Laser welding machine and laser welding method for rectangular wires

Abstract

If a gap amount between first and second edges (S1 and S2) of first and second rectangular wires (71 and 72) is 0, this laser welding machine will set a central part of a third edge (S3), which is on the opposite side to the first edge (S1), as an irradiation start position of the laser beam, and irradiate each tip surface of the first and second rectangular wires (71 and 72) over a reference processing distance (L0) at a reference welding speed (V0) with the laser beam to weld the first and second rectangular wires (71 and 72). If the gap amount exceeds 0 and falls within a first range up to the first gap amount, the laser welding machine will set a position, which is offset from the central part of the third edge (S3) to the second rectangular wire (72) side by a distance of 1 / 2 of the gap amount, as the irradiation start position of the laser beam, and irradiate each tip surface of the first and second rectangular wires (71 and 72) over the reference processing distance (L0) at the reference welding speed (V0) with the laser beam to weld the first and second rectangular wires (71 and 72).

Description

Laser welding machine and laser welding method for rectangular wire

[0001] The present disclosure relates to a laser welder and a method for laser welding rectangular wires.

[0002] In motors used in electric or hybrid vehicles, multiple U-shaped segment coils attached to a core have their ends, adjacent to each other, welded together using a laser welder (see Patent Documents 1 and 2). The ends of the radially adjacent segment coils are made of a pair of rectangular wires.

[0003] JP 2018-20340 A International Publication No. 2019 / 159737

[0004] When a pair of rectangular wires is welded using a laser welding machine, if the corners (edges) of the rectangular wires remain or if the fused portion formed by the melted ends of the pair of rectangular wires bulges excessively, this results in a defective weld. The former is caused by insufficient melting of the metal at the end, while the latter is caused by excessive melting of the metal at the end. A defective weld also occurs when the fused portion is biased toward one of the pair of rectangular wires. If there is a defective weld in the welded pair of rectangular wires, the end cap that should be attached to the end cannot be attached, resulting in a defective motor.

[0005] There is a need for a laser welding machine and a laser welding method for flat wire that can weld a pair of flat wires without leaving any corners of the flat wire, without the molten part expanding excessively, and without the molten part being biased towards one of the pair of flat wires.

[0006] A first aspect of one or more embodiments includes a sensor that measures a gap amount between a first side of the first flat wire and a second side of the second flat wire that face each other at the tip end surfaces of the first and second flat wires that are adjacent to each other to be welded, and a control device that controls the irradiation position of a laser beam that is irradiated onto the first and second flat wires and the movement of the laser beam to weld the first and second flat wires, and if the gap amount measured by the sensor is 0, the control device determines that the gap amount at the tip end surface of the first flat wire is 0. The center of a third side opposite to the first side is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to a reference welding speed, and the laser beam is moved from the irradiation start position along a moving direction perpendicular to the first and third sides by a reference processing distance up to the middle part of the tip surface of the second rectangular wire to weld the first and second rectangular wires, and if the gap amount measured by the sensor exceeds 0 and is within a first range up to the first gap amount, 1 / 2 of the gap amount from the center of the third side is welded. The laser beam is then moved from the irradiation start position by a first offset amount, which is a distance of 0, along a moving direction perpendicular to the first and third sides to weld the first and second flat wires. If the gap amount measured by the sensor is within a second range exceeding the first gap amount to a second gap amount, the laser beam is then moved from the irradiation start position by a first offset amount, which is a distance of 0, along a moving direction perpendicular to the first and third sides to weld the first and second flat wires. If the gap amount measured by the sensor is within a second range exceeding the first gap amount to a second gap amount, the laser beam is then moved from the irradiation start position by a first offset amount, which is a distance of 0, along a moving direction perpendicular to the first and third sides to weld the first and second flat wires. If the gap amount measured by the sensor is within a third range exceeding the second gap amount, the laser beam is then moved from the irradiation start position by a first offset amount, which is a distance of 0, along a moving direction perpendicular to the first and third sides to weld the first and second flat wires.A laser welder is provided which controls the laser beam to be irradiated at a position offset from the center of the third side toward the second rectangular wire by a first offset amount, which is half the distance of the gap amount, and which sets the moving speed of the laser beam to a welding speed faster than the reference welding speed, and moves the laser beam from the irradiation start position along a moving direction perpendicular to the first and third sides by a processing distance longer than the reference processing distance to weld the first and second rectangular wires.

[0007] In a second aspect of one or more embodiments, a gap amount between a first side of the first flat wire and a second side of the second flat wire, which are opposed to each other at the tip end surfaces of first and second flat wires to be welded adjacent to each other, is measured by a sensor, and if the gap amount measured by the sensor is 0, the center of a third side of the tip end surface of the first flat wire, which is opposite to the first side, is set as a laser beam irradiation start position, and the moving speed of the laser beam is set to a reference welding speed, and the laser beam is irradiated from the irradiation start position to the first and third flat wires. the first and second flat wires are welded by moving the second flat wire along a moving direction perpendicular to the third side by a standard processing distance up to the middle part of the tip surface of the second flat wire, and if the gap amount measured by the sensor exceeds 0 and is within a first range up to a first gap amount, a position offset from the center of the third side toward the second flat wire by a first offset amount which is a distance of 1 / 2 of the gap amount is set as the irradiation start position of the laser beam, and the moving speed of the laser beam is set to the standard welding speed, and the laser beam is welded from the irradiation start position by a first offset amount which is a distance of 1 / 2 of the gap amount the first and second flat wires are welded by moving the reference processing distance along a moving direction perpendicular to the first and third sides from the center of the third side, and if the gap amount measured by the sensor is within a second range exceeding the first gap amount to a second gap amount, the position offset from the center of the third side to the second flat wire by a distance obtained by adding a first offset amount, which is half the distance of the gap amount, and a predetermined second offset amount exceeding 0 is set as the irradiation start position of the laser beam, and the moving speed of the laser beam is set to the reference welding speed, The laser beam is moved from the irradiation start position by the reference processing distance along a movement direction perpendicular to the first and third sides to weld the first and second rectangular wires, and if the gap amount measured by the sensor is within a third range exceeding the second gap amount, a position offset from the center of the third side toward the second rectangular wire by a first offset amount, which is half the distance of the gap amount, is set as the irradiation start position of the laser beam, and the movement speed of the laser beam is set to a welding speed faster than the reference welding speed,The present invention provides a laser welding method for flat wires, which welds the first and second flat wires by moving the first and second flat wires from the irradiation start position along a movement direction perpendicular to the first and third sides by a processing distance longer than the reference processing distance.

[0008] According to one or more embodiments of the laser processing machine and the laser welding method for flat square wire, a pair of flat square wires can be welded without leaving any edges of the flat square wire, without the molten part expanding excessively, and without the molten part being biased towards one of the pair of flat square wires.

[0009] FIG. 1 is a diagram showing a laser processing machine according to one or more embodiments. FIG. 2 is a perspective view showing a galvanometer scanner that may be included in the laser processing machine according to one or more embodiments. FIG. 3 is a plan view showing a pair of flat wires in contact with each other. FIG. 4 is a plan view showing a pair of flat wires spaced apart from each other. FIG. 5 is a diagram showing a first comparative example to be compared with the laser welding method for flat wires according to one or more embodiments. FIG. 6 is a diagram showing a second comparative example to be compared with the laser welding method for flat wires according to one or more embodiments. FIG. 7 is a diagram showing a third comparative example to be compared with the laser welding method for flat wires according to one or more embodiments. FIG. 8 is a diagram showing a laser welding method for flat wires according to one or more embodiments. FIG. 9A is a side view showing a welding defect due to an edge residue. FIG. 9B is a side view showing a welding defect in which the fusion width of the fusion zone is too wide. FIG. 9C is a side view showing a welding defect in which the fusion zone is biased. FIG. 10 is a diagram showing a preferred offset amount when the gap amount between a pair of flat wires is in a first range from 0 mm to a first gap amount. Fig. 11 is a diagram showing a preferred offset amount when the gap amount of a pair of flat wires is in a second range from a first gap amount to a second gap amount. Fig. 12 is a diagram showing the welding conditions and welding results when welding a pair of flat wires. Fig. 13 is a flowchart showing the operation of a laser processing machine according to one or more embodiments and the laser welding method for flat wires according to one or more embodiments.

[0010] Hereinafter, a laser welding machine and a laser welding method for flat wire according to one or more embodiments will be described with reference to the accompanying drawings. First, an example of the overall configuration of a laser processing machine 100 according to one or more embodiments will be described with reference to FIG.

[0011] In FIG. 1 , the blue laser oscillator 10 emits a blue laser beam L10 having a wavelength of, for example, 400 nm or more and 460 nm or less. The blue laser beam L10 is indicated by a dashed line. The blue laser beam L10 is transmitted by a transmission fiber 11 and enters a first housing 41 of the processing head 40. The infrared laser oscillator 20 emits an infrared laser beam L20 having a wavelength of, for example, 1060 nm or more and 1090 nm or less. The infrared laser beam L20 is indicated by a solid line. The infrared laser beam L20 is transmitted by a transmission fiber 21 and enters a second housing 42 of the processing head 40. The infrared laser oscillator 20 can be configured as a fiber laser oscillator.

[0012] The processing head 40 has a first housing 41 and a second housing 42 connected by a connecting portion 43. The first housing 41 houses a collimating lens 411 and a bend mirror 412. The second housing 42 houses a collimating lens 421, a dichroic mirror 423, a focusing lens 424, and a protective glass 425. The collimating lens 411 converts the diverging blue laser beam L10 into collimated light, and the bend mirror 412 reflects the collimated blue laser beam L10 and makes it incident on the dichroic mirror 423. The collimating lens 421 converts the diverging infrared laser beam L20 into collimated light and makes it incident on the dichroic mirror 423.

[0013] The dichroic mirror 423 reflects the blue laser beam L10 and transmits the infrared laser beam L20, thereby emitting a superimposed laser beam in which the two are superimposed on each other. The focusing lens 424 focuses the superimposed laser beam and irradiates it onto the pair of flat wires 71 and 72 to be welded through a protective glass 425. Although not shown in Figure 1, a nozzle is attached to the processing head 40, and the superimposed laser beam is irradiated onto the flat wires 71 and 72 through an opening formed in the nozzle.

[0014] The flat wires 71 and 72 are both ends of a copper segment coil. The flat wire 71 is a first flat wire, and the flat wire 72 is a second flat wire. The collimator lens 421 is preferably configured to be movable in the optical axis direction of the infrared laser beam L20 by a collimator lens drive motor 422.

[0015] The NC device 30 controls the emission of the blue laser beam L10 from the blue laser oscillator 10 and the emission of the infrared laser beam L20 from the infrared laser oscillator 20. The NC device 30 controls the movement of the collimator lens 421 by the collimator lens drive motor 422. The processing head 40 is configured to be freely moved by the movement mechanism 60 in five axes: the x, y, and z directions, the rotational direction, and the tilt direction, which are mutually perpendicular within a plane perpendicular to the traveling direction of the superimposed laser beam. The NC device 30 controls the movement of the processing head 40 by the movement mechanism 60. As described below, the NC device 30 controls the irradiation position and movement of the laser beam irradiated onto the rectangular wires 71 and 72 to weld the rectangular wires 71 and 72. The NC device 30 is an example of a control device that controls each part of the laser processing machine 100.

[0016] A camera 50 is attached to, for example, the side of the processing head 40. The camera 50 supplies the photographed images of the rectangular wires 71 and 72 to the NC device 30. When the camera 50 photographs the rectangular wires 71 and 72, the NC device 30 positions the camera 50 directly above the rectangular wires 71 and 72, and when the rectangular wires 71 and 72 are welded by the superimposed laser beam emitted from the processing head 40, the NC device 30 controls the moving mechanism 60 to position the second storage body 42 directly above the rectangular wires 71 and 72.

[0017] A camera may be placed above the laser processing machine 100, such as on the ceiling of the installation location of the laser processing machine 100, to photograph the rectangular wires 71 and 72. The rectangular wires 71 and 72 may be photographed by both the camera 50 attached to the processing head 40 and a camera placed above the laser processing machine 100.

[0018] 1 shows only one pair of rectangular wires 71 and 72, multiple pairs of rectangular wires 71 and 72 may be arranged, and the laser processing machine 100 may sequentially weld each pair of rectangular wires 71 and 72. This type of welding of rectangular wires 71 and 72 is called hairpin welding.

[0019] The laser processing machine 100 may include a galvanometer scanner 80 for displacing the superimposed laser beam, as shown in FIG. 2 , located between the dichroic mirror 423 and the focusing lens 424 in the second housing 42. The galvanometer scanner 80 includes a first galvanometer mirror 81, a first galvanometer motor 82 for driving the first galvanometer mirror 81, a second galvanometer mirror 83, and a second galvanometer motor 84 for driving the second galvanometer mirror 83. The superimposed laser beam is incident on the first galvanometer mirror 81, reflected therefrom, and then incident on the second galvanometer mirror 83. The superimposed laser beam is reflected by the second galvanometer mirror 83, and then incident on the focusing lens 424.

[0020] The NC device 30 controls the first galvanometer motor 82 and the second galvanometer motor 84 to rotate the first galvanometer mirror 81 and the second galvanometer mirror 83 within a predetermined angle range. By rotating either the first galvanometer mirror 81 or the second galvanometer mirror 83, or both the first galvanometer mirror 81 and the second galvanometer mirror 83, the positions of the superimposed laser beams irradiated onto the rectangular wires 71 and 72 can be moved even when the machining head 40 is stopped.

[0021] In FIG. 1, the shielding gas injection nozzles that spray shielding gas onto the rectangular wires 71 and 72 when welding the rectangular wires 71 and 72, and the shielding gas supply device that supplies shielding gas to the shielding gas injection nozzles are not shown.

[0022] In the laser processing machine 100 shown in FIG. 1, a blue laser oscillator 10 is provided and a blue laser beam L10 is used to weld the rectangular wires 71 and 72. However, the rectangular wires 71 and 72 may be welded using only the infrared laser beam L20 emitted from the infrared laser oscillator 20. The laser beam used to weld the rectangular wires 71 and 72 is not limited to a superimposed laser beam, but may also be an infrared laser beam L20. The rectangular wires 71 and 72 are made of copper, and the light absorption rate of the blue laser beam L10 when irradiated with copper is higher than that of the infrared laser beam L20. Therefore, using a superimposed laser beam can improve the workability when welding the rectangular wires 71 and 72. Furthermore, the rectangular wires 71 and 72 may be welded using only the blue laser beam L10. The laser beams described below refer to the superimposed laser beam, the infrared laser beam L20, or the blue laser beam L10.

[0023] Next, based on the results of the inventor's investigation, we will explain how to irradiate the flat wires 71 and 72 with a laser beam to weld them together without welding defects. Figure 3 shows the state in which the flat wires 71 and 72 are in contact with each other. The opposing sides of the flat wires 71 and 72 at the tip surfaces of the adjacent flat wires 71 and 72 are designated as side S1 (first side) and side S2 (second side), respectively. The side opposite side S1 of the flat wire 71 is designated as side S3 (third side), and the side opposite side S2 of the flat wire 72 is designated as side S4. In Figure 3, the dimension X, which is the length of sides S1 to S4, is, for example, 2.7 mm, and the dimension Y, which is the length connecting sides S5 and S6 perpendicular to sides S1 to S4 of the flat wires 71 and 72, is, for example, 4.7 mm.

[0024] Figure 4 shows a state in which the rectangular wires 71 and 72 are separated by a gap G. Before welding the rectangular wires 71 and 72, the enamel coating previously applied to the tips of the rectangular wires 71 and 72 is removed. As a result, a gap may occur between the tips of the rectangular wires 71 and 72. In Figure 4, the distance between sides S3 and S4 is dimension Y + G. As shown in Figure 3, the sides S1 and S2 of adjacent rectangular wires 71 and 72 may be in contact, resulting in a gap G of 0 mm. Alternatively, as shown in Figure 4, a gap G exceeding 0 mm may exist between sides S1 and S2. The gap G may be up to approximately 1 mm.

[0025] 5 shows a first comparative example, in which a beam spot Bs of a laser beam is positioned between sides S1 and S2 and fixed-point irradiation is performed without moving the beam spot Bs. The position where the laser beam is irradiated is the center of sides S1 and S2. FIGS. 5 to 8 show an example in which the gap amount G is 0 mm.

[0026] Figure 6 shows a second comparative example, in which the processing head 40 is stopped before the beam spot Bs is irradiated onto the side S3, and the beam spot Bs is positioned on the side S3, and the beam spot Bs is moved by a processing distance L0 until it reaches the middle portion of the tip surface of the rectangular wire 72. The middle portion is the area on the tip surface of the rectangular wire 72 that is closer to the side S4 than the side S2 and closer to the side S2 than the side S4. In Figure 6, the NC device 30 moves the processing head 40 to move the beam spot Bs to the middle portion of the tip surface of the rectangular wire 72, and then stops the processing head 40. The position where the laser beam irradiation begins is the center of the side S3.

[0027] Figure 7 shows a third comparative example, in which the NC device 30 moves the machining head 40, which is stopped at a position away from side S3, toward side S3, starts irradiating the laser beam so that the beam spot Bs is located on side S3, and moves the beam spot Bs a machining distance L0 until it reaches the middle of the tip surface of the rectangular wire 72. The position where laser beam irradiation starts is the center of side S3. The dashed arrow indicates that the machining head 40 is moving without irradiating the laser beam. In Figure 7, the NC device 30 moves the machining head 40 so that the beam spot Bs moves to the middle of the tip surface of the rectangular wire 72, then stops irradiating the laser beam and gradually slows down the moving speed of the machining head 40 until it stops.

[0028] 8 shows one or more embodiments of the laser welding method for flat wire when the gap amount G is 0 mm. Fig. 8 shows the state in which the processing head 40 is stopped before irradiating the beam spot Bs onto the side S3, and then the laser beam irradiation is started to position the beam spot Bs on the side S3, and the beam spot Bs is moved by a processing distance L0 to the middle part of the tip surface of the flat wire 72. The position where the laser beam irradiation starts is the center of the side S3.

[0029] 8, the NC device 30 controls the blue laser oscillator 10 and the infrared laser oscillator 20 to emit light, and at the same time controls the moving mechanism 60 to move the laser beam along a moving direction perpendicular to the sides S1 and S3. The NC device 30 moves the processing head 40 to move the beam spot Bs to the middle of the tip surface of the rectangular wire 72, then stops irradiating the laser beam, and gradually slows down the moving speed of the processing head 40 until it stops. The center C(0,0) of the dimension Y when the gap amount G is 0 mm and the center C(0,0) of the dimension Y+G when the gap amount G described below exceeds 0 mm are referred to as reference positions.

[0030] In the fixed-point irradiation shown in Fig. 5, as shown in Fig. 9A, the corners 71e and 72e of the rectangular wires 71 and 72 tend to remain, and the molten zone 73 formed by the melting of the tips of the rectangular wires 71 and 72 is small. The state in which at least one corner 71e of the rectangular wire 71 remains, or at least one corner 72e of the rectangular wire 72 remains, is referred to as edge residue. If the fixed-point irradiation with the laser beam is performed for a long time to prevent edge residue from occurring, as shown in Fig. 9B, the molten zone 73 will expand excessively, and the molten width Mw will become too wide, resulting in poor welding.

[0031] In the irradiation method shown in Fig. 6, as shown in Fig. 9C, welding defects in which the molten portion 73 is biased toward the side where the laser beam irradiation starts or ends tend to occur. If the molten portion 73 is biased to one side, edge residues tend to occur. In the irradiation method shown in Fig. 7, welding defects in which the molten portion 73 is biased tend not to occur, but because the laser beam irradiation starts on side S3 while the processing head 40 is moving, edge residues may occur on the side where the laser beam irradiation starts.

[0032] In the irradiation method shown in Fig. 8, edge residue as shown in Fig. 9A hardly occurs, the fusion width Mw of the fusion zone 73 as shown in Fig. 9B does not become too wide, and the unevenness (uneven melting) of the fusion zone 73 as shown in Fig. 9C hardly occurs. Thus, verification by the present inventors has confirmed that the irradiation method shown in Fig. 8 makes it difficult for the welding defects shown in Figs. 9A to 9C to occur.

[0033] The processing distance L0 in Figure 8 is defined as the reference processing distance L0. When the gap amount G is 0 mm, the center of the edge S3 on the tip surface of the rectangular wire 71 is defined as the irradiation start position where the laser beam irradiation begins. Of the reference processing distance L0, the processing distance from the laser beam irradiation start position to the center C (0,0) is L01, and the processing distance from the center C (0,0) to the laser beam irradiation stop is L02. The laser beam movement speed, i.e., the welding speed of the rectangular wires 71 and 72, is defined as the reference welding speed V0. As shown in Figure 8, when the stopped processing head 40 starts moving, the processing head 40 immediately reaches the reference welding speed V0 and moves at the reference welding speed V0 until the laser beam irradiation is stopped. The welding method in which the irradiation start position is on the edge S3 of the rectangular wire 71 and the rectangular wires 71 and 72 are welded at the reference processing distance L0 and the reference welding speed V0 is referred to as the reference welding method.

[0034] Further verification by the inventors has revealed that some conditions in the standard welding method may need to be changed depending on whether the sides S1 and S2 of the rectangular wires 71 and 72 are in contact and the gap G is 0 mm, as shown in FIG. 3 , or whether the gap G exceeds 0 mm, as shown in FIG. 4 . The NC device 30 measures the gap G between the sides S1 and S3 based on images of the rectangular wires 71 and 72 captured by the camera 50. The NC device 30 and the camera 50 are examples of sensors that measure the gap G between the sides S1 and S3. Other sensors, such as a profile sensor, may be used to measure the gap G. The method for measuring the gap G is not limited.

[0035] If the gap G is 0 mm, the standard welding method is used as described above. If the gap G is within a first range R1 up to a first gap greater than 0 mm, the laser beam irradiation start position should be offset from the center of the edge S3 of the distal end surface of the rectangular wire 71 by half the gap G toward the rectangular wire 72, as shown in Figure 10. G / 2 is referred to as the first offset.

[0036] In the first range R1, the position offset by the first offset amount G / 2 from the center of the side S3 on the tip surface of the rectangular wire 71 is set as the irradiation start position where irradiation of the laser beam begins, and the processing distance L is set as the reference processing distance L0. The processing distance from the laser beam irradiation start position to the center C(0,0) is L01, and the processing distance from the center C(0,0) to the end of irradiation of the laser beam is L02. In the first range R1, the welding speed of the rectangular wires 71 and 72 is set as the reference welding speed V0, which is the same as when the gap amount G is 0 mm.

[0037] If the gap G is within a second range R2, which is between the first gap G and the second gap G, the laser beam irradiation start position can be set at a position offset toward the rectangular wire 72 by a predetermined offset Os in addition to the first offset G / 2, as shown in Figure 11. The offset Os will be referred to as the second offset.

[0038] In the second range R2, the position offset from the center of side S3 on the tip surface of the rectangular wire 71 by the sum of the first offset amount G / 2 and the second offset amount is set as the irradiation start position where irradiation of the laser beam begins, and the processing distance L is set as the reference processing distance L0. The processing distance from the laser beam irradiation start position to the center C(0,0) is L01', which is shorter than L01, and the processing distance from the center C(0,0) to the end of irradiation of the laser beam is L02', which is longer than L02. In the second range R2, the welding speed of the rectangular wires 71 and 72 is set to the reference welding speed V0, which is the same as when the gap amount G is 0 mm.

[0039] If the gap amount is in the third range R3 exceeding the second gap amount, the irradiation start position for starting irradiation of the laser beam should be a position offset by the first offset amount G / 2 from the center of the side S3 on the tip surface of the rectangular wire 71. Also, if the gap amount is in the third range R3, it is preferable to set the processing distance L longer than the reference processing distance L0 and the welding speed faster than the reference welding speed V0.

[0040] FIG. 12 shows detailed welding conditions and welding results when the gap amount G is 0 mm and in the first, second, and third ranges R1, R2, and R3. In FIG. 12, the ranges surrounded by thick solid lines indicate welding conditions that differ from the welding conditions in the standard welding method. In the first range R1, the gap amount G is greater than 0 mm and equal to or less than 0.1 mm. In the second range R2, the gap amount G is greater than 0.1 mm and equal to or less than 0.6 mm. In the third range R3, the gap amount G is greater than 0.6 mm and equal to or less than 1.0 mm. In the example shown in FIG. 12, the gap amount G of 0.1 mm is the first gap amount, and the gap amount G of 0.6 mm is the second gap amount. In FIG. 12, only two gap amounts G, 0.8 mm and 1.0 mm, are shown as examples of the gap amount G in the third range R3.

[0041] The processing distance L is 0.8Y, which is the reference processing distance L0. The welding speed is 2 m / min, which is the reference welding speed V0. The welding conditions other than those shown in Figure 12 are that the laser output of the blue laser oscillator 10 is 1800 W, the laser output of the infrared laser oscillator 20 is 1250 W, and the shielding gas is nitrogen, which is 50 L / min.

[0042] When the gap amount G is 0 mm, the NC device 30 controls the laser processing machine 100 to set the first offset amount to 0 mm and the second offset amount to 0 mm, i.e., to start the laser beam irradiation on the edge S3 of the rectangular wire 71, and to weld the rectangular wires 71 and 72 at the reference welding speed V0 for the reference processing distance L0. As a result, when the gap amount G is 0 mm, no edge residue occurs, the fusion width Mw is not widened to 2.97 mm, and no fusion bias occurs. The laser beam irradiation time is 0.118 s.

[0043] In the first range R1, the NC device 30 sets the first offset amount to G / 2 and the second offset amount to 0 mm, i.e., the laser beam irradiation start position is a position offset by a distance of G / 2 from the side S3 of the rectangular wire 71. Furthermore, in the first range R1, the NC device 30 controls the laser processing machine 100 to weld the rectangular wires 71 and 72 at a reference welding speed V0 and a reference processing distance L0. If the gap amount G is 0.1 mm, the first offset amount is 0.05 mm. As a result, when the gap amount G is greater than 0 mm but less than 0.1 mm, no edge residue occurs, the fusion width Mw is not significantly wider at 3.03 mm, and fusion bias does not occur. The laser beam irradiation time is 0.118 s.

[0044] In the second range R2, the NC device 30 sets the first offset amount to G / 2, and if the gap amount G is 0.2 mm, the second offset amount to 0.2 mm. If the gap amount G is 0.3 to 0.6 mm, the second offset amount to 0.3 mm. In the second range R2, the NC device 30 sets the laser beam irradiation start position to a position offset from the side S3 of the rectangular wire 71 by the sum of the first offset amount and the second offset amount, and controls the laser processing machine 100 to weld the rectangular wires 71 and 72 for a standard processing distance L0 at a standard welding speed V0. As a result, no edge residue occurs in the second range R2, and the fusion width Mw is not significantly widened (3.06 mm, 3.19 mm, 3.14 mm, and 3.15 mm, respectively) when the gap amount G is 0.2 mm to 0.6 mm, so that fusion bias does not occur.

[0045] In the third range R3, the NC device 30 sets the first offset amount to G / 2 and the second offset amount to 0 mm, i.e., the laser beam irradiation start position is a position offset by a distance of G / 2 from the side S3 of the rectangular wire 71. Furthermore, in the third range R3, the NC device 30 controls the laser processing machine 100 to weld the rectangular wires 71 and 72 at a welding speed faster than the reference welding speed V0 over a processing distance L longer than the reference processing distance L0. In the example shown in Figure 12, if the gap amount G is 0.8 mm, the processing distance L is 0.95 Y and the welding speed is 2.2 m / min. If the gap amount G is 1.0 mm, the processing distance L is 1.0 Y and the welding speed is 2.2 m / min.

[0046] As a result, in the third range R3, no edge residue occurs, the melt width Mw is not significantly widened (3.16 mm when the gap amount G is 0.8 mm, and 3.10 mm when the gap amount G is 1.0 mm), and no uneven melting occurs. The laser beam irradiation time is 0.128 s when the gap amount G is 0.8 mm, and 0.134 s when the gap amount G is 1.0 mm.

[0047] In the second range R2 where the gap amount G is wider than the first range R1, let us suppose that the laser beam is irradiated onto the rectangular wires 71 and 72 from a position offset by a first offset amount G / 2 from the side S3 of the rectangular wire 71 as the laser beam irradiation start position. In this case, edge residue tends to occur on the end side of the laser beam irradiation. Therefore, by setting the irradiation start position for the laser beam irradiation to a position offset by a distance obtained by adding a second offset amount exceeding 0 mm to the first offset amount, edge residue can be prevented from occurring on the end side of the laser beam irradiation.

[0048] In the third range R3 where the gap amount G is wider than the second range R2, let us assume that the flat wires 71 and 72 are irradiated with a laser beam from a position offset by a distance obtained by adding a second offset amount exceeding 0 mm to the first offset amount. To prevent edge residue from occurring at the end of the laser beam irradiation, the second offset amount must be set to a distance longer than that in the second range R2. This makes it more likely that edge residue will occur at the start of the laser beam irradiation.

[0049] Therefore, in the third range R3, the first offset amount is set to G / 2, the second offset amount is set to 0 mm, i.e., the laser beam irradiation start position is set to a position offset by a distance of G / 2 from the side S3 of the rectangular wire 71, and the processing distance L is set to be longer than the standard processing distance L0. If the welding speed remains at the standard welding speed V0 even though the processing distance L is set to be longer than the standard processing distance L0, the heat input to the rectangular wires 71 and 72 will increase, and the fusion width Mw may become too wide. Therefore, in the third range R3, the welding speed is set to be faster than the standard welding speed V0.

[0050] In this way, the laser processing machine 100 measures the gap amount G between the sides S1 and S3 and classifies the gap amount G into 0 mm, a first range R1, a second range R2, and a third range R3. If the gap amount G is 0 mm, the laser processing machine 100 controls the laser processing machine 100 to set the laser beam irradiation start position on the side S3 of the rectangular wire 71 and weld the rectangular wires 71 and 72 using a standard welding method with a standard processing distance L0 and a standard welding speed V0. In the first range R1, the laser processing machine 100 offsets the irradiation start position by a first offset amount and controls the laser processing machine 100 to weld the rectangular wires 71 and 72 over the standard processing distance L0 at the standard processing distance L0 and the standard welding speed V0.

[0051] In the second range R2, the laser processing machine 100 offsets the irradiation start position by the first offset amount and the second offset amount, and controls the laser processing machine 100 so that the flat wires 71 and 72 are welded over the reference processing distance L0 at the reference welding speed V0. In the third range R3, the laser processing machine 100 offsets the irradiation start position by the first offset amount, and controls the laser processing machine 100 so that the processing distance L is longer than the reference processing distance L0 and the welding speed is faster than the reference welding speed V0, and welds the flat wires 71 and 72.

[0052] The first gap amount of 0.1 mm, the second gap amount of 0.6 mm, the reference processing distance L0 of 0.8Y, the reference welding speed V0 of 2 m / min, the first range R1, the second range R2, and the third range R3 shown in Figure 12 are merely examples. The welding conditions under which no welding defects occur vary depending on whether the laser processing machine 100 is equipped with both the blue laser oscillator 10 and the infrared laser oscillator 20, or whether it is equipped with only the infrared laser oscillator 20, or whether it is equipped with only the blue laser oscillator 10.

[0053] When the laser processing machine 100 is equipped with both the blue laser oscillator 10 and the infrared laser oscillator 20, the welding conditions under which no welding defects occur differ depending on the laser output of the blue laser oscillator 10, the laser output of the infrared laser oscillator 20, and the shielding gas conditions. When the laser processing machine 100 is equipped with only the infrared laser oscillator 20, the welding conditions under which no welding defects occur differ depending on the laser output of the infrared laser oscillator 20 and the shielding gas conditions. When the laser processing machine 100 is equipped with only the blue laser oscillator 10, the welding conditions under which no welding defects occur differ depending on the laser output of the blue laser oscillator 10 and the shielding gas conditions. Furthermore, in either case, the welding conditions under which no welding defects occur also differ depending on the beam diameter of the laser beam.

[0054] Depending on these various conditions, the range of gap amount G from 0 mm to an upper limit value of, for example, 1.0 mm may be divided into a first range R1 when gap amount G is 0 mm and a first range R2, a second range R2, and a third range R3 when gap amount G exceeds 0 mm so as to prevent welding defects. Depending on various conditions, the reference machining distance L0, the reference welding speed V0, the second offset amount in the second range R2, and the degree of extension of machining distance L and the degree of increase in welding speed in the third range R3 may be set so as to prevent welding defects.

[0055] 12 , the gap amount G of 0.1 mm in the first range R1 may be one of multiple gap amounts G included in the first range R1, or may be the only gap amount G included in the first range R1. In the example shown in Fig. 12 , in the second range R2, the second offset amount is 0.2 mm only when the gap amount G is 0.2 mm, and the second offset amount is 0.3 mm for other gap amounts G. The second offset amount may be a uniform value for all gap amounts G in the second range R2, or may be three or more values.

[0056] The operation of the laser processing machine 100 and the laser welding method executed by the laser processing machine 100 will be described using the flowchart shown in Figure 13. In Figure 13, when the laser processing machine 100 starts operating and the NC device 30 starts processing, the NC device 30 measures the gap amount G between the pair of rectangular wires 71 and 72 in step S11. In step S12, the NC device 30 determines whether the gap amount G is 0 mm. If the gap amount G is 0 mm (YES), in step S13, the NC device 30 sets the first and second offset amounts to 0, the processing distance L to the reference processing distance L0, and the welding speed to the reference welding speed V0, and proceeds to step S19.

[0057] If the gap amount G is not 0 mm in step S12, the NC device 30 determines in step S14 whether the gap amount G is equal to or less than the first gap amount. If the gap amount G is equal to or less than the first gap amount (YES), the NC device 30 sets the first offset amount to G / 2, the second offset amount to 0, the machining distance L to the reference machining distance L0, and the welding speed to the reference welding speed V0 in step S15, and then proceeds to step S19.

[0058] If the gap amount G is not equal to or less than the first gap amount in step S14 (NO), the NC device 30 determines whether the gap amount G is equal to or less than the second gap amount in step S16. If the gap amount G is equal to or less than the second gap amount (YES), the NC device 30 sets the first offset amount to G / 2 and the second offset amount to a predetermined value for each gap amount G in step S17, sets the processing distance L to a reference distance L0, and sets the welding speed to a reference welding speed V0, and proceeds to step S19.

[0059] If the gap amount G is not equal to or less than the second gap amount in step S16 (NO), then in step S18 the NC device 30 sets the first offset amount to G / 2 and the second offset amount to 0. Also, in step S18, the NC device 30 sets the processing distance L for each gap amount G to a distance longer than the reference distance L0, sets the welding speed to a speed higher than the reference welding speed V0, and proceeds to step S19.

[0060] In step S19, the NC device 30 controls the laser processing machine 100 to weld the pair of rectangular wires 71 and 72 using the set offset amount (including 0 mm), processing distance L, and welding speed, and then proceeds to step S20. In step S20, the NC device 30 determines whether there is a next pair of rectangular wires 71 and 72. If there is a next pair of rectangular wires 71 and 72 (YES), the NC device 30 repeats the processing from step S11 onwards. If there is not a next pair of rectangular wires 71 and 72 (NO), the NC device 30 ends the processing.

[0061] 8 shows an example in which the laser beam irradiated onto the rectangular wires 71 and 72 is moved by moving the processing head 40 using the moving mechanism 60. The NC device 30 may stop the processing head 40 and move the laser beam irradiated onto the rectangular wires 71 and 72 using the galvanometer scanner 80.

[0062] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

[0063] This application claims priority based on Japanese Patent Application No. 2023-171073, filed with the Japan Patent Office on October 2, 2023, the entire disclosure of which is incorporated herein by reference.

Claims

1. A method for welding a rectangular wire comprising: a sensor for measuring a gap between a first side of a first rectangular wire and a second side of a second rectangular wire facing each other at the respective tip surfaces of adjacent first and second rectangular wires to be welded; and a control device for controlling the irradiation position of a laser beam irradiated onto the first and second rectangular wires and the movement of the laser beam to weld the first and second rectangular wires, wherein if the gap measured by the sensor is zero, the control device sets the center of a third side opposite to the first side at the tip surface of the first rectangular wire as the irradiation start position of the laser beam, sets the moving speed of the laser beam to a reference welding speed, and moves the laser beam a reference processing distance from the irradiation start position along a moving direction perpendicular to the first and third sides to the middle part at the tip surface of the second rectangular wire to weld the first and second rectangular wires; If the gap amount measured by the sensor exceeds 0 and is within a first range up to a first gap amount, a position offset from the center of the third side toward the second rectangular wire by a first offset amount, which is a distance of 1 / 2 of the gap amount, is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to the reference welding speed, and the laser beam is moved from the irradiation start position by the reference processing distance along a moving direction perpendicular to the first and third sides to weld the first and second rectangular wires, If the gap amount measured by the sensor is within a second range exceeding the first gap amount and up to a second gap amount, a position offset from the center of the third side toward the second rectangular wire by a distance obtained by adding a first offset amount, which is a distance of 1 / 2 of the gap amount, and a predetermined second offset amount exceeding 0 is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to the reference welding speed, and the laser beam is moved from the irradiation start position by the reference processing distance along a moving direction perpendicular to the first and third sides to weld the first and second rectangular wires,If the gap amount measured by the sensor is within a third range exceeding the second gap amount, a position offset from the center of the third side toward the second rectangular wire by a first offset amount, which is 1 / 2 the gap amount, is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to a welding speed faster than the reference welding speed, and the laser beam is moved from the irradiation start position along a moving direction perpendicular to the first and third sides by a processing distance longer than the reference processing distance to weld the first and second rectangular wires.

2. A laser welding machine as claimed in claim 1, further comprising: a laser oscillator which emits the laser beam; a processing head which irradiates the laser beam emitted by the laser oscillator onto the first and second rectangular wires; and a movement mechanism which moves the processing head, wherein the control device controls the laser oscillator to a state in which it does not emit the laser beam, controls the movement mechanism to position and stop the processing head at a position where the processing head irradiates the laser beam to the irradiation start position, and controls the movement mechanism to move the laser beam along the movement direction while controlling the laser oscillator to a state in which it emits the laser beam.

3. A gap amount between a first side of the first rectangular wire and a second side of the second rectangular wire facing each other at each tip surface of the adjacent first and second rectangular wires to be welded is measured by a sensor; if the gap amount measured by the sensor is zero, the center of the third side opposite to the first side at the tip surface of the first rectangular wire is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to a reference welding speed, and the laser beam is moved a reference processing distance from the irradiation start position along a moving direction perpendicular to the first and third sides to the middle part at the tip surface of the second rectangular wire, thereby welding the first and second rectangular wires; If the gap amount measured by the sensor exceeds 0 and is within a first range up to a first gap amount, a position offset from the center of the third side toward the second rectangular wire by a first offset amount, which is a distance of 1 / 2 of the gap amount, is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to the reference welding speed, and the laser beam is moved from the irradiation start position by the reference processing distance along a moving direction perpendicular to the first and third sides to weld the first and second rectangular wires, If the gap amount measured by the sensor is within a second range exceeding the first gap amount and up to a second gap amount, a position offset from the center of the third side toward the second rectangular wire by a distance obtained by adding a first offset amount, which is a distance of 1 / 2 of the gap amount, and a predetermined second offset amount exceeding 0 is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to the reference welding speed, and the laser beam is moved from the irradiation start position by the reference processing distance along a moving direction perpendicular to the first and third sides to weld the first and second rectangular wires,If the gap amount measured by the sensor is within a third range exceeding the second gap amount, a position offset from the center of the third side toward the second rectangular wire by a first offset amount, which is 1 / 2 the gap amount, is set as the irradiation start position of the laser beam, the moving speed of the laser beam is set to a welding speed faster than the reference welding speed, and the laser beam is moved from the irradiation start position along a moving direction perpendicular to the first and third sides by a processing distance longer than the reference processing distance to weld the first and second rectangular wires. This is a laser welding method for rectangular wires.

4. A method for laser welding rectangular wire as described in claim 3, comprising controlling a laser oscillator to a state where it does not emit the laser beam, and positioning and stopping a processing head at a position where the processing head irradiates the laser beam at the irradiation start position, and simultaneously controlling the laser oscillator to a state where it emits the laser beam, starting movement of the processing head to move the laser beam along the movement direction.

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