Laser welding device and laser welding method

Abstract

The laser welding device includes: a laser oscillator; a processing head that performs two-dimensional scanning of the laser light while traveling along a welding line having a curved portion, and that irradiates the laser light on the surface of the workpiece so as to periodically draw a predetermined pattern; and a controller for controlling the movement of the processing head and the two-dimensional scanning of the laser. The two-dimensional scanning of the laser light at the curved section is controlled such that a first overlap ratio indicating an overlap ratio of the pattern on one side obtained by the periodic drawing of the pattern at the curved section is the same as a second overlap ratio indicating an overlap ratio of the pattern on the other side obtained by the periodic drawing of the pattern at the curved section.

Description

TECHNICAL FIELD

[0001] The present application relates to a laser welding apparatus and a laser welding method. BACKGROUND

[0002] A laser welding method is disclosed in Patent Literature 1, which overlaps a plurality of metal sheets including plated metal sheets in which a low-boiling-point metal having a lower boiling point than a melting point of a base material is plated, and welds the plurality of metal sheets by irradiating laser light to an overlapping portion of the metal sheets. The laser light delivered from a laser oscillator is irradiated to the overlapping portion by a scanner machining head while adjusting a focal point.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent No. 4915315 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The present application has been achieved in view of the foregoing circumstances, and provides a laser welding apparatus and a laser welding method in which heat input of laser light is balanced uniformly on the inside and the outside in laser welding along a welding line having a curved shape, and degradation of a weld bead is suppressed.

[0008] MEANS FOR SOLVING THE PROBLEMS

[0009] The present application provides a laser welding apparatus, wherein the laser welding apparatus includes a laser oscillator that generates laser light, a machining head that causes the laser light to be scanned two-dimensionally while traveling along a welding line having at least a curved portion, and irradiates the laser light to a surface of a workpiece in a manner of periodically drawing a prescribed pattern, and a controller that controls movement of the machining head along the welding line and two-dimensional scanning of the laser light, the controller controlling two-dimensional scanning of the laser light at the curved portion in a manner that a first overlap ratio representing an overlap ratio of the pattern on one side based on periodic drawing of the pattern at the curved portion is the same as a second overlap ratio representing an overlap ratio of the pattern on the other side based on periodic drawing of the pattern at the curved portion.

[0010] Further, the present application provides a laser welding method executed by a laser welding apparatus having at least a laser oscillator that generates laser light, a machining head, and a controller, and having a step of causing the laser light to be irradiated to a surface of a workpiece in a manner of periodically tracing a prescribed pattern by two-dimensionally scanning the laser light while the laser light travels along a welding line having at least a curved portion, and a step of controlling movement of the machining head along the welding line and two-dimensional scanning of the laser light, in the step of controlling the two-dimensional scanning of the laser light, the two-dimensional scanning of the laser light at the curved portion is controlled in a manner that a first overlap ratio representing an overlap ratio of the pattern on one side based on the periodic tracing of the pattern at the curved portion is identical to a second overlap ratio representing an overlap ratio of the pattern on the other side based on the periodic tracing of the pattern at the curved portion.

[0011] Effects of Invention

[0012] According to the present application, in laser welding along a welding line having a curved shape, heat input on the inner side and the outer side can be balanced uniformly, and deterioration of the quality of the weld bead can be suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a view showing a schematic configuration example of a laser welding apparatus of the present embodiment.

[0014] Figure 2 is a view schematically showing a configuration example of a galvanometer head.

[0015] Figure 3 is a view showing an example of a Lissajous pattern as an example of a scanning pattern of laser light.

[0016] Figure 4 is a view showing overlap ratios of an upper portion of a welding line and a lower portion of the welding line at the time of straight line welding.

[0017] Figure 5 is a view showing overlap ratios of an upper portion of a welding line and a lower portion of the welding line at the time of curved line welding of the related art.

[0018] Figure 6 is a view showing overlap ratios of an upper portion of a welding line and a lower portion of the welding line at the time of curved line welding of the present embodiment.

[0019] Figure 7 is a view showing an example of a laser welding pattern of the present embodiment.

[0020] Figure 8 is a flowchart showing an example of an operation sequence of laser welding of the laser welding apparatus of the present embodiment in time series.

[0021] Figure 9A is a view showing an example of a pattern of the first modified example.

[0022] Figure 9B FIG. 1 is a diagram showing an example of a pattern of a second modification example.

[0023] Figure 9C FIG. 2 is a diagram showing an example of a pattern of a third modification example. DETAILED DESCRIPTION

[0024] (Process of completing the present application)

[0025] The laser has a high power density, and can perform high-speed and high-quality welding, and is applied to welding of various workpieces. In particular, in scan welding in which the laser is scanned at high speed on the surface of the workpiece while welding is performed, the laser beam can be moved at high speed to the next welding point during a period in which welding is not performed, and thus the total welding time can be shortened (see, for example, Patent Literature 1). In addition, with respect to scan welding of the laser, a method in which the laser is scanned on the surface of the workpiece in a manner of drawing a Lissajous figure has been proposed from the past (see, for example, Patent Literature 1).

[0026] In the conventional scan welding proposed in Patent Literature 1, emphasis is placed on high-speed welding by moving the laser beam, and a large effect on improvement of productivity can be obtained. However, in an actual laser welding site, laser welding is sometimes performed in a manner in which a machining head periodically draws a prescribed pattern while moving along a curved shape, for example, a joint connecting a straight portion to a straight portion. In such a case, unevenness (in other words, imbalance) of the amount of heat input of the laser (laser beam) to the workpiece occurs inside and outside the prescribed pattern along with movement of the curved shape portion of the machining head, and there is a problem that a good bead cannot be obtained.

[0027] Thus, in the following embodiments, an example of a laser welding apparatus and a laser welding method in which the heat input of the laser is balanced and uniform inside and outside and degradation of the quality of a bead is suppressed in laser welding along a welding line having a curved shape will be described.

[0028] Hereinafter, embodiments of the laser welding apparatus and the laser welding method of the present application will be described in detail with appropriate reference to the accompanying drawings. However, there are cases in which detailed description necessary or more is omitted. For example, there are cases in which detailed description of matters already known and repeated description of substantially the same structure are omitted. This is in order to avoid the following description from becoming unnecessarily lengthy and to make it easy for those skilled in the art to understand. Note that the drawings and the following description are provided in order for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the patent technical solution by these.

[0029] (Embodiment 1)

[0030] 1. Structure of laser welding device

[0031] Figure 1 is a view showing a schematic configuration example of a laser welding device 100 of the present embodiment. The laser welding device 100 is a structure including a laser oscillator 10, an optical fiber 20, a galvanometer head 30 provided with a galvanometer scanner 40, a controller 50, and a robot 60. Note that a display DP1 can be connected to the controller 50 in a manner that enables display of various data (e.g., screen data, etc.) from the controller 50.

[0032] In the following description, there are cases where a direction parallel to a traveling direction of the laser LB toward the galvanometer scanner 40 from the mirror 33 is referred to as an X direction, a direction parallel to an optical axis of the laser LB emitted from the galvanometer head 30 is referred to as a Z direction, and a direction orthogonal to the X direction and the Z direction, respectively, is referred to as a Y direction. An XY plane including the X direction and the Y direction in-plane can be substantially parallel to a surface of the workpiece 200 in a case where the surface of the workpiece 200 is a flat surface, or can be at an angle to the surface of the workpiece 200.

[0033] The laser oscillator 10 is a laser source that generates the laser LB by being supplied with electric power from a laser driving power source (omitted from the drawing). The laser oscillator 10 can be constituted by a single laser source, or can be constituted by a plurality of laser modules.

[0034] The laser source or the laser module used in the laser oscillator 10 is appropriately selected depending on a material of the workpiece 200 as a welded object or a shape of a welding site, etc. For example, a fiber laser, a disc laser, or a Yttrium Aluminum Garnet (YAG) laser can be provided as the laser source. In this case, the wavelength of the laser LB is set to a range of 1000 [nm] to 1100 [nm]. In addition, a semiconductor laser can be provided as the laser source or the laser module. In this case, the wavelength of the laser LB is set to a range of 800 [nm] to 1000 [nm]. In addition, a visible laser can be provided as the laser source or the laser module. In this case, the wavelength of the laser LB is set to a range of a blue band of 420 [nm] to 500 [nm], or a green band of 480 [nm] to 560 [nm].

[0035] One end side (incident end) of the optical fiber 20 is optically coupled with the laser oscillator 10, and the other end side (emergent end) of the optical fiber 20 is optically coupled with the galvanometer head 30. The optical fiber 20 has a core (not shown) in the center thereof, and a cladding (not shown) is provided in contact with the outer peripheral surface of the core and coaxially with the core. The core and the cladding each have quartz as a main component, and the core has a higher refractive index than the cladding. Therefore, the laser LB generated by the laser oscillator 10 is incident on the incident end of the optical fiber 20, and is transmitted inside the core while repeatedly reflecting and the like toward the emergent end. In addition, a skin film (not shown) or a resin-based protective layer (not shown) that mechanically protects the optical fiber 20 is provided on the outer peripheral surface of the cladding.

[0036] The galvanometer head 30 is mounted to the emergent end of the optical fiber 20, and at least a collimator lens 32 (one example of an optical member), a mirror 33 (one example of an optical member), a condenser lens 34 (one example of an optical member), and a galvanometer scanner 40 (one example of an optical member) are housed in a housing 31. These optical members are housed inside the housing 31 in a manner that a prescribed arrangement relationship is maintained. Regarding a structure example of the galvanometer scanner 40, refer to Figure 2 which will be described in detail.

[0037] The galvanometer head 30 temporarily collimates the laser (in other words, the laser beam) transmitted and expanded via the optical fiber 20 into parallel light, then reflects the collimated parallel light using the mirror 33, and condenses the light using the condenser lens 34. Furthermore, the galvanometer head 30 irradiates the laser condensed by the condenser lens 34 toward the welding point of the surface of the workpiece 200 by two-dimensionally scanning using the galvanometer scanner 40 in a manner that a prescribed pattern (refer to later) is periodically drawn while along the desired welding line. Thus, the workpiece 200 can be welded by laser welding. The two-dimensional scanning of the laser LB by the galvanometer scanner 40 in the galvanometer head 30 is controlled by controlling the drivers (not shown) of the X-axis mirror (refer to later) and the Y-axis mirror (refer to later) of the galvanometer scanner 40 using the controller 50.

[0038] When the laser LB emerging from the optical fiber 20 is incident, the collimator lens 32 converts it into parallel light and makes it incident on the mirror 33. The collimator lens 32 can be coupled with a driving portion (not shown) and configured to be able to displace in the Z direction according to a control signal from the controller 50. By displacing the collimator lens 32 in the Z direction, the focal position of the laser LB can be changed and the laser LB can be appropriately irradiated according to the shape of the workpiece 200. That is, the collimator lens 32 also functions as a focal position adjustment mechanism of the laser LB by the combination with the driving portion (not shown). Note that the condenser lens 34 can also be displaced by the driving portion, thereby changing the focal position of the laser LB.

[0039] The mirror 33 reflects the laser light LB that has passed through the collimator lens 32, and causes it to pass through the condenser lens 34 to be incident on the galvanometer scanner 40. The surface of the mirror 33 is disposed at about 45 degrees to the optical axis of the laser light LB that has passed through the collimator lens 32.

[0040] The condenser lens 34 condenses the laser light LB that has been reflected by the mirror 33 and scanned by the galvanometer scanner 40 on the surface of the workpiece 200. In the illustration, the condenser lens 34 is disposed in front of the galvanometer scanner 40 (the collimator lens 32 side), but it is also possible to dispose the condenser lens 34 behind the galvanometer scanner 40 (the workpiece 200 side).

[0041] The controller 50 is structured with a control section 51 constituted by a processor or the like, and a memory 52 constituted by a memory or the like. The controller 50 controls the timing, output, start, end, and the like of laser oscillation of the laser oscillator 10. Specifically, the controller 50 controls laser oscillation and laser output in the control section 51 by supplying an output current and an on-off time or the like control signal to a laser drive power supply (omitted from the illustration) connected to the laser oscillator 10. In addition, the controller 50 controls the irradiation position of the laser light irradiated by the galvanometer head 30 in accordance with the contents of a machining program for performing laser welding (machining) of the workpiece 200 saved in the memory 52. In addition, the controller 50 generates a command signal for controlling the movement of the robot hand 60 and transmits it to the robot hand 60.

[0042] The memory 52 stores a machining program for laser welding. The memory 52 can be disposed inside the controller 50 as shown in Figure 1 , or can be disposed outside the controller 50 and structured so as to be able to interact with the controller 50 in data.

[0043] The robot hand 60 is, for example, a publicly known vertical 6-axis robot having 6 joint axes. The 6th joint axis is disposed at the front end of a robot arm possessed by the robot hand 60. The robot hand 60 is able to grip the galvanometer head 30 by means of a gripping member (omitted from the illustration) from the 6th joint axis, and control the position of the galvanometer head 30 to be movable in accordance with a command signal from the controller 50.

[0044] The display DP1 is constituted using, for example, a Liquid Crystal Display (LCD) or an organic Electroluminescence (EL) display, and is connected so as to be able to input and output a data signal between the controller 50. The display DP1 displays a screen (for example, a message indicating the start, interruption, re-start, end of laser welding (machining)) indicating the processing result by the control section 51.

[0045] Here, reference is made to Figure 2The structure and operation of the galvanometer scanner 40 housed within the galvanometer 30 will be explained. Figure 2 This is a schematic diagram illustrating an example of the structure of the vibrating lens 30.

[0046] like Figure 2 As shown, the galvanometer scanner 40 is a known laser scanner having a first galvanometer reflector 41 (also called an X-axis reflector) and a second galvanometer reflector 42 (also called a Y-axis reflector). The first galvanometer reflector 41 has a first reflector 41a, a first rotation axis 41b, and a first drive unit 41c. The second galvanometer reflector 42 has a second reflector 42a, a second rotation axis 42b, and a second drive unit 42c. The laser LB, which has passed through the condenser lens 34, is reflected by the first reflector 41a and then by the second reflector 42a, and thus illuminates the surface of the workpiece 200.

[0047] For example, the first drive unit 41c and the second drive unit 42c are galvanometer motors. The first rotating shaft 41b and the second rotating shaft 42b are the output shafts of the motors. Although not shown, the first drive unit 41c is driven to rotate by a driver that operates according to a control signal from the controller 50, thereby causing the first reflector 41a mounted on the first rotating shaft 41b to rotate about the axis of the first rotating shaft 41b. Similarly, the second drive unit 42c is driven to rotate by a driver that operates according to a control signal from the controller 50, thereby causing the second reflector 42a mounted on the second rotating shaft 42b to rotate about the axis of the second rotating shaft 42b.

[0048] The first reflector 41a rotates about the axis of the first rotation axis 41b to a predetermined angle, thereby scanning the laser LB along the X direction. Meanwhile, the second reflector 42a rotates about the axis of the second rotation axis 42b to a predetermined angle, thereby scanning the laser LB along the Y direction. In other words, the galvanometer scanner 40 is configured to irradiate the workpiece 200 by scanning the laser LB two-dimensionally in the XY plane.

[0049] The controller 50 controls the laser oscillation of the laser oscillator 10. Specifically, the controller 50 controls the laser oscillation by supplying control signals such as output current and on / off time to the laser drive power supply (not shown) connected to the laser oscillator 10. In addition, the controller 50 controls the output of the laser LB.

[0050] Furthermore, the controller 50 controls the movement of the galvanometer scanner 40 according to the selected machining program. Specifically, the controller 50 drives the drive units (not shown) of the galvanometer scanner 40 and the collimating lens 32 installed on the galvanometer scanner 30. Moreover, the controller 50 controls the movement of the robot arm 60. It should be noted that the machining program is stored in a storage unit (not shown) located inside the controller 50 or elsewhere, and is retrieved from the controller 50 via commands.

[0051] The controller 50 has an integrated circuit such as an LSI or a microcomputer (not shown), and performs the aforementioned functions by executing a processing program as software on the integrated circuit. It should be noted that the controller 50 for controlling the operation of the scanning head 30 and the controller 50 for controlling the output of the laser LB can also be provided separately.

[0052] The robotic arm 60 is a multi-joint robot and is housed in a housing 31 for mounting the gaiter 30. Furthermore, the robotic arm 60 is connected to the controller 50 in a manner capable of signal transmission and reception, and moves the gaiter 30 in a manner that follows a predetermined trajectory according to the aforementioned processing procedure.

[0053] 2. Lissajous figures

[0054] Next, refer to Figure 3 The prescribed pattern for the scanning pattern periodically drawn by the scanning lens 30 along the welding line WL will be described. The prescribed pattern for the scanning pattern is, for example, a figure-eight or infinity-shaped Lissajous figure. Figure 3 This is a diagram illustrating an example of a Lissajous figure as a scanning pattern of a laser. In the diagram, the weld line WL is aligned with the X-axis.

[0055] exist Figure 3 In the XY plane, in this case, the laser LB scans in a manner that draws a scanning pattern SP on the surface of the workpiece 200. Figure 3 The width of the scanned pattern SP in the X direction is approximately equal to the width in the Y direction. It should be noted that in this specification, "approximately equal" or "approximately the same" means that the control results of the controlled objects are the same or identical, including errors in the control system; it does not strictly require that the two objects being compared are identical or identical. Furthermore, "approximately equal" or "approximately the same" is also used to mean that the manufacturing tolerances or assembly tolerances of the various components are the same or identical.

[0056] Figure 3The illustrated scan pattern SP is a Lissajous pattern LJ0 obtained by causing the laser LB to vibrate in a sinusoidal wave in the X direction at a prescribed frequency and in a sinusoidal wave in the Y direction at a different frequency from that in the X direction. The origin Ol of the scan pattern SP corresponds to the center point of the Lissajous pattern LJ0. Figure 3 The illustrated scan pattern SP is obtained by scanning the laser LB in the direction of the arrow AR1 during one cycle from the origin Ol to Figure 3 The illustrated scan pattern SP is obtained by scanning the laser LB in the direction of the arrow AR1 during one cycle from the origin Ol to Figure 3 The illustrated scan pattern SP is obtained by scanning the laser LB in the direction of the arrow AR2. In this case, the Lissajous pattern LJ0 has, as one cycle, a scan pattern in the shape of an 8 from the origin Ol to the point C to the point B to the point A to the origin Ol to the point F to the point E to the point D to the origin Ol.

[0057] In addition, as described above, the scan pattern of the laser LB in the X direction and the Y direction is determined based on the respective rotational motions of the first mirror 41a and the second mirror 42a. Generally, the scan pattern of the laser LB in the X direction obtained by driving the first mirror 41a is a scan pattern in the shape of a straight line extending in the X direction, and the scan pattern of the laser LB in the Y direction obtained by driving the second mirror 42a is a scan pattern in the shape of a straight line extending in the Y direction. Figure 3 The illustrated position coordinates of the scan pattern SP are set to X, and the position coordinates of the scan pattern SP obtained by driving the second mirror 42a are set to Y. Figure 3 The illustrated position coordinates of the scan pattern SP are set to X, and the position coordinates of the scan pattern SP obtained by driving the second mirror 42a are set to Y.

[0058] X = -a0 x sin (2ωt) = -a0 x sin (2 x 2πft)

[0059] = -a0 x sin (2 x 2πt / T) (1)

[0060] Y = -a0 x sin (ωt) = -a0 x sin (2πft)

[0061] = -a0 x sin (2πt / T) (2)

[0062] Here,

[0063] a0: Figure 3 The illustrated scan pattern SP1 has amplitudes in the X direction and the Y direction

[0064] ω: angular velocity

[0065] f: frequency

[0066] T: period (= 1 / f)

[0067] t: time.

[0068] Note that the position coordinates X, Y shown in the formulas (1), (2) are represented by a stationary coordinate system of the scan pattern SP in a state where the position of the galvanometer head 30 is fixed. In addition, the frequency f corresponds to the driving frequency of the first mirror 41a and the second mirror 42a, respectively. Figure 3 The scan pattern SP shown is a figure-8-shaped Lissajous pattern corresponding to the case where a0 = 1 is assumed in the formulas (1), (2). Hereinafter, the length of the Lissajous pattern LJ0 is defined as the length of the straight line connecting the points A and C, or the length of the straight line connecting the points D and F. In the formulas (1) and (2), the same amplitude a0 is used in both the X direction and the Y direction, but different amplitudes can be set for the X direction and the Y direction.

[0069] 3. Overlap ratio of each of the inner side and the outer side at the time of laser welding of the straight portion

[0070] Next, the overlap ratio of each of the inner side and the outer side in the case where the welding line WL has a straight portion and the galvanometer head 30 periodically traces a Lissajous pattern along the straight portion in laser welding in the present embodiment will be described with reference to Figure 4 , FIG. 8. Figure 4 is a graph showing the overlap ratio of the welding line upper portion IN1 and the welding line lower portion OUT1 at the time of straight welding.

[0071] As shown in Figure 4 , the welding line WL of the laser welding of the workpiece 200 performed by the laser welding apparatus 100 has straight portion intervals (see Figure 7 , the straight portions LN1, LN2). In the description of Figure 4 , the galvanometer head 30 two-dimensionally scans the laser LB while being moved in the welding direction WD along the welding line WL by the robot 60, and irradiates the workpiece 200 in a manner of periodically tracing a Lissajous pattern LJ1. In addition, in order to make the description of Figure 4 easy to understand, the region of the welding line upper portion IN1 (for example, the paper upper portion of Figure 4 ) as one side of the welding line WL is defined as the region of the inner side of the welding line WL, and the region of the welding line lower portion OUT1 (for example, the paper lower portion of Figure 4 ) as the other side of the welding line WL is defined as the region of the outer side of the welding line WL.

[0072] As described above, the Lissajous pattern LJ0 shown in Figure 3 is a scan pattern when the galvanometer head 30 traces while not advancing along the welding line WL (i.e., in a stationary state). That is, in one period amount of the Lissajous pattern LJ0, the start position and the end position are the same, and for example, become the origin O1.

[0073] However, when the galvanometer head 30 periodically traces the Lissajous figure while advancing along the straight line section of the welding line WL in the welding direction WD, the Lissajous figure LJ1 shown is traced. Figure 4 The Lissajous figure LJ1 is a structure in which a substantially 8-shaped figure connected by the points G0→G1→G2→G3→G4→G5→G6→G7→G8 is one cycle, and has a plurality of one cycle amounts. In this case, in one cycle amount of the Lissajous figure LJ1, the start position (i.e., the position of the point G0) and the end position (i.e., the position of the point G8) are different. The distance between the point G0 and the point G8 corresponds to the moving distance of the galvanometer head 30 in one cycle during the Lissajous figure LJ1 is traced in the welding direction WD along the welding line WL. Note that, in the Lissajous figure LJ1, the length of the Lissajous figure in the inside is represented by "L4" in the case of three cycle amounts. Figure 4

[0074] The length of the Lissajous figure in the inside of the Lissajous figure LJ1 becomes, for example, the length of the straight line connecting the points G1 and G3 of the Lissajous figure of the first cycle, and similarly, the length of the straight line connecting the points G9 and G11 of the Lissajous figure of the second cycle, and in the case of three cycle amounts, is represented by "L3". Figure 4 In addition, in the Lissajous figure LJ1 of three cycle amounts, the length of the Lissajous figure in the inside (welding line upper portion IN1) of the first cycle that overlaps with the Lissajous figure in the inside (welding line upper portion IN1) of the second cycle becomes the length of the straight line connecting the point G3 of the first cycle and the point G9 of the second cycle, and in the case of three cycle amounts, is represented by "L3". Figure 4

[0075] That is, in the straight line section of the welding line WL, when the overlap rate of the Lissajous figure in the inside (welding line upper portion IN1) is defined as a2, a2=L3 / L4 is calculated.

[0076] Similarly, the length of the Lissajous figure in the outside of the Lissajous figure LJ1 becomes, for example, the length of the straight line connecting the points G5 and G7 of the Lissajous figure of the first cycle, and similarly, the length of the straight line connecting the points G13 and G15 of the Lissajous figure of the second cycle, and in the case of three cycle amounts, is represented by "L2". Figure 4 In addition, in the Lissajous figure LJ1 of three cycle amounts, the length of the Lissajous figure in the outside (welding line lower portion OUT1) of the first cycle that overlaps with the Lissajous figure in the outside (welding line lower portion OUT1) of the second cycle becomes the length of the straight line connecting the point G7 of the first cycle and the point G13 of the second cycle, and in the case of three cycle amounts, is represented by "L1". Figure 4

[0077] ​​​That is, in the straight line section of the welding line WL, when the overlap ratio of the Lissajous figure of the outer side (lower part OUT1 of the welding line) is defined as a1, it is calculated as a1=L1 / L2.

[0078] In the straight line section of the welding line WL, the Lissajous figure of the inner side is symmetrical with the Lissajous figure of the outer side with the welding line WL sandwiched therebetween. Therefore, it becomes L1=L3, L2=L4. That is, it becomes overlap ratio a1=overlap ratio a2.

[0079] Therefore, the control section 51 calculates the position X, Y of the irradiation of the laser LB from the galvanometer head 30 using the equations (3), (4) respectively in the straight line section of the welding line WL, and calculates the overlap ratios a1, a2 using the equations (5), (6) respectively. The relationship of a1=a2 can be observed from the equation (5) and the equation (6). Further, it is known that if the welding speed v is not 0, the overlap ratios a1 and a2 always become 1 or less. The control section 51 controls the two-dimensional scanning of the laser LB using the calculation results of the mathematical equations (3) and (4). As a result thereof, the results of the mathematical equations (5), (6) are obtained. The various parameters are, for example, the three of a0, f, v. The equation (4) is the same as the equation (2) described above.

[0080] X=vt-a0×sin(2·2πft)

[0081] =vt-a0×sin(2·2πt / T) (3)

[0082] Y=-a0×sin(2πft)

[0083] =-a0×sin(2πt / T) (4)

[0084] Here,

[0085] a0: Figure 5 Amplitude in the X direction, Y direction of the Lissajous figure LJ1

[0086] ω: Angular velocity

[0087] f: Frequency

[0088] T: Period

[0089] v: Moving speed of the center of the Lissajous figure in the welding direction WD (in other words, welding speed)

[0090] t: Time.

[0091] a1=L1 / L2

[0092] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0093] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0094] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0095] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0096] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0097] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0098] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0099] = ((X coordinate of point G7 at (7 / 8) period - X coordinate of point G13 at (13 / 8) period)) / ((X coordinate of point G15 at (15 / 8) period - X coordinate of point G13 at (13 / 8) period))

[0100] 4. Problem in laser welding of curved portion: imbalance in heat input from inside and outside of laser

[0101] Next, referring to Figure 5 , the problem in the case of laser welding in which the welding line WL has a curved portion and the conventional galvanometer head traces a Lissajous figure along the curved portion periodically will be described. Figure 5 is a graph showing the overlap ratio of the upper welding line portion and the lower welding line portion of the welding line in the case of curved welding. In the explanation of Figure 4 , also similarly to the explanation of Figure 5 , the upper welding line portion IN2 (for example, the portion indicated by the reference numeral 2 in FIG. 1) on one side of the welding line WL will be described. Figure 5the area of the paper upper portion) is defined as the area on the inner side of the welding line WL, and the area of the paper lower portion) is defined as the area on the outer side of the welding line WL. Figure 5 the area of the paper lower portion) is defined as the area on the outer side of the welding line WL.

[0102] Figure 5 The welding line WL illustrated in FIG. 6 has a curved portion with a radius of curvature R. When the galvanometer head traces the welding line WL along the curved portion interval while periodically drawing a Lissajous figure, the Lissajous figure LJ2 illustrated in FIG. 7 is drawn. Figure 5 The Lissajous figure LJ2 is a structure in which a substantially 8-shaped figure connected by the points H0→H1→H2→H3→H4→H5→H6→H7→H8 is one cycle, and has a plurality of one-cycle amounts. In this case, in the Lissajous figure LJ2 of one cycle amount, the start position (i.e., the position of the point H0) is different from the end position (i.e., the position of the point H8). Note that, in the Lissajous figure LJ2, for example, three cycle amounts of the Lissajous figure LJ2 are illustrated. Figure 5

[0103] The length of the Lissajous figure on the inner side in the Lissajous figure LJ2 becomes, for example, the length of the circular arc connected by the points H9 and H11 of the second cycle (and the circular arc of the curved portion of the welding line WL with the same radius of curvature R is concentric. Hereinafter, L5 to L7 and L9 to L12 are also similarly circular arcs, and thus the description is omitted). In the Lissajous figure LJ2, this is indicated by "L8". Figure 5 In the Lissajous figure LJ2 of three cycle amounts, the length of the Lissajous figure on the inner side (the welding line upper portion IN2) of the first cycle that overlaps the Lissajous figure on the inner side (the welding line upper portion IN2) of the second cycle that follows becomes the length of the circular arc of the curved portion (refer to the above) of the welding line WL with the same radius of curvature R connected by the point H3 of the first cycle and the point H9 of the second cycle. In the Lissajous figure LJ2, this is indicated by "L7". Figure 5

[0104] That is, in the curved portion interval of the welding line WL, when the overlap rate of the Lissajous figure on the inner side (the welding line upper portion IN2) is defined as a4, a4 = L7 / L8 is calculated.

[0105] Similarly, the length of the Lissajous figure on the outer side in the Lissajous figure LJ2 becomes, for example, the length of the circular arc of the curved portion (refer to the above) of the welding line WL with the same radius of curvature R connected by the points H13 and H15 of the second cycle, in the Lissajous figure LJ2. Figure 5 ​​In the middle, it is indicated by "L6". In addition, in the 3-cycle Lissajous figure LJ2, the length in which the Lissajous figure of the outer side (weld line lower portion OUT2) of the first cycle overlaps with the Lissajous figure of the outer side (weld line lower portion OUT2) of the second cycle becomes the length of the circular arc of the same curvature radius R as the weld line WL (refer to the above) which connects the point H7 of the first cycle and the point H13 of the second cycle, and in the 3-cycle Lissajous figure LJ3, the length in which the Lissajous figure of the outer side (weld line lower portion OUT2) of the first cycle overlaps with the Lissajous figure of the outer side (weld line lower portion OUT2) of the second cycle becomes the length of the circular arc of the same curvature radius R as the weld line WL (refer to the above) which connects the point H7 of the first cycle and the point H13 of the second cycle. Figure 5 In the middle, it is indicated by "L5".

[0106] That is, in the curved portion interval of the weld line WL, when the overlap ratio of the Lissajous figure of the outer side (weld line lower portion OUT2) is defined as a3, it is calculated as a3 = L5 / L6.

[0107] In the curved portion interval of the weld line WL, since the curvature radius R exists, the Lissajous figure of the inner side and the Lissajous figure of the outer side sandwich the weld line WL and become asymmetric. More specifically, it becomes L5 < L1, L6 > L2, L7 > L3, L8 < L4. That is, the overlap ratio also becomes a3 < a1, a4 > a2, and becomes a3 ≠ a4. Therefore, in the case of performing laser welding in which the weld line WL has a curved portion, and the oscillating mirror head periodically draws a Lissajous figure along the curved portion, since the curvature radius R exists, the overlap ratio of the Lissajous figure of the inner side and the overlap ratio of the Lissajous figure of the outer side are not consistent. Therefore, in the case of performing laser welding in which the weld line WL has a curved portion, and the oscillating mirror head periodically draws a Lissajous figure along the curved portion, since the curvature radius R exists, the overlap ratio of the Lissajous figure of the inner side and the overlap ratio of the Lissajous figure of the outer side are not consistent. Therefore, in the case of performing laser welding in which the weld line WL has a curved portion, and the oscillating mirror head periodically draws a Lissajous figure along the curved portion, the heat input amount of the laser (laser beam) irradiated from the oscillating mirror head to the workpiece becomes uneven (in other words, unbalanced) in some cases. Figure 6 In the relationship of the arc lengths of L5, L6, L7, and L8 shown in the drawing, sometimes, the heat input amount of the laser (laser beam) irradiated from the oscillating mirror head to the workpiece becomes uneven (in other words, unbalanced). In other words, there is a problem that a good weld bead cannot be obtained by laser welding.

[0108] 5. Overlap ratio of each of the inner side and the outer side at the time of laser welding of the curved portion

[0109] Next, the control method of the overlap ratio of each of the inner side and the outer side in the case where laser welding is performed in which the weld line WL has a curved portion, and the oscillating mirror head 30 periodically draws a Lissajous figure along the curved portion in the present embodiment will be described with reference to Figure 6 Figure 6 is a drawing which shows the overlap ratio of the weld line upper portion IN2 and the weld line lower portion OUT2 of the present embodiment at the time of curved welding. In the explanation of Figure 4 , also similarly to the explanation of Figure 5 or Figure 6 , the region of the weld line upper portion IN2 (for example, the paper upper portion of Figure 6 ) which is one side of the weld line WL is defined as the region of the inner side of the weld line WL, and the region of the weld line lower portion OUT2 (for example, the paper lower portion of Figure 6 ) which is the other side of the weld line WL is defined as the region of the outer side of the weld line WL.​

[0110] Figure 6 The weld line WL shown has a curved portion with a radius of curvature R. In the present embodiment, when the galvanometer head 30 periodically traces a Lissajous figure while advancing along the curved portion section of the weld line WL in the welding direction WD, the Lissajous figure LJ3 shown is traced. Figure 6 The Lissajous figure LJ3 shown is a figure having a structure in which a substantially 8-shaped figure connected by the points J0→J1→J2→J3→J4→J5→J6→J7→J8 is one cycle, and a plurality of one cycle amounts. In this case, in one cycle amount of the Lissajous figure LJ3, the start position (i.e., the position of the point J0) and the end position (i.e., the position of the point J8) are different. Note that, in the present embodiment, for example, a Lissajous figure LJ3 of 3 cycle amounts is shown. Figure 6

[0111] The length of the Lissajous figure on the inside in the Lissajous figure LJ3 becomes, for example, the length of the circular arc of the curved portion (refer to the above) with the same radius of curvature R as the weld line WL, which connects the points J9 and J11 of the second cycle Lissajous figure, in Figure 6 which is represented by "L12". Also, in the Lissajous figure LJ3 of 3 cycle amounts, the length of the Lissajous figure on the inside (weld line upper portion IN2) of the first cycle that overlaps with the Lissajous figure on the inside (weld line upper portion IN2) of the second cycle that follows becomes the length of the circular arc of the curved portion (refer to the above) with the same radius of curvature R as the weld line WL, which connects the point J3 of the first cycle and the point J9 of the second cycle, in Figure 6 which is represented by "L11".

[0112] That is, in the curved portion section of the weld line WL of the present embodiment shown in Figure 6 , when the overlap rate of the Lissajous figure on the inside (weld line upper portion IN2) is defined as a6, a6 = L11 / L12 is calculated.

[0113] Likewise, the length of the Lissajous figure on the outside in the Lissajous figure LJ3 becomes, for example, the length of the circular arc of the curved portion (refer to the above) with the same radius of curvature R as the weld line WL, which connects the points J13 and J15 of the second cycle Lissajous figure, in Figure 6 which is represented by "L10". Also, in the Lissajous figure LJ3 of 3 cycle amounts, the length of the Lissajous figure on the outside (weld line lower portion OUT2) of the first cycle that overlaps with the Lissajous figure on the outside (weld line lower portion OUT2) of the second cycle that follows becomes the length of the circular arc of the curved portion (refer to the above) with the same radius of curvature R as the weld line WL, which connects the point J7 of the first cycle and the point J13 of the second cycle, in Figure 6 ​indicated by "L9".

[0114] That is, in the curved portion interval of the welding line WL of the present embodiment, when the overlap ratio of the Lissajous figure of the outer side (welding line lower portion OUT2) is defined as a5, it is calculated as a5 = L9 / L10. Figure 7

[0115] That is, in the present embodiment, the control section 51 of the laser welding device 100 controls L9 and L10, or Ll l and L12, or both, in such a manner that the overlap ratio of the Lissajous figure has a relationship of a5 = a6, in accordance with the magnitude of the radius of curvature R of the curved portion of the welding line WL. Thereby, the overlap ratio of the Lissajous figure of the inner side (a5) in the curved portion interval of the welding line WL and the overlap ratio of the Lissajous figure of the outer side (a6) in the curved portion interval satisfy an equal relationship. Therefore, the laser welding device 100 does not generate unevenness (in other words, imbalance) of the amount of heat input of the laser LB irradiated from the galvanometer head 30 to the workpiece 200, and can obtain a good bead in the workpiece 200.

[0116] In addition, the control section 51 of the laser welding device 100 controls L9 and L10, or Ll l and L12, or both, in such a manner that the overlap ratio of the Lissajous figure has a relationship of a5 = a6 = a1 = a2, in accordance with the magnitude of the radius of curvature R of the curved portion, in the case where a straight portion and a curved portion exist mixed in the welding line WL. That is, the control section 51 controls the two-dimensional scanning of the laser LB in such a manner that the overlap ratio of the Lissajous figure of either the inner side or the outer side of the welding line WL is equal, in the case where the welding line WL has a straight portion and a curved portion (refer to Figure 6 ). Thereby, the laser welding device 100 does not generate unevenness (in other words, imbalance) of the amount of heat input of the laser LB irradiated from the galvanometer head 30 to the workpiece 200, on either the inner side or the outer side of the welding line WL, even in the case where the welding line WL has not only a curved portion but also a straight portion, and does not generate unevenness in the straight portion and the curved portion, and thus can obtain a good bead without deviation in the inner side and the outer side, the straight portion, and the curved portion, respectively, in the entire range of the welding line WL of the workpiece 200.

[0117] The control section 51 controls the two-dimensional scanning of the laser LB in such a manner that the overlap ratio of the Lissajous figure of either the inner side or the outer side of the welding line WL is equal, in the case where the welding line WL has a straight portion and a curved portion (refer to Figure 6 ​In the above-described equation (7), (8), the position X, Y at which the laser LB from the galvanometer head 30 is irradiated is calculated using the equations (7), (8), respectively. However, in the equations (7), (8), the amplitude a(R, c) determined in association with the radius of curvature R of the curved portion of the welding line WL and whether the inside or the outside of the curved portion of the welding line WL is required to be used. This amplitude a(R, c) is required to be calculated through a complicated calculation on the basis that the circular arcs L9 to L12 are calculated as described above and set to the overlapping ratios a5=a6 (a5=a6=a1=a2 in the case where the straight line portions exist). Here, the complicated calculation equation cannot be described, but a value calculated in advance through numerical calculation can be used. The control section 51 controls the two-dimensional scanning of the laser LB using this calculation result. Various parameters such as the four of a0, a(R, c), f, and v. The equation (8) is the same as the equation (4) described above.

[0118] X = vt - a(R, c) x sin(2 x 2πft)

[0119] = vt - a(R, c) x sin(2 x 2πt / T)...(7)

[0120] Y = -a0 x sin(2πft)

[0121] = -a0 x sin(2πt / T)...(8)

[0122] Here,

[0123] a0: Figure 7 amplitude of the Lissajous figure LJ3 in the Y direction

[0124] a(R, c): amplitude of the Lissajous figure LJ3 in the X direction as a function of the radius of curvature R of the welding line WL and the parameter c indicating which side of the inside and the outside of the curved portion of the welding line WL

[0125] f: frequency

[0126] T: period

[0127] v: moving speed of the center of the Lissajous figure in the welding direction WD (in other words, welding speed)

[0128] t: time.

[0129] 6. Action sequence of laser welding

[0130] Next, the action sequence of the laser welding performed by the laser welding apparatus 100 of the present embodiment will be described with reference to Figure 8 and Figure 8 Figure 8 is a view showing an example of the laser welding pattern of the present embodiment. Figure 7 ​is a flowchart showing an example of the operation sequence of the laser welding of the laser welding apparatus 100 according to the present embodiment in time series. Figure 7 The various processes shown are mainly executed by the control section 51 of the controller 50 while cooperating with the memory 52.

[0131] Figure 4 The laser welding pattern shown is a pattern obtained by periodically drawing Lissajous patterns while moving the galvanometer head 30 along the welding line WL having straight line portions LN1, LN2,... and curved line portions CV1, CV2,... and performing two-dimensional scanning of the laser LB by the galvanometer head 30.

[0132] In the laser welding pattern shown in Figure 6 In the laser welding pattern shown in Figure 8 The Lissajous pattern drawn in each of the straight line portions LN1, LN2,... corresponds to the Lissajous pattern LJ1 shown in Figure 8 The Lissajous pattern drawn in each of the straight line portions LN1, LN2,... corresponds to the Lissajous pattern LJ1 shown in

[0133] In the laser welding pattern shown in Figure 7 In the laser welding pattern shown in

[0134] The control section 51 sets the respective overlap ratios of the inner side and the outer side in the entire straight line portion interval (for example, the entire length of the straight line portion LN1) (step St3) in the case where it is determined that the current position is a straight line portion (step St2, Yes). Also, the control section 51 sets various parameters of the Lissajous pattern drawn by the galvanometer head 30 (for example, the amplitudes a0 in the X direction and the Y direction, the frequency f, and the moving speed (welding speed) v of the center of the Lissajous pattern in the welding direction WD) (step St3). As for the processing of step St3, the result calculated in real time each time can be used as the set value, or the result calculated in advance based on the shape of the welding line WL and the Lissajous pattern can be used as the set value read from a database (for example, the memory 52).

[0135] The control section 51 performs welding on the workpiece 200 using the set values set in step St3 (i.e., irradiating the laser LB while two-dimensionally scanning) (step St4). After the welding in this step St4 ends, it is determined whether or not the entire welding ends (step St5). In a case where it is determined that the current position is not the end point of the welding (step St5, No), the processing of the control section 51 returns to step St2.

[0136] On the other hand, in a case where it is determined that the current position is a curved portion (step St2, No), the control section 51 sets the overlap rates of the inner side and the outer side in the entire curved portion interval (e.g., the entire length of the curved portion CV1) (step St6). Also, the control section 51 sets various parameters of the Lissajous figure drawn by the galvanometer head 30 (e.g., the amplitude a0 in the Y direction of the Lissajous figure, the amplitude a (R, c) in the X direction of the Lissajous figure LJ3 which is a function of the radius of curvature R of the welding line WL and a parameter c indicating which of the inner side and the outer side of the curved portion is the welding line WL, the frequency f, the moving speed (welding speed) v of the center of the Lissajous figure in the welding direction WD) (step St6). As for the processing of step St6, results calculated in advance based on the shape of the welding line WL and the Lissajous figure are used as set values read from a database (e.g., the memory 52).

[0137] The control section 51 performs welding on the workpiece 200 using the set values set in step St6 (i.e., irradiating the laser LB while two-dimensionally scanning) (step St7). After the welding in this step St7 ends, it is determined whether or not the entire welding ends (step St8). In a case where it is determined that the current position is not the end point of the welding (step St8, No), the processing of the control section 51 returns to step St2. The welding is performed by repeating the above steps, but in a case where it is determined by the control section 51 that the welding ends (step St5, Yes, or step St8, Yes), Figure 7 the processing of the control section 51 shown in FIG. 8 ends.

[0138] Note that, in Figure 9A , a figure obtained by periodically drawing a Lissajous figure using two-dimensional scanning of the laser LB by the galvanometer head 30 while moving the galvanometer head 30 along the welding line WL is exemplified. However, the laser welding figure of the laser welding apparatus 100 of the present embodiment is of course not limited to the Lissajous figure as shown in Figure 9B . For example, it can be a figure as shown in Figure 9C , Figure 9A and Figure 9B each shape.

[0139] Figure 9Cis a drawing showing an example of a pattern of the first modification example. Figure 9A is a drawing showing an example of a pattern of the second modification example. Figure 9B is a drawing showing an example of a pattern of the third modification example.

[0140] As shown in Figure 9B , it can also be a combined pattern of two circular patterns arranged in contact with each other with the Y axis sandwiched at the origin O1.

[0141] As shown in Figure 9C , it can also be a combined pattern of two elliptical patterns arranged in contact with each other with the Y axis sandwiched at the origin O1. In the example shown in Figure 9A - Figure 9C , in each of the two elliptical patterns, the major axis is in the Y direction and the minor axis is in the X direction. However, it can also be that the major axis is in the X direction and the minor axis is in the Y direction.

[0142] As shown in Figure 6 , it can also be a combined pattern of two diamond patterns arranged in contact with each other with the Y axis sandwiched at the origin O1. Note that the size of each of the two ring-shaped patterns can also be changed as appropriate.

[0143] That is, the scan pattern (an example of a prescribed pattern) of the laser LB in the first to third modification examples is a pattern in which two ring-shaped patterns are in contact with each other at the origin O1, and is not limited to Figure 4 the examples shown in each of the figures, modification examples thereof. For example, in each of the scan patterns SP4, SP5, and SP6, the amplitude of the up-and-down operation can be changed so as to be asymmetric with respect to up and down. Note that these patterns are obtained by driving the first mirror 41a and the second mirror 42a respectively in accordance with a prescribed drive pattern.

[0144] <TECHNICAL IDEAS>

[0145] As explained above, in the present application, the following technical ideas are disclosed.

[0146] <TECHNICAL IDEA 1>

[0147] A laser welding device in which

[0148] The laser welding device includes:

[0149] a laser oscillator (10) that generates a laser (LB);

[0150] a machining head (galvanometer head 30) that causes the laser to be scanned two-dimensionally while traveling along a welding line (WL) having at least a curved portion (CV1, CV2,...) so as to irradiate the laser toward the surface of a workpiece (200) in a manner that periodically traces a prescribed pattern (Lissajous pattern LJ3); and

[0151] a controller (50) that controls movement of the processing head along the welding line and two-dimensional scanning of the laser,

[0152] the controller controls the two-dimensional scanning of the laser at the curved portion in such a manner that a first overlap ratio (a6) representing an overlap ratio of the pattern on one side (IN2 side) obtained based on periodic depiction of the pattern at the curved portion is identical to a second overlap ratio (a5) representing an overlap ratio of the pattern on the other side (OUT2 side) obtained based on periodic depiction of the pattern at the curved portion.

[0153] Thus, the laser welding device 100 can make the heat input balance of the laser LB irradiated from the galvanometer head 30 uniform on the inner side and the outer side, respectively, in laser welding along the welding line WL having at least a curved shape (for example, a curved portion having a radius of curvature R, with reference to Figure 6 Thus, the laser welding device 100 can suppress deterioration in quality of a weld bead formed by laser welding.

[0154] <TECHNICAL 2>

[0155] The laser welding device according to <TECHNICAL 1>, wherein

[0156] the pattern is a Lissajous pattern in a figure-8 shape or an ∞ shape,

[0157] the controller controls the two-dimensional scanning of the laser in such a manner that a center position (origin point Ol or Figure 6 、 Figure 6 a barycentric position of one cycle amount of the Lissajous pattern) of the Lissajous pattern passes through the welding line, and a start position (point J0) and an end position (point J8) of one cycle of the Lissajous pattern at the curved portion are different.

[0158] Thus, the laser welding device 100 can make the heat input balance of the laser LB irradiated from the galvanometer head 30 uniform on the inner side (IN2 side) and the outer side (OUT2 side) that sandwich the welding line WL, respectively, in laser welding that periodically depicts a Lissajous pattern while moving the galvanometer head 30 along the welding line WL.

[0159] <TECHNICAL 3>

[0160] The laser welding device according to <TECHNICAL 1> or <TECHNICAL 2>, wherein

[0161] the controller includes a memory (52) that stores one or more first parameters (for example, Figure 6one or more second parameters (e.g., L11, L12) for defining the second overlap ratio ​ L9, L10) shown.

[0162] Thus, the laser welding device 100 can perform laser welding that obtains a high-quality weld bead while suppressing an increase in the processing load of the control section 51 by using the set values stored in advance in the memory 52 without calculating the first parameter and the second parameter in real time in laser welding.

[0163] <TECHNICAL 4>

[0164] The laser welding device according to <TECHNICAL 2>, wherein

[0165] The controller calculates the first overlap ratio based on a length (L11) at which the Lissajous pattern on one side (the upper portion IN2 side of the welding line) of the mth (m: an integer of 1 or more) cycle at the curved portion overlaps with the Lissajous pattern on the same side (the upper portion IN2 side of the welding line) of the (m+1)th cycle at the curved portion and a length (L12) of one cycle amount of the Lissajous pattern,

[0166] The controller calculates the second overlap ratio based on a length (L9) at which the Lissajous pattern on the other side (the lower portion OUT2 side of the welding line) of the mth cycle at the curved portion overlaps with the Lissajous pattern on the same side (the lower portion OUT2 side of the welding line) of the (m+1)th cycle at the curved portion and a length (L10) of one cycle amount of the Lissajous pattern.

[0167] Thus, the laser welding device 100 can set the overlap ratio in such a manner that the heat input on the inner side and the heat input on the outer side of the curved portion are equal to each other, and can make the heat input on the inner side and the heat input on the outer side each uniform when laser welding is performed in such a manner that the Lissajous pattern is periodically drawn while the galvanometer head 30 is moved by the robot 60.

[0168] <TECHNICAL 5>

[0169] The laser welding device according to <TECHNICAL 2> or <TECHNICAL 4>, wherein

[0170] The welding line further has a linear portion (LN1, LN2,...),

[0171] The controller calculates a third overlap ratio (a2) that represents an overlap ratio of the Lissajous pattern on one side (the upper portion IN1 side of the welding line) based on periodic drawing of the Lissajous pattern at the linear portion,

[0172] The controller calculates a fourth overlap ratio (al) representing an overlap ratio of the Lissajous figure on the other side (OUT1 side) obtained based on periodic depiction of the Lissajous figure at the straight portion,

[0173] The controller controls the two-dimensional scanning of the laser at the curved portion in such a manner that the first overlap ratio, the second overlap ratio, the third overlap ratio, and the fourth overlap ratio are respectively identical.

[0174] Thus, the laser welding device 100 can make the heat input balance uniform on the inner side (IN2 side) and the outer side (OUT2 side) of the welding line WL respectively by the laser LB irradiated from the galvanometer head 30, regardless of the shape of the welding line WL, when welding the welding line WL having both the curved portion and the straight portion and periodically depicting the Lissajous figure while moving the galvanometer head 30 along the welding line WL.

[0175] TECHNICAL FIELD

[0176] The laser welding device according to Technical 5, wherein

[0177] The controller calculates the third overlap ratio based on a length (L3) by which the Lissajous figure on one side (IN1 side) of the n-th (n: an integer of 1 or more) cycle at the straight portion overlaps with the Lissajous figure on the one side (IN1 side) of the (n+1)-th cycle and a length (L4) of one cycle of the Lissajous figure,

[0178] The controller calculates the fourth overlap ratio based on a length (L1) by which the Lissajous figure on the other side (OUT1 side) of the n-th cycle at the straight portion overlaps with the Lissajous figure on the other side (OUT1 side) of the (n+1)-th cycle and a length (L2) of one cycle of the Lissajous figure.

[0179] Thus, the laser welding device 100 can set the overlap ratios in such a manner that the inner side and the outer side of the straight portion are respectively equal, and can make the heat input balance uniform on the inner side and the outer side respectively when performing laser welding by periodically depicting the Lissajous figure while moving the galvanometer head 30 by the robot 60 at the straight portion.

[0180] TECHNICAL FIELD

[0181] A laser welding method performed by a laser welding device (100) provided with at least a laser oscillator (10) that generates a laser, a machining head (galvanometer head 30), and a controller (50), and having:

[0182] a process of irradiating the laser light to the surface of the workpiece (200) in such a manner that the laser light is scanned two-dimensionally while traveling along the welding line (WL) having at least the curved portion (CV1, CV2,...) to periodically depict a prescribed pattern (Lissajous pattern LJ3);

[0183] a process of controlling the movement of the machining head along the welding line and the two-dimensional scanning of the laser light,

[0184] in the process of controlling the two-dimensional scanning of the laser light,

[0185] in such a manner that a first overlap ratio (a6) representing an overlap ratio of the pattern on one side (upper part of welding line IN2 side) resulting from the periodic depiction of the pattern at the curved portion is identical to a second overlap ratio (a5) representing an overlap ratio of the pattern on the other side (lower part of welding line OUT2 side) resulting from the periodic depiction of the pattern at the curved portion.

[0186] Thereby, the laser welding device 100 can make the heat input balance uniform at the inner side and the outer side from the laser LB irradiated from the galvanometer head 30 in the laser welding along the welding line WL having at least a curved shape (for example, a curved portion having a radius of curvature R, with reference to ​ ). Thus, the laser welding device 100 can suppress the deterioration of the quality of the weld bead formed by the laser welding.

[0187] The above, various embodiments have been described with reference to the drawings, but the present application is of course not limited to this example. As long as a person skilled in the art, it is obvious that various modification examples, correction examples, substitution examples, addition examples, deletion examples, equivalent examples can be thought within the scope of the patent technical solution, and these are of course also understood to belong to the technical scope of the present application. In addition, each of the constituent elements in the above various embodiments can be arbitrarily combined within the scope of the gist of the present application.

[0188] Note that the present application is based on Japanese Patent Application (Japanese Patent Application No. 2023-121954) filed on July 26, 2023, the content of which is incorporated herein by reference.

[0189] Industrial applicability

[0190] The present application is useful as a laser welding device and a laser welding method that make the heat input balance uniform at the inner side and the outer side in the laser welding along the welding line having a curved shape and suppress the deterioration of the quality of the weld bead.

[0191] Explanation of reference signs

[0192] 10 laser oscillator

[0193] 20 optical fiber

[0194] 30 galvanometer head

[0195] 31 housing

[0196] 32 collimator lens

[0197] 33 mirror

[0198] 34 condenser lens

[0199] 40 galvanometer scanner

[0200] 50 controller

[0201] 51 control section

[0202] 52 memory

[0203] 100 laser welding apparatus

[0204] 200 workpiece

[0205] LB laser beam

Claims

1. A laser welding apparatus, wherein, The laser welding device includes: A laser oscillator that generates laser light; A processing head that scans the laser two-dimensionally along a welding line having at least a curved portion, irradiating the surface of a workpiece with the laser in a manner that periodically traces a prescribed pattern; and A controller that controls the movement of the processing head along the welding line and the two-dimensional scanning of the laser. The controller controls the two-dimensional scanning of the laser at the curved portion in such a manner that a first overlap rate, representing the overlap rate of the graphics on one side obtained by periodic drawing of the graphics at the curved portion, is the same as a second overlap rate, representing the overlap rate of the graphics on the other side obtained by periodic drawing of the graphics at the curved portion.

2. The laser welding apparatus according to claim 1, wherein, The graphic is a Lissajous figure shaped like an 8 or an infinity symbol. The controller controls the two-dimensional scanning of the laser in such a way that the center position of the Lissajous pattern passes through the welding line, and the beginning and end positions of one cycle of the Lissajous pattern at the curved portion are different.

3. The laser welding apparatus according to claim 1, wherein, The controller includes a memory that stores one or more first parameters for defining the first overlap rate and one or more second parameters for defining the second overlap rate.

4. The laser welding apparatus according to claim 2, wherein, The controller calculates the first overlap rate based on the length of the overlap between the Lissajous figure on one side of the m-th cycle at the curve portion and the Lissajous figure on one side of the (m+1)-th cycle at the curve portion, and the length of one cycle of the Lissajous figure. The controller calculates the second overlap rate based on the length of the overlap between the Lissajous figure on the other side of the m-th cycle at the curve portion and the Lissajous figure on the (m+1)-th cycle at the curve portion, and the length of one cycle of the Lissajous figure. Where m is an integer greater than or equal to 1.

5. The laser welding apparatus according to claim 2, wherein, The welding line also has a straight section. The controller calculates a third overlap rate, representing the overlap rate of the Lissajous figures on one side obtained by periodically depicting the Lissajous figures at the straight section. The controller calculates a fourth overlap rate, representing the overlap rate of the Lissajous figures on the other side obtained by periodically depicting the Lissajous figures at the straight section. The controller controls the two-dimensional scanning of the laser at the curved portion in such a manner that the first overlap rate, the second overlap rate, the third overlap rate, and the fourth overlap rate are all the same.

6. The laser welding apparatus according to claim 5, wherein, The controller calculates the third overlap rate based on the length of the overlap between the Lissajous figure on one side of the nth cycle and the Lissajous figure on the same side of the (n+1)th cycle at the straight section, and the length of one cycle of the Lissajous figure. The controller calculates the fourth overlap rate based on the length of the overlap between the Lissajous figure on the other side of the nth cycle and the Lissajous figure on the other side of the (n+1)th cycle at the straight section, and the length of one cycle of the Lissajous figure. Where n is an integer greater than or equal to 1.

7. A laser welding method, wherein, The laser welding method is performed by a laser welding apparatus comprising at least a laser oscillator for generating laser light, a processing head, and a controller, and has the following characteristics: A process in which the laser is irradiated onto the surface of a workpiece in a manner that periodically depicts a predetermined pattern while traveling along a welding line having at least a curved portion, and... The process of controlling the movement of the processing head along the welding line and the two-dimensional scanning of the laser. In the process of controlling the two-dimensional scanning of the laser, The two-dimensional scanning of the laser at the curved portion is controlled in such a manner that a first overlap rate, representing the overlap rate of the graphic on one side obtained by periodic drawing of the graphic at the curved portion, is the same as a second overlap rate, representing the overlap rate of the graphic on the other side obtained by periodic drawing of the graphic at the curved portion.

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