Laser-welding machine, laser-welding method, and machining program creation method

Abstract

A sensing device senses each pair of flat wires (71L and 71R) in order to acquire a gap amount or a positional deviation amount between the pair of flat wires (71L and 71R). In accordance with the gap amount or the positional deviation amount, a control device selects one irradiation condition from among a plurality of irradiation conditions for irradiating the tip surfaces of each pair of flat wires (71L and 71R) with a laser beam. The control device creates a machining program for welding the plurality of pairs of flat wires (71L and 71R) under irradiation conditions selected for the respective pairs of flat wires (71L and 71R). The control device controls a laser oscillator and a displacement mechanism so as to weld the respective pairs of flat wires (71L and 71R) in accordance with the created machining program.

Description

Laser welding machine, laser welding method, and machining program creation method

[0001] The present disclosure relates to a laser welding machine, a laser welding method, and a machining program creation method.

[0002] In a motor used in an electric vehicle or a hybrid vehicle, both ends of segment coils adjacent to each other in the radial direction of a plurality of U-shaped segment coils mounted on a core are welded by a laser welding machine (see Patent Document 1). Both ends of the segment coils adjacent to each other in the radial direction are a pair of straight lines. Welding both ends of the segment coils adjacent to each other in the radial direction is called hairpin welding.

[0003] European Patent Application Publication No. 3088124

[0004] The number of hairpins for forming one motor is several tens to several hundreds. There may be a gap between a pair of straight lines constituting one hairpin, and the amount of the gap is not constant. The pair of straight lines may be displaced in the direction along the opposite sides of the pair of straight lines, and the amount of displacement is not constant. When irradiating each hairpin of a plurality of hairpins having a plurality of gap amounts or a plurality of displacement amounts with a laser beam for welding, it is common to weld each hairpin under irradiation conditions corresponding to the hairpin having the largest gap amount or displacement amount.

[0005] However, when welding each hairpin under irradiation conditions corresponding to the hairpin having the largest gap amount or displacement amount, excessive heat input may occur to the hairpin having a small gap amount or displacement amount, causing the straight line to melt and fall off, or the coating for insulation to burn out, resulting in poor welding. In addition, since the irradiation time of the laser beam increases by applying the amount of heat input corresponding to the hairpin having the largest gap amount or displacement amount to all the hairpins, the tact time for welding one motor becomes long. There is a demand for the emergence of a laser welding machine, a laser welding method, and a machining program creation method that can reduce the occurrence of poor welding and shorten the tact time even when the gap amount or displacement amount of a pair of straight lines varies.

[0006] A first aspect of one or more embodiments includes a laser oscillator that emits a laser beam, a processing head that irradiates the laser beam emitted from the laser oscillator onto the tip surfaces of each pair of rectangular wires in a plurality of pairs of rectangular wires to weld each pair of rectangular wires, a displacement mechanism that displaces the laser beam irradiating each pair of rectangular wires, a sensing device that senses each pair of rectangular wires in order to obtain at least one of the gap between each pair of rectangular wires and the displacement between each pair of rectangular wires in a direction along the opposing sides of the tip surfaces of each pair of rectangular wires, and the sensing device The present invention provides a laser welding machine comprising: a device that senses each pair of rectangular wires and, in accordance with at least one of the gap amount between each pair of rectangular wires and the positional displacement amount between each pair of rectangular wires obtained as a result of sensing each pair of rectangular wires, selects one of a plurality of irradiation conditions for irradiating the tip surface of each pair of rectangular wires with the laser beam in order to weld each pair of rectangular wires; creates a processing program for welding the plurality of pairs of rectangular wires with the selected irradiation condition for each pair of rectangular wires; and a control device that controls the laser oscillator and the displacement mechanism to weld the plurality of pairs of rectangular wires according to the created processing program.

[0007] A second aspect of one or more embodiments provides a laser welding method in which a sensing device senses each pair of flat wires in a plurality of pairs of flat wires to be welded, obtains at least one of the gap amount between each pair of flat wires and the displacement amount between each pair of flat wires in the direction along the opposing sides of the tip faces of each pair of flat wires, selects one of a plurality of irradiation conditions for irradiating the tip faces of each pair of flat wires with a laser beam to weld each pair of flat wires in correspondence with at least one of the gap amount and the displacement amount, and welds the plurality of pairs of flat wires with the irradiation condition selected for each pair of flat wires in the plurality of pairs of flat wires.

[0008] A third aspect of one or more embodiments provides a method for creating a processing program that uses a sensing device to sense each pair of flat wires in a plurality of pairs of flat wires to be welded, to obtain at least one of the gap amount between each pair of flat wires and the displacement amount between each pair of flat wires in the direction along the opposing sides of the tip faces of each pair of flat wires, to select one of a plurality of irradiation conditions for irradiating the tip faces of each pair of flat wires with a laser beam in accordance with at least one of the gap amount and the displacement amount, and to create a processing program that welds the plurality of pairs of flat wires with the irradiation condition selected for each pair of flat wires in the plurality of pairs of flat wires.

[0009] According to one or more embodiments of the laser welding machine, laser welding method, and processing program creation method, even if there is variation in the gap or misalignment of a pair of rectangular wires, the occurrence of welding defects can be reduced and the cycle time can be shortened.

[0010] Figure 1 is a diagram showing an example configuration of a laser welding machine according to one or more embodiments. Figure 2 is a plan view showing the gap and displacement between a pair of rectangular wires. Figure 3 is a side view showing the height displacement between a pair of rectangular wires. Figure 4 is a perspective view showing a galvanometer scanner that may be included in a laser welding machine according to one or more embodiments. Figure 5 is a sequence diagram showing a welding method for multiple pairs of rectangular wires performed by a laser welding machine according to one or more embodiments. Figure 6A is a partial plan view showing an example in which a region including three pairs of rectangular wires on a rotating body is defined as an irradiation area in which a displacement mechanism displaces the laser beam to irradiate each pair of rectangular wires with the laser beam. Figure 6B is a partial plan view showing an example in which a region including nine pairs of rectangular wires on a rotating body is defined as an irradiation area in which a displacement mechanism displaces the laser beam to irradiate each pair of rectangular wires with the laser beam. Figure 7 is a diagram showing an example of a condition table referenced by an NC device included in a laser welding machine according to one or more embodiments. Figure 8 is a side view showing the first step of a first irradiation pattern used in a laser welding method according to one or more embodiments. Figure 9 is a side view showing the second step of the first irradiation pattern. Figure 10 is a side view showing the third step of the first irradiation pattern. Figure 11 is a plan view showing the first step of the first irradiation pattern. Figure 12 is a plan view showing the second step of the first irradiation pattern. Figure 13 is a plan view showing the third step of the first irradiation pattern. Figure 14 is a side view showing the first step of the second irradiation pattern used in a laser welding method according to one or more embodiments. Figure 15 is a side view showing the second step of the second irradiation pattern. Figure 16 is a side view showing the third step of the second irradiation pattern. Figure 17 is a side view showing the fourth step of the second irradiation pattern. Figure 18 is a plan view showing the first step of the second irradiation pattern. Figure 19 is a plan view showing the second step of the second irradiation pattern. Figure 20 is a plan view showing the third step of the second irradiation pattern. Figure 21 is a plan view showing the fourth step of the second irradiation pattern. Figure 22 is a plan view showing the first step of the third irradiation pattern. Figure 23 is a plan view showing the second step of the third irradiation pattern. Figure 24 is a plan view showing the third step of the third irradiation pattern.Figure 25 is a plan view showing the fourth step of the third irradiation pattern. Figure 26 is a waveform diagram showing that a monitoring device that may be included in one or more embodiments of a laser welding machine determines the quality of the weld using different thresholds depending on the position of a pair of flat wires within the irradiation area of ​​the laser beam. Figure 27 is a waveform diagram showing that a monitoring device that may be included in one or more embodiments of a laser welding machine determines the quality of the weld by varying the gain multiplied by the light intensity count value depending on the position of a pair of flat wires within the irradiation area of ​​the laser beam. Figure 28 is a conceptual diagram showing the region on a rotating body where nine pairs of flat wires are arranged. Figure 29 is a partial plan view showing an example where, upon completion of welding of multiple pairs of flat wires, there is a pair of flat wires that remain unwelded. Figure 30 is a partial perspective view showing a pair of flat wires with a molten ball of appropriate size formed at their tips. Figure 31 is a diagram showing an example of the integral value of the light intensity count value and time at which a molten ball of appropriate size is formed, depending on the position of a pair of flat wires within the irradiation area of ​​the laser beam. Figure 32 shows an example of how an NC device controls the irradiation time of a laser beam irradiated onto a pair of flat wires, depending on whether the integral value for forming a molten ball of a suitable size is reached in a shorter time than the standard time, or whether the integral value for forming a molten ball of a suitable size is reached in a longer time than the standard time.

[0011] Hereinafter, a laser welding machine, a laser welding method, and a processing program creation method according to one or more embodiments will be described with reference to the attached drawings. First, using Figure 1, a laser welding machine 100 according to one or more embodiments that welds each pair of flat wires (hairpins) in a plurality of pairs of flat wires will be described. The laser welding machine 100 shown in Figure 1 executes a laser welding method according to one or more embodiments. The NC (Numerical Control) device 10 equipped in the laser welding machine 100 executes a processing program creation method according to one or more embodiments to create a processing program, and controls the laser welding machine 100 to weld each pair of flat wires according to the created processing program.

[0012] As shown in Figure 1, the laser welding machine 100 includes an NC device 10, a blue laser oscillator 20, a transmission fiber 22, a collimating lens 30, semi-transparent mirrors 31 and 32, a mirror 33, an internal camera 34, a light receiving unit 35, a processing head 40, a sensing camera 54, and a monitoring device 55. The NC device 10 has a storage unit 11 that stores a condition table, which will be described later. The storage unit 11 can be made of non-volatile memory or ROM, and may be configured to be rewritable. The NC device 10 is an example of a control device that controls each part of the laser welding machine 100. The processing head 40 has a galvanometer scanner 42 and a focusing lens 43.

[0013] The processing head 40 is configured to be movable by a moving mechanism (not shown). The processing head 40 may irradiate the laser beam while its position is fixed, without moving it by the moving mechanism. The processing head 40 may irradiate the laser beam while its position is moved by the moving mechanism.

[0014] The blue laser oscillator 20 emits a blue laser beam with a wavelength of 400 nm to 460 nm. The transmission fiber 22 transmits the laser beam emitted from the blue laser oscillator 20 and emits a divergent laser beam from the exit end, as shown by the dashed line. Instead of the blue laser oscillator 20, an infrared laser oscillator that emits an infrared laser beam with a wavelength of 1060 nm to 1090 nm may be used. It is preferable to use a fiber laser oscillator as the infrared laser oscillator. The laser welding machine 100 may be equipped with both a blue laser oscillator 20 and an infrared laser oscillator, and the transmission fiber 22 may transmit a superimposed laser beam in which the blue laser beam and the infrared laser beam are superimposed on each other.

[0015] The semi-transparent mirrors 31 and 32 and the mirror 33 can be made of dichroic mirrors. It is not essential for the laser welding machine 100 to be equipped with a monitoring device 55, but it is preferable. If the laser welding machine 100 is not equipped with a monitoring device 55, the mirror 33 and the light receiving unit 35 are unnecessary, and a mirror can be used instead of the semi-transparent mirror 32. The collimating lens 30 and the semi-transparent mirror 31 may be located within the processing head 40.

[0016] The collimating lens 30 converts the divergent laser beam emitted from the exit end of the transmission fiber 22 into collimated light. The collimated laser beam is reflected by the semi-transparent mirror 31 and heads towards the galvanoscanner 42 in the processing head 40, which will be described later. The collimated laser beam passes through the galvanoscanner 42 and enters the focusing lens 43. The focusing lens 43 focuses the collimated laser beam, and the focused laser beam irradiates the pair of flat wires 71L and 71R to be welded. The laser beam emitted from the focusing lens 43 and irradiated onto the pair of flat wires 71L and 71R will be referred to as the laser beam LB.

[0017] Below the processing head 40 is a rotating body 110 on which multiple pairs of coated copper wires 61L and 61R are mounted. The ends of the coated copper wires 61L and 61R are flat rectangular wires 71L and 71R from which the coating has been removed. Typically, the coating is enamel coating. The multiple pairs of coated copper wires 61L and 61R are mounted on the rotating body 110 such that the entire flat rectangular wires 71L and 71R protrude from the upper surface of the rotating body 110. In detail, the rotating body 110 consists of a table that can rotate by a rotating mechanism (not shown) and a motor positioned on the table. The multiple pairs of coated copper wires 61L and 61R protrude from the upper surface of the motor's stator core. As the table rotates, the motor on which the multiple pairs of coated copper wires 61L and 61R are mounted rotates.

[0018] Typically, the rotating body 110 is circular, and multiple pairs of rectangular wires 71L and 71R are arranged circumferentially. For example, multiple pairs of rectangular wires 71L and 71R are arranged circumferentially at three radial positions on the rotating body 110. The NC device 10 rotates the rotating body 110 sequentially to weld all pairs of rectangular wires 71L and 71R arranged on the rotating body 110. Although the processing head 40 is fixed in position, the rotating body 110, on which the multiple pairs of rectangular wires 71L and 71R are mounted, rotates. Therefore, the laser welding machine 100 can sequentially weld multiple pairs of rectangular wires 71L and 71R.

[0019] Before the laser welding machine 100 welds multiple pairs of rectangular wires 71L and 71R, the sensing camera 54 photographs each pair of rectangular wires 71L and 71R. The NC device 10 rotates the rotating body 110 by predetermined angles so that the sensing camera 54 photographs the multiple pairs of rectangular wires 71L and 71R arranged in the circumferential direction by predetermined angles. The sensing camera 54 supplies the images of the multiple pairs of rectangular wires 71L and 71R to the NC device 10. Based on the images supplied from the sensing camera 54, the NC device 10 obtains the position of each pair of rectangular wires 71L and 71R.

[0020] Furthermore, the NC device 10 acquires at least one of the gap amount G and the positional displacement amount S between each pair of rectangular wires 71L and 71R, as shown in Figure 2, based on the captured image. The gap amount G is the distance between the opposing sides of the tip faces 71La and 71Ra of each pair of rectangular wires 71L and 71R. The positional displacement amount S is the distance by which the rectangular wires 71L and 71R are shifted in the direction along the opposing sides of the tip faces 71La and 71Ra. It is preferable for the NC device 10 to acquire both the gap amount G and the positional displacement amount S between each pair of rectangular wires 71L and 71R.

[0021] The sensing camera 54 is an example of a sensing device that senses each pair of rectangular wires 71L and 71R in order to acquire at least one of the gap amount G and the positional displacement amount S of each pair of rectangular wires 71L and 71R. When the sensing device is the sensing camera 54, the gap amount G or positional displacement amount S of each pair of rectangular wires 71L and 71R is acquired by the NC device 10 by image analysis of the captured images.

[0022] Each pair of rectangular wires 71L and 71R may be photographed from the side using a sensing camera 54 or other sensing camera. The NC device 10 may acquire the height displacement H of the tip surfaces 71La and 71Ra of each pair of rectangular wires 71L and 71R, as shown in Figure 3. The NC device 10 may also acquire the area of ​​the tip surfaces 71La and 71Ra.

[0023] Instead of the sensing camera 54, a laser scanner can also be used as a sensing device. A laser scanner can acquire the three-dimensional position and shape of an object by irradiating the object with laser light and detecting the reflected light from the object with a detector. Therefore, by using a laser scanner as a sensing device, the gap amount G, positional displacement amount S, height displacement amount H, and the area of ​​the tip surfaces 71La and 71Ra can be acquired. If the sensing camera 54 is used as a sensing device, the gap amount G and positional displacement amount S can be acquired at a low cost.

[0024] Thus, the NC device 10 has previously acquired the positions of the multiple pairs of rectangular wires 71L and 71R arranged on the rotating body 110, as well as the gap amount G or positional displacement amount S between each pair of rectangular wires 71L and 71R. Therefore, the NC device 10 can control the laser welding machine 100 to weld each pair of rectangular wires 71L and 71R while photographing each pair of rectangular wires 71L and 71R with the internal camera 34.

[0025] In Figure 1, visible light reflected by one or more flat wires 71L and 71R and the rotating body 110 passes through the focusing lens 43 and the galvanometer scanner 42, then through the semi-transparent mirror 31, is reflected by the semi-transparent mirror 32, and enters the internal camera 34. The wavelength of the visible light is between 450 nm and 900 nm. The image captured by the internal camera 34 is incident on the NC device 10. Based on the captured image, the NC device 10 detects the position of each pair of flat wires 71L and 71R during welding. The NC device 10 controls the emission of the laser beam by the blue laser oscillator 20 and controls the galvanometer scanner 42 to irradiate each pair of flat wires 71L and 71R with the laser beam LB and weld each pair of flat wires 71L and 71R.

[0026] As shown in Figure 4, the galvanoscanner 42 includes a first galvano mirror 421, a first galvano motor 422 that drives the first galvano mirror 421, a second galvano mirror 423, and a second galvano motor 424 that drives the second galvano mirror 423. The laser beam of collimated light reflected by the semi-transparent mirror 31 is incident on the first galvano mirror 421, reflected, and then incident on the second galvano mirror 423. The laser beam is reflected by the second galvano mirror 423 and then incident on the focusing lens 43.

[0027] The NC device 10 controls the first galvanometer motor 422 and the second galvanometer motor 424 to rotate the first galvanometer mirror 421 and the second galvanometer mirror 423 within a predetermined angular range. By rotating one or both of the first galvanometer mirror 421 and the second galvanometer mirror 423, the NC device 10 can displace or vibrate the laser beam.

[0028] The galvanoscanner 42 displaces the laser beam reflected by the semi-transparent mirror 31 and directs it into the focusing lens 43. The galvanoscanner 42 is an example of a displacement mechanism that displaces the laser beam when irradiating the laser beam LB, focused by the focusing lens 43, onto the flat rectangular wires 71L and 71R. By continuously displacing the laser beam LB, the galvanoscanner 42 can vibrate the laser beam LB in any pattern.

[0029] While it is not essential for the laser welding machine 100 to be equipped with a galvanoscanner 42 as a displacement mechanism, a galvanoscanner 42 is preferred as such. When the laser welding machine 100 is equipped with a galvanoscanner 42, the laser beam can be displaced at high speed during welding of each pair of rectangular wires 71L and 71R. Furthermore, when the laser welding machine 100 is equipped with a galvanoscanner 42, the laser beam can be displaced more precisely compared to a mechanism that displaces the processing head 40 itself.

[0030] Returning to Figure 1, the monitoring device 55 monitors the detected light that has passed through the semi-transparent mirrors 31 and 32 and reflected by the mirror 33. As an example, the light receiving unit 35 and the monitoring device 55 are connected by an optical fiber, and the light receiving unit 35 consists of a focusing lens for focusing the detected light and a coupler for the optical fiber. The detection light received by the light receiving unit 35 is input to the monitoring device 55. The NC device 10 performs controls related to the welding of each pair of flat wires 71L and 71R based on the detected light monitored by the monitoring device 55. As controls related to welding, the NC device 10 may control the monitoring device 55 to determine the quality of the welding of each pair of flat wires 71L and 71R. As controls related to welding, the NC device 10 may control the blue laser oscillator 20 to weld each pair of flat wires 71L and 71R.

[0031] When the blue laser oscillator 20 is used as the laser oscillator, the detection light can be either the visible light or the near-infrared light emitted when each pair of flat wires 71L and 71R are being welded. The wavelength of the near-infrared light is between 1300 nm and 1500 nm. When the infrared laser oscillator is used as the laser oscillator, the detection light can be either the visible light or the near-infrared light emitted when each pair of flat wires 71L and 71R are being welded, or the reflected light of the laser beam LB. In this way, the monitoring device 55 monitors at least one of the reflected light of the laser beam, the emitted visible light, and the emitted near-infrared light when each pair of flat wires 71L and 71R are being welded as the detection light.

[0032] The internal camera 34 receives visible light reflected by the semi-transparent mirror 32. Not all of the visible light incident on the semi-transparent mirror 32 is reflected by it; some passes through the semi-transparent mirror 32 and enters the mirror 33. When visible light is used as detection light, the light receiving unit 35 only needs to receive the small amount of visible light that has passed through the semi-transparent mirror 32 and been reflected by the mirror 33. The monitoring device 55 can determine the quality of the welding based on the small amount of visible light reflected by the mirror 33 that has been received by the light receiving unit 35. When an infrared laser oscillator is used instead of the blue laser oscillator 20, the semi-transparent mirror 31 reflects most of the reflected light of the infrared laser beam LB, some of which passes through the semi-transparent mirror 31 and through the semi-transparent mirror 32 and enters the mirror 33. When the reflected light of an infrared laser beam LB is used as the detection light, the light receiving unit 35 only needs to receive the small amount of reflected light from the laser beam LB that has passed through the semi-transparent mirror 31 and been reflected by the mirror 33. The monitoring device 55 can determine the quality of the welding based on the small amount of reflected light from the laser beam LB that has been reflected by the mirror 33 and received by the light receiving unit 35.

[0033] In Figure 1, the shielding gas injection nozzles that spray shielding gas onto each pair of rectangular wires 71L and 71R during welding, and the shielding gas supply device that supplies shielding gas to the shielding gas injection nozzles are omitted from the illustration.

[0034] The welding method for multiple pairs of flat wires 71L and 71R performed by the laser welding machine 100 will be explained using the sequence diagram shown in Figure 5. In Figure 5, the laser welding machine 100 refers to the components other than the NC device 10. In Figure 5, in step S1, the operator 200 instructs the NC device 10 to start welding, sequentially welding multiple pairs of flat wires 71L and 71R. The operator 200 can start welding by operating the operation buttons on the operation / display unit (not shown) connected to the NC device 10.

[0035] In step S2, the NC device 10 commands the rotation of the rotating body 110. In step S3, the NC device 10 commands the sensing camera 54 to take a picture of the rotating body 110. Steps S2 and S3 may occur simultaneously, or they may be performed in reverse order. In step S4, the sensing camera 54 transmits the image data of the captured image of the rotating body 110 to the NC device 10.

[0036] In step S5, the NC device 10 receives image data and analyzes the image. In step S6, the NC device 10 refers to the irradiation conditions for irradiating each pair of flat wires 71L and 71R with the laser beam LB and the monitoring conditions in the monitoring device 55, which are set in the condition table stored in the storage unit 11. Furthermore, according to the analysis results of the captured image, the NC device 10 selects the irradiation conditions for the laser beam LB and the monitoring conditions for the monitoring device 55 for each pair of flat wires 71L and 71R.

[0037] The irradiation conditions for the laser beam LB may be the irradiation time during which the laser beam LB is irradiated onto a pair of flat wires 71L and 71R. The irradiation time may be the individual irradiation time for flat wire 71L and the irradiation time for flat wire 71R, or it may be the total irradiation time for the pair of flat wires 71L and 71R. The irradiation conditions for the laser beam LB may also be the laser output (laser power) of the blue laser oscillator 20 when the laser beam LB is irradiated onto a pair of flat wires 71L and 71R. The irradiation conditions for the laser beam LB may also be the duty cycle when the blue laser oscillator 20 emits a pulsed laser beam.

[0038] The irradiation conditions for the laser beam LB may be the moving speed at which the laser beam LB is moved to weld a pair of flat wires 71L and 71R. The irradiation conditions for the laser beam LB may also be the setting of the irradiation start position for irradiating the pair of flat wires 71L and 71R with the laser beam LB, or the setting of the irradiation end position. The irradiation conditions for the laser beam LB may also be the setting of both the irradiation start position and the irradiation end position for irradiating the pair of flat wires 71L and 71R with the laser beam LB. The irradiation conditions for the laser beam LB may be any combination of two or more of the following: irradiation time, laser output, duty cycle, moving speed, setting of irradiation start position, and setting of irradiation end position.

[0039] The irradiation conditions for the laser beam LB may be an irradiation pattern in which the laser beam LB is irradiated onto a pair of flat wires 71L and 71R. The irradiation pattern should preferably consist of the number of welding steps for the pair of flat wires 71L and 71R and the trajectory pattern of the laser beam LB irradiated onto the pair of flat wires 71L and 71R in each step.

[0040] The NC device 10 selects irradiation and monitoring conditions corresponding to either the gap amount G or the misalignment amount S between each pair of rectangular wires 71L and 71R. The NC device 10 may select irradiation and monitoring conditions corresponding to a combination of gap amount G and misalignment amount S. The NC device 10 may also select irradiation and monitoring conditions corresponding to a combination of gap amount G, misalignment amount S, and height misalignment amount H. The NC device 10 may also select irradiation and monitoring conditions corresponding to a combination of gap amount G, misalignment amount S, height misalignment amount H, and the areas of the tip surfaces 71La and 71Ra. Details of the monitoring conditions will be described later.

[0041] In step S7, the NC device 10 creates a processing program to weld multiple pairs of flat wires 71L and 71R using laser beam LB irradiation conditions selected for each pair of flat wires 71L and 71R. The NC device 10 stores the processing program and the monitoring conditions for each pair of flat wires 71L and 71R in the storage unit 11. In step S8, the NC device 10 commands the laser welding machine 100 to start welding. The command to start welding here is a command to activate various parts such as the blue laser oscillator 20 in order to weld multiple pairs of flat wires 71L and 71R.

[0042] In step S9, the NC device 10 instructs the monitoring device 55 to set the monitoring conditions for welding each pair of rectangular wires 71L and 71R, which are stored in the storage unit 11. Once the monitoring device 55 has completed setting the monitoring conditions, in step S10 it notifies the NC device 10 that the setting is complete.

[0043] In step S11, the NC device 10 commands the rotation mechanism of the rotating body 110 to rotate the rotating body 110 at predetermined angle intervals. In step S12, the NC device 10 commands the blue laser oscillator 20 and the galvanometer scanner 42 to sequentially irradiate a group of pairs of flat wires 71L and 71R that are the targets to be irradiated with the laser beam LB during the stop period when the rotating body 110 is stopped rotating. The group of pairs of flat wires 71L and 71R may consist of two or more pairs of flat wires 71L and 71R. In this case, the processing head 40 is fixed in position and sequentially irradiates the group of pairs of flat wires 71L and 71R with the laser beam LB while the rotating body 110 is stopped rotating. Alternatively, the processing head 40 may move while sequentially irradiating the group of pairs of flat wires 71L and 71R with the laser beam LB.

[0044] As shown in Fig. 6A, three pairs of straight lines 71L and 71R enclosed by dashed lines and arranged at the same angular positions along the radial direction of the rotating body 110 can be regarded as a group of pairs of straight lines 71L and 71R. The laser welding machine 100 can use the region including the three pairs of straight lines 71L and 71R as an irradiation region where the galvanometer scanner 42 displaces the laser beam and irradiates the laser beam onto each pair of straight lines 71L and 71R. The pair of straight lines 71L and 71R at the central position in the radial direction is defined as the straight line pair 71CTR, the pair of straight lines 71L and 71R at the outer side in the radial direction is defined as the straight line pair 71OS, and the pair of straight lines 71L and 71R at the inner side in the radial direction is defined as the straight line pair 71IS.

[0045] Also, as shown in Fig. 6B, nine pairs of straight lines 71L and 71R enclosed by dashed lines and arranged at three same angular positions along the radial direction of the rotating body 110 can be regarded as a group of pairs of straight lines 71L and 71R. The laser welding machine 100 can use the region including the nine pairs of straight lines 71L and 71R as an irradiation region where the galvanometer scanner 42 displaces the laser beam and irradiates the laser beam onto each pair of straight lines 71L and 71R.

[0046] In Fig. 6A, the center of the focusing lens 43 is located directly above the straight line pair 71CTR. The NC device 10 controls the galvanometer scanner 42 so as to irradiate the laser beam LB onto the straight line pairs 71CTR, 71OS, and 71IS in an arbitrary order and weld the straight line pairs 71CTR, 71OS, and 71IS in sequence. In Fig. 6B, the center of the focusing lens 43 is located directly above the pair of straight lines 71L and 71R at the center among the nine pairs of straight lines 71L and 71R. The NC device 10 controls the galvanometer scanner 42 so as to irradiate the laser beam LB onto each pair of straight lines 71L and 71R among the nine pairs of straight lines 71L and 71R in sequence and weld each pair of straight lines 71L and 71R in sequence.

[0047] In the above example, the processing head 40 irradiates the laser beam LB in sequence on a group of pairs of flat diagonal lines 71L and 71R in a state where the rotating body 110 has stopped rotating. In order to shorten the welding time for all pairs of flat diagonal lines 71L and 71R, the NC device 10 may control each part as follows. In step S12, the NC device 10 commands the blue laser oscillator 20 and the galvanometer scanner 42 to irradiate the laser beam LB in sequence on a pair of flat diagonal lines 71L and 71R to be irradiated while rotating the rotating body 110. In this case, while the rotating body 110 is rotating, the processing head 40 irradiates the laser beam LB in sequence on each pair of flat diagonal lines 71L and 71R.

[0048] The irradiation pattern (trajectory pattern) of the laser beam LB at this time is preferably an irradiation pattern considering the rotation of the rotating body 110. When welding each pair of flat diagonal lines 71L and 71R while rotating the rotating body 110, the NC device 10 preferably controls the table of the rotating body 110 and the galvanometer scanner 42 so that the laser beam LB is irradiated in a desired irradiation pattern.

[0049] Returning to FIG. 5, in step S13, the NC device 10 commands the monitoring device 55 to monitor the welding of each pair of flat diagonal lines 71L and 71R. In step S14, the monitoring device 55 detects the amount of the incident detection light each time a pair of flat diagonal lines 71L and 71R is welded, and in step S15, determines the quality of the welding.

[0050] When the welding of all pairs of flat diagonal lines 71L and 71R is completed, in step S16, the NC device 10 commands the blue laser oscillator 20 to stop the emission of the laser beam in order to stop the irradiation of the laser beam LB on the flat diagonal lines 71L and 71R. In step S17, the monitoring device 55 notifies the NC device 10 of the determination result of the quality of the welding. The NC device 10 may display the determination result on the display unit of the operation / display unit. In step S18, the NC device 10 notifies the operator 200 of the end of the welding.

[0051] Referring to Figures 7 to 25, an example of a condition table stored in the memory unit 11 and how a pair of flat wires 71L and 71R are welded by irradiation with the laser beam LB under each irradiation condition set in the condition table will be specifically explained. The condition table shown in Figure 7 shows an example in which irradiation conditions and monitoring conditions are set in accordance with a combination of gap amount G and positional displacement amount S. The condition table shown in Figure 7 shows an example in which an irradiation pattern is set as the irradiation condition. For each irradiation pattern, one or more of the following may be set: irradiation time, laser output, duty cycle, movement speed, irradiation start position, and irradiation end position.

[0052] The condition table stored in the memory unit 11 may be a condition table in which irradiation conditions and monitoring conditions are set corresponding to the gap amount G. The condition table stored in the memory unit 11 may be a condition table in which irradiation conditions and monitoring conditions are set corresponding to the positional displacement amount S.

[0053] As shown in Figure 7, the gap amount G is divided into three groups: 0 mm or more and less than 0.6 mm, 0.6 mm or more and 1.0 mm or less, and greater than 1.0 mm. The positional displacement amount S is divided into three groups: 0 mm or more and 0.5 mm or less, 0.5 mm or more and 1.0 mm or less, and greater than 1.0 mm. The first irradiation pattern Pt1 and monitoring condition M1 are set for the group where the gap amount G is 0 mm or more and less than 0.6 mm and the positional displacement amount S is 0 mm or more and 0.5 mm or less. The first irradiation pattern Pt1 and monitoring condition M1 are also set for the group where the gap amount G is 0 mm or more and less than 0.6 mm and the positional displacement amount S is 0.5 mm or more and 1.0 mm or less.

[0054] For the group where the gap amount G is 0.6 mm or more and 1.0 mm or less, and the misalignment amount S is 0 mm or more and 0.5 mm or less, the second irradiation pattern Pt2 and monitoring condition M2 are set. For the group where the gap amount G is 0.6 mm or more and 1.0 mm or less, and the misalignment amount S is 0.5 mm or more and 1.0 mm or less, the third irradiation pattern Pt3 and monitoring condition M3 are set. For each group where the gap amount G exceeds 1.0 mm or the misalignment amount S exceeds 1.0 mm, the irradiation pattern is set to "0" and the monitoring condition is set to "0". Irradiation pattern "0" indicates that the pair of flat wires 71L and 71R will not be welded, and monitoring condition "0" indicates that monitoring will not be performed.

[0055] A condition table for setting irradiation conditions and a condition table for setting monitoring conditions may be provided separately. The group for setting the first irradiation pattern Pt1 to the third irradiation pattern Pt3 and the group for setting monitoring conditions M1 to M3 are common, but the former group and the latter group may be different. The group combining the gap amount G and the positional displacement amount S may be divided into smaller groups, and different monitoring conditions may be set for each group.

[0056] The first irradiation pattern Pt1 will be specifically explained using Figures 8 to 13. Figures 8 to 10 are side views showing each step of the first irradiation pattern Pt1, and Figures 11 to 13 are plan views showing each step of the first irradiation pattern Pt1. In Figures 11 to 13 and the plan view described later, Bs indicates the beam spot of the laser beam LB. In Figures 8 to 13, the gap amount G is 0 mm or more and less than 0.6 mm, and the positional displacement amount S is 0 mm.

[0057] Figures 8 and 11 show the first step of the first irradiation pattern Pt1. As shown in Figure 8(a) and Figure 11(a), the laser welding machine 100 irradiates the laser beam LB onto the center of the tip surface 71La of one of a pair of adjacent rectangular wires 71L and 71R to be welded. At this time, the NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to irradiate the laser beam LB onto the center of the tip surface 71La of the rectangular wire 71L.

[0058] As a result, the tip of the rectangular wire 71L melts, and a first molten portion 72L is formed on the rectangular wire 71L, as shown in Figure 8(b) and Figure 11(b). As shown in Figure 8(a), the focal point of the laser beam LB is positioned slightly above the tip surface 71La, but this is not limited to this position. Note that "molten portion" refers to the part obtained as a result of the metal melting. In Figure 8(b) and Figure 11(b), the tip surface 71La shown in Figure 8(a) and Figure 11(a) does not exist because the tip of the rectangular wire 71L has melted. In Figure 11(b), the position of the tip surface 71La is shown virtually.

[0059] The vibration of the laser beam LB irradiated onto the rectangular wires 71L and 71R is called wobbling. When irradiating the tip surface 71La of the rectangular wire 71L with the laser beam LB, the NC device 10 may control the galvanometer scanner 42 so that the laser beam LB traces a circle or ellipse in the central part of the tip surface 71La, instead of irradiating the laser beam LB to a fixed point which is the center of the tip surface 71La.

[0060] Figures 9 and 12 show the second step of the first irradiation pattern Pt1. The NC device 10 controls the galvanoscanner 42 to move the position from which the laser beam LB is irradiated from the tip surface 71La of the rectangular wire 71L to the tip surface 71Ra of the rectangular wire 71R. As shown in Figures 9(a) and 12(a), the laser welding machine 100 irradiates the center of the tip surface 71Ra of the rectangular wire 71R, which is the other of the pair of rectangular wires 71L and 71R, with the laser beam LB. At this time, the NC device 10 controls the blue laser oscillator 20 and the galvanoscanner 42 to irradiate the center of the tip surface 71Ra of the rectangular wire 71R with the laser beam LB.

[0061] As a result, the tip of the rectangular wire 71R melts, and a second molten portion 72R is formed on the rectangular wire 71R, as shown in Figure 9(b) and Figure 12(b). In Figure 9(b) and Figure 12(b), the tip surface 71Ra shown in Figure 9(a) and Figure 12(a) does not exist because the tip of the rectangular wire 71R has melted. In Figure 12(b), the position of the tip surface 71Ra is shown virtually. When irradiating the tip surface 71Ra of the rectangular wire 71R with a laser beam LB, the NC device 10 may control the galvanometer scanner 42 so that the laser beam LB traces a circle or ellipse in the center of the tip surface 71Ra, instead of irradiating the laser beam LB at a fixed point which is the center of the tip surface 71Ra.

[0062] The gap G is between 0 mm and less than 0.6 mm, and the rectangular wires 71L and 71R are in close proximity. Therefore, as shown in Figure 9(c) and Figure 12(c), the first molten portion 72L and the second molten portion 72R are naturally connected to form a bridge 73.

[0063] Figures 10 and 13 show the third step of the first irradiation pattern Pt1. As shown in Figure 10(a), the laser welding machine 100 irradiates the surface of the bridge 73 with the laser beam LB. The NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to irradiate the surface of the bridge 73 with the laser beam LB. As shown in Figure 13, the NC device 10 may control the galvanometer scanner 42 so that the laser beam LB traces an ellipse in the center of the bridge 73. Then, as shown in Figure 10(b), the amount of molten metal as the bridge 73 increases or the shape of the bridge 73 is refined, and the final bridge 74 is formed. By providing the third step, a predetermined molten shape of the bridge 74 can be stably formed.

[0064] The second irradiation pattern Pt2 will be specifically explained using Figures 14 to 21. Figures 14 to 17 are side views showing each step of the second irradiation pattern Pt2, and Figures 18 to 21 are plan views showing each step of the second irradiation pattern Pt2. In Figures 14 to 21, the gap amount G is 0.6 mm or more and 1.0 mm or less, and the positional displacement amount S is 0 mm.

[0065] Figures 14 and 18 show the first step of the second irradiation pattern Pt2. In the first step of the second irradiation pattern Pt2, as shown in Figure 14(b) and Figure 18(b), a first molten portion 72L is formed on the flat wire 71L, similar to the first step of the first irradiation pattern Pt1.

[0066] Figures 15 and 19 show the second step of the second irradiation pattern Pt2. In the second step of the second irradiation pattern Pt2, as shown in Figure 15(b) and Figure 19(b), a second molten portion 72R is formed on the rectangular wire 71R, similar to the second step of the first irradiation pattern Pt1. Because the gap amount G is 0.6 mm or more and 1.0 mm or less, and the rectangular wires 71L and 71R are relatively far apart, the first molten portion 72L and the second molten portion 72R are not connected, and a gap exists between the first molten portion 72L and the second molten portion 72R.

[0067] Figures 16 and 20 show the third step of the second irradiation pattern Pt2. The irradiation start position of the laser beam LB is set to a position on the surface of the second molten portion 72R that is shifted outward from the center of the tip surface 71Ra, opposite to the tip surface 71La. As shown in Figures 16(a) to 16(c), the NC device 10 controls the galvanoscanner 42 to move the laser beam LB from the irradiation start position toward the first molten portion 72L. As shown in Figures 16(b) and 20(b), in the third step, a portion of the molten metal of the second molten portion 72R, which has been melted by the irradiation of the laser beam LB, moves toward the first molten portion 72L. As a result, as shown in Figures 16(c) and 20(c), in the third step, a bridge 73 connecting the first molten portion 72L and the second molten portion 72R is formed.

[0068] In the third step, once the bridge 73 is formed, the irradiation end position of the laser beam LB can be any position. Since the bridge 73 is formed when the laser beam LB is moved from the irradiation start position toward the first molten portion 72L and the laser beam LB is still irradiating the second molten portion 72R, the irradiation end position can be any position on the second molten portion 72R. To more reliably form the bridge 73, the irradiation end position may be any position on the surface of the second molten portion 72R that corresponds to a position on the tip surface 71La side of the tip surface 71Ra side.

[0069] The irradiation end position may be any position on the surface of the first molten portion 72L. When the laser beam LB is moved to the first molten portion 72L, the first molten portion 72L also melts, thus further ensuring the formation of the bridge 73. In the example shown in Figure 16(c), the irradiation end position is set to a position on the surface of the first molten portion 72L corresponding to the center of the tip surface 71La. The irradiation end position may also be any position corresponding to the center of the tip surface 71La.

[0070] Thus, the NC device 10 sets the irradiation start position for the laser beam LB to a position on the surface of the second molten portion 72R that is shifted outward from the center of the tip surface 71Ra, opposite to the tip surface 71La. The NC device 10 controls the galvanometer scanner 42 to move the laser beam LB from the irradiation start position toward the first molten portion 72L.

[0071] Figures 17 and 21 show the fourth step of the second irradiation pattern Pt2. The fourth step of the second irradiation pattern Pt2 is the same as the third step of the first irradiation pattern Pt1. By providing the fourth step, the amount of molten metal as bridge 73 is increased or the shape of bridge 73 is refined, and the final bridge 74 is formed. By providing the fourth step, a predetermined molten shape of bridge 74 can be stably formed.

[0072] By the way, the welding in the first and second steps in the first irradiation pattern Pt1 and the first to third steps in the second irradiation pattern Pt2 is welding that generates metal vapor. The NC device 10 irradiates the surfaces of the flat wire 71L, the flat wire 71R, and the second molten part 72R with a laser beam LB, thereby controlling the blue laser oscillator 20 to generate metal vapor from the flat wire 71L, the flat wire 71R, and the second molten part 72R. The blue laser oscillator 20 emits a laser beam with sufficient laser power to generate metal vapor from the flat wire 71L, the flat wire 71R, and the second molten part 72R.

[0073] In the third step of the second irradiation pattern Pt2, suppose the laser beam LB is irradiated onto the second molten portion 72R, with the irradiation start position set to a position corresponding to the center of the tip surface 71Ra on the surface of the second molten portion 72R. Since the molten metal vapor Vp in the second molten portion 72R is ejected upward, the molten metal in the second molten portion 72R hardly moves to the first molten portion 72L. In contrast, if the laser beam LB is irradiated onto the second molten portion 72R with the irradiation start position set to a position shifted outward from the center of the tip surface 71Ra on the surface of the second molten portion 72R, the metal vapor Vp is biased outward and ejected diagonally upward. As a result, the molten metal in the second molten portion 72R can be moved to the first molten portion 72L.

[0074] The metal vapor Vp ejected outward and diagonally upward causes the molten metal in the second molten section 72R to move to the first molten section 72L, forming a bridge 73 that connects the first molten section 72L and the second molten section 72R. Therefore, it can be understood that in the third step of the second irradiation pattern Pt2, the irradiation end position of the laser beam LB does not necessarily have to be on the first molten section 72L.

[0075] The third irradiation pattern Pt3 will be specifically explained using Figures 22 to 25. Figures 22 to 25 are plan views showing each step of the third irradiation pattern Pt3. In Figures 22 to 25, the gap amount G is 0.6 mm or more and 1.0 mm or less, and the positional displacement amount S is 0.5 mm or more and 1.0 mm or less.

[0076] Figure 22 shows the first step of the third irradiation pattern Pt3. In the first step of the third irradiation pattern Pt3, as shown in Figure 22(b), a first molten portion 72L is formed on the flat wire 71L, similar to the first step of the second irradiation pattern Pt2. Due to the misalignment between the tip surface 71La and the tip surface 71Ra, the position of the first molten portion 72L is misaligned with the tip surface 71Ra.

[0077] Figure 23 shows the second step of the third irradiation pattern Pt3. In the second step of the third irradiation pattern Pt3, as shown in Figure 23(b), a second molten portion 72R is formed on the flat wire 71R, similar to the second step of the second irradiation pattern Pt2. The positions of the first molten portion 72L and the second molten portion 72R are offset, and the first molten portion 72L and the second molten portion 72R are not connected.

[0078] Figure 24 shows the third step of the third irradiation pattern Pt3. In the third step of the third irradiation pattern Pt3, as shown in Figure 24(a), the NC device 10 controls the galvanoscanner 42 to move the laser beam LB from the irradiation start position on the second melting section 72R towards the first melting section 72L, similar to the third step of the second irradiation pattern Pt2. At this time, unlike the third step of the second irradiation pattern Pt2, the NC device 10 controls the galvanoscanner 42 to move the laser beam LB while causing the beam spot Bs to wobble in a circular motion.

[0079] The circle drawn by the beam spot Bs is the pattern when the laser beam LB is not moving. The galvanoscanner 42 displaces the laser beam LB to draw a circle while moving it, so the actual pattern is the displacement that draws the circle plus the displacement in the direction of movement of the laser beam LB.

[0080] The pattern that causes the laser beam LB to wobble is not limited to a circle. The pattern that causes the laser beam LB to wobble is any pattern that includes a component perpendicular to the direction of movement of the laser beam LB from the second molten section 72R to the first molten section 72L. When expressed as a pattern when the laser beam LB is not moving, the wobbling pattern may be a straight line perpendicular to the direction of movement of the laser beam LB, or it may be an ellipse, the number 8 (or the infinity symbol), or a spiral. For an ellipse, the major axis should be in the direction perpendicular to the direction of movement. For the number 8, it is best to draw it so that the direction perpendicular to the direction of movement is the height direction of the number 8. For the infinity symbol, it is best to draw it along the direction perpendicular to the direction of movement so that the direction of movement is the height direction of the infinity symbol.

[0081] As shown in Figure 24(b), in the third step, a portion of the molten metal in the second molten section 72R, which has been melted by irradiation with the laser beam LB, moves to the first molten section 72L. By wobbling the laser beam LB in a pattern that includes a component perpendicular to the direction of movement, the second molten section 72R becomes more easily melted over a wide area and in a short time in the component perpendicular to the direction of movement. As a result, as shown in Figure 24(c), even if the positions of the first molten section 72L and the second molten section 72R are misaligned in the third step, a bridge 73 connecting the first molten section 72L and the second molten section 72R is formed well.

[0082] Figure 25 shows the fourth step of the third irradiation pattern Pt3. The fourth step of the third irradiation pattern Pt3 is the same as the fourth step of the second irradiation pattern Pt2. As can be seen by comparing Figure 24(c) and Figure 25, the shape of the bridge 73 is refined by the fourth step, and the final bridge 74 is formed.

[0083] In addition to setting the irradiation conditions as described above, the irradiation conditions may also be set in accordance with the height difference H of the tip surfaces 71La and 71Ra. Regardless of the height difference H, the NC device 10 selects the first irradiation pattern Pt1 to the third irradiation pattern Pt3 as described above. In this case, the NC device 10 may control the galvanoscanner 42 so that in the first step, in any of the first irradiation patterns Pt1 to the third irradiation pattern Pt3, the laser beam LB is irradiated first to the tip surface that is higher than the tip surface 71La and the tip surface 71Ra. Furthermore, the NC device 10 may make the irradiation time of the laser beam LB to the tip surface that is higher than the irradiation time to the tip surface that is lower. This makes it possible to reduce the inclination of the surface of the bridge 74 when the bridge 74 solidifies.

[0084] If the areas of the tip surfaces 71La and 71Ra are different, the NC device 10 should control the irradiation time of the laser beam LB in the first process and the irradiation time in the second process according to the difference in area. As the areas of the tip surfaces 71La and 71Ra increase, it is preferable to wobble the laser beam LB to widen the irradiation area and melt the metal over a wider area.

[0085] In the first irradiation pattern Pt1 to the third irradiation pattern Pt3 described above, the laser beam LB is irradiated onto the tip surface 71La of the flat wire 71L in the first step, and the laser beam LB is irradiated onto the tip surface 71Ra of the flat wire 71R in the second step. Alternatively, the laser beam LB may be irradiated onto the tip surface 71Ra of the flat wire 71R in the first step, and the laser beam LB may be irradiated onto the tip surface 71La of the flat wire 71L in the second step. That is, the first tip surface of the first flat wire may be the tip surface 71Ra of the flat wire 71R, and the second tip surface of the second flat wire may be the tip surface 71La of the flat wire 71L.

[0086] In this case, in the third step of the second irradiation pattern Pt2 and the third irradiation pattern Pt3, the irradiation start position of the laser beam LB may be set to a position on the surface of the first molten portion 72L that is shifted outward from the center of the tip surface 71La, opposite to the tip surface 71Ra. In addition, the laser beam LB may be moved from the irradiation start position toward the second molten portion 72R. The irradiation end position of the laser beam LB may be set to a position on the first molten portion 72L, or to a position on the surface of the first molten portion 72L that is on the tip surface 71Ra side of the end of the tip surface 71La. The irradiation end position may be set to a position on the surface of the second molten portion 72R, or to a position corresponding to the center of the tip surface 71Ra.

[0087] In the example described above, there are three types of irradiation patterns: the first irradiation pattern Pt1 to the third irradiation pattern Pt3. However, the NC device 10 only needs to be configured to allow selection of at least two types of irradiation patterns.

[0088] Thus, the NC device 10 selects one of several irradiation conditions for irradiating the tip surfaces 71La and 71Ra with a laser beam LB to weld each pair of rectangular wires 71L and 71R, corresponding to at least one of the gap amount G and the misalignment amount S between each pair of rectangular wires 71L and 71R. The NC device 10 creates a processing program to weld multiple pairs of rectangular wires 71L and 71R using the selected irradiation condition for each pair of rectangular wires 71L and 71R. The NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to weld multiple pairs of rectangular wires 71L and 71R according to the created processing program.

[0089] Therefore, according to the laser welding machine 100, the laser welding method performed by the laser welding machine 100, and the processing program creation method, even if the gap amount G or positional displacement S of the pair of flat wires 71L and 71R vary, the occurrence of welding defects can be reduced and the cycle time can be shortened. By selecting irradiation conditions corresponding to the combination of gap amount G and positional displacement S, more favorable irradiation conditions can be selected. It is preferable to set an irradiation pattern for each irradiation condition. It is preferable to set the number of processes for welding the pair of flat wires 71L and 71R and the trajectory pattern irradiated onto each pair of flat wires 71L and 71R in each process in the irradiation pattern. By setting the irradiation pattern (number of processes and trajectory pattern) corresponding to the gap amount G or positional displacement S, the occurrence of welding defects can be reduced more effectively.

[0090] Here, the setting of monitoring conditions in the monitoring device 55 will be explained. The monitoring device 55 selects the wavelength to be monitored depending on whether visible light, near-infrared light, or reflected light from the laser beam LB is to be used as the detection light to determine the quality of the weld. The monitoring device 55 determines the quality of the weld based on the count value of the amount of light of the detection light received by the light receiving unit 35.

[0091] The monitoring conditions M1 to M3 may have different time settings required to determine the quality of the weld. It is preferable to make the time settings in monitoring condition M2 when using the second irradiation pattern Pt2 and monitoring condition M3 when using the third irradiation pattern Pt3 longer than the time settings in monitoring condition M1 when using the first irradiation pattern Pt1.

[0092] The NC device 10 selects monitoring conditions for determining the quality of the weld of each pair of flat wires 71L and 71R in the monitoring device 55, corresponding to at least one of the gap amount G and the misalignment amount S. The NC device 10 instructs the monitoring device 55 to determine the quality of the weld of each pair of flat wires 71L and 71R using the selected monitoring conditions. Therefore, with the laser welding machine 100, even if the gap amount G or misalignment amount S of each pair of flat wires 71L and 71R varies, the quality of the weld of each pair of flat wires 71L and 71R can be accurately determined. Because the quality of the weld of each pair of flat wires 71L and 71R can be accurately determined, the occurrence of welding defects can be reduced.

[0093] The NC device 10 may select monitoring conditions in the monitoring device 55 to determine the quality of the weld of each pair of flat wires 71L and 71R, corresponding to the combination of the gap amount G and the positional displacement amount S. The NC device 10 instructs the monitoring device 55 to determine the quality of the weld of each pair of flat wires 71L and 71R using the selected monitoring conditions. In this way, the monitoring device 55 can more accurately determine the quality of the weld of each pair of flat wires 71L and 71R.

[0094] Furthermore, it is preferable to set the monitoring conditions in the monitoring device 55 in accordance with the positions of the pair of rectangular wires 71L and 71R on the rotating body 110, as follows.

[0095] Figures 26(a) to (c) show typical light intensity count values ​​when welding the flat wire pairs 71CTR, 71OS, and 71IS shown in Figure 6A, respectively. The light intensity count value is an example of a quantitative value based on the electrical signal obtained by the monitoring device 55 by photoelectric conversion of the input detected light. The maximum light intensity count value when welding the radially outer flat wire pair 71OS is smaller than the maximum light intensity count value when welding the radially central flat wire pair 71CTR. The maximum light intensity count value when welding the radially inner flat wire pair 71IS is smaller than the maximum light intensity count value when welding the flat wire pair 71OS. The monitoring device 55 determines that there is a welding defect if the light intensity count value exceeds a predetermined threshold TH. The monitoring device 55 should determine that there is a welding defect based on the quantitative value obtained based on the detected light.

[0096] If a common threshold TH is used for flat wire pairs 71CTR, 71OS, and 71IS, it is not possible to correctly determine whether a welding defect exists for all flat wire pairs 71CTR, 71OS, and 71IS. Therefore, when welding flat wire pairs 71CTR, the monitoring device 55 uses the threshold THa to determine whether a welding defect exists. When welding flat wire pairs 71OS, the monitoring device 55 uses the threshold THb to determine whether a welding defect exists, and when welding flat wire pairs 71IS, the threshold THc is used to determine whether a welding defect exists. The threshold THb is smaller than the threshold THa, and the threshold THc is smaller than the threshold THb.

[0097] The condition table stored in the memory unit 11 may include threshold values ​​TH that vary depending on the position of each pair of rectangular lines 71L and 71R within the irradiation area where the galvanoscanner 42 displaces the laser beam to irradiate each pair of rectangular lines 71L and 71R with the laser beam.

[0098] The condition table may include a gain that is multiplied by the light intensity count value according to the position of the pair of flat wires 71L and 71R within the irradiation area. In this case, the monitoring device 55 determines whether or not there is a welding defect using the same threshold TH, regardless of the position of the pair of flat wires 71L and 71R within the irradiation area.

[0099] Figures 27(a) to (c), similar to Figures 26(a) to (c), show standard light intensity count values ​​when welding the flat wire pairs 71CTR, 71OS, and 71IS shown in Figure 6A, respectively. For example, suppose the light intensity count value when welding the flat wire pair 71OS is only 70% of the light intensity count value when welding the flat wire pair 71CTR, and the light intensity count value when welding the flat wire pair 71IS is only 60% of the light intensity count value when welding the flat wire pair 71CTR. If we multiply the light intensity count value when welding the flat wire pair 71CTR by a gain of 1, the light intensity count value when welding the flat wire pair 71OS by a gain of 10 / 7, and the light intensity count value when welding the flat wire pair 71IS by a gain of 10 / 6, the maximum value of the light intensity count value will be approximately the same.

[0100] The monitoring device 55 can determine whether or not a welding defect has occurred based on whether or not the light intensity count value when welding the pair of rectangular wires 71CTR, 71OS, and 71IS exceeds a common threshold TH. The condition table stored in the storage unit 11 can be set with the threshold TH and gains of different values ​​depending on the positions of the pair of rectangular wires 71L and 71R within the irradiation area.

[0101] The monitoring conditions M1 to M3 shown in Figure 7 may have different threshold values ​​TH for determining whether or not there is a welding defect, or different gain values ​​multiplied by the light intensity count value, depending on the position of the pair of flat wires 71L and 71R within the irradiation area.

[0102] The setting of monitoring conditions when welding a group of pairs of rectangular wires 71L and 71R while the rotating body 110 is stopped will be explained in more detail. As explained in Figure 6A, the center of the focusing lens 43 is located directly above the central pair of rectangular wires 71CTR of the three pairs of rectangular wires 71L and 71R, and the laser welding machine 100 welds the pairs of rectangular wires 71CTR, 71OS, and 71IS in order as a group of pairs of rectangular wires 71L and 71R. The intensity of the detection light received by the light receiving unit 35 when the processing head 40 is irradiating the pair of rectangular wires 71CTR with the laser beam LB is different from the intensity of the detection light received by the light receiving unit 35 when the laser beam LB is irradiating the outer-circumferential pair of rectangular wires 71OS or the inner-circumferential pair of rectangular wires 71IS.

[0103] As explained in Figure 6B, the center of the focusing lens 43 is located directly above the central pair of flat wires 71L and 71R of the nine pairs of flat wires 71L and 71R, and the laser welding machine 100 sequentially welds the nine pairs of flat wires 71L and 71R as a group of pairs of flat wires 71L and 71R. The intensity of the detection light received by the light receiving unit 35 when the processing head 40 is irradiating the central pair of flat wires 71L and 71R with the laser beam LB is different from the intensity of the detection light received by the light receiving unit 35 when the laser beam LB is irradiating the surrounding pair of flat wires 71L and 71R.

[0104] Therefore, the monitoring device 55 should determine the quality of the welding of each pair of rectangular wires 71L and 71R using different monitoring conditions depending on the position of each pair of rectangular wires 71L and 71R within the irradiation area where the laser beam displaced by the galvanoscanner 42 is irradiated, including multiple pairs of rectangular wires 71L and 71R. That is, taking Figure 6B as an example, even if the combination of gap amount G and displacement amount S for the central pair of rectangular wires 71L and 71R is the same as the combination of gap amount G and displacement amount S for the surrounding pair of rectangular wires 71L and 71R, the monitoring conditions should be different.

[0105] As shown in Figure 28, the area where nine pairs of rectangular wires 71L and 71R are arranged is defined as the irradiation area G71. Each pair of rectangular wires 71L and 71R is positioned in one of nine areas Ar1 to Ar9, obtained by dividing the irradiation area G71 into nine sections. The irradiation area G71 is the range in which the laser welding machine 100 sequentially welds each pair of rectangular wires 71L and 71R while displacing the laser beam with the galvanometer scanner 42 during the stopping period when the rotating body 110 is stopped. As shown in Figure 6A, the irradiation area may also include three pairs of rectangular wires 71L and 71R. As the rotating body 110 rotates at predetermined angles, a group of pairs of rectangular wires 71L and 71R included in the irradiation area move sequentially.

[0106] The condition table stored in the memory unit 11 may contain monitoring conditions for determining the quality of welding corresponding to areas Ar1 to Ar9 of the irradiation region G71 shown in Figure 28, that is, the positions where a pair of flat wires 71L and 71R are located within the irradiation region G71. As monitoring conditions for areas Ar1 to Ar9, a threshold TH to be compared with the detected light may be set for each area, or a gain to be multiplied by the detected light may be set for each area. There may be areas within the irradiation region G71 with the same monitoring conditions.

[0107] In this way, with the rotating body 110 fixed, a region including a group of pairs of flat wires 71L and 71R, which is at least a part of the multiple pairs of flat wires 71L and 71R on the rotating body 110, is defined as an irradiation region where the galvanometer scanner 42 displaces the laser beam LB to irradiate each pair of flat wires 71L and 71R in the group of pairs of flat wires 71L and 71R with the laser beam LB. The monitoring device 55 selects monitoring conditions to determine the quality of the welding corresponding to the position of each pair of flat wires 71L and 71R in the irradiation region, and determines the quality of the welding of each pair of flat wires 71L and 71R based on the selected monitoring conditions. In this way, the quality of the welding of each pair of flat wires 71L and 71R in the multiple pairs of flat wires 71L and 71R can be accurately determined.

[0108] The NC device 10 may maintain a condition table in which monitoring conditions are set corresponding to the positions of each pair of flat wires 71L and 71R within the irradiation area. The NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to sequentially irradiate each pair of flat wires 71L and 71R within the irradiation area with the laser beam LB. The NC device 10 may refer to the condition table and select monitoring conditions corresponding to the positions of each pair of flat wires 71L and 71R within the irradiation area to which the laser beam is irradiated. The NC device 10 may instruct the monitoring device 55 to determine the quality of the welding of each pair of flat wires 71L and 71R based on the selected monitoring conditions.

[0109] By setting monitoring conditions in the condition table, the NC device 10 can easily select monitoring conditions corresponding to the position within the irradiation area of ​​the pair of flat rectangular wires 71L and 71R that are irradiated with the laser beam.

[0110] The setting of monitoring conditions when welding each pair of rectangular wires 71L and 71R while the rotating body 110 is rotating will be explained in more detail. When the rotating body 110 is rotated to select the pair of rectangular wires 71L and 71R to be welded, each pair of rectangular wires 71L and 71R is not necessarily located directly below the focusing lens 43. The positional relationship between the focusing lens 43 and the pair of rectangular wires 71L and 71R on the outer circumference, the positional relationship between the focusing lens 43 and the pair of rectangular wires 71L and 71R on the central circumference, and the positional relationship between the focusing lens 43 and the pair of rectangular wires 71L and 71R on the inner circumference are all different from each other. Even if the pair of rectangular wires 71L and 71R are within the same circumference, if the circumferential arrangement is irregular, the positional relationship between the focusing lens 43 and the pair of rectangular wires 71L and 71R will vary depending on the circumferential position.

[0111] Therefore, even when selecting a pair of rectangular wires 71L and 71R to be welded while rotating the rotating body 110, and welding each pair of rectangular wires 71L and 71R, the intensity of the detected light received by the light receiving unit 35 varies depending on the position of the pair of rectangular wires 71L and 71R on the rotating body 110. Thus, similar to the state when the rotating body 110 is fixed, a region including a group of pairs of rectangular wires 71L and 71R, which is at least a portion of the multiple pairs of rectangular wires 71L and 71R on the rotating body 110, is designated as an irradiation region where the galvanometer scanner 42 displaces the laser beam LB to irradiate each pair of rectangular wires 71L and 71R in the group of rectangular wires 71L and 71R with the laser beam LB. As the rotating body 110 rotates, the group of pairs of rectangular wires 71L and 71R included in the irradiation region move sequentially.

[0112] The monitoring device 55 may determine the quality of the welding of each pair of flat wires 71L and 71R under different monitoring conditions depending on their positions within the irradiation area. Even if the combination of gap amount G and positional displacement amount S is the same for one pair of flat wires 71L and 71R and another pair of flat wires 71L and 71R, the monitoring conditions should be different because their positions within the irradiation area are different.

[0113] The NC device 10 may maintain a condition table in which monitoring conditions are set corresponding to the positions of each pair of flat wires 71L and 71R within the irradiation area. The NC device 10 controls the blue laser oscillator 20 and the galvanometer scanner 42 to sequentially irradiate each pair of flat wires 71L and 71R within the irradiation area with the laser beam LB. The NC device 10 may refer to the condition table and select monitoring conditions corresponding to the positions of each pair of flat wires 71L and 71R within the irradiation area to which the laser beam is irradiated. The NC device 10 may instruct the monitoring device 55 to determine the quality of the weld of each pair of flat wires 71L and 71R based on the selected monitoring conditions.

[0114] Thus, the monitoring device 55 can select monitoring conditions corresponding to the position of each pair of flat wires 71L and 71R within the irradiation area, regardless of whether each pair of flat wires 71L and 71R is welded with the rotating body 110 fixed or while rotating. The monitoring device 55 selects monitoring conditions corresponding to the position of each pair of flat wires 71L and 71R within the irradiation area and determines the quality of the weld of each pair of flat wires 71L and 71R based on the selected monitoring conditions.

[0115] By the way, in the condition table shown in Figure 7, if the gap amount G exceeds 1.0 mm (an example of an upper limit) or the displacement amount S exceeds 1.0 mm (an example of an upper limit), "0" is set as the irradiation pattern, indicating that the pair of flat wires 71L and 71R will not be welded. Therefore, as shown in Figure 29, when welding of multiple pairs of flat wires 71L and 71R is completed, it is possible that the gap amount G or displacement amount S between a pair of flat wires 71L and 71R at a certain location exceeds the upper limit and is not welded.

[0116] In this case, the gap between the unwelded pair of rectangular wires 71L and 71R may be narrowed or the misalignment corrected using tools, and then they may be manually welded using a handheld welding machine. In this way, a motor with multiple pairs of rectangular wires 71L and 71R can be made into a good motor. Suppose all pairs of rectangular wires 71L and 71R, including the pair of rectangular wires 71L and 71R whose gap amount G or misalignment amount S exceeds the upper limit, are welded using the laser welding machine 100. Then, the pair of rectangular wires 71L and 71R whose gap amount G or misalignment amount S exceeds the upper limit will be defectively welded, resulting in a defective motor.

[0117] By setting a value in the condition table that indicates that welding will not be performed if the gap amount G or the misalignment amount S exceeds an upper limit, the occurrence of welding defects in motors can be reduced.

[0118] Furthermore, a specific example will be described in which the NC device 10 performs control to weld each pair of rectangular wires 71L and 71R with processing conditions corresponding to the positions of each pair of rectangular wires 71L and 71R in a group of pairs of rectangular wires 71L and 71R, based on the detection light monitored by the monitoring device 55. As shown in Figure 30, the bridge 74 connecting the ends of the pair of rectangular wires 71L and 71R becomes a hemispherical molten ball MB. It is desirable that the ends of the pair of rectangular wires 71L and 71R melt appropriately without under-melting or over-melting, so that a molten ball MB of an appropriate size is formed.

[0119] Let's take the case of welding the flat wire pairs 71CTR, 71OS, and 71IS shown in Figure 6A as an example. When the laser beam LB is irradiated onto the flat wire pairs 71CTR, 71OS, and 71IS, the intensity of the detected light received by the light receiving unit 35 is different from that of the other. The amount of energy irradiated onto the pair of flat wires 71L and 71R can be represented by the integral value of the light quantity count value and time, that is, by the area of ​​the hatched region in the waveform diagrams shown in Figures 31(a) to (c). Figures 31(a) to (c) show the integral values ​​when a molten ball MB of an appropriate size is formed by welding the flat wire pairs 71CTR, 71OS, and 71IS in a standard welding process.

[0120] The integral values ​​for welding pairs of rectangular wires 71CTR, 71OS, and 71IS to form molten ball MBs of appropriate size are assumed to be 1000, 800, and 600, respectively. The integral values ​​of 1000, 800, and 600 are target integral values ​​for forming molten ball MBs of appropriate size. In standard welding, the time required for the formation of molten ball MBs of appropriate size is defined as the standard time T1, from the start time t0 to time t1. Depending on various conditions such as the state of the shielding gas and ambient temperature during welding, welding a pair of rectangular wires 71L and 71R for only the standard time T1 may result in over-welding and an excessively large molten ball MB, while welding for only the standard time T1 may result in insufficient melting and an inappropriately sized molten ball MB.

[0121] In Figure 32, (a) shows the state in which the integral value reaches 800 at time t2, prior to time t1, during the welding of the flat wire pair 71OS. The NC device 10 controls the blue laser oscillator 20 to stop irradiating the flat wire pair 71OS with the laser beam LB at time t2, when the integral value of the light quantity count value based on the light detected by the monitoring device 55 and time reaches 800. The irradiation time of the laser beam LB at this time is shorter than the standard time T1, which is time T2. Since the integral value is the target integral value of 800, a molten ball MB of an appropriate size is formed in the flat wire pair 71OS.

[0122] In Figure 32, (b) shows a state in which, during welding of the flat wire pair 71IS, the integrated value does not reach 600 even when the laser beam LB is irradiated onto the flat wire pair 71IS for a standard time T1. The NC device 10 controls the blue laser oscillator 20 to continue irradiating the flat wire pair 71IS with the laser beam LB even after the standard time T1 has passed, because the integrated value of the light quantity count value based on the light detected by the monitoring device 55 and time has not reached 600 at time t1. The NC device 10 controls the blue laser oscillator 20 to stop irradiating the flat wire pair 71IS with the laser beam LB at time t3 when the integrated value reaches 600. The irradiation time of the laser beam LB at this time is longer than the standard time T1, which is time T3. Since the integrated value is the target integrated value of 600, a molten ball MB of an appropriate size is formed on the flat wire pair 71IS.

[0123] The target integral value for forming a molten ball MB of appropriate size by welding a pair of rectangular wires 71L and 71R should be a value corresponding to the gap amount G. The integral value 800 for forming a molten ball MB of appropriate size in the above pair of rectangular wires 71OS is assumed to be the target integral value when the gap amount G is 0.4 mm. If the gap amount G is 0.8 mm, the target integral value should be 1000, and if the gap amount G is 1.0 mm, the target integral value should be 1300; the target integral value should be increased as the gap amount G increases.

[0124] The NC device 10 should control the blue laser oscillator 20 in the same way when the target integral value is 1000 or 1300. If the target integral value of 1000 or 1300 is reached in a time shorter than the standard time T1 required to reach 1000 or 1300, the NC device 10 controls the blue laser oscillator 20 to stop irradiating the laser beam LB at that point. If the target integral value of 1000 or 1300 is reached in a time longer than the standard time T1 required to reach 1000 or 1300, the NC device 10 controls the blue laser oscillator 20 to stop irradiating the laser beam LB at that point.

[0125] Thus, the NC device 10 may control the blue laser oscillator 20 to weld each pair of flat wires 71L and 71R with processing conditions corresponding to the positions of each pair of flat wires 71L and 71R within the irradiation area, based on the detected light monitored by the monitoring device 55. When the NC device 10 controls the blue laser oscillator 20, it may use quantitative values ​​such as light quantity count values ​​based on the detected light. Instead of controlling the irradiation time of the laser beam LB, the NC device 10 may control the laser output of the blue laser oscillator 20. To adjust the focal position of the laser beam LB, the focusing lens 43 may be configured to move freely in the optical axis direction. The focal position may be set as a processing condition corresponding to the positions of each pair of flat wires 71L and 71R within the irradiation area.

[0126] The NC device 10 controls the monitoring device 55 to monitor the detected light under monitoring conditions based on the detected light, or controls the blue laser oscillator 20 to weld each pair of flat wires 71L and 71R under processing conditions based on the detected light. At this time, the NC device 10 controls the monitoring device 55 or the blue laser oscillator 20 based on a light quantity count value indicating the intensity of the detected light. The NC device 10 may also control the monitoring device 55 or the blue laser oscillator 20 based on the integral value of the detected light, or based on the rate of change of the detected light.

[0127] The present invention is not limited to the one or more embodiments described above, and can be modified in various ways without departing from the spirit of the invention.

[0128] This application claims priority based on Japanese Patent Application No. 2024-227854, filed with the Japan Patent Office on 24 December 2024, and Japanese Patent Application No. 2025-250841, filed with the Japan Patent Office on 15 December 2025, all disclosures thereof are incorporated herein by reference.

Claims

1. A laser oscillator that emits a laser beam; a processing head that irradiates the laser beam emitted from the laser oscillator onto the tip surfaces of each pair of rectangular wires in a plurality of pairs of rectangular wires to weld each pair of rectangular wires; a displacement mechanism that displaces the laser beam irradiating each pair of rectangular wires; a sensing device that senses each pair of rectangular wires in order to obtain at least one of the gap amount between each pair of rectangular wires and the positional displacement amount between each pair of rectangular wires in the direction along the mutually opposing sides of the tip surfaces of each pair of rectangular wires; A laser welding machine comprising: a control device that controls the laser oscillator and the displacement mechanism to weld the multiple pairs of flat wires, corresponding to at least one of the gap amount between each pair of flat wires and the positional displacement amount between each pair of flat wires obtained as a result of sensing each pair of flat wires by the sensing device, selecting one of a plurality of irradiation conditions for irradiating the tip surface of each pair of flat wires with the laser beam in order to weld each pair of flat wires, creating a processing program for welding the multiple pairs of flat wires with the selected irradiation condition for each pair of flat wires, and welding the multiple pairs of flat wires according to the created processing program.

2. The laser welding machine according to claim 1, wherein the sensing device senses each pair of rectangular wires in order to obtain both the amount of gap and the amount of misalignment between each pair of rectangular wires, and the control device selects irradiation conditions for irradiating the tip faces of each pair of rectangular wires with the laser beam in accordance with the combination of the amount of gap and the amount of misalignment between each pair of rectangular wires obtained as a result of the sensing device sensing each pair of rectangular wires.

3. The laser welding machine according to claim 1 or 2, wherein each of the plurality of irradiation conditions is set to an irradiation pattern in which the laser beam is irradiated onto the tip surfaces of each pair of flat wires.

4. The laser welding machine according to claim 3, wherein the irradiation pattern is set to include the number of steps for welding each pair of flat wires and the trajectory pattern of the laser beam irradiated onto each pair of flat wires in each step.

5. The laser welding machine according to claim 1, wherein the sensing device includes a camera, and the control device obtains at least one of the gap amount and the positional displacement amount based on the captured images of each pair of rectangular lines captured by the camera.

6. The laser welding machine according to claim 1, further comprising a monitoring device for monitoring detection light, which is at least one of reflected light, emitted visible light, or emitted near-infrared light of the laser beam, while welding each pair of flat wires, wherein the control device performs control related to welding each pair of flat wires based on the detection light monitored by the monitoring device.

7. The laser welding machine according to claim 6, wherein the control device sets monitoring conditions for the monitoring device to monitor the detected light, and the monitoring device determines the quality of the welding of each pair of flat wires based on the detected light under the set monitoring conditions.

8. The laser welding machine according to claim 6, wherein the control device controls the laser oscillator to weld each pair of flat wires with processing conditions set for each pair of flat wires based on the detected light.

9. The laser welding machine according to claim 7, wherein the control device selects monitoring conditions for determining the quality of the welding of each pair of flat wires in the monitoring device, corresponding to at least one of the gap amount and the positional displacement amount, and commands the monitoring device to determine the quality of the welding of each pair of flat wires using the selected monitoring conditions.

10. A laser welding machine according to claim 7 or 8, wherein a region including a group of pairs of flat wires, which is at least a part of the plurality of pairs of flat wires, is an irradiation region in which the displacement mechanism displaces the laser beam to irradiate each pair of flat wires in the group of pairs of flat wires, the control device selects monitoring conditions for determining the quality of the welding corresponding to the position of each pair of flat wires in the irradiation region, and commands the monitoring device to determine the quality of the welding of each pair of flat wires according to the selected monitoring conditions.

11. The laser welding machine according to claim 10, wherein the control device maintains a condition table in which monitoring conditions are set corresponding to the positions of each pair of flat wires within the irradiation area in the group of pairs of flat wires, and by referring to the condition table, selects a monitoring condition corresponding to the position of each pair of flat wires within the irradiation area that is irradiated with the laser beam from the group of pairs of flat wires, and commands the monitoring device to determine the quality of the welding of each pair of flat wires using the selected monitoring condition.

12. A laser welding method comprising: sensing each pair of flat wires in a plurality of pairs of flat wires to be welded using a sensing device; obtaining at least one of the gap amount between each pair of flat wires and the displacement amount between each pair of flat wires in the direction along the opposing sides of the tip faces of each pair of flat wires; selecting one of a plurality of irradiation conditions for irradiating the tip faces of each pair of flat wires with a laser beam in accordance with at least one of the gap amount and the displacement amount; and welding the plurality of pairs of flat wires with the irradiation condition selected for each pair of flat wires in the plurality of pairs of flat wires.

13. The laser welding method according to claim 12, wherein the sensing device acquires both the gap amount and the positional displacement amount, and selects one of the plurality of irradiation conditions corresponding to the combination of the gap amount and the positional displacement amount.

14. A method for creating a processing program, comprising: sensing each pair of flat wires in a plurality of pairs of flat wires to be welded using a sensing device; obtaining at least one of the gap amount between each pair of flat wires and the positional displacement amount between each pair of flat wires in the direction along the opposing sides of the tip faces of each pair of flat wires; selecting one of a plurality of irradiation conditions for irradiating the tip faces of each pair of flat wires with a laser beam in accordance with at least one of the gap amount and the positional displacement amount; and creating a processing program for welding the plurality of pairs of flat wires using the irradiation condition selected for each pair of flat wires in the plurality of pairs of flat wires.

15. The method for creating a processing program according to claim 14, wherein the sensing device acquires both the gap amount and the positional displacement amount, and selects one of the multiple irradiation conditions corresponding to the combination of the gap amount and the positional displacement amount.

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