Joining method of dissimilar metal plates, joining apparatus and joined body

Abstract

To provide a joining method of dissimilar metal plates, a joining apparatus, and a joined body, which are capable of increasing a joint strength of the dissimilar metal plates.SOLUTION: A joining method of dissimilar metal plates comprises: a placement step of forming an overlapping portion 53 where a first metal plate 51 and a second metal plate 52 are overlapped with each other; and a laser welding step of irradiating a laser beam LB onto the overlapping portion 53. In the laser welding step, while moving, in a prescribed direction Y, an irradiation point of the laser beam LB with respect to the overlapping portion 53, the method reciprocates the irradiation point in an orthogonal direction X to form a welded part 6 along a sine-wave-shaped irradiation locus LL having a prescribed amplitude A on the overlapping portion 53. Therein, a plurality of irradiation loci LL are drawn so as to be separated from each other in the orthogonal direction X, and when viewed in the prescribed direction Y, one of adjacent irradiation loci in the orthogonal direction X is overlapped with the other irradiation locus within the range of the amplitude A and the laser beam LB is irradiated onto the overlapping portion 53.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for joining dissimilar metal plates, a joining apparatus, and a joined body. [Background technology]

[0002] Patent Document 1 discloses a technique for joining dissimilar metal plates made of different materials, such as copper and aluminum. In the technique disclosed in Patent Document 1, a laser beam is irradiated onto an overlapping portion of a first metal plate and a second metal plate, and a weld is formed in the overlapping portion by heating based on the laser beam irradiation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 6998630 Summary of the Invention [Problem to be solved by the invention]

[0004] When the irradiation trajectory of the laser beam on the overlapping portion of dissimilar metal plates is a trajectory that includes a non-linear region, such as a sinusoidal wave, it is difficult to maintain a constant moving speed of the irradiation position of the laser beam along the entire irradiation trajectory. In this case, the weld formed along the irradiation trajectory of the laser beam has a region with a small width and depth and a small weld volume, which may reduce the joining strength between the dissimilar metal plates.

[0005] An object of the present invention is to provide a method for joining dissimilar metal plates, a joining apparatus, and a joined body that can increase the joining strength between dissimilar metal plates. [Means for solving the problem]

[0006] According to one aspect of the present invention, a method for joining dissimilar metal plates is a method for joining a first metal plate and a second metal plate made of different materials. The method includes: an arrangement step of forming an overlapping portion where the first metal plate and the second metal plate are arranged to overlap each other; and a laser welding step of irradiating the overlapping portion with a laser beam and moving the irradiation position of the laser beam relative to the overlapping portion in a predetermined direction while reciprocating in an orthogonal direction perpendicular to the predetermined direction, thereby forming a weld in the overlapping portion along a sinusoidal irradiation locus having a predetermined amplitude in the orthogonal direction. In the laser welding step, a plurality of the irradiation loci are drawn spaced apart from each other in the orthogonal direction, and one of the irradiation loci overlaps with the other irradiation locus within the amplitude range of the other irradiation locus adjacent to the orthogonal direction as viewed in the predetermined direction, and the laser beam is irradiated onto the overlapping portion.

[0007] According to this method for joining dissimilar metal plates, a laser beam is irradiated onto the overlapping portion of the first metal plate and the second metal plate in a manner that traces a sinusoidal irradiation locus, and a weld is formed along the irradiation locus. The sinusoidal irradiation locus has, within the amplitude range of the sinusoidal wave, non-linear regions that are curved and include peaks or valleys, and linear regions that include the center of the wave and connect the non-linear regions. The movement speed of the laser beam irradiation position when tracing the irradiation locus is usually faster in the linear regions than in the non-linear regions. In this case, the width and depth of the weld formed along the irradiation locus of the laser beam are smaller in the linear regions than in the non-linear regions, and therefore the weld volume of the weld is smaller in the linear regions of the irradiation locus than in the non-linear regions. This may result in a decrease in the joint strength between the dissimilar metal plates, i.e., the first metal plate and the second metal plate.

[0008] Therefore, in the laser welding process, multiple irradiation loci are drawn at intervals in the orthogonal direction, and one irradiation locus is overlapped within the amplitude range of the other irradiation locus adjacent to the other in the orthogonal direction when viewed in a predetermined direction, and laser light is irradiated onto the overlapping portion. This makes it possible to overlap a non-linear region including the apex of a peak or valley of one irradiation locus with a linear region within the amplitude range of the other irradiation locus adjacent to the other in the orthogonal direction when viewed in the predetermined direction. Therefore, in each weld formed along the multiple irradiation loci, linear regions with small weld volumes can be reinforced with non-linear regions with large weld volumes when viewed in the predetermined direction. This makes it possible to increase the joint strength between the dissimilar metal plates, i.e., the first metal plate and the second metal plate.

[0009] In the above-mentioned method for joining dissimilar metal plates, in the laser welding step, the laser light may be irradiated onto the overlapping portion with three or more irradiation trajectories having the same amplitude, without shifting the phase, and with the pitch between the centers of the amplitudes being equal.

[0010] In this aspect, it is possible to more reliably overlap the non-linear region of one irradiation locus with the linear region within the amplitude range of the other irradiation locus that is adjacent in the orthogonal direction when viewed in a predetermined direction, so that in each weld formed along multiple irradiation loci, the linear region with a small weld volume can be more reliably reinforced with the non-linear region with a large weld volume when viewed in the predetermined direction.

[0011] In the above-mentioned method for joining dissimilar metal plates, in the laser welding step, when drawing a plurality of irradiation loci, the laser light may be irradiated onto the overlapping portion so that the second and subsequent irradiation loci are drawn alternately on one side and the other side of the orthogonal direction, based on the irradiation locus drawn the first time.

[0012] In this embodiment, when drawing multiple irradiation loci, the second and subsequent irradiation loci are drawn alternately on one side and the other side of the orthogonal direction based on the first irradiation locus. In this case, for example, the third irradiation locus is drawn adjacent to the first irradiation locus on the opposite side from the second irradiation locus. In other words, the third and subsequent irradiation loci are drawn adjacent to the irradiation locus drawn two irradiations ago. This allows the third and subsequent irradiation loci to be drawn in a state where the influence of heat generated by the irradiation of laser light is reduced. Therefore, it is possible to suppress uneven welding of the welded portion caused by the influence of heat generated by the irradiation of laser light.

[0013] In the above-described method for joining dissimilar metal plates, in the laser welding step, the laser light may be irradiated onto the overlapping portion so as to trace a plurality of irradiation loci in one direction from one side of the predetermined direction to the other side.

[0014] In this embodiment, multiple irradiation loci are drawn in one direction from one side to the other in a predetermined direction. In this case, compared to a case where an irradiation locus is drawn from one side to the other in a predetermined direction and then an irradiation locus is drawn from the other side to the first side in a turning back manner, each irradiation locus can be drawn at a time interval. This allows each irradiation locus to be drawn in a state where the influence of heat generated by the irradiation of the laser light is reduced. Therefore, it is possible to suppress uneven welding of the welded portion caused by the influence of heat generated by the irradiation of the laser light.

[0015] In the above-described method for joining dissimilar metal plates, in the laser welding step, a ratio of the amplitude to the pitch for the plurality of irradiation loci may be set in the range of 1.3 to 3.3.

[0016] In this aspect, by setting the ratio of amplitude to pitch in the range of 1.3 to 3.3 for the multiple irradiation loci, it is possible to more reliably overlap the non-linear region of one irradiation locus with the linear region within the amplitude range of the other irradiation locus that is adjacent in the orthogonal direction when viewed in a predetermined direction. Therefore, in each weld formed along the multiple irradiation loci, it is possible to more reliably reinforce the linear region with a small weld volume with the non-linear region with a large weld volume when viewed in the predetermined direction.

[0017] According to another aspect of the present invention, an apparatus for joining dissimilar metal plates is an apparatus for joining a first metal plate and a second metal plate made of different materials. The apparatus for joining dissimilar metal plates includes: a positioning unit for forming an overlapping portion where the first metal plate and the second metal plate are arranged overlapping each other; an oscillation unit for emitting a laser beam; and an irradiation unit for irradiating the overlapping portion with the laser beam emitted from the oscillation unit and forming a weld in the overlapping portion along a sinusoidal irradiation locus having a predetermined amplitude in the orthogonal direction by moving an irradiation position of the laser beam relative to the overlapping portion in a predetermined direction while reciprocating in an orthogonal direction perpendicular to the predetermined direction. The irradiation unit draws a plurality of irradiation loci spaced apart from each other in the orthogonal direction and irradiates the overlapping portion with the laser beam while overlapping one irradiation locus within the amplitude range of the other irradiation locus adjacent to the orthogonal direction as viewed in the predetermined direction.

[0018] According to another aspect of the present invention, a joined body of dissimilar metal plates is a joined body in which a first metal plate and a second metal plate made of different materials are joined together. This joined body of dissimilar metal plates includes an overlapping portion where the first metal plate and the second metal plate overlap each other, and a plurality of welds formed in the overlapping portion, extending in a predetermined direction and shaped along a sinusoidal waveform having a predetermined amplitude in an orthogonal direction perpendicular to the predetermined direction. The plurality of welds are spaced apart from each other in the orthogonal direction, and when viewed in the predetermined direction, the waveform of one of the welds adjacent to each other in the orthogonal direction overlaps within the amplitude range of the waveform of the other weld. [Effects of the Invention]

[0019] As described above, according to the present invention, it is possible to provide a method for joining dissimilar metal plates, a joining apparatus, and a joined body that are capable of increasing the joining strength between dissimilar metal plates. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view schematically illustrating a configuration of a joining device according to an embodiment of the present invention. [Figure 2] 1A to 1C are diagrams for explaining a joining method according to an embodiment of the present invention. [Figure 3] FIG. 3 is an enlarged view of a portion S in FIG. 2, showing an enlarged irradiation locus of a laser beam. [Figure 4] 10A and 10B are diagrams for explaining the relationship between amplitude and pitch in a plurality of irradiation loci. [Figure 5] 1A and 1B are diagrams illustrating a bonded structure according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, a method for joining dissimilar metal plates, a joining apparatus, and a joined body according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, with regard to directional relationships, a predetermined direction will be referred to as a predetermined direction Y, a direction perpendicular to the predetermined direction Y on a horizontal plane will be referred to as an orthogonal direction X, and a direction perpendicular to the predetermined direction Y and the orthogonal direction X will be referred to as a vertical direction Z.

[0022] [About the joining device] FIG. 1 is a perspective view showing a schematic configuration of a joining device 1 according to an embodiment of the present invention. The joining device 1 is a joining device for joining dissimilar metal plates, which joins a first metal plate 51 and a second metal plate 52 made of different materials. The joining device 1 irradiates an overlapping portion 53 where the first metal plate 51 and the second metal plate 52 overlap each other in the up-down direction Z with a laser beam LB, thereby locally melting and solidifying the overlapping portion 53 and joining the plates. When the laser beam LB is irradiated onto the overlapping portion 53, the overlapping portion 53 is locally melted by heating caused by the irradiation of the laser beam LB, and the melted portion solidifies, thereby joining the first metal plate 51 and the second metal plate 52.

[0023] The first metal plate 51 is a flat plate made of, for example, aluminum or an aluminum alloy and has a predetermined thickness. The second metal plate 52 is a flat plate made of, for example, copper or a copper alloy and has a predetermined thickness.

[0024] The bonding device 1 includes a placement unit 2, an oscillation unit 3, and an irradiation unit 4.

[0025] The arrangement unit 2 is a unit for forming an overlapping portion 53 where the first metal plate 51 and the second metal plate 52 are arranged to overlap each other in the vertical direction Z. When the first metal plate 51 and the second metal plate 52 are arranged in the arrangement unit 2, an overlapping portion 53 where the first metal plate 51 and the second metal plate 52 overlap is formed. In the overlapping portion 53 of the first metal plate 51 and the second metal plate 52, the second metal plate 52 may overlap the first metal plate 51, or the first metal plate 51 may overlap the second metal plate 52. In this embodiment, the overlapping portion 53 is formed where the second metal plate 52, which has high thermal conductivity, overlaps the first metal plate 51.

[0026] The oscillation unit 3 is a laser oscillator that oscillates laser light LB. The oscillation unit 3 oscillates, as the laser light LB, laser light selected from, for example, a CO2 laser, a YAG laser, a semiconductor laser, a fiber laser, and an LD-pumped solid-state laser.

[0027] The irradiation unit 4 is a unit that irradiates the laser light LB oscillated from the oscillation unit 3 onto the overlapping portion 53 of the first metal plate 51 and the second metal plate 52 arranged in the arrangement unit 2. The irradiation unit 4 forms a weld in the overlapping portion 53 while tracing an irradiation locus of a predetermined shape by moving the irradiation position of the laser light LB with respect to the overlapping portion 53 in a predetermined direction Y and reciprocating in an orthogonal direction X.

[0028] The irradiation unit 4 is configured, for example, by a galvanometer scanner. In this case, the irradiation unit 4 includes a first mirror 41, a second mirror 42, a condenser lens 43, an X-axis motor 44, a Y-axis motor 45, and a control driver 46. The first mirror 41 is a mirror that reflects the laser light LB oscillated from the oscillation unit 3 and is rotatable in response to driving of the X-axis motor 44. The first mirror 41 rotates in response to driving of the X-axis motor 44 to change the reflection direction of the laser light LB, thereby moving the irradiation position of the laser light LB on the overlapping portion 53 back and forth in the orthogonal direction X. The second mirror 42 is a mirror that reflects the laser light LB reflected by the first mirror 41 and is rotatable in response to driving of the Y-axis motor 45. The second mirror 42 rotates in response to driving of the Y-axis motor 45 to change the reflection direction of the laser light LB, thereby moving the irradiation position of the laser light LB on the overlapping portion 53 in the predetermined direction Y. The condensing lens 43 is a lens that condenses the laser light LB reflected by the second mirror 42 and guides it to the overlapping portion 53. The control driver 46 controls the X-axis motor 44 and the Y-axis motor 45 to move the irradiation position of the laser light LB with respect to the overlapping portion 53 in a predetermined direction Y while moving it back and forth in the orthogonal direction X.

[0029] [Joining method] 2 to 4, a method for joining dissimilar metal plates according to this embodiment will be described. The method for joining dissimilar metal plates is carried out using the above-described joining apparatus 1. The method for joining dissimilar metal plates includes an arrangement step and a laser welding step.

[0030] In the placement step, the first metal plate 51 and the second metal plate 52 are placed in the placement unit 2 so that they overlap each other to form an overlapping portion 53. The placement of the first metal plate 51 and the second metal plate 52 in the placement unit 2 may be performed automatically by the placement unit 2 or may be performed by an operator.

[0031] In the laser welding process, the irradiation unit 4 irradiates the upper surface of the overlapping portion 53 with the laser light LB oscillated from the oscillation unit 3. The irradiation unit 4 irradiates the upper surface of the overlapping portion 53 with the laser light LB through the condenser lens 43 based on the rotation of the first mirror 41 and the second mirror 42 in response to the control of the X-axis motor 44 and the Y-axis motor 45 by the control driver 46.

[0032] In the laser welding process, the irradiation unit 4 moves the irradiation position of the laser beam LB on the upper surface of the overlapping portion 53 in a predetermined direction Y while reciprocating in an orthogonal direction X, thereby forming a weld 6 in the overlapping portion 53 along a sinusoidal irradiation locus LL having a predetermined amplitude A in the orthogonal direction X. As shown in FIG. 3 , the sinusoidal irradiation locus LL represents a sine wave having a wavelength λ in the predetermined direction Y and an amplitude A in the orthogonal direction X, or a waveform similar to the sine wave, such as a triangular wave or a sawtooth wave. In addition, in this embodiment, the amplitude A of the irradiation locus LL is defined as the distance from the peak to the valley of the sinusoidal waveform. In other words, the range of the amplitude A of the irradiation locus LL is the range from the peak to the valley of the sinusoidal waveform.

[0033] In the laser welding process, the irradiation unit 4 irradiates the overlapping portion 53 between the first metal plate 51 and the second metal plate 52 with laser light LB to trace a sinusoidal irradiation locus LL, forming a weld 6 along the irradiation locus LL. As shown in FIG. 3 , the sinusoidal irradiation locus LL has, within the range of the amplitude A of the sinusoidal wave, a non-linear region B1 that is a curved region including peaks or valleys, and a linear region B2 that is a straight line that includes the center of the amplitude A (the center of the wave) and connects the non-linear regions B1. When tracing the irradiation locus LL, the laser light LB typically moves faster in the linear region B2 than in the non-linear region B1. In this case, the width W and depth of the weld 6 formed along the irradiation locus LL of the laser light LB are smaller in the linear region B2 than in the non-linear region B1. Therefore, the weld volume of the weld 6 is smaller in the linear region B2 than in the non-linear region B1 on the irradiation locus LL (see the cross-sectional view in FIG. 3 ). Therefore, there is a risk that the bonding strength between the first metal plate 51 and the second metal plate 52, which are dissimilar metal plates, may decrease.

[0034] Therefore, the irradiation unit 4 draws multiple irradiation loci LL spaced apart from each other in the orthogonal direction X, and irradiates the overlapping portion 53 with laser light LB, overlapping a non-linear region B1 including the apex of a peak or valley of one irradiation locus LL within the range of the amplitude A of the other irradiation locus LL adjacent to the orthogonal direction X as viewed in the predetermined direction Y. This allows the non-linear region B1 including the apex of a peak or valley of one irradiation locus LL to overlap a linear region B2 within the range of the amplitude A of one irradiation locus LL adjacent to the orthogonal direction X as viewed in the predetermined direction Y. Therefore, in each weld 6 formed along the multiple irradiation loci LL, the linear region B2 with a small weld volume can be reinforced with the non-linear region B1 with a large weld volume as viewed in the predetermined direction. This increases the joint strength between the first metal plate 51 and the second metal plate 52, which are dissimilar metal plates.

[0035] In the present embodiment, in the laser welding process, the irradiation unit 4 irradiates the overlapping portion 53 with laser light LB so that three or more irradiation loci LL having the same amplitude A are drawn without phase shift and at an equal pitch P between the centers (wave centers) of the amplitudes A. In the example of Fig. 3, the irradiation unit 4 irradiates the overlapping portion 53 with laser light LB so that three irradiation loci: a first irradiation locus LL1, a second irradiation locus LL2, and a third irradiation locus LL3 having the same amplitude A are drawn at an equal pitch P apart from each other in the orthogonal direction X without phase shift. The irradiation unit 4 draws a second irradiation locus LL2 at a position adjacent to one side X1 of the orthogonal direction X to the first irradiation locus LL1, and a third irradiation locus LL3 at a position adjacent to the other side X2 of the orthogonal direction X to the first irradiation locus LL1. In this case, it is possible to more reliably overlap the non-linear regions B1 of the second irradiation locus LL2 and the third irradiation locus LL3 with the linear region B2 within the range of the amplitude A of the first irradiation locus LL1 when viewed in the predetermined direction Y. Therefore, when the weld 6 formed along the first irradiation locus LL1 is defined as the first weld 61, the weld 6 formed along the second irradiation locus LL2 is defined as the second weld 62, and the weld 6 formed along the third irradiation locus LL3 is defined as the third weld 63, it is possible to more reliably reinforce the linear region B2 with a small weld volume in the first weld 61 with the non-linear regions B1 with a large weld volume in the second weld 62 and the third weld 63 when viewed in the predetermined direction Y.

[0036] As shown in FIG. 4, in the laser welding process, the irradiation unit 4 sets the ratio (A / P) of the amplitude A to the pitch P for the multiple irradiation loci LL, namely, the first irradiation locus LL1, the second irradiation locus LL2, and the third irradiation locus LL3, to a range of 1.3 or more and 3.3 or less.

[0037] By setting the ratio (A / P) of the amplitude A to the pitch P to 1.3 or more, it is possible to overlap at least a part of the non-linear region B1 of the second irradiation locus LL2 and the third irradiation locus LL3 with the linear region B2 within the range of the amplitude A of the first irradiation locus LL1 when viewed in the predetermined direction Y. If the ratio (A / P) of the amplitude A to the pitch P is set to less than 1.3, it may not be possible to effectively overlap the non-linear region B1 of the second irradiation locus LL2 and the third irradiation locus LL3 with the linear region B2 within the range of the amplitude A of the first irradiation locus LL1.

[0038] By setting the ratio (A / P) of the amplitude A to the pitch P to 3.3 or less, it is possible to make the non-linear regions B1 of the second irradiation locus LL2 and the third irradiation locus LL3 overlap the linear region B2 within the range of the amplitude A of the first irradiation locus LL1 when viewed in the predetermined direction Y, and to prevent the linear regions B2 of the second irradiation locus LL2 and the third irradiation locus LL3 from overlapping. If the ratio (A / P) of the amplitude A to the pitch P exceeds 3.3, the linear regions B2 of the second irradiation locus LL2 and the third irradiation locus LL3 may overlap to a large extent with the linear region B2 within the range of the amplitude A of the first irradiation locus LL1.

[0039] As described above, the irradiation unit 4 sets the ratio (A / P) of the amplitude A to the pitch P in the first irradiation locus LL1, the second irradiation locus LL2, and the third irradiation locus LL3 as the multiple irradiation loci LL to a range of 1.3 to 3.3. This makes it possible to more reliably overlap the non-linear regions B1 of the second irradiation locus LL2 and the third irradiation locus LL3 with the linear region B2 within the range of the amplitude A of the first irradiation locus LL1 when viewed in the predetermined direction Y. Therefore, in the first welded portion 61, the second welded portion 62, and the third welded portion 63 formed along the first irradiation locus LL1, the second irradiation locus LL2, and the third irradiation locus LL3, when viewed in the predetermined direction Y, the linear region B2 with a small weld volume in the first welded portion 61 can be more reliably reinforced with the non-linear regions B1 with a large weld volume in the second welded portion 62 and the third welded portion 63. This makes it possible to increase the joint strength between the first metal plate 51 and the second metal plate 52, which are dissimilar metal plates.

[0040] When drawing multiple irradiation loci LL in the overlapping portion 53, as shown in FIG. 3 , the irradiation unit 4 irradiates the overlapping portion 53 with laser light LB so as to sequentially draw second and subsequent irradiation loci LL alternately on one X1 side and the other X2 side of the orthogonal direction X, based on the first irradiation locus LL drawn as a reference. For example, when drawing three irradiation loci, a first irradiation locus LL1, a second irradiation locus LL2, and a third irradiation locus LL3, in the overlapping portion 53, the irradiation unit 4 draws a second irradiation locus LL2 on one X1 side of the orthogonal direction X, based on the first irradiation locus LL1 drawn as a reference, and a third irradiation locus LL3 on the other X2 side of the orthogonal direction X. In this case, for example, the third irradiation locus LL3 is drawn adjacent to the first irradiation locus LL1 drawn as a reference, on the opposite side of the second irradiation locus LL2 drawn as a reference. In other words, the third and subsequent irradiation loci LL are drawn adjacent to the irradiation locus LL drawn two times before. This allows the third and subsequent irradiation loci LL to be drawn in a state in which the influence of heat generated by the irradiation of the laser beam LB is reduced. This makes it possible to suppress uneven welding of the welded portion 6 caused by the influence of heat generated by the irradiation of the laser beam LB. This makes it possible to increase the joint strength between the dissimilar metal plates, the first metal plate 51 and the second metal plate 52.

[0041] Note that the welding unevenness of the welded portion 6 due to the influence of heat generated by the irradiation of the laser beam LB includes welding unevenness due to the thickness of the layer of intermetallic compounds generated in the welded portion 6. When the first metal plate 51 is made of aluminum and the second metal plate 52 is made of copper, examples of intermetallic compounds generated in the welded portion 6 include Cu9Al4, CuAl, and CuAl2. It is generally known that the strength of such intermetallic compounds is greatest for Cu9Al4, least for CuAl2, and intermediate for CuAl. Therefore, if the thickness of the layer of CuAl2 generated in the welded portion 6 due to the influence of heat generated by the irradiation of the laser beam LB is large, the bonding strength between the dissimilar metal plates, i.e., the first metal plate 51 and the second metal plate 52, may be reduced. Therefore, when drawing multiple irradiation loci LL in the overlapping portion 53, it is necessary to minimize the influence of heat generated by the irradiation of the laser beam LB.

[0042] In the laser welding process, the irradiation unit 4 irradiates the overlapping portion 53 with laser light LB to draw multiple irradiation loci LL in one direction from one side Y1 to the other side Y2 of the predetermined direction Y. For example, when drawing three irradiation loci, a first irradiation locus LL1, a second irradiation locus LL2, and a third irradiation locus LL3, in the overlapping portion 53, the irradiation unit 4 draws all of the first irradiation locus LL1, the second irradiation locus LL2, and the third irradiation locus LL3 in one direction from one side Y1 to the other side Y2 of the predetermined direction Y.

[0043] In this case, compared to drawing a first irradiation locus LL1 from one side Y1 to the other side Y2 of the predetermined direction Y, drawing a second irradiation locus LL2 from the other side Y2 to the other side Y1 in a turning manner, and then drawing a third irradiation locus LL3 from the one side Y1 to the other side Y2 in a turning manner, the first irradiation locus LL1, the second irradiation locus LL2, and the third irradiation locus LL3 can be drawn at time intervals. This allows the first irradiation locus LL1, the second irradiation locus LL2, and the third irradiation locus LL3 to be drawn in a state where the influence of heat generated by the irradiation of the laser beam LB is reduced. This prevents uneven welding of the welded portion 6 due to the influence of heat generated by the irradiation of the laser beam LB. This increases the joint strength between the first metal plate 51 and the second metal plate 52, which are dissimilar metal plates.

[0044] [About the zygote] A joined body 7 of dissimilar metal plates according to this embodiment will be described with reference to Fig. 5. The joined body 7 of dissimilar metal plates is produced by a joining method using the above-described joining apparatus 1. The joined body 7 is a joined body of dissimilar metal plates in which a first metal plate 51 and a second metal plate 52 made of different materials are joined together.

[0045] The joined body 7 includes an overlapping portion 53 where a first metal plate 51 and a second metal plate 52 overlap each other, and a plurality of welds 6 formed in the overlapping portion 53. The plurality of welds 6 extend in a predetermined direction Y on the upper surface of the overlapping portion 53 and have a shape that follows a sinusoidal waveform having a predetermined amplitude A in an orthogonal direction X that is perpendicular to the predetermined direction Y. The plurality of welds 6 are spaced apart from each other in the orthogonal direction X, and when viewed in the predetermined direction Y, the waveform of one weld 6 adjacent to the other weld 6 overlaps within the range of the amplitude A of the waveform of the other weld 6. This increases the joining strength between the dissimilar metal plates, the first metal plate 51 and the second metal plate 52, in the joined body 7.

[0046] In this embodiment, in the joined body 7, a plurality of welds 6 shaped along three or more sinusoidal waveforms with the same amplitude A are formed in the overlapping portion 53 without phase shift and with equal intervals between the centers of the amplitudes A. In the example of FIG. 5 , in the joined body 7, a first weld 61, a second weld 62, and a third weld 63 shaped along three sinusoidal waveforms with the same amplitude A are formed in the overlapping portion 53 at equal intervals in the orthogonal direction X without phase shift. On the upper surface of the overlapping portion 53, the second weld 62 is formed at a position adjacent to the first weld 61 on one side X1 of the orthogonal direction X, and the third weld 63 is formed at a position adjacent to the first weld 61 on the other side X2 of the orthogonal direction X. In the first weld 61, the second weld 62, and the third weld 63 formed on the upper surface of the overlapping portion 53, the ratio of the amplitude A to the pitch P (A / P) is set to a range of 1.3 to 3.3. As a result, in the bonded body 7, the bonding strength between the dissimilar metal plates, that is, the first metal plate 51 and the second metal plate 52, is more reliably increased.

[0047] [Modified embodiment] Although the embodiment of the present invention has been described above, the present invention is not limited to this and may take the following modified embodiments, for example.

[0048] In the above embodiment, an example has been described in which the irradiation unit 4 of the bonding apparatus 1 is configured with a galvanometer scanner, but the configuration is not limited to this. The irradiation unit 4 may be configured to move the irradiation position of the laser light LB on the overlapping portion 53 in the predetermined direction Y while reciprocating in the orthogonal direction X. For example, the arrangement unit 2 on which the first metal plate 51 and the second metal plate 52 are arranged may be configured to be movable in the predetermined direction Y, and the irradiation unit 4 may be configured to swing in the orthogonal direction X in accordance with the movement of the arrangement unit 2. In this case, the irradiation position of the laser light LB on the overlapping portion 53 moves in the predetermined direction Y in accordance with the movement of the arrangement unit 2, while moving reciprocating in the orthogonal direction X in accordance with the swing of the irradiation unit 4. [Explanation of symbols]

[0049] 1 Bonding equipment 2 Placement Units 3 Oscillator unit 4 Irradiation Unit 51 1st metal plate 52 Second metal plate 53 Overlapping part 6 Welded parts 61 First Welding Section 62 Second Welding Section 63 Third Welding Section 7 Zygote LB laser light LL irradiation trajectory LL1 1st irradiation trajectory LL2 2nd irradiation trajectory LL3 3rd irradiation trajectory X orthogonal direction Y specified direction

Claims

1. A method for joining dissimilar metal plates, which joins a first metal plate and a second metal plate made of different materials, an arrangement step of forming an overlapping portion in which the first metal plate and the second metal plate are arranged to overlap each other; a laser welding process of irradiating the overlapping portion with laser light, and moving an irradiation position of the laser light on the overlapping portion in a predetermined direction while reciprocating in an orthogonal direction perpendicular to the predetermined direction, thereby forming a weld in the overlapping portion along a sinusoidal irradiation locus having a predetermined amplitude in the orthogonal direction, In the laser welding process, a plurality of the irradiation loci are drawn at intervals in the orthogonal direction, and when viewed in the predetermined direction, one of the irradiation loci adjacent to the other in the orthogonal direction is overlapped within the range of the amplitude of the other irradiation locus, and the laser light is irradiated onto the overlapping portion.

2. 2. The method for joining dissimilar metal plates according to claim 1, wherein in the laser welding step, the laser beam is irradiated onto the overlapping portion of three or more of the irradiation loci having the same amplitude, without shifting their phases, with the centers of the amplitudes spaced at equal intervals.

3. 3. The method for joining dissimilar metal plates according to claim 2, wherein in the laser welding step, when a plurality of the irradiation loci are drawn, the laser light is irradiated onto the overlapping portion so that the second and subsequent irradiation loci are drawn alternately on one side and the other side of the orthogonal direction based on the irradiation locus drawn a first time.

4. 3. The method for joining dissimilar metal plates according to claim 2, wherein in the laser welding step, the laser light is irradiated onto the overlapping portion so as to trace a plurality of irradiation loci in one direction from one side of the predetermined direction to the other side.

5. 3. The method for joining dissimilar metal plates according to claim 2, wherein in the laser welding step, a ratio of the amplitude to the pitch for the plurality of irradiation loci is set in a range of 1.3 to 3.

3.

6. A dissimilar metal plate joining device that joins a first metal plate and a second metal plate made of different materials, a positioning unit for forming an overlapping portion where the first metal plate and the second metal plate are arranged to overlap each other; an oscillation unit that emits laser light; an irradiation unit that irradiates the overlapping portion with the laser light oscillated from the oscillation unit, and moves the irradiation position of the laser light on the overlapping portion in a predetermined direction while reciprocating in an orthogonal direction perpendicular to the predetermined direction, thereby forming a welded portion in the overlapping portion along a sinusoidal irradiation locus having a predetermined amplitude in the orthogonal direction, the irradiation unit draws a plurality of irradiation loci spaced apart from each other in the orthogonal direction, and overlaps one irradiation locus within the amplitude range of the other irradiation locus adjacent to the other in the orthogonal direction when viewed in the predetermined direction, and irradiates the laser light onto the overlapping portion.

7. A joint of dissimilar metal plates in which a first metal plate and a second metal plate made of different materials are joined, an overlapping portion where the first metal plate and the second metal plate overlap each other; a plurality of welds formed in the overlapping portion, extending in a predetermined direction and shaped along a sinusoidal waveform having a predetermined amplitude in a direction perpendicular to the predetermined direction; The plurality of welds are spaced apart from one another in the orthogonal direction, and when viewed in the predetermined direction, the waveform of one of the welds adjacent to each other in the orthogonal direction overlaps within the range of the amplitude of the waveform of the other weld.

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