Laser welding device and laser welding method

Abstract

A laser welding device (20) is provided with: a fixture (22) that fixes an object to be welded (11); a laser irradiator (30) that melts a site (10) to be welded of the object (11) to be welded by means of the laser beam irradiated from the laser head (31); inert gas nozzles (41, 42) for blowing an inert gas to the melted site (10) to be welded; a moving mechanism (25) that moves the object (11) to be welded together with the fixture (22) after the laser irradiation machine (30) irradiates the site (10) to be welded with the laser; and a downstream gas nozzle (44) that blows an inert gas to the region (10) to be welded, which has been irradiated with the laser light, after the object (11) to be welded has moved.

Description

Technical Field

[0001] The invention relates to a laser welding device and a laser welding method for welding by irradiating laser. Background Art

[0002] Laser welding devices are known as a means of welding the desired areas of an object. Metal melted by laser irradiation will oxidize if exposed to air before cooling. Therefore, nitrogen gas, for example, is blown over the metal to prevent oxidation.

[0003] Japanese Patent Application Laid-Open No. 7-171690 discloses a device that surrounds a laser nozzle that emits laser light with an outer cylinder and supplies nitrogen gas to the nozzle, blowing the nitrogen gas from the periphery of the nozzle toward the welded area. In this laser welding device, the blown nitrogen gas isolates the welded area from the air, preventing the metal melted by the laser from coming into contact with air.

[0004] Known weld targets for laser welding include rotating electrical machines such as motors, generators, and motor generators used in electric vehicles. The stator of a rotating electrical machine described in Japanese Patent Application Laid-Open No. 2022-36296 is manufactured by arranging coils on a stator core. To achieve relatively high torque, the coils use square wire with a substantially square cross-section.

[0005] In the manufacturing process of this rotating electrical machine, coils are produced using welding equipment. A square wire is formed into a corrugated shape to allow for pre-positioning on the stator core. Multiple corrugated coil segments are pre-positioned on the stator core, and the ends of the multiple coil segments are connected to provide electrical continuity, forming a single coil. The ends of the coil segments are connected using laser welding. Summary of the Invention

[0006] As in the laser welding device described in Japanese Patent Application Laid-Open No. 7-171690, it is effective in the case of so-called XY laser irradiation in which the laser head moves toward the welding portion and irradiates the laser beam.

[0007] However, in the case of XY lasers, after the weld is melted by laser irradiation, if the laser head is moved to the next weld, the nitrogen gas blown to the weld will also move to the next weld. Therefore, if the weld that melted first is not fully cooled, it will come into contact with air and oxidize.

[0008] On the other hand, a so-called galvanometer laser is also known as a laser irradiation machine that changes the irradiation angle of laser light irradiated from a laser head without moving the laser head.

[0009] In the case of a galvanometer laser, it is expected that the laser can be quickly irradiated to multiple weld locations. However, the wide irradiation range of a galvanometer laser makes it difficult to install an outer cylinder that covers the entire laser irradiation range, and preventing oxidation of all weld locations becomes a problem.

[0010] In particular, when the welded object is a rotating electrical machine installed in an electric vehicle or the like, the ends of a relatively large number of coil segments assembled on the stator core are welded sequentially. This requires repeated welding while preventing oxidation of the welded parts, and the development of such technology is highly anticipated.

[0011] An object of the present invention is to provide a laser welding device and a laser welding method that can perform rapid welding while preventing oxidation of a weld portion.

[0012] According to one embodiment of the present invention, a laser welding device comprises: a fixing member that fixes an object to be welded; a laser irradiator that melts a portion of the object to be welded by irradiating laser light from a laser head; an inert gas nozzle that blows inert gas toward the melted portion to be welded; a moving mechanism that moves the object to be welded together with the fixing member after irradiating the portion to be welded with laser light by the laser irradiator; and a downstream gas nozzle that blows inert gas toward the portion to be welded that has been irradiated with laser light after the object to be welded has moved.

[0013] According to another embodiment of the present invention, a laser welding method is provided, in which an object to be welded having a plurality of portions to be welded is moved, and laser welding is performed while blowing inert gas toward the portions to be welded sequentially opposite to the laser head, wherein the inert gas is continuously blown toward the portions to be welded not only during the laser irradiation but also during and after the movement of the object to be welded after the irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a cross-sectional view showing a laser welding device according to an embodiment of the present invention, taken along Figure 10 Cross-section view of line AA.

[0015] Figure 2 It shows the parts to be welded from Figure 1 The state shown in the figure is the state after the state is moved.

[0016] Figure 3 It is along Figure 1 Cross-sectional view of line BB.

[0017] Figure 4 It is along Figure 1 Cross-sectional view of line EE.

[0018] Figure 5 It is along Figure 9 Cross-sectional view of the CC line.

[0019] Figure 6 It shows the arrangement of the parts to be welded, along Figure 10 Cross-sectional view of the DD line.

[0020] Figure 7 This is a front view showing a fixture supporting a stator, which is a workpiece to be welded.

[0021] Figure 8 This is a three-dimensional view of the stator, the object to be welded.

[0022] Figure 9 It is a front view of the laser welding device according to the embodiment of the present invention.

[0023] Figure 10 It is a side view of the laser welding device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0025] Figure 9 and Figure 10 The laser welding device 20 according to the embodiment of the present invention is shown. The laser welding device 20 includes a fixing member 22 as a fixing means, which fixes the object to be welded inside the housing 21. The object to be welded in this embodiment is a stator 11 of a rotating electric machine mounted on an electric vehicle, etc. Figure 8 The inner rotor type stator 11 is shown. In the present invention, the object to be welded is not limited to the stator 11.

[0026] The stator 11 is composed of multiple coil segments 12 arranged in a stator core 13. Each coil segment 12 is shaped like a wave, allowing insertion of square wires with a roughly square cross-section into slots. The slots extend axially along the inner circumference of the stator core 13. The coil segments 12 are inserted into the slots with their ends 12a positioned upward.

[0027] Figure 7 The figure shows a fixture 22 for fixing a stator 11 having a plurality of coil segments 12 and a stator core 13 to which the plurality of coil segments 12 are attached. The fixture 22 supports and fixes the stator 11 so that the central axis of the stator 11 is oriented in a vertical direction.

[0028] The fixing part 22 of this embodiment includes: a base plate 22a; a core support plate 22c, which is arranged on the base plate 22a via a short support 22b, and has the end face (lower surface) of the stator core 13 placed on the upper surface to support the stator core 13 from below; a core pressure plate 22e, which is arranged on the core support plate 22c via a middle support 22d, and clamps the stator core 13 together with the core support plate 22c; and a holding plate 23, which is arranged on the core pressure plate 22e via an upper support 22f.

[0029] With the stator core 13 sandwiched between the core support plates 22c and the core pressure plates 22e, the ends 12a of the coil segments 12 disposed on the stator core 13 protrude upward from the upper surface of the stator core 13. The holding plates 23 hold and secure the ends 12a of the plurality of coil segments 12 protruding from above the stator core 13, enabling the ends 12a of the coil segments 12 to be positioned for welding.

[0030] Here, if Figure 8 As shown, in the stator 11 to be welded, the coil segments 12 are arranged in a state where multiple coil segments 12 are arranged circumferentially on the stator core 13 and overlapped in the radial direction. The pair of overlapping end portions 12a become the welded portions 10 to be welded. Figure 6 As shown, multiple welded areas 10 (a pair of end portions 12a) are arranged in a straight line at predetermined intervals in a radial direction passing through the rotation center of the stator 11. Furthermore, these radially continuous welded areas 10 are also arranged in a continuous circumferential direction. A holding plate 23 secures all of the welded ends 12a. Thus, the fixture 22 secures the workpiece so that the multiple welded areas 10 are arranged in a straight line at predetermined intervals.

[0031] The holding plate 23 includes two overlapping upper holding plates 23a and lower holding plates 23b (see Figure 7 ).like Figure 6 As shown, the upper holding plate 23a and the lower holding plate 23b are respectively formed with holes 23c and 23d, through which the ends 12a of a pair of coil segments 12 are inserted in an overlapping state. Hole 23c comprises a large hole 23ca having a larger width in the radial direction of the stator 11, a small hole 23cb having a smaller width in the radial direction of the stator 11 than the large hole 23ca, and a connecting hole 23cc connecting the large hole 23ca and the small hole 23cb. Hole 23d has the same shape as hole 23c, and similarly comprises a large hole 23da, a small hole 23db, and a connecting hole 23dc. Multiple holes 23c and 23d are formed at predetermined intervals in the radial direction of the stator 11, and multiple holes 23c and 23d are also formed at predetermined intervals in the circumferential direction. Holes 23c and 23d are formed in opposite directions. Figure 6The diagram shows a state in which the small hole 23cb of the hole 23c communicates with the small hole 23db of the hole 23d in the axial direction of the stator 11, and the pair of overlapping end portions 12a are inserted through the small holes 23cb and 23db.

[0032] The upper holding plate 23a and the lower holding plate 23b are configured to be rotatable in opposite directions to each other. From a state in which one of the pair of end portions 12a is located in the large hole 23ca of the hole 23c of the upper holding plate 23a and the other of the pair of end portions 12a is located in the large hole 23da of the hole 23d of the lower holding plate 23b, the upper holding plate 23a and the lower holding plate 23b are rotated in opposite directions to each other. Thus, one of the pair of end portions 12a is guided from the connecting hole 23cc to the small hole 23cb in the hole 23c of the upper holding plate 23a and abuts against the end of the small hole 23cb, and the other of the pair of end portions 12a is guided from the connecting hole 23dc to the small hole 23db in the hole 23d of the lower holding plate 23b and abuts against the end of the small hole 23db. As a result, as Figure 6 As shown, the pair of end portions 12a are inserted through the small holes 23cb and 23db, in close contact with each other, and positioned in the circumferential direction of the stator 11. In this way, a plurality of weldable portions 10 (a pair of end portions 12a) are arranged continuously at predetermined intervals in the radial direction of the stator 11, and the plurality of weldable portions 10 arranged continuously in the radial direction are also arranged continuously in the circumferential direction.

[0033] like Figure 9 and Figure 10 As shown, a rotating table 24 for mounting the fixing member 22 is provided on the housing 21. The housing 21 comprises: a lower body 26 having mounting feet 26a mounted on the lower portion thereof and surrounded by a peripheral wall 26b; a welding area 27 provided on the upper portion of the lower body 26; and an upper body 28 further provided on the upper portion of the welding area 27 and having an operation panel 28a, a display 28b, etc. provided on the front surface thereof ( Figure 9 ).

[0034] like Figure 10 As shown, a back panel 27b is provided on the back of the welding area 27. The back panel 27b is provided upright on the upper portion of the back of the lower body 26, and pillars 27a are provided upright on both sides of the upper portion of the front surface of the lower body 26. A light-transmitting resin door 27c is attached to the pillars 27a via hinges 27d. The door 27c is configured to be able to open and close between the pillars 27a. Figure 5 As shown, the space between the side surface of the rear panel 27b and the support column 27a is closed by a light-transmitting side wall 27e, so that the interior can be visually checked.

[0035] like Figure 10As shown, the rotating table 24 is horizontally mounted on the upper end of a vertical shaft 24a, which is vertically supported within the lower body 26. The rotating table 24 is positioned at the boundary between the lower body 26 and the welding area 27. The upper surface of the rotating table 24 is formed into a flat surface to accommodate the table 22a of the fixture 22. Pins 24b for positioning the table 22a are provided upward on the upper surface of the rotating table 24.

[0036] like Figure 7 As shown, a pin hole 22g for inserting a pin 24b is formed on the base plate 22a of the fixing member 22. By inserting the pin 24b into the pin hole 22g of the base plate 22a, the fixing member 22 is set at the correct position of the rotating table 24.

[0037] like Figure 10 As shown, the laser welding device 20 of this embodiment includes a moving mechanism 25 as a moving means that rotates the stator 11 together with the stator 22. The moving mechanism 25 includes a motor 29 provided on the lower body 26 adjacent to the rotating table 24; sprockets 24c and 29b provided on the vertical shaft 24a of the rotating table 24 and the rotating shaft 29a of the motor 29, respectively; and a chain 29c connecting the sprockets 24c and 29b.

[0038] When the motor 29 is driven to rotate the rotating shaft 29 a , the rotation is transmitted to the rotating table 24 via the chain 29 c , so that the stator 22 placed on the rotating table 24 and the stator 11 fixed to the stator 22 are rotated.

[0039] The fixing member 22 is coaxially provided on the rotating table 24. By rotating the fixing member 22 by the motor 29, the locations to be welded 10 arranged continuously in the circumferential direction are moved in the circumferential direction.

[0040] The laser welding apparatus 20 includes a laser irradiator 30. The laser irradiator 30 includes a laser head 31 mounted above the stator 22 and the stator 11. The laser irradiator 30 melts the desired portion of the workpiece using laser light emitted from the laser head 31. The laser irradiator 30 includes a laser oscillator (not shown); an optical fiber that forms an optical path for transmitting the generated laser light; and the laser head 31, which incorporates a focusing system that focuses the laser light transmitted via the optical fiber and then irradiates the workpiece.

[0041] In this embodiment, if Figure 10 , a method of mounting the laser head 31 via a lifting mechanism 32 serving as a lifting means is shown. The lifting mechanism 32 will now be described. A pair of linear motion guide rails 33 are mounted on the rear panel 27b of the welding area 27 of the housing 21, extending vertically at predetermined intervals in the width direction. A lifting member 34 is mounted on the linear motion guide rails 33 so as to be movable up and down.

[0042] like Figure 5 and Figure 10 As shown, a vertical rotation shaft 35 is rotatably provided between the pair of linear motion guide rails 33 and parallel to the pair of linear motion guide rails 33. The surface of the vertical rotation shaft 35 is provided with an external thread, and a vertical movement portion 36 is screwed onto the vertical rotation shaft 35 via a ball screw. The vertical movement portion 36 is attached to the lifting member 34.

[0043] like Figure 10 As shown, a vertical drive source 37 is disposed on the back panel 27b to rotationally drive the vertical rotation shaft 35. A servo motor capable of high-precision control is used as the vertical drive source 37. As the vertical rotation shaft 35 is rotated by the vertical drive source 37, the vertical moving portion 36 screwed therewith is raised and lowered together with the lifting member 34.

[0044] The housing of the laser head 31 is box-shaped and is mounted on the lifting member 34. An emission window 31a ( Figures 1 to 3 ) Inside the laser head 31, a reflecting device is provided together with a focusing system.

[0045] The laser irradiation machine 30 can change the irradiation direction by reflecting the laser light inside the laser head 31. Figure 3 As shown by the dotted arrow, the laser irradiator 30 is configured to move the laser emitted from the laser head 31 along the radial direction of the fixing member 22, so that the pair of end portions 12a of the coil segments 12, which are arranged in the radial direction and need to be welded, can be welded in sequence.

[0046] like Figure 1 、 Figure 2 and Figure 5 As shown, the laser welding apparatus 20 includes inert gas nozzles 41 and 42 that simultaneously blow inert gas toward all of the plurality of welded locations 10 arranged in a straight line. In this embodiment, the inert gas nozzles 41 and 42 are disposed on either side of the plurality of welded locations 10 arranged in a straight line via mounting members 43.

[0047] like Figure 5 As shown, a mounting member 43 is attached to the lifting member 34 below the laser head 31. The mounting member 43 is positioned to surround the emission window 31a of the laser head 31. The mounting member 43 includes side pieces 43a and 43b positioned on either side of the emission window 31a, and a connecting piece 43c connecting the protruding ends of the side pieces 43a and 43b. The base ends of the side pieces 43a and 43b are attached to the lifting member 34.

[0048] like Figure 1and Figure 2 As shown, a pair of inert gas nozzles 41 and 42 are provided on the two side pieces 43a and 43b, respectively. The pair of inert gas nozzles 41 and 42 are arranged so as to sandwich a plurality of welded locations 10 from both upstream and downstream sides of a continuous linear line of welded locations 10 in the radial direction of the stator 11 in the rotational direction. The nozzles are arranged at an angle so as to spray inert gas onto the welded locations 10 from obliquely above.

[0049] The nozzles of the pair of inert gas nozzles 41 and 42 are formed as long holes so as to simultaneously blow the inert gas to all the straight and continuous welding parts 10 ( Figure 3 ).

[0050] The laser welding device 20 includes: a moving mechanism 25 that moves the stator 11 fixed by the fixing member 22 after the laser irradiation device 30 irradiates the portion to be welded 10 with laser light; and a downstream gas nozzle 44 that moves the stator 11 toward the portion to be welded 10 ( Figure 1 In the present embodiment, the moving mechanism 25 is a rotation moving mechanism as a rotation moving means, which rotates the stator 11 in a horizontal plane.

[0051] The downstream gas nozzle 44 is mounted on the mounting member 43. Figure 1 As shown, the downstream gas nozzle 44 is mounted on the side piece 43b of the mounting member 43 via a brace 46, in parallel with the inert gas nozzle 42 located downstream in the rotational direction (movement direction) of the stator 11. After the stator 11 rotates and moves, the downstream gas nozzle 44 blows inert gas from the downstream side toward the upstream side in the rotational direction of the stator 11 toward the laser-irradiated portion 10 to be welded. The downstream gas nozzle 44 is positioned at an angle so that the inert gas is blown diagonally upward toward the laser-irradiated portion 10 to be welded.

[0052] The ejection port of the downstream gas nozzle 44 is formed as a long hole ( Figure 4 ) so as to simultaneously blow the inert gas to all radially continuous straight-line locations 10 to be welded.

[0053] A shielding plate 47 is provided between the downstream inert gas nozzle 42 and the downstream gas nozzle 44. Specifically, the shielding plate 47 is attached to the downstream gas nozzle 44. The shielding plate 47 is adjusted to block the flow of the inert gas blown out of the downstream gas nozzle 44 on the upstream side in the rotation direction so that the inert gas blown out of the downstream gas nozzle 44 does not interfere with the inert gas blown out of the inert gas nozzles 41 and 42.

[0054] That is, the shielding plate 47 of this embodiment separates the downstream inert gas nozzle 42 and the downstream gas nozzle 44 , and prevents the inert gas blown from the downstream gas nozzle 44 from excessively intruding into the upstream side.

[0055] Next, a welding method using the laser welding device 20 will be described.

[0056] In this embodiment, the object to be welded is Figure 7 The stator 11 of the rotating electrical machine shown has a plurality of corrugated coil segments 12 pre-arranged on a stator core 13, and the ends 12a of the plurality of coil segments 12 are welded to provide electrical continuity using a laser welding device 20. This will be described in detail below.

[0057] First, the stator core 13 with the coil segments 12 is mounted on the fixing member 22. Figure 7 As shown, the stator core 13 is placed on the core support plate 22c, and the stator core 13 is sandwiched between the core support plate 22c and the core pressure plate 22e. Then, as described above, the holding plates 23 hold and secure the portions 10 to be welded, i.e., the pair of end portions 12a, of the coil segments 12 protruding from the upper portion of the stator core 13.

[0058] Next, the fixing member 22 with the stator 11 mounted thereon is mounted on the rotating table 24. Figure 9 and Figure 10 As shown, the door 27c of the housing 21 is opened, and the pin 24b of the rotating table 24 is inserted into the pin hole 22g of the table 22a, thereby setting the table 22a of the fixing member 22 on the rotating table 24 ( Figure 7 Then, the door 27c is closed and the welding operation is started. The welding operation is performed by operating the operation panel 28a in the upper body 28 ( Figure 9 ).

[0059] When the object to be welded is the stator 11, Figure 6 As shown, the coil segment 12 has multiple weldable areas 10 (a pair of end portions 12a) arranged radially, and multiple weldable areas 10 arranged radially are also arranged circumferentially. The laser welding device 20 welds the weldable areas 10 arranged in this manner as follows. First, the laser irradiator 30 welds the multiple weldable areas 10 arranged radially in sequence. Then, the stator 22 rotates together with the stator 11 so that the next weldable area 10 circumferentially adjacent to the welded area is positioned below the laser head 31. The laser irradiator 30 then welds the multiple weldable areas 10 arranged radially below the laser head 31 in sequence. This process is repeated to weld the weldable areas 10.

[0060] like Figure 3 As shown, the welding of a plurality of continuous welded portions 10 in the radial direction is performed by sequentially irradiating the welded portions 10 with laser light from the laser irradiator 30. Figure 3 As shown by the dotted arrow, the laser irradiation machine 30 does not move the laser head 31, but moves the laser emitted from the laser head 31 along the radial direction of the fixing member 22 to weld a plurality of radially continuous welded portions 10 in sequence.

[0061] When welding a plurality of radially continuous welded portions 10, as shown in FIG. Figure 1 As shown, inert gas is blown from inert gas nozzles 41 and 42 to all radially continuous locations 10 to be welded. This inert gas prevents the ends 12a of the coil segments 12 melted by laser irradiation from coming into contact with oxygen and being oxidized.

[0062] After the welding of the plurality of radially continuous welded portions 10 is completed, the moving mechanism 25 ( Figure 10 ) Make the stator 11 and the fixing member 22 together as Figure 2 The stator 11 is rotated as indicated by the solid arrow in the figure, thereby positioning the next welded portion 10 adjacent to the welded portion 10a in the circumferential direction below the laser head 31. The rotation of the stator 11 is then stopped. The plurality of welded portions 10 arranged radially below the laser head 31 are then welded sequentially.

[0063] Thus, in the welding method using the laser welding device 20, the stator 11 is moved so that the parts to be welded 10 are sequentially opposed to the laser head 31, and the parts to be welded 10 sequentially opposed to the laser head 31 are irradiated with laser light to melt them while blowing inert gas.

[0064] The laser welding method of this embodiment is characterized in that an inert gas is continuously blown toward the melted portion to be welded 10 not only during laser irradiation but also during and after the movement of the stator 11 after laser irradiation.

[0065] As described above, the blowing of the inert gas during the melting period by the laser irradiation is performed by the inert gas nozzles 41 and 42. In this embodiment, Figure 1 As shown, inert gas nozzles 41 and 42 are provided on both sides of a plurality of linearly connected weld locations 10, respectively. This allows inert gas to be blown from both sides of the weld locations 10. This prevents the formation of areas not exposed to the inert gas. Consequently, the areas around the weld locations 10 (ends 12a of the coil segments 12) that are melted by laser irradiation are covered with inert gas, effectively preventing oxidation of the weld locations 10 during laser irradiation. In other words, oxidation of the weld locations 10 during the melting phase caused by laser irradiation can be effectively prevented.

[0066] In this embodiment, the downstream gas nozzle 44 is provided separately from the inert gas nozzles 41 and 42 . Therefore, the inert gas blown out from the downstream gas nozzle 44 may interfere with the inert gas blown out from the inert gas nozzles 41 and 42 .

[0067] However, a shielding plate 47 is provided between the downstream inert gas nozzle 42 and the downstream gas nozzle 44. This prevents the inert gas blown from the downstream gas nozzle 44 from interfering with the inert gas blown from the inert gas nozzles 41 and 42. Consequently, the area around the portion to be welded 10 (the end portion 12a of the coil segment 12) that is melted by the laser irradiation is reliably covered by the inert gas blown from the inert gas nozzles 41 and 42.

[0068] like Figure 2 As shown, the inert gas is blown while the molten welded portion 10 is moving, both by the inert gas nozzles 41 and 42 and the downstream gas nozzle 44. As a result, the inert gas blown from the inert gas nozzles 41 and 42 and the downstream gas nozzle 44 fills the path of the welded portion 10, allowing the welded portion 10 to move along the path filled with inert gas. This prevents oxidation caused by contact with oxygen if the welded portion 10 is not completely cooled.

[0069] In this embodiment, the downstream gas nozzle 44 blows the inert gas diagonally upward from the downstream side toward the upstream side in the rotational direction of the stator 11. Therefore, the inert gas blown from the downstream gas nozzle 44 is directed upstream. As a result, the inert gas blown from the downstream gas nozzle 44 is directed between the upstream inert gas nozzles 41 and 42, allowing the inert gas to fill the travel path of the portion 10 to be welded.

[0070] A shielding plate 47 is provided between the downstream inert gas nozzle 42 and the downstream gas nozzle 44. Therefore, the inert gas blown from the downstream gas nozzle 44 toward the upstream side stays near the shielding plate 47. This prevents turbulence in the inert gas blown from the inert gas nozzles 41 and 42, and the inert gas blown from the downstream gas nozzle 44 fills the moving path of the portion to be welded 10. This prevents oxidation of the moving portion to be welded 10 due to contact with oxygen.

[0071] like Figure 1As shown, the inert gas is blown through the downstream gas nozzle 44 after the welded portion 10 (welded portion 10a) has moved. Specifically, the downstream gas nozzle 44 blows the inert gas toward the laser-irradiated portion 10 (welded portion 10a) after the stator 11 has moved. This prevents oxidation caused by contact with oxygen when the welded portion 10 (welded portion 10a) is still molten and has not yet fully cooled.

[0072] Typically, after the portion to be welded 10 is melted by laser irradiation while blowing inert gas, if the portion to be welded 10 is moved, the blowing of inert gas toward the portion to be welded 10 will cease. In this case, if the melted portion to be welded 10 has not completely cooled, it will come into contact with air and oxidize.

[0073] However, in the laser welding method of this embodiment, an inert gas is continuously blown toward the laser-melted portion 10 during the melting period, the movement period, and the period after the movement due to laser irradiation. This prevents the portion 10 from coming into contact with air before cooling is complete, thereby preventing oxidation of the portion 10.

[0074] As a result, the portion to be welded 10 can be moved before the cooling of the melted portion to be welded 10 is completed. Figure 1 As shown, the portion to be welded 10 that is subsequently moved to the bottom of the laser head 31 can be re-irradiated with laser light for welding, so rapid welding can be performed.

[0075] In particular, if the time for blowing inert gas toward the portion to be welded 10 (welded portion 10a) that has been irradiated with laser light after the stator 11 moves is set to be equal to or longer than the time for irradiating the portion to be welded 10 with laser light before the stator 11 moves, the portion to be welded 10 can be irradiated with laser light while inert gas is continuously blown out from the inert gas nozzles 41, 42 and the downstream gas nozzle 44, thereby continuously welding the portion to be welded 10, and rapid and oxidation-free welding can be performed.

[0076] By using a laser irradiation machine 30 that sequentially melts a plurality of radially continuous weld locations 10 by varying the irradiation angle of the laser beam emitted from a laser head 31, it is possible to rapidly weld a plurality of radially and circumferentially continuous weld locations 10. Therefore, even when the welded object is a rotating electrical machine such as an electric vehicle, in which a relatively large number of coil segments 12 are assembled into a stator core 13, rapid welding can be performed while preventing oxidation of the coil segment ends 12a.

[0077] In the case of a rotating electrical machine, if such operation is repeated and all the continuous welded portions 10 in the radial and circumferential directions are welded, then Figure 8 As shown, in the state of being arranged on the stator core 13, the ends 12a of the plurality of coil segments 12 are electrically connected to form a single coil. Then, the stator core 13 is removed from the fixing member 22, and a series of welding operations are completed.

[0078] In the above embodiment, the shielding plate 47 is attached to the downstream gas nozzle 44. However, this is merely an example, and the shielding plate 47 may be attached to either the mounting member 43 or the downstream inert gas nozzle 42, as long as it does not interfere with the inert gas blown from the inert gas nozzles 41 and 42.

[0079] In the above embodiment, a shielding plate 47 is provided between the downstream inert gas nozzle 42 and the downstream gas nozzle 44. However, the shielding plate 47 may be omitted if the inert gas blown from the inert gas nozzles 41 and 42 is not interfered with by the inert gas blown from the downstream gas nozzle 44.

[0080] According to the above embodiment, the following effects are achieved.

[0081] The laser welding apparatus 20 is equipped with a downstream gas nozzle 44 that blows an inert gas toward the welded portion 10 (welded portion 10a) after the stator 11 (the object to be welded) moves. This inert gas is continuously blown toward the welded portion 10 not only during laser irradiation but also during and after the movement of the stator 11 (the object to be welded) after irradiation. This prevents the welded portion 10, which has been melted by laser irradiation, from coming into contact with oxygen and oxidizing before cooling.

[0082] In addition, the downstream gas nozzle 44 blows inert gas from the downstream side of the rotation direction (movement direction) of the stator 11 (object to be welded) toward the upstream side from obliquely above, so that the inert gas blown out from the downstream gas nozzle 44 can fill the moving path of the part to be welded 10.

[0083] Furthermore, a shielding plate 47 is provided between the downstream inert gas nozzle 42 and the downstream gas nozzle 44. Therefore, the inert gas blown from the downstream gas nozzle 44 toward the upstream side stays near the shielding plate 47. This prevents turbulence in the inert gas blown from the inert gas nozzles 41 and 42, and the moving path of the welded portion 10 is filled with inert gas, thereby preventing oxidation caused by contact with oxygen during the movement of the welded portion 10.

[0084] In addition, if the time for blowing inert gas toward the portion to be welded 10 (welded portion 10a) that has been irradiated with laser light after the stator 11 (object to be welded) moves is set to be equal to or longer than the time for irradiating the portion to be welded 10 with laser light before the stator 11 (object to be welded) moves, the portion to be welded 10 can be irradiated with laser light while inert gas is continuously blown out from the inert gas nozzles 41, 42 and the downstream gas nozzle 44, thereby continuously welding the portion to be welded 10, and rapid and oxidation-free welding can be performed.

[0085] As described above, the laser welding apparatus 20 of this embodiment enables rapid welding while preventing oxidation of the welded portions 10. When the workpiece is a stator 11 in which coil segments 12 are mounted in slots in a stator core 13, the welded portions 10 are the ends 12a of the coil segments 12, resulting in a relatively large number of welded portions 10. However, the laser welding apparatus 20 of this embodiment enables rapid welding of the ends 12a of the coil segments 12, significantly reducing the manufacturing time of the stator 11 for a rotating electrical machine.

[0086] While the embodiments of the present invention have been described above, the above embodiments merely illustrate some application examples of the present invention and do not limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0087] This application claims priority based on Japanese Patent Application No. 2023-12431 filed with the Japan Patent Office on January 31, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A laser welding device comprising: A fixing member that fixes the object to be welded; A laser irradiation machine, which melts the desired welding portion of the object by irradiating laser light from a laser head; an inert gas nozzle for blowing inert gas toward the melted portion to be welded; a moving mechanism that moves the object to be welded together with the fixing member after the laser irradiation machine irradiates the portion to be welded with laser light; and The downstream gas nozzle blows an inert gas toward the portion to be welded that has been irradiated with the laser beam after the workpiece moves.

2. The laser welding device according to claim 1, wherein: The downstream gas nozzle blows an inert gas from the downstream side toward the upstream side in the moving direction of the workpiece.

3. The laser welding device according to claim 2, wherein: The inert gas nozzles are respectively arranged on both the upstream side and the downstream side of the moving direction of the welded object. A shielding plate is provided between the inert gas nozzle provided on the downstream side and the downstream gas nozzle.

4. The laser welding device according to claim 1, wherein: The moving mechanism is a rotational moving mechanism that rotates the workpiece fixed by the fixing member within a horizontal plane.

5. The laser welding device according to claim 4, wherein: The fixing member is configured to fix the workpiece in such a manner that a plurality of the locations to be welded are continuously arranged at predetermined intervals in a radial direction passing through a rotation center of the workpiece, and the plurality of locations to be welded continuously arranged in the radial direction are also continuously arranged at predetermined intervals in a circumferential direction. The laser irradiation mechanism is configured to sequentially melt the plurality of radially continuous locations to be welded by changing an irradiation angle of the laser light irradiated from the laser head.

6. The laser welding device according to claim 5, wherein: The object to be welded is a stator having a stator core and coil segments fitted into slots of the stator core. The portion to be welded is the end of the coil segment.

7. A laser welding method, wherein a workpiece having a plurality of welded portions is moved, and an inert gas is blown toward the welded portions sequentially facing the laser head while the laser is irradiated to perform welding, wherein: Inert gas is continuously blown toward the portion to be welded not only during laser irradiation but also during and after movement of the object to be welded after irradiation.

8. The laser welding method according to claim 7, wherein: The time for blowing the inert gas toward the portion to be welded after the object to be welded moves is equal to or longer than the time for irradiating the portion to be welded with the laser before the object to be welded moves.

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