Welding method

Abstract

To provide a welding method that can improve quality.SOLUTION: A welding method includes a process in which a welded component containing aluminum is prepared. The welding method includes a process in which in the state that a gas containing oxygen is supplied to a weldment area of a surface of the welded component, the weldment area is irradiated with laser, thereby welding the weldment area. A concentration of oxygen in the gas is 1.5 vol% or more and 10 vol% or less. The weldment area after irradiated with laser contains oxide aluminum.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a welding method. [Background technology]

[0002] For example, the housings of batteries and the like are manufactured by welding, and there is a demand for improved quality in the welding. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-141763 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE DISCLOSURE Embodiments of the present invention provide a welding method that can improve quality. [Means for solving the problem]

[0005] According to an embodiment of the present invention, a welding method includes preparing workpieces containing aluminum. The welding method includes irradiating a laser to a welding area on a surface of the workpiece while supplying a gas containing oxygen to the welding area to weld the welding area. The concentration of the oxygen in the gas is 1.5 vol% or more and 10 vol% or less. The welding area after being irradiated with the laser contains aluminum oxide. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic perspective view illustrating a welding method according to the first embodiment. [Diagram 2] FIG. 2 is a flow chart illustrating the welding method according to the first embodiment. [Diagram 3] 3(a) and 3(b) are schematic diagrams illustrating the welding state. [Figure 4] 4(a) and 4(b) are schematic diagrams illustrating the welding state. [Diagram 5] 5(a) and 5(b) are schematic diagrams illustrating the welding state. [Figure 6] 6(a) to 6(c) are graphs illustrating the evaluation results of welding. [Figure 7] 7(a) to 7(i) are photographic images illustrating the welding state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. 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.

[0008] (First embodiment) FIG. 1 is a schematic perspective view illustrating a welding method according to the first embodiment. FIG. 2 is a flow chart illustrating the welding method according to the first embodiment. 1, in the welding method according to the embodiment, a laser 10 is irradiated onto workpieces 50 while gas 20 is being supplied to the workpieces 50. The welding method according to the embodiment is performed using a welding device 110, for example.

[0009] The welding device 110 may include, for example, a laser emission unit 10L, an irradiation head 10H, a gas supply unit 20s, a driving unit 75, and a control unit 70. The laser emission unit 10L emits a laser 10 (laser light). The laser 10 is irradiated to the workpiece 50 via the irradiation head 10H. For example, the irradiation head 10H supports a gas supply unit 20s. The gas supply unit 20s supplies gas 20 toward the workpiece 50. The driving unit 75 can change the relative position between the irradiation head 10H and the workpiece 50. The driving unit 75 can scan the irradiation head 10H. The control unit 70 controls at least one of the laser emission unit 10L, the irradiation head 10H, the gas supply unit 20s, and the driving unit 75.

[0010] For example, the welded members 50 include aluminum. The welded members 50 may further include at least one selected from the group consisting of Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti, V, Bi, Pb, and Zr. The aluminum composition ratio in the welded members 50 is 90 wt % or more. For example, multiple portions of the welded members 50 are welded and joined.

[0011] A plane along at least a part of the surface 50s of the workpiece 50 is defined as the XY plane. A direction perpendicular to the XY plane is defined as the Z-axis direction. For example, the irradiation head 10H scans the workpiece 50 along the direction AR within the plane along the surface 50s (within the XY plane). In the scan, the irradiation head 10H may move, or the workpiece 50 may move. The direction AR is, for example, the X-axis direction.

[0012] In the embodiment, the laser 10 is irradiated onto the welding area 50r on the surface 50s of the workpiece 50 while a gas 20 containing oxygen is being supplied to the welding area 50r. As a result, the welding area 50r is welded.

[0013] The gas 20 includes oxygen 21. It further includes another gas 22. The other gas 22 includes, for example, at least one selected from the group consisting of nitrogen and argon. The other gas 22 may be air.

[0014] In the embodiment, the concentration of oxygen 21 in the gas 20 is 1.5 vol% or more and 10 vol% or less. When the other gas 22 is air, the oxygen 21 concentration is calculated including the oxygen component contained in the air. It has been found that good welding is possible at such a concentration of oxygen 21. In the present specification and drawings, "vol%" may be abbreviated to "%" with respect to the gas concentration.

[0015] As shown in FIG. 2, the welding method according to the embodiment includes preparing a welded member 50 containing aluminum (step S110).

[0016] 2, the welding method according to the embodiment includes supplying gas 20 containing oxygen 21 to a welding region 50r on a surface 50s of a workpiece 50, and then irradiating the welding region 50r with a laser 10 to weld the welding region 50r (step S120). In the embodiment, the concentration of oxygen 21 in the gas 20 is 1.5 vol% or more and 10 vol% or less.

[0017] The welding method according to the embodiment may further include mixing another gas 22 with oxygen 21 to prepare the gas 20 .

[0018] An example of the welding state will now be described. 3(a) and 3(b) are schematic diagrams illustrating the welding state. In these figures, the gas 20 does not contain oxygen 21. The gas 20 contains substantially only nitrogen. The concentration C1 of oxygen 21 in the gas 20 is 0.0 vol%. FIG. 3(a) is an optical microscope image of the welded region 50r during welding. FIG. 3(b) is a schematic diagram drawn based on the results of optical microscope observation. The flow rate of the gas 20 is 30 L / min (liters / minute).

[0019] As shown in FIG. 3(a) and FIG. 3(b), in the welding region 50r, a wave 55 is generated in the workpiece 50 that has become liquid due to irradiation with the laser 10. The wave 55 moves from the end 55a toward the keyhole 56. The movement is considered to be based on, for example, Marangoni convection. A part of the wave 55 covers a part of the keyhole 56. When the wave 55 enters a part of the keyhole 56, the shape of the keyhole 56 is disturbed due to vibration of the liquid surface. The multiply reflected laser 10 is irradiated to the inside of the keyhole 56, and the liquid workpiece 50 is scattered due to vapor pressure. For example, spattering occurs. This makes the welding unstable. Welding defects are likely to occur. For example, the quality of the welding is likely to be low.

[0020] 4(a) and 4(b) are schematic diagrams illustrating the welding state. In these figures, the gas 20 contains oxygen 21 and nitrogen. The concentration C1 of the oxygen 21 in the gas 20 is 10.0 vol%. Fig. 4(a) is an optical microscope image of the welded region 50r during welding. Fig. 4(b) is a schematic diagram drawn based on the results of optical microscope observation. The flow rate of the gas 20 is 30 L / min.

[0021] As shown in FIG. 4(a) and FIG. 4(b), in the welding region 50r, the movement of the waves 55 of the workpieces 50 that have become liquid due to the irradiation of the laser 10 is slight. For example, Marangoni convection does not occur substantially. Therefore, the waves 55 are prevented from covering a part of the keyhole 56. Spatter is prevented. This makes the welding stable. Welding defects can be prevented. For example, high quality welding can be obtained.

[0022] As described above, the movement of the waves 55 is suppressed when the gas 20 contains the oxygen 21. It is believed that the reason the movement of the waves 55 is suppressed is that part of the aluminum contained in the workpieces 50 is oxidized by the oxygen 21. It is believed that the movement of the liquid workpieces 50 can be suppressed because the melting point of aluminum oxide is high.

[0023] Thus, in the embodiment, the gas 20 contains oxygen 21, which can suppress the movement of the wave 55. For example, the welded area 50r after being irradiated with the laser 10 contains aluminum oxide. According to the embodiment, a welding method capable of improving quality can be provided.

[0024] For example, in the case of welding steel mainly composed of iron, it has been proposed to use a shielding gas containing oxygen for the purpose of omitting heat treatment after welding or improving the fluidity of the molten metal.

[0025] In contrast, in the embodiment, welding of a welded member 50 containing aluminum is performed. In general, when welding a material containing aluminum, a gas containing oxygen is not used. This is because it is thought that the material containing aluminum is oxidized by oxygen, causing a change in properties, and oxidation should be avoided.

[0026] In the embodiment, gas 20 containing oxygen 21 is used, which is not generally used when welding materials containing aluminum. For example, oxidation of aluminum is utilized for stable welding. This enables stable welding as described above. A new effect of suppressing the movement of wave 55 is utilized by gas 20 containing oxygen 21. This effect is different from the effect when a shielding gas containing oxygen is used in welding steel materials.

[0027] In the embodiment, if the concentration of oxygen 21 is excessively high, the characteristics deteriorate. For this reason, the concentration C1 of oxygen 21 in the gas 20 is set to 10 vol% or less. This prevents excessive oxidation and provides good quality welding. An example of the concentration C1 of oxygen 21 will be described below.

[0028] 5(a) and 5(b) are schematic diagrams illustrating the welding state. These figures show examples of microscope observation images of welded members 50 after welding. In Fig. 5(a), the oxygen concentration C1 is 4.0 vol%. In Fig. 5(b), the oxygen concentration C1 is 20.0 vol%.

[0029] As shown in FIG. 5(a), when the oxygen concentration C1 is 4.0 vol%, traces of waves 55 are clearly observed. The waves 55 are aligned along the X-axis direction, which is parallel to the scanning direction (direction AR: see FIG. 1). When the oxygen concentration C1 is 4.0 vol%, good welding is obtained.

[0030] As shown in FIG. 5(b), when the oxygen concentration C1 is 20.0 vol%, the traces of the waves 55 are not substantially observed. Random irregularities are observed. It was found that when the oxygen concentration C1 is 20.0 vol%, welding defects occur. This is believed to be caused by the oxygen concentration C1 being excessively high.

[0031] 6(a) to 6(c) are graphs illustrating the evaluation results of welding. 7(a) to 7(i) are photographic images illustrating the welding state. As shown in FIG. 7(a) to FIG. 7(i), when the oxygen concentration C1 changes, the state of the welded portion changes. The horizontal axis of Fig. 6(a) to Fig. 6(c) is the concentration C1 of oxygen 21 in gas 20. The vertical axis of Fig. 6(a) is the defect occurrence rate DF1 in welding. The defect occurrence rate DF1 is the number of defects that occur in a welding length of 1.6 m. As shown in Fig. 6(a), in a region where the concentration C1 of oxygen 21 is 10 vol% or less, as the concentration C1 increases, the defect occurrence rate DF1 decreases. When the concentration C1 is 20.0 vol%, welding defects occur at many positions in the welding. The concentration C1 of oxygen 21 is preferably 1.5 vol% or more. Welding defects can be reduced.

[0032] The vertical axis of FIG. 6(b) is the first parameter P1 related to oxidation. The optical properties (color or reflectance) of the welded portion change depending on the degree of oxidation. In this example, the first parameter P1 corresponds to the optical reflectance in a direction inclined with respect to the surface 50s (see FIG. 1) of the welded member 50. When the first parameter P1 is small, the degree of oxidation is low. When the first parameter P1 is large, the degree of oxidation is high. As shown in FIG. 6(b), when the concentration C1 of oxygen 21 is 2.7 vol% or more, the first parameter P1 becomes large. When the concentration C1 of oxygen 21 is 2.7 vol% or more, it is considered that oxidation progresses. When the concentration C1 is 20.0 vol%, it is considered that excessive oxidation occurs. In the embodiment, the concentration C1 is preferably 1.5 vol% or more and 10 vol% or less. Welding becomes stable. Welding defects can be suppressed. For example, high-quality welding can be obtained.

[0033] The vertical axis of FIG. 6(c) is the second parameter P2 related to the plurality of waves 55. As already described, when good welding is obtained, the plurality of waves 55 are aligned along the scanning direction (see FIG. 5(a)). The second parameter P2 relates to the uniformity of the arrangement of the plurality of waves 55. The second parameter P2 corresponds to the fluctuation of the interval along the scanning direction of the plurality of irregularities (waves 55) formed in the welding area 50r. As shown in FIG. 6(c), when the concentration C1 is low, the second parameter P2 is small. When the concentration C1 is large, the second parameter P2 is large. For example, as described with reference to FIG. 5(b), when the concentration C1 is 20.0 vol%, random irregularities are observed. In this case, the second parameter P2 is very large. In the embodiment, the second parameter P2 is preferably 20% or less.

[0034] Thus, in the welding method according to the embodiment, the relative position between the workpiece 50 and the laser 10 is changed (scanned) in a plane along the surface 50s along the first direction (the X-axis direction, direction AR). In this example, the fluctuation in the spacing along the first direction of the multiple irregularities (waves 55) formed in the welding area 50r is preferably 20% or less. This makes the welding stable. This makes it possible to suppress welding defects. For example, high quality welding can be obtained. From FIG. 6(c), it is preferable that the concentration C1 is 10 vol% or less.

[0035] In one example according to the embodiment, the wavelength of the laser 10 is, for example, 450 nm or more and 1090 nm or less. In one example, the output of the laser 10 is, for example, 500 W or more and 20,000 W or less. In one example, the speed (scanning speed) of changing (scanning) the relative position between the workpieces 50 and the laser 10 is, for example, 50 mm / s or more and 2,000 mm / s or less.

[0036] Second embodiment The second embodiment relates to a welding apparatus 110. As described with reference to Fig. 1, the welding apparatus 110 includes, for example, a laser emission unit 10L, an irradiation head 10H, a gas supply unit 20s, a driving unit 75, and a control unit 70. The welding method described with reference to the first embodiment is performed in the welding apparatus 110. A welding apparatus capable of improving quality can be provided.

[0037] According to the embodiment, a welding method capable of improving quality can be provided.

[0038] The above describes the embodiment of the present invention with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configuration of each element, such as a laser, used in the welding method is included in the scope of the present invention as long as a person skilled in the art can implement the present invention in a similar manner and obtain similar effects by appropriately selecting the specific configuration from the known range.

[0039] Furthermore, any combination of two or more elements of each of the specific examples, within the scope of technical feasibility, is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0040] In addition, all quality-improving welding methods that can be implemented by a person skilled in the art through appropriate design modifications based on the quality-improving welding methods described above as embodiments of the present invention also fall within the scope of the present invention as long as they include the gist of the present invention.

[0041] In addition, within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and it will be understood that these modifications and alterations also fall within the scope of the present invention.

[0042] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0043] 10...laser, 10H...irradiation head, 10L...laser emission section, 20...gas, 20s...gas supply section, 21...oxygen, 22...other gas, 50...workpiece to be welded, 50s...surface, 55...wave, 55a...edge, 56...keyhole, 70...control section, 75...drive section, 110...welding device, AR...direction, C1...concentration, DF1...defect occurrence rate, P1, P2...first and second parameters

Claims

1. A welded member having an aluminum composition ratio of 90 wt % or more is prepared; a gas containing oxygen is supplied to a welding area on a surface of the workpiece, and a laser is irradiated onto the welding area to weld the welding area; The concentration of the oxygen in the gas is 1.5 vol% or more and 10 vol% or less, the welded area after the laser is irradiated includes aluminum oxide; The wavelength of the laser is not less than 450 nm and not more than 1090 nm, The output of the laser is 500 W or more and 20,000 W or less, Varying the relative position between the workpiece and the laser within a plane along the surface; A welding method, wherein the rate of change is 50 mm / s or more and 2,000 mm / s or less.

2. The method of claim 1 , wherein the gas further comprises at least one selected from the group consisting of nitrogen and argon.

3. The method of claim 1 further comprising providing said gas by mixing air and oxygen.

4. The welding method according to any one of claims 1 to 3, wherein the concentration of the oxygen in the gas is 2.7 vol % or more.

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