Laser welding method

Abstract

To provide a laser welding method that can suppress damage to a component due to plume that is generated when a laser beam is emitted.SOLUTION: A laser welding method according to an embodiment comprises a first step, a second step and a third step. In the first step, a first member having an opening on one side and a second member having a third member attached to a surface on the one side are prepared, and an assembly with the opening covered with a surface on the other side of the second member is assembled. In the second step, a first laser beam is emitted from the one side to a corner part on the one side of the assembly to process the corner part into a curved surface. In the third step, a second laser beam is emitted from the one side to the curved surface to weld the second member to the first member.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a laser welding method. [Background technology]

[0002] There is a laser welding method in which a first member is welded to a second member by irradiating the first member with a laser beam while the opening of the first member is covered with the second member. In such a laser welding method, for example, the second member is welded to the first member by irradiating a laser beam from the opening side to the vicinity of a corner of the surface of the first member or the second member on the opening side.

[0003] In such a laser welding method, if a third member is attached to the opening side surface of the second member when the laser light is irradiated, part of the plume generated when the laser light is irradiated may hit the third member, causing damage to the third member. [Prior art documents] [Non-patent literature]

[0004] [Patent Document 1] JP 2017-54786 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a laser welding method capable of suppressing damage to components caused by a plume generated when irradiated with laser light. [Means for solving the problem]

[0006] The laser welding method according to the embodiment includes a first step, a second step, and a third step. In the first step, a first member having an opening on one side and a second member having a third member attached to a surface of the one side are prepared, and an assembly is assembled in which the opening is closed by the surface of the other side of the second member. In the second step, a first laser beam is irradiated from the one side to a corner of the one side of the assembly, thereby processing the corner into a curved surface. In the third step, a second laser beam is irradiated from the one side to the curved surface, thereby welding the second member to the first member. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a perspective view illustrating a first step of the laser welding method according to the embodiment. [Diagram 2] FIG. 4 is a perspective view illustrating a second step of the laser welding method according to the embodiment. [Diagram 3] FIG. 4 is a perspective view illustrating a third step of the laser welding method according to the embodiment. [Figure 4] 4(a) to 4(e) are cross-sectional views illustrating a second step of the laser welding method according to the embodiment. [Diagram 5] FIG. 4 is a cross-sectional view illustrating a third step of the laser welding method according to the embodiment. [Figure 6] 4 is a plan view showing a region irradiated with a first laser beam in a second step of the laser welding method according to the embodiment. FIG. [Figure 7] 7(a) to 7(e) are cross-sectional views illustrating a second step of the laser welding method according to the modified embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0009] FIG. 1 is a perspective view illustrating a first step of a laser welding method according to an embodiment. FIG. 2 is a perspective view illustrating a second step of the laser welding method according to the embodiment. FIG. 3 is a perspective view illustrating a third step of the laser welding method according to the embodiment. As shown in FIGS. 1 to 3, the laser welding method according to the embodiment includes a first step, a second step, and a third step.

[0010] In the laser welding method according to the embodiment, first, a first step is performed. In the first step, a first member 10 and a second member 20 to be welded are prepared as shown in FIG.

[0011] The first member 10 and the second member 20 include, for example, at least one of aluminum, iron, and SUS (Stainless Used Steel). The material of the second member 20 may be the same as the material of the first member 10, or may be different.

[0012] The first member 10 is, for example, a housing having an opening 16 on one side. The first member 10 has, for example, a substantially rectangular box-like structure with one side open. The first member 10 has, for example, a first side portion 11, a second side portion 12, a third side portion 13, a fourth side portion 14, and a bottom portion 15. The bottom portion 15 is located at the bottom (the other end portion) of the first member 10. The first side portion 11, the second side portion 12, the third side portion 13, and the fourth side portion 14 are each an upright portion rising from the bottom portion 15 to one side. The first side portion 11 and the third side portion 13 face each other. The second side portion 12 and the fourth side portion 14 face each other. The first member 10 has an opening 16 formed, for example, by one end of the first side portion 11, one end of the second side portion 12, one end of the third side portion 13, and one end of the fourth side portion 14.

[0013] The second member 20 is, for example, a lid that closes the opening 16 of the first member 10. The second member 20 has, for example, a flat plate-like structure. The second member 20 has a surface 20a on one side and a surface 20b on the other side. The surface 20a on the one side is, for example, an upper surface. The surface 20b on the other side is, for example, a lower surface.

[0014] A third member 30 is attached to one surface 20a of the second member 20. In this example, two third members 30 (third member 31 and third member 32) are attached to one surface 20a of the second member 20. The third members 30 are, for example, resin parts. The third members 30 are, for example, insulating materials. The number of third members 30 is not limited to two, and may be one, or three or more.

[0015] In the first step, next, an assembly 50 (see FIG. 2) is assembled in which the opening 16 is closed by the other surface 20b of the second member 20. The other surface 20b of the second member 20 corresponds to the inner surface of the assembly 50. The one surface 20a of the second member 20 corresponds to the outer surface of the assembly 50. In other words, the third member 30 is located outside the assembly 50.

[0016] Depending on the application, parts, liquid, and the like may be contained inside the assembled body 50. In this case, the assembled body 50 is assembled in a state where the parts, liquid, and the like are contained inside the first member 10.

[0017] In the laser welding method according to the embodiment, a second step is then performed. In the second step, as shown in Fig. 2, a corner 51 on one side of the assembled body 50 is irradiated with a first laser beam 210 from one side, thereby processing the corner 51 into a curved surface 55. As will be described later, the corner 51 on one side of the assembled body 50 may be a corner on one side of the second member 20 or a corner on one side of the first member 10.

[0018] The laser device that irradiates the first laser light 210 is, for example, a CW (Continuous Wave) laser device that continuously oscillates a constant output. The laser device that irradiates the first laser light 210 may be a pulsed laser device that oscillates a pulsed output at a constant repetition frequency (pulse width). In the case of a pulsed laser device, the pulse width is, for example, several femtoseconds, several picoseconds, or several milliseconds. The wavelength of the first laser light 210 is, for example, not less than 700 nm and not more than 2000 nm.

[0019] In the laser welding method according to the embodiment, the third step is then performed. In the third step, as shown in Fig. 3, the second laser light 220 is irradiated from one side of the curved surface 55 to weld the second member 20 to the first member 10. As a result, for example, a sealed member is manufactured in which the opening 16 of the first member 10 (housing) is sealed by the second member 20 (lid).

[0020] The laser device that irradiates the second laser light 220 is, for example, a pulsed laser device. The laser device that irradiates the second laser light 220 may be a CW laser device. In the case of a pulsed laser device, the pulse width is, for example, several femtoseconds, several picoseconds, or several milliseconds. The wavelength of the second laser light 220 is, for example, 700 nm or more and 2000 nm or less.

[0021] The output of the first laser beam 210 is, for example, smaller than the output of the second laser beam 220. The irradiation of the first laser beam 210 is performed, for example, by thermal conduction welding. The irradiation of the second laser beam 220 is performed, for example, by keyhole welding.

[0022] The second step will be described in more detail below. 4(a) to 4(e) are cross-sectional views illustrating a second step of the laser welding method according to the embodiment. As shown in Fig. 4(a) to Fig. 4(e), in the second step, a corner 51 on one side of the assembled body 50 is irradiated with a first laser beam 210 from one side, thereby processing the corner 51 into a curved surface 55. The curved surface 55 has an outwardly convex shape. The curved surface 55 has, for example, a curvature. The curved surface 55 may have a uniform curvature, or may not have a uniform curvature.

[0023] In this example, the assembly 50 is assembled in a state where one end of the first member 10 is covered by the second member 20. That is, in this example, a corner 51 on one side of the assembly 50 is a corner on one side of the second member 20. In this example, the corner 51 is a corner formed by a surface 20a on one side of the second member 20 and a side surface 20c intersecting (for example, perpendicular to) the surface 20a on one side of the second member 20. The first member 10 and the second member 20 are assembled, for example, so that the interior angle between the first member 10 and the second member 20 is 90 degrees.

[0024] As shown in Figures 4(a) and 4(b), when corner 51 is irradiated with first laser beam 210 from one side, a part of corner 51 (a part of second member 20) melts to become molten portion 52. As shown in Figure 4(c), when irradiation with first laser beam 210 is continued, molten portion 52 spreads. As shown in Figures 4(d) and 4(e), when irradiation with first laser beam 210 is stopped, molten portion 52 sags due to gravity, and a smooth curved surface 55 is formed at corner 51. Molten portion 52 solidifies with curved surface 55 formed.

[0025] 4(a) to 4(c), in the second step, it is preferable to irradiate the first laser beam 210 so that the center 210a of the first laser beam 210 overlaps with one side surface 10a of the first member 10. Also, as shown in Fig. 4(c), in the second step, irradiation of the first laser beam 210 is continued until the melted portion 52 spreads to a position including the outer circumferential edge 51e of the corner 51. The outer circumferential edge 51e of the corner 51 is the edge of the assembly 50 in a plan view.

[0026] Also, as shown in FIG. 4(c) to FIG. 4(e), in this example, the melted portion 52 reaches the boundary between the first member 10 and the second member 20 in the second step. That is, in this example, the first member 10 and the second member 20 are joined in the second step. In this manner, in the laser welding method according to the embodiment, the first member 10 and the second member 20 may be joined in the second step. For example, by increasing the output of the first laser light 210, the first member 10 and the second member 20 can be joined in the second step, and the corner portion 51 can be processed into the curved surface 55. For example, by decreasing the output of the first laser light 210, the corner portion 51 can be processed into the curved surface 55 in the second step, without joining the first member 10 and the second member 20.

[0027] In the second step, the first laser light 210 is irradiated onto one surface of the assembly 50 (for example, one surface 20a of the second member 20). Therefore, depending on the irradiation conditions of the first laser light 210, a plume may be generated in the second step. Therefore, it is preferable to set the output of the first laser light 210 smaller than the output of the second laser light 220. This makes it possible to suppress the generation of the plume in the second step. In addition, it is preferable that the irradiation of the first laser light 210 is performed by thermal conduction welding. This makes it possible to suppress the generation of the plume in the second step, for example, compared to the case where the irradiation of the first laser light 210 is performed by keyhole welding.

[0028] FIG. 5 is a cross-sectional view illustrating a third step of the laser welding method according to the embodiment. 5, in the third step, the second member 20 is welded to the first member 10 by irradiating the curved surface 55 with the second laser beam 220 from one side. In the third step, it is preferable to irradiate the second laser beam 220 such that the center 220a of the second laser beam 220 overlaps with the curved surface 55, for example.

[0029] As shown in Fig. 5, by irradiating curved surface 55 with second laser light 220 from one side, the direction of plume PL generated when irradiated with second laser light 220 can be tilted outward. In Fig. 5, the direction of plume PL is shown diagrammatically by a two-dot chain line. By tilting the direction of plume PL outward, it is possible to prevent plume PL generated when irradiated with second laser light 220 from hitting third member 30, and therefore to prevent damage to third member 30.

[0030] Moreover, the third step is preferably performed consecutively, for example, using the same laser device as the second step. By performing the third step consecutively with the second step, the second laser light 220 can be irradiated in the third step to the same position as the position irradiated with the first laser light 210 in the second step. That is, in the third step, the second laser light 220 can be irradiated to the curved surface 55 more reliably without performing position detection or alignment of the curved surface 55.

[0031] FIG. 6 is a plan view showing a region irradiated with the first laser light in the second step of the laser welding method according to the embodiment. 6, in the second step, it is preferable to irradiate the first laser light 210 only near the third member 30. In Fig. 6, laser light irradiation regions 53a to 53d to be irradiated with the first laser light 210 are shown by hatching.

[0032] The laser light irradiation region 53a and the laser light irradiation region 53b are regions of the corner portion 51 that are located in the vicinity of the third member 31. The laser light irradiation region 53a and the laser light irradiation region 53b face each other with the third member 31 in between. The third member 31 is located between the laser light irradiation region 53a and the laser light irradiation region 53b.

[0033] The laser light irradiation region 53a and the laser light irradiation region 53b are, for example, regions of the corner 51 where the distance L1 between the outer circumferential edge 51e of the corner 51 and the outer circumferential edge 31e of the third member 31 is 5 mm or less. In this example, the laser light irradiation region 53a and the laser light irradiation region 53b are portions of the corner 51 where the outer circumferential edge 51e of the corner 51 and the outer circumferential edge 31e of the third member 31 are aligned in parallel.

[0034] The laser light irradiation region 53c and the laser light irradiation region 53d are regions of the corner portion 51 that are located near the third member 32. The laser light irradiation region 53c and the laser light irradiation region 53d face each other with the third member 32 in between. The third member 32 is located between the laser light irradiation region 53c and the laser light irradiation region 53d.

[0035] The laser light irradiation region 53c and the laser light irradiation region 53d are, for example, regions of the corner 51 where the distance L2 between the outer circumferential edge 51e of the corner 51 and the outer circumferential edge 32e of the third member 32 is 5 mm or less. In this example, the laser light irradiation region 53c and the laser light irradiation region 53d are portions of the corner 51 where the outer circumferential edge 51e of the corner 51 and the outer circumferential edge 32e of the third member 32 are aligned in parallel.

[0036] By irradiating the first laser light 210 only near the third member 30, it is possible to suppress thermal damage to the assembly 50 in the second step while suppressing damage to the third member 30 caused by the plume PL generated when the second laser light 220 is irradiated in the third step.

[0037] 7(a) to 7(e) are cross-sectional views illustrating a second step of the laser welding method according to the modified embodiment. As shown in Fig. 7(a) to Fig. 7(e), in this example, the assembly 50 is assembled in a state in which the second member 20 is positioned between the ends of one side of the first member 10. That is, in this example, a corner 51 on one side of the assembly 50 is a corner on one side of the first member 10. In this example, the corner 51 is a corner formed by a surface 10a on one side of the first member 10 and a side surface 10c intersecting (for example, perpendicular to) the surface 10a on one side of the first member 10. In this example as well, the first member 10 and the second member 20 are assembled such that the interior angle between the first member 10 and the second member 20 is, for example, 90 degrees.

[0038] As shown in Figures 7(a) and 7(b), when corner 51 is irradiated with first laser beam 210 from one side, a part of corner 51 (a part of first member 10) melts and becomes molten portion 52. As shown in Figure 7(c), when irradiation of first laser beam 210 is continued, molten portion 52 spreads. As shown in Figures 7(d) and 7(e), when irradiation of first laser beam 210 is stopped, molten portion 52 sags due to gravity, and a smooth curved surface 55 is formed at corner 51. Molten portion 52 solidifies with curved surface 55 formed.

[0039] 7(a) to 7(c), in the second step, it is preferable to irradiate the first laser beam 210 so that the center 210a of the first laser beam 210 overlaps with the first member 10. Also, as shown in Fig. 7(c), in the second step, irradiation of the first laser beam 210 is continued until the melted portion 52 spreads to a position including the outer circumferential end 51e of the corner portion 51.

[0040] Also, as shown in FIG. 7(c) to FIG. 7(d), in this example, the melted portion 52 reaches the boundary between the first member 10 and the second member 20 in the second step. That is, in this example, the first member 10 and the second member 20 are joined in the second step. In this manner, in the laser welding method according to the modified example of the embodiment, the first member 10 and the second member 20 may be joined in the second step. For example, by increasing the output of the first laser light 210, the first member 10 and the second member 20 can be joined in the second step, and the corner portion 51 can be processed into the curved surface 55. For example, by decreasing the output of the first laser light 210, the corner portion 51 can be processed into the curved surface 55 in the second step, without joining the first member 10 and the second member 20.

[0041] Also in this example, it is preferable to set the output of the first laser beam 210 smaller than the output of the second laser beam 220. This makes it possible to suppress the generation of plumes in the second step. Also in this example, it is preferable to perform the irradiation of the first laser beam 210 by thermal conduction welding. This makes it possible to suppress the generation of plumes in the second step, for example, compared to the case where the irradiation of the first laser beam 210 is performed by keyhole welding.

[0042] The embodiment may include the following features.

[0043] (Configuration 1) a first step of preparing a first member having an opening on one side and a second member having a third member attached to a surface of the first side, and assembling an assembly in which the opening is closed by a surface of the other side of the second member; a second step of irradiating a corner portion on the one side of the assembly with a first laser light from the one side to process the corner portion into a curved surface; a third step of welding the second member to the first member by irradiating the curved surface from the one side with a second laser light; A laser welding method comprising:

[0044] (Configuration 2) the first member is a housing, the second member is a lid, 2. The laser welding method according to claim 1, wherein the third member is a resin part.

[0045] (Configuration 3) 3. The laser welding method according to claim 1, wherein in the second step, the first laser light is irradiated only to a vicinity of the third member.

[0046] (Configuration 4) 4. The laser welding method according to any one of configurations 1 to 3, wherein in the third step, the second laser beam is irradiated so that a center of the second laser beam overlaps with the curved surface.

[0047] (Configuration 5) 5. The laser welding method according to any one of configurations 1 to 4, wherein an output of the first laser beam is smaller than an output of the second laser beam.

[0048] (Configuration 6) The irradiation of the first laser light is performed by thermal conduction welding, 6. The laser welding method according to any one of configurations 1 to 5, wherein the irradiation of the second laser light is performed by keyhole welding.

[0049] As described above, according to the embodiment, a laser welding method is provided that can suppress damage to components due to the plume generated when irradiating with laser light.

[0050] The laser welding method according to the embodiment is suitably used for manufacturing devices such as secondary batteries.

[0051] Although the embodiment of the present invention has been illustrated above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This new embodiment can be implemented in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0052] 10: First member 10a: One side 10c: Side 11~14: 1st~4th side part 15: Bottom part 16: Opening 20: Second member 20a: One side 20b: Other side 20c: Side 30, 31, 32: third member 31e, 32e: Outer edge 50: Assembly 51: Corner 51e: Outer edge 52:Melted part 53a to 53d: laser light irradiation areas 55: Curved surface 210: First laser light 210a: Center 220: Second laser light 220a: Center L1, L2: distance PL: Plume

Claims

1. a first step of preparing a first member having an opening on one side and a second member having a third member attached to a surface of the one side, and assembling an assembly in which the opening is closed by a surface of the other side of the second member; a second step of irradiating a corner portion on the one side of the assembly with a first laser light from the one side to process the corner portion into a curved surface; a third step of welding the second member to the first member by irradiating the curved surface from the one side with a second laser light; A laser welding method comprising:

2. the first member is a housing, the second member is a lid, The laser welding method according to claim 1 , wherein the third member is a resin part.

3. The laser welding method according to claim 1 , wherein in the second step, the first laser light is irradiated only to a vicinity of the third member.

4. The laser welding method according to claim 1 , wherein in the third step, the second laser beam is irradiated so that a center of the second laser beam overlaps with the curved surface.

5. The laser welding method according to claim 1 , wherein an output of the first laser beam is smaller than an output of the second laser beam.

6. The laser welding method according to claim 5 , wherein the irradiation of the first laser light is performed by thermal conduction welding.

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