Laser welding method and manufacturing method for rotating electric machine

Abstract

A laser welding method according to an embodiment involves using a laser beam to alternately irradiate an end portion of a first linear member and an end portion of a second linear member adjacent to the first linear member. and weld the end portion of the first linear member and the end portion of the second linear member. The laser welding method comprises the steps of: radiating the laser beam along a loop-shaped first movement path at the end portion of the first linear member; stopping the radiation of the laser beam and moving the position irradiated by the laser beam along a linear second movement path from the end portion of the first linear member to the end portion of the second linear member; radiating the laser beam along a loop-shaped third movement path at the end portion of the second linear member; and stopping the radiation of the laser beam and moving the position irradiated by the laser beam along a linear fourth movement path from the end portion of the second linear member to the end portion of the first linear member. The second movement path contacts the first movement path and the third movement path, and the fourth movement path contacts the first movement path and the third movement path at a position where the fourth movement path faces the second movement path.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a laser welding method and a method for manufacturing a rotating electric machine. [Background technology]

[0002] For example, a technique has been proposed in which two linear members are arranged side by side and a laser beam is irradiated onto an end of one linear member and an end of the adjacent other linear member to weld the ends of the two linear members. In this case, if there is a gap between the ends of the two linear members, the laser beam may leak through the gap. If the laser beam leaks through the gap between the ends, for example, it may damage a coating provided on the side of the linear members or a member provided on the opposite side of the linear members from the end to be welded.

[0003] For this reason, a technique has been proposed in which the ends of linear members are brought into close contact with each other using a jig. However, since the ends of linear members vary in size, shape, and deformation, it is difficult to prevent gaps from forming between the ends of the linear members.

[0004] Therefore, a technique has been proposed in which the ends of the two linear members are individually irradiated with laser light. In this way, the laser light can be prevented from irradiating the gap between the ends of the linear members. However, this makes the configuration and control program of the laser welding device complex.

[0005] Furthermore, a technique has been proposed in which the laser beam irradiation is stopped when the irradiation position of the laser beam moves from the end of one linear member to the end of the other linear member. This prevents the laser beam from irradiating the gap between the ends of the linear members. However, the ends of the linear members vary in size, shape, and deformation. The gap size also varies. In this case, the gap size can be measured in advance, and the timing and duration for stopping the laser beam irradiation can be set each time. However, this requires a process and a measuring device for measuring the gap size. Therefore, there has been a demand for the development of a technology that can prevent laser light from being irradiated into the gap between the ends of linear members in a simple manner. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-20340 [Patent Document 2] International Publication No. 2019 / 159737 Summary of the Invention [Problem to be solved by the invention]

[0007] The problem that the present invention aims to solve is to provide a laser welding method and a method for manufacturing a rotating electric machine that can simply prevent laser light from being irradiated into the gap between the ends of linear members. [Means for solving the problem]

[0008] The laser welding method of the embodiment is a laser welding method in which laser light is alternately irradiated onto an end of a first linear member and an end of a second linear member adjacent to the first linear member, thereby welding the end of the first linear member and the end of the second linear member. The laser welding method includes a first step of irradiating an end of the first linear member with the laser beam along a first movement path that is looped, a second step of stopping the irradiation of the laser beam and moving the irradiation position of the laser beam from the end of the first linear member to the end of the second linear member along a second movement path that is linear, a third step of irradiating the end of the second linear member with the laser beam along a third movement path that is looped, and a fourth step of stopping the irradiation of the laser beam and moving the irradiation position of the laser beam from the end of the second linear member to the end of the first linear member along a fourth movement path that is linear, wherein the second movement path is tangent to the first movement path and the third movement path, and the fourth movement path is tangent to the first movement path and the third movement path at a position opposite to the second movement path. In the first irradiation of the laser light, when the irradiation position of the laser light is moved from the start position of irradiation of the laser light at the end of the first linear member in a direction away from the end of the second linear member, the irradiation position of the laser light is moved 1.5 times along the first movement path from the start position of irradiation of the laser light, and at the end of the second linear member, the irradiation position of the laser light is moved 1.5 times along the third movement path in the same direction as the movement direction on the first movement path. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic perspective view illustrating a stator. [Figure 2] FIG. 2 is a schematic diagram illustrating the segments before they are attached to the core. [Figure 3] FIG. 2 is a schematic diagram illustrating a coil attached to a core. [Figure 4] 10A and 10B are schematic views illustrating laser welding of a conductor portion according to a comparative example. [Figure 5] 10A and 10B are schematic views illustrating laser welding of conductor portions according to another comparative example. [Figure 6] 5A to 5C are schematic views illustrating laser welding of the conductor portion according to the present embodiment. [Figure 7] 10A and 10B are schematic diagrams illustrating the movement path of the irradiation position. [Figure 8] 10A and 10B are schematic views illustrating a movement path of an irradiation position according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The laser welding method according to this embodiment can be used to weld together the ends of linear members arranged side by side. For example, rotating electrical machines such as motors and generators have a coil wound around a core. In recent years, after inserting multiple segments into slots, a laser beam is irradiated onto the end of one segment and the end of an adjacent segment to form a coil wound around the core. Therefore, the following describes a method for manufacturing a stator as an example, and also describes the laser welding method according to this embodiment. In other words, the present invention can be applied to a method for manufacturing a rotating electrical machine. Furthermore, to illustrate a method for manufacturing a stator, a linear member having a rectangular cross-sectional shape (for example, the conductor portion 31a of the segment 31 described later) is used as an example, but the present invention can also be applied to, for example, a linear member having a polygonal cross-sectional shape.

[0011] In addition, in this specification, the movement path of the laser beam irradiation position is the movement path along which the center of the laser spot moves when the laser beam is irradiated, and is the movement path along which the center of the laser spot moves when the laser beam irradiation is stopped, assuming that the laser spot is formed. For example, the movement path of the laser beam irradiation position can be determined in advance depending on the cross-sectional shape and cross-sectional dimensions of the linear member (e.g., the conductor portion 31a of the segment 31 described later). Data on the predetermined movement path is stored, for example, in a controller of the laser welding device, and is used when performing the laser welding method described later.

[0012] Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate. First, the stator 1 will be illustrated. FIG. 1 is a schematic perspective view illustrating a stator 1. As shown in FIG. As shown in FIG. 1, a stator 1 is provided with a core 2 and a coil 3.

[0013] The core 2 may be formed by laminating multiple annular magnetic members in the axial direction of the stator 1 (Z direction in FIG. 1 ). The magnetic members may be formed, for example, from electromagnetic steel sheets (silicon steel sheets). The core 2 has a yoke 21 and multiple teeth 22. The yoke 21 is cylindrical and located on the outer periphery of the core 2. The multiple teeth 22 are provided at equal intervals on the inner circumferential surface of the yoke 21. Each of the multiple teeth 22 protrudes from the inner circumferential surface of the yoke 21 toward the center of the core 2 and extends in the axial direction of the stator 1. Grooves provided between the teeth 22 serve as slots 23. The shape, number, and size of the teeth 22 are not limited to those illustrated and may be changed as appropriate depending on the application, size, specifications, etc. of the rotating electric machine in which the stator 1 is installed.

[0014] The coil 3 includes a plurality of segments 31 . FIG. 2 is a schematic diagram illustrating the segment 31 before it is attached to the core 2. As shown in FIG. As shown in FIG. 2, the segment 31 has a conductor portion 31a and an insulating film 31b. The conductor portion 31a may have a substantially U-shaped appearance before being attached to the core 2. The conductor portion 31a is made of a material with high conductivity. The conductor portion 31a may be made of, for example, so-called pure copper or a material containing copper as a main component. The conductor portion 31a may also be made of a rectangular wire. The rectangular wire is a linear member with a rectangular cross section. The cross-sectional dimension of the rectangular wire may be, for example, approximately 1 mm to 4 mm.

[0015] The insulating film 31b covers the outer surface of the conductor portion 31a. However, the insulating film 31b is not provided near both ends of the conductor portion 31a, so that the conductor portion 31a is exposed. The insulating film 31b includes, for example, enamel.

[0016] FIG. 3 is a schematic diagram illustrating the coil 3 attached to the core 2. As shown in FIG. 3, the segment 31 is provided inside the slot 23. Both ends of the segment 31 protrude from one end of the core 2. The portion of the segment 31 protruding from one end of the core 2 extends in a direction approaching the adjacent segment 31.

[0017] Furthermore, the vicinity of the portion of the conductor portion 31a exposed from the insulating film 31b extends in the axial direction (Z direction in FIG. 3) of the core 2. In the circumferential direction of the core 2 (direction around the central axis of the core 2), the portion of the conductor portion 31a exposed from the insulating film 31b overlaps with the portion of the adjacent conductor portion 31a exposed from the insulating film 31b.

[0018] The ends of adjacent conductor portions 31a are laser welded to each other. A single coil 3 is formed by connecting a plurality of segments 31 via welds 31c.

[0019] In this case, multiple coils 3 can be arranged side by side in the radial direction of the core 2 (a direction passing through the central axis of the core 2 and perpendicular to the Z direction). For example, as illustrated in FIG. 1, three coils 3 for U, V, and W phases can be provided. Note that the external shape, number, size, etc. of the coils 3 and segments 31 are not limited to those illustrated, and can be changed as appropriate depending on the application, size, specifications, etc. of the rotating electrical machine in which the stator 1 is installed. For example, four coils 3 can be arranged side by side in the radial direction of the core 2.

[0020] Next, a method for manufacturing the stator 1 will be illustrated. First, the core 2 is formed. For example, a plurality of plate-shaped magnetic members each having portions that will become the yoke 21 and the plurality of teeth 22 are formed. For example, the magnetic members are formed by punching electromagnetic steel plates with a thickness of approximately 0.05 mm to 1.0 mm. Then, the plurality of magnetic members are stacked and, for example, welded or crimped to form the core 2. The core 2 can also be formed by pressure-molding magnetic material powder and a resin binder.

[0021] Next, a plurality of segments 31 that will become components of the coil 3 are formed. First, a paint containing enamel or the like is applied to the outer surface of a rectangular wire having a predetermined length to form the insulating film 31b. Alternatively, the surface of the rectangular wire may be coated with a paint containing enamel or the like and then cut to a predetermined length. Alternatively, a rectangular wire coated with enamel or the like may be purchased and cut to a predetermined length.

[0022] Next, as shown in FIG. 2, the insulating film 31b near both ends of the conductor portion 31a is peeled off to expose the conductor portion 31a. Subsequently, the conductor portion 31a is formed by bending it into a substantially U-shape. In this manner, a plurality of segments 31 can be formed.

[0023] Next, as shown in FIG. 3, each of the multiple segments 31 is mounted in a predetermined slot 23 of the core 2. For example, each of the multiple segments 31 is inserted into a predetermined slot 23 from the axial direction of the core 2 (Z direction in FIG. 1). At this time, one segment 31 is inserted across multiple slots 23. The coil 3 according to this embodiment can be a so-called distributed winding coil. The coil 3 according to this embodiment can also be a so-called wave winding coil.

[0024] 3, the portion of each segment 31 protruding from the core 2 is bent toward the adjacent segment 31. Then, the portion of each conductor 31a near the portion exposed from the insulating film 31b is bent in the axial direction of the core 2 (the Z direction in FIG. 3). In the circumferential direction of the core 2, the portion of each conductor 31a exposed from the insulating film 31b is made to overlap the portion of the adjacent conductor 31a exposed from the insulating film 31b. By repeating the above procedure, a plurality of sets of the segments 31 arranged in the circumferential direction of the core 2 are provided in the radial direction of the core 2.

[0025] Although the above example illustrates a case where multiple segments 31 are bent after being fitted into slots 23, the present invention is not limited to this. For example, multiple segments 31 may be bent, and each of the multiple bent segments 31 may be fitted into a predetermined slot 23. In this case, the bent segments 31 may be fitted from the inside to the outside of the core 2.

[0026] Furthermore, a cylindrical insulating cover can be provided inside the core 2 to which the plurality of segments 31 are attached to close the opening of the slot 23 .

[0027] Next, the ends of adjacent segments 31 (conductor portions 31a) are welded together to form a plurality of coils 3 fitted in the slots . When welding, a jig can be used to move the ends of adjacent conductor portions 31a closer to each other. For example, a jig can be used that has an annular member provided inside the multiple segments 31 arranged circumferentially around the core 2 and an annular member provided outside the multiple segments 31. When the annular member provided inside the multiple segments 31 is attached, one end of each of the multiple conductor portions 31a is pressed toward the outside of the core 2. When the annular member provided outside the multiple segments 31 is attached, the other end of each of the multiple conductor portions 31a is pressed toward the inside of the core 2. Therefore, the jig moves the ends of adjacent conductor portions 31a in directions that move closer to each other. The multiple conductor portions 31a are also held by the jig.

[0028] The configuration of the jig is not limited to the example shown. Any jig may be used as long as it brings the ends of adjacent conductor portions 31a closer to each other. Welding can also be performed without using a jig. However, using a jig can improve the quality of the welded portion 31c and the workability of the welding work.

[0029] The ends of adjacent conductor portions 31a can be welded together by irradiating the ends of the conductor portions 31a with laser light. That is, the ends of adjacent conductor portions 31a can be laser welded together.

[0030] Laser welding can be performed using a laser beam with a wavelength in the infrared region. This makes it easier to irradiate a laser beam with a relatively high output. For example, the output of the laser beam can be about 4 kW.

[0031] The laser welding device used to weld the end of the conductor portion 31a may be, for example, a fiber laser welding device or a disk laser welding device. The laser welding device is preferably a CW laser (Continuous Wave Laser) welding device that can continuously emit laser light. Furthermore, the laser welding device is capable of moving the irradiation position of the laser light. For example, the laser welding device may be equipped with a galvanometer mirror or the like.

[0032] Here, if the end of the conductor portion 31a is laser-welded in the atmosphere, the welded portion 31c may be oxidized or blowholes may occur, resulting in a deterioration in the quality of the welded portion 31c. Therefore, it is preferable to perform the laser welding of the end of the conductor portion 31a in an atmosphere of an inert gas such as nitrogen gas or argon, or to supply an inert gas near the end of the conductor portion 31a to be laser-welded. In this way, the quality of the welded portion 31c can be improved.

[0033] The ends of adjacent conductor portions 31a are welded together to form the welded portion 31c illustrated in Figures 1 and 3. A single coil 3 is formed by connecting multiple segments 31 (conductor portions 31a) in series. A plurality of coils 3 are also formed, arranged in the radial direction of the core 2. For example, three coils 3 for the U phase, V phase, and W phase can be formed by shifting the slots 23 one by one. The details of welding the ends of the segments 31 (conductor portions 31a) will be described later.

[0034] Next, resin or the like is applied to the exposed portion of the coil 3 where the conductor portion 31a is exposed to insulate it. Next, the plurality of coils 3 are fixed to the core 2. For example, the coils 3 are fixed to the core 2 by dropping varnish into the gaps between the slots 23 and the coils 3 and then hardening the varnish. In this manner, the stator 1 can be manufactured.

[0035] Next, welding of the ends of the segments 31 (conductor portions 31a) will be further described. As described above, the ends of adjacent conductor portions 31a are welded by irradiating the ends of the conductor portions 31a with laser light. In this case, if there is a gap between the ends of adjacent conductor portions 31a, the laser light may pass through the gap and be irradiated onto the side of the segment 31 opposite to the end to be welded. As shown in FIGS. 2 and 3, an insulating film 31b is provided on the outer surface of the conductor portion 31a. Therefore, if laser light is irradiated onto the side of the segment 31 opposite to the end to be welded through the gap, the insulating film 31b may be damaged by the laser light. Furthermore, for example, a member or the like provided on the side of the segment 31 opposite to the end to be welded may be damaged by the laser light.

[0036] In this case, the use of the aforementioned jig can reduce the gap between the ends of adjacent conductors 31a. However, the ends of the conductors 31a have variations in size, shape, and deformation. Therefore, even if the jig is used, it is difficult to eliminate the gap between the ends of adjacent conductors 31a.

[0037] FIG. 4 is a schematic view illustrating laser welding of the conductor portion 31a according to the comparative example. 4 shows a case where laser light is irradiated individually onto the ends of adjacent conductors 31a. For example, as shown in FIG. 4, one end of one conductor 31a is irradiated with laser light, and the other end of the other conductor 31a is irradiated with another laser light. The laser light irradiation is performed simultaneously.

[0038] At the end of one conductor portion 31a, the movement path 101 of the laser beam irradiation position is made to form a loop. The looped laser beam irradiation is performed multiple times in succession. The movement path 101 of the laser beam irradiation position is made to gradually become larger. The end of one conductor portion 31a is heated by the laser beam irradiation, and a molten pool is formed.

[0039] At the end of the other conductor portion 31a, the movement path 102 of the laser beam irradiation position is made to form a loop. The looped laser beam irradiation is performed multiple times in succession. The movement path 102 of the laser beam irradiation position is made to gradually become larger. The end of the other conductor portion 31a is heated by the laser beam irradiation, and a molten pool is formed.

[0040] As the movement paths 101 and 102 of the loop-shaped laser beam irradiation position become larger, the molten pools formed between the ends of the conductors 31a fuse together, thereby connecting the ends of one conductor 31a to the other conductor 31a via a weld.

[0041] If the laser beam is irradiated individually onto the ends of adjacent conductors 31a, the laser beam is not irradiated onto the gaps 31a1 between the ends of the conductors 31a, which prevents the insulating film 31b of the segment 31 from being damaged by the laser beam.

[0042] However, this requires two laser welding devices, two optical systems for irradiating the laser light, and the control program for the laser welding devices becomes complicated.

[0043] FIG. 5 is a schematic view illustrating laser welding of a conductor portion 31a according to another comparative example. As shown in FIG. 5, the movement path 103 of the laser beam irradiation position is looped relative to the two ends of adjacent conductors 31a. In this case, when the laser beam irradiation position moves from the outer edge of one end of the conductor 31a to the outer edge of the other end of the conductor 31a, the laser beam irradiation is stopped. Furthermore, when the laser beam irradiation position moves to the outer edge of the other end of the conductor 31a, the laser beam irradiation is resumed. The looped movement path 103 of the laser beam irradiation position set relative to the ends of the two conductors 31a is gradually narrowed. By the laser beam irradiation, molten pools formed at the ends of the adjacent conductors 31a fuse together between the ends of the conductors 31a. Therefore, the end of one conductor 31a and the end of the other conductor 31a are connected via a weld.

[0044] If the irradiation of the laser light is stopped when the irradiation position of the laser light moves from the outer edge of one end of the conductor portion 31a to the outer edge of the other end of the conductor portion 31a, the laser light is not irradiated into the gap 31a1 between the ends of the conductor portions 31a, and therefore, damage to the insulating film 31b of the segment 31 by the laser light can be prevented.

[0045] However, the end of the conductor portion 31a has variations in size, shape, and deformation. The gap 31a1 also has variations in size. Therefore, when laser light irradiation is started and stopped at the outer edge of the end of the conductor portion 31a, stopping and restarting the laser light irradiation at a predetermined timing may result in the laser light being irradiated into the gap 31a1. In this case, the laser light can be prevented from irradiating the gap 31a1 by extending the time for stopping the laser light irradiation. However, doing so shortens the laser light irradiation time, making it difficult to heat the end of the conductor portion 31a. Alternatively, the size of the gap 31a1 can be measured in advance and the timing for stopping the laser light irradiation and the stop time (the timing for restarting the laser light irradiation) can be set on an individual basis. However, doing so requires a process and a measuring device for measuring the size of the gap 31a1.

[0046] FIG. 6 is a schematic view illustrating laser welding of the conductor portion 31a according to the present embodiment. In the laser welding of the conductor portion 31a in this embodiment, laser light is alternately irradiated to the end of one conductor portion 31a (corresponding to an example of a first linear member) and the end of the other adjacent conductor portion 31a (corresponding to an example of a second linear member), thereby welding the ends of the adjacent conductor portions 31a together.

[0047] For example, as shown in FIG. 6, the end of one conductor portion 31a is irradiated with laser light along a movement path 100 (corresponding to an example of a first movement path) of the laser light irradiation position that has a loop shape. Next, the irradiation of the laser light is stopped, and the irradiation position of the laser light is moved from the end of one conductor portion 31a to the end of the other conductor portion 31a along the linear movement path 100b (corresponding to an example of the second movement path) of the irradiation position of the laser light. Next, the irradiation of the laser light is resumed at the end of the other conductor portion 31a, and the laser light is irradiated along a movement path 100 (corresponding to an example of a third movement path) of the laser light irradiation position which has a loop shape. Next, the irradiation of the laser light is stopped, and the irradiation position of the laser light is moved from the end of the other conductor portion 31a to the end of one of the conductor portions 31a along the linear movement path 100b (corresponding to an example of the fourth movement path) of the irradiation position of the laser light. Thereafter, the above-described procedure is repeated multiple times to alternately irradiate the laser beam onto the ends of adjacent conductor portions 31a, thereby forming molten pools.

[0048] In this case, the loop-shaped movement path 100 of the irradiation position at each end of the adjacent conductor portions 31a can have, for example, the same shape and the same size. Since the cross-sectional shapes and cross-sectional dimensions of adjacent linear members (conductor portions 31a) are the same, the shape and size of the movement path 100 of the loop-shaped irradiation position are made the same. However, for example, if at least one of the cross-sectional shapes and cross-sectional dimensions of adjacent linear members is different, at least one of the shape and size of the movement path 100 of the loop-shaped irradiation position may be different.

[0049] In the following, a case will be described in which the loop-shaped movement path 100 of the irradiation position has the same shape and size at each end of adjacent linear members (conductor portions 31a).

[0050] There are no particular limitations on the shape of the loop-shaped path 100 of movement of the irradiation position. However, it is preferable that the shape of the loop-shaped path 100 of movement of the irradiation position be a shape made up of curves such as a circle or ellipse, or a shape made up of curves and straight lines as shown in Fig. 6. If the shape of the loop-shaped path 100 of movement of the irradiation position is made like this, the operation of the galvanometer mirror and the like will be smoother.

[0051] There is no particular limitation on the size of the movement path 100 of the loop-shaped irradiation position. However, as illustrated in Fig. 6, it is preferable that the shortest distance L between the outer edge of the laser spot 100a and the outer edge of the end of one conductor 31a is constant at the end of one conductor 31a. It is also preferable that the shortest distance L between the outer edge of the laser spot 100a and the outer edge of the end of the other conductor 31a is constant at the end of the other conductor 31a.

[0052] Laser light is irradiated along the loop-shaped movement path 100 of the irradiation position, and the ends of adjacent conductors 31a are heated. The molten pools formed at the ends of adjacent conductors 31a fuse together between the ends of the conductors 31a. As a result, the ends of one conductor 31a and the other conductor 31a are connected via a welded portion 31c.

[0053] Furthermore, when moving from the loop-shaped movement path 100 of the irradiation position at the end of one conductor portion 31a to the loop-shaped movement path 100 of the irradiation position at the end of the other conductor portion 31a, the irradiation of the laser light is stopped. For example, as shown in FIG. 6, a pair of linear movement paths 100b of the irradiation position can be provided in the direction in which the ends of adjacent conductor portions 31a are aligned, connecting the loop-shaped movement path 100 of the irradiation position at the end of one conductor portion 31a with the loop-shaped movement path 100 of the irradiation position at the end of the other conductor portion 31a. The movement path 100b can be a straight line (common circumtangent) tangent to the two loop-shaped movement paths 100. The irradiation of the laser light is stopped at the movement path 100b of the irradiation position.

[0054] In this way, the laser beam is not irradiated between the loop-shaped movement path 100 of the irradiation position at the end of one conductor portion 31a and the loop-shaped movement path 100 of the irradiation position at the end of the other conductor portion 31a. In other words, the laser beam is not irradiated into the gap 31a1 between the ends of the conductor portions 31a. This prevents the insulating film 31b of the segment 31 from being damaged by the laser beam.

[0055] Furthermore, the end of the conductor portion 31a is heated along the movement path 100. Therefore, even if the laser light irradiation is stopped and then resumed at a position away from the outer edge of the end of the conductor portion 31a in the direction in which the ends of adjacent conductor portions 31a are aligned, heating of the end of the conductor portion 31a is not suppressed. For example, in the direction in which the ends of adjacent conductor portions 31a are aligned, the position at which the laser light irradiation is stopped can be set to approximately the center of the end of one conductor portion 31a, and the position at which the laser light irradiation is resumed can be set to approximately the center of the end of the other conductor portion 31a. Therefore, even if the ends of the conductor portions 31a have dimensional variations, shape variations, or deformations, or even if the dimensions of the gap 31a1 vary, irradiation of the laser light into the gap 31a1 can be effectively suppressed.

[0056] Furthermore, as shown in Figure 6, if the shortest distance L between the outer edge of the laser spot 100a and the outer edge of the end of the conductor portion 31a is constant, irradiation of the laser light into the gap 31a1 can be more effectively suppressed.

[0057] Furthermore, if the loop-shaped movement path 100 of the irradiation position has the same shape and size at each end of the adjacent conductor parts 31a, the control program for the irradiation of the laser light can be simplified.

[0058] Furthermore, if the movement path 100b of the irradiation position is a straight line (common external tangent) tangent to the two loop-shaped movement paths 100 of the irradiation position, linear movement is possible from one movement path 100 of the irradiation position to the other movement path 100 of the irradiation position. Therefore, it is possible to shorten the movement time from one movement path 100 of the irradiation position to the other movement path 100 of the irradiation position, and ultimately to shorten the takt time.

[0059] Next, the movement paths 100, 100b of the irradiation position according to this embodiment will be further described. 7(a) and (b) are schematic diagrams illustrating the movement paths 100 and 100b of the irradiation position. A laser beam is irradiated toward the end of one of the conductor parts 31a, and the center of the laser spot 100a is moved along a loop-shaped movement path 100 of the irradiation position.

[0060] As shown in FIG. 7(a), in the initial laser light irradiation, when the laser light irradiation position (center of the laser spot 100a) is moved from the laser light irradiation start position 200a at the end of one conductor portion 31a in a direction approaching the end of the other conductor portion 31a (in the example shown in FIG. 7(a), when the center of the laser spot 100a is moved counterclockwise), the center of the laser spot 100a is moved one revolution from the laser light irradiation start position 200a along the loop-shaped movement path 100 of the irradiation position. In other words, the laser light irradiation position is moved one revolution from the laser light irradiation start position 200a along the loop-shaped movement path 100 of the irradiation position. In this way, the movement of the center of the laser spot 100a along the loop-shaped movement path 100 of the irradiation position can be smoothly transitioned to movement along the linear movement path 100b of the irradiation position.

[0061] Next, the irradiation of the laser light is stopped, and the center of the laser spot 100a, assuming that the laser spot 100a has been formed, is moved along the linear irradiation position movement path 100b to the laser light irradiation start position 201a at the end of the other conductor portion 31a.

[0062] Next, as shown in FIG. 7(b), when the laser beam irradiation position reaches the laser beam irradiation start position 201a, the laser beam irradiation is resumed and the center of the laser spot 100a is moved from the laser beam irradiation start position 201a in a direction away from one of the conductors 31a. In the example shown in FIG. 7(b), the center of the laser spot 100a is moved counterclockwise. That is, the direction of movement of the laser spot 100a is made the same at each end of the adjacent conductors 31a. In this way, the movement of the center of the laser spot 100a becomes smooth.

[0063] Furthermore, the center of the laser spot 100a is moved 1.5 times from the laser light irradiation start position 201a along the loop-shaped movement path 100 of the irradiation position. That is, at the end of the other conductor 31a, the laser light irradiation position is moved 1.5 times along the movement path 100 of the irradiation position in the same direction as the movement direction of the irradiation position at the end of one conductor 31a. In this way, the movement of the center of the laser spot 100a along the loop-shaped movement path 100 of the irradiation position can be smoothly transitioned to movement along the linear movement path 100b of the irradiation position.

[0064] Next, the irradiation of the laser light is stopped, and the center of the laser spot 100a, assuming that the laser spot 100a has been formed, is moved along the linear irradiation position movement path 100b to the laser light irradiation start position 200b at the end of one of the conductor parts 31a.

[0065] Next, the laser beam irradiation is resumed at the laser beam irradiation start position 200b, and the center of the laser spot 100a is moved from the laser beam irradiation start position 200b in a direction away from the other conductor portion 31a, thereby making it possible to smoothly move the center of the laser spot 100a.

[0066] Furthermore, the center of the laser spot 100a is moved 1.5 times from the laser light irradiation start position 200b along the looped path of movement 100 of the irradiation position. In this way, the movement of the center of the laser spot 100a along the looped path of movement 100 of the irradiation position can be smoothly transitioned to the movement along the linear path of movement 100b of the irradiation position.

[0067] Thereafter, in the same manner, the center of the laser spot 100a is moved 1.5 times along the loop-shaped movement path 100 of the irradiation position at each of the ends of the adjacent conductors 31a.

[0068] 8(a) and 8(b) are schematic views illustrating movement paths 100 and 100b of the irradiation position according to another embodiment. In this embodiment as well, as shown in FIG. 8(a), a laser beam is irradiated toward the end of one conductor portion 31a, and the center of a laser spot 100a is moved along a loop-shaped movement path 100 of the irradiation position.

[0069] However, in this embodiment, in the initial laser light irradiation, the laser light irradiation position (center of laser spot 100a) is moved from laser light irradiation start position 200a at the end of one conductor portion 31a in a direction away from the end of the other conductor portion 31a. In the example shown in FIG. 8(a), the center of laser spot 100a is moved clockwise. In other words, the direction of movement of the center of laser spot 100a is opposite to that in the example shown in FIG. 7(a).

[0070] In this case, the center of the laser spot 100a is moved 1.5 times from the laser light irradiation start position 200a along the loop-shaped movement path 100 of the irradiation position. That is, the laser light irradiation position is moved 1.5 times from the laser light irradiation start position 200a along the movement path 100 of the irradiation position. In this way, the movement of the center of the laser spot 100a along the loop-shaped movement path 100 of the irradiation position can be smoothly transitioned to movement along the linear movement path 100b of the irradiation position.

[0071] Next, the irradiation of the laser light is stopped, and the center of the laser spot 100a, assuming that the laser spot 100a has been formed, is moved along the linear irradiation position movement path 100b to the laser light irradiation start position 201b at the end of the other conductor portion 31a.

[0072] Next, as shown in FIG. 8(b), when the laser beam irradiation position reaches the laser beam irradiation start position 201b, the laser beam irradiation is resumed and the center of the laser spot 100a is moved from the laser beam irradiation start position 201b in a direction away from one of the conductors 31a. In the example shown in FIG. 8(b), the center of the laser spot 100a is moved clockwise. That is, the direction of movement of the laser spot 100a is made the same at each end of the adjacent conductors 31a. In this way, the movement of the center of the laser spot 100a becomes smooth.

[0073] Furthermore, the center of the laser spot 100a is moved 1.5 times from the laser light irradiation start position 201b along the looped path of movement 100 of the irradiation position. In this way, the movement of the center of the laser spot 100a along the looped path of movement 100 of the irradiation position can be smoothly transitioned to the movement along the linear path of movement 100b of the irradiation position. That is, in this embodiment, at the end of the other conductor portion 31a, the irradiation position of the laser light is moved 1.5 times along the movement path 100 of the irradiation position in the same direction as the movement direction of the end of one conductor portion 31a on the movement path 100.

[0074] Next, the irradiation of the laser light is stopped, and the center of the laser spot 100a, assuming that the laser spot 100a has been formed, is moved along the linear irradiation position movement path 100b to the laser light irradiation start position 200a at the end of one of the conductor parts 31a.

[0075] Next, the laser beam irradiation is resumed at the laser beam irradiation start position 200a, and the center of the laser spot 100a is moved from the laser beam irradiation start position 200a in a direction away from the other conductor portion 31a, thereby making it possible to smoothly move the center of the laser spot 100a.

[0076] Furthermore, the center of the laser spot 100a is moved 1.5 times from the laser light irradiation start position 200a along the looped irradiation position movement path 100. In this way, the movement of the center of the laser spot 100a along the looped irradiation position movement path 100 can be smoothly transitioned to movement along the linear irradiation position movement path 100b.

[0077] Thereafter, in the same manner, the center of the laser spot 100a is moved 1.5 times along the loop-shaped movement path 100 of the irradiation position at each of the ends of the adjacent conductors 31a.

[0078] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0079] 1 stator 2 cores 3 coils 31 segments 31a Conductor 31a1 Gap 31b insulating film 100 Travel Path 100a laser spot 100b Travel Route 200a Irradiation start position 201a Irradiation start position 200b Irradiation start position 201b Irradiation start position

Claims

1. A laser welding method for welding an end of a first linear member and an end of a second linear member adjacent to the first linear member by alternately irradiating the end of the first linear member and the end of the second linear member with laser light, the method comprising: a first step of irradiating the end of the first linear member with the laser light along a first movement path that has a loop shape; a second step of stopping the irradiation of the laser light and moving the irradiation position of the laser light from the end of the first linear member to the end of the second linear member along a second linear movement path; a third step of irradiating the end of the second linear member with the laser light along a third movement path that has a loop shape; a fourth step of stopping the irradiation of the laser light and moving the irradiation position of the laser light from the end of the second linear member to the end of the first linear member along a fourth linear movement path; Equipped with a second movement path that is tangent to the first movement path and the third movement path; a fourth movement path that is in contact with the first movement path and the third movement path at a position opposite to the second movement path; In the first irradiation of the laser light, when the irradiation position of the laser light is moved from the irradiation start position of the laser light at the end of the first linear member in a direction approaching the end of the second linear member, moving the irradiation position of the laser light by one revolution along the first movement path from the irradiation start position of the laser light; A laser welding method in which the irradiation position of the laser light at the end of the second linear member is moved 1.5 times along the third movement path in the same direction as the movement direction of the first movement path.

2. A laser welding method for welding an end of a first linear member and an end of a second linear member adjacent to the first linear member by alternately irradiating the end of the first linear member and the end of the second linear member with laser light, the method comprising: a first step of irradiating the end of the first linear member with the laser light along a first movement path that has a loop shape; a second step of stopping the irradiation of the laser light and moving the irradiation position of the laser light from the end of the first linear member to the end of the second linear member along a second linear movement path; a third step of irradiating the end of the second linear member with the laser light along a third movement path that has a loop shape; a fourth step of stopping the irradiation of the laser light and moving the irradiation position of the laser light from the end of the second linear member to the end of the first linear member along a fourth linear movement path; Equipped with a second movement path that is tangent to the first movement path and the third movement path; a fourth movement path that is in contact with the first movement path and the third movement path at a position opposite to the second movement path; In the first irradiation of the laser light, when the irradiation position of the laser light is moved from the irradiation start position of the laser light at the end of the first linear member in a direction away from the end of the second linear member, moving the irradiation position of the laser light 1.5 times along the first movement path from the irradiation start position of the laser light; A laser welding method in which the irradiation position of the laser light at the end of the second linear member is moved 1.5 times along the third movement path in the same direction as the movement direction of the first movement path.

3. In the first step, the laser light is irradiated from approximately the center of an end of the first linear member in a first direction in which the first linear member and the second linear member are aligned, In the second step, the irradiation of the laser light is stopped at the approximate center of the end of the first linear member in the first direction, and the irradiation position of the laser light is moved to the approximate center of the end of the second linear member in the first direction; 3. The laser welding method according to claim 1, wherein in the fourth step, the irradiation of the laser light is stopped at approximately the center of the end of the second linear member in the first direction.

4. restarting the irradiation of the laser light at a position where the second movement path contacts the third movement path; 4. The laser welding method according to claim 1, wherein the irradiation of the laser beam is resumed at a position where the fourth movement path contacts the first movement path.

5. 5. The laser welding method according to claim 4, wherein the second movement path and the fourth movement path are common circumferential tangents to the first movement path and the third movement path.

6. 6. The laser welding method according to claim 1, wherein the first movement path has the same shape and size as the third movement path.

7. A laser welding method according to any one of claims 1 to 6, wherein at the end of the first linear member, the shortest distance between the outer edge of the laser spot and the outer edge of the end of the first linear member is constant.

8. A laser welding method according to any one of claims 1 to 7, wherein at the end of the second linear member, the shortest distance between the outer edge of the laser spot and the outer edge of the end of the second linear member is constant.

9. A method for manufacturing a rotating electric machine, comprising a step of providing coils in a plurality of slots, the coil includes a plurality of segments; A method for manufacturing a rotating electric machine, wherein in the step of providing the coil, ends of the conductor portions of the plurality of segments are welded by the laser welding method according to any one of claims 1 to 8.

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