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

Abstract

To provide a laser welding device that can correct, with a simple structure, deviation of an irradiation position of a laser beam.SOLUTION: A laser welding device 100 comprises a laser oscillator 10, a laser head 30, a controller 50 and a stage 70. The laser head 30 has a laser beam scanner 40 that two-dimensionally scans a laser beam LB. The controller 50 drives and controls the laser beam scanner 40. A beam sensor 80 is arranged so as to cover one end part of a through-hole 72b formed in the stage 70. When a circumference of the through-hole 72b is irradiated with the laser beam while the laser beam is two-dimensionally scanned, the controller 50 corrects deviation of an irradiation position of the laser beam LB, on the basis of a center position of the through-hole 72b and a first peak position O1 at which output of the beam sensor 80 is at a peak.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] Laser welding that irradiates laser light to weld a workpiece can perform high-quality welding because the power density of the laser light is high. Therefore, laser welding has been widely used in recent years.

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

[0004] However, in a laser welding apparatus using a galvanometer mirror, part of the laser light is absorbed by the galvanometer mirror, so the temperature of the galvanometer mirror rises during laser welding. Due to this influence, the irradiation position of the laser light may deviate from the set position. In addition to this, the temperature of the galvanometer mirror rises due to heat generation of the drive circuit that drives the galvanometer mirror or a rise in the temperature of the internal atmosphere of the welding apparatus during laser welding, and irradiation position deviation of the laser light may occur. Thus, due to various factors, the temperature of the galvanometer mirror rises, and irradiation position deviation of the laser light called temperature drift occurs.

[0005] In order to reduce the irradiation position deviation of the laser light caused by temperature drift, for example, Patent Document 2 discloses a laser processing apparatus including a CCD camera and a temperature sensor attached to a mounting portion of a galvanometer mirror or the like. The CCD camera detects the actual processing position by the laser light and corrects the deviation amount from the set position using the temperature measured by the temperature sensor and a correction coefficient table obtained in advance.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Patent Application Laid-Open No. 2005-95934 Patent Document 2 Japanese Patent Application Laid-Open No. 2005-40843 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, in the conventional configuration disclosed in Patent Document 2, the device configuration becomes complicated, and an expensive CCD camera is used only for checking and correcting temperature drift, resulting in high device costs. In addition, due to the influence of ambient lighting and the like, it may be difficult to detect the processing position by the CCD camera.

[0008] On the other hand, in addition to temperature drift, there are factors that cause displacement of the laser beam irradiation position. The main ones include insufficient adjustment, wear, or aging deterioration of the manipulator that holds and moves the laser head. If the adjustment of the operating mechanism of the manipulator is insufficient, or if wear or aging deterioration occurs, the irradiation position of the laser beam may deviate from the set position.

[0009] To solve this, regular inspection and maintenance of the manipulator are required. However, increasing the inspection frequency has problems such as lengthening the device downtime and increasing labor and maintenance costs.

[0010] The present disclosure has been made in view of such points, and an object thereof is to provide a laser welding apparatus and a method for correcting displacement of a laser beam irradiation position that can correct displacement of a laser beam irradiation position with a simple configuration. MEANS FOR SOLVING THE PROBLEMS

[0011] 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. The laser head has a laser light scanner that scans the laser light in each of a first direction and a second direction intersecting the first direction. The controller drives and controls the laser light scanner so as to two-dimensionally scan the laser light while causing the laser light to travel along a welding line. The stage has a correction unit, and the correction unit has a shielding part and a through hole that penetrates the shielding part in the thickness direction. A photosensor is disposed so as to cover one end of the through hole. When the laser light is irradiated around the through hole while the laser light is two-dimensionally scanned by the laser light scanner, the controller is configured to correct the deviation of the irradiation position of the laser light based on the center position of the through hole and a first peak position at which the output of the photosensor peaks.

[0012] A method for correcting the deviation of the irradiation position of laser light according to the present disclosure is a method for correcting the deviation of the irradiation position of laser light using the laser welding apparatus, and includes at least a step of moving the laser head to the center position of the through hole, a step of operating the laser light scanner to irradiate around the center position of the through hole while two-dimensionally scanning the laser light, a step of confirming a first peak position at which the output of the photosensor peaks, and a step of determining whether the first peak position coincides with the center position of the through hole. If the first peak position coincides with the center position of the through hole, the correction operation is terminated. If the first peak position does not coincide with the center position of the through hole, the amount of deviation between the first peak position and the center position of the through hole is obtained, and further includes a step of correcting the deviation of the irradiation position of the laser light based on the coordinates of the center position of the through hole and the amount of deviation.

Advantages of the Invention

[0013] According to the laser welding apparatus of the present disclosure, the irradiation position deviation of the laser beam can be corrected with a simple configuration. Further, according to the method for correcting the irradiation position deviation of the laser beam of the present disclosure, the irradiation position deviation of the laser beam can be easily corrected.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0016] (Embodiment 1) [Configuration of Laser Welding Apparatus] [Configuration of Laser Welding Apparatus and Laser Beam Scanner] FIG. 1 shows a schematic diagram of the configuration of the laser welding apparatus according to the present embodiment, and FIG. 2 shows a schematic configuration diagram of the laser beam scanner.

[0017] In the following description, the direction parallel to the traveling direction of the laser beam LB from the reflection mirror 33 toward the laser beam scanner 40 may be referred to as the X direction, the direction parallel to the optical axis of the laser beam LB emitted from the laser head 30 may be referred to as the Z direction, and the direction orthogonal to the X direction and the Z direction may be referred to as the Y direction, respectively. The XY plane including the X direction and the Y direction in the plane may be substantially parallel to the surface of the workpiece 200 or may form a certain angle with the surface when the surface of the workpiece 200 is a flat surface.

[0018] 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.

[0019] The laser oscillator 10 is a laser light source that generates a laser beam LB by being supplied with power from a power source (not shown). The laser oscillator 10 may be composed of a single laser light source or may be composed of a plurality of laser modules. In the latter case, the laser beams emitted from the plurality of laser modules are combined and emitted as the laser beam LB. Further, the laser light source or the laser module used in the laser oscillator 10 is appropriately selected according to the material of the workpiece 200, the shape of the welding portion, and the like.

[0020] The optical fiber 20 is optically coupled to the laser oscillator 10, and the laser beam LB generated by the laser oscillator 10 is incident on the optical fiber 20 and transmitted through the inside thereof toward the laser head 30.

[0021] The laser head 30 is attached to the end of the optical fiber 20 and irradiates the workpiece 200 with the laser beam LB transmitted from the optical fiber 20.

[0022] Further, the laser head 30 has, as optical components, a collimation lens 32, a reflection mirror 33, a condenser lens 34, and a laser beam scanner 40, and these optical components are accommodated in the housing 31 while maintaining a predetermined arrangement relationship.

[0023] The collimation lens 32 receives the laser beam LB emitted from the optical fiber 20, converts it into parallel light, and makes it incident on the reflection mirror 33. Further, the collimation lens 32 is connected to a drive unit (not shown) and is configured to be displaceable 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, and the laser beam LB can be appropriately irradiated according to the shape of the workpiece 200. That is, the collimation lens 32 also functions as a focal position adjustment mechanism for the laser beam LB in combination with a drive unit (not shown). In FIG. 1, an example in which the collimation lens 32 is composed of a single lens is shown. Although the focal position can be adjusted by driving the position of the collimation lens 32 in the Z direction, the parallelism of the laser beam LB emitted from the collimation lens 32 is somewhat reduced. In order to prevent this, it is desirable to configure the collimation lens 32 as a combination of a plurality of lenses. Note that the condensing lens 34 may be displaced by a drive unit to change the focal position of the laser beam LB.

[0024] The reflection mirror 33 reflects the laser beam LB that has passed through the collimation lens 32 and makes it incident on the laser scanner 40. The surface of the reflection mirror 33 is provided 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.

[0025] The condensing lens 34 condenses the laser beam LB that has been reflected by the reflection mirror 33 and scanned by the laser scanner 40 onto the surface of the workpiece 200.

[0026] As shown in FIG. 2, the laser light 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 axis 41b, and a first drive unit 41c, and the second galvanometer mirror 42 has a second mirror 42a, a second rotation axis 42b, and a second drive unit 42c. The laser light LB that has passed through the condenser lens 34 is reflected by the first mirror 41a and further reflected by the second mirror 42a, and is irradiated onto the surface of the workpiece 200.

[0027] For example, the first drive unit 41c and the second drive unit 42c are galvanometer motors, and the first rotation axis 41b and the second rotation axis 42b are output shafts of the motors. Although not shown, the first drive unit 41c is rotationally driven by a driver that operates in response to a control signal from the controller 50, so that the first mirror 41a attached to the first rotation axis 41b rotates around the axis of the first rotation axis 41b. Similarly, the second drive unit 42c is rotationally driven by a driver that operates in response to a control signal from the controller 50, so that the second mirror 42a attached to the second rotation axis 42b rotates around the axis of the second rotation axis 42b.

[0028] When the first mirror 41a rotates around the axis of the first rotation axis 41b by a predetermined angle, the laser light LB is scanned in the X direction. Also, when the second mirror 42a rotates around the axis of the second rotation axis 42b by a predetermined angle, the laser light LB is scanned in the Y direction. That is, the laser light scanner 40 is configured to two-dimensionally scan the laser light LB within the XY plane and irradiate it toward the workpiece 200.

[0029] The controller 50 controls the laser oscillation of the laser oscillator 10. Specifically, laser oscillation control is performed by supplying a control signal such as an output current or on-off time that has a predetermined relationship with the output of the laser light LB to a power supply (not shown) connected to the laser oscillator 10. Also, the controller 50 controls the output of the laser light LB.

[0030] Further, the controller 50 controls the operation of the laser head 30 according to the content of the selected laser welding program. Specifically, it performs drive control of the laser beam scanner 40 provided in the laser head 30 and a drive unit (not shown) of the collimation lens 32. Further, the controller 50 controls the operation of the manipulator 60.

[0031] The controller 50 has an integrated circuit such as an LSI or a microcomputer as an information processing unit 51, and realizes the functions of the controller 50 described above by executing a laser welding program, which is software, on this integrated circuit. Further, the controller 50 has a memory device such as a RAM, a ROM, or an SSD as a storage unit 52. The laser welding program is stored in the storage unit 52 and is called by the controller 50 according to an instruction from the controller 50. Note that the storage unit 52 may be a detachable SD card (registered trademark) for the controller 50. Further, the storage unit 52 may be provided at a location different from the controller 50.

[0032] Further, the storage unit 52 stores the correction result of the irradiation position deviation of the laser beam LB described later. For example, the deviation amount of the irradiation position of the laser beam LB due to temperature drift and its correction result are stored in the storage unit 52. Specifically, the deviation amount of the irradiation position of the laser beam LB caused by the absorption of the laser beam LB by the first galvanometer mirror 41 and the second galvanometer mirror 42 in the controller 50 and its correction result are stored in the storage unit 52. Alternatively, the deviation amount of the irradiation position of the laser beam LB caused by the heat generation of the drive circuit that drives these and its correction result are stored in the storage unit 52.

[0033] Note that the controller 50 that controls the operation of the laser head 30 and the controller 50 that controls the output of the laser beam LB may be provided separately.

[0034] The manipulator 60 is a multi-joint robot and is attached to the housing 31 of the laser head 30. Further, the manipulator 60 is connected to the controller 50 so as to be able to exchange signals, and moves the laser head 30 so as to draw a predetermined locus according to the above-described laser welding program. As a result, the laser beam LB is irradiated onto the surface of the workpiece 200 while two-dimensionally scanning along the welding line WL and around the welding line WL.

[0035] Note that another controller (not shown) for controlling the operation of the manipulator 60 may be provided. However, also in that case, in order to configure the irradiation position of the laser beam LB, it is necessary to be configured to be able to perform data communication with the controller 50 that controls the operation of the laser head 30.

[0036] The stage 70 has a main body portion 71 and a correction portion 72. The configuration of the stage 70 will be described in detail later.

[0037] The laser welding apparatus 100 shown in FIG. 1 can perform laser welding on workpieces 200 having various shapes.

[0038] [Configuration of Stage] FIG. 3 shows a plan view of the stage, FIG. 4 shows an enlarged plan view of the correction portion, and FIG. 5 shows a schematic cross-sectional view taken along line V-V of FIG. 4.

[0039] As shown in FIG. 3, the stage 70 has a main body portion 71 and a correction portion 72. The workpiece 200 is placed on the main body portion 71, and the workpiece 200 is welded by irradiation with the laser beam LB. For this reason, although not shown, the main body portion 71 includes a portion having a flat surface for supporting the workpiece 200 and a portion through which the laser beam LB passes.

[0040] On one hand, the correction part 72 is arranged at a corner of the main body part 71. As shown in FIGS. 4 and 5, the correction part 72 has a shielding part 72a that shields the laser beam LB, and a through hole 72b that penetrates the shielding part 72a in the Z direction, which is its thickness direction. Note that the diameter d of the through hole 72b is set to be about 1 / 10 times to equal times (1 time) the diameter of the laser beam LB. The thickness of the shielding part 72a should be as thin as possible as long as the strength for installation and fixation is sufficient. For example, those with a thickness of 1 mm or less can also be used. Also, the thickness may be set according to the divergence angle of the incident laser beam LB. In this case, the larger the divergence angle of the laser beam LB, the thinner the thickness of the shielding part 72a is preferably.

[0041] Also, an optical sensor 80 is arranged so as to cover one end of the through hole 72b in the Z direction. When the laser beam LB is irradiated to the correction part 72 while being sequentially scanned at predetermined intervals in the X direction and the Y direction respectively along the broken line shown in FIG. 4, the laser beam LB that has passed through the through hole 72b is incident on the optical sensor 80. In parts other than the through hole 72b, the laser beam LB is reflected and scattered in the direction opposite to the incident direction.

[0042] As described later, the correction part 72 is used in the laser scanner 40 to determine whether the aforementioned temperature drift has occurred, and if it has occurred, to measure the correction amount of the temperature drift.

[0043] Note that the position of the correction part 72 on the stage 70 is not particularly limited to that shown in FIG. 3. However, during the laser welding of the workpiece 200, spatter scatters near the welding line WL, or when the workpiece 200 contains aluminum, smut adheres. To prevent these from adhering to the through hole 72b or the optical sensor 80, it is necessary to arrange the welding line of the workpiece 200 at a position that is a predetermined distance or more away from the correction part 72. Also, in a welding process that is not in use, since the correction part 72 is not used, a cover (not shown) may be attached to protect its surface.

[0044] [Method for Correcting Irradiation Position Deviation of Laser Light] FIG. 6 shows a flowchart of a correction procedure for irradiation position deviation of laser light, and FIG. 7 shows a schematic diagram when the output of the optical sensor is plotted on the XY plane where the laser light is scanned.

[0045] In the correction unit 72 shown in FIG. 3, the center position of the through hole 72b on the XY plane is made to coincide with the galvanometer origin of the laser scanner 40, and it is set 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 when there is no temperature drift. In other words, the galvanometer origin corresponds to the initial position on the XY plane at the tip of the manipulator 60. The origin O is stored in the storage unit 52 as coordinates on the XY plane.

[0046] When there is no temperature drift, an output signal is generated by the optical sensor 80 only when the laser light LB irradiates the origin O and its vicinity. Here, the "vicinity" in this case refers to a distance that is about 1 / 10 to 1 / 2 of the radius when the laser light LB is focused on the XY plane from the origin O. Needless to say, this distance can also be shortened. In that case, the accuracy of the correction described later becomes higher.

[0047] On the other hand, when temperature drift occurs, due to its influence, when scanning the laser light LB, the origin during scanning may deviate from the origin O corresponding to the galvanometer origin. That is, when the laser light LB is irradiated at a position that is a predetermined distance or more away from the origin O, an output signal may be generated by the optical sensor 80.

[0048] When such a situation occurs, it becomes impossible to irradiate the work 200 with the laser light LB along the desired irradiation trajectory, which may cause welding defects.

[0049] Note that the "origin during scanning" refers to the case where, when irradiating the surface of the work 200 or the stage 70 with the laser light scanner 40 during actual welding or correction described later, both the position command in the X-axis direction and the position command in the Y-axis direction are zero (or a fixed value corresponding to the laser light scanner 40. For the sake of explanation, this value is considered zero hereinafter), which corresponds to the actual irradiation point of the laser light LB on the XY plane. The position command in the X-axis direction is a command for the rotational position of the first drive unit 41c (hereinafter referred to as a rotation command), and the position command in the Y-axis direction is a rotation command for the second drive unit 42c. In this case, since both the position commands in the X-axis direction and the Y-axis direction are zero, the origin during scanning coincides with the galvanometer origin when there is no temperature drift.

[0050] Therefore, by correcting the deviation of the irradiation position of the laser light LB, in this case, the origin position during scanning, according to the procedure shown in FIG. 6, the laser light LB can be irradiated on the work 200 along a desired irradiation trajectory, and the occurrence of welding defects can be suppressed. This will be further explained below.

[0051] Move the manipulator 60 to move the laser light scanner 40 of the laser head 30 to the center position of the through hole 72b of the correction unit 72, that is, the origin O, on the XY plane (step S1 in FIG. 6).

[0052] Operate the laser light scanner 40 to irradiate around the origin O while scanning the laser light LB along the broken line shown in FIG. 4 (step S2 in FIG. 6). In step S2, the manipulator 60 is not moved. That is, the position of the laser head 30 itself scans the laser light LB along the broken line shown in FIG. 4 while keeping the origin O. Also, the output of the laser light LB in step S2 is significantly reduced compared to during laser welding. This is to prevent damage to the shielding portion 72a and the optical sensor 80. For example, when the output of the laser light LB during laser welding is several kW, the output of the laser light LB in step S2 may be a value (about several mW) that does not damage the shielding plate 72a or the through hole 72b and can be sufficiently detected by the optical sensor 38. Usually, in the laser oscillator 10, a guide laser (not shown) may be used to visually recognize the irradiation position of the laser light LB, but the laser light emitted from this guide laser may be scanned in step S2 described above.

[0053] During or after the execution of step S2, check the output of the optical sensor 80 and check the first peak position O1 where the output peaks (step S3 in FIG. 6). The first peak position O1 is represented by coordinates on the XY plane. Also, the coordinates of the first peak position O1 and the output of the optical sensor 80 at the first peak position O1 are stored in the storage unit 52.

[0054] 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. 6). Note that in this specification, "coincidence" includes not only strict coincidence but also cases where the distance between the first peak position O1 and the origin O on the XY plane is about 1 / 10 to 1 / 2 or less 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 becomes higher.

[0055] Note that the position where the laser beam LB reflected by the first galvanometer mirror 41 and the second galvanometer mirror 42 fixed in the preset initial position is irradiated on 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 through hole 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 fixed in their respective initial positions. In this case, if there is no temperature drift, the origin during the scanning of the laser beam LB coincides with the aforementioned origin O, and the output from the optical sensor 80 becomes a peak.

[0056] If the determination result in step S4 is affirmative, that is, if the first peak position O1 coincides with the origin O, it is determined that the origin during the scanning of the laser beam LB coincides with the origin O. That is, since it can be determined that no temperature drift has occurred in the laser beam scanner 40, a series of operations are terminated.

[0057] 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, as shown in FIG. 7, on the XY plane, the peak of the output of the optical sensor 80 appears at a position away from the origin O. In the example shown in FIG. 7, the first peak position O1 is shifted to the negative side in both the X direction and the Y direction with respect to the origin O.

[0058] 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, that is, the deviation amount between the origin O and the first peak position O1, and stores the deviation amount in the storage unit 52 (step S5 in FIG. 6).

[0059] 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 FIG. 6).

[0060] In the example shown in FIG. 7, the origin position during scanning after correction satisfies the relationships shown in equations (1) and (2).

[0061] Xc = X0 - Xa ···(1) Yc = Y0 - Ya ···(2) Here, X0: X coordinate of the origin during scanning in the absence of temperature drift Y0: Y coordinate of the origin during scanning in the absence of temperature drift Xc: X coordinate of the origin during scanning after correction Yc: Y coordinate of the origin during scanning after correction Xa: Amount of deviation in the X direction between the origin O and the first peak position O1 Ya: Amount of deviation in the Y direction between the origin O and the first peak position O1 That is. As described above, since the galvanometer origin of the laser scanner 40 is set as the origin O, in equations (1) and (2), both the X coordinate X0 of the origin and the Y coordinate Y0 of the origin may be set to zero. In the example shown in FIG. 8, both the deviation amount Xa and the deviation amount Ya take negative values.

[0062] 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, with respect to the rotation command corresponding to the originally set origin during scanning (= (X0, Y0)), a rotation amount corresponding to the deviation amounts Xa and Ya is added or subtracted to correct the rotation command corresponding to the origin during scanning.

[0063] The coordinates (Xc, Yc) of the origin during scanning after correction and the deviation amounts Xa and Ya are stored in the storage unit 52. Also, the correction amounts of the rotation commands of the first drive unit 41c and the second drive unit 42c corresponding to the deviation amounts Xa and Ya respectively are stored in the storage unit 52. In subsequent laser welding, when scanning the laser beam LB, the coordinates of the origin during scanning are set to (Xc, Yc).

[0064] [Effects, etc.] As described above, the laser welding apparatus 100 according to the present embodiment includes at least a laser oscillator 10 that generates a laser beam LB, a laser head 30 that receives the laser beam LB and irradiates the workpiece 200, a controller 50 that controls the operation of the laser head 30 and the output P of the laser beam LB, and a stage 70 on which the workpiece 200 is placed.

[0065] The laser head 30 has a laser light scanner 40 that scans the laser light LB in each of the X direction (first direction) and the Y direction (second direction) intersecting the X direction.

[0066] The controller 50 drives and controls the laser light scanner 40 so as to two-dimensionally scan the laser light LB while advancing the laser light LB along the welding line WL.

[0067] The stage 70 has a main body portion 71 and a correction portion 72. The correction portion 72 has a shielding portion 72a and a through hole 72b that penetrates the shielding portion 72a in the thickness direction. When the laser light LB is incident on the through hole 72b, an optical sensor 80 is disposed so as to cover one end of the through hole 72b corresponding to the emission port of the laser light LB.

[0068] While two-dimensionally scanning the laser light LB with the laser light scanner 40, the laser light LB is irradiated around the through hole 72b. In this case, the controller 50 is configured to correct the deviation of the irradiation position of the laser light LB based on the origin O which is the center position of the through hole 72b and the first peak position O1 where the output of the optical sensor 80 peaks.

[0069] According to the present embodiment, by providing the correction portion 72 having the through hole 72b in the stage 70 and disposing the optical sensor 80 so as to cover one end of the through hole 72b, the deviation of the irradiation position of the laser light LB can be corrected with a very simple configuration. Further, while two-dimensionally scanning the laser light LB, it is possible to accurately irradiate a desired position of the workpiece 200 along the welding line WL. Thereby, the occurrence of welding defects can be reduced and the welding yield can be improved.

[0070] Further, the controller 50 is configured to correct the deviation of the origin position during the scanning of the laser light LB based on the deviation amount between the origin O which is the center position of the through hole 72b and the first peak position O1.

[0071] By doing so, it is possible to easily correct the deviation of the irradiation position of the laser beam LB caused particularly by temperature drift.

[0072] The laser oscillator 10 and the laser head 30 are connected by an optical fiber 20, and the laser beam LB is transmitted from the laser oscillator 10 to the laser head 30 through the optical fiber 20.

[0073] By providing the optical fiber 20 in this way, it becomes possible to perform laser welding on the workpiece 200 installed at a position away from the laser oscillator 10. As a result, the degree of freedom in arranging each part of the laser welding apparatus 100 is increased.

[0074] 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.

[0075] By configuring the laser beam scanner 40 in this way, the laser beam LB can be easily scanned two-dimensionally. In addition, 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.

[0076] The laser head 30 further has a collimation lens 32, and the collimation lens 32 is configured to change the focal position of the laser beam LB along the Z direction that intersects each of the X direction and the Y direction. In other words, the collimation lens 32 is configured to change the focal position of the laser beam LB along the Z direction that intersects the surface of the workpiece 200. That is, the collimation lens 32 also functions as a focal position adjustment mechanism for the laser beam LB in combination with a drive unit (not shown). That is, the focal position can be changed according to an arbitrary irradiation position during welding, and the degree of freedom in setting welding conditions can be increased.

[0077] By doing so, the focal position of the laser beam LB can be easily changed, and the laser beam LB can be appropriately irradiated according to the shape of the workpiece 200.

[0078] 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 with respect to the surface of the workpiece 200.

[0079] By providing the manipulator 60 in this way, the welding direction or the weld point position of the laser beam LB can be changed. Further, laser welding can be easily performed on a workpiece 200 having a complex shape, for example, a three-dimensional shape.

[0080] The method for correcting the irradiation position deviation of the laser beam according to the present embodiment at least includes a first step (step S1 in FIG. 6) of moving the laser head 30 to the origin O which is the center position of the through hole 72b, and a second step (step S2 in FIG. 6) of operating the laser beam scanner 40 to irradiate around the origin O while two-dimensionally scanning the laser beam LB.

[0081] Further, it includes a third step (step S3 in FIG. 6) of checking the first peak position O1 at which the output of the optical sensor 80 peaks, and a fourth step (step S3 in FIG. 6) of determining whether the first peak position O1 coincides with the origin O.

[0082] If the determination result in the fourth step is affirmative, that is, if the first peak position O1 coincides with the origin O, the correction work is terminated.

[0083] If the determination result in the fourth step is negative, that is, if the first peak position O1 does not coincide with the origin O, it further includes a step of obtaining the deviation amount between the first peak position O1 and the origin O, and correcting the irradiation position deviation of the laser beam LB based on the coordinates of the origin O and the deviation amount.

[0084] By doing so, in particular, it is possible to easily correct the deviation of the irradiation position of the laser beam LB caused by temperature drift. Further, while two-dimensionally scanning the laser beam LB, it is possible to accurately irradiate a desired position of the workpiece 200 along the welding line WL. As a result, the occurrence of welding defects can be reduced and the welding yield can be improved.

[0085] (Embodiment 2) FIG. 8 shows a flowchart of a procedure for correcting the deviation of the irradiation position of the laser beam according to the present embodiment.

[0086] In Embodiment 1, the apparatus configuration and the correction procedure for correcting the deviation of the irradiation position of the laser beam LB caused by temperature drift have been described.

[0087] On the other hand, as described above, the deviation of the irradiation position of the laser beam LB may also occur due to insufficient adjustment, wear, or aging deterioration of the manipulator 60. When the adjustment of the manipulator 60 is insufficient, or when wear or aging deterioration occurs, the tip position of the manipulator 60 itself may deviate from the position preset in the welding program or the like. In this case, since the position of the laser head 30 also deviates, it is not possible to irradiate the workpiece 200 with the laser beam LB at a predetermined position.

[0088] Therefore, the adjustment state of the manipulator 60 is confirmed by the procedure shown in FIG. 8, and the deviation of the irradiation position of the laser beam LB is corrected based on the result. Details will be described below.

[0089] First, move the manipulator 60 to move the laser scanner 40 of the laser head 30 to the aforementioned origin O (step S10). Operate the laser scanner 40 to irradiate around the origin O while scanning the laser beam LB along the broken line shown in FIG. 4 (step S11). Further, check the output of the optical sensor 80 and check the first peak position O1 where the output peaks (step S13). Subsequently, obtain the deviation amount (first deviation amount) between the origin O and the first peak position O1, and store the first deviation amount 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. 6.

[0090] Next, move the manipulator 60 to move the laser scanner 40 of the laser head 30 to a predetermined position P near the aforementioned origin O (hereinafter simply referred to as position P; see FIG. 4) (step S14). Position P is a position previously stored in the controller 50 during robot teaching. In the example shown in FIG. 4, in the scanning trajectory of the laser beam LB shown by the broken line, it is shifted by one section each in the X direction and the Y direction from the origin O. However, the position P based on the origin O is not particularly limited to this and may be set to another position. The distance between position P and the origin O is also a value previously stored in the controller 50. Note that it is desirable that both position P and the origin O are not on the X-axis or the Y-axis of the aforementioned XY plane. This is because the correction of the irradiation position deviation of the laser beam LB that requires maintenance of the manipulator 60 may exist in both the X-axis and the Y-axis. The specific content of step S14 is the same process as step S10 except that the destination of the movement of the laser scanner 40 is different.

[0091] Furthermore, operate the laser scanner 40 to irradiate around position P while scanning the laser beam LB along the broken line shown in FIG. 4 (step S15). Check the output of the optical sensor 80 and check the second peak position O2 where the output peaks (step S16). Subsequently, obtain the deviation amount (second deviation amount) between position P and the second peak position O2, and store the second deviation amount in the storage unit 52 (step S17). Note that steps S15 to S17 are the same processes as steps S11 to S13.

[0092] Next, the information processing unit 51 of the controller 50 calculates the deviation amount 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 amount and the second deviation amount. Further, it is determined whether or not the deviation amount between the first peak position O1 based on the origin O and the second peak position O2 based on the position P is within the allowable range (step S18).

[0093] That is, in step S18, when the deviation amount in the X direction between the origin O and the second peak position O2 based on the position P is Xb, and the deviation amount in the Y direction between the origin O and the second peak position O2 based on the position P is Yb, it is determined whether or not the relationship satisfying the expressions (3) and (4) is satisfied.

[0094] |Xa - Xb| ≤ εx ···(3) |Ya - Yb| ≤ εy ···(4) 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 appropriately set according to the processing tolerance allowed during laser welding, the assembly tolerance of the manipulator 60, and the like.

[0095] If the determination result in step S18 is affirmative, it can be determined that the position of the manipulator 60 has not deviated from the set position or the difference is within the allowable range. Therefore, the process proceeds to step S19.

[0096] Steps S19 to S21 are the same processes as steps S4 to S6 in FIG. 6, so detailed description is omitted. That is, if the determination result in step S19 is affirmative, the correction work is terminated. If the determination result in 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 obtained in step S14 (step S20).

[0097] 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 by exceeding the allowable range. Therefore, the laser welding apparatus 100 is stopped, the manipulator 60 is maintained, and the position, posture, etc. are readjusted.

[0098] Thereafter, the process returns to step S10, and a series of processes are repeatedly executed until the determination result in step S18 becomes affirmative. Further, steps S19 and subsequent steps are executed to correct the deviation of the origin position during scanning, and the correction work is terminated.

[0099] As described above, in the laser welding apparatus 100 according to the present embodiment, the first process and the second process are respectively executed.

[0100] In the first process, the laser head 30 is moved to the center position of the through hole 72b, that is, the origin O, and while the laser beam LB is two-dimensionally scanned, the laser beam LB is irradiated around the origin O (around the through hole 72b) (steps S10 and S11 in FIG. 8).

[0101] In the second process, the laser head 30 is moved to a predetermined position P near the origin O, and while the laser beam LB is two-dimensionally scanned, the laser beam LB is irradiated around the position P (around the through hole 72b) (steps S14 and S15 in FIG. 8).

[0102] When the first process and the second process are executed, the controller 50 is configured to correct the irradiation position deviation of the laser beam LB based on the origin O which is the center position of the through hole 72b, the first peak position O1 where the output of the optical sensor 80 peaks in the first process, and the second peak position O2 where the output of the optical sensor 80 peaks in the second process.

[0103] Furthermore, if the deviation amount between the first peak position O1 and the second peak position O2 is within a predetermined allowable range, the controller 50 is configured to correct the deviation of the origin position during scanning of the laser beam LB based on the deviation amount between the origin O and the first peak position O1.

[0104] In addition, the method for correcting the irradiation position deviation of the laser beam LB in the present embodiment includes at least a first step (step S10 in FIG. 8) of moving the laser head 30 to the origin O.

[0105] Furthermore, a second step (step S11 in FIG. 8) of operating the laser scanner 40 to irradiate around the origin O while two-dimensionally scanning the laser beam LB, a third step (step S12 in FIG. 8) of checking the first peak position O1 where the output of the optical sensor 80 peaks, and a fourth step (step S13 in FIG. 8) of obtaining the deviation amount (first deviation amount) between the first peak position O1 and the origin O are provided.

[0106] Furthermore, after obtaining the first deviation amount, a fifth step (step S14 in FIG. 8) of moving the laser head 30 to the position P, and a sixth step (step S15 in FIG. 8) of operating the laser scanner 40 to irradiate around the position P while two-dimensionally scanning the laser beam LB are provided.

[0107] After the seventh step, a seventh step (step S16 in FIG. 8) of checking the second peak position O2 where the output of the optical sensor 80 peaks, and an eighth step (step S17 in FIG. 8) of obtaining the deviation amount (second deviation amount) between the second peak position O2 and the position P are provided.

[0108] Furthermore, a ninth step (step S18 in FIG. 8) of determining whether the difference between the first deviation amount and the second deviation amount is within the allowable range is provided.

[0109] If the determination result of the ninth step is affirmative, that is, if the difference between the first deviation amount and the second deviation amount is within the aforementioned allowable range, a tenth step (step S19 in FIG. 8) of determining whether the first peak position O1 coincides with the origin O is further provided.

[0110] If the determination result of the tenth step is affirmative, that is, if the first peak position O1 coincides with the origin O, the correction work is terminated.

[0111] If the determination result of the 10th step is negative, that is, if the first peak position O1 does not coincide with the origin O, the shift of the irradiation position of the laser beam LB is corrected based on the coordinates of the origin O and the first shift amount (11th step; step S20 in FIG. 8).

[0112] If the determination result of the 9th step is negative, that is, if the first peak position O1 does not coincide with the origin O, after adjusting the manipulator 60 (step S21 in FIG. 8), the process returns to the first step, and a series of processes are repeatedly executed until the determination result of the 9th step becomes positive.

[0113] According to the present embodiment, the same effects as those achieved by the configuration and method shown in the first embodiment can be achieved. That is, while two-dimensionally scanning the laser beam LB, it is possible to accurately irradiate a desired position of the workpiece 200 along the welding line WL. This can reduce the occurrence of welding defects and improve the welding yield.

[0114] Further, according to the present embodiment, it is possible to separately determine whether the shift of the irradiation position of the laser beam LB, in this case, the shift of the origin position during scanning, is due to insufficient adjustment of the manipulator 60 or due to temperature drift. Also, when the irradiation position is shifted due to each factor, the irradiation position shift can be eliminated by performing maintenance of the manipulator 60 or the correction procedure shown in the first embodiment. As a result, it is possible to irradiate the workpiece 200 along a predetermined welding line WL while two-dimensionally scanning the laser beam LB, and suppress the occurrence of welding defects. In addition, it is not necessary to increase the frequency of regular inspection and maintenance of the manipulator 60 unnecessarily, and the downtime of the apparatus can be reduced. Therefore, an increase in the cost of the welding process can be suppressed.

[0115] In steps S19 to S21 shown in FIG. 8, it may be determined whether the position P coincides with the second peak position O2, and if not, the shift of the origin position during scanning may be corrected based on the coordinates of the position P and the shift amount obtained in step S17.

[0116] That is, the laser welding apparatus 100 of the present embodiment is configured to correct the deviation of the origin position during the scanning of the laser beam 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.

[0117] In addition, the method for correcting the irradiation position deviation of the laser beam LB of the present embodiment determines whether the second peak position O2 coincides with the position P in the tenth step (step S19 in FIG. 8). If the determination result in the tenth step is negative, that is, if the second peak position O2 does not coincide with the position P, the irradiation position deviation of the laser beam LB may be corrected (eleventh step; step S20 in FIG. 8) based on the coordinates of the position P and the second deviation amount.

Industrial Applicability

[0118] The laser welding apparatus of the present disclosure has a simple configuration and can correct the irradiation position deviation of the laser beam, particularly the deviation of the origin position during the scanning of the laser beam, and is useful.

Explanation of Reference Numerals

[0119] 10 Laser oscillator 20 Optical fiber 30 Laser head 31 Housing 32 Collimation lens 33 Reflective mirror 34 Condensing lens 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 Body part 72 Correction part 72a Shielding part 72b Through-hole 80 Optical sensor 100 Laser welding device 200 Workpiece

Claims

1. A laser oscillator that generates a laser beam, a laser head that receives the laser beam and irradiates a workpiece therewith, a controller that controls at least the operation of the laser head, and a stage on which the workpiece is placed, and comprising at least: the laser head has a laser beam scanner that scans the laser beam in each of a first direction and a second direction intersecting the first direction; the controller drives and controls the laser beam scanner so as to two-dimensionally scan the laser beam while advancing the laser beam along a welding line; the stage has a correction unit; the correction unit has a shielding part and a through hole that penetrates the shielding part in the thickness direction; an optical sensor is disposed so as to cover one end of the through hole; when the laser beam is irradiated around the through hole while two-dimensionally scanning the laser beam with the laser beam scanner; the controller is configured to correct the deviation of the irradiation position of the laser beam based on the center position of the through hole and a first peak position at which the output of the optical sensor peaks. A laser welding apparatus characterized by that.

2. In the laser welding apparatus according to Claim 1, the controller is configured to correct the deviation of the origin position during scanning of the laser beam based on the deviation amount between the center position of the through hole and the first peak position. A laser welding apparatus characterized by that.

3. In the laser welding apparatus according to Claim 1 or 2, the laser oscillator and the laser head are connected by an optical fiber, and the laser beam is transmitted from the laser oscillator to the laser head through the optical fiber. A laser welding apparatus characterized by that.

4. In the laser welding apparatus according to any one of Claims 1 to 3, 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 intersecting the first direction. A laser welding apparatus characterized by that.

5. In the laser welding apparatus according to any one of Claims 1 to 4, 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 beam along a direction intersecting the surface of the workpiece. A laser welding apparatus characterized by that.

6. In the laser welding apparatus according to any one of claims 1 to 5, further comprising a manipulator to which the laser head is attached, the controller controls the operation of the manipulator, the manipulator is characterized in that the laser head is moved in a predetermined direction with respect to the surface of the workpiece, and the laser welding apparatus.

7. In the laser welding apparatus according to claim 6, a first process of moving the laser head to the center position of the through hole and irradiating the laser light around the through hole while two-dimensionally scanning the laser light; a second process of moving the laser head to a predetermined position near the center position of the through hole and irradiating the laser light around the through hole while two-dimensionally scanning the laser light; when executed, the controller is configured to correct the deviation of the irradiation position of the laser light based on the center position of the through hole, 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. A laser welding apparatus characterized by that.

8. In the laser welding apparatus according to claim 7, if the deviation amount between the first peak position and the second peak position is within a predetermined allowable range, the controller is configured to correct the deviation of the origin position during the scanning of the laser light based on either the deviation amount between the center position of the through hole and the first peak position or the deviation amount between the predetermined position and the second peak position. A laser welding apparatus characterized by that.

9. A method for correcting the deviation of the irradiation position of laser light using the laser welding apparatus according to any one of claims 1 to 8, moving the laser head to the center position of the through hole; operating the laser light scanner to irradiate around the center position of the through hole while two-dimensionally scanning the laser light; confirming a first peak position where the output of the optical sensor peaks; at least comprising a step of determining whether the first peak position coincides with the center position of the through hole, if the first peak position coincides with the center position of the through hole, the correction operation is terminated, If the first peak position does not coincide with the center position of the through hole, the deviation amount between the first peak position and the center position of the through hole is obtained, and based on the coordinates of the center position of the through hole and the deviation amount, a method for correcting the irradiation position deviation of the laser beam, further comprising the step of correcting the irradiation position deviation of the laser beam.

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

11. In the method for correcting the deviation of the irradiation position of the laser beam according to claim 10, in the tenth step, it is determined whether or not the second peak position coincides with the predetermined position, in the eleventh step, the deviation of the irradiation position of the laser beam is corrected based on the coordinates of the predetermined position and the second deviation amount. A method for correcting the deviation of the irradiation position of the laser beam, characterized by this.

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