Laser welding device and method for correcting a deviation in a laser beam irradiation position

Abstract

The laser welding device (100) comprises a laser oscillator (10), a laser head (30), a controller (50), and a table (70). The laser head (30) includes a laser scanner (40) that scans the laser beam (LB) two-dimensionally, an optical sensor (38), and an optical system (39) that causes the reflected backlight of the laser beam (LB) to fall onto the optical sensor (38). In a case where the laser beam (LB) is applied around a reflection point (72b) provided on the table (70) while the laser beam (LB) is scanned two-dimensionally by the laser scanner (40), the controller (50) corrects the deviation of the irradiation position of the laser beam (LB) based on the center position of the reflection point (72b) and the first peak position (O1) at which an output of the optical sensor (38) forms a peak.

Description

Laser welding device and method for correcting deviation in laser beam irradiation position

[0001] The present disclosure relates to a laser welding apparatus and a method for correcting deviation of a laser beam irradiation position.

[0002] Laser welding, which involves irradiating workpieces with a laser beam, can produce high-quality welds due to the high power density of the laser beam, and for this reason, laser welding has been widely used in recent years.

[0003] In laser welding, a scanning method is used to optically scan the irradiation position of the laser beam in order to weld the workpiece at high speed. In many cases, the laser beam is scanned two-dimensionally using a galvanometer mirror (see, for example, Patent Document 1).

[0004] However, in laser welding devices using galvanometer mirrors, a portion of the laser light is absorbed by the galvanometer mirror, causing the temperature of the galvanometer mirror to rise during laser welding. This can cause the laser light irradiation position to deviate from the set position. In addition, the temperature of the galvanometer mirror can rise due to heat generation from the drive circuit that drives the galvanometer mirror or a rise in the temperature of the internal atmosphere of the welding device during laser welding, causing the laser light irradiation position to deviate. As described above, various factors can cause the temperature of the galvanometer mirror to rise, resulting in a deviation in the laser light irradiation position, known as temperature drift.

[0005] In order to reduce deviation in the irradiation position of the laser beam due to temperature drift, for example, Patent Document 2 discloses a laser processing device equipped with a CCD camera and a temperature sensor attached to the mount of a galvanometer mirror, etc. The CCD camera detects the actual processing position of the laser beam, and corrects the deviation between the processing position and the set position using the temperature measured by the temperature sensor and a predetermined correction coefficient table.

[0006] JP 2005-95934 A JP 2005-40843 A

[0007] On the other hand, there are other factors besides temperature drift that can cause deviations in the laser beam irradiation position. The main ones are poor adjustment, wear, or deterioration over time of the manipulator that holds and moves the laser head. If the manipulator's moving mechanism is poorly adjusted, or if wear or deterioration over time occurs, the laser beam irradiation position may deviate from the set position.

[0008] To solve this problem, regular inspection and maintenance of the manipulator is necessary, but increasing the inspection frequency increases the downtime of the equipment and increases the labor and maintenance costs.

[0009] The present disclosure has been made in consideration of the above points, and its purpose is to provide a laser welding device and a method for correcting a laser beam irradiation position deviation that can correct a laser beam irradiation position deviation with a simple configuration.

[0010] In order to achieve the above object, a laser welding apparatus according to the present disclosure includes at least a laser oscillator that generates laser light, a laser head that receives the laser light and irradiates it toward a workpiece, a controller that controls at least the operation of the laser head, and a stage on which the workpiece is placed, wherein the laser head has a laser light scanner that scans the laser light in a first direction and a second direction intersecting the first direction, an optical sensor, and an optical system that causes reflected return light of the laser light to enter the optical sensor, and the controller controls the laser head to scan the laser light while causing the laser light to travel along a weld line. the stage has a correction unit, the correction unit has a reflector and a reflection spot provided on the surface of the reflector; the controller drives and controls the laser beam scanner so that the laser beam is irradiated around the reflection spot while scanning the laser beam two-dimensionally, and detects a first peak position where the output of the optical sensor becomes a peak; and the controller is configured to correct a deviation in the irradiation position of the laser beam based on the center position of the reflection spot and the first peak position.

[0011] a step of detecting a first peak position where the output of the optical sensor reaches a peak; a step of determining whether the first peak position coincides with the center position of the reflection spot; a step of terminating the correction operation if the first peak position coincides with the center position of the reflection spot; a step of calculating an amount of deviation between the first peak position and the center position of the reflection spot if the first peak position does not coincide with the center position of the reflection spot; and a step of correcting the deviation of the irradiation position of the laser beam based on the coordinates of the center position of the reflection spot and the amount of deviation.

[0012] According to the laser welding device of the present disclosure, deviation in the irradiation position of a laser beam can be corrected with a simple configuration. Also, according to the method of correcting deviation in the irradiation position of a laser beam of the present disclosure, deviation in the irradiation position of a laser beam can be corrected easily.

[0013] 5 is a schematic diagram of a laser welding apparatus according to embodiment 1. FIG. 6 is a schematic diagram of a laser beam scanner. FIG. 7 is a plan view of a stage. FIG. 8 is an enlarged plan view of a correction unit. FIG. 9 is a schematic cross-sectional view taken along line V-V in FIG. 4. FIG. 10 is a schematic diagram of a laser head. FIG. 11 is a flowchart showing a procedure for correcting deviation in the irradiation position of laser beam according to embodiment 1. FIG. 12 is a schematic diagram showing the output of an optical sensor plotted on the XY plane on which the laser beam is scanned. FIG. 13 is a schematic diagram showing the mechanism of error generation in correcting deviation in the irradiation angle of laser beam, where the laser beam is perpendicularly incident on the reflection spot. FIG. 14 is a schematic diagram showing the mechanism of error generation in correcting deviation in the irradiation angle of laser beam, where the laser beam is obliquely incident on the reflection spot. FIG. 15 is a schematic diagram showing the relationship between deviation in the angle of incidence from perpendicular incidence of laser beam and deviation in the XY plane. FIG. 16 is a flowchart showing a procedure for correcting deviation in the irradiation position of laser beam according to embodiment 2.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0015] First Embodiment [Configuration of Laser Welding Apparatus] [Configuration of Laser Welding Apparatus and Laser Beam Scanner] FIG. 1 is a schematic diagram showing the configuration of a laser welding apparatus according to this embodiment, and FIG. 2 is a schematic diagram showing the configuration of a laser beam scanner.

[0016] In the following description, the direction parallel to the traveling direction of the laser light LB from the mirror 33 toward the optical sensor 38 may be referred to as the X direction. The direction parallel to the optical axis of the laser light LB emitted from the laser head 30 may be referred to as the Z direction. The direction perpendicular to the X direction and the Z direction may be referred to as the Y direction. When the surface of the workpiece 200 is flat, the XY plane containing the X direction and the Y direction within the plane may be approximately parallel to the surface or may form a certain angle with the surface.

[0017] As shown in FIG. 1, the laser welding apparatus 100 includes a laser oscillator 10, an optical fiber 20, a laser head 30, a controller 50, a manipulator 60, and a stage 70.

[0018] The laser oscillator 10 is a laser light source that receives power from a power source (not shown) and generates laser light LB. The laser oscillator 10 may be configured with a single laser light source or multiple laser modules. In the latter case, laser light emitted from the multiple laser modules is combined and emitted as laser light LB. The laser light source or laser module used in the laser oscillator 10 is selected appropriately depending on the material of the workpiece 200, the shape of the welding portion, etc.

[0019] The optical fiber 20 is optically coupled to the laser oscillator 10. The laser light LB generated by the laser oscillator 10 is incident on the optical fiber 20 and transmitted through the optical fiber 20 toward the laser head 30.

[0020] The laser head 30 is attached to the end of the optical fiber 20 and irradiates the laser light LB transmitted from the optical fiber 20 toward the workpiece 200 .

[0021] The laser head 30 also has, as optical components, a collimation lens 32, a mirror 33, a first condenser lens 34, and a laser beam scanner 40. The laser head 30 also has a protective glass 35, an aperture 36, a second condenser lens 37, and an optical sensor 38. These optical components are housed inside a housing 31 while maintaining a predetermined arrangement relationship.

[0022] The collimation lens 32 receives the laser beam LB emitted from the optical fiber 20, converts it into parallel light, and directs it to the mirror 33. The collimation lens 32 is connected to a drive unit (not shown) and is configured to be movable in the Z direction in response to a control signal from the controller 50. By displacing the collimation lens 32 in the Z direction, the focal position of the laser beam LB can be changed, allowing the laser beam LB to be appropriately irradiated according to the shape of the workpiece 200. In other words, the collimation lens 32, in combination with a drive unit (not shown), also functions as a focal position adjustment mechanism for the laser beam LB. FIG. 1 illustrates an example in which the collimation lens 32 is configured with a single lens. While the focal position can be adjusted by driving the collimation lens 32 in the Z direction, the parallelism of the laser beam LB emitted from the collimation lens 32 is somewhat reduced. To prevent this, it is preferable to configure the collimation lens 32 with a combination of multiple lenses. The focal position of the laser beam LB may also be changed by displacing the first condenser lens 34 using a drive unit. The drive unit is, for example, an actuator or a motor.

[0023] The mirror 33 further transmits the laser beam LB that has passed through the collimation lens 32, causing it to be incident on the laser beam scanner 40. Meanwhile, the mirror 33 reflects the reflected return light of the laser beam LB that has been reflected by the reflection spot 72b (see FIGS. 3 to 5) on the stage 70 and passed through the laser beam scanner 40, toward the aperture 36 (see FIG. 6). The surface of the mirror 33 is disposed so as to form an angle of approximately 45 degrees with the optical axis of the laser beam LB that has passed through the collimation lens 32.

[0024] The first condenser lens 34 condenses the laser light LB, which has passed through the mirror 33 and been scanned by the laser light scanner 40 , onto the surface of the workpiece 200 .

[0025] The protective glass 35 is made of a material that is transparent to the laser light LB. The protective glass 35 prevents spatter and fumes generated during laser welding from entering the inside of the housing 31. Note that the spatter is the splattering of molten material from the workpiece 200, and the fumes are metal vapor generated when the workpiece 200 melts.

[0026] The aperture 36 is disposed between the mirror 33 and the second condenser lens 37 along the X direction. The second condenser lens 37 is disposed between the aperture 36 and the optical sensor 38 along the X direction. The functions of the aperture 36, the second condenser lens 37, and the optical sensor 38 will be described later. As will be described later, an optical system 39 formed by the mirror 33, the aperture 36, and the second condenser lens 37 is configured to direct the reflected return light of the laser beam LB to the optical sensor 38. Note that in FIG. 1 , the optical axis of the laser beam emitted from the end face of the optical fiber 20 and entering the laser beam scanner 40 is depicted as coinciding with the optical axis of the laser beam LB emitted from the laser beam scanner 40. However, this is a schematic illustration, and in reality, the two do not coincide due to the relationship between the first galvanometer mirror 41 and the second galvanometer mirror 42 (both of which are shown in FIG. 2 ) that constitute the laser beam scanner 40. This will be described in detail later using FIG. 6 .

[0027] 2, the laser beam scanner 40 is a known galvanometer scanner having a first galvanometer mirror 41 and a second galvanometer mirror 42. The first galvanometer mirror 41 has a first mirror 41a, a first rotation shaft 41b, and a first driver 41c, while the second galvanometer mirror 42 has a second mirror 42a, a second rotation shaft 42b, and a second driver 42c. The laser beam LB transmitted through the first condenser lens 34 is reflected by the first mirror 41a and then by the second mirror 42a, and is irradiated onto the surface of the workpiece 200.

[0028] For example, the first driver 41c and the second driver 42c are galvanometer motors, and the first rotation shaft 41b and the second rotation shaft 42b are output shafts of the motors. Although not shown, the first driver 41c is rotationally driven by a driver that operates in response to a control signal from the controller 50, causing the first mirror 41a attached to the first rotation shaft 41b to rotate about the axis of the first rotation shaft 41b. Similarly, the second driver 42c is rotationally driven by a driver that operates in response to a control signal from the controller 50, causing the second mirror 42a attached to the second rotation shaft 42b to rotate about the axis of the second rotation shaft 42b.

[0029] The first mirror 41a rotates around the axis of the first rotation shaft 41b to a predetermined angle, whereby the laser beam LB is scanned in the X direction. The second mirror 42a rotates around the axis of the second rotation shaft 42b to a predetermined angle, whereby the laser beam LB is scanned in the Y direction. In other words, the laser beam scanner 40 is configured to two-dimensionally scan the laser beam LB within the XY plane and irradiate it toward the workpiece 200.

[0030] 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 an output current and an on / off time that have a predetermined relationship with the output of the laser light LB to a power supply (not shown) connected to the laser oscillator 10. The controller 50 also controls the output of the laser light LB.

[0031] The controller 50 also controls the operation of the laser head 30 in accordance with the content of the selected laser welding program. Specifically, the controller 50 controls the driving of the laser beam scanner 40 and the driving unit (not shown) of the collimation lens 32 provided in the laser head 30. The controller 50 also controls the operation of the manipulator 60.

[0032] The controller 50 has an integrated circuit such as an LSI or a microcomputer as an information processing unit 51, and the functions of the controller 50 described above are realized by executing a laser welding program, which is software, on this integrated circuit. The controller 50 also has a memory device such as a RAM, ROM, or SSD as a storage unit 52. The laser welding program is stored in the storage unit 52 and is called by the controller 50 in response to a command from the controller 50. The storage unit 52 may be an SD card (registered trademark) that is detachable from the controller 50. The storage unit 52 may also be provided in a location separate from the controller 50.

[0033] The storage unit 52 also stores correction results of the irradiation position of the laser beam LB, which will be described later. For example, the amount of deviation of the irradiation position of the laser beam LB due to temperature drift and the correction results thereof are stored in the storage unit 52. Specifically, the amount of deviation of the irradiation position of the laser beam LB due to absorption of the laser beam LB by the first galvanometer mirror 41 and the second galvanometer mirror 42 and the correction results thereof are stored in the storage unit 52. Alternatively, the amount of deviation of the irradiation position of the laser beam LB due to heat generation in a drive circuit that drives these mirrors and the correction results thereof are stored in the storage unit 52.

[0034] The controller 50 for controlling the operation of the laser head 30 and the controller 50 for controlling the output of the laser light LB may be provided separately.

[0035] The manipulator 60 is an articulated robot and is attached to the housing 31 of the laser head 30. The manipulator 60 is also connected to the controller 50 so as to be able to exchange signals, and moves the laser head 30 to trace a predetermined trajectory in accordance with the laser welding program described above. As a result, the laser beam LB is irradiated onto the surface of the workpiece 200 while being scanned two-dimensionally along and around the weld line WL.

[0036] It is also possible to provide a separate controller (not shown) for controlling the operation of the manipulator 60. However, in this case, the controller 60 must also be configured to be able to communicate data with the controller 50 that controls the operation of the laser head 30 in order to configure the irradiation position of the laser beam LB.

[0037] The stage 70 has a main body 71 and a correction section 72. The configuration of the stage 70 will be described in detail later.

[0038] The laser welding apparatus 100 shown in FIG. 1 can perform laser welding on workpieces 200 of various shapes.

[0039] [Configuration of Stage and Laser Head] FIG. 3 shows a plan view of the stage, FIG. 4 shows an enlarged plan view of the correction unit, and FIG. 5 shows a schematic cross-sectional view taken along line VV in FIG.

[0040] 3, the stage 70 has a main body 71 and a correction unit 72. The workpiece 200 is placed on the main body 71, and the workpiece 200 is welded by irradiation with laser light LB. For this reason, although not shown, the main body 71 includes a portion having a flat surface that supports the workpiece 200 and a portion through which the laser light LB passes.

[0041] On the other hand, the correction unit 72 is disposed in one corner of the main body 71. As shown in FIGS. 4 and 5 , the correction unit 72 includes a reflector 72a that reflects the laser beam LB and a reflection spot 72b provided on the surface of the reflector 72a. The diameter d of the reflection spot 72b is set to be approximately 1 / 10 to 1x (1x) the diameter of the laser beam LB. The shape of the reflection spot 72b shown in FIGS. 4 and 5 is circular when viewed from the Z direction and plate-like when viewed in cross section, but is not limited thereto. For example, the reflection spot 72b may be rectangular when viewed from the Z direction. The reflection spot 72b may be provided so that the surface of the reflection spot 72b is flush with the surface of the reflector 72a.

[0042] The reflectance of the laser beam LB at the reflection spot 72b is designed to be higher than the reflectance of the laser beam LB at the reflection plate 72a. While not limiting the scope of the present disclosure, the correction unit 72 can be configured as follows, for example. For example, the correction unit 72 can be a printed circuit board with a copper foil of a predetermined shape on its surface. In this case, the reflection plate 72a can be a plate portion of epoxy resin from which the copper foil has been removed, and the reflection spot 72b can be a copper foil spot-shaped with a predetermined diameter. It is preferable to gold-plat the copper foil portion. This sufficiently increases the difference in reflectance of the laser beam LB between the copper foil portion and the epoxy resin, thereby easily fulfilling the role of the correction unit 72. The reflection spot 72b is not limited to copper or gold, and can be made of any material that has a reflectance of the laser beam LB equal to or higher than a predetermined value. For example, aluminum or silver may be used. Furthermore, the correction unit 72 other than the reflection spot 72b can be made of a material that has a lower reflectance of the laser beam LB than the reflection spot 72b.

[0043] As will be described later, the correction unit 72 is used to determine whether or not the aforementioned temperature drift occurs in the laser light scanner 40, and if so, to measure the amount of correction for the temperature drift.

[0044] The position of the correction unit 72 on the stage 70 is not particularly limited to that shown in FIG. 3 . However, during laser welding of the workpiece 200, spatter and fumes may fly near the weld line WL, and if the workpiece 200 contains aluminum, smut may adhere to it. To prevent these from adhering to the reflection spot 72b, the weld line WL of the workpiece 200 must be positioned at a predetermined distance or more from the correction unit 72. Furthermore, because the correction unit 72 is not used during the welding process, a cover (not shown) may be attached to protect its surface.

[0045] 4, in other words, while being scanned sequentially at predetermined intervals in both the X and Y directions, the laser beam LB is irradiated onto the correction unit 72. When the laser beam LB is incident on the reflection spot 72b, it is reflected along its original optical path with almost no scattering or the like. However, laser beams other than those incident perpendicularly to the reflection spot 72b are not reflected back along the original optical path, but are slightly deviated from the original optical path. As will be described later, if this deviation is also corrected, the accuracy of correction for deviations in the irradiation position of the laser beam LB can be further improved.

[0046] Fig. 6 shows a schematic configuration diagram of the laser head. For the sake of convenience, the housing 31 is not shown in Fig. 6. The laser beam scanner 40 is also shown in a simplified form.

[0047] 6, the laser light LB guided from the optical fiber 20 into the housing 31 is collimated by the collimation lens 32. The collimated laser light LB passes through a mirror 33. The laser light LB that has passed through the mirror 33 is incident on the laser light scanner 40. In this case, the incident position P1 of the laser light LB on the laser light scanner 40 is on the optical axis a-a' of the laser light LB guided from the optical fiber 20 into the housing 31.

[0048] The laser beam LB that passes through the laser beam scanner 40 is emitted from position P2 of the laser beam scanner 40. When the laser beam scanner 40 is not operated and the first galvanometer mirror 41 and the second galvanometer mirror 42 are each in their initial positions, position P2 is shown in FIG. 6 as being on the optical axis c-c'. However, when the laser beam LB is scanned, position P2 is located at a different position along the optical axis c-c' (not shown). Note that whether the laser beam LB is scanned or not scanned by the laser beam scanner 40, the actual laser beam LB is reflected by the first galvanometer mirror 41 and the second galvanometer mirror 42 inside the laser beam scanner 40. Therefore, the optical axis a-a' of the incident beam does not coincide with the optical axis c-c' of the emitted beam. For this reason, in FIG. 6, the laser beam LB emitted from the laser beam scanner 40 is depicted as being shifted by a predetermined distance in the X direction.

[0049] The laser beam LB is incident on the reflector 72a at position P3 and is reflected from the reflector 72a toward the laser beam scanner 40, i.e., approximately along the Z direction, in the direction opposite to the incident direction. The reflected returning light of the laser beam LB is incident on the laser beam scanner 40 at position P4, is emitted to the outside of the laser beam scanner 40 at position P5, and then is incident on the mirror 33. After incident on the mirror 33 at position P6, the laser beam LB is reflected in the X direction and enters the aperture 36. The light amount and diameter of the laser beam LB narrowed by the aperture 36 are adjusted. The optical axis of the laser beam LB traveling from position P6 toward the center position P7 of the optical sensor 38 is indicated by b-b' in FIG. 6.

[0050] The second condenser lens 37 condenses the laser light LB that has passed through the aperture 36 onto a light receiving surface (not shown) of the optical sensor 38. That is, the optical system 39 causes the reflected return light of the laser light LB that has passed through the protective glass 35 and entered the housing 31 to be incident on the optical sensor 38.

[0051] The optical sensor 38 outputs an electrical signal corresponding to the amount of light of the incident laser beam LB. This output signal is input to the controller 50 and is used to correct the irradiation position of the laser beam LB, which will be described later.

[0052] [Method for correcting deviation of laser beam irradiation position] Fig. 7 shows a flowchart of the procedure for correcting deviation of laser beam irradiation position, and Fig. 8 shows a schematic diagram in which the output of the optical sensor is plotted on the XY plane along which the laser beam is scanned. For the sake of explanation, Fig. 8 assumes that the angle of the incident beam with respect to the reflection spot 72b on the XY plane is always perpendicular.

[0053] 3, the center position of the reflection spot 72b on the XY plane is set to coincide with the galvanometer origin of the laser light scanner 40, which is defined as the origin O. Here, the galvanometer origin corresponds to the initial position of the laser light LB on the XY plane of the laser head 30 in the absence of temperature drift. In other words, the galvanometer origin corresponds to the initial position of the tip of the manipulator 60 on the XY plane. The origin O is stored in the storage unit 52 as coordinates on the XY plane.

[0054] In the absence of temperature drift, the optical sensor 38 generates an output signal only when the laser beam LB is irradiated onto the origin O or its vicinity. In this case, "vicinity" refers to a distance from the origin O that is approximately 1 / 10 to 1 / 2 of the radius when the laser beam LB is focused on the XY plane. Needless to say, this distance can also be shortened. In this case, the accuracy of the correction described below will be higher.

[0055] On the other hand, if a temperature drift occurs, the influence of the temperature drift may cause the origin during scanning to deviate from the origin O, which corresponds to the galvanometer origin, when the laser light LB is scanned. In other words, when the laser light LB is irradiated at a position that is more than a predetermined distance away from the origin O, the optical sensor 38 may generate an output signal.

[0056] If this occurs, the laser beam LB may not be irradiated onto the workpiece 200 along the desired irradiation trajectory, which may result in poor welding.

[0057] The "origin during scanning" refers to the actual irradiation point of the laser beam LB on the XY plane when the position command in the X-axis direction and the position command in the Y-axis direction are both zero (or a fixed value corresponding to the laser beam scanner 40; for the sake of explanation, this value will be assumed to be zero hereinafter) when the laser beam scanner 40 irradiates the surface of the workpiece 200 or stage 70 during actual welding or during correction, which will be described later. The position command in the X-axis direction is a rotation position command (hereinafter referred to as a rotation command) for the first drive unit 41c, and the position command in the Y-axis direction is a rotation command for the second drive unit 42c. In this case, since the position commands in the X-axis direction and the Y-axis direction are both zero, if there is no temperature drift, the origin during scanning coincides with the galvanometer origin.

[0058] Therefore, by correcting the irradiation position of the laser beam LB, in this case, the deviation of the origin position during scanning, using the procedure shown in Fig. 7, the laser beam LB can be irradiated onto the workpiece 200 along a desired irradiation trajectory, thereby suppressing the occurrence of welding defects.

[0059] The manipulator 60 is moved to move the laser beam scanner 40 of the laser head 30 to the center position of the reflection spot 72b of the correction unit 72, that is, the origin O on the XY plane (step S1 in FIG. 7).

[0060] The laser beam scanner 40 is operated to irradiate the area around the origin O with the laser beam LB while scanning along the dashed line shown in FIG. 4 (step S2 in FIG. 7 ). In step S2, the manipulator 60 is not moved. That is, the position of the laser head 30 itself is maintained at the origin O, and the laser beam LB is scanned along the dashed line shown in FIG. 4 . The output of the laser beam LB in step S2 is significantly reduced compared to that during laser welding to prevent damage to the reflector 72 a and the optical sensor 38. For example, if the output of the laser beam LB during laser welding is several kW, the output of the laser beam LB in step S2 may be a value (several mW) that does not damage the reflector 72 a or the reflection spot 72 b and is sufficiently detectable by the optical sensor 38. Note that, typically, the laser oscillator 10 may use a guide laser (not shown) to visually confirm the irradiation position of the laser beam LB. However, the laser beam emitted from this guide laser may be used for scanning in the aforementioned step S2.

[0061] During or after step S2, the output of the optical sensor 38 is checked to determine a first peak position O1 where the output reaches its peak (step S3 in FIG. 7). The first peak position O1 is expressed as coordinates on the XY plane. The coordinates of the first peak position O1 and the output of the optical sensor 38 at the first peak position O1 are stored in the storage unit 52.

[0062] Next, the information processing unit 51 of the controller 50 determines whether the first peak position O1 coincides with the origin O (step S4 in FIG. 7). Note that in this specification, "coincidence" does not only mean coincidence in the strict sense, but also includes the case where the distance on the XY plane between the first peak position O1 and the origin O is equal to or less than approximately 1 / 10 to 1 / 2 of the beam radius when the laser light LB is focused. Needless to say, this distance can be shortened, but in that case, the accuracy of correction will be higher.

[0063] The position where the laser beam LB reflected by the first galvanometer mirror 41 and the second galvanometer mirror 42, which are fixed at preset initial positions, is irradiated onto the surface of the stage 70 is the "origin during scanning" described above. For example, the laser head 30 is moved to the center position of the reflection spot 72b of the correction unit 72 on the XY plane, and in this state, the laser beam LB is reflected by the first galvanometer mirror 41 and the second galvanometer mirror 42, which are each fixed at their initial positions. In this case, if there is no temperature drift, the origin during scanning of the laser beam LB will coincide with the origin O described above, and the output from the optical sensor 38 will reach its peak.

[0064] If the determination result in step S4 is positive, that is, if the first peak position O1 coincides with the origin O, it is determined that the origin during scanning with the laser beam LB coincides with the origin O. In other words, it can be determined that no temperature drift has occurred in the laser beam scanner 40, and the series of operations is terminated.

[0065] On the other hand, if the determination result in step S4 is negative, that is, if the first peak position O1 does not coincide with the origin O, the peak of the output of the optical sensor 38 appears at a position on the XY plane away from the origin O, as shown in Fig. 8. In the example shown in Fig. 7, the first peak position O1 is shifted to the negative side in both the X and Y directions with respect to the origin O.

[0066] In this case, the controller 50 acquires the difference between the coordinates of the origin O and the coordinates of the first peak position O1, i.e., the amount of deviation between the origin O and the first peak position O1, and stores the amount of deviation in the memory unit 52 (step S5 in Figure 7).

[0067] The information processing unit 51 of the controller 50 corrects the deviation of the origin position during scanning using equations (1) and (2) based on the coordinates of the origin O and the deviation amount acquired in step S5 (step S6 in Figure 7).

[0068] In the example shown in FIG. 7, the origin position during scanning after correction satisfies the relationships shown in equations (1) and (2).

[0069] Xc = X0 - Xa (1) Yc = Y0 - Ya (2) where, X0: X coordinate of the origin when scanning without temperature drift Y0: Y coordinate of the origin when scanning without temperature drift Xc: X coordinate of the origin when scanning after correction Yc: Y coordinate of the origin when scanning after correction Xa: X-direction deviation between the origin O and the first peak position O1 Ya: Y-direction deviation between the origin O and the first peak position O1 As mentioned above, since the galvano origin of the laser light scanner 40 is the origin O, in equations (1) and (2), the X-coordinate of the origin X0 and the Y-coordinate of the origin Y0 can both be set to zero. Note that in the example shown in FIG. 8, the deviation amounts Xa and Ya are both negative values.

[0070] In actual correction, the rotation commands of the first drive unit 41c and the second drive unit 42c are corrected according to the results of equations (1) and (2). That is, the rotation command corresponding to the initially set origin (=(X0, Y0)) during scanning is corrected by adding or subtracting a rotation amount corresponding to the deviation amounts Xa and Ya to or from the rotation command corresponding to the origin during scanning.

[0071] The coordinates (Xc, Yc) of the origin during scanning and the amounts of deviation Xa, Ya after correction are stored in the storage unit 52. The amounts of correction of the rotation commands for the first drive unit 41c and the second drive unit 42c corresponding to the amounts of deviation Xa, Ya, respectively, are also stored in the storage unit 52. When scanning with the laser beam LB in subsequent laser welding, the coordinates of the origin during scanning are set to (Xc, Yc).

[0072] As shown in FIG. 6 , the laser beam LB is not reflected back along its original optical path unless it is perpendicularly incident on the reflection spot 72b. In other words, position P2 where the laser beam LB is emitted from the laser beam scanner 40 does not strictly coincide with position P4 where the reflected beam is incident on the laser beam scanner 40 unless it is perpendicularly incident on the reflection spot 72b. Therefore, assuming that the beam is perpendicularly incident on the reflection spot 72b, an error due to this incident angle is added to the X- and Y-directional deviations Xa and Ya between the origin O and the first peak position O1 shown in FIG. 8 . Correcting the deviations while taking this error into account can improve the accuracy of the correction. The mechanism of error generation and the correction method are outlined below. In the example shown below, positions P2 and P4 both correspond to positions on the surface of the second mirror 42a.

[0073] 9A and 9B are schematic diagrams illustrating the mechanism of error generation in correcting the deviation in the irradiation angle of the laser beam. Fig. 9A is a schematic diagram illustrating the case where the laser beam LB is perpendicularly incident on the reflection spot 72b, and Fig. 9B is a schematic diagram illustrating the case where the laser beam is obliquely incident on the reflection spot. Note that the angle α in Fig. 9B indicates the deviation of the incident angle from the case where the laser beam is perpendicularly incident. In the example shown in Fig. 9B, the angle α is 0°<α<90°. However, in order for the reflected light from the reflection spot 72b to be incident on the optical sensor 38 along the reflection route shown in Fig. 6, it is desirable for the angle α to be as close to 0° as possible.

[0074] 10 is a schematic diagram showing the relationship between the amount of deviation of the incident angle from perpendicular incidence of the laser light and the amount of positional deviation in the XY plane. As the amount of deviation α of the incident angle increases, the amount of deviation Xa1 and Ya1 of the peak position on the X axis or Y axis increases. Although not shown, if the amount of deviation α of the incident angle is too large, the reflected light may not be able to enter the optical sensor 38, making sensing impossible. Therefore, as mentioned above, it is preferable to set the amount of deviation α of the incident angle as close to 0 as possible.

[0075] 9A and 9B, the incident light to the reflection spot 72b is indicated by a solid arrow, and the reflected light is indicated by a dotted arrow. In Fig. 9A, the incident light is perpendicular to the reflection spot 72b, so the optical path of the reflected light is also perpendicular to the reflection spot 72b, and the two light paths coincide at positions P2 and P4 on the surface of the second mirror 42a.

[0076] On the other hand, in the example shown in FIG. 9B , the incident angle of the incident light with respect to the normal to the reflection spot 72b is α (0°<α<90°), and therefore the optical path of the reflected light also forms an angle α with respect to the normal to the reflection spot 72b. Therefore, as shown in FIG. 9B , the position P2 where the incident light is incident on the surface of the second mirror 42a and the position P4 where the reflected light is incident do not coincide. In a typical optical system, this angle α is very small, so if the focal length of the first focusing lens 34 is ff, the deviation amount, i.e., the distance between positions P2 and P4, is approximately ff·α. Once the optical system is determined, this deviation amount ff·α can be measured in advance and stored in the controller 50. Needless to say, as the deviation amount α of the incident angle decreases, the deviation amount ff·α also decreases. In the example shown in FIG. 10 , the deviation amounts Xa1 and Ya1 described above monotonically increase with the deviation amount α of the incident angle.

[0077] Taking this into consideration, the X and Y coordinates of the origin during scanning after correction are determined based on the following equations (3) and (4) instead of equations (1) and (2).

[0078] Xc1=X0-Xa-Xa1 (3) Yc1=Y0-Ya-Ya1 (4) Where, Xc1: X coordinate of the origin during scanning after correction, taking into account the angle of incidence on the reflection spot Yc1: Y coordinate of the origin during scanning after correction, taking into account the angle of incidence on the reflection spot Xa1: deviation amount in the X direction between the origin O and the first peak position O1, taking into account the angle of incidence on the reflection spot Ya1: deviation amount in the Y direction between the origin O and the first peak position O1, taking into account the angle of incidence on the reflection spot.

[0079] The deviation amounts Xa1 and Ya1 depend on the optical system of the laser light scanner 40 and the installation position of the correction unit 72, and can be measured in advance under conditions without temperature drift and stored in the controller 50.

[0080] [Effects, etc.] As described above, the laser welding apparatus 100 according to this embodiment includes at least the laser oscillator 10 that generates the laser beam LB, the laser head 30 that receives the laser beam LB and irradiates it toward the workpiece 200, the controller 50 that controls the operation of the laser head 30 and the output P of the laser beam LB, and the stage 70 on which the workpiece 200 is placed.

[0081] The laser head 30 has a laser beam scanner 40 that scans the laser beam LB in both the X direction (first direction) and the Y direction (second direction) that intersects with the X direction. The laser head 30 also has an optical sensor 38. The laser head 30 further has an optical system 39 that causes reflected return light of the laser beam LB to enter the optical sensor 38. The optical system 39 is composed of a mirror 33, an aperture 36, and a second condenser lens 37.

[0082] The controller 50 drives and controls the laser beam scanner 40 so that the laser beam LB scans two-dimensionally while causing the laser beam LB to travel along the weld line WL.

[0083] The stage 70 has a main body 71 and a correction unit 72. The correction unit 72 has a reflecting plate 72a and a reflecting spot 72b provided on the surface of the reflecting plate 72a.

[0084] The controller 50 controls the driving of the laser beam scanner 40 to irradiate the laser beam LB around the reflection spot 72b while scanning the laser beam LB two-dimensionally, and detects a first peak position O1 where the output of the optical sensor 38 reaches a peak. The controller 50 is configured to correct a deviation in the irradiation position of the laser beam LB based on the origin O, which is the center position of the reflection spot 72b, and the first peak position O1. In the present disclosure, "around the reflection spot 72b" refers to an area including the reflection spot 72b itself and the periphery of the reflection spot 72b.

[0085] According to this embodiment, misalignment of the irradiation position of the laser beam LB can be corrected with an extremely simple configuration in which the stage 70 is provided with the correction unit 72 having the reflection spot 72b, and the laser head 30 is provided with the optical sensor 38 and the optical system 39 that causes the reflected return light of the laser beam LB to enter the optical sensor 38. Furthermore, by providing the optical system 39, particularly the aperture 36, the amount of light incident on the optical sensor 38 can be controlled, and saturation of the output signal of the optical sensor 38 can be prevented. This makes it possible to accurately detect the first peak position O1 where the output of the optical sensor 38 reaches its peak.

[0086] Furthermore, the laser beam LB can be scanned two-dimensionally and accurately irradiated along the welding line WL at a desired position on the workpiece 200. This reduces the occurrence of welding defects and improves the welding yield.

[0087] The controller 50 is also configured to correct the deviation of the origin position during scanning with the laser light LB based on the deviation amount between the origin O, which is the center position of the reflection spot 72b, and the first peak position O1.

[0088] In this way, deviation of the irradiation position of the laser beam LB due to temperature drift in particular can be easily corrected.

[0089] The laser oscillator 10 and the laser head 30 are connected by an optical fiber 20 , and the laser light LB is transmitted from the laser oscillator 10 to the laser head 30 through the optical fiber 20 .

[0090] By providing the optical fiber 20 in this manner, it becomes possible to perform laser welding on the workpiece 200 that is installed at a position distant from the laser oscillator 10. This increases the degree of freedom in arranging each part of the laser welding apparatus 100.

[0091] The laser beam scanner 40 is composed of a first galvanometer mirror 41 that scans the laser beam LB in the X direction, and a second galvanometer mirror 42 that scans the laser beam LB in the Y direction.

[0092] By configuring the laser beam scanner 40 in this manner, it is possible to easily perform two-dimensional scanning with the laser beam LB. Furthermore, since a known galvanometer scanner is used as the laser beam scanner 40, an increase in the cost of the laser welding apparatus 100 can be suppressed.

[0093] The laser head 30 further includes a collimation lens 32, which is configured to change the focal position of the laser beam LB along the Z direction, which intersects with both the X and Y directions. In other words, the collimation lens 32 is configured to change the focal position of the laser beam LB along the Z direction, which intersects with the surface of the workpiece 200. In other words, the collimation lens 32, in combination with a drive unit (not shown), also functions as a focal position adjustment mechanism for the laser beam LB. In other words, the focal position can be changed to match any irradiation position during welding, thereby increasing the degree of freedom in setting welding conditions.

[0094] In this way, the focal position of the laser light LB can be easily changed, and the laser light LB can be appropriately irradiated according to the shape of the workpiece 200.

[0095] The laser welding apparatus 100 further includes a manipulator 60 to which the laser head 30 is attached, and the controller 50 controls the operation of the manipulator 60. The manipulator 60 moves the laser head 30 in a predetermined direction relative to the surface of the workpiece 200.

[0096] By providing the manipulator 60 in this manner, it is possible to change the welding direction of the laser beam LB or the position of the welding point. Furthermore, laser welding can be easily performed on the workpiece 200 having a complex shape, for example, a three-dimensional shape.

[0097] The method for correcting the deviation of the laser beam irradiation position according to this embodiment includes at least a first step (step S1 in FIG. 7) of moving the laser head 30 to an origin O, which is the center position of the reflection spot 72b provided on the stage 70, and a second step (step S2 in FIG. 7) of operating the laser beam scanner 40 to irradiate the laser beam LB around the origin O while scanning it two-dimensionally.

[0098] In addition, the correction method of this embodiment includes a third step (step S3 in FIG. 7) of confirming the first peak position O1 where the output of the optical sensor 38 reaches its peak, and a fourth step (step S3 in FIG. 7) of determining whether the first peak position O1 coincides with the origin O.

[0099] The correction method of this embodiment includes a step of terminating the correction process if the determination result in the fourth step is affirmative, that is, if the first peak position O1 coincides with the origin O.

[0100] The correction method of this embodiment includes a step of calculating the amount of deviation between the first peak position O1 and the origin O if the judgment result of the fourth step is negative, that is, if the first peak position O1 does not coincide with the origin O, and a step of correcting the deviation of the irradiation position of the laser light LB based on the coordinates of the origin O and the amount of deviation.

[0101] This makes it possible to easily correct deviations in the irradiation position of the laser beam LB, particularly those caused by temperature drift. Furthermore, the laser beam LB can be scanned two-dimensionally and accurately irradiated onto a desired position on the workpiece 200 along the weld line WL. This reduces the occurrence of welding defects and improves the welding yield.

[0102] Second Embodiment FIG. 11 is a flowchart showing a procedure for correcting deviation in the irradiation position of laser light according to this embodiment.

[0103] In the first embodiment, the device configuration and correction procedure for correcting the deviation of the irradiation position of the laser beam LB due to the temperature drift have been described.

[0104] On the other hand, as described above, deviation in the irradiation position of the laser beam LB can also occur due to insufficient adjustment, wear, or deterioration over time of the manipulator 60. If the manipulator 60 is insufficiently adjusted, or if wear or deterioration over time occurs, the tip position of the manipulator 60 itself may be deviated from the position previously set in the welding program, etc. In this case, the position of the laser head 30 also deviates, making it impossible to irradiate the laser beam LB at the predetermined position on the workpiece 200.

[0105] Therefore, the adjustment state of the manipulator 60 is checked according to the procedure shown in Fig. 11, and the deviation of the irradiation position of the laser beam LB is corrected based on the result of the check, as will be described in detail below.

[0106] First, the manipulator 60 is moved from its initial position to move the laser beam scanner 40 of the laser head 30 to the origin O (step S10). The laser beam scanner 40 is operated to irradiate the area around the origin O with the laser beam LB while scanning along the dashed line shown in FIG. 4 (step S11). Furthermore, the output of the optical sensor 38 is checked to confirm the first peak position O1 where the output reaches its peak (step S12). Subsequently, the amount of deviation (first deviation) between the origin O and the first peak position O1 is acquired and stored in the storage unit 52 (step S13). Note that steps S10 to S13 are the same processes as steps S1 to S3 and S5 in FIG. 7.

[0107] Next, the manipulator 60 is moved to move the laser beam scanner 40 of the laser head 30 to a predetermined position P (hereinafter simply referred to as position P; see FIG. 4 ) near the origin O (step S14). Position P is a position previously stored in the controller 50 during robot teaching. In the example shown in FIG. 4 , position P is offset from the origin O by one division in each of the X and Y directions on the scanning trajectory of the laser beam LB indicated by the dashed line. However, position P relative to the origin O is not limited to this and may be set to another position. The distance between position P and origin O is also a value previously stored in the controller 50. Note that it is desirable that both position P and origin O are not on the X or Y axis of the XY plane. This is because correction of the irradiation position deviation of the laser beam LB, which requires maintenance of the manipulator 60, may exist on both the X and Y axes. The specific content of step S14 is the same as step S10, except that the destination of the laser beam scanner 40 is different.

[0108] Furthermore, the laser beam scanner 40 is operated to irradiate the area around the position P with the laser beam LB while scanning along the dashed line shown in FIG. 4 (step S15). The output of the optical sensor 38 is checked to identify the second peak position O2 where the output reaches its peak (step S16). Next, the amount of deviation (second deviation amount) between the position P and the second peak position O2 is obtained and stored in the storage unit 52 (step S17). Note that steps S15 to S17 are the same processes as steps S11 to S13.

[0109] Next, the information processing unit 51 of the controller 50 calculates the amount of deviation between the first peak position O1 based on the origin O and the second peak position O2 based on the position P, in other words, the difference between the first deviation and the second deviation. Furthermore, it is determined whether the amount of deviation between the first peak position O1 based on the origin O and the second peak position O2 based on the position P is within an allowable range (step S18).

[0110] That is, in step S18, when the amount of deviation in the X direction between the origin O and the second peak position O2 based on the position P is taken as Xb, and the amount of deviation in the Y direction between the origin O and the second peak position O2 based on the position P is taken as Yb, it is determined whether or not the relationship satisfying equations (5) and (6) is satisfied.

[0111] |Xa-Xb|≦εx (5) |Ya-Yb|≦εy (6) Here, εx is the upper limit of the allowable difference in the X direction, and εy is the upper limit of the allowable difference in the Y direction. εx and εy are set appropriately depending on the processing tolerance allowed during laser welding, the assembly tolerance of the manipulator 60, etc.

[0112] If the determination result in step S18 is positive, it can be determined that the position of the manipulator 60 has not deviated from the set position, and that the difference is within an allowable range, and the process proceeds to step S19.

[0113] Steps S19 to S21 are the same as steps S4 to S6 in Fig. 7, and therefore detailed description thereof will be omitted. That is, if the determination result of step S19 is positive, the correction work is terminated. If the determination result of step S19 is negative, the deviation of the origin position during scanning is corrected based on the coordinates of the origin O and the deviation amount acquired in step S13 (step S20).

[0114] On the other hand, if the determination result in step S18 is negative, it can be determined that the position of the manipulator 60 has deviated from the set position beyond the allowable range. Therefore, the laser welding device 100 is stopped, and the manipulator 60 is maintained and its position, attitude, etc. are readjusted.

[0115] Thereafter, the process returns to step S10 and repeats the series of processes until the determination result of step S18 becomes affirmative. Then, steps S19 and onward are executed to correct the deviation of the origin position during scanning, and the correction process is completed.

[0116] As described above, the laser welding apparatus 100 according to this embodiment executes the first process and the second process.

[0117] In the first process, the laser head 30 is moved to the center position of the reflection spot 72b, i.e., the origin O, and the laser light LB is irradiated around the reflection spot 72b (around the origin O) while scanning the laser light LB two-dimensionally (steps S10 and S11 in Figure 11).

[0118] In the second process, the laser head 30 is moved to a position P near the origin O, and the laser light LB is scanned two-dimensionally while irradiating the laser light LB around the reflection spot 72b (around the position P) (steps S14 and S15 in Figure 11).

[0119] When the first process and the second process are executed, the controller 50 is configured to correct the deviation in the irradiation position of the laser light LB based on the origin O, which is the center position of the reflection spot 72b, the first peak position O1 where the output of the optical sensor 38 reaches its peak in the first process, and the second peak position O2 where the output of the optical sensor 38 reaches its peak in the second process.

[0120] Furthermore, if the amount of deviation between the first peak position O1 and the second peak position O2 is within a predetermined tolerance range, the controller 50 is configured to correct the deviation of the origin position during scanning with the laser light LB based on the amount of deviation between the origin O and the first peak position O1.

[0121] Furthermore, the method for correcting the deviation of the irradiation position of the laser beam LB in this embodiment includes at least a first step of moving the laser head 30 to the origin O (step S10 in FIG. 11).

[0122] Furthermore, the correction method of this embodiment includes a second step (step S11 in FIG. 11) of operating the laser light scanner 40 to irradiate the area around the origin O while scanning the laser light LB two-dimensionally, a third step (step S12 in FIG. 11) of confirming a first peak position O1 where the output of the optical sensor 38 reaches its peak, and a fourth step (step S15 in FIG. 11) of determining the amount of deviation (first deviation amount) between the first peak position O1 and the origin O.

[0123] Furthermore, the correction method of this embodiment includes a fifth step (step S14 in FIG. 11) of moving the laser head 30 to the aforementioned position P after determining the first deviation amount, and a sixth step (step S15 in FIG. 11) of operating the laser light scanner 40 to irradiate the area around the position P with the laser light LB while scanning it two-dimensionally.

[0124] The correction method of this embodiment includes, after the sixth step, a seventh step (step S16 in FIG. 11) of confirming the second peak position O2 where the output of the optical sensor 38 reaches its peak, and an eighth step (step S17 in FIG. 11) of calculating the amount of deviation (second deviation amount) between the second peak position O2 and position P.

[0125] Furthermore, the correction method of this embodiment includes a ninth step (step S18 in FIG. 11) of determining whether or not the difference between the first and second deviation amounts is within an allowable range.

[0126] The correction method of this embodiment further includes a tenth step (step S19 in FIG. 11) of determining whether the first peak position O1 coincides with the origin O if the judgment result of the ninth step is positive, that is, if the difference between the first deviation amount and the second deviation amount is within the aforementioned allowable range.

[0127] The correction method of this embodiment includes a step of terminating the correction process if the determination result in the tenth step is affirmative, that is, if the first peak position O1 coincides with the origin O.

[0128] The correction method of this embodiment includes an eleventh step in which, if the judgment result of the tenth step is negative, that is, if the first peak position O1 does not coincide with the origin O, the deviation of the irradiation position of the laser light LB is corrected based on the coordinates of the origin O and the first deviation amount (step S20 in Figure 11).

[0129] In the correction method of this embodiment, if the judgment result of the ninth step is negative, that is, if the first peak position O1 does not coincide with the origin O, the manipulator 60 is adjusted (step S21 in FIG. 11), and then the process returns to the first step and the series of processes are repeatedly executed until the judgment result of the ninth step becomes positive.

[0130] According to this embodiment, it is possible to achieve the same effects as those achieved by the configuration and method shown in embodiment 1. That is, it is possible to accurately irradiate the desired position of the workpiece 200 along the weld line WL while scanning the laser beam LB two-dimensionally. This makes it possible to reduce the occurrence of welding defects and improve the welding yield.

[0131] Furthermore, according to this embodiment, it is possible to separately determine whether the deviation in the irradiation position of the laser beam LB—in this case, the deviation in the origin position during scanning—is due to insufficient adjustment of the manipulator 60 or temperature drift. Furthermore, if the deviation in the irradiation position occurs due to either of these factors, the deviation can be resolved by performing maintenance on the manipulator 60 or the correction procedure described in the first embodiment. This allows the laser beam LB to be irradiated along the predetermined weld line WL while scanning the workpiece 200 two-dimensionally, thereby preventing welding defects. Furthermore, there is no need to unnecessarily increase the frequency of periodic inspections and maintenance of the manipulator 60, thereby reducing downtime for the device. This prevents increases in the cost of the welding process.

[0132] In steps S19 to S21 shown in FIG. 11, it is determined whether the position P and the second peak position O2 coincide with each other, and if they do not coincide with each other, the deviation of the origin position during scanning may be corrected based on the coordinates of the position P and the deviation amount acquired in step S18.

[0133] In other words, the laser welding apparatus 100 of this embodiment is configured to correct the deviation of the origin position during scanning with the laser light LB based on either the deviation amount between the origin O and the first peak position O1 or the deviation amount between the position P and the second peak position O2.

[0134] Furthermore, in the method for correcting the deviation in the irradiation position of the laser beam LB in this embodiment, in a tenth step (step S19 in FIG. 11 ), it is determined whether or not the second peak position O2 coincides with the position P, and if the determination result in the eleventh step is negative, that is, if the second peak position O2 does not coincide with the position P, the deviation in the irradiation position of the laser beam LB may be corrected based on the coordinates of the position P and the second deviation amount (eleventh step; step S20 in FIG. 11 ).

[0135] The laser welding device of the present disclosure is useful because it can correct deviations in the irradiation position of the laser beam, particularly deviations in the origin position during scanning with the laser beam, with a simple configuration.

[0136] REFERENCE SIGNS LIST 10 Laser oscillator 20 Optical fiber 30 Laser head 31 Housing 32 Collimation lens 33 Mirror 34 First condenser lens 35 Protective glass 36 Aperture 37 Second condenser lens 38 Optical sensor 39 Optical system 40 Laser beam scanner 41 First galvanometer mirror 41a First mirror 41b First rotation axis 41c First drive unit 42 Second galvanometer mirror 42a Second mirror 42b Second rotation axis 42c Second drive unit 50 Controller 60 Manipulator 70 Stage 71 Main body 72 Correction unit 72a Reflector 72b Reflection spot 100 Laser welding device 200 Work

Claims

1. A laser welding device comprising at least a laser oscillator that generates laser light; a laser head that receives the laser light and irradiates it toward a workpiece; a controller that controls at least the operation of the laser head; and a stage on which the workpiece is placed, wherein the laser head has: a laser light scanner that scans the laser light in a first direction and a second direction intersecting the first direction; an optical sensor; and an optical system that causes reflected returning light of the laser light to be incident on the optical sensor, wherein the controller drives and controls the laser light scanner to scan the laser light two-dimensionally while causing the laser light to travel along a weld line, the stage having a correction unit, and the correction unit having a reflector and a reflection spot provided on the surface of the reflector, wherein the controller drives and controls the laser light scanner to irradiate the laser light around the reflection spot while scanning the laser light two-dimensionally and detects a first peak position where an output of the optical sensor reaches a peak, and the controller is configured to correct a deviation in the irradiation position of the laser light based on the center position of the reflection spot and the first peak position.

2. A laser welding device according to claim 1, characterized in that the controller is configured to correct the deviation of the origin position during scanning of the laser light based on the deviation amount between the center position of the reflection spot and the first peak position.

3. A laser welding device according to claim 1 or 2, wherein the laser oscillator and the laser head are connected by an optical fiber, and the laser light is transmitted from the laser oscillator to the laser head through the optical fiber.

4. A laser welding device according to any one of claims 1 to 3, characterized in that the laser beam scanner is composed of a first galvanometer mirror that scans the laser beam in the first direction, and a second galvanometer mirror that scans the laser beam in a second direction that intersects with the first direction.

5. A laser welding device according to any one of claims 1 to 4, wherein the laser head further has a focal position adjustment mechanism, and the focal position adjustment mechanism is configured to change the focal position of the laser light along a direction intersecting the surface of the workpiece.

6. A laser welding apparatus according to any one of claims 1 to 5, further comprising a manipulator to which the laser head is attached, wherein the controller controls the operation of the manipulator, and the manipulator moves the laser head in a predetermined direction relative to the surface of the workpiece.

7. A laser welding device as defined in claim 6, wherein when a first process of moving the laser head to the center position of the reflection spot and irradiating the laser light around the reflection spot while scanning the laser light two-dimensionally and a second process of moving the laser head to a predetermined position near the center position of the reflection spot and irradiating the laser light around the reflection spot while scanning the laser light two-dimensionally are performed, the controller is configured to correct a deviation in the irradiation position of the laser light based on the center position of the reflection spot, a first peak position where the output of the optical sensor peaks in the first process, and a second peak position where the output of the optical sensor peaks in the second process.

8. A laser welding device as described in claim 7, characterized in that, if the amount of deviation between the first peak position and the second peak position is within a predetermined tolerance range, the controller is configured to correct the deviation of the origin position during scanning of the laser light based on either the amount of deviation between the center position of the reflection spot and the first peak position, or the amount of deviation between the predetermined position and the second peak position.

9. A method for correcting deviation in the irradiation position of laser light using the laser welding apparatus of any one of claims 1 to 8, comprising the steps of: moving the laser head to the center position of the reflection spot; operating the laser light scanner to irradiate the laser light around the center position of the reflection spot while scanning it two-dimensionally; confirming a first peak position where the output of the optical sensor reaches a peak; determining whether or not the first peak position coincides with the center position of the reflection spot; terminating the correction operation if the first peak position coincides with the center position of the reflection spot; determining the amount of deviation between the first peak position and the center position of the reflection spot if the first peak position does not coincide with the center position of the reflection spot; and correcting the deviation of the irradiation position of the laser light based on the coordinates of the center position of the reflection spot and the amount of deviation.

10. A method for correcting deviation in the irradiation position of laser light using the laser welding apparatus of any one of claims 6 to 8, comprising: a first step of moving the laser head to the center position of the reflection spot; a second step of operating the laser light scanner to irradiate the laser light around the center position of the reflection spot while scanning it two-dimensionally; a third step of confirming a first peak position where the output of the optical sensor becomes a peak; a fourth step of determining the amount of deviation between the first peak position and the center position of the reflection spot; a fifth step of moving the laser head to a predetermined position near the center position of the reflection spot after determining the amount of deviation between the first peak position and the center position of the reflection spot; a sixth step of operating the laser light scanner to irradiate the laser light around the predetermined position while scanning it two-dimensionally; a seventh step of confirming a second peak position where the output of the optical sensor becomes a peak after the sixth step; and an eighth step of determining the amount of deviation between the second peak position and the predetermined position. a ninth step of determining whether a difference between a first deviation amount, which is a deviation amount between the first peak position and the center position of the reflection spot, and a second deviation amount, which is a deviation amount between the second peak position and the predetermined position, is within an allowable range; a tenth step of determining whether the first peak position coincides with the center position of the reflection spot if the determination result of the ninth step is affirmative; a step of terminating the correction work if the determination result of the tenth step is affirmative; an eleventh step of correcting the deviation of the laser beam irradiation position based on the coordinates of the center position of the reflection spot and the first deviation amount if the determination result of the tenth step is negative; and an eleventh step of adjusting the manipulator, after which the manipulator is adjusted, and returning to the first step, and repeatedly executing a series of processes until the determination result of the ninth step is affirmative.

11. A method for correcting deviation in the irradiation position of laser light as described in claim 10, wherein in the tenth step, it is determined whether or not the second peak position coincides with the predetermined position, and in the eleventh step, the deviation in the irradiation position of the laser light is corrected based on the coordinates of the predetermined position and the second deviation amount.

Images