laser welding method described in the comparative examples which are similar to conventional techniques, the angular deformation (strain) can be reduced to approximately 1 / 5. Therefore, in the laser welding method described in the embodiments, a high-strength and low-strain joint can be achieved.

[0232] (2) Fatigue strength

[0233] (i) Test methods

[0234] Figure 19A This is a schematic diagram illustrating the method for fatigue strength testing of the samples involved in the embodiments. Figure 19B This is a schematic diagram illustrating the first method (the method of Comparative Example 1) used in the fatigue strength test of the sample involved in the comparative example. Figure 19C This is a schematic diagram illustrating the second method (the method of Comparative Example 2) for fatigue strength testing of the sample involved in the comparative example.

[0235] • Example

[0236] like Figure 19A As shown, a sample of the T-joint involved in the above embodiment is prepared, and the steel plate 572 is fixed. Furthermore, a load P of 100N-800N is repeatedly applied to a position 40mm away from the lower surface 572b of the steel plate 573 until it breaks.

[0237] • Compare the methods in Example 1

[0238] like Figure 19B As shown, a sample of the T-joint involved in the comparative example above was prepared, and the steel plate 572 was fixed. Furthermore, for the main surface 573a of the steel plate 573 that was irradiated by laser LB when forming the weld portion 974, a load P of 100N-800N was repeatedly applied at a position 40mm away from the lower surface 572b of the steel plate 572 until it broke, just as in the above embodiment.

[0239] • Compare the methods in Example 2

[0240] like Figure 19C As shown, a sample of the T-joint involved in the comparative example above was prepared, and the steel plate 572 was fixed. Furthermore, for the main surface 573b opposite to the side of the steel plate 573 that was irradiated by laser LB when forming the weld portion 974, a load P of 100N-800N was repeatedly applied at a position 40mm away from the lower surface 572b of the steel plate 572 until it broke, just as in the above embodiment.

[0241] (ii) Fatigue strength test results

[0242] Figure 20 It is a graph representing the results of a fatigue strength test.

[0243] like Figure 20 As shown, in this embodiment, the number of loops exceeded 140,000. In contrast, in Comparative Example 1, the number of loops did not reach 30,000, and in Comparative Example 2, the number of loops did not reach 20,000.

[0244] As described above, it is known that the embodiment has 4 to 5 times the fatigue strength compared to Comparative Example 1, and 7 times or more the fatigue strength compared to Comparative Example 2.

[0245] Furthermore, if the laser welding method involved in the previous technology is used to form fillet welds on the two main surfaces 573a and 573b of the steel plate 573, it may improve the fatigue strength to a certain extent. However, if fillet welds are to be formed on the two main surfaces 573a and 573b, multiple passes or multiple laser heads must be prepared during the laser LB irradiation, which inevitably leads to a decrease in productivity.

[0246] Furthermore, in the T-joint formed by the laser welding method described in the embodiments, similarly to the first to 18 embodiments described above, the fillet weld portion becomes an inwardly concave curved surface (R-surface). Therefore, stress concentration is unlikely to occur, and no additional processing steps (such as shot peening or grinding) or additional steps before or after these steps are required to reduce stress concentration. Therefore, it also has advantages in ensuring high productivity.

[0247] [Variation Example]

[0248] In the first, third, to 18th embodiments described above, laser welding was used to join two components. In the second embodiment described above, laser welding was used to join three components. However, the present invention is not limited to these methods. For example, the laser welding method described above can also be used to join one metal plate (first component) to three or more second components.

[0249] In the first to the 18th embodiments described above, weld portions 503, 509, 513, 518, 523, 528, 538, 541, 544, 547, 550, 553, 556, 560, 564, 567, and 571 are formed in a generally circular shape when viewed from above. In the above embodiments, weld portion 574 is formed in a generally elliptical shape when viewed from above. However, the present invention is not limited to this. For example, it may also form an oval weld portion when viewed from above or a polygonal shape (polygonal shape with rounded corners) when viewed from above.

[0250] In the first to 18th embodiments described above, the focusing section 13 is controlled to scan the spot of the laser LB; however, the present invention is not limited to this. For example, the spot of the laser LB can be scanned by driving and controlling the distal part of the welding robot 14, or by using an XY stage or the like.

[0251] Furthermore, in the first to 18th embodiments described above, the laser LB spot is moved during welding; however, the present invention is not limited to this. For example, the first and second components on the welding side can be moved to make the laser LB spot scan relative to each other.

[0252] Furthermore, the present invention can also perform laser welding by any combination of the first to the 18th embodiments described above.

[0253] [Summarize]

[0254] One aspect of the present invention relates to a laser welding method for joining a plate-shaped first component made of metallic material to a second component made of metallic material by laser welding, comprising: a configuration step in which the second component abuts against or approaches a main surface of the first component; and a laser irradiation step in which a laser is irradiated onto a main surface opposite to the main surface of the first component that the second component abuts against or approaches, i.e., another main surface of the first component; wherein, in the laser irradiation step, the first component and the second component are melted to form a weld portion that is generally circular or oval in plan view and a fillet weld portion is formed at the joint of the first component and the second component.

[0255] In the laser welding method involved in the above scheme, by irradiating the main surface opposite to the main surface of the first component that the second component abuts or approaches with a laser, that is, the other main surface of the first component, it is possible to avoid irradiating the side with a complex shape with a laser. It is not necessary to use multiple passes or multiple laser heads to achieve a complex shape. It is not necessary to add special devices or processes for the laser to reach the position. It is not necessary to restrict the irradiation direction, etc., and the problems of (v), (viii), and (ix) mentioned above can be solved.

[0256] Furthermore, in the laser welding method described above, the formation of a roughly circular or oval-shaped weld portion from a top view, along with a large weld portion width, increases the margin for positional deviation relative to the laser or the welded component. Since laser irradiation is performed within this weld portion, burn-through control is not difficult due to the increased heat input as the weld progresses into the latter half. Moreover, the large weld portion width and deep penetration prevent heat concentration, resulting in a molten pool that symmetrically approximates both sides of the welded component, further suppressing angular deformation (strain). Additionally, the increased molten metal volume due to the larger melt width and depth allows a portion of the molten metal to flow into the joint without the need for filler material or additional fillet weld shaping, utilizing surface tension to form an inwardly concave curved surface (R-shape) without additional treatment, resulting in a fillet weld portion where stress concentration is unlikely. Furthermore, since a portion of the added molten metal flows into the gaps between workpieces caused by low bevel precision due to the shearing or fracture surfaces of the stamping or by the precision error resulting from multiple overlapping pieces, sufficient bonding strength can be ensured, thus solving the problems mentioned above (i) to (iv), (vi), and (vii).

[0257] As described above, the laser welding method described in the above solution can solve the problems mentioned in (i) to (ix). Therefore, in the laser welding method described in the above solution, when welding metal components of various shapes to metal plates, it is possible to form fillet welds with a large positional margin, and even in the case of complex joint configurations, fillet welds can be formed without the need to add filler material, and joints can be performed with high productivity and high strength.

[0258] In the laser welding method involved in the above scheme, the following range can be projected onto the other main surface of the first component, and the projected range is set as the area irradiated by the laser, i.e., the designated area. The range is the range of the first component's main surface that the second component abuts against or approaches, and the gap between the main surface and the surface of the second component is equal to or less than 1 / 2 of the plate thickness of the first component.

[0259] As described above, by setting the area to be irradiated by the laser, i.e., the designated area, within the projected range, a sufficiently large fillet weld can be formed at the joint between the first and second components without adding filler material or additionally adding a shape to the components to form a fillet weld. Therefore, this method offers an advantage in achieving a stronger bond between the first and second components.

[0260] In the laser welding method described above, during the laser irradiation step, the laser spot can be made to scan circumferentially around a designated position with a center in the designated area of ​​the first component, with a diameter larger than the diameter of the laser spot.

[0261] As described above, when the weld portion and fillet weld portion are formed by scanning the laser spot around a designated position, since the weld portion is formed by melting and stirring the first and second components, even if there is a gap between the first and second components, molten metal can flow into the gap, resulting in a higher bonding strength.

[0262] In the laser welding method described above, when the gap between the first component and the surface of the second component is equal to or greater than 1 / 2 the thickness of the first component, the width of the second component can be projected onto the other main surface of the first component. The projected area is set as the area to be irradiated by the laser, i.e., the designated area. In the laser irradiation step, the laser spot is circumferentially scanned around a designated position with a center in the designated area of ​​the first component in a manner with a diameter greater than the diameter of the laser spot, and filling material is supplied to the irradiation range of the laser.

[0263] As described above, when the gap is equal to or greater than half the thickness of the first member, supplying filler material within the laser irradiation range can suppress problems such as decreased joint strength and burn-through. Therefore, by employing the above solution, even when the gap is equal to or greater than half the thickness of the first member, the first member and the second member can be joined with high strength.

[0264] In the laser welding method described above, multiple welded portions can be formed.

[0265] As described above, by forming multiple welded sections, it is possible to suppress problems such as burn-through caused by excessive heat input in the latter half of the weld and at the ends, and to join the first component and the second component with high strength.

[0266] In the laser welding method described above, after forming multiple weld portions at intervals from each other in the laser irradiation step, a linear weld portion that appears as a line when viewed from above can be formed by connecting adjacent weld portions to each other.

[0267] As described above, when a linear weld is formed by connecting adjacent welds to each other, airtightness can be ensured and working time can be reduced in locations with low stress.

[0268] In the laser welding method described above, during the laser irradiation step, when multiple weld portions are formed apart from each other, a linear weld portion that appears as a line when viewed from above can be continuously formed by connecting adjacent weld portions to each other.

[0269] As described above, when a linear weld portion is continuously formed in the case of forming multiple weld portions (weld portions formed by scanning the spot in a circular motion), the same as when a linear weld portion is formed after forming multiple weld portions, it is possible to ensure gas sealing and reduce working time at low stress locations.

[0270] One aspect of the present invention relates to a laser welding apparatus for joining a plate-shaped first component made of a metallic material to a second component made of a metallic material by laser welding, comprising: a laser oscillator for generating a laser; a focusing section for focusing the laser; a scanning section for scanning the laser spot; and a control section for controlling the laser oscillator and the scanning section; wherein the control section, with the second component abutting or approaching one main surface of the first component, irradiates the laser onto the main surface opposite to the one main surface of the first component that the second component abuts or approaches, i.e., the other main surface of the first component, thereby melting the first component and the second component by irradiating them with the laser to form a weld portion that is generally circular or oval in shape when viewed from above, and forming a fillet weld portion at the joint of the first component and the second component.

[0271] In the laser welding apparatus involved in the above scheme, by irradiating the main surface opposite to the main surface of the first component that the second component abuts or approaches with a laser, i.e., the other main surface of the first component, it is possible to avoid irradiating the side with a complex shape with a laser. It is not necessary to use multiple passes or multiple laser heads to achieve a complex shape. It is not necessary to add special devices or processes for the laser-inaccessible locations. It is not necessary to restrict the irradiation direction, etc., and the problems of (v), (viii), and (ix) mentioned above can be solved.

[0272] Furthermore, in the laser welding apparatus described above, the formation of a roughly circular or oval-shaped weld portion from a top view, along with a large weld portion width, increases the margin for positional deviation relative to the laser or the welded component. Since laser irradiation is completed within this weld portion, burn-through control is not difficult due to the increased heat input as it progresses into the latter half of the weld. Moreover, the large weld portion width and deep penetration prevent heat concentration, resulting in a molten pool that symmetrically approximates both sides of the welded component, further suppressing angular deformation (strain). Furthermore, the increased width and depth of the melt allow for greater molten metal volume. With an appropriate gap, a portion of the molten metal can flow into the joint without the need for filler material or additional fillet weld shaping. Surface tension allows for the formation of an inwardly concave curved surface (R-shape) without additional treatment, resulting in a fillet weld portion where stress concentration is less likely to occur. Furthermore, since a portion of the added molten metal flows into the gaps between workpieces caused by low bevel precision due to the shearing or fracture surfaces of the stamping or by the precision error resulting from multiple overlapping pieces, sufficient bonding strength can be ensured, thus solving the problems mentioned above (i) to (iv), (vi), and (vii).

[0273] As described above, the laser welding apparatus according to the above solution can solve the problems mentioned in (i) to (ix). Therefore, in the laser welding apparatus according to the above solution, when welding metal components of various shapes to metal plates, it is possible to form fillet welds with a large positional margin, and even in the case of complex joint configurations, fillet welds can be formed without the need to add filler material, and joints can be performed with high productivity and high strength.

[0274] In the laser welding apparatus involved in the above scheme, the following range can be projected onto the other main surface of the first component, and the projected range is set as the area irradiated by the laser, i.e., the designated area. The range is the range of the first main surface of the first component that the second component abuts against or approaches, and the gap between the first main surface and the surface of the second component is equal to or less than 1 / 2 of the plate thickness of the first component.

[0275] As described above, by setting the area to be irradiated by the laser, i.e., the designated area, within the projected range, a sufficiently large fillet weld can be formed at the joint between the first and second components without adding filler material or additionally adding a shape to the components to form a fillet weld. Therefore, this method offers an advantage in achieving a stronger bond between the first and second components.

[0276] In the laser welding apparatus described above, when the laser is irradiated, the laser spot can be made to scan in a circular manner around a designated position with a center in the designated area of ​​the first component, with a diameter larger than the diameter of the laser spot.

[0277] As described above, when the weld portion and fillet weld portion are formed by scanning the laser spot around a designated position, since the weld portion is formed by melting and stirring the first and second components, even if there is a gap between the first and second components, molten metal can flow into the gap, resulting in a higher bonding strength.

[0278] The laser welding apparatus described above may further include: a filler material supply machine for supplying filler material; wherein, when the gap between the first component's main surface, which is abutted or approached by the second component, and the surface of the second component is equal to or greater than 1 / 2 the thickness of the first component, the width of the second component is projected onto the other main surface of the first component, and the projected area is set as the area to be irradiated by the laser, i.e., a designated area. During laser irradiation, the laser spot is made to circumferentially scan around a designated position with a center in the designated area of ​​the first component in a manner with a diameter greater than the diameter of the laser spot, and the filler material is supplied to the irradiation range of the laser.

[0279] As described above, when the gap is equal to or greater than half the thickness of the first member, supplying filler material within the laser irradiation range can suppress problems such as decreased joint strength and burn-through. Therefore, by employing the above solution, even when the gap is equal to or greater than half the thickness of the first member, the first member and the second member can be joined with high strength.

[0280] In the laser welding apparatus described above, multiple welded portions can be formed by irradiating the laser.

[0281] As described above, by forming multiple welded sections, it is possible to suppress problems such as burn-through caused by excessive heat input in the latter half of the weld and at the ends, and to join the first component and the second component with high strength.

[0282] In the laser welding apparatus described above, after multiple welding portions are formed at intervals from each other during laser irradiation, adjacent welding portions are connected to form a linear welding portion that appears as a line when viewed from above.

[0283] As described above, when a linear weld is formed by connecting adjacent welds to each other, airtightness can be ensured and working time can be reduced in locations with low stress.

[0284] In the laser welding apparatus described above, when the laser irradiates the welded portions, a linear welded portion that appears as a line when viewed from above can be continuously formed by connecting adjacent welded portions in a way that the multiple welded portions are formed apart from each other.

[0285] As described above, when a linear weld portion is continuously formed in the case of forming multiple weld portions (weld portions formed by scanning the spot in a circular motion), the same as when a linear weld portion is formed after forming multiple weld portions, it is possible to ensure gas sealing and reduce working time at low stress locations.

[0286] As described above, in each of the above solutions, when welding metal components of various shapes to metal plates, fillet welds can be formed with a large positional margin, and even in the case of complex joint configurations, fillet welds can be formed without the need to add filler material, and joints can be performed with high productivity and high strength.

Claims

1. A laser welding method for joining a plate-shaped first component made of metal material to a second component made of metal material as a tube by laser welding, characterized in that... include: The configuration step involves making a portion of the outer peripheral surface of the second component abut or approach a main surface of the first component; as well as, In the laser irradiation step, a laser is irradiated onto the main surface opposite to one of the main surfaces of the first component, i.e., the other main surface of the first component, which is abutted or approached by the second component; wherein, In the laser irradiation step, the first component and the second component are melted to form: Multiple welded portions, each having a generally circular or oval shape when viewed from above, and arranged at intervals from each other when viewed from above; A linear weld portion, formed in such a way as to connect adjacent weld portions to each other, and appearing linear when viewed from above; and A fillet weld is formed at the joint between the first component and the second component. In the configuration step, the second member is configured relative to the first member such that a portion of the outer peripheral surface of the second member, which abuts or approaches a main surface of the first member, is only a linear region extending along the radial center of the second member when viewed from above. In the laser irradiation step, the linear weld portion is formed such that at least a portion of the linear weld portion passes through the linear region when viewed from above.

2. The laser welding method according to claim 1, characterized in that: The following range is projected onto the other main surface of the first member, and the projected range is set as the area irradiated by the laser, i.e., the designated area, which is the range of the first member's main surface that the second member abuts against or approaches, and the gap between the main surface and the surface of the second member is equal to or less than 1 / 2 of the thickness of the first member.

3. The laser welding method according to claim 2, characterized in that: In the laser irradiation step, the laser spot is made to scan in a circular motion around a designated position having a center in the designated area of ​​the first member, with a diameter larger than the diameter of the laser spot.

4. A laser welding apparatus for joining a plate-shaped first component made of metal material to a second component made of metal material as a tube by laser welding, characterized in that... include: Laser oscillator, which generates laser light; The focusing section concentrates the laser beam; The scanning unit scans the laser beam. as well as, The control unit controls the laser oscillator and the scanning unit; wherein, The control unit, With a portion of the outer peripheral surface of the second component abutting or approaching a main surface of the first component, The laser is directed to the main surface opposite to one of the main surfaces of the first component that is abutted or approached by the second component, i.e., the other main surface of the first component. The first and second components are melted by irradiation with the laser to form: a plurality of weld portions, each having a generally circular or oval shape in plan view and arranged spaced apart from each other in plan view; linear weld portions formed to connect adjacent weld portions and appearing linear in plan view; and fillet weld portions formed at the joint between the first and second components. The second member is configured to abut or approach the first member in a linear region extending only along the radial center of the second member when viewed from above, such that it comes into contact with or approaches one of the main surfaces of the first member. When irradiated by the laser, the linear weld portion is formed such that at least a portion of the linear weld portion passes through the linear region when viewed from above.

5. The laser welding apparatus according to claim 4, characterized in that: The following range is projected onto the other main surface of the first member, and the projected range is set as the area irradiated by the laser, i.e., the designated area, which is the range of the first member's main surface that the second member abuts against or approaches, and the gap between the main surface and the surface of the second member is equal to or less than 1 / 2 of the thickness of the first member.

6. The laser welding apparatus according to claim 5, characterized in that: When the laser is irradiated, the laser spot is made to scan in a circular motion around a designated position having a center in the designated area of ​​the first component, with a diameter larger than the diameter of the laser spot.

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