Laser welding machine and laser welding method

Abstract

The present invention provides a laser welding method in which the laser beam does not enter the gap between a pair of flat wires and burn out the coating. [Solution] In the first step, the tip of the first flat wire 71L is melted by irradiating the center of the first tip surface of the first flat wire 71L with the first laser beam LB, thereby forming a first molten portion 72L on the first flat wire 71L. In the second step, the tip of the second flat wire 71R is melted by irradiating the center of the second tip surface of the second flat wire 71R with the second laser beam LB, thereby forming a second molten portion 72R on the second flat wire 71R. The irradiation start position of the third laser beam LB is set to a position on the surface of the second molten portion 72R that is shifted outward from the center of the second tip surface. In the third step, the third laser beam LB is moved from the irradiation start position toward the first molten portion 72L.

Description

Technical Field

[0001] The present invention relates to a laser welding machine and a laser welding method.

Background Art

[0002] In a motor used in an electric vehicle or a hybrid vehicle, both ends of segment coils bent in a U-shape and mounted on a core and adjacent in the radial direction are welded by a laser welding machine (see Patent Document 1). Both ends of the segment coils adjacent in the radial direction are a pair of straight lines.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The segment coils are coated for insulation, and the coating is removed to weld a pair of straight lines. There is a gap formed by the removal of the coating between the pair of straight lines. The laser welding machine irradiates laser beams on each tip surface of the pair of straight lines to melt each tip portion and weld between the tip portions of the pair of straight lines. When the laser beam enters the gap between the pair of straight lines when welding the tip portions of the pair of straight lines, the coating is burned and welding defects occur. There is a need for the emergence of a laser welding machine and a laser welding method that can weld a pair of straight lines well without the laser beam entering the gap between the pair of straight lines and burning the coating.

Means for Solving the Problems

[0005] A first aspect of one or more embodiments comprises a laser oscillator that emits a laser beam, a transmission fiber that transmits the laser beam emitted from the laser oscillator, a collimating lens that converts the divergent laser beam emitted from the exit end of the transmission fiber into collimated light, a focusing lens that focuses the collimated laser beam and irradiates a pair of adjacent rectangular wires to be welded, a processing head having a displacement mechanism that displaces the laser beam irradiated onto the pair of rectangular wires, and a control device that controls the emission of the laser beam by the laser oscillator and the displacement of the laser beam by the displacement mechanism, wherein the control device irradiates the first laser beam onto the center of the first tip surface of a first rectangular wire, which is one of the pair of rectangular wires. The present invention provides a laser welding machine that controls the laser oscillator and the displacement mechanism to melt the tip of the first flat wire and form a first molten portion on the first flat wire, and controls the laser oscillator and the displacement mechanism to melt the tip of the second flat wire by irradiating the center of the second tip surface of the second flat wire, which is the other of the pair of flat wires, and form a second molten portion on the second flat wire, and controls the laser oscillator and the displacement mechanism to move the third laser beam from the irradiation start position toward the first molten portion, with the irradiation start position of the third laser beam being set as the irradiation start position for the third laser beam, which is set as the irradiation start position, which is set as the irradiation start position, which is set as the irradiation start position, which is set as the irradiation start position, which is set as the irradiation start position, which is set as the irradiation start position, and moves the third laser beam toward the first molten portion.

[0006] A second aspect of one or more embodiments provides a laser welding method comprising: a first step of irradiating the center of the first tip face of a first flat wire, which is one of a pair of flat wires to be welded adjacent to each other, with a first laser beam to melt the tip of the first flat wire and form a first molten portion on the first flat wire; a second step of irradiating the center of the second tip face of the second flat wire, which is the other of the pair of flat wires, with a second laser beam to melt the tip of the second flat wire and form a second molten portion on the second flat wire; and a third step of moving a third laser beam from the irradiation start position toward the first molten portion, with the irradiation start position of the third laser beam being set as the irradiation start position for the third laser beam, which corresponds to a position on the surface of the second molten portion that is shifted outward from the center of the second tip face opposite to the first tip face. [Effects of the Invention]

[0007] According to one or more embodiments of the laser welding machine and laser welding method, a pair of flat wires can be successfully welded without the laser beam entering the gap between the pair of flat wires and burning off the coating. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example configuration of a laser processing machine according to one or more embodiments. [Figure 2] Figure 2 is a perspective view showing a galvanoscanner that may be included in a laser processing machine according to one or more embodiments. [Figure 3] Figure 3 is a side view showing the first step of a laser welding method according to one or more embodiments. [Figure 4] Figure 4 is a plan view showing a first step of a laser welding method according to one or more embodiments. [Figure 5] Figure 5 is a side view showing a second step of a laser welding method according to one or more embodiments. [Figure 6]Figure 6 is a plan view showing a second step of a laser welding method according to one or more embodiments. [Figure 7] Figure 7 is a side view showing a third step of a laser welding method according to one or more embodiments. [Figure 8] Figure 8 is a plan view showing a third step of a laser welding method according to one or more embodiments. [Figure 9] Figure 9 shows preferred irradiation start and end positions of the laser beam in the third step of a laser welding method according to one or more embodiments. [Figure 10] Figure 10 shows the relationship between the irradiation start position of the laser beam and the direction in which metal vapor is ejected in the third step of a laser welding method according to one or more embodiments. [Figure 11] Figure 11 is a side view showing a fourth step of a laser welding method according to one or more embodiments. [Figure 12] Figure 12 is a plan view showing a fourth step of a laser welding method according to one or more embodiments. [Figure 13] Figure 13 shows a fixed-point irradiation or laser beam wobbling that can be performed in the first or second step. [Figure 14] Figure 14 shows the linear or wobbling movement of the laser beam that can be performed in the third step. [Figure 15] Figure 15 shows the laser beam wobbling that can be performed in the fourth step. [Figure 16] Figure 16 is a photograph used as a substitute for a drawing, showing a pair of flat wires before welding. [Figure 17] Figure 17 is a photograph used as a substitute for a drawing, showing the state of a pair of rectangular wires in the first process. [Figure 18] Figure 18 is a photograph used as a substitute for a drawing, showing the state of a pair of rectangular wires in the second process. [Figure 19] Figure 19 is a photographic representation of the state of a pair of rectangular wires in the third step. [Figure 20] FIG. 20 is a drawing substitute photograph showing the state of a pair of straight angles in the fourth step.

Embodiments for Carrying out the Invention

[0009] Hereinafter, a laser welding machine and a laser welding method according to one or more embodiments will be described with reference to the accompanying drawings. First, a laser welding machine 100 according to one or more embodiments for welding a pair of straight angles will be described using FIGS. 1 and 2. The laser welding machine 100 shown in FIG. 1 executes a laser welding method according to one or more embodiments.

[0010] As shown in FIG. 1, the laser welding machine 100 includes an NC device 10, a blue laser oscillator 20, a transmission fiber 30, a processing head 40, and a camera 50. The NC device 10 is an example of a control device that controls each part of the laser welding machine 100. The blue laser oscillator 20 emits a blue laser beam having a wavelength of, for example, 400 nm or more and 460 nm or less. The transmission fiber 30 transmits the laser beam indicated by the dashed line射出 from the blue laser oscillator 20 to the processing head 40.

[0011] The processing head 40 has a collimating lens 41, a galvanometer scanner 42, and a focusing lens 43. The collimating lens 41 converts the divergent laser beam射出 from the emission end of the transmission fiber 30 into collimated light. The laser beam of the collimated light enters the focusing lens 43 via the galvanometer scanner 42 described later. The focusing lens 43 focuses the laser beam of the collimated light and irradiates the laser beam onto a pair of straight angles 71L and 71R to be welded. The laser beam射出 from the focusing lens 43 and irradiated onto the pair of straight angles 71L and 71R will be referred to as the laser beam LB.

[0012] Below the processing head 40, multiple pairs of coated copper wires 61L and 61R are arranged. The ends of the coated copper wires 61L and 61R are flat rectangular wires 71L and 71R from which the coating has been removed. Typically, the coating is enamel coating. Gaps exist between the flat rectangular wires 71L and 71R due to the removal of the coating. As an example, multiple pairs of coated copper wires 61L and 61R (flat rectangular wires 71L and 71R) are arranged circumferentially and configured to rotate circumferentially. The processing head 40 can sequentially weld multiple pairs of flat rectangular wires 71L and 71R.

[0013] Camera 50 photographs multiple pairs of rectangular wires 71L and 71R and supplies the captured images to the NC device 10. Therefore, the NC device 10 can detect the position of each pair of rectangular wires 71L and 71R based on the captured images. Based on the detected positions of each pair of rectangular wires 71L and 71R, the NC device 10 sequentially moves the coated copper wires 61L and 61R in the circumferential direction and controls the emission of a laser beam from the blue laser oscillator 20 to weld each pair of rectangular wires 71L and 71R. The welded rectangular wires 71L and 71R are connected by a bridge 74. How the bridge 74 is formed will be described in detail later.

[0014] As shown in Figure 2, the galvanoscanner 42 includes a first galvano mirror 421, a first galvano motor 422 that drives the first galvano mirror 421, a second galvano mirror 423, and a second galvano motor 424 that drives the second galvano mirror 423. The laser beam emitted from the collimating lens 41 is incident on the first galvano mirror 421, reflected, and incident on the second galvano mirror 423. The laser beam is reflected by the second galvano mirror 423 and incident on the focusing lens 43.

[0015] The NC device 10 controls the first galvanometer motor 422 and the second galvanometer motor 424 to rotate the first galvanometer mirror 421 and the second galvanometer mirror 423 within a predetermined angular range. By rotating one or both of the first galvanometer mirror 421 and the second galvanometer mirror 423, the NC device 10 can displace or vibrate the laser beam.

[0016] The galvanoscanner 42 displaces the laser beam of collimated light emitted from the collimating lens 41 and directs it into the focusing lens 43. The galvanoscanner 42 is an example of a displacement mechanism that displaces the laser beam when irradiating the laser beam LB, which has been focused by the focusing lens 43, onto the flat rectangular wires 71L and 71R. By continuously displacing the laser beam LB, the galvanoscanner 42 can vibrate the laser beam LB in any pattern.

[0017] While it is not essential for the laser welding machine 100 to be equipped with a galvanometer scanner 42 as a displacement mechanism, a galvanometer scanner 42 is preferred as such. When the laser welding machine 100 is equipped with a galvanometer scanner 42, the laser beam can be displaced at high speed during welding of each pair of rectangular wires 71L and 71R. Furthermore, when the laser welding machine 100 is equipped with a galvanometer scanner 42, the laser beam can be displaced more precisely compared to a mechanism that displaces the processing head 40 itself.

[0018] In Figure 1, the shielding gas injection nozzles that blow shielding gas onto each pair of rectangular wires 71L and 71R during welding, and the shielding gas supply device that supplies shielding gas to the shielding gas injection nozzles are omitted from the illustration. The laser welding machine 100 may be equipped with an infrared laser oscillator that emits, for example, an infrared laser beam with a wavelength of 1060 nm to 1090 nm instead of a blue laser oscillator 20, and may be configured to weld the rectangular wires 71L and 71R with an infrared laser beam. The laser welding machine 100 may be equipped with both a blue laser oscillator 20 and an infrared laser oscillator, and may be configured to weld the rectangular wires 71L and 71R with a superimposed laser beam obtained by superimposing a blue laser beam and an infrared laser beam on each other.

[0019] A laser welding method for welding flat wires 71L and 71R using a laser welding machine 100 will be specifically described using Figures 3 to 20. The laser welding method includes at least the first to third steps, and preferably the first to fourth steps. Of the multiple pairs of flat wires 71L and 71R, the pair of flat wires 71L and 71R to be welded is located directly below the processing head 40. Figures 3 and 4 show the first step of the laser welding method. Figure 3 is a side view of the flat wires 71L and 71R, and Figure 4 is a top view of the flat wires 71L and 71R. In Figure 4, Bs indicates the beam spot of the laser beam LB.

[0020] As shown in Figures 3(a) and 4(a), the laser welding machine 100 irradiates the center of the tip surface 71La (first tip surface) of one of a pair of adjacent flat wires 71L and 71R to be welded, for example, the tip surface 71La (first tip surface) of the flat wire 71L (first flat wire). At this time, the NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to irradiate the center of the tip surface 71La of the flat wire 71L with the laser beam LB.

[0021] As a result, the tip of the rectangular wire 71L melts, and a first molten portion 72L is formed on the rectangular wire 71L, as shown in Figure 3(b) and Figure 4(b). As shown in Figure 3(a), the focal point of the laser beam LB is positioned slightly above the tip surface 71La, but this is not limited to this position. Note that "molten portion" refers to the part obtained as a result of the metal melting. In Figure 3(b) and Figure 4(b), the tip surface 71La shown in Figure 3(a) and Figure 4(a) does not exist because the tip of the rectangular wire 71L has melted. In Figure 4(b), the position of the tip surface 71La is shown virtually.

[0022] Figures 5 and 6 show the second step of the laser welding method. Figure 5 is a side view of the rectangular wires 71L and 71R, and Figure 6 is a top view of the rectangular wires 71L and 71R. The NC device 10 controls the galvanoscanner 42 to move the position from which the laser beam LB is irradiated from the tip surface 71La of the rectangular wire 71L to the tip surface 71Ra of the rectangular wire 71R. As shown in Figures 5(a) and 6(a), the laser welding machine 100 irradiates the center of the tip surface 71Ra (second tip surface) of the rectangular wire 71R (second rectangular wire), which is the other of the pair of rectangular wires 71L and 71R, with the laser beam LB (second laser beam). At this time, the NC device 10 controls the blue laser oscillator 20 and the galvanoscanner 42 to irradiate the center of the tip surface 71Ra of the rectangular wire 71R with the laser beam LB.

[0023] As a result, the tip of the rectangular wire 71R melts, and a second molten portion 72R is formed on the rectangular wire 71R, as shown in Figure 5(b) and Figure 6(b). A gap may exist between the first molten portion 72L and the second molten portion 72R. In Figure 5(b) and Figure 6(b), the tip surface 71Ra shown in Figure 5(a) and Figure 6(a) does not exist because the tip of the rectangular wire 71R has melted. In Figure 6(b), the position of the tip surface 71Ra is virtually shown.

[0024] Figures 7 and 8 show the third step of the laser welding method. The irradiation start position of the laser beam LB (third laser beam) is set to a position on the surface of the second molten part 72R that is shifted outward from the center of the tip surface 71Ra, opposite to the tip surface 71La. As shown in Figures 7(a) to 7(c), the NC device 10 controls the galvanometer scanner 42 to move the laser beam LB from the irradiation start position toward the first molten part 72L. As shown in Figures 7(b) and 8(b), in the third step, a portion of the molten metal of the second molten part 72R, which has been melted by the irradiation of the laser beam LB, moves toward the first molten part 72L. As a result, as shown in Figures 7(c) and 8(c), a bridge 73 connecting the first molten part 72L and the second molten part 72R is formed in the third step.

[0025] In the third step, once the bridge 73 is formed, the irradiation end position of the laser beam LB can be any position. Since the bridge 73 is formed when the laser beam LB is moved from the irradiation start position toward the first molten portion 72L and the laser beam LB is still irradiating the second molten portion 72R, the irradiation end position can be any position on the second molten portion 72R. To more reliably form the bridge 73, the irradiation end position may be any position on the surface of the second molten portion 72R that corresponds to a position on the tip surface 71La side of the tip surface 71Ra.

[0026] The irradiation end position may be any position on the surface of the first molten portion 72L. When the laser beam LB is moved to the first molten portion 72L, the first molten portion 72L also melts, thus further ensuring the formation of the bridge 73. In the example shown in Figure 7(c), the irradiation end position is set to a position on the surface of the first molten portion 72L corresponding to the center of the tip surface 71La. The irradiation end position may also be any position corresponding to the center of the tip surface 71La.

[0027] In this manner, the NC device 10 controls the galvanometer scanner 42 to move the laser beam LB from the irradiation start position toward the first molten portion 72L, using a position on the surface of the second molten portion 72R that corresponds to a position shifted outward from the center of the tip surface 71Ra, opposite to the tip surface 71La.

[0028] As shown in Figure 9, let X be the length of the side perpendicular to the direction in which the laser beam LB moves on the tip surfaces 71La and 71Ra, and Y be the length of the side parallel to the direction in which the laser beam LB moves. The irradiation start position on the surface of the second molten section 72R is preferably the position corresponding to the center of the perpendicular side on the tip surface 71Ra, and shifted outward by a distance of Y / 4 from the center of the parallel side (i.e., the position shifted outward by a distance of Y / 4 from the center of the tip surface 71Ra). The irradiation end position on the surface of the first molten section 72L is preferably the position corresponding to the center of the perpendicular side on the tip surface 71La, and shifted outward by a distance of Y / 4 from the center of the parallel side (i.e., the center of the tip surface 71La).

[0029] By the way, welding in the first to third processes is welding that generates metal vapor. The NC device 10 controls the blue laser oscillator 20 to generate metal vapor from the flat wire 71L, the flat wire 71R, and the second molten section 72R by irradiating the surface of each of these surfaces with a laser beam LB. The blue laser oscillator 20 emits a laser beam with sufficient laser power to generate metal vapor from the flat wire 71L, the flat wire 71R, and the second molten section 72R.

[0030] As shown in Figure 10(a), suppose the laser beam LB is irradiated onto the second molten section 72R, with the irradiation start position set to a position corresponding to the center of the tip surface 71Ra on the surface of the second molten section 72R. Since the molten metal vapor Vp in the second molten section 72R is ejected upward, almost none of the molten metal in the second molten section 72R moves to the first molten section 72L. In contrast, as shown in Figure 10(b), if the laser beam LB is irradiated onto the second molten section 72R with the irradiation start position set to a position shifted outward from the center of the tip surface 71Ra on the surface of the second molten section 72R, the metal vapor Vp is biased outward and ejected diagonally upward. As a result, the molten metal in the second molten section 72R can be moved to the first molten section 72L.

[0031] The metal vapor Vp ejected outward and diagonally upward causes the molten metal in the second molten section 72R to move to the first molten section 72L, forming a bridge 73 that connects the first molten section 72L and the second molten section 72R. Therefore, it can be understood that in the third step, the irradiation end position of the laser beam LB does not necessarily have to be on the first molten section 72L.

[0032] Figures 11 and 12 show the fourth step of the laser welding method. As shown in Figure 11(a) and Figure 12, the laser welding machine 100 irradiates the surface of the bridge 73 with a laser beam LB (the fourth laser beam). At this time, the NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to irradiate the surface of the bridge 73 with the laser beam LB.

[0033] Then, as shown in Figure 11(b), the amount of molten metal as bridge 73 increases, or the shape of bridge 73 is refined, and the final bridge 74 is formed. Providing a fourth step is not essential, but it is preferable. The welding in the fourth step is also a welding process that generates metal vapor. By providing a fourth step, a predetermined molten shape can be stably formed.

[0034] As shown in Figure 12, the beam spot Bs is positioned approximately in the center of the bridge 73, but as will be described later, the NC device 10 may control the galvanoscanner 42 to move the position from which the laser beam LB is irradiated.

[0035] In the example described above, in the first step, the laser beam LB is irradiated onto the tip surface 71La of the flat wire 71L, and in the second step, the laser beam LB is irradiated onto the tip surface 71Ra of the flat wire 71R. Alternatively, in the first step, the laser beam LB may be irradiated onto the tip surface 71Ra of the flat wire 71R, and in the second step, the laser beam LB may be irradiated onto the tip surface 71La of the flat wire 71L. That is, the first tip surface of the first flat wire may be the tip surface 71Ra of the flat wire 71R, and the second tip surface of the second flat wire may be the tip surface 71La of the flat wire 71L.

[0036] In this case, in the third step, the irradiation start position of the laser beam LB is set to a position on the surface of the first molten portion 72L that is shifted outward from the center of the tip surface 71La on the opposite side from the tip surface 71Ra, and the laser beam LB is moved from the irradiation start position toward the second molten portion 72R. The irradiation end position of the laser beam LB may be set to a position on the first molten portion 72L, or to a position on the surface of the first molten portion 72L that is on the tip surface 71Ra side of the end of the tip surface 71La on the tip surface 71Ra side. The irradiation end position may be set to a position on the surface of the second molten portion 72R, or to a position corresponding to the center of the tip surface 71Ra.

[0037] In the first step shown in Figures 3 and 4, and the second step shown in Figures 5 and 6, the beam spot Bs is positioned at a fixed point which is the center of the tip surfaces 71La and 71Ra of the rectangular wires 71L and 71R, as shown in Figure 13(a). As shown in Figure 13(b), the NC device 10 may control the galvanometer scanner 42 so that the beam spot Bs traces a circle. As shown in Figure 13(c), the NC device 10 may control the galvanometer scanner 42 so that the beam spot Bs traces an ellipse.

[0038] As shown in Figure 13(d), the NC device 10 may control the galvanoscanner 42 so that the beam spot Bs traces a straight line. Here, the direction of the straight line is perpendicular to the direction of movement of the laser beam LB in the third step. As shown in Figure 13(e), the NC device 10 may control the galvanoscanner 42 so that the beam spot Bs traces the number 8 (or the symbol for infinity). As shown in Figure 13(f), the NC device 10 may control the galvanoscanner 42 so that the beam spot Bs traces a spiral.

[0039] The vibration of the laser beam LB irradiating the tip surfaces 71La and 71Ra, as shown in Figures 13(b) to (f), is called wobbling. The NC device 10 may control the galvanoscanner 42 in the first step to cause the laser beam LB irradiating the tip surface 71La to wobble in a predetermined pattern. The NC device 10 may control the galvanoscanner 42 in the second step to cause the laser beam LB irradiating the tip surface 71Ra to wobble in a predetermined pattern. The NC device 10 may control the galvanoscanner 42 in both the first and second steps to cause the laser beam LB irradiating the tip surfaces 71La and 71Ra to wobble in a predetermined pattern.

[0040] As shown in Figures 13(b) to (f), wobbling the laser beam LB allows for wider melting of the tip surface 71La and 71Ra while suppressing sputter generation, compared to irradiating a fixed point within the tip surface 71La and 71Ra with the laser beam LB shown in Figure 13(a).

[0041] In the third step shown in Figures 7 and 8 above, the laser beam LB irradiating the first molten section 72L and the second molten section 72R is moved in a straight line, as shown in Figure 14(a). As shown in Figure 14(b), the NC device 10 may control the galvanometer scanner 42 so that the laser beam LB moves while the beam spot Bs traces a circle similar to that in Figure 13(b). The NC device 10 may also control the galvanometer scanner 42 so that the laser beam LB moves while the beam spot Bs traces an ellipse similar to that in Figure 13(c).

[0042] As shown in Figure 14(c), the NC device 10 may control the galvanoscanner 42 so that the laser beam LB moves while the beam spot Bs traces a straight line similar to that in Figure 13(d). As shown in Figure 14(d), the NC device 10 may control the galvanoscanner 42 so that the laser beam LB moves while the beam spot Bs traces the number 8 similar to that in Figure 13(e). In any of the patterns shown in Figures 14(b) to (d), the galvanoscanner 42 displaces the laser beam LB to trace a circle, a straight line, or the number 8 while moving the laser beam LB, so the actual pattern is the pattern shown in Figures 13(b), (d), and (e) plus the displacement in the direction of movement of the laser beam LB. When the laser beam LB is wobbled in the third step, the first molten section 72L and the second molten section 72R can be melted over a wide area while suppressing the generation of sputter.

[0043] As shown in Figure 15, in the fourth step shown in Figures 11 and 12, the NC device 10 may control the galvanoscanner 42 so that the beam spot Bs traces an ellipse approximately in the center of the bridge 73. Here, the ellipse is one in which the major axis is in the direction in which the flat wires 71L and 71R are aligned. In the fourth step, the NC device 10 may control the galvanoscanner 42 so that the beam spot Bs traces a circle approximately in the center of the bridge 73, or it may control the galvanoscanner 42 so that the beam spot Bs traces a straight line in the direction in which the flat wires 71L and 71R are aligned. The NC device 10 may control the galvanoscanner 42 so that the beam spot Bs traces the number 8 approximately in the center of the bridge 73, or it may control the galvanoscanner 42 so that it traces a spiral.

[0044] In the fourth step, by wobbling the laser beam LB in a predetermined pattern, the bridge 73 can be melted over a wide area while suppressing sputter generation, compared to when the laser beam LB is irradiated to a fixed point within the bridge 73.

[0045] In the multiple pairs of flat wires 71L and 71R, each pair of flat wires 71L and 71R is positioned sequentially directly below the processing head 40, and the laser welding machine 100 sequentially welds each pair of flat wires 71L and 71R using the laser welding method described above.

[0046] Using the photographs shown in Figures 16 to 20, which serve as substitutes for drawings, we will now explain how the flat wires 71L and 71R are actually welded by the laser welding method according to one or more embodiments described above. Figures 16 to 20 are photographs of the flat wires 71L and 71R taken from an oblique angle above, either before or after welding. Figure 16 shows the flat wires 71L and 71R before welding. Figure 17 shows the first step. As shown in Figure 17(a), the laser welding machine 100 starts irradiating the center of the tip surface 71La of the flat wire 71L with the laser beam LB. Then, as shown in Figure 17(b), the tip of the flat wire 71L melts, and a nearly spherical molten metal portion 72Lm is formed. Metal vapor Vp is ejected upward from the molten metal portion 72Lm.

[0047] As shown in Figure 17(c), after irradiation of the tip surface 71La with the laser beam LB is complete, a first molten portion 72L is formed on the rectangular wire 71L. The first molten portion 72L shown in Figure 17(c) is in a state where the molten metal portion 72Lm has begun to solidify.

[0048] Figure 18 shows the second step. As shown in Figure 18(a), the laser welding machine 100 starts irradiating the center of the tip surface 71Ra of the rectangular wire 71R with the laser beam LB. Then, as shown in Figure 18(b), the tip of the rectangular wire 71R melts, and a nearly spherical molten metal portion 72Rm is formed. Metal vapor Vp is ejected upward from the molten metal portion 72Rm. The first molten portion 72L is solidifying. As shown in Figure 18(c), when the irradiation of the tip surface 71Ra with the laser beam LB is finished, a second molten portion 72R is formed on the rectangular wire 71R. The second molten portion 72R shown in Figure 18(c) is in a state where the molten metal portion 72Rm is beginning to solidify.

[0049] Figure 19 shows the third step. As shown in Figure 19(a), the laser welding machine 100 irradiates the surface of the second molten section 72R with a laser beam LB at a position corresponding to a position shifted outward from the center of the tip surface 71Ra. As a result, the second molten section 72R melts, and metal vapor Vp is ejected diagonally upward. As shown in Figure 19(b), as the laser beam LB moves toward the first molten section 72L, a portion of the molten metal from the second molten section 72R moves toward the first molten section 72L. As the laser beam LB moves toward the first molten section 72L, the first molten section 72L also melts.

[0050] As shown in Figure 19(c), the laser welding machine 100 moves the laser beam LB to a position corresponding to the center of the tip surface 71La on the surface of the first molten part 72L, for example. The synergistic effect of irradiating the laser beam LB to a position corresponding to a position shifted outward from the center of the tip surface 71Ra and moving the laser beam LB in the direction of the first molten part 72L ensures the formation of a bridge 73 connecting the first molten part 72L and the second molten part 72R. Figure 19(d) shows the state in which the bridge 73 has begun to solidify.

[0051] Figure 20 shows the fourth step. Figures 20(a) to (c) show an example of the laser beam LB illuminating the bridge 73 in a wobbling motion, as shown in Figure 15. Figure 20(d) shows the bridge 73 after irradiation with the laser beam LB is complete. Comparing the bridge 73 shown in Figure 19(d) with the bridge 73 shown in Figure 20(d), it can be seen that the amount of molten metal increases due to irradiation with the laser beam LB on the bridge 73, causing the bridge 73 to grow in height. Figure 20(e) shows the final bridge 74 after the bridge 73 has solidified.

[0052] As described above, according to the laser welding machine and laser welding method according to one or more embodiments, in the third step, a portion of the molten metal in the second molten part 72R can be moved to the first molten part 72L, so that even if there is a gap between the rectangular wires 71L and 71R, a bridge 74 that closes the gap can be formed. Therefore, the laser beam LB does not enter the gap between the rectangular wires 71L and 71R, and the coating of the coated copper wires 61L and 61R is not burned off. According to the laser welding machine and laser welding method according to one or more embodiments, the rectangular wires 71L and 71R can be welded well.

[0053] The present invention is not limited to the one or more embodiments described above, and can be modified in various ways without departing from the spirit of the invention. [Explanation of Symbols]

[0054] 10 NC device 20 Blue laser oscillator 30 transmission fibers 40 Machining Heads 41 Collimating Lens 42 Galvanometer Scanner 43 Focusing lens 50 Cameras 61L,61R coated copper wire 71L,71R flat wire 71La,71Ra Tip surface 72L First molten section 72R Second molten section 73,74 Bridge 100 laser welding machines LB laser beam Vp Metal vapor

Claims

1. A laser oscillator that emits a laser beam, A transmission fiber for transmitting the laser beam emitted from the laser oscillator, A processing head having a collimating lens that converts a divergent laser beam emitted from the exit end of the transmission fiber into collimated light, a focusing lens that focuses the collimated laser beam and irradiates a pair of adjacent flat wires to be welded, and a displacement mechanism that displaces the laser beam irradiating the pair of flat wires, A control device that controls the emission of the laser beam by the laser oscillator and the displacement of the laser beam by the displacement mechanism, Equipped with, The control device is The laser oscillator and the displacement mechanism are controlled to melt the tip of the first rectangular wire, which is one of the pair of rectangular wires, by irradiating the center of the first tip surface of the first rectangular wire with a first laser beam, thereby forming a first molten portion on the first rectangular wire. The laser oscillator and the displacement mechanism are controlled to melt the tip of the second rectangular wire, which is the other of the pair of rectangular wires, by irradiating the center of the second tip surface of the second rectangular wire with a second laser beam, thereby forming a second molten portion on the second rectangular wire. The laser oscillator and the displacement mechanism are controlled to move the third laser beam from the irradiation start position toward the first molten portion, with the third laser beam being moved toward the first molten portion, with the irradiation start position being defined as a position on the surface of the second molten portion that is shifted outward from the center of the second tip surface, opposite to the first tip surface. Laser welding machine.

2. The displacement mechanism is a galvanoscanner that displaces the laser beam of collimating light emitted from the collimating lens and causes it to be incident on the focusing lens. The galvanometer scanner comprises first and second galvanometer mirrors and first and second galvanometer motors that drive the first and second galvanometer mirrors, respectively. The control device controls the rotation of the first and second galvanometer mirrors by the first and second galvanometer motors. The laser welding machine according to claim 1.

3. The laser welding machine according to claim 1 or 2, wherein the control device controls the laser oscillator so that metal vapor is generated from the second molten portion by irradiating the surface of the second molten portion with the third laser beam.

4. The laser welding machine according to claim 1 or 2, wherein the control device controls the displacement mechanism so that a bridge connecting the first molten portion and the second molten portion is formed by moving a portion of the molten metal of the second molten portion, which has been melted by irradiation with the third laser beam, to the first molten portion.

5. The laser welding machine according to claim 4, wherein the control device controls the laser oscillator and the displacement mechanism to irradiate the surface of the bridge with a fourth laser beam to increase the amount of molten metal as the bridge or to shape the bridge.

6. The laser welding machine according to claim 1 or 2, wherein the control device controls the displacement mechanism to cause the first and second laser beams to wobble in a predetermined pattern.

7. The laser welding machine according to claim 1 or 2, wherein the control device controls the displacement mechanism to cause the third laser beam to wobble in a predetermined pattern.

8. The laser welding machine according to claim 5, wherein the control device controls the displacement mechanism to cause the fourth laser beam to wobble in a predetermined pattern.

9. A first step is to irradiate the center of the first tip surface of a first flat wire, which is one of a pair of flat wires to be welded adjacent to each other, with a first laser beam to melt the tip of the first flat wire and form a first molten portion on the first flat wire, A second step is to irradiate the center of the second tip surface of the second rectangular wire, which is the other of the pair of rectangular wires, with a second laser beam to melt the tip of the second rectangular wire and form a second molten portion on the second rectangular wire. A third step involves setting a position on the surface of the second molten portion that corresponds to a position on the surface of the second tip surface that is shifted outward from the center of the second tip surface, opposite to the first tip surface, as the irradiation start position for the third laser beam, and moving the third laser beam from the irradiation start position toward the first molten portion. A laser welding method including [specific type of laser welding].

10. The laser welding method according to claim 9, wherein in the third step, metal vapor is generated by irradiating the surface of the second molten portion with the third laser beam.

11. The laser welding method according to claim 10, wherein the third step is to move a portion of the molten metal of the second molten portion, which has been melted by irradiation with the third laser beam, to the first molten portion, thereby forming a bridge connecting the first molten portion and the second molten portion.

12. The laser welding method according to claim 11, further comprising a fourth step of irradiating the surface of the bridge with a fourth laser beam to increase the amount of molten metal as the bridge or to shape the bridge.

13. The laser welding method according to any one of claims 9 to 12, wherein the first and second steps each include a step of wobbling the first and second laser beams in a predetermined pattern.

14. The laser welding method according to any one of claims 9 to 12, wherein the third step is to wobble the third laser beam in a predetermined pattern.

15. The laser welding method according to claim 12, wherein the fourth step is to wobble the fourth laser beam in a predetermined pattern.

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