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); and a laser irradiator (30) that melts the sites (10) to be welded of the object (11) to be welded by means of the laser beam irradiated from the laser head (31), in which a plurality of fixtures (22) are configured so that the object (11) to be welded can be fixed so that the sites (10) to be welded are linearly and continuously arranged at predetermined intervals. The laser irradiator (30) is configured so as to sequentially melt the plurality of sites (10) to be welded by changing the irradiation angle of the laser beam irradiated from the laser head (31), and the laser welding device is further provided with an inert gas nozzle (41) that simultaneously blows inert gas to the plurality of sites (10) to be welded that are all linearly continuous.

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 portion of an object to be welded by irradiating a laser beam. In this laser welding device, described in Japanese Patent Application Laid-Open No. 7-171690, an outer cylinder covers the laser ejection port in a laser head, into which nitrogen gas is supplied. Nitrogen is blown from the periphery of the ejection port toward the welded portion, thereby preventing the metal melted by the laser irradiation from coming into contact with air and thereby preventing oxidation of the welded portion.

[0003] 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.

[0004] 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

[0005] Using an outer cylinder to cover the laser outlet, as in the laser welding device described in Japanese Patent Application Laid-Open No. 7-171690, is effective for so-called XY laser welding, where the laser head moves toward the weld area and irradiates the laser. However, with so-called galvanometer laser welding, where the laser head's irradiation angle is varied without moving the laser head, the wide laser irradiation range makes it difficult to provide an outer cylinder covering the entire laser irradiation range, making it difficult to blow shielding gas around the laser.

[0006] In particular, when the object to be welded is a rotating motor mounted on an electric vehicle, etc., with a relatively large number of coil segments assembled on the stator core, the ends of the coil segments that are continuous in the radial direction of the stator core are welded one by one. Therefore, it is necessary to repeatedly perform rapid welding, and therefore it is necessary to use a galvanometer laser that changes the laser irradiation angle to perform welding.

[0007] Therefore, even with galvanometer lasers, there is a demand for the development of technology that prevents oxidation of welded parts that occurs during welding.

[0008] An object of the present invention is to provide a laser welding device and a laser welding method that prevent oxidation of a weld portion during welding.

[0009] According to one embodiment of the present invention, a laser welding device comprises: a fixing member that fixes an object to be welded; and a laser irradiator that melts the parts of the object to be welded by irradiating a laser from a laser head, wherein the fixing member is configured to fix the object to be welded in a manner such that a plurality of the parts to be welded are arranged continuously in a straight line at predetermined intervals, and the laser irradiator is configured to change the irradiation angle of the laser irradiated from the laser head so as to melt the plurality of parts to be welded in sequence, and the laser welding device further comprises an inert gas nozzle that simultaneously blows inert gas to all of the plurality of parts to be welded that are continuous in a straight line.

[0010] According to another aspect of the present invention, a laser welding method is provided in which a plurality of locations to be welded arranged continuously in a straight line are welded by sequentially irradiating the locations with laser light while simultaneously blowing an inert gas to all of the locations to be welded. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a cross-sectional view showing a laser welding device according to an embodiment of the present invention, taken along Figure 8 Cross-section view of line AA.

[0012] Figure 2 It is along Figure 1 Cross-sectional view of line BB.

[0013] Figure 3 It is along Figure 1 Cross-sectional view of line EE.

[0014] Figure 4 It is along Figure 8 Cross-sectional view of the CC line.

[0015] Figure 5 It shows the arrangement of the parts to be welded, along Figure 9 Cross-sectional view of DD line.

[0016] Figure 6 This is a front view showing a fixture supporting a stator, which is a workpiece to be welded.

[0017] Figure 7 This is a three-dimensional view of the stator, the object to be welded.

[0018] Figure 8 It is a front view of the laser welding device according to the embodiment of the present invention.

[0019] Figure 9 It is a side view of the laser welding device according to the embodiment of the present invention.

[0020] Figure 10 The figure shows the state of irradiating the laser beam to weld the part to be welded located on the downstream side among a plurality of continuous parts to be welded. Figure 1 The corresponding figure.

[0021] Figure 11 It shows Figure 10 Figure 1 shows the subsequent welding operation.

[0022] Figure 12 It shows Figure 11 Figure 1 shows the subsequent welding operation.

[0023] Figure 13 It shows Figure 12 The figure of the subsequent welding operation is a figure showing a state in which a laser is irradiated and welded on a welding location located on the upstream side among a plurality of consecutive welding locations. DETAILED DESCRIPTION

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

[0025] Figure 8 and Figure 9 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 unit, 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 7 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 6 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 7 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 5 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 6 ).like Figure 5 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 5The 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 5 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 8 and Figure 9 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 8 ).

[0034] like Figure 9 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 4 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 9As 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 6 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 9 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 9 , 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 4 and Figure 9 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 9 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 1 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 Figures 1 to 4 As shown, the laser welding device 20 includes an inert gas nozzle 41 that simultaneously blows inert gas toward all of the plurality of welded locations 10 arranged in a straight line. In this embodiment, the inert gas nozzle 41 is provided on both sides of the plurality of welded locations 10 arranged in a straight line via mounting members 42.

[0047] like Figure 4 As shown, a mounting member 42 is attached to the lifting member 34 below the laser head 31. The mounting member 42 is positioned to surround the emission window 31a of the laser head 31. The mounting member 42 includes side pieces 42a and 42b disposed on either side of the emission window 31a, and a connecting piece 42c connecting the protruding ends of the side pieces 42a and 42b. The base ends of the side pieces 42a and 42b are attached to the lifting member 34.

[0048] like Figure 2 and Figure 3As shown, a pair of inert gas nozzles 41 are provided on the two side pieces 42a and 42b, respectively. The pair of inert gas nozzles 41 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 each welded location 10 from obliquely above.

[0049] The ejection ports of the pair of inert gas nozzles 41 are formed as long holes so as to simultaneously blow the inert gas to all the straight and continuous welding locations 10 ( Figure 1 ).

[0050] like Figure 1 As shown, on the connecting piece 42c of the mounting member 42, a carrier gas nozzle 43 for blowing carrier gas along a plurality of straight-line continuous welded portions 10 is provided between a pair of inert gas nozzles 41, 41. Figure 9 ) on the upper side, a gas suction pipe 44 is provided opposite to the carrier gas nozzle 43, and the gas suction pipe 44 sucks the carrier gas blown out from the carrier gas nozzle 43 and passing through multiple parts 10 to be welded.

[0051] like Figure 3 As shown, the carrier gas nozzle 43 has a horizontally elongated elliptical nozzle opening to blow carrier gas between the pair of inert gas nozzles 41, 41 to block the space between the pair of inert gas nozzles 41, 41. A straightening plate 43a is provided on the lower surface of the carrier gas nozzle 43. This straightening plate 43a guides the carrier gas blown from the carrier gas nozzle 43 along a plurality of straight, continuous portions 10 to be welded.

[0052] Figure 1 The illustrated straightening plate 43a is a plate mounted parallel to the horizontal lower surface of the carrier gas nozzle 43, with its front end protruding from the discharge port of the carrier gas nozzle 43. The front end of the straightening plate 43a is bent upwardly. The angle α of the front end of the straightening plate 43a relative to the horizontal plane is set to between 20 and 60 degrees.

[0053] The flow straightener 43a prevents the carrier gas blown from the carrier gas nozzle 43 from flowing downward and guides it along a plurality of straight, continuous weld locations 10. The flow straightener 43a is configured to regulate the flow of the carrier gas so that the carrier gas blown from the carrier gas nozzle 43 flows straight in the horizontal direction without turbulence and is sucked into the gas suction duct 44.

[0054] An air nozzle 46 is provided on the connecting piece 42c of the mounting member 42 near the laser emission window 31a of the laser head 31 for blowing air in parallel with the carrier gas blown out by the carrier gas nozzle 43. The air nozzle 46 has the same structure as the carrier gas nozzle 43, and therefore its description is omitted.

[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 6 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 8 and Figure 9 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 6 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 8 ).

[0059] When the object to be welded is the stator 11, Figure 5 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 1 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 1As 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, inert gas is blown from the inert gas nozzle 41 toward all of the radially continuous welded portions 10. The inert gas prevents the ends 12a of the coil segments 12, melted by the laser irradiation, from coming into contact with oxygen and being oxidized.

[0062] In particular, in this embodiment, if Figure 2 and Figure 3 As shown, inert gas nozzles 41 are provided on both sides of a plurality of radially continuous weld locations 10, thereby blowing inert gas from both sides of the weld locations 10. This prevents the formation of areas not exposed to the inert gas, and 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.

[0063] During welding, carrier gas is blown out from the carrier gas nozzle 43 to produce Figure 1 The double-dashed arrow in the middle shows an air flow parallel to the radially continuous welded portion 10. In addition, air is blown from the air nozzle 46 in parallel with the carrier gas blown from the carrier gas nozzle 43 near the laser emission window 31a.

[0064] In this state, welding of a plurality of radially continuous locations 10 to be welded is performed sequentially from the downstream side of the flow of the carrier gas generated by the carrier gas nozzle 43. This will be described in detail below.

[0065] First, if Figure 10 As shown, laser welding is performed on the (first) weldable portion 10 located at the most downstream side of the carrier gas flow. Laser irradiation melts the end 12a of the coil segment 12 during welding, generating metal vapor from the melted end 12a. This metal vapor is guided by the carrier gas flow from the carrier gas nozzle 43 and rapidly drawn into the gas suction pipe 44 along with the inert gas from the inert gas nozzle 41, where it is discharged to the outside.

[0066] Therefore, metal vapor generated during welding of the portion to be welded 10 located on the most downstream side can be prevented from entering between the laser head 31 and the portion to be welded 10 , thereby preventing attenuation of the laser light due to the intrusion of the metal vapor.

[0067] After the welding of the welded portion 10 located on the most downstream side is completed, the irradiation angle of the laser irradiated from the laser head 31 is changed, such as Figure 11As shown, the laser is irradiated and welded to the next weldable portion 10 located upstream of the already welded portion 10a (the second one from the downstream side of the carrier gas flow). Metal vapor is generated from the newly melted end 12a of the coil segment 12 by the laser irradiation. Furthermore, metal vapor is also generated from the previously welded portion 10a if cooling is not complete.

[0068] The metal vapor generated from the second welding part 10 that has been newly irradiated with laser light and the welded part 10a located downstream thereof is guided by the airflow blown out from the carrier gas nozzle 43, and together with the inert gas blown out from the inert gas nozzle 41, is quickly sucked into the gas suction pipe 44 and discharged to the outside.

[0069] Therefore, it is possible to prevent metal vapor generated during welding of the second portion 10 to be welded from entering between the laser head 31 and the portion 10 to be welded, thereby preventing attenuation of the laser light due to the intrusion of metal vapor.

[0070] After the welding of the second welded portion 10 from the downstream side is completed, the irradiation angle of the laser irradiated from the laser head 31 is changed, such as Figure 12 As shown, the laser is irradiated and welded to the next weldable portion 10 (the third one from the downstream side of the carrier gas flow) located upstream of the already welded portion 10b. Metal vapor is generated from the newly melted end 12a of the coil segment 12 by the laser irradiation. Furthermore, metal vapor is also generated from the previously welded portions 10a and 10b, if cooling is not complete.

[0071] The metal vapor generated from the third welding part 10 that has been newly irradiated with laser light and the welded parts 10a and 10b located downstream thereof is guided by the airflow blown out from the carrier gas nozzle 43, and together with the inert gas blown out from the inert gas nozzle 41, is quickly sucked into the gas suction pipe 44 and discharged to the outside.

[0072] Therefore, it is possible to prevent metal vapor generated during welding of the third portion 10 to be welded from entering between the laser head 31 and the portion 10 to be welded, thereby preventing attenuation of the laser light due to the intrusion of the metal vapor.

[0073] After the welding of the third welded portion 10 from the downstream side is completed, the irradiation angle of the laser irradiated from the laser head 31 is changed, such as Figure 13 As shown, laser irradiation is performed on the next weldable portion 10 (fourth from the downstream side of the carrier gas flow) located upstream of the already welded portion 10c. In this embodiment, the weldable portion 10 located most upstream is irradiated with laser light. Metal vapor is generated from the newly melted end 12a of the coil segment 12 by laser irradiation. Furthermore, metal vapor is also generated from previously welded portions 10a, 10b, and 10c if cooling is not complete.

[0074] The metal vapor generated from the fourth welding part 10 newly irradiated with laser and the welded parts 10a, 10b, 10c located downstream thereof is guided by the airflow blown out from the carrier gas nozzle 43, and together with the inert gas blown out from the inert gas nozzle 41, is quickly sucked into the gas suction pipe 44 and discharged to the outside.

[0075] Therefore, metal vapor generated during welding of the fourth portion to be welded 10 located on the most upstream side can be prevented from entering between the laser head 31 and the portion to be welded 10 , thereby preventing attenuation of the laser light due to the intrusion of metal vapor.

[0076] As described above, when welding multiple weldable locations 10 by sequentially irradiating the weldable locations 10 with laser light, an airflow is generated along the linearly connected plurality of weldable locations 10, and the weldable locations 10 are sequentially irradiated with laser light from the downstream side of the airflow toward the upstream side. This prevents metal vapor generated from the weldable locations 10 during welding from entering between the laser head 31 and the weldable locations 10.

[0077] Therefore, the laser can be prevented from irradiating the metal vapor generated from the welded portion 10 , thereby improving the reliability of welding of the plurality of welded portions 10 that are continuous in a straight line, ie, the end portions 12 a of the coil segments 12 , and increasing the welding speed.

[0078] Since the carrier gas nozzle 43 is provided with a rectifying plate 43a, the flow direction of the carrier gas flow can be adjusted so that the carrier gas does not come into contact with the welded portion 10. Therefore, the carrier gas blown from the carrier gas nozzle 43 does not need to be an inert gas, and a relatively inexpensive gas such as carbon dioxide gas or air can be used.

[0079] Furthermore, an air nozzle 46 is provided near the emission window 31a of the laser head 31, which blows air in parallel with the carrier gas blown from the carrier gas nozzle 43. Therefore, even if metal vapor passes through the carrier gas flow during welding, the air flow prevents the metal vapor from reaching the vicinity of the emission window 31a. Consequently, attenuation of the laser light caused by the intrusion of metal vapor into the vicinity of the emission window 31a can be avoided.

[0080] After welding of a plurality of radially consecutive welded portions 10, i.e., the ends 12a of the coil segments 12, is completed, the stator 22 is rotated together with the stator 11 so that the next welded portion 10 circumferentially adjacent to the welded portion is positioned below the laser head 31. The plurality of radially arranged welded portions 10 positioned below the laser head 31 are then welded sequentially.

[0081] If such operation is repeated and all the continuous welded parts 10 in the radial and circumferential directions are welded, Figure 7 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.

[0082] According to the above embodiment, the following effects are achieved.

[0083] In the laser welding device 20 , when a plurality of straight continuous weldable portions 10 are sequentially irradiated with laser light for welding, the inert gas nozzle 41 simultaneously blows inert gas to all the weldable portions 10 , thereby preventing oxidation of the weldable portions 10 during welding.

[0084] Furthermore, inert gas nozzles 41 are positioned on both sides of a plurality of linearly connected welded areas 10. Inert gas is blown from both sides of the welded areas 10, thereby preventing the formation of areas not exposed to the inert gas. Consequently, the areas 10 to be welded, which have been melted by laser irradiation, are surrounded by the inert gas, effectively preventing oxidation of the welded areas 10.

[0085] Furthermore, although metal vapor is generated from the welded portion 10 during welding, the carrier gas nozzle 43 generates a carrier gas flow along a plurality of welded portions 10 that are connected in a straight line. This allows the metal vapor generated from the welded portion 10 to be quickly removed during welding, preventing the metal vapor from entering between the laser head 31 and the welded portion 10, thereby preventing laser attenuation.

[0086] Furthermore, an air flow is generated by the air nozzle 46 near the emission window 31a of the laser head 31. This prevents metal vapor from reaching the vicinity of the emission window 31a even if it passes through the carrier gas flow.

[0087] 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.

[0088] Furthermore, in the laser welding method of this embodiment, when welding a plurality of weldable locations 10 arranged in a straight line, laser irradiation is performed sequentially. An airflow is generated along the weldable locations 10, and the laser is sequentially irradiated onto the weldable locations 10 from the downstream side toward the upstream side of the airflow. This prevents metal vapor generated from the weldable locations 10 from entering between the laser head 31 and the weldable locations 10 during welding, thereby attenuating the laser light. Consequently, welding speed and reliability can be increased.

[0089] 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.

[0090] This application claims priority based on Japanese Patent Application No. 2023-12430 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; and A laser irradiation machine melts the desired welding portion of the object by irradiating laser light from a laser head, wherein: The fixing member is configured to fix the object to be welded in such a manner that a plurality of the locations to be welded are arranged in a straight line and continuously at predetermined intervals. The laser irradiation mechanism changes the irradiation angle of the laser irradiated from the laser head to melt the plurality of welded parts in sequence. The laser welding device further includes an inert gas nozzle that simultaneously blows inert gas toward all of the plurality of linearly continuous locations to be welded.

2. The laser welding device according to claim 1, wherein: The inert gas nozzles are respectively arranged on both sides of the plurality of locations to be welded which are continuous in a straight line.

3. The laser welding device according to claim 2, further comprising: The carrier gas nozzle blows out the carrier gas along the plurality of locations to be welded that are continuous in a straight line between the inert gas nozzles provided on both sides of the plurality of locations to be welded.

4. The laser welding device according to claim 3, further comprising: The gas suction pipe sucks the carrier gas blown out from the carrier gas nozzle and passing through the plurality of locations to be welded.

5. The laser welding device according to claim 3, further comprising: A rectifying plate guides the carrier gas blown from the carrier gas nozzle along the plurality of locations to be welded that are continuous in a straight line.

6. The laser welding device according to claim 3, further comprising: The air nozzle is located near the laser emission window of the laser head and blows out air in parallel with the carrier gas blown out by the carrier gas nozzle.

7. The laser welding device according to claim 1, 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.

8. A laser welding method, wherein: While blowing inert gas simultaneously to all of the plurality of welded portions arranged continuously in a straight line, the plurality of welded portions are sequentially irradiated with laser light for welding.

9. The laser welding method according to claim 8, wherein: generating an air flow along the plurality of locations to be welded that are continuous in a straight line, The plurality of locations to be welded that are continuous in a straight line are sequentially irradiated with laser light from the downstream side toward the upstream side of the air flow.

Images